# Two days, 12+ Hours, How do I interpret this...?



## jrittz (Jan 8, 2011)

I've spent a TON of time researching and sub crawling, and repositioning subs, and calibrating sound levels, and and and...

So I've been able to calibrate it at 75db and did two runs (Among the hundreds previously.)

My last two runs and sub positions seem to give me the closes resemblance to a flat response but... it's not close to many I've seen posted.

How do I move forward and interpret what's going on with these two curves?

#1 The blue is two subs calibrated at 75db's and I believe out of phase.
#2 The maroon is the same two subs, same two positions and, I believe, in phase. I believe the maroon is now on the right track but I do not know what it's telling me beyond it's not flat? It's probably my room which is my family room without any sort of treatments. I'm fairly new to HT and so at this point, I've VERY proud of myself for being able to actually get something in the realm of "normal". 

Front sub is a VTF-15H and rear sub is VTF2-MK3. The VTF2 is the phase I changed.

I have also attached a layout of my room. The 15H is in the top left, the old VTF2-MK3 position (position #1). The VTF2 is in the bottom left (Blue Square). My options are very limited as to where I can place subs.

Edit: Added one more screenshot which has my soundcard calibration and Mic/Meter calibration.

I had the 15H at the red square and the VTF2 in position #1 with far worse results. I have also tried 15H in position #1 and VTF2 in red square. Best results so far are 15H in pos. #1 and VTF2 in blue square.

So I'm not sure what's necessary here but here is what I have:

Laptop with external sound card which is the SoundBlaster X-Fi Pro (Best Buy 69.99) and installed the drivers/software that came with it.
Windows 7 Pro
REW v5 w/Java 6 Update 20
Radio Shack Digital Sound Meter

I have calibrated the sound card as well as I'm using the provided Radio Shack .cal.

My HT Stuff:
Denon AVR-3311CI
eD A6.t's for fronts
eD A6.mtm for center
eD A4.b's for my four rears
Hsu VTF2-MK3
Hsu VTF-15H
Samsung 61" Rear Projection LED DLP
Panasonic BDP

Please let me know if I've left out any necessary information. I'm pretty sleepy and I'm semi-rushing this post.

Thank you so much for any feedback any can give, I appreciate any and all help I can get.

Regards,
Jaime


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## JohnM (Apr 11, 2006)

That looks pretty good, would be interesting to see the response a bit further up the frequency range and to see how the sub blends with the mains. Could try adjusting the Q control and/or the port foam plugs on the VTF-15H to see how that affects the big bump below 20Hz.


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## jrittz (Jan 8, 2011)

Yeah, when I get home from work I will definately adjust the Q control and the port plugs. I think I changed the Q to .3 from .7 but changing too many things at once and being tired...now that I'm on the right track, I can definately take some more time to make subtle changes between runs to see the impact. At this point, it seems like fine tuning is where I'm at which is awesome news.

I will definately go further up the frequency range. How far is a good point? 250? or is that too high?

Common sense to me here is that I should Y the current input to the receiver to use both left and right channels and use both mains + both subs to see what the frequency does... Is that correct? Or my other option is to use both left and right outputs from the sound card and then I should just get a 25' L/R RCA for the inputs on the receiver... I think both signals from Left and Right channels of the sound card are the same signal if I remember reading correctly...so in which case, it shouldn't matter if I Y the output/input to/from the sound card/receiver because it's all the same signal...

Both subs are definately tuned, at this point, for extension and so I may have a bit too much on the low-end side of things. I could certainly look at making one more for output and the other for extension to see how that helps the <20 range.

I really appreciate the response, John, it definately helps my confidence when you say "looks pretty good" in the fact that I'm not way out in left field here.


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## JohnM (Apr 11, 2006)

Best to measure left+subs, right+subs and left+right+subs. Make sure the distances are set correctly in your processor for your measurement position. The test signal is on both left and right outputs, so you can either split one at the processor or take a stereo lead to the processor and connect left/right/both as required.


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## jrittz (Jan 8, 2011)

I just now did see from other posts that, in any order, L+SW's, R+SW's, and then L+R+SW's is the way to go...

John, thanks again for the quick response, I appreciate it.

