Wierd results when measuring soundcard response, need new S/Card??

**terry j** · **10-13-06, 08:43 PM**

thanks bruce, in actual fact using it up to 2k is more than adequate right now, I do hav a beh. mic, running into a DEQ 2496, so I'm hoping one day to be able to route that signal into the soundcard.

iS THERE A POST YOU COULD POINT ME TO (god I hate that, sorry, ) where it covers the points on what you've suggested. That would save me a three hour round trip to pick up the other soundcard now, get it next friday instead. Hoipe you're online still, gotta make a decision soon about whether to head off or not

lol
terry

**brucek** · **10-13-06, 09:04 PM**

When you save the soundcard.cal file (as explained in the REW HELP FILES) under Calibrating the soundcard, it will create a text file of the corrections for your card. I suspect the values up to about 2Khz are OK. I simply meant to edit it with Windows Notepad to remove the garbage above 2KHz or from where the garbage starts..

Attached is a small portion of my soundcard file. Look at it and see what I mean by it being text. Right button and Save target into your computer and then open it with Notepad. You'll see the correction values from 10Hz to about 1000Hz. The real file goes from 10Hz to 20KHz. If I had garbage from above 2Khz, I could simply remove the values above 2Khz if I wanted. This would make a usable cal file for you to use for low frequency work - your card only goes nuts above ~2KHz.

Make sense?

SoundCardCal.cal

brucek

**terry j** · **10-13-06, 09:21 PM**

yeah will try, thanks for answering quickly, didn't catch it straight away as I was mucking about with the google me feature. WOW, what a marvellous bit of program, zeroed in right to my property, could see the boundary lines and all, could even place the marker quite accurately within the property, amazing!!!

thanks, will get onto it now, then I will be able to answer your question whether it makes sense!

lots of love

terry

of course it didn't work, clicked on my google me and came up with a blank page. anyway will sort that another time

**terry j** · **10-14-06, 03:00 AM**

updates

first, thanks to 'the younger generation' got the google me going, still mightily impressed with it!

Also, am mightily impressed with REW, esp as it has been freely given to us all ( hope you're feeling validated John ((hope I got the right guy!)).

Thanks bruce, I've got some sort of soundcard cal filed away. Carried on after that, was very, very, very dissappointed to be still getting garbage results, totally unreadable results.

Pressed a few buttons (basically pounded the keyboard blindly in total frustration) and now it seems to be giving useable and useful results!!!

test plot.jpg

don't worry about any of it making sense, just pressing this button and that, reading help files etc.

thank you all so very much, will still get the other soundcard but that can wait.

Looks like it will be a breeze to get something happening next time someone logs on with the same graph eh!

will keep playing, reading the help files on the forum, will share my successes with you too

have a good one

terry

**brucek** · **10-14-06, 08:57 AM**

OK, a few points.

I hope you have loaded the meter calibration file that matches the Radio Shack Meter you are using found here (i.e. newrsanalog.cal). One of the three meter cal files has to be loaded into your computer. Simply store the file in the REW directory and pull down Meter in the REW program and load the meter cal file and select where you stored it.

It doesn't look like you loaded any Soundcardcal.cal file given the ruler flat response showing for that. Were you not able to create and edit that file? Could you post/attach the first 1000Hz of the file for me to see.

You have the CENTER Tab selected to test in REW. Was that your intent? If you want to test your subwoofer (I presume you do), then select the SUB tab in REW.

Once REW is hooked up and ready to go, there is an order that should be followed to get REW setup properly.
Roughly it's this:

Hook up cables - start REW - ensure meter cal and soundcard cal loaded. - select SUB tab - set cutoff frequency (i.e. 80hz)

1. Set Measurement Level.
2. Set Input Volume.
3.Calibrate SPL reading.
4. (if not previously done with a soundcardcal file in place) Calibrate the Soundcard here.
5. Set Target Level
6. Automatic Measurement.
7. Find Peaks
8. Assign Filters
9. Optimize Gain & Q.

Does this help?

brucek

**terry j** · **10-14-06, 11:11 AM**

thanks bruce

you were right, well spotted. Now loaded the correction file, can see how the line changed.

I just successfully ( I think ) edited the soundcard file, deleted everything above 2000 hz. which I must confess I hadn't done at the time of last post. Maybe it wasn't a successful operation after all, I just tried attaching it for you but got an invalid file error message. I see yours was a cal file, mine only seemed to be a text file(?)

Centre was selected simply because what I'm listening to that is connected to the computer right now are bookshelves, only really go down to about 50 hz. Will use these till I get the hang of the program.

your little summary does help, on the first few? readings of the help files that intrinsic simplicity of the procedure gets lost under the verbiage of the explanation.

right now, the only unclear point in your summary for me is the set target step, didn't quite get it last time. Won't worry too much yet, will go thru it again with the correct files loaded etc.

