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Old 24th December 2005, 10:19 PM   #1
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Default system testing

Hi,
I recently built a system based on T2020 chip and Fostex 3.5" full range drivers. The system can be found here with pictures and a full description:
http://forum.audiogon.com/cgi-bin/fr...8131&read&3&4&
I would like to test the systems perforamance somehow. I don't have a lot of money to spend (the zebra woood speaker enclosures killed me). Is there PC based software that cna test perforamance using a USB mic. Any suggestions and help would be greatly appreciated.
Thanks
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Old 24th December 2005, 10:42 PM   #2
BWRX is offline BWRX  United States
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By performance do you mean frequency response? If so, you can purchase a SPL meter from Radio Shack to measure the SPL at any distance from the speakers, find a free sine wave generator for your computer to generate test tones or buy a test tone cd, then you can measure, enter, and plot your results in an excel spreadsheet. You can make a simple stand out of scrap MDF to hold the SPL meter so your results are more precise. That method is cheap and works reasonably well but is time consuming if you want to have a lot of data points. Of course you can always just go by how it sounds to your ears that's even cheaper! Very nice job with the cabinet cosmetics.

Also, if you can find a free sweep generator you can do a slow sweep from 20Hz to 20kHz and watch the SPL meter to see approximately which frequencies give you the most variation in SPL. Then you can take more measurements around those frequencies and save some time in acquiring decent frequency response plots.

For a quick and dirty evaluation I like to just do a slow sweep with the SPL meter in my listening position and see the levels. You can change the position of the speakers as you see fit and do it again until you get results you're looking for (sometimes you don't quite see the results you'd like but it still sounds good and that's perfectly fine because the main idea is that you enjoy the music).
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Old 3rd January 2006, 03:34 PM   #3
nitrate is offline nitrate  United Kingdom
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Greetings,

I too want to make measurements of my homebuilt system but i want more amp specific measurements THD and all that. I have a sweep genarator and various other things, just don't know the correct way of going about things. Maybe sombody in the know should start a thread on true ( not theoretical ) real world audio related measurements. Anyone got a schematic of a simple SPL meter? They can't be that hard to build can they? It will be interesting to plot the freq response of my speakers as they are huge home built things but i must admit they sound Rubbish LOL. Maybe they lack a bass port of somthing Hmm.....

Have fun all,
Mad.P
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Old 3rd January 2006, 06:15 PM   #4
SSassen is offline SSassen  Netherlands
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Nitrate,

RightMark Audio Analyzer (RMAA) will do the trick, that's what I use and what many others use as well. Provided you got a sufficiently powerful PC with a high-quality soundcard you're all set. Here's a brief example of my recent endeavour with RMAA.

http://www.diyaudio.com/forums/showt...373#post804373

Best regards,

Sander Sassen
http://www.hardwareanalysis.com
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Old 4th January 2006, 12:59 PM   #5
nitrate is offline nitrate  United Kingdom
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Cheers Sander's,

Just what i neeeded. Now to see what i have really created LOL

Regards
Mad.P
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