One answer I have not been able to get answered (Of course, if this information is in the documentation, I'm still working on it as I am doing this step by step rather than reading everything through the first time as it is a lot to take in all at once.). After I have run REW and calibrated the sub's and sub's + FL/FR and gotten the desired output, do I then calibrate my HT system as I had in the past? Which is:
Sub 1 on, Sub 2 off - Run one measurement from position 1 and adjust the gain on the subwoofer to be within +/- 3db's within the AVR's speaker levels, once achieved, move to:
Sub 1 off, Sub 2 on - Run one measurement from position 1 and adjust the gain on that subwoofer to be within +/- 3db's within the AVR's speaker levels, once achieved, move to:
Sub 1 on, Sub 2 on - Run the full calibration with Audyssey MultEQ XT (8 Positions)

I'll doing the sweeps later and if any further questions come up, respond to the above post(s) later today...for now I suppose I can try to get some answers as to next steps once the fine tuning is done with REW.

Regards,
Jaime


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## JohnM (Apr 11, 2006)

I've not had to set levels for a pair of subs, but your method sounds sensible. To save time setting the levels it may be easiest to use the REW RTA to view the response so you can adjust gain and watch the effect. Tick the "Adjust RTA Levels" box in the RTA controls to get levels that you can relate to those a sweep measurement would produce. You can find info about the RTA here, although that post is for V4 and before the "Adjust RTA Levels" option was added.


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## STC (Mar 16, 2011)

Hi everyone,

This is my first attempt using REW and not sure if I have done it correctly. I used a SPL meter and also a small condenser mic used to setup my Onyko AV but found the waterfall plot didn't reflect what I hear in the room. The bass in my listening room is sufficient but the waterfall plot shows it is lacking. I suspect I didn't calibrate the sound card correctly or it could be my mistake when I calibrated the SPL using C-weighting. There is slight error in the reading around 50Hz which is due to the air cond hum like noise. 

Any help is greatly appreciated.

Thanx
ST


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## STC (Mar 16, 2011)

Anyone?


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## ddgtr (Nov 1, 2009)

Readjust the waterfall window to show up to 200Hz and 600ms and post back.


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## STC (Mar 16, 2011)

Hi Danny,

Here you go...


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## ddgtr (Nov 1, 2009)

Sorry STC, I forgot to mention it: also readjust the vertical scale to show 45 to 105db.

Thanks!


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## STC (Mar 16, 2011)

Danny, you mean 45dB (positive) right?


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## ddgtr (Nov 1, 2009)

Here is an example of how the window should be sized... Yes, 45 to 105 positive.


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## STC (Mar 16, 2011)

Hi Danny,
I have redo everything again. There are only a few tops visible at 45dB and above. See you in one or two hours time

ST


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## ddgtr (Nov 1, 2009)

yeah, you probably have to check everything, also I don't know about that Onkyo mic...


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## STC (Mar 16, 2011)

Hi Danny,
Ok remeasured again using Prokit SPL meter. See if this is ok, please.


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## ddgtr (Nov 1, 2009)

Yes, this is it!

Ok, as you probably know, this is for the low frequencies. If you want to look at the entire frequency range, both the speakers and sub (or both speakers, or one speaker at a time depending on what you want) you will also need to post the SPL graph - use the same settings except for obviously go to 20kHz. Use both smoothing (say 1/12 or 1/6) and no smoothing at all to look at different things. The unsmoothed graphs will reveal quite a bit about your room acoustics, for example the room is too "live" the graph will look pretty ragged and spiky. More on that when you post the spl graphs...

I'm sure the heavyweights will weigh in with more detailed and better explanations, but this is what I can see from looking at your graph. The waterfall will tell you the most about acoustics, they can show you room modes (high peaks with longer decay times like you have from 25 to 40Hz).

It doesn't look bad, you can definitely try playing with the sub placement a bit to see if you can get a better response, for example to avoid the steep drops and high peaks as much as you can. Remember that very steep drops or valleys are nulls, which cannot really be EQ'd. Once you do that, then try applying a bit of EQ to see how it looks. Listen and see how you like it, and make necessary adjustments.

The long decay times you have at 24 to 40Hz are fairly normal at that range, and not too easy to get rid of. In many instances, sub placement will take care of a good part of that, then EQ will also decrease those times, so if moving your sub around is an option, then the two combined will work pretty good.

Do you have any treatments in place? What is your room like, floors, walls, furniture, etc? 

Cheers!


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## STC (Mar 16, 2011)

Hi Danny,

You have helped me more than I could ever hoped for. Ok, I don't use a sub. They were the measurements of my Harbeth SHL5. My room is well treated but all them are DIY stuff. The 25 to 40Hz is the air condition noise. My speakers spec is only down to 40. Will try to post my room plan in a day or two.

