# Calibrating for accuracy is underwhelming, am I missing something ?



## Doctor X (Apr 3, 2007)

Hi there,

I have an SVS PB10 ISD. I have calibrated to 72 dB with my Radio Shack SPL meter and so far I must say that watching films at reference level is underwhelming.

I must be missing something. I watched Pearl Harbour at reference level and the scene where the big ship explodes produces virtually no felt impact. You know that there is bass but it's not loud. When Cuba gets hold of those massive machine guns, there is supposed to be under 20 hz information recorded.

With my PB10 ISD, there is virtually no deep bass whatsoever. This is again, calibrated at 72 dB for the sub and 75 dB for the rest of the mains. Now I know that I could always increase the sub level but is this supposed to sound this way ? 

The phase control is turned to 180 deg. Turning it to 0 deg made little difference to the ears. DRC has been turned off in the receiver as well as in the dvd player menu.

I mean, for those who watch at reference level and calibrate their subwoofers accurately, is this supposed to sound like this ? My room is about 2500 cubic feet. 

I have REW but I lack the cables to try the software out. I've heard of the Velodyne SM1 and people tell me that it's the best tool to use right now. Is it possible that my subwoofer is defective ? 

And are there any tests that you guys propose I should undertake to make sure that the subwoofer is not underperforming ? 

--Regards,


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## Doctor X (Apr 3, 2007)

Is it possible that perhaps my Radio Shack SPL meter isn't calibrated accurately ? 

--Regards,


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## Blaser (Aug 28, 2006)

Hi there!

First why did you calibrate your sub at -3 db? FYI, I calibrate my subs between +5 and +10 db to start feeling them pleasantly.... depending on movie.

Second, filling 2500 cuft with a pb-10 is not an easy task. What did you base your choice of this sub for this room on, while you listen at RL?

Third, Is it possible to run an FR sweep with REW at LP?

Fourth will be upon your reply to the above...

B. R.


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## Otto (May 18, 2006)

Vaughan100 said:


> With my PB10 ISD, there is virtually no deep bass whatsoever. This is again, calibrated at 72 dB for the sub and 75 dB for the rest of the mains. Now I know that I could always increase the sub level but is this supposed to sound this way ?


Hi Vaughan100,

Well, as blaser pointed out, your sub is 3 dB cooler than your mains. Most people go the "other way" -- sub hotter than mains. Bump up the level in your receiver by about 6 dB and see if you notice a difference. Although I calibrate my levels like you are, I frequently tweak the sub's level based on the program material -- some things are just recorded with too little bass, and some things with too much, so I have to compensate for those changes myself. 



> I mean, for those who watch at reference level and calibrate their subwoofers accurately, is this supposed to sound like this ? My room is about 2500 cubic feet.


Well, also like blaser noted, your sub might be a little light for that size room. I don't have any experience with it first hand, but a 10" driver might not quite make it. You could certainly turn it up and see how it goes.

To answer your question, though, no, my sub doesn't sound weak, but I'm using four 18s. :bigsmile: My room is open to other areas of the house and is more than 3,000 cubic feet.



> I have REW but I lack the cables to try the software out. I've heard of the Velodyne SM1 and people tell me that it's the best tool to use right now. Is it possible that my subwoofer is defective ?


Well, the SMS-1 may be the _easiest_ but I wouldn't necessarily consider it the best. I've not used on myself, but I understand that it can achieve similar results to the BFD. The BFD is much, much more reasonably priced, but also requires more user input. So, if you like to tweak, or if you want to save money, or both, the BFD is for you. If you don't care about "playing with it" or you don't care about budget, then go with the SMS-1. For me, it's not so much about the budget, but just the utter acccessibility to all settings that leads me to continue to use the BFD. I'm more of a tweaker. It also interfaces seamlessly with REW, which is much more powerful than the SMS-1 interface for doing actual subwoofer frequency response measurements. 

I doubt your sub is actually defective. It's making sound and not "flubbing" or "popping", right? Turn things up a little bit and see what happens.



> And are there any tests that you guys propose I should undertake to make sure that the subwoofer is not underperforming ?
> 
> Get REW up and running and take some measurements. I would not be surprised if your room interaction with the sub is giving you a poor frequency response. Also, you might try moving the sub to different positions within the room. Is it corner loaded currently?
> 
> ...


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## mojomike (Feb 12, 2007)

A couple of points to note:

The ears have a lower sensitivity to bass at lower volumes. If you are listening at less than reference level as most of us do most of the time, you may want to run the sub several db "hot" to compensate for this hearing roll-off.

Many of us run our subs a little hot because we prefer them that way. If your frequency response is relatively free of large peaks, the sub can be run a little hot without sounding boomy or obnoxious.

I would suggest using the calibration as a known starting point, then dial up the gain on the sub to your taste.


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## bobgpsr (Apr 20, 2006)

blaser said:


> First why did you calibrate your sub at -3 db?


I don't think he is really. Remember you need to compensate for the reduced (low frequency) sensitivity of the RS SPL meter when measuring a subwoofer test tone (especially the Avia one -- although AVR sub test tones are similar) So a reading of 72 on the SPL meter in reallity is more like 75. When you use one of the RS SPL calibration files with REW then this is all taken care of.


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## Doctor X (Apr 3, 2007)

> First why did you calibrate your sub at -3 db? FYI, I calibrate my subs between +5 and +10 db to start feeling them pleasantly.... depending on movie.


As far as I know, the Radio Shack SPL meter reads too "hot" on average. A 75 dB reading would be "78" according to many people on AVSforum. So I took their advice and calibrated equal with the mains so that "72" dB actually will mean that it's level matched with the speakers at 75 dB.

--Regards,


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## OvalNut (Jul 18, 2006)

[edit] The following post I made is INCORRECT. [/edit]
It's the other way around. I know I always got similarly confused....:mooooh:

The RS spl meter is generally 2-3 db insensitive at very low frequencies, so in order to calibrate flat with your mains you need to set your subwoofer to read 2-3 db more than your mains.

Example: If you calibrate so that your mains register 75db, then calibrate your subwoofer to register 77-78db. Then, your subwoofer will be calbrated approximated level with the mains.
[edit] end of INCORRECT post. [/edit]

Tim
:drive:


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## Doctor X (Apr 3, 2007)

Are you sure about that Ovalnut ? I'm not disagreeing but I'm sure I've heard from many highly knowledgeable members (Ed Mullen, Tom V etc) among others that a 72 dB reading yields a 3 dB increase because of the SPL meters insensitivity.

I may be wrong but I am almost sure about that. Unless they are wrong.

--Regards,


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## Doctor X (Apr 3, 2007)

Ovalnut, I _hope_ that you are correct because then my subwoofer levels would be too low in relation to the mains. 

--Regards,


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## OvalNut (Jul 18, 2006)

OK, now I'm totally confused again.  I did say it backwards, should have kept my mouth shut. :duh::surrender:


Tim
:drive:


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## Mark Seaton (Jun 22, 2006)

Vaughan100 said:


> I mean, for those who watch at reference level and calibrate their subwoofers accurately, is this supposed to sound like this ? My room is about 2500 cubic feet.
> 
> I have REW but I lack the cables to try the software out. I've heard of the Velodyne SM1 and people tell me that it's the best tool to use right now. Is it possible that my subwoofer is defective ?
> 
> ...



Hi Vaughn,

The problem lies in the concept of "accurate" calibration. You can only start to define any calibration as accurate if the frequency response of all channels is flat at the listening postion. Once you get the cables to hook up REW you will see just how far from reality that is. :innocent:

Any significant peak in the subwoofer's frequency response at the seat will throw off the meter's reading significantly, leaving that peak near the intended level, but the rest of the range well below. The meter is a very useful point of reference, but until you know the response is reasonably flat, use it as a starting point to adjust from by ear, not an absolute doctrine to be followed.

Two suggestions:

1) Get REW running.

2) Bump the sub level by 3-6dB over your current setting. The meter is very handy if you want to keep the receiver's sub channel setting below 0dB and you need to bump the level with the gain control on the sub. It is easy enough to use the same test signal and re-adjust for a reading of 75-78dB.


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## Doctor X (Apr 3, 2007)

Ovalnut, you are confusing me now. :clap: So are you now suggesting that your previous post was incorrect ?

Must I calibrate to 78 dB relative to the mains or 72 dB ?

--Regards,


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## Doctor X (Apr 3, 2007)

Mark, hi there. Is it common knowledge to calibrate to 75 dB with the sub in order to get a level which is equal to the mains at 75 (taking into account that the FR is never going to be perfectly flat) ?

Or in order to calibrate the sub accurately (as according to the SMPTE) to reference level, must the SPL meter read 72 dB to actually read 75 dB, OR, must the meter read 78 dB for the sub to be in line with the mains ?

Thanks.

--Regards,


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## Mark Seaton (Jun 22, 2006)

Vaughan100 said:


> Mark, hi there. Is it common knowledge to calibrate to 75 dB with the sub in order to get a level which is equal to the mains at 75 (taking into account that the FR is never going to be perfectly flat) ?
> 
> Or in order to calibrate the sub accurately (as according to the SMPTE) to reference level, must the SPL meter read 72 dB to actually read 75 dB, OR, must the meter read 78 dB for the sub to be in line with the mains ?
> 
> ...


