Low Level Detail: An experimental search and test.

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Here's a totally different approach that was recommended by someone on another forum - play music through a system, and record it.

Feed the recording back through the system, record that.

Repeat the process.

Easy enough to do with Audacity. I've a speaker under test here that was basically unlistenable after about eight iterations. You could still tell which track was being played, but it was on a par with the cheapest of compact laptop speakers.

By repeating the process over and over again, you magnify all the errors that the system is producing.

Interesting test, I thought, although it's difficult to quantify exactly how the signal is degrading. The results are immediately and obviously audible, though.

Chris
 
I'd sure think mic placement would really affect the results too, whether it's a little too near the woofer or the tweeter. A full-range or coaxial might work better for that, but even so, ideally the mic should be "at usual listening distance" away, likely six feet or so, and you'd need an anechoic chamber to do it without the room sound dominating.

You could do this on a quiet day with the mic and speaker outside on stands 12+ feet in the air, but what would the neighbors think?
 
The repeated loop is often used with electronics, but with speakers it's going to be tricky. Getting too much of the room being the main problem, as noted. Frequency response quirks would also be magnified.

Yeah, the degradation of the frequency response was an issue, but what was left over seemed to have some time domain issues, too.
Could've been the room, though.

Interesting idea for testing acoustic tweaks, but maybe not what we're after here.

Back to digging signals out of pink noise!

Chris
 
Looking at all those mics...

You need to see this: Comparison of different microphone positions for orchestra instruments
A huge project, but an incredible resource.

FWIW, it's also the source of a lot of frustration for me as someone interested in home HiFi - instruments can sound very different (yet they're all obviously the same instrument) according to mic position. So, what's correct?
In the end, I give up and just aim to reproduce whatever the studio engineers have done (ie, never mind if it sounds exactly like a particular instrument or not) in a way that sounds good to me.

Chris
 
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