Level matching for blind tests - AVS Forum
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post #1 of 4 Old 10-03-2013, 10:38 AM - Thread Starter
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I've been lurking in this forum for quite a while and have read time and again that, when comparing audio equipment by ear, the equipment has to be level matched. Now I ask: how is the level matching done? By measuring voltage on the speaker leads?

Sorry for the poor english!
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post #2 of 4 Old 10-03-2013, 11:13 AM
 
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Yes. http://www.avsforum.com/t/1099689/how-to-level-match-components/30#post_15395066
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post #3 of 4 Old 10-03-2013, 11:47 AM
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I have level-matched a variety of ways in the past. Voltage matching works well for line-level components and power amps, less so for speakers which may vary by more than that in a pair due to their own errors or room interactions (I would check voltage at the terminals and with a decent mic). For components, I typically measured at 1 kHz using a precision RMS meter, then checked test tones at 20/50/100 Hz and 1/2/5/10/20 kHz. More or less. The last few years I was a tech we had equipment that would do wideband sweeps so I just did that instead. Most SS equipment is very flat 20 - 20 kHz so a 20 Hz/1 kHz/20 kHz check will usually do it. Tube components might show more variation depending upon loading.

For any testing we always level-matched to 0.1 dB or less at 1 kHz, and generally that held across the frequency band for all line-level components. Power amps, speakers, ack, usually matched at 1 kHz and prayed. smile.gif Sometimes we'd match at other frequencies due to a bump in speaker, room, or speaker/room response.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #4 of 4 Old 10-03-2013, 03:51 PM
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Quote:
Originally Posted by cegadede View Post

I've been lurking in this forum for quite a while and have read time and again that, when comparing audio equipment by ear, the equipment has to be level matched. Now I ask: how is the level matching done? By measuring voltage on the speaker leads?
!

Yes. The important thing to remember is that you want to match the voltages within about 1% which is about the same as 0.1 dB.

Its all about matching the two sources, not looking for flat frequency response. So, you can use a voltmeter that is not calibrated in dB and that does not itself have flat frequency response. A cheap 4 digit DVM that can be bought in a hardware store or home improvement store can do the job.
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