Vaughn,

As I stated above, it's a guess as to what the various levels vs. frequency will be without knowing the in-room response. You want your system adjusted to sound good, not to make a standard's committee happy.  Without a resonably flat response, "correct" is very much a matter of perspective. I would have to double check the subwoofer and main speaker test signals used in Avia to be more confident of what should really be observed on the meter... again assuming the in-room response was flat. Sometimes the response will make it read lower, sometimes higher. Don't stress out about it. If you're in the ballpark of the calibration signal and your mains are set, you can easily account for 6dB of variation in both taste and in-room response. 

Your goal is to integrate your subwoofer with your mains in your room. Pay more attention to the proper levels in the main speakers and then use the meter as a guide in setting the subwoofer level.


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## Doctor X (Apr 3, 2007)

I am currently using the internal test tones in my receiver with Radio Shack SPL meter and a flimsy tripod. 

I understand that my frequency response plays a big part in this. I just thought that there was an industry standard way of calibrating speakers at home. Otherwise, why do people over at AVSforum claim that calibrating at 72 dB yields a flat response relative to the main speakers ?

--Regards,


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## brucek (Apr 11, 2006)

> Or in order to calibrate the sub accurately (as according to the SMPTE) to reference level, must the SPL meter read 72 dB to actually read 75 dB, OR, must the meter read 78 dB for the sub to be in line with the mains ?


As Mark implies, it's not meaningful to calibrate with an SPL meter at any level until you have knowledge of the subwoofers response in the room. You need to get REW working.

Short of doing that, the fact is, if you feel your subwoofer is set too low - then turn it up... :blink:

brucek


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## Doctor X (Apr 3, 2007)

Bruce, I downloaded REW but I fear that my onboard sound card is not up to it. Would any creative sound card do or must I fork out more for a very good sound card ?

--Regards,


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## OvalNut (Jul 18, 2006)

Yes, my previous post was incorrect. 

Assuming relatively flat response from your mains and subwoofer (and that's a BIG assumption), then theoretically, using a RS spl meter, you would calibrate your mains to 75db and your sub to 72db in order to calibrate your sub approximately flat to your mains.

Whew!

Tim
:drive:


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## Doctor X (Apr 3, 2007)

Alright. I can't get REW to work for some reason because the software tells me that no output mixers are available (whatever that means) and I lack the cables *but* I attempted to plot the FR down with Ethan Winers test tones.

Further info :

* X-over at 80 hz
* Phase at 360 degrees
* Seating position : 2.8 m from source (I am sitting the short way in my rectangular room)
* Pink noise set to 70-71 dB

I have not measured my FR with phase set to 0. But I noticed more deep bass when set to 360. To be sure I'll measure with both. However I did notice that my mid-bass was severely lacking at 360. At the 0 position I had a much fuller mid-range. I don't know why that is nor do I know which is more accurate.

Here is my frequency response :

hz - dB

20 - 86
21 - 91
22 - 90
23 - 89
24 - 87.6
25 - 85
26 - 84
27 - 84
28 - 82
29 - 82.1
30 - 82.2
31 - 82
32 - 82.1
33 - 83
34 - 84
35 - 85
36 - 87
37 - 89
38 - 88
39 - 85.4
40 - 83
41 - 83.1
42 - 84
43 - 83
44 - 83
45 - 82
46 - 81
47 - 79.2
48 - 75
49 - 73.4
50 - 72
51 - 72
52 - 73
53 - 73
54 - 74
55 - 78
56 - 79
57 - 80
58 - 80
59 - 81
60 - 81
61 - 82
62 - 82
63 - 82
64 - 80.5
65 - 75
66 - 70
67 - 73
68 - 74
69 - 76
70 - 81
71 - 81
72 - 79
73 - 72
74 - 70
75 - 72
76 - 72
77 - 70
78 - 69
79 - 69
80 - 69
81 - 69
82 - 69
83 - 70
84 - 72
85 - 74
86 - 76
87 - 79
88 - 81
89 - 82
90 - 82
91 - 83
92 - 83
93 - 83
94 - 82
95 - 81
96 - 80
97 - 75
98 - 69
99 - 73
100 - 75
101 - 77
102 - 80
103 - 82
104 - 84
105 - 85
106 - 85.3
107 - 86
108 - 85
109 - 86
110 - 86
111 - 86
112 - 87
113 - 88
114 - 88
115 - 87
116 - 84
117 - 84
118 - 84
119 - 84
120 - 83
121 - 83
122 - 82
123 - 82
124 - 82
125 - 82
126 - 81.8
127 - 81.4
128 - 81.6
129 - 82
130 - 82
131 - 81.6
132 - 81.7
133 - 82
134 - 81.7
135 - 81.6
136 - 82
137 - 82
138 - 81
139 - 79
140 - 75
141 - 73
142 - 75
143 - 79
144 - 82
145 - 83.2
146 - 84.1
147 - 85
148 - 85
149 - 85
150 - 85
151 - 85
152 - 85.1
153 - 86.1
154 - 84
155 - 88
156 - 89
157 - 89.1
158 - 89
159 - 89
160 - 89
161 - 90
162 - 91
163 - 91
164 - 92
165 - 93
166 - 94
167 - 95
168 - 95.2
169 - 95.3
170 - 93

Comments will be most appreciated.

Thank you.

--Sincerely,


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## mojomike (Feb 12, 2007)

Vaughan, when you say the phase was at 360, do you mean 180? Because 360 = 0.

The response looks weak in the crossover area (about 69 db) as it does in the area between 65hz and 87 hz (mostly in the low 70 db range). This is a critical area and it is averaging about 20db lower than the upper bass area. I believe you need to run the sub much hotter overall.


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## Doctor X (Apr 3, 2007)

Sorry, I mean't to say 180 deg. So you recommend me to run my subwoofer much hotter overall ?

This "suck out" is the reason why my midbass is so weak ? I mean, it's not as if it's much stronger at 0 deg but it is fuller sounding. I think I will try to chart the response at 0 deg as soon as I have time to do so.

Thanks.

--Regards,


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## adogand6kids (Jul 29, 2006)

Hey,

I guess seeing 90 dB at 20 Hz answers the question, "is my subwoofer defective?"


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## Doctor X (Apr 3, 2007)

Yes, it does.  I increased the bass by 3 dB's and things are sounding better IMO. If I had better positioning and EQ and bass traps, would I be getting louder bass now than before (even after the 3 dB increase) ?

--Regards,


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## mojomike (Feb 12, 2007)

Try this: Average your numbers below the crossover. This is an average output of your sub. Average the numbers above the crossover and compare. Try raisng the level of the sub by the difference and see how that sounds.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Vaughan,

Regarding the RS meter, its response is -1.5 dB below reference from 100 Hz to 50 Hz. Below 50 Hz its response drops progressively steeper, and is down -8 dB at 18 Hz.

So, with your 72 vs. 75 dB, you had it backwards. You should have _increased_ the sub a couple dB to compensate. So basically, what you had was that your subs were 5-6 dB down in relation to the mains (i.e., at 75-75 dB, the subs would have been a couple of dB down). As others have noted, typically you want the subs at least that much hotter than the mains, or even more.



> If I had better positioning and EQ and bass traps, would I be getting louder bass now than before (even after the 3 dB increase) ?


Not necessarily louder, but better. “Louder” is a function of your gain control; “better” is a function of equalization and traps. 

By the way, there’s no reason to take so many readings. 1/12-octave spacing is perfectly adequate. If you need to know what those specific frequencies are, see the response chart in my “PB10-ISD” face off sticky thread. I think there may be a way to enter the values into REW and generate a graph – some of our more software-savy members will know.

Regards,
Wayne


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## Doctor X (Apr 3, 2007)

Wayne, this is a real ear opener for me because all this time I thought I had the sub calibrated in line with the mains. So forgetting about the room response for a second, calibrating my sub to 75 dB is what I should have done in the first place in order to be in line with all the other channels.

In your experience, if you want a 75 dB figure, what must the needle be hitting ? Because with my SPL meter I get a reading which fluctuates between 74 to a maximum of 78 dB. Your thoughts would be appreciated.

Thanks for everyone so far who has posted. I've now learned something new. Ovalnut was indeed correct in his post which he then subsequently edited. Heh. 

I have been pondering over whether I should get the Velodyne SMS-1. Everyone swears by it. I am only a bit hesitant of the resolution that it has, which is 1/6 octave. Is that not enough ? 

Can one use REW in conjunction with SMS-1 to compensate for it's low resolution ?

--Regards,


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## Wayne A. Pflughaupt (Apr 13, 2006)

Vaughan100 said:


> Wayne, this is a real ear opener for me because all this time I thought I had the sub calibrated in line with the mains. So forgetting about the room response for a second, calibrating my sub to 75 dB is what I should have done in the first place in order to be in line with all the other channels.


Nope – remember the meter is 1 .5 dB down (or more, depending on what your hottest bass frequency is). So your sub would have to read about 77 dB to be at the same level as the mains if they’re reading 75 dB. That would be if you wanted flat response - which you probably don't. Most people find that response upwardly tilting (i.e., with the subs louder) sounds more natural. You might want to check the "House curve" sticky thread at our BFD/REW Forum.



> In your experience, if you want a 75 dB figure, what must the needle be hitting ? Because with my SPL meter I get a reading which fluctuates between 74 to a maximum of 78 dB.


I imagine it fluctuates more with the sub that it does the main? I typically use the middle point between the fluctuation points.



