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How to Match Levels?

I want to do some testing of digital sources with my Stax Omega phones, but I have no idea how to properly match the levels to within the golden .1db goal. I have heard that a sound meter (a la Radioshack) won't cut it.. why not? If I place the phones properly and place the mic between the phones and play 1 KHZ tone or something, how close will I be getting to properly matched levels. After years of buying gear based on sound and opinions, I honestly want to test some things now, and am surprised at how little info is available...

Any help?

-Adam
akimball
sean
6,231 posts
 
Are you trying to match levels at the headphones or at the source feeding the amplification chain ? Sean
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bomarc
501 posts
 
I seem to recall that the specs for the Radio Shack SPL meters say they are accurate to 1 or 2 dB (even though they may read in finer gradations). That should make you think twice about using them for level matching. They simply aren't designed for that use. Wrong tool for the job.

Seems to me Sean's got the right approach: level-match with a voltmeter somewhere earlier in the chain. Gain will be the same for all sources from that point on, so you can safely assume that what you're actually hearing is matched.
akimball OP
10 posts
 
Well, I am ideally trying to match the levels on the source devices (cd players, dacs). But I have no way of attenuating their signals so they are putting out the same voltage. All I want to do is to be able to A/B source components at the same levels. However, the pin config for Stax phones is funky, and has some very high voltages coming through it..

So, if I simply want to A/B source components and get the volumes equal.. what do I do?
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