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headphone amp performence measurement...... what do I need to do?

post #1 of 6
Thread Starter 

So I want to know the THD and noise floor and impose response of a DIY amp.... what equipment /program do I need to do such measurements ? Or is it better to just send the amp to place like innerfidelity and have it done there? any idea how much they charge for that kind of service?

post #2 of 6

InnerFidelity will do a bang up job.  I don't know how much it costs, but I would figure it's not cheap.

 

You'd need a sound card (a good one if you can) and some software and an interface to not fry your sound card if you loop directly in.  It'll give you a good idea of where you stand.

 

Some spectrum analyzer software (there's tons more out there)

 

http://www.qsl.net/dl4yhf/spectra1.html

http://www.trueaudio.com/rta_abt1.htm

http://www.supermegaultragroovy.com/products/FuzzMeasure/  (mac)

http://audio.rightmark.org/products/rmaa.shtml (basic software)

 

http://www.pmillett.com/ATEST.htm

post #3 of 6

The most straightforward way to obtain some gauge of how well an amp performs is to test it using RMAA (google it) in conjunction with a good quality soundcard, such as the ETI Juli@ or the Asus Xonar Essence ST or STX. Even a lesser soundcard than these can give useful results.

 

RMAA has come in for some criticism (google 'RMAA faults'), but used with discrimination, if you understand its shortcomings, it gives a quick insight into the performance of a variety of audio equipment.

 

w

post #4 of 6
Thread Starter 

Thanks for the info.

 

Audio interface boxes are not that expensive it seems, maybe I will try to do it myself. Since I am definitely not a computer guy, I am looking for a hardware/software package. I read somewhere the EMU0404 might be a "all in one" solution and it is not very spendy..... is there other good USB interface boxes that come with good-enough easy-to-use software?

 

And, if I want to add rudimentary headphone measurement capability, do I just add two microphones to the interface box?

post #5 of 6

The EMU0404 is another alternative with performance approaching that of the cards I mentioned, but the monetary saving is not that significant, it's just available for USB.

 

As far as software goes, RMAA is a free download unless you go for the pro version. The EMU soundcard (box) has no intrinsic advantage in terms of included software.

 

If you want to measure headphones (or IEMs), you need (as well as [calibrated] microphones) some kind of dummy head, or dummy ear canals for IEMs.

 

w

post #6 of 6
Quote:
Originally Posted by AudioCats View Post

Thanks for the info.

 

Audio interface boxes are not that expensive it seems, maybe I will try to do it myself. Since I am definitely not a computer guy, I am looking for a hardware/software package. I read somewhere the EMU0404 might be a "all in one" solution and it is not very spendy..... is there other good USB interface boxes that come with good-enough easy-to-use software?

 

And, if I want to add rudimentary headphone measurement capability, do I just add two microphones to the interface box?

All you need to look for is something that will accept input at the same time as giving output.  M-Audio has several offerings, or at least they used to.  I use the M-Audio Transit myself, but it's been discontinued and the drivers were never updated for Vista or Windows 7.  I have a little Netbook that still runs Windows XP and it runs fine just for the RMAA tests.

 

AMB used to use a Transit and then switched to an M-Audio USB, but as with the Transit, I'm not sure they sell it anymore.  Still, it shouldn't be that hard - if whatever you select can accept input at the same time as output, then you can run a loopback that will baseline all of your tests.

 

As for headphone measurement ... wow - I think you need to send a PM to Tyll on that one.


Edited by tomb - 8/18/13 at 6:27pm
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