> I have been pondering over whether I should get the Velodyne SMS-1. Everyone swears by it. I am only a bit hesitant of the resolution that it has, which is 1/6 octave. Is that not enough ?
> 
> Can one use REW in conjunction with SMS-1 to compensate for it's low resolution ?


I image that 1/6-octave figure corresponds to the readings it “sees,” and not the filters you can set? Yes, you can use REW with any parametric equalizer.

Regards,
Wayne


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## Wayne A. Pflughaupt (Apr 13, 2006)

Oops – Bob just straightened me out in a PM. :blink:

Of course I was going by the well-known correction values for the RS meter, but I forgot that you have to add the corrected value to the meter's _reading_ to get the correct SPL figure. 

So, adding say, 2 dB to a reading of 72 dB would give you the corrected value of 74. That’s the correct way to compensate, not by raising the level of the sub by that amount, like I told you.

Sorry! :dizzy:

Regards,
Wayne


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## OvalNut (Jul 18, 2006)

Welcome to the club Wayne. :whistling:

Tim
:drive:


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## terry j (Jul 31, 2006)

I'm pretty certain you can import the figures you measured and listed into REW and see it graphically. I recall Brucek mentioning it somewhere.

Check the help files, (mine is not running so I can't do it) it could very well be under importing measurements or some such title.

It involves opening notepad and listing those values in there, very similar to how you make up your house curve.

Just had a quick look, it's under importing measurements in the help files.


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## Otto (May 18, 2006)

terry j said:


> I'm pretty certain you can import the figures you measured and listed into REW and see it graphically.


That's right. If you have a .txt file of the form

xx yy
xx yy
xx yy

etc.

Where xx are frequencies and yy are the meter readings, much like was posted above, but with no dashes ( - ) between the numbers.

Simply choose File->ImportMeasurements and select the saved .txt file:









You will then get a message like this:









I'm pretty sure you want to click "YES" here, as you probably measured with C-weighting and didn't apply an inverse curve. However, I admit that I've not run into this in the past...

Since you already have that data, it would be cool to be able to see it in REW, and it's pretty easy to do. Post here if you can't import.


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## brucek (Apr 11, 2006)

> I'm pretty sure you want to click "YES" here


No, the problem here is that it would require a meter or mic that actually tracked a C-Weight to be accurate. None of the meters we use qualify as C-Weight accurate and so we use calibration files to correct them. The Import feature doesn't consider that when loading.

To use this feature you need to manually correct the measurements with the calibration file for your meter manually in a text file and then Import with a 'NO to apply C-Weight' in REW. You would need to measure at frequencies that corresponded to the known calibration file entries.

brucek


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## Otto (May 18, 2006)

Good to know. Thanks, brucek.


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## SteveCallas (Apr 29, 2006)

I'll just echo:

Calibrating the sub and speakers to reference is just a starting point in my opinion. Depending on what master volume you typically watch movies at, the subjective magnitude of the bass will vary a bit because of our hearing sensitivity to low frequencies. Once you are calibrated, fine tune the level by ear. +/-3db can make quite a difference.


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## Guest (Jul 20, 2007)

Hi there,

I apologize for not responding but my ADSL cap has been reached (only 1 gB bandwidth). So if I understand things correctly I was correct all along with the calibration of about 73 dB for a 75 dB level ?

My problem is that my subwoofer should be then capable of reproducing output at 121 dB if all speakers are set to small. But again, watching films at reference (calibrated all speakers to 75 dB and sub 73) my subwoofer does not pressurize the room at those levels. 

In fact I still have headroom to spare. This is why I made the assumption that perhaps my levels have not been correctly setup for accuracy. Perhaps the SPL meter reads low I thought. But I was corrected twice in the thread about that. I just don't understand that watching films at reference level does not give me a room pressurizing effect with my SVS PB10 (at 73 dB). But calibrating higher by 3 -4 dB's does.

My subwoofer is powerful but not that powerful. 121 dB's is not possible from my subwoofer but then why is it that watching the Matrix at reference (on all the bassy scenes) does not seem powerful at all ?

I don't know. That is why I need your advice.

--Regards,


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## salvasol (Oct 31, 2006)

Sorry for this silly question (I'm still learning):help: .... What is reference level????:huh: 

I been trying to figure it out, is that the settings you use in your receiver??? ... L, R, C, etc. set at XXdb?? .... or is that the settings at which the DVD is recorded???? .... Please help me understand.


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## SteveCallas (Apr 29, 2006)

Set your master volume level to 0 and then use test tones to calibrate all speakers to 75db or 85db from your seat depending on the source of the tones and the accompanying instructions. Listening to movies with the master volume at 0 when the speakers are calibrated means each speaker (if it is capable) can be asked to produce up to 105db and the LFE channel up to 115db. That is reference level. When you factor in the redirected bass from the speaker channels and the LFE channel, a subwoofer system can be asked to produce up to ~120db or so.


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## Guest (Jul 21, 2007)

I assume that if one wants to watch a film at the level that the director intended then reference level calibration is needed. 

--Regards,


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## salvasol (Oct 31, 2006)

Thank You for the information :T:T


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## Guest (Oct 11, 2007)

Here's a chart, corrected for RS meter.
Actual reference level targets are marked at each frequency.
ie: if your readings land on these marks, your FR is flat.









Also, here is a 7-up PDF of the chart:
http://www.byrographics.com/audio/FR_chart_3.pdf


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## Ed Mullen (Jul 28, 2006)

Just wanted to make a few comments on this thread:

1) The RS SPL meter has a C-weighted filter and will read 2-3 dB LOW on the typical subwoofer calibration rumble down (which is generally centered in the 35-60 Hz bandwidth). Using Avia, setting the mains to 75 dBC Slow and the subwoofer to 73 dBC Slow (at master volume -10) is a decent starting point for basic channel balancing and system calibration. 

As Mark Seaton correctly stated, unless the FR of the subwoofer is known, the above technique is just that - a good starting point. If there is a peak or a null in the subwoofer response which falls within the bandwidth of the calibration rumble tone, it will obviously affect the calibration level. 

Vaughan had a good start by plotting the FR/SPL levels, but they will be more accurate if the C-weighted correction factors are added to those values to obtain the true/actual SPL at each test frequency. As Wayne and others have stated, the C-weighted CFs start to become meaningful/significant below about 60 Hz and get progressively larger with deeper frequencies. 

Regardless, Vaughan's FR is exhibiting a moderate low/null in the 50-55 Hz region, and is also showing some room gain below about 35 Hz, which will be even more noticable once the C-weighted CFs are added to the data. Overall, it's not a bad looking FR, though.

2) The PB10-NSD is a powerful subwoofer for a 10" driver, but is not capable of Dolby Reference Level playback capability in mid-large size rooms. The amp has very effective limiters which will simply limit/reduce the output levels if the pre-out input voltage exceeds the limiter presets. 

In fact, the subwoofer will actually be _more_ powerful/deep/dynamic if the user keeps the playback levels _below_ the point where limiter activity becomes obvious. Once the subwoofer is being obviously overdriven and the limiter is working almost continuously on heavy/bassy scenes, there will be an obvious lack of impact/dynamic range, which is what Vaughan is noticing on these scenes when attempting to play at DRL.

Vaughan, you need about 12 dB more headroom if you want to play at DRL without overload/limiting/compression. Four (i.e., three more) PB10-NSD would be a good starting point if you want to stick with the same subwoofer. Otherwise look at more powerful models if you want to upgrade.


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## Doctor X (Apr 3, 2007)

Ed, thank you for your advice and insight on my specific problem. I realize that it is illogical to expect a single PB10 to reach reference level. I know that. However, my frequency response has changed since I last posted. Considerably so.

I bought myself the Velodyne SMS-1 parametric EQ/real time analyser and have made a few dramatic adjustments to my FR. I have provided pics of my results elsewhere on this forum but I recently changed a few things. I noted before that after achieving a flat response the bass sounded weak compared to the lumpy FR I had before, with a 4-5 dB increase inbetween 25-30 hz (nonequalized). 

But what I've done would probably be considered as severely limiting dynamics of my subwoofers performance and considerably increasing distortion. Essentially what I did was use two shelving filters to increase output from 15 hz to match output above for a flat response.

I will post before and after FR plots as soon as my camera has fully recharged.  But the fact of the matter was that output below 25 hz went downhill fast. So while output from 25 hz to 80 hz was quite flat (which you will soon see with my pics), everything below that point rolled off considerably. 

So I increased output at 15 hz by around 7-8 dB's. And while it's still around 3-4 dB's short of being flat with the result of the frequency spectrum, it actually has made a massive improvement in terms of perceivable low frequency response. I watched LOTR ROTK, the "heart beat" scene towards the end when Frodo struggles to let go of the ring.

The room was pulsating in a way that it has never done so before. It's almost has if the PB10 came alive after making that adjustment. No port chuffing either. I am actually pretty amazed at that improvement. But the range higher up is not that impressive. Perhaps my subwoofer is just not that linear in the higher bass range.

But I understand what Ed says about compression levels all too well. I learned about the compression issue way back when I first experimented with my SVS last year. Output will increase before the onset of compression and actually decrease, sometimes considerably. In fact, at one point, there was almost no deep bass punch to speak of when my subwoofer reached it's limits.

So it's a little tricky to find the level that provides compression free output levels when all dvd's are mastered at different levels. I guess I am probably going to need an additional PB10 ISD or the new Epik Valor. 

