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Discussion Starter #1
With the HPTC as the heart of my HT system, it just seems logical to be able to use it analyze the audio performance of my speakers and subwoofer. I've found software RTA analysis tools like ETF 5 and SpectraPlus . It seems that either of these applications would be a great addition to a HT, provided that you had some method of equalizing the output of your audio source.


So, my questions are:

1. Is anyone using either of these tools, and if so, how?

2. Is there any software that allows full parametric equalization of the audio being routed to the soundcard? If so, does it degrade sound quality (e.g., bit-shaving)?

3. How does one hook a microphone up to a M-Audio 24/96 or Delta Dio 24/96 soundcard? If one cannot, is it possible to run two soundcards?


Thanks,

Ken
 

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I use SpectraPlus. I have to admit that I'm not any kind of guru in that area though, at all. But it seems nice enough and its easy to understand and use. I bought a nice quality mic with a quite flat response down nice and low, and it uses 'compensation files' that you can easily create to compensate for any small deviations from flat that the mic might have.


You just plug it into the mic input of the sound card. I'm sure that the quality of your sound card's ADCs will have a good bit to do with the performance you'll get. But for tuning an HT, which isn't really lab level work, it shouldn't probably be a big problem.
 

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Discussion Starter #3
Dean:


Thanks for the reply! What mic did you buy?


- Ken
 

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Word of caution with buying mics for RTA. Will it work yes. But one thing that you two failed to mention is that the microphones themselves NEED to be calibrated. Last time I checked on RTA for computers they where upwards of $1250 USD. ANd one mic is good but if you can get four it would be much better. Since then you can measure decay and reverb and all that other good stuff and take an average of all four reading for the freq resp. the high end computer RTA have a seperate daughter board that are themselves calibrated.


Just my 2¢
 

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I can't remember the actual model off the top of my head. I'll check when I get home. I think it was a calibrated mic, with a nice flat frequency response and low end handling. It was about $150, and I got a nice boom stand for it.
 

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You know one thing i forgot to mention is that the one that are pretty flat are usually very directional which for room adjustments is almost worthless. I will give you the info when I get home. I have there broshures of the RTA and mic at home.
 

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Mine is an AudioTechnica ATM10a cardioid omnidirectional condenser mic. The condenser part is important for this application, for reasons I can't remember. And of course the omnidirectional part is important for reasons just mentioned by Figgie, in that you want to collection sound from as all around as possible.
 

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now this is really interesting.


you guys are saying that with software and a mic alone you can get accurate rt analysis???


i have looked into many pc-rta's and as mentioned.. they are quite expensive.


so what gives here??


im very interested in giving this a try. so does anyone know if there is a software parametric eq avaliable?


now the question is.... can you output the signal from your ht processor into a sound card.... tweak it with a software parametric eq.. and run it back into the receiver????? now that would be a handy thing to have
 

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Quote:
now the question is.... can you output the signal from your ht processor into a sound card.... tweak it with a software parametric eq.. and run it back into the receiver????? now that would be a handy thing to have
Yes, this can be done. The main issue is latency that is introduced by the OS/sound card/sound card drivers in this process. It's not so much of an issue for pure audio, but will cause problems for home theater. Also, you need a sound card with high quality d/a and a/d converters, preferably outboard.


There is a very interesting piece of software for linux called BruteFIR:
http://www.ludd.luth.se/~torger/brutefir.html

It claims to be able to run 60000 tap FIR filters on 10 channels simultaneously in realtime on a standard PC.
 

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Quote:
you guys are saying that with software and a mic alone you can get accurate rt analysis???
Well, that depends on what accurate means. We are talking about room tuning here. For that, its good enough, because we aren't talking about lab quality circumstances. Basically you want to find the peaks and dips and watch while you adjust speakers and room treatments to see what happens.


Some folks will say that a 1/3 octave RT, no matter how good, isn't good enough because many peaks and dips will fall into the cracks. But probably most of the software based ones that we humans could afford fall into that category, right?
 

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ahh finally found it.. pcRTA by linear X. I used to have one at my disposal in the Air force but not anymore =/


here is the link

http://www.linearx.com/products/anal...A/pcRTA_01.htm


works great too.


If you go to page 6 it does what I was telling you about the reverb and decay time. I also used this RTA alot for IASCA competitions. Now only if they can make that external box ... then you can connect a laptop to it :D
 
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