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In Reply to: Re: I bought a Creative X-Fi Xtreme Music just for fun. posted by fmak on February 10, 2007 at 06:36:14:
I am not that familiar with predecessors to the X-fi.The X-fi ASIO mixer has level controls for individual channels, as well as a "master volume control" as so many ASIO capable software mixers do.
The individual channel levels go from 0-100%, but are at 0db in the seventy five percent position!
The master volume does not even indicate where 0db is... I need to investigate this further. When you install fresh drivers, it's set at some goofy number (I think 79%). I am going to post some queries on the expansive creative forums and see if anybody knows.
It's a very valid concern and something we do need to be aware of...
If a signal is not clipping, and suddenly you're clipping, then you know you have digital gain somewhere in the signal path.
Not good.
Follow Ups:
Interesting; this is a generic problem it seems. If you do a spectrum analysis at 80% or so, the distortion products are aweful.I wonder why Creative allows this? But it puts even more doubt on all those ravish(?) reviews that hadn't found thois problem, with beautiful measurement results.
Fmak:I did not do a spectrum analysis, but I did experiment with different input levels. When using ASIO, the input levels are spot on with files that have test tones at various reference levels (-6db, -12db etc.)
Could you please detail the test method and software you used for these tests?
I find it a bit of a long stretch that Creative has a single "damning and generic" flaw in all of their cards. The X-Fi may use tech from older cards (Audigy line), but when looking at the software and board layout you certainly get the "feeling" that not much was left alone when coming out with this product.
Truth be told, I am somewhat skepitcal of "gamer pros" who run software audio analyzers and cut and past results on the net. At the Rightmark site, Creative has their own "Test our card this way" guide which I ALSO find suspect. Why should someone who KNOWS how to use a RMAA use "special" level settings for their card? Why are they using 94% for output level? To prevent clipping? Reduce distortion perhaps? They tell us that 75% is 0db on the individual strips on the ASIO mixer. So what is 0db on the MASTER level control? It's in percent as well, but it does not display dB. When installing fresh drivers, the level control is not at 100% - I think it's at 79 or 80 percent I can't remember.
Something may be amiss here.
Allow me to make a subjective observation here: the levels of the X-fi seem solid, and when using Bit-Perfect mode and ASIO, I am hearing a pretty sweet sounding output. Since most music has levels that constantly slam against the 0db mark, I think if the Creative X-Fi had a glaring problem as you suggest... I would hear it! :o)
So my "final answer" (without 'phoning a friend' ha ha) is that if this problem was evident in the Audigy line, then I think it's probably not there in the X-fi line.
Let's discuss some test methods, shall we?
I don't use Rightmark which I had found to give optimistic results; I use Dr Jordon's Pro 64 bit FFT.For spdif eye pattern, I terminate into 75 Ohm on a 150 MHz/400Mhz scope.
Fmak:Interesting...Can the SPDIF eye pattern be used for determining clock jitter?
You get1. Picture of how well the spdif interface is constructed ie smooth eye pattern with no kinks or ground effects in the waveshape, and the rise time etc.
2. Qualitattive measure of time base variation ie jitter on a good wide band scope. I use a 400 MHz one. Indeed, very expensive scopes can be used to measure jitter.
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