Again, thanks for your observations Ed. I'll post measurements soon and then you can see what I've done.

--Regards,


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## Doctor X (Apr 3, 2007)

Here are both graphs. 

Unequalized :










Equalized :










Discuss.

--Regards,


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## Josuah (Apr 26, 2006)

Also, you've got an 8dB difference due to a peak at 22Hz (probably room gain). That means if you just calibrate using a full-spectrum noise signal, most of the time you're running -8dB. You should try to address that bump by adjusting placement, room treatments, or a parametric filter, and then calibrate.


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## Doctor X (Apr 3, 2007)

But isn't the net result the same ? I got the peaks down and increased the upper bass stuff and got a relatively flat response. Maybe I'm not understanding you.

I also don't have a lot of flexibility as far as subwoofer placement is concerned.

--Regards,


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## thxgoon (Feb 23, 2007)

IMO your frequency response looks pretty good. Why do you feel the bass is lacking?

In addition to things said above, try using a source other than your receiver's test tones for setting the levels. Something like Avia or Video Essentials or any THX dvd with optimizer on it. Sometimes what comes out of the digital decoder and what your receiver generates are not the same. I have this exact problem with my receiver and have to run the sub at -7 to get 'accurate' response.


In the end though, the 'accurate' setting is only a guideline. Adjust it until you like it.:nerd:


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## Josuah (Apr 26, 2006)

Vaughan100 said:


> But isn't the net result the same ? I got the peaks down and increased the upper bass stuff and got a relatively flat response. Maybe I'm not understanding you.


If you run noise out your subwoofer, to level match with your mains, and there is a peak that is +8dB from the rest of the frequency response, then you're level matching the +8dB point, not the overall response. If you've gotten rid of the peak, then no worries. I didn't see that you'd already cut the peak somehow.


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## Doctor X (Apr 3, 2007)

Yeah, I cut that peak down to size.  I'm still using the old Velodyne software, subsonic filter set to 15 hz. I imagine if I set it to 5 hz (latest firmware update but Curt tells me that one will be able to disable the high pass filter completely soon) that my output would increase quite a bit at 15 hz.

Now for those who know and understand the SMS-1. If I keep the SMS-1 in the loop in my system, the much vaunted "rolloff" will take place from 22 hz and below even if I set subsonic filter to 5 hz. If I disable EQ but keep SMS-1 on, does the EQ roll off still effect the system, or only once response has been equalized ?

I'm looking forward to removing the high pass filter altogether. 

--Regards,


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## thxgoon (Feb 23, 2007)

Asking a 10" sub to do 15hz is asking a lot. Asking it to do it at reference with a boost provided by the SMS is asking even more. Your sub has a limiter on it and if it's exceeding its output capabilities at 15hz, it is going to cut back to a safe level, taking all of the other frequencies with it. Are you really listening at reference a lot? If so I think you should be calibrating differently.


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## thxgoon (Feb 23, 2007)

Is the PB 10 tuning adjustable like the others? From your graph I'd say that it looks like it's tuned near 25hz. Bumping levels below this tuning point also greatly increases the risk of bottoming the woofer and causing damage.

That aside, the manual for your sub recommends setting the sub 1-3db hot. Give SVS a call on this matter, they have GREAT customer service.


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## Josuah (Apr 26, 2006)

I don't know if the SMS-1 still results in roll off when it's set to do nothing. IIRC, there are also measurements indicating excessive distortion on the unbalanced inputs if the input signal voltage is high (in other words, better to up the subwoofer's gain and decrease the processor/receiver's subwoofer level).

I ended up getting rid of the SMS-1 because of the roll off it was having below 20Hz.


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## Doctor X (Apr 3, 2007)

No, I'm definitely not listening at reference. My listening preference has my MV between -15 to -7 from reference. My way of thinking is that once the subsonic limiter is disabled on the SMS-1, I can then cut back on the 15 hz boosting because the high pass filter is not robbing me of energy down that low.

So I can create a flatter response with less effort. But is it really possible that my Yamaha test tones are inaccurate compared to Avia software ? I currently have Video Essentials but I've never used the test tones on the disk because I've heard that it is very unstable to use.

--Regards,


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## Josuah (Apr 26, 2006)

I don't use full spectrum tones for calibration anymore. It's too easy to end up calibrating against a peak. And you have to try and remember if there are quirks in the test tones on those discs. I use REW and a mic for the subs and the speakers.


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## tdamocles (Sep 23, 2006)

What receiver are you using? If you have the AVIA calibration dvd try the 5.1 channel sweep with LFE just to see if the LFE output is correct. Maybe the LFE isn't being managed correctly?


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## imbeaujp (Oct 20, 2007)

Hello, the frequency response seems to be ok as shown on the graphics.

I do use RS SPL to calibrate mains and surrounds speakers at 75bd ref. But for the sub I adjust the level manualy. Depending on the listening volume, and the movie, you have to change the sub level. Of course there is a base setting, but it depends so much on the movie and the listening level that it definitively can not be a permanent setting. 

JP


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## Doctor X (Apr 3, 2007)

Josuah, because my room response is fairly flat to 20 hz, I wouldn't be calibrating against a peak. It's calibrating against a flat response. 

Would using a test disk like Avia help at getting more accurate warble test tones compared to my AVR ? I don't think it could though.

--Regards,


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## Doctor X (Apr 3, 2007)

tdamocles, my LFE is set to it's highest level in my AVR. I assume that _that_ is the correct setting. Reducing the LFE level will only serve to reduce the level in the LFE track. But how would I know if the LFE output is more or less accurate than my AVR ? Maybe my AVR is more accurate than Avia ? 

--Regards,


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## tdamocles (Sep 23, 2006)

Vaughan100 said:


> tdamocles, my LFE is set to it's highest level in my AVR. I assume that _that_ is the correct setting. Reducing the LFE level will only serve to reduce the level in the LFE track. But how would I know if the LFE output is more or less accurate than my AVR ? Maybe my AVR is more accurate than Avia ?
> 
> --Regards,



What receiver are you working with?


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## Doctor X (Apr 3, 2007)

I'm using the Yamaha RXV-450. It's an old-ish receiver, probably around 4-5 years old.

--Regards,


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## tdamocles (Sep 23, 2006)

What is your SP LFE set at in your menu setup? Sub level and LFE level are two different things. Avia can send a test signal as a .1(LFE.... the .1 is the LFE channel) signal. The 5.1 channel sweep with LFE will check to see if the LFE is loud enough.


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## Doctor X (Apr 3, 2007)

I'm well aware that the sub level and LFE level are two completely seperate things.  My sub level is set to -9 (from +10 to -10) and my LFE is set to 0 (maximum, from 0 to -10).

--Regards,


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## Josuah (Apr 26, 2006)

Since you already know your frequency response is flat, just send some white noise out and calibrate that way.


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## Doctor X (Apr 3, 2007)

Joshuah, is it normal to calibrate using white noise ? I assume I've got a white noise test tone on my Video Essentials disk.  I haven't used the audio portion of this disk since I bought it. Mainly for video calibration.

Heh.

--Regards,


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## Josuah (Apr 26, 2006)

Well, usually the signal is pink noise. But that decreases output as the frequency increases. I don't recall what's on the Video Essentials disk as I always calibrate using a computer now.


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## Doctor X (Apr 3, 2007)

Do you find calibrating levels with REW to be more accurate ? Are the levels higher or lower than using a normal SPL meter ? Have you compared the results from both ?

Thanks !

PS I really would like to use REW one day but my sound card is not up to the job. I'm just using onboard sound and it's terribly difficult to get it to work with REW.

--Regards,


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## SteveCallas (Apr 29, 2006)

Boosting a range below tuning on a ported sub is a definite no no. That PB10 is tuned no lower than 18hz, and you're using boosting at 15hz......yeah, just think about that for a second :thumbsdown: You're stressing that driver way more than it needs to be much more often than it needs to be. If it works for you, more power to you I guess, but you really should have bought a different subwoofer to begin with, and it shouldn't have a 10"er.


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## Doctor X (Apr 3, 2007)

SteveCallas said:


> You're stressing that driver way more than it needs to be much more often than it needs to be.


The driver is only going to be stressed out more than it needs to be if there is content that can be voiced but I don't understand the second part of your statement. 

Consider this. Consider that the SMS-1 is already rolling off the bass at 6 dB's per octave and this starts at around 20 hz (with subsonic limiter set to 15 hz). So I'm down more than I should be which means that the driver isn't going to be working as hard as it _would_ have had I not had the subsonic limiter engaged in the first place.



> If it works for you, more power to you I guess, but you really should have bought a different subwoofer to begin with, and it shouldn't have a 10"er.


I was thinking of buying another PB10 or an Epik Valor but the Valor is not an option so I guess another PB10 is it. And hey, my subwoofer is no slouch for a 10"er !

--Regards,


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## SteveCallas (Apr 29, 2006)

Yes, the SMS restricts your low end, but the boosting you dialed up is more than 6db / octave. Below tuning, excursion skyrockets because the port is actually working against the driver. With a tuning as high as ~18hz, it leaves a lot of room for potential bad things to happen, and this is why SVS uses a highpass filter. You are working your way around the filter, which is meant to protect the driver, by forcing the driver to work even harder below tuning. So now, anytime something around or below tuning gets sent to your sub, it's being stressed much more than it should be, and while the distortion in frequencies that low may not not be audible, it's going to interfere with the cleanliness of reproduction of higher frequencies as well, simply because the driver is working so hard.

