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soundcard challenge, opinions welcome.

I've set up a test at www.kikeg.arrakis.es to test how good really are modern affordable soundcards, and digital in general. In this test, a musical clip has been looped several times through a soundcard (Audiophile 2496). There are 4 looped back clips and the non-looped back original, and the goal is to test if people's ears are really capable of detecting and/or rating the five clips.

Besides, a cheap RCA cable has been used for the loopback connection, so you can check by yourselves if cheap cables matter, as some people think.

I'd like the people at HA to do a first-round check of the materials at this page in order to possibily improve it, so any questions, comments or results would be much appreciated. Thanks.

KikeG

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...KikeG comes from spanish nickname...

soundcard challenge, opinions welcome.

Reply #1
In order to see if cheap cables really matter you'd need to provide samples using both a high-quality cable as well as the cheap cables.  If someone could pick out the difference then we could make a call.  I don't know of too many "high-quality" 1/8 mini to 1/8 mini cables though.  Monster might make one, but otherwise most high end cable manufacturers are making rca to rca audio interconnects.

G

soundcard challenge, opinions welcome.

Reply #2
Quote
Originally posted by gdougherty
I don't know of too many "high-quality" 1/8 mini to 1/8 mini cables though.


He's using the Audiophile for this test, which has RCA ins and outs... so that wouldn't be a problem.

soundcard challenge, opinions welcome.

Reply #3
Quote
Originally posted by gdougherty
In order to see if cheap cables really matter you'd need to provide samples using both a high-quality cable as well as the cheap cables.G


Well, as long as the original unprocessed file is also present in the test, I think this is not necessary. I mean, the unprocessed file is the best quality you can ever get, unless you think that a good cable "adds" quality to the original file.

soundcard challenge, opinions welcome.

Reply #4
Quote
Originally posted by KikeG


Well, as long as the original unprocessed file is also present in the test, I think this is not necessary. I mean, the unprocessed file is the best quality you can ever get, unless you think that a good cable "adds" quality to the original file.


(Note to moderators: feel free to move this thread to other section if you consider it appropiate)


If there is noticeable degredation though, both cheap and high-quality cables would need to be tested to see whether it's the a/d and d/a conversions that are the culprit or more the cheap cabling's fault.

G

soundcard challenge, opinions welcome.

Reply #5
Just read your website and the description of what you did.  You're adding additional modification through the compensation EQ that can be heard instead of just a flat re-recording process.  To re-eq seems to defeat the purpose of the test which I understand to be a test of the quality of the converters on your audiophile card.  If it does filter the audio during a record cycle then that is one way in which the card theoretically "misbehaves" like the upsampling to 48Khz that some cards do.

IMO you need to take this test back to the drawing board, make things a little more pure and focus on your real objectives.  I don't know that I can construct the perfect test for you, but my critical analysis immediately catches on these issues as obstacles to a truly meaningful result.

soundcard challenge, opinions welcome.

Reply #6
I know that I'm doing an additional processing of the signal by eq'ing it. The goal is, can you notice, just by listening, all the process that the signal has gone through, up to 4 times? Remember that you have too the absolutely unprocessed original signal.

The exact whole process is:

1 - conversion to 32 bit floating point of the original signal.
2 - level adjustment to optimize the playback/recording process.
3 - n times playback-record at 24 bits 44.1 KHz (up to 4 times).
4 - n times eq. to compensate for every playback-record process.
5 - level adjustment to match original signal.
6 - dither to go 16 bits.

The goal is not just testing the conversors at the card, is to know if cheap digital + cheap cables used properly are audible, and/or to what extent.

If there are easily audible differences, then a more "scientific", thorough and difficult test would be neccesary to know which is the weak link. But first, I'd like to know how audible is the whole actual process.

Edit: all the process was done with CoolEdit Pro 1.2a. I have to update the web page and add all this additional info.

soundcard challenge, opinions welcome.

Reply #7
I can't listen right now because I'm at work. The first thing I notice in your setup is that according to the graph, the soundcard has a -0.1 db response at 30 Hz, and -0.1 at about 15 kHz.

In my opinion, the loss of quality produced by the equalisation process will be much bigger than the loss of bass/treble itself. it would be interesting to test again without equalisation. I think it will be harder.

soundcard challenge, opinions welcome.

Reply #8
I think that a good-quality slight eq. doesn't have to produce any quality loss. In my case, The eq. is done digitally in 32 bit floating point format (FFT filter of CEP 1.2a), so there are no significant rounding errors = no added noise by the process. This eq. is phase linear, so there's no phase distortion. The only drawback is the increase of the background noise at the frequencies being boosted, but the eq. was of just about 0.4 dB max. boost at near 20 KHz frecuencies, so I think this increment of background noise is quite inaudible, even if repeated 4 times.

You point that there's a 0.1 dB rolloff at 15 KHz. the 4 times processed signal would have a 0.4 dB rolloff at 15 KHz, higher at higher frequencies. I think this rolloff may be audible for some people. But I doubt the effect of the equalisation can be so audible.

soundcard challenge, opinions welcome.

Reply #9
I have only received one test result so far. It would be interesting if some more people could send me their results, or just if they find the test hard or difficult. You can send e-mail to me in an anonymous manner, you know, just changing any data that can identify you at you e-mail software, before sending it.

My address is [a href='mailto:kikeg@arrakis.es'][/a]

According to what some audio purists say about quality of soundcards as opposed to high-end gear, importance of cables, distortion of digital, etc, it should be quite easy with a good quality equipment, to tell the original file from the 4th generation one.  You can burn the files to a cd and use the best equipment available to you to compare the files.

You know, I used a plain 150$ sound card and a 3-4$ interconnect. But for me and also for the other person who sent results, it is not as easy as it could seem at first.

soundcard challenge, opinions welcome.

Reply #10
I've updated the page with more info over the goals of the test and details over the generation of the files.

PLEASE ANYONE TRY IT AND LET ME KNOW!!!

 
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