Have not got any processor yet, nor even a home theatre amp, just using two stereo amps in a bi-amp config on the speakers. Will do a bit more reading on the forum re the pros and cons of the different choices. Yes you're right, basically want to tame the bass, so will at the very least have to wait to lug everything into the other room in order to be able to hook it up to my full range.

Just thought of something that you may be able to answer, and depending on that answer help decide which unit to go for. I will probably use my existing 3 ways and put a sub into the system. The three ways are currently tri-amped using the beh. dcx2496, but will sometime reasonably soon upgrade to using the deqx unit to tri amp. My problem is how to get a sub into the system, mainly the hookup. Can any of the units usually considered plug into such a system easily? As my limited understanding of the matter stands, they would normally plug into some sort of low frequency output from a receiver, that is all the xover and processing is done. In a purely stereo sit ( no amps with lfe out or whatever) is it getting complicated? I don't expect you to solve this problem for me, but your knowledge of the products may give an exact answer. Hope that all made some sort of sense!

Will reply now, but may leave the question on my invalid file, and whether that means I have successfully edited my soundcard file, till tomorrow as its early in the morning. By the time I get back to it you amy be able to assure me I've got a functioning file, or how to save it correctly.( just had another quick look, the file extension is cal so not really sure why I couldn't upload it to you). I got rid of thousands of values in notepad, but when I load the cal file in soundcard it tells me I've loaded 22050!, so obviously not completely successful yet.

Will sleep on it, maybe I can think a bit more clearly later

lots of love
terry

**terry j** · **10-14-06, 11:29 AM**

had another quick look, think where I'm getting stuck is after notepad. I get rid of all the data above 2000, and it gets saved in a folder I made. When IO look it up again I can see a txt extension on it. When in notepad and use the save as function, there is no optio I can select that gives me a cal extension./

So, I've got the file edited to only use the data below 2000, but I guess it's just sitting there unusable at the moment.

**terry j** · **10-14-06, 11:33 AM**

hey!!just did it I think, loaded a s/card calibration file (even had a txt extension) and the dialog box told me I only loaded 2000 points!!

**brucek** · **10-14-06, 11:51 AM**

Quote:

I see yours was a cal file, mine only seemed to be a text file(?)

The extension doesn't matter really. I just used .cal to remind myself and to be consistent with the help files. A .txt is easier I suppose since you can simply double click and Notepad will be the editer. With a .cal extension you have to double click, then select Notepad as the editor. Either way, look at my attached soundcard file above and see what it looks like up to 1000Hz. Yours will be the same except a bit longer up to 2000Hz. You should be able to attach it unless it's larger than the site allows, but it tells you if it's too big, so there should be no problem attaching it.

Quote:

the only unclear point in your summary for me is the set target step, didn't quite get it last time

The target is basically used to determine the filters that are created when you push Find Peaks / Assign filters. It tells REW where the response is above or below the target line. You can manually set it also.

Quote:

In a purely stereo sit ( no amps with lfe out or whatever) is it getting complicated?

No, it's fairly easy to do what you want. I don't have enough information on your sub or your source (pre-amp) that you feed the power amps with, so it's hard to be specific.
But, generally at the source stereo output (which is a low impedance, line level signal) you would split the signal with a "Y-splitter". There will be no loss, since the devices that the outputs of the Y-splitters will feed are high input impedance.

One free side of the splitters (Left) and (Right) channel will feed a BFD DSP1124's left and right channel. The left and right channel output of the BFD then feed a sub with left and right input. The sub will be used to control bass management, since it is being fed a full range signal. Since I suspect your mains are also full-range, then it would be wise to choose a low crossover at the sub around 40Hz to 60Hz to simply compliment the lower end where the mains naturally roll off.

Here's the rub. If the sub doesn't enjoy a left and right channel input and only has a single LFE input, then you will be required to add a combiner to create a mono channel of the stereo signal to feed the sub, like this. It would connect at the output of the BFD before the sub. I haven't tried this specific device, but it looks OK....

Make sense?

brucek

**terry j** · **10-14-06, 11:59 AM**

yes, just found it under the view option, in calibration files details, meter/mic is the newrsanalog.cal,,,,soundcard calibration file is a file with a txt extension, the one I made earlier

so, progress made thankyou, sleep well !!

**terry j** · **10-14-06, 12:01 PM**

sorry posted without knowing you'd already replied! will digest it tomorrow, pretty knackered now, thanks heaps

**terry j** · **10-15-06, 02:39 AM**

righto. First the good news. Load the program and I'm informed that the calibration file for the mic is loaded, then informed that the figures up to 2000 hz have been loaded.

then as per the standard steps set

1. Set Measurement Level.
2. Set Input Volume.
3.Calibrate SPL reading.
4. (if not previously done with a soundcardcal file in place) Calibrate the Soundcard here.

