# Low response level from REW to RS meter.



## Chrisbee (Apr 20, 2006)

Hi

When I connect my RS meter to my soundcard I can't get the signal level high enough to satisfy REW. I even tried connecting a cheap mike to check if something was broken in the RS meter. I obtained a 129dB reading in REW! I was then told my signal level was too low again! Woops! :blush: 

I have tried switching the RS meter up and down in scale without useful effect. I played around with the soundcard options: Wave, Soundblaster, default etc. I have Volume Control set at maximum and have played with the mute options on other channels. I must have tried all the other useful-looking buttons in REW. But now I seem to have run out of ideas. :scratch: 

After loads of stepped sinwave test runs and recording the results manually I'd really like to try the fast sweep option in REW now. 

I can hear the sweep on my sub but I can't record the results in REW.

Help?  

Thanks
Chris


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## Malice (May 1, 2006)

Are you using a line-in or a mic input for connection of the SPL meter? When I first tried the REW with a laptop I soon found similar problems with not having a line-in on the laptop. Dragging my trusty desktop into the equation "solved" the "level" problem by connecting to a line-in and not mic input. FWIW I found having the RS meter on 80db range the best for the readings into the REW.

HTH
Bob


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## JohnM (Apr 11, 2006)

What soundcard are you using and what input have you selected?

What level is shown on the REW SPL meter bar graph when playing a sub cal signal that shows 75dB on your RS meter with your RS meter on the 80dB range? What is the level when you stop the sub cal signal?


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## Chrisbee (Apr 20, 2006)

I'm using a Creative Audio PCI card in a fairly modern XP SP2 PC. Line in using turquoise jack socket.

The Calibrate function works okay. I'm using 80dB and the big box dB SPL figure changes slowly around that figure.

But when I try to set input level I'm getting no bars on the db fs meter.

RMS and Peak change constantly with RMS about 85dB and peak 10dB lower @ ~75dB. 

This still happens even when I have the RS meter switched off. So what is REW reading when there is no signal present?

Even when I pull the jack on the RS meter REW is still showing the changing dB figures as if nothing had happened. :scratch:

EDIT:I just ran a sweep after careful calibration and had the low signal warning showing -76dB.

But the graph area shows a nice flat curve above 85dB!

BTW: I had to set the level to -6dB to get my RS meter up to 75dB at the listening position on the Pink Noise level test.


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## brucek (Apr 11, 2006)

> RMS and Peak change constantly with RMS about 85dB and peak 10dB lower @ ~75dB.
> 
> This still happens even when I have the RS meter switched off. So what is REW reading when there is no signal present?
> 
> Even when I pull the jack on the RS meter REW is still showing the changing dB figures as if nothing had happened.


These statements seem to indicate a bad cable from the RS meter to the LINE-IN jack of your PC. 

Hopefully you are using a shielded mono cable that feeds into a stereo splitter plug, and are using the right channel only.

Does this 85dB signal that is present even when the RS meter is unplugged remain when you remove the cable from the LINE-IN jack of your PC?

If it does, do you have all the 'recording' properties of the volume control turned off except line-in and volume.

brucek


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## JohnM (Apr 11, 2006)

Creative mixers operate a little differently than others (not even consistent within their own range). You will probably find that you have to *unmute* the Line In in the source panel of the creative surround mixer, and the symbol above that input should have a '+' sign which when you click it will bring up a box to choose whether or not you want to monitor the input - make sure this is set to *NOT* monitor, and read the wording carefully because on some creative cards you check the box when you _don't_ want monitoring, on others you check the box when you _do_ want monitoring!

The reason you are getting SPL readings with no input is you have been through the SPL cal process, which has told the wizard that the signal level with no input corresponds to whatever cal level you used. Once you have got actual input signals to play with (as shown in the bar display) redo the SPL cal and all should be well.


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## Chrisbee (Apr 20, 2006)

Thanks for all the useful responses. 

I seem to be getting no input to my soundcard from any microphone I own regardless of which socket I try, which cable or which "mixer" settings I use. 

Output is fine.

I am being told the device is working properly. 
I'll just have to try again tomorrow.