The PB10 may be a great 10" sub, but it's still just a 10" and can only do so much. It wasn't meant to give you solid extension to 15hz - left natural, I believe it maxes out at ~98db levels throughout most of its range.


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## Doctor X (Apr 3, 2007)

Unfortunately I don't have the funds available to get the new Epik Conquest or the big ED design. But the SVS PB10 is right up my alley )) and it's relatively inexpensive.

Would that not be a option ? I guess that the best I can do is to buy another PB10 which would give me an additional 6 dB's across the board when co-locating both (and I will co-locate). 

My listening levels are never below -5 from reference, so it's possible that dual PB10's will be compression free (if calibrated to 73 dB's for sub) down to a *MV* of -7 ?

--Regards,


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## SteveCallas (Apr 29, 2006)

Not likely. Calibrated LFE channel can get up to 115db at reference and then you have to factor in the redirected bass from each speaker, bringing it up to ~118db. If your sub is calibrated 2db low, and max output is ~98db per sub, and you get the full 6db from collocation, that would theoretically mean -12 would be the loudest you could play while trying to stay compression free (assuming the dvd soundtrack isn't hot).


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## thxgoon (Feb 23, 2007)

Vaughan100 said:


> My listening levels are never below -5 from reference, so it's possible that dual PB10's will be compression free (if calibrated to 73 dB's for sub) down to a *MV* of -7 ?
> 
> --Regards,


I thought you said you were not listening at reference levels. Are you referring to listening at levels higher than -5 below reference all of the time? If so that is quite loud and your sub will not be able to handle that down deep. I think you should reconsider your calibration and perhaps roll the sub off at lower frequencies. Doing that would give the sub more dynamic range overall and while you won't get room shaking low bass, you would have sufficient bass above 30hz and might be less underwhelming.


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## Josuah (Apr 26, 2006)

Vaughan100 said:


> Do you find calibrating levels with REW to be more accurate ? Are the levels higher or lower than using a normal SPL meter ? Have you compared the results from both ?


It's more accurate because any room is naturally going to result in significant differences in SPL at different frequencies. I've often read that people find a range of 10dB to be quite good for a room, even with speakers that are anechoicly flat. If you can see the actual response, you can eyeball what you think is the real SPL line and adjust accordingly.

You can usually buy a USB sound/mic device off eBay for around $60 or something. That should be better than your computer's sound card.


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## Doctor X (Apr 3, 2007)

Speaking of "calibrating", I was almost about to pull the trigger on the Galaxy CM-140 SPL meter thinking that it wouldn't read low when using the subwoofer warble tone in the AVR to set levels. 

But apparently it reads just as low as the Radioshack meter (which I currently have). That is a disappointment. 

So then according to you, Steve, I might require 3 PB10's to reach an MV of -7 compression free ? That's a lot of sub to have in one room ! 

--Regards,


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## Doctor X (Apr 3, 2007)

Joshuah, thanks for the reply. This goes to everyone who has posted thus far. I really appreciate the advice and suggestions given.

--Regards,


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## SteveCallas (Apr 29, 2006)

Not likely. You only stand to potentially gain 6db when you double the displacement - since you would have two subs, you would need four to get another 6db, not three. The third sub would get you ~3.5db best case scenario. 

You are better off ditching the 10"s and going with a 15" or 18" in my opinion. Four $400 subs + shipping can pay for one much better sub.


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## dieselpower1966 (Nov 26, 2007)

Question,
my speakers frequency is 35-26hz for my front left & right, my center is rated 40-26hz. I have my Onkyo set up with double bass on and the front mains running full band. (I know that these are not full band speakers, however this is the setup that Onkyo suggest I try) my subs crossover is set at 80 hz and the center is set at 80hz as well, on the Onkyo. the bass sounds deep and fairly smooth and rattles the ceiling fan. but I'm curious if this set up is correct? my spl meter says that all speakers are at 75 spl. and my sub at 78. I also have the LFE gain in my Onkyo set at + 10.
here's the question. Any comments? suggestions? Tips? Can I measure the frequency or anything else with my radio shack digital spl meter? 
Thanks


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## Sonnie (Apr 11, 2006)

Vaughan100 said:


> Speaking of "calibrating", I was almost about to pull the trigger on the Galaxy CM-140 SPL meter thinking that it wouldn't read low when using the subwoofer warble tone in the AVR to set levels.
> 
> But apparently it reads just as low as the Radioshack meter (which I currently have). That is a disappointment.


I would say the CM-140 is considerably better and by far the more consistent of any we have measured.

CM-140
7.00	-16.09
8.00	-13.77
9.00	-11.90
10.00	-10.62
11.00	-9.86
12.00	-9.03
13.00	-8.40
14.00	-7.95
15.00	-7.40
16.00	-7.04
17.00	-6.56
18.00	-6.28
19.00	-5.90
20.00	-5.49

33-2055 or 4050
7.00	-27.00
8.00	-22.55
9.00	-19.37
10.00	-16.91
11.00	-15.27
12.00	-13.74
13.00	-12.42
14.00	-11.33
15.00	-10.28
16.00	-9.28
17.00	-8.53
18.00	-7.86
19.00	-7.12
20.00	-6.56


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## dieselpower1966 (Nov 26, 2007)

sorry but those numbers tell me absolutely nothing, and didn't answer any of my questions.


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## brucek (Apr 11, 2006)

> sorry but those numbers tell me absolutely nothing, and didn't answer any of my questions


I think Sonnies answer above was for the question that Vaughan asked.

With regards to your question, the answer of whether you can use the SPL meter to measure anything else, would be yes.

At present you are simply measuring SPL _level_ from a receiver generated pink noise. This is a good start, but doesn't address the various peaks and valleys that might exist over and outside the pink noise bandwidth.

If you wish to do a basic measurement of various frequencies using sinewave test tones that you burn on and play on a CD, you can download some tones here.

You can also plot the results of that tone test on an excel spreadsheet obtained from that same download page referenced above. The spreadsheet automatically compensates for any inaccuracies of the RadioShack meter. It tends to become inaccurate at low frequencies..

brucek


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## Doctor X (Apr 3, 2007)

Sonnie, but if we take the Radioshack SPL meter and the CM140 and calibrate to a 75 dB level, both meters are going to be inaccurate to the same degree.

No improvement whatsoever for calibrating with pink noise. But if you measure your in room frequency response then the CM140 is definitely more accurate. For what I need it for, right now, it seems that it won't offer any advantage whatsoever (according to Brucek). 

Which is disappointing as I was hoping for a more accurate way of getting the levels right without having a laptop at the ready.  Now that doesn't mean that I won't use a laptop with REW but I was hoping for a simple method of getting the correct levels without having to add additional dB figures to the reading to get a level figure.

Cheers.

--Regards,


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## warpdrive (May 6, 2007)

I think calibrating for accuracy is a noble thing, but in reality, it's a bit overrated due to the differences in response at different listening locations. I mean, there are people who are trying to use 1/12 octave sweeps and calibrating perfectly flat for an particular listening location, but even if you move your head 6 inches, all that accuracy is lost.

Also for anything less than reference, you MUST run your sub a bit hot otherwise you just aren't getting the bass that sounds realistic. I run mine 3dB hot below 50Hz at 5-10 dB below reference, and it sounds best too me that way


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## jdeanmc (Aug 26, 2008)

SteveCallas said:


> Set your master volume level to 0 and then use test tones to calibrate all speakers to 75db or 85db from your seat depending on the source of the tones and the accompanying instructions. Listening to movies with the master volume at 0 when the speakers are calibrated means each speaker (if it is capable) can be asked to produce up to 105db and the LFE channel up to 115db. That is reference level. When you factor in the redirected bass from the speaker channels and the LFE channel, a subwoofer system can be asked to produce up to ~120db or so.


Steve,
I "balance"my speakers by going into the test tones of the receiver,turn up the volume until the left front reads at 75 db then set all the other speakers with the volume in this "fixed"position.this usually ends up at about -13 to 15 on the master volume.Is this not correct?will i notice improvements by doing the balance at 0 on the master volume?
BTW i set the subs using the hsu test disk not the receivers test tones but i still start with the receiver at the same -13 to -15 db.
Thanks
Dean


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## Doctor X (Apr 3, 2007)

My problems have been sorted. I no longer have the SVS PB10 ISD but I know what the issue was. Gain levels. The gain was set too low. Even though the overall SPL level read between 72-73 dB's. I effectively reached a compression state where my *MV* levels increased but the sub levels simply did not give a corresponding level increase.

This severely affected dynamic peaks. This is why I never could understand why after equalizing my subwoofer response I still couldn't get my output levels to increase as my MV level went up. I mean, if anything, I'll have a lot more headroom, I cut at least several peaks down by several dB's so there is no reason why I should be experiencing compression at all. 

So with a very low gain level I thought perhaps I should increase the subwoofer level which was also low (again, the overall SPL figure at the seats with the subwoofer test tone hit 73-74 dB's) and the bass increased but dynamic peaks were again highly compressed. Please take note that I did disable DRC in both the receiver and dvd player so that was not the issue.

But whenever there was a big bass hit; any loud explosion with a large dynamic swing caused the subwoofer to stop getting louder, even as my MV approached reference, the bass levels sounded anemic. 