As they have been loaded we are fine up to here. First question. The help files all talk about using the AV processor, and selecting which channel to measure. ( By the way, what is TMREQ ?). I have my out put connected to the input on the preamp, can hear the sweep tones etc etc, but it is always in both channels. Do I manually disconnect each channel in turn to make the measurements?, ie are they not controlled from the software?

Ok, taking each channel in turn, by connecting and disconnecting as required, and with a seperately set target level for each (?) I can take automatic measurements.

For the sake of the exercise, I'm using my bookshelves as 'mains' ie the left and right, and selecting bass limited at 50 hz. The readings only go up to 200 hz.

However, something is obviously very wrong. The preamp is the deqx unit, and just by way of explanation has eq filters. As different filters are selected obviously the sound changes, and so should the measured response. Don't worry about the actual eq settings, they are just at random but opposite ends of the spectrum

bypass.jpg

right@bypass.jpg

profile2.jpg

right@profile2.jpg

As you can see major changes in the eq settings (can hear the difference with pink noise for example) but hardly any qualitative changes in the 'measured' response. Is at a lower level, but that would be expected from the relative eq settings. Funny thing is, if the levels are diferent then the mic is picking up something different, yet the graphs as such don't change.

Anyway, let's start another round!!

lots of love

terry

**JohnM** · **10-15-06, 05:35 AM**

Look at the numbers on the left of the REW graphs, there has been a huge change in the results. Bear in mind that in the REW plot you are loking at a narrow range, 20 to 200Hz, whilst your DEQX filter is very broad, spanning about 20 to 800Hz, so the main effect of that broad filter on the narrow REW measurement is to shift the overall level within the measured range. Try measuring the effect with a much narrower filter and/or measure over a wider range with REW and you'll start to see more correspondence between the plots.

TMREQ = Tag McLaren Room EQualisation, an EQ feature that was part of the TAG McLaren Audio AV32R and AV192R AV processors.

**terry j** · **10-15-06, 06:06 AM**

thanks John, just thought you'd like to see this, as a direct result of your observations. Kept exactly the same settings on the deqx as before

test 1.jpg

test 2.jpg

as you can see, there was a bit of difference in the end!

will keep mucking about now, thanks for that. Will manually pull out each channel for measuring, thanks.

realised I've got the wrong limits on the vertical graph, but what is important is that you spotted the problem

lots of love

terry

**brucek** · **10-15-06, 08:03 AM**

Quote:

Do I manually disconnect each channel in turn to make the measurements?,

You can either just reconnect the REW signal to the channel of interest, or disconnect the speaker of the other channel(s).

Quote:

ie are they not controlled from the software?

Hehehe, and since REW mono signal is output on a single analog channel from your computer, how do you propose it control your different receiver channels?

Quote:

Ok, taking each channel in turn, by connecting and disconnecting as required, and with a seperately set target level for each (?)

The target would likely be about the same for both mains.

Quote:

realised I've got the wrong limits on the vertical graph, but what is important is that you spotted the problem

Yeah, this is something you have to watch for. REW will change the vertical scale to accomodate each measurement. To keep consistancy you have to return to a standard scale each time (we use 45dB to 105dB usually). You can enter the scale limits for easy retrieval into the Set Graph Axis Extends button on the bottom right of the REW graph. Then when you click it you can easily press one button to set your favourite axis limits after each measurement if something has changed.

Your speakers are dropping off fairly rapidly below 60Hz.

brucek

**terry j** · **10-15-06, 08:13 AM**

hi bruce,
just found the diagram you provided in one of Sonnies sticky posts, shows the right out splitting into two for the l&r aux in.

"""Hehehe, and since REW mono signal is output on a single analog channel from your computer, how do you propose it control your different receiver channels? """"

What, by now you haven't realized I'm a computer illiterate!?!

Yeah, the speakers have got a 60 db/oct high pass filter on them at 50 hz. You got that one right.

Will keep fiddling for a little while longer, but I guess I should put it to use with one of the units. Gotta get a sub too! Will hunt around the posts and see which model is the best to get.

look after yourself, have a breather while you can cause I'm sure I'll be back ha ha ha ha, with more dumb questions, (evil) ha ha ha ha!

thanks guys

terry

**terry j** · **10-26-06, 09:53 PM**

hi everybody

finally borrowed my mates external soundcard, creative soundblaster. The results are a lot better, tho nowhere as flat as the external souncard example in the help files, only as good as the internal example in the help files ( boy that sentence sounded awkward!, hope you understood).

I have been mucking about equalizing the bass, but not using the bfd, but will start a new thread because it may be of interest to others ( yeeeah, will finally be able to help and contribute!), and will make a few points that I've learnt on my way.

I won't bother posting pics of the soundcard response, but I am up and running and very happy indeed so will end this thread with a final thankyou to you all.

lots of love

terry

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