Thanks again
Chris


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## Chrisbee (Apr 20, 2006)

Hi again

I have replaced my soundcard and can now show a nice curve. RS meter at the listening position 
@ 9 feet from my SVS 16-46PCi in my 30 feet long attic room open plan to lower floor via open stairwell.

This uses the RS meter correction values borrowed from the Shack. 

NO house curve applied. 

NO BFD. Computer driving the SVS cylinder amp direct via low level in.

NO speakers.

Crossover disabled.

Calibration at 82dB.


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## brucek (Apr 11, 2006)

> NO BFD


and you don't need one.....


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## Chrisbee (Apr 20, 2006)

brucek said:


> and you don't need one.....


Not bad is it?  

Any thoughts about the ideal vertical axis settings (in dB) for sharing these graphs? :scratch: 

I'm going to test my IB next. I think that will show the same trough around 12-14Hz too. :blush:

Life just isn't the same without one's full share of 12-14Hz! :laugh:


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## Malice (May 1, 2006)

Chrisbee said:


> NO BFD. Computer driving the SVS cylinder amp direct via low level in.










x 10


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## brucek (Apr 11, 2006)

> Any thoughts about the ideal vertical axis settings (in dB) for sharing these graphs


We always recommend 45dB to 105db vertical and 15Hz to 200Hz (but lower if your sub is worthy) horizontal , and 800 pics wide graph.

That way we all compare the same thing..

brucek


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## Chrisbee (Apr 20, 2006)

45-105dB? Do we really need that much room? :devil: 











This is my 4 x 15" AE IB15 Infinite Baffle vertical array. In-wall just left of left speaker centred on speaker baffle. Graph includes speakers. 4 BFD filters on sub. I've been too lazy to mess about with the filters once I set them manually using REW as an on-screen guide. It sounds great anyway. :T 

Note that same 12Hz room mode sucking away all my bass!! :rant:


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## Chrisbee (Apr 20, 2006)

This is the authorised graph size.  

With apologies to those vertically challenged by their curves.


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## Chrisbee (Apr 20, 2006)

brucek said:


> 15Hz to 200Hz (but lower if your sub is worthy).
> 
> brucek


When is REW going to offer 5Hz sweeps and graphs?


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## Chrisbee (Apr 20, 2006)

Malice said:


> x 10


Hi Malice

I always knew I had a good room.

Now if I could just cure that 12Hz dip...!


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## Sonnie (Apr 11, 2006)

*I am jealous!*


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## brucek (Apr 11, 2006)

Chris, can you explain the other line on your graph?

brucek


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## Malice (May 1, 2006)

Chrisbee said:


> Hi Malice
> 
> Now if I could just cure that 12Hz dip...!


:laugh: 

Opinions have been expressed that the dip is too narrow in Octave terms for you to notice any difference should you boost it.

You may not hear any difference, but any fillings in your teeth may!


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## Chrisbee (Apr 20, 2006)

brucek said:


> Chris, can you explain the other line on your graph?
> 
> brucek


I really can't remember now...  

Most likely my soundcard calibration curve (?)

Now don't go shooting down my response curves. :nono: 

I knew it was too good to be true! :blush:


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## brucek (Apr 11, 2006)

> Most likely my soundcard calibration curve (?)


I think the soundcard cal file is a dashed line?

Just wondered if it was your RSMeter calibration file? Hopefully not.

brucek


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## Sonnie (Apr 11, 2006)

If it is then that means his response at 10hz is gonna be like a atom bomb exploding.


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## brucek (Apr 11, 2006)

> If it is then that means his response at 10hz is gonna be like a atom bomb exploding


Yep.

What do you think it is Sonnie?

Sonnie, are your response lines red? Mine are purple?

brucek


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## Sonnie (Apr 11, 2006)

I don't know what else it could be besides a mic cal file. As you stated, the soundcard line is dotted or dashed.

My response line is purple too. But I think you get the different colors depending on what channel you measure on. For example, if he used "Left" speaker channel it may be red, "Right" may be green, "Sub" is purple, etc.

Chris, what channel did you measure on?