However once I turned the gain levels higher and lowered my subwoofer level this all changed. Completely. Now we're talking ! Keep in mind that the overall SPL level at the seats was _still_ 72-73 dB's. Yet now I can feel the bass and the bass levels increase as my MV increases with no compression that I can tell.

I can't believe all this time that that was the issue. So my thoughts on calibration have completely changed. I was initially underwhelmed calibrating to 72-73 dB's which is considered "accurate" but the entire time I based my disappointment on a symptom that was completely unrelated to the topic.

I just thought I would let you all know that I am happy with the results now. The thread topic for me is not a true reflection of how I feel but I'm glad and appreciate all the responses I got and feedback from others.

Again thanks.

Regards,


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## salvasol (Oct 31, 2006)

jdeanmc said:


> I "balance"my speakers by going into the test tones of the receiver,turn up the volume until the left front reads at 75 db then set all the other speakers with the volume in this "fixed"position.this usually ends up at about -13 to 15 on the master volume.Is this not correct?will i notice improvements by doing the balance at 0 on the master volume?
> BTW i set the subs using the hsu test disk not the receivers test tones but i still start with the receiver at the same -13 to -15 db...


Dean ...I'm sure you're using an external amp, Right??? (at least to power the fronts).

There's nothing wrong using -13 to -15 on the master volume (mine are set at -7.5) :yes:

You can also use any DVD with the THX optimizer to calibrate everything (or better if you have DVE, AVIA, etc.)...I'm not sure that you'll get the correct level when calibrating with two different sources (internal test tones for the speakers and HSU test disc for the sub (I'm sure they have different volumes) ... I think it will be better using all test tones from the same source) :yes:


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## Prof. (Oct 20, 2006)

Vaughan100 said:


> However once I turned the gain levels higher and lowered my subwoofer level this all changed.


Are you referring to the individual volume trims on the AVR..when you say gain levels.?

I've just recently increased my trim levels and lowered the sub gain and achieved a similar improvement in the low frenquency dynamics..:T

EDIT..I've just remembered that you have a seperate amp. so I guess you're reffering to the gain on the amp..


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## thxgoon (Feb 23, 2007)

Prof. said:


> I've just recently increased my trim levels and lowered the sub gain and achieved a similar improvement in the low frenquency dynamics..:T


Interesting. I've never thought of this but it makes sense. I'll have to give it a whirl


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## Doctor X (Apr 3, 2007)

The thing is, I initially thought that it wouldn't necessarily matter which way you calibrate, either using a high gain level at the subwoofer amp and a low subwoofer level (or vice-verse) to reach the target SPL at the seats.

When I talk about the gain levels I'm talking about the gain knob at the back of the subwoofer. Although I have a vastly more potent subwoofer system now the same thing happened. So it wasn't necessarily a case where the PB10 was at fault because my demands are not too high. I don't run the subwoofers 4-5 dB's hot.

I calibrate flat and equalize flat which means I really shouldn't have issues running at almost any level (down to reference). So for those experiencing similar symptoms, turn the gain knob up a little and recalibrate. 

Regards,


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## maikeldepotter (Jan 10, 2008)

Vaughan100 said:


> The thing is, I initially thought that it wouldn't necessarily matter which way you calibrate, either using a high gain level at the subwoofer amp and a low subwoofer level (or vice-verse) to reach the target SPL at the seats.
> 
> When I talk about the gain levels I'm talking about the gain knob at the back of the subwoofer. Although I have a vastly more potent subwoofer system now the same thing happened. So it wasn't necessarily a case where the PB10 was at fault because my demands are not too high. I don't run the subwoofers 4-5 dB's hot.
> 
> ...


This is really intersting stuff! Could you indicate which position of the subwoofer gain control gives you the most satisfying bass dynamics? Is that at 10, 20, or 30% of the full range? Just to have a start at tweaking my own system...


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## Doctor X (Apr 3, 2007)

Hi Maikel,

I first had my gain knob turned to 25%. Now I know this is low. But I mean, for those who have multiple subwoofers how else are they going to calibrate ? You will lower the gain levels due to the effects of co-location and calibrate to a lower level unless you want to run the subwoofers hot in which case you won't.

My subwoofer level was around -2 from a range of -10 to +10. Please understand that I have a level of power that is at least 3-4 times the output of a single PB10 ISD and the very _same_ effects occured with my new setup. With my new setup I turned the gain to around 20%, subwoofer level at around -5. I do have the SMS-1 still so that was connected to the system.

Same problem and I was pulling my hair out at this stage. I contacted Mark Seaton, I contacted a number of people that might be able to ascertain the cause of my problem. Prior to this I trouble-shooted and performed just about every check there was not thinking that my gain levels were the cause of the issue.

Even Mark Seaton said that perhaps I needed to increase my subwoofer levels because 73 dB's was not that high which might account for the weak bass. Of course that wasn't the issue, it wasn't a level issue it was a gain issue. I mean, I'm not a novice on this stuff, I do understand a great deal and I work in the industry, still, I couldn't put my finger on the issue.

So, in frustration, I just decided, what the , let me turn the gain knob to 40%. Watching the Matrix Revolutions Neo/Smith fight at the end was intense ! I got hit in the chest so violently I was literally put in state of shock. So I recalibrated my levels to read the exact same SPL figure (72-73 dB's using the Radio Shack SPL meter) and my room pressurizes as it should. No compression effects whatsoever. 

Problem solved. Just goes to show you how much of a difference it can make because it was literally night and day. 

Regards,


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## jdeanmc (Aug 26, 2008)

I am actually running everything through my avr yamaha rxv1800.
I will try calibrating using avia or sound and vision.i think i have both,this makes sense,i havent thought about needing to use the same source.I think that may be my problem(i hope!)the fronts seem to have alot more volume to them than the subs when everything is set at 75 db and even with subs set at 82-84 db.
I will try this
Thanks


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## Doctor X (Apr 3, 2007)

What subwoofers do you have ? How have you set up them ? Are your speakers set to small/large ? 

Regards,


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## jdeanmc (Aug 26, 2008)

I have the Hsu 3.3ho with turbo (on right side wall about 1/3 way from front and back wall)and the Hsu Mbm12(directly behind sofa)Yamaha Rxv1800 receiver and klipsch rf3's set to small and ive moved the rec crossover from 80-90-100-110-120
I turn on the rec test tones and set all speakers to 75 hz,then with the hsu calibration disc set the subwoofer level(which is currently about 82-84 db).both subs are connected via y cable from sub out.
I set the 3.3 first with its xover at 50 hz and "in"then turn off 3.3 and set mbm with xover "out"then turn both subs on,set xover on3.3 to "in" and the mbm xover to "out"and check the level with both subs on.i have the chart for the correction tables for the radio Shack spl meter.
Does anyone see a problem with this?
Thanks
Dean


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## bone215 (Dec 15, 2006)

I calibrate to flat using instruments like spl meter and test tones, then, I increase sub volume to my taste. 
My ears have to enjoy the system, not my spl meter.


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## jdeanmc (Aug 26, 2008)

Well Now im getting somewhere!!!!!!!
I dont know exactly what made the big difference,in hindsight i guess i should have tried these one at a time but...
1.I set all speakers spl with the same disc,sound and vision av essentials,i think.
2.I turned all speaker levels to far left( min setting) ,then turned the avr to -5.then turned up speaker levels until i got to 75 db.i did run the subs to about 80 db.(i calibrated the mbm and 3.3 ho up as per cyberbri's post)
Now my speakers levels are +2.5 to +5.5 in the avr and i set the sub to -5 and got them to 80 db using the gain on subs.
NOW I GOT BASS,holy smokes!!!everything sounds much fuller,richer,i can even tell a big difference in dialog,it sounds like someones standing right in front of you as opposed to a recording,i dragged my daughter downstairs to watch ratatouille AGAIN and she about jumped off the sofa when the lightening struck.I then dragged my wife downstairs sunday night and though i have about run her crazy with all this,she too couldnt believe the difference,she said the same scene about gave her a heart attack!!
I again dont know what had the biggest impact but im definitely now getting what i paid for (sub wise)
My problem all along has been my mains were so much louder than my subs, i think, i just couldn't get to the root of the problem.i guess it was do to setting mains with avr test tones and then subs with hsu disc?But again now everything is balanced to a point where it sounds awesome.I still will get rew up and going and then ill be back with more questions im sure but for now im going to watch some movies.
Thanks so much to bsoko2 and cyberbri for all your answers and replies(pete at hsu also)as well as everyone else thats chimed in to my post after post after post.
Thanks
Dean


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## salvasol (Oct 31, 2006)

jdeanmc said:


> ...NOW I GOT BASS,holy smokes!!!everything sounds much fuller,richer,i can even tell a big difference in dialog,it sounds like someones standing right in front of you as opposed to a recording


I'm glad you're happy with the changes you made ...:yes: ...that's why we're here, to help each other :T


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## Prof. (Oct 20, 2006)

jdeanmc said:


> 2.I turned all speaker levels to far left( min setting) ,then turned the avr to -5


Do you mean you set the LFE on the AVR at -5.?

What O'clock position on the sub is the gain setting.?


