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Old 16th December 2010, 01:24 AM   #21
SY is offline SY  United States
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Quote:
Originally Posted by Trevor White View Post
Also every CD ever sold comes with built in quantisation errors due to the finite resolution of the binary number system and there is nothing you can do about it no matter how good you think your analog reproduction system is !!
No. Dither.
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Old 16th December 2010, 01:27 AM   #22
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BTW, I think that there was a problem with the stock unit judging from the frequency response.
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Old 16th December 2010, 01:40 AM   #23
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Originally Posted by MurphyUHF10 View Post
It was my modified DCX that we took along to these listening tests,, and to be honest I had expectations that the modified DCX, with all its upgrades, would out perform stock DCX and miniDSP.. In actual fact they pretty much all sounded the same!! (to me anyway..)
Thanks for the honest evaluation
I can't say that I'm surprised by the outcome.
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Old 16th December 2010, 02:24 AM   #24
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Hi, Paul S.,

I live in Melbourne I am interested in the next(if there is one) evaluation/comparison of DCX, MinDSP and DEQX. I have a DCX2496 and I can bring it along if you like. So far your comparison is most interesting.

You can contact me using the email address from my profile.

Cheers.
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Old 16th December 2010, 04:03 AM   #25
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Originally Posted by qusp View Post
right, see this is where systems like the sabre's integrated digital volume are a different ballgame, the attenuation is done in the dac registers themselves. I use this for my 2 channel rigs with overwhelming superiority to analogue to my ears and shortly the 8 channel ackodac will allow this sort of system for crossovers. this is where i'm headed also adjusting the gain in the spdif stream itself pre-dac is transparent with something like an RME9652
I like the sounds of that!!

:-)
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Old 16th December 2010, 04:31 AM   #26
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tan,

I'm not sure if we will do any more. Keith who is getting the Marchland has determined that the DSP units don't work in his system and the remaining 4 of us DIY guys - I'd say we all agree that the differences between the units were not big enough for us to want to give it more time. All of us are experimenting with waveguides (or planning to) and I think at this point we'll be more interested in that side of things.

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In other words this is not a valid test. It is just a whole lot of subjective opinions from people who may or may not have a preconceived bias. I'd hardly call that conclusive
Trevor,

It isn't quite so black and white. It's easy to think that from a distance. I wrote a blog post recently about a major flaw with many blind tests:

Red Spade Audio: The biggest problem with blind testing

Please keep in mind that in general I'm in favour of blind testing. The problem is that normally in a blind test, you rely on audio memory. This is a bigger limitation than listener bias in many cases.

If everyone came away from the tests with their opinions completely unchanged, then you might have a point. I was not overly concerned with listener bias - I know the guys in the test and their biases reasonably well.

Keith expected to easily hear differences and he did. We even tested him blind and it was obvious to all that he could in fact hear and describe what he heard. Turns out he has some good listening skills. Once he hears something he zeroes in on that and blocks out everything else.

Murphy owned the modded DCX and felt in his system it was clearly superior, but admitted in the sighted tests that he felt they sounded the same. His bias didn't stop him from coming away with a very different opinion.

Gainphile - if I had to guess I'd say that he wasn't expecting to hear much if anything and his impressions seemed to back that up. If anything his bias may be preventing him from hearing very subtle things - the more you believe, the more you are likely to listen for small differences.

Antripodean - I'd say our opinions here are probably the closest, both of us expecting that differences will be subtle if present at all.

I did hear some differences, but they were the kind that would normally run under the radar. If I have to listen very critically, then it's subtle and I'm not that interested.

Which of these biases makes the test invalid?

If we had a stronger subjectivist contingent full of strong "cable believers" then I'd be wanting to make the test blind and more rigorous. However, even in that case, the instant switching is very revealing. I've seen people change their bias rather than hang onto them when instant switching is done.

Would you have considered it valid had we done a blind test but still had audio memory to content with? I would argue that this invalidates such a test to a greater degree if you are dealing with subtle differences. Put simply, we can't recall sounds with sufficient precision to compare a sound we hear presently to one we remember, even if there is only a one second pause. It will only work for easy to pick differences.

We did at times test blind, but in general it was technically a sighted test. Keep in mind that unless you are mentally tracking which is switched at the time, most of the time you don't actually know which ones is being played.

Due to the revealing nature of the switching method, I consider blind or not to be a minor factor. You are listening for any difference at the point of switching, so we switched frequently, sometimes 5 seconds apart.

I'd encourage people to try their own tests and make the effort to set up instant switching. If you do I think you will conclude as I have that it makes the comparison much easier and the need to test it blind becomes moot.

The second test was conclusive about one thing - the differences were not huge. They were at that level where some claim to hear a difference while others don't. That is enough conclusion for me. It tells me that my time is better focused elsewhere.

The tests weren't set up to be "statistically significant." They were informal in nature and intended to satisfy the curiousity of the participants. Afterwards I decided to share the results because I realise it's of great interest to many other diyers who mostly haven't had the luxury of comparing active crossovers in this way.
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Old 16th December 2010, 06:44 AM   #27
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Quote:
Originally Posted by qusp View Post
right, see this is where systems like the sabre's integrated digital volume are a different ballgame, the attenuation is done in the dac registers themselves. I use this for my 2 channel rigs with overwhelming superiority to analogue to my ears and shortly the 8 channel ackodac will allow this sort of system for crossovers. this is where i'm headed also adjusting the gain in the spdif stream itself pre-dac is transparent with something like an RME9652
qusp, I have an RME FF400..... what makes the digital attenuation in the RME cards better than that in (eg.) miniDSP?

Also, can you give us the gist of the 8 channel ackodac?
eg. input connectivity, price, balanced outs? etc.
I assume it's the akd18 listed on the ackodac site, but a search for that term yields nothing.

Thanks!
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Old 16th December 2010, 06:48 AM   #28
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Oh, and do they pop at their outputs when switched on/off?
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Old 16th December 2010, 07:20 AM   #29
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Quote:
Originally Posted by paulspencer View Post
The problem is that normally in a blind test, you rely on audio memory. This is a bigger limitation than listener bias in many cases.


So, audio memory is a problem May i ask if this is indeed the case, what is the point of improving one's system? Do you constantly click an A/B switch when listening for pleasure? Or you simply enjoy the warm feeling that this has been proven in an A/B comparison to be a better system? A mystery to me. Yet, another example that speaker guys listen and hear differently to amplifier/dac guys. Btw, your switching box looks like a prop from a horror movie to me. It could well be everything sounds the same through it.
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Old 16th December 2010, 02:36 PM   #30
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I'm with you one this one, Paul. Having been involved in a lot of public listening tests over the past few years, IMO listener bias is over rated. It exists, but isn't the huge problem so many folks think it is.

But that's a topic for another thread!
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