Meanwhile, could you please look at the dip at 60 to 100Hz. No matter, what I do those dips are almost impossible to treat them. Speaker placements only shift the dips. Did try a subwoofer but the problem just jumps to another place in the frequncies range.

Ok, time to sleep. Will try to upload the room ASAP.

Thanks and best regards,
ST


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## ddgtr (Nov 1, 2009)

Hi ST,

The Harbeth's are very nice speakers, congratulations!

Do you have bass traps, and if yes, how many? 

Regarding the dip from 60 to 100Hz - I would look at EQ options (given the fact you've tried placement), like a broader bandwidth to cover that span, boost it a bit and see what happens. What other gear are you running, I assume it's a 2 channel configuration, correct? And if so, are you willing to apply mild EQ (as I know many 2 channel purists do not want any EQ)? Are you streaming your music via a computer or are you using a CD/TT player? 

I'll tell you what I'm doing: streaming regular and hi-rez files via foobar2000, out through USB to a USB to SPDIF converter (to get bit perfect), out to the dac, preamp, amp and out to the speakers.

For foobar2000 I found an excellent VST plugin, it's called ElectriQ, it's a parametric equalizer, extremely flexible and easy to use. I've been monitoring my results in RTA, and they match perfectly the projected filtered response.

In your case, if you use a CD player then you might need to look at an external parametric EQ, I'll dig up a thread here, there is a gentleman who did EQ all the way up in a really elegant way.

I've applied some broad filters myself and have been pleased with the results so far.

Of course, your ears are the ultimate judge: you may or may not hear an improvement, or like it for that matter.

Regards


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## STC (Mar 16, 2011)

Hi Danny,

My room size is about 368cm(W) x 442cm(L) x 287cm(H). It was measured to spec to fit the so called golden ratio room. Can't remember the exact decimal places. No windows. This is my dedicated listening room. (Pictures coming soon)

My equipments:-

Marantz SA11S2 SACD/CD player
Supratek Chardonnay PreAmp (tube)
Classe CA-25 Amplifier - been with me for more than 10 years.
Theta Gen III DAC - same as above
Harbeth SHL5
Cables - I don't really believe in them. but I use XLO, Belden, and Audioquest. never changed them for more than 10 years.
Voltage regulated for source (player/DAC and Preamp) through Cetronics and Watford Controls (yeah..bit over kill but they were meant to be used in lab and I got it free  . To be fair I don't perceive any difference but it protects my sensitive source from high voltage which sometimes touches 258V.

Room treatment- QRD and skyline diffusers all are DIY stuff. Roxul Rockwool - a lot of them in boxes and also embedded in the wall. (double wall. 4 inch brick with 4 in gap and another 4inch brickwall). The good thing is there is no boom even with a sub. The bad thing is I am stuck because they are permanent and had a tough time covering them with diffusers because the room sounded dead with too much of Roxul  )

I am thinking of setting up a media server but unfortunately I am not well versed in tech. I intend to use my Theta DAC but still waiting to find someone who should be an expert who can help me out.

I am actually looking at Lyngdorf RP-1 room correction but it is very expensive the alternative would be a Rel Subwoofer with its built-in room correction. Frankly, I don't even know why I want to do that because the sound is good as it is but you know about this hobby right?

Cheers
ST


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## ddgtr (Nov 1, 2009)

STC said:


> I am actually looking at Lyngdorf RP-1 room correction but it is very expensive the alternative would be a Rel Subwoofer with its built-in room correction. Frankly, I don't even know why I want to do that because the sound is good as it is but you know about this hobby right?
> 
> Cheers
> ST


It seems we have similar rooms, mine does not have any windows either!! I've got OC703 and 705 covering the bass traps and first and second reflection points, ceiling, front and back wall along with poly diffusers. I built everything too!

See, here is the thing though: your response does not look bad at all, and it seems that you know very well what to look for when you listen to music, I can tell you are very particular and like to take care even of the smaller details. You've already done your homework on almost all fronts. Try a bit of eq on that dip and see if you can hear a difference.

Rel is a great sub, I'm currently looking at either a Rel, Rythmic or Hsu. I heard nothing but great things about Rythmic and for the price it looks really good right about now...

Also, setting up a music server would not be hard. I'm no expert, but if you need help it shouldn't be that hard. Foobar is free, all you need is a usb out of you pc and either a digital coax to your dac or even better, a usb to spdif converter to make sure you get bit perfect sound out to your dac. 

Cheers


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