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## jdeanmc (Aug 26, 2008)

i set the master volume on the avr to -5.Before i ran the test tones and set all spekaer levels to 75 db and this ended up with my master volume at about -30 to get 75 db. 
Currently the lfe level is at -3 and the subs gains are about 11 oclock on the ho and the mbm is about 12 oclock.
Dean


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## salvasol (Oct 31, 2006)

jdeanmc said:


> i set the master volume on the avr to -5.Before i ran the test tones and set all spekaer levels to 75 db and this ended up with my master volume at about -30 to get 75 db...


I'm a little :dizzy: ... if you set your master volume at -5.0db, and ran the test tones and at the same time you were adjusting each speaker level to get 75db ...How did you end up with -30 to get 75db????

Or do you mean, that you now use your master volume at -30.0???

This is what you posted before ...


> 2.I turned all speaker levels to far left( min setting) ,then turned the avr to -5.then turned up speaker levels until i got to 75 db.i did run the subs to about 80 db.(i calibrated the mbm and 3.3 ho up as per cyberbri's post)
> Now my speakers levels are +2.5 to +5.5 in the avr and i set the sub to -5 and got them to 80 db using the gain on subs.


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## Prof. (Oct 20, 2006)

salvasol said:


> Or do you mean, that you now use your master volume at -30.0???


I think that's what he's saying..but -30 on the master volume seems very low to me..
I would have thought that, the higher the level on the MV..the greater the dynamics..
Maybe I'm wrong..:huh:


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## salvasol (Oct 31, 2006)

Prof. said:


> I think that's what he's saying..but -30 on the master volume seems very low to me.. I would have thought that, the higher the level on the MV..the greater the dynamics..
> Maybe I'm wrong..:huh:


I think it will depend on the source :yes:

I calibrated my system and the reference is @ -7.5db ... and when I watch a DVD I set my master between -25.0db and -20.0db ...watching OTA -30.0db to -25.0db :hide:

We'll see what he say ....:bigsmile:


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## Prof. (Oct 20, 2006)

i'm at the other end of the scale...
Because my room is so dead, I calibrate at 00 reference on the MV..to give me 75dB.across the fronts..
When playing a DVD, the volume is between -4.0 and -8.0..:bigsmile:


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## jdeanmc (Aug 26, 2008)

Sorry for the delay guys.I've been watching movies!!!!!!!!(and election results)
anyway,what im trying to say is that before i simply ran test tones,the first speaker to come up was front left so i adjusted the speaker level(in setup)to get 75 db on spl meter,then went to the next speaker and so on,so when i had all speaker levels matched at 75 db my master volume ended up at around -30 db!!!!i then plugged in the hsu test disc ran it on the 250hz test to make sure i was at 75db on mains,then ran tones from 16 to 125 hz to get subs calibrated.I never was happy with the outcome(i think your right about lack off dynamics with mv that low,also i had no bass even though i had everything calibrated,i thought.
Now i cut all speaker levels completely to lowest position(in setup),then turned up mv on avr to -5,then brought speaker levels(again in setup)up until i got 75 db and subs about 80 db leaving mv(on avr)at -5db.also i never ran the receivers test tones,i set everything with the same source.(the av essentials dvd)and the difference is night and day!!!!!im blown away.now im wanting to run the ypao to adjust the eq but im almost scared to mess with it!
Dean
p.s. my mains are klipsch rf3ii's-98 db per watt,very sensitive,maybe thats why when i used the test tones,i ended up at-30 db on receiver and speaker levels at +8 to +9,now im at -5 on the rec.with speaker levels at +2.5 to +4.5


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## jdeanmc (Aug 26, 2008)

salvasol said:


> I'm a little :dizzy: ... if you set your master volume at -5.0db, and ran the test tones and at the same time you were adjusting each speaker level to get 75db ...How did you end up with -30 to get 75db????
> 
> Or do you mean, that you now use your master volume at -30.0???
> 
> This is what you posted before ...


I guess i meant that BEFORE i changed the way i calibrated everything i ended up with -30db on the receiver(if i just went into test tones menu and adjusted speaker levels)without touching mv on the avr.
now i adjusted the avr mv to -5db FIRST and then went into test tone menu and brought speaker levels DOWN to get to 75 db.Initially with the speaker levels at +8.0 to +8.5 db the avr mv would be at about -30.now setting avr mv first to -5db i set speaker levels to +2.5 to +5.5 db and subs are at -5 to 0.0 db on the avr.i had read that it didnt matter,if it was calibrated at -30 it would still be calibrated at-5 db on mv,but this difference is huge. 
Dean


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## maikeldepotter (Jan 10, 2008)

jdeanmc said:


> Sorry for the delay guys.I've been watching movies!!!!!!!!(and election results)
> anyway,what im trying to say is that before i simply ran test tones,the first speaker to come up was front left so i adjusted the speaker level(in setup)to get 75 db on spl meter,then went to the next speaker and so on,so when i had all speaker levels matched at 75 db my master volume ended up at around -30 db!!!!i then plugged in the hsu test disc ran it on the 250hz test to make sure i was at 75db on mains,then ran tones from 16 to 125 hz to get subs calibrated.I never was happy with the outcome(i think your right about lack off dynamics with mv that low,also i had no bass even though i had everything calibrated,i thought.
> Now i cut all speaker levels completely to lowest position(in setup),then turned up mv on avr to -5,then brought speaker levels(again in setup)up until i got 75 db and subs about 80 db leaving mv(on avr)at -5db.also i never ran the receivers test tones,i set everything with the same source.(the av essentials dvd)and the difference is night and day!!!!!im blown away.now im wanting to run the ypao to adjust the eq but im almost scared to mess with it!
> Dean
> p.s. my mains are klipsch rf3ii's-98 db per watt,very sensitive,maybe thats why when i used the test tones,i ended up at-30 db on receiver and speaker levels at +8 to +9,now im at -5 on the rec.with speaker levels at +2.5 to +4.5


Wait a minute! Are you actually saying that initially you set the left speaker to 75 dB using the set-up menu at a certain fixed master volume position, and from there on you set the remaining speakers to 75 dB using the master volume control, and not the set-up menu? :unbelievable:


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## GregBe (Apr 20, 2006)

jdeanmc said:


> I guess i meant that BEFORE i changed the way i calibrated everything i ended up with -30db on the receiver(if i just went into test tones menu and adjusted speaker levels)without touching mv on the avr.
> now i adjusted the avr mv to -5db FIRST and then went into test tone menu and brought speaker levels DOWN to get to 75 db.Initially with the speaker levels at +8.0 to +8.5 db the avr mv would be at about -30.now setting avr mv first to -5db i set speaker levels to +2.5 to +5.5 db and subs are at -5 to 0.0 db on the avr.i had read that it didnt matter,if it was calibrated at -30 it would still be calibrated at-5 db on mv,but this difference is huge.
> Dean


You may want to take that even further, and raise the master volume even further when calibrating and get it to 0dB. That way you have a easy gauge how far away you are from reference level when you watch (reference level being 0 dB in this case). That would bring the channel level of your speakers down to 0 or negative. In the grand scheme of things it really shouldn't matter, as long as it is calibrated, but some say having your channel levels at 0 or lower helps with distortion. I personally like having my reference level at 0 dB, so when if I am watching at -10dB, I know I am 10 dB below reference.


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## jdeanmc (Aug 26, 2008)

maikeldepotter said:


> Wait a minute! Are you actually saying that initially you set the left speaker to 75 dB using the set-up menu at a certain fixed master volume position, and from there on you set the remaining speakers to 75 dB using the master volume control, and not the set-up menu? :unbelievable:


no,not at all.all speakers were set the same,in the setup menu without ever touching the master volume.


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## Doctor X (Apr 3, 2007)

Guys,

I'm going to need some help from those with experience with the SMS-1.  So I'm not done yet. I'm only getting started.

Let me briefly explain what I've done. I have calibrated my first subwoofer at a set gain to 71-72 dB's. Turn that subwoofer off and turn on second subwoofer. I repeated and set the gain to a level which gives me 71-72 dB's.

The overall level when both subwoofers are on ends up at 75-76 dB's (with the needle sometimes hovering a bit above that). I then took my subwoofer level and reduced it so that the overall level with both subwoofers on equals 73 dB's.

My first subwoofer is positioned almost in a corner. Now if I turn on the first sub and look at the frequency response at the seats using the on screen display it shows a lot of room gain down to 20 hz with a major depression in between 50-65 hz. No amount of phase control or distance settings can save me on that one.

If I use the SMS-1 to correct for this then I end up flattening output down to 20 hz (by 4 dB's), and I end up increasing output by 6 dB's to give me as flat a response as possible within that 50-65 Hz range. Yes I am well aware that I am using up some headroom here.

Now I turn that sub off and put on the second sub just to have a look and see what has happened. With preset 6 engaged (no EQ) in the second position I have very little bass from 20 hz up to 40 hz but then from 40 hz and above I get huge peaks.

Let me show you what I'm talking about :

First sub positioned in corner without EQ :

http://img386.imageshack.us/my.php?image=dsc02299rg2.jpg

Second subwoofer (first subwoofer turned off) :

http://img48.imageshack.us/my.php?image=dsc02306xv0.jpg

First subwoofer on, second subwoofer off equalized response :

http://img440.imageshack.us/my.php?image=dsc02305wl8.jpg

So my questions are as follows. Should I calibrate both subwoofers to the same SPL level individually and then lower the net result using the subwoofer level and then EQ the end result ? Or must I just set the gain levels the same and then lower the subwoofer level and then EQ the end result ?

