software

[Dave Jones]

Please help with a dumb newbie question.

I wonder if there's some way I can get a relative frequency response chart using the equipment I got on hand --

Computer with MS Windows 2000 Pro
Condenser mic and preamp (came with Richter Scale Series III)
Audigy II Sound card

I've got the mic plugged into the sound card, and I can hear my voice when I speak into the mic. So far, so good. Now what?

I downloaded Speaker Workshop, but I haven't gotten anywhere with it. The only tutorial for it that I've found is for a procedure that requires an impendance jig.

So... Any advice?

[wintermute]

Hi Dave,

If you just want to do some quick and dirty measurements to get a feel for things without going overboard, then there is one setting that is critical to do.

go to options/preferences and click on acoustic. select one channel for your mic input (obviously the one its plugged into) and select none for the other. If you don't do this you will either get virtually flat freq response curves or something completely out of whack.

When you are feeling like being a bit more adventurous then I would strongly suggest making a jig, it will be absolutely necessary if you decide to do and T/S measurements. and from what I've read you get much better freq response measurements if you use one too (basically one channel is fed from the mic and the other is the actual signal sent through the amp.

heres a link to the 2nd generation walin jig (I made the 1st). http://www.gti.net/wallin/audio/jig2/jig2.html

The tutorial from his first jig http://www.gti.net/wallin/audio/audua/audua.html
is also worth reading.

Oh and a final note, if your sound card doesn't have an inbuilt amp (most don't these days) you'll need to hook your sound card up to your amp, to get enough level to drive your speakers but your probably allready sussed that one out

Regards,

Tony.
edit: PS nice sound card

[Dave Jones]

Originally posted by wintermute
Hi Dave,

If you just want to do some quick and dirty measurements to get a feel for things without going overboard, then there is one setting that is critical to do.

go to options/preferences and click on acoustic. select one channel for your mic input (obviously the one its plugged into)

I've got it plugged into the line-in with a mono-to-stereo plug. So I guess either left or right should do.

and select none for the other. If you don't do this you will either get virtually flat freq response curves or something completely out of whack.

I'm getting frequency response charts, but no two look alike. I wonder if the mic is not turned up loud enough or something.

[Dave Jones]

Yep. Every chart looks different from the last. Also, the charts look *really* rough when they are not smoothed. The high end is a mangle of whiskers +=30 dB. I think it must not be set up right.

[MarkMcK]

Hi Dave,

It sounds like you are getting somewhere. At least you have found out how to make the measure menu appear.

We really need more details.

Are you choosing "pulse response" from the measure menu?

If so, when you open the "pulse response" from the file tree and the "calculate" menu appears, are you choosing "FFT?"


If so, are you using the select range to window the response and have you selected "uniform (none)" on the windowing option?

Mark

[Dave Jones]

"Pulse response" is not an option. Two of the options are "frequency response" and "time response". I've been clicking on "frequency response". I hear a "pfffft" sound, and then there's data in a chart called "untitled.frequency".

[MarkMcK]

Dave,

Great. That provides important information.

This is what makes Speakerworkshop intimidating. It is hard to figure out the user interface and the nested menus.

Pull down the "resource" menu and choose "New" and "driver." Input a name. It could be any name. When you do this a new file will appear in the tree. Double click on the file to open it and check the "measure" menu again. You should now see the "pulse response" option (next to last in the pull down menu).

Mark

[Dave Jones]

MarkMcK, you have new mail. :-)

[wintermute]

Hi Dave,

probably a couple of other settings I should have mentioned too

increase your sample size to the maximum (under options prefferences measurements 256K) change your sampling rate to 96Khz too (if it isn't available you need to tick the check 96Khz sampling rate box on the general tab, close SW and reopen it).

Also it may be necessary to play with your audigy settings. I've got my mike plugged into the mic input and have only the microphone selected as input also your output is important. you should only have wave selected on the source, DO NOT select line in or you will get feedback.

You may have to experiment with "what you hear" and "Analog mix" You may also need to use the built in windows sound thingy to select your input.

I've attached a file showing the freq curve from my very ordinary aiwa computer speakers. The first one is with 96Khz sampling rate and 256K sample size, the second is with 96Khz and 4K sampling size, to give you an idea of the difference. Note niether curve is smoothed.

Sounds like you are on the right track.

Regards,

Tony.

edit: I think the wild fluctuations above 20K are due to mic limitations. The sound card is pretty flat out to at least 30Khz from memory. If yours are occuring lower, it could be your mike only goes to say 15K.

[wintermute]

Heres my audigy setup

edit: Note at this point I have done absolutely no calibration with the audigy card.