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## Chrisbee (Apr 20, 2006)

I believe the blue curve you mention is the simply the target response line for a full range run including the speakers. Clicking on that button makes that curve blink. This has no effect on the curve but merely offers a guideline for a suitable response curve. This would suggest I tested using "Left" rather than "Subwoofer". (I'm still finding my way around REW)

I loaded (the very long list) RS correction figures from the Shack. This is the solid black slightly bendy line falling to 65dB. It disappears when I click that button.

The rising dotted line is the REW soundcard calibration line. Again, this disappears when that particular button is clicked. 
This also has the irritating quality of looking almost exactly like an inverse of the RS correction curve. Is this possible if REW corrected for C-weighting automatically along the way? Or did something else?

Now I am filled with doubt and really haven't a clue whether my response curves are accurate or not! :blink:

I just looked at my graphs again and none of the above explains that black line! Does it?


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## Chrisbee (Apr 20, 2006)

Just for confirmation I cleared the date for correction from "Meter". I also cleared the soundcard data.

This black line is the reloaded (149 data list) for RS meter correction from the Shack. Now superimposed on the subwoofer blue guide line. I'd be grateful if somebody else could confirm their own correction list curve looks like this on their graph.

I'm just going to have to run my tests again without any soundcard calibration but still using the Shack's RS correction figures. I'll also be using the "Sub" graph rather than "Left".

I'll be back!


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## Sonnie (Apr 11, 2006)

That looks like maybe an inverted sound card file on that previous chart. I'd double check that.

I'd also take another measurement with the newrs.cal file loaded... I've got my doubts that it was the proper one loaded previously. If in fact your sound card cal file is correct then your response is gonna be astromomical in that lower region. That SVS is doing one **** of a job for ya! :yes:

When you save your graph, save it at 800 pixels wide so we don't get the scroll bar.


I don't think that's the right newrs.cal file. I think I may have the wrong one loaded... but it won't be that much different on the lower range. I'll check it out.


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## brucek (Apr 11, 2006)

Chris, I just looked at the calibration file that is presently posted on the site and it appears it has been corrrupted somehow. I'll let Sonnie know. I'm glad you brought this to our attention.

Anyway, here's a graph showing the basic SUB tab graph with the standard axis that we normally like to use from 15Hz to 200Hz horizontal and 45dB to 105dB vertical with an 800 pixel width.

Note, the correct RS meter cal file (that Sonnie will fix up).

Also note that most sound cards would be fairly flat (as shown here for my soundcard). A cheaper card would drop off a bit quicker at the lower frequencies.
I see that yours increases its response quite a bit at lower frequencies. There seems to be something wrong there. You should perhaps redo your soundcard cal check. The result is usually fairly flat as shown....













brucek


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## Chrisbee (Apr 20, 2006)

Thanks brucek

I cleared my original data and loaded your list as a .txt file.

The new curve is smoother but still follows the old curve quite closely.

I have run a couple of quick curves after recalibrating.

Now I am getting a perfect mirror image of the correction curve I just loaded!

I even get a curve with the RS meter unplugged! :yikes: 

Though not the same one!  

How does that work? 

I haven't yet discovered a way of keeping the previous curve for comparison. Is it possible in REW?


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## brucek (Apr 11, 2006)

> Now I am getting a perfect mirror image of the correction curve I just loaded!


Since the meter calibration file inversely modifiies the input response to REW, if you get a response curve that is a mirror image, it implies you are receiving a 'perfectly' flat input to REW. The implication is that you are receiving nothing to accomplish this. Are you sure the meter is still hooked up correctly and the REW SPL meter is calibrated showing activity etc...

brucek


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## Chrisbee (Apr 20, 2006)

Well, at least the mirror image is assymetric. If I can add in the soundcard calibration (later) this may well get me back to my original curve.

Despite the short nature of these tests I'm competing with my wife's favorite TV gardening programme and She is sitting in my listening chair! :blush: 

My attempts to train her to hold the RS meter in her teeth have (so far) proved completely futile. :devil: 

Later! 

EDIT: I can confirm calibration seems real and reflects what is happening with regards to numerical level, scale movement etc.