The reason why I say this is because the gain levels differ slightly on each subwoofer to reach the same SPL level at the seats. Mark Seaton told me that I should set the gain levels identically on both subwoofers even if each subwoofers output is not the same at the seats. According to him it's the net SPL that matters.

I recently had a bit of debate about this. I just want to know what is the best way to EQ both subwoofers for low distortion and highest output. My argument is that I gain more output due to coupling when the SPL levels are set up the same per sub at the seats. I don't gain as much "free" output when I don't do this.

I'm not the most experienced when using the SMS-1. Any thoughts would be appreciated.

Regards,


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## jdeanmc (Aug 26, 2008)

GregBe said:


> You may want to take that even further, and raise the master volume even further when calibrating and get it to 0dB. That way you have a easy gauge how far away you are from reference level when you watch (reference level being 0 dB in this case). That would bring the channel level of your speakers down to 0 or negative. In the grand scheme of things it really shouldn't matter, as long as it is calibrated, but some say having your channel levels at 0 or lower helps with distortion. I personally like having my reference level at 0 dB, so when if I am watching at -10dB, I know I am 10 dB below reference.


I will try this.i still also want to rerun ypao to set eq levels now that ive changed the speaker levels,i will change reference to 0 first.
Thanks
Dean


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## salvasol (Oct 31, 2006)

jdeanmc said:


> I will try this.i still also want to rerun ypao to set eq levels now that ive changed the speaker levels,i will change reference to 0 first...


You don't have to change anything ....YPAO will do it for you.

This is What I will do if I were you:

1. Run YPAO to calibrate.

2. Manually adjust anything that is set incorrectly (I also use YPAO, and most of the time can be distance, speaker size, crossover).

3. Use calibrating disc (DVE, THX optimizer, etc) and using the SPL meter change the speaker levels (if need it) to get 75.0db

P.S.: YPAO will set the master volume to 0.0db when calibrating (depending on your set up, the final results can be different an maybe your reference will be below zero :yes: ...after I run YPAO on my system, when I used the SPL to check the set up I was reading 80+db with MV @ 0.0db ... so I lowered until I got 75.0db (that was @ -7.5db) ... then I checked and adjusted all speaker. This means that YPAO calibrated @ 0.0db but the reference volume was set @ -7.5 to get reference levels) :yes:


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## Ricci (May 23, 2007)

Vaughan100 said:


> Guys,
> 
> I'm going to need some help from those with experience with the SMS-1.  So I'm not done yet. I'm only getting started.
> 
> ...


I agree with Mark. 

1. Calibrate one sub to 75db or so (whatever doesn't really matter yet so long as you match this with the 2nd sw). 

2.Then move the other sub to the exact same spot as the first sub was measured and set it for an identical level. At this point you should leave the SW gains alone and start messing with placement of the 2 subs if you can. 

3.Find the spot with the flattest FR or most deep bass reinforcement (take your pick) for the 1st sw. 

4.Then identify what the weaknesses in that response are and play around with positioning of the 2nd sw and try to find a spot that ends up with the best combined response. 

5.Then EQ both sw's together to further shape things up. 

6.Finally recalibrate to whatever overall SW level you wish using the reciever/ processor sw level control.

This would only work for identical subs.


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## Doctor X (Apr 3, 2007)

Ricci said:


> 1. Calibrate one sub to 75db or so (whatever doesn't really matter yet so long as you match this with the 2nd sw).


I have done this. Except the gain levels on both subwoofers are slightly different. The second subwoofer requires a gain level set 10% higher than the first to reach the same SPL at the seats. According to Mark, I should set the gain on both subwoofers the same.

But if I do this then each individual subwoofer will not be putting out the same SPL at the seats anymore. 



> 2.Then move the other sub to the exact same spot as the first sub was measured and set it for an identical level. At this point you should leave the SW gains alone and start messing with placement of the 2 subs if you can.


My subwoofers are placed about 4 m apart. Unfortunately I can't position my subwoofers anywhere else. The first subwoofer is placed in a corner while the second is close to a wall but out from the corner (half a meter or so).



> 5.Then EQ both sw's together to further shape things up.


Alright. Thanks.

Regards,


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## Ricci (May 23, 2007)

That sounds fine but did you measure the level of the 2nd subwoofer placed *at the same position* as the first SW was when it was measured? This is key. If the gains on the plate amps end up slightly different this is ok as there will be some variation between units.


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## Doctor X (Apr 3, 2007)

> That sounds fine but did you measure the level of the 2nd subwoofer placed at the same position as the first SW was when it was measured?


No. I have two subwoofers placed 4 m apart. I took the first subwoofer measured in the corner and measured to a given level. The second subwoofer I put on and calibrated to the very same level and didn't change it's location. Both on together yields far greater output at the seats and then I just lower the subwoofer level to reach my desired SPL.

But no, I didn't physically drag the second subwoofer to the first subwoofer location if that is what you are saying. In any case, both subwoofers are loading the two spaces differently.

Regards,


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## salvasol (Oct 31, 2006)

Ricci said:


> ...did you measure the level of the 2nd subwoofer placed *at the same position* as the first SW was when it was measured? ...


I don't see any benefit on measuring/calibrating both sub in the same position :huh: ...maybe I'm missing something, but, if I will use the second sub in the back of the room and not at the same distance of the front sub ... Why I have to calibrate it using the front position???? ...I think is better to calibrate it at the position where it will be used and then adjust the level on the AVR when both are playing ...:yes:


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## Ricci (May 23, 2007)

It's very simple. This is the only way to ensure that the subwoofers are truly level/gain/SPL matched(whatever you want to call it. It's all the same thing. Gain does not mean that little knob on the back of a SW plate amp necessarily.) . This will insure that both subs are working equally hard and will run out of gas or be overdriven at the same time *You do not want to level match them from different positions. * Of course one sub may be contributing the majority of the output at the listening position when it's all said and done, but that *does not matter*. It's about using the subs to the best of *BOTH *of their abilities and even power distribution between them. Completely regardless of where your SW's will be placed finally in the room, or car, or outside or wherever they finally end up.

During initial set-up pull both subs out into the middle of the room and put your mic or SPL meter close to the driver pointed directly at the cone. Set the level of the first one to whatever you want. Move it out of the way and repeat with the 2nd sw . Now they are level/gain matched and you then proceed with your calibrations from there. Mess with positioning, EQ, overall SW level from your preamp or reciever, whatever. Just apply it to both subs equally.


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## Doctor X (Apr 3, 2007)

Ricci said:


> This will insure that both subs are working equally hard and will run out of gas or be overdriven at the same time You do not want to level match them from different positions. Of course one sub may be contributing the majority of the output at the listening position when it's all said and done, but that does not matter. It's about using the subs to the best of BOTH of their abilities and even power distribution between them.


Yes but then I might as well just set the gain levels exactly the same on each subwoofer regardless of whether the in room output for each contributing subwoofer is the same. There isn't any point in dragging the second subwoofer to the first sub's location if all I really need to do is set the gain levels the same. That is precisely what Mark Seaton has recommended, setting the gain levels the same. However his approach will not allow me to achieve full coupling between both subwoofers within the room and at the seats.



> Completely regardless of where your SW's will be placed finally in the room, or car, or outside or wherever they finally end up.


The reason why I wanted to calibrate both subwoofers to equal levels is because of mutual coupling. In order for you to strengthen this coupling process both subwoofers must be operating in phase *and* in level. I spoke about this at length on AVS. Mark Seaton apparently agreed with my reasoning but nevertheless recommended his set up procedure which I don't agree with (but respect).

Regards,


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## Ricci (May 23, 2007)

You have to understand that Mark does not mean the little volume control knob on the plate amp on the SW. 

You are actually not getting the mutual coupling the way that you seem to insist on doing things, because one SW is working much harder than the other. You are also robbing yourself of headroom.


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## Doctor X (Apr 3, 2007)

Ricci said:


> You have to understand that Mark does not mean the little volume control knob on the plate amp on the SW.


I think that is exactly what Mark is referring to. Equal gain settings. Unless he mean't something entirely different. 



> You are actually not getting the mutual coupling the way that you seem to insist on doing things, because one SW is working much harder than the other. You are also robbing yourself of headroom.


I'm actually not.  I'm actually gaining output at the seats due to the stronger coupling between both subwoofers when their levels are matched at the seats. The reasons for this are simple. The gain level is 10% off but this is offset by a much larger net increase in SPL at the seats. I then reduce the level in unity and my distortion levels are even lower.

Regards,


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## salvasol (Oct 31, 2006)

Ricci said:


> . This will insure that both subs are working equally hard and will run out of gas or be overdriven at the same time *You do not want to level match them from different positions. * Of course one sub may be contributing the majority of the output at the listening position when it's all said and done, but that *does not matter*.


Now it makes sense ...:yes:



> During initial set-up pull both subs out into the middle of the room and put your mic or SPL meter close to the driver pointed directly at the cone. Set the level of the first one to whatever you want. Move it out of the way and repeat with the 2nd sw . Now they are level/gain matched and you then proceed with your calibrations from there. Mess with positioning, EQ, overall SW level from your preamp or reciever, whatever. Just apply it to both subs equally.


What about placing one on top of the other and set one at a time??? ...I was thinking to place them in the same corner but I don't think is a good idea, specially if one will be used in another place (room gain will affect, Right???)


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