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## Sonnie (Apr 11, 2006)

Okay... whew! I have no idea what was happening but I've hopefully got it fixed now.


Ken, I deleted those numbers above since those are now back on the downloads page. If you will... double check that when you try to download them they are right. It worked for me but those ghost could be haunting us.


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## brucek (Apr 11, 2006)

> If you will... double check that when you try to download them they are right. It worked for me but those ghost could be haunting us


Yep, RS Meter calibration file ghosts have been destroyed. All is good in the shack.

Chris has some pesky woman problems to deal with now. It's a training and respect for the sub thing. He'll sort it out.

brucek


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## Chrisbee (Apr 20, 2006)

Okay. 
Here you can see the dotted black soundcard correction curve.
The solid black line is the RS meter correction curve from the Shack.

One of these graphs is a manual adjustment of frequency then "taking a reading". While the other is the result of an automatic sweep. I can't tell them apart but the first is the automatic sweep.

I do see a change in the numerical SPL readings when I calibrate and take a manual reading or a sweep.
I see a change in both REW SPL meters when I do any of the above..

The only conclusion is that the curves are accurate or simply reading an unchanging straightline situation as brucek suggests.

The sub here is my IB array. It's getting very late now so I'll re-run the SVS tests tomorrow.

I'd be grateful for any thoughts or procedures that would help rule out a false reading by REW.


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## brucek (Apr 11, 2006)

Chris, the mirror response of the calibration data is a known bug in REW that will be cleared by John in the next revision. I just remembered this.

See this thread

As John says:

_You need to repeat the soundcard cal with Line In selected as the input. To check the cal, first clear the mic calibration data as when you are connected in loopback there is no mic, so you end up with just the inverse of the mic cal if you haven't cleared it first. After the check, load the mic cal file again for your actual measurements. I'll update the help files to address this._

brucek


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## Chrisbee (Apr 20, 2006)

After three days I am still getting the same mirror image results. I have removed the soundcard and mike calibration data repeatedly without any change in my graph results.

I have gone back to using my Soundblaseter PCi card but still cannot get any results using Line-In. I couldn't get any response from Line-in using my replacement soundcard either in REW. I tried several mikes that I knew to be working in other applications as well as the RS SPL meter.

I am now using "Stereo Mix" as the input option which produces nice high input levels (full scale) on SPL meter calibration with the sub & speakers running. 
No real idea where this option came from but I reloaded the Soundblaster driver software from the supplied CD and then updated drivers online.



This is my soundcard response after several trials:

I am using a short phono to phono jumper lead from the input to the output of my Soundblaster PCi soundcard using phono/jack adaptors. Is this the correct procedure?

I am getting a warning of a very high -30dB noise level and overload on the soundcard response test. I note REW is showing -60dB as the test level.

Is this a typical soundcard response graph or am I just wasting my time here?


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## brucek (Apr 11, 2006)

> Is this a typical soundcard response graph or am I just wasting my time here?


No, that's not typical. Typical is basically a straight dotted flat response with a bit of dropping off below 20Hz and a dropping off above 10KHz.

That graph you show is either a connection problem in the output to input loop, or as REW indicates in its help file a feedback in the input output loop as a result of some soundcard feature for record monitoring (as john earlier suggested).

Your problems from the start seems to be that you're not getting signal into your soundcard. Are you using MONO cable that is connected to one of the stereo channels only as I earlier talked about?

brucek


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## Chrisbee (Apr 20, 2006)

Brucek

Of course I'm using mono cables.

I have spent yet another day running pointless sweeps, removing soundcards & removing software. Then refitting soundcards and re-loading software. Endlessly clearing and reloading correction data just added to the excitement. 

I have read and re-read all the REW help files from beginning to end. Other than that I am using a pre-power amp instead of an AV receiver or processor I can't see the problem. 

I can get a good signal using Line-in in the Windows microphone test (Recording under Sound, Speech and Audo devices) but I can't get anything using Line-in in REW.

I'm baffled. Line-in just won't work with REW even though my three devices work in the microphone test. (RS meter and two mikes)

When I set REW to use Wave instead of Line-in I get a monitoring effect. It looks as if the RS meter is working and sending signals to the soundcard input but it's really just REW monitoring its own output internally. 

Setting Input Level and Calibrating is just a visual sham. REW just accepts its internal soundcard monitoring. Any level I adjust to is all happily displayed on-screen it as if everything were working perfectly normally.

Logic suggests that I should have expected much the same curves as my manually recorded, stepped test tones. But all managed automatically within a few seconds instead of twenty (or forty) minutes per run then carefully typing and saving .txt files just to be able to see the results. 

But it's back to manual it seems. My patience and humour have finally run out.


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## brucek (Apr 11, 2006)

> My patience and humour have finally run out


No doubt, and I really sympathize with your situation here. 

I wish I could come up with a solution as to what is wrong. There's a culprit somewhere that I'm not seeing. I guess John M is away right now (Sonnie can comment on that), as I'm sure he could correct this trouble easily. Well, after all, he wrote the REW software. My expertise is electronics and the using of REW with a BFD, so I'm not much use I'm afraid. 

Normally, it all goes so easily and REW works great, but there's something amiss in your situation and hopefully we can find out what that is..... Believe me, manual method is no where near as accurate as REW. Let's wait until John can enter the picture on this one...

brucek


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## Sonnie (Apr 11, 2006)

Agree... we need John's help with this one. He's away out of town right now and don't have computer access. Hopefully he'll be available soon.


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## JohnM (Apr 11, 2006)

John here posting from South Africa over a somehwta unreliable and very slow connection (300 times slower than at home!). Will be back online properly next week, but a few tips for now.

If you use stereo mix, "what u hear" or similar as the input on REW you just get an internal loopback within the soundcard, so there is signal but its all local and no good to you. The ropey soundcard cal graph above is typical of running a test with some sort of internal loopback or monitoring active, causing severe comb filtering.

Need to use a line in to get things to work, if mic works OK as it seems to from your earlier posts, it depends on what your soundcard does for line inputs. On some SB cards you need to select "MICROPHONE" as input for either mic or line inputs, the card switches internally depending on what input it thinks is connected. Also on some SB you need to select "Analog Mix" and use a separate SB mixer menu to specify what is included in the analog mix. A final SB foible is that monitoring needs to be disabled, this is typically found on a separate menu accessed by clicking on the + by the symbol for the line in.

You can try skipping soundcard cal and meter cal and try using a mic connected to a mic input just to see if the basics can be made to work that way, if so it is down to getting the line in to work. Email me a copy of the debug file generated via the REW soundcard menu with REW set to your best guess of what should work and I'll have a look at that, but I may not be able to get to it until the weekend.

Regards,

John


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## Chrisbee (Apr 20, 2006)

Many thanks for your response John.

Relax, this can easily wait until you get back.

Installing an IB and the endless testing has just made me impatient to see the results on your handiwork. 

I've actually looked at the debug file a couple of times.
I'll have another look. I might even learn something useful. (Which will make a change)

Enjoy your trip. :T 

Best regards
Chrisbee


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## Chrisbee (Apr 20, 2006)

You might get a laugh from this: :blush: 

This is a dirt cheap microphone from a supermarket "computer" headset.

Microphone input because I still can't get Line-in to work on either PCI soundcard.

Still struggling for enough signal at the seating postion. The REW warning notice said something like -38dB peak.

I used the correction factors for the old analogue RS meter to flatter the response a little.

Feast your eyes on this:


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## Chrisbee (Apr 20, 2006)

Does anyone have any experience of REW with the Soundblaster Live! external USB soundcard?

I'm really getting nowhere with these cheap PCI cards despite downloading the latest drivers.


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## JohnM (Apr 11, 2006)

I bought one of the Live! 24-bit external USB cards just to check it out with REW, works fine and have also had reports from others using it successfully. Main oddity is that Line In needs to be unmuted in the mixer to work, and monitoring needs to be turned off.

Can't help feeling there is some simple explanation for the problems you are finding though, your mic measurement looks fine. Would be worth generating the soundcard debug file with everything set up using the mic, then making the Line In changes and generating the debug file again and email both to me. Also do you have the model numbers for the PCI cards you have tried?


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