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Old 8th January 2010, 10:26 AM   #2221
Legis is offline Legis  Finland
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Quote:
Originally Posted by sendler View Post
How did we go from this post where it is reported that the stock DCX measures poorly, as high as .1% THD at higher frequencies of sweeps,
.
http://www.diyaudio.com/forums/multi...ml#post2008048
.
to the current discussion that favors the view point that it measures well and has no room for improvement?
I guess many people missed the posts of his measurements.
Did you read previous linked test at all? Increased THD in higher frequencies is a false accusation: Google Käännä

"The distortions do not vary significantly over the frequency." Also graphs show nearly identical THD% with all used frequencies (20Hz, 1kHz, 20kHz). THD is below 0,01 with all mentioned frequencies between 0,5Vrms - 9,7Vrms. The very first graps ("Frequency response + distortion on the frequency:") shows nearly straight line (between 10Hz - 50kHz) of THD at 1Vrms (1Veff). Please stop spreding wrong information (includes also others).

I think there is not that great variance between DCXs, so it would seem that the test you refer to, was done wrong. Opinions?

Last edited by Legis; 8th January 2010 at 10:34 AM.
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Old 8th January 2010, 04:08 PM   #2222
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Default 240 volt power?

Can someone in the USA please tell me if their DCX says it takes 240 volt power on the rear panel? Manual says "Internal switch-mode power supply for maximum flexibility (100 - 240 V~)" yet it seems they have released a version for each continent. Any reason to think one for the USA wouldnt work in Australia (240V)?

Last edited by JoeM; 8th January 2010 at 04:16 PM.
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Old 8th January 2010, 04:15 PM   #2223
SQLGuy is offline SQLGuy  United States
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Yes it does. You can see for yourself here: http://cachepe.zzounds.com/media/qua...95793116a5.jpg
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Old 8th January 2010, 04:19 PM   #2224
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Sorry, just edited my post while you sent that.....

That does say 85-240 but it also says Europe. I wonder if it's just the power cord that's different?
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Old 8th January 2010, 04:30 PM   #2225
Pano is offline Pano  United States
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It's an IEC cord, so yes.
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Old 8th January 2010, 05:07 PM   #2226
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Hmmm, just got a reply from a shop in the US who said his unit is 110V. Of course that was 5 mins after I pulled the trigger on ebay...
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Old 8th January 2010, 05:17 PM   #2227
SQLGuy is offline SQLGuy  United States
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Mine has the 85 - 240 Volt markings on it. I RUN it off of 110V, but it's a fairly generic SMPS, that can take pretty much anything as input.

Is the shop you're dealing with selling modded units with linear power supplies? I could see those as being fixed-voltage.
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Old 8th January 2010, 05:28 PM   #2228
SY is offline SY  United States
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Quote:
Don't think you are on the right track regarding jitter outcome – but how you think this comes down to harmonics ??
- and what else you think could be affected by jitter other than AD or DA conversion ???
If you distort a signal, you get harmonics- it is exactly analogous to a linearity error. See Bob Adams's JAES paper on the effects of jitter.

As to your second question, as long as the jitter isn't pathological (e.g., larger than the reciprocal of bit-rate), then the A/D and D/A jitter is all that affects the analog output signal. Jitter there causes distortion- again, see Adams's paper on the effect of jitter on the distortion of various types of D/A converters.
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Old 8th January 2010, 07:03 PM   #2229
mige0 is offline mige0  Austria
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Quote:
Originally Posted by SY View Post
If you distort a signal, you get harmonics- it is exactly analogous to a linearity error. See Bob Adams's JAES paper on the effects of jitter.

As to your second question, as long as the jitter isn't pathological (e.g., larger than the reciprocal of bit-rate), then the A/D and D/A jitter is all that affects the analog output signal. Jitter there causes distortion- again, see Adams's paper on the effect of jitter on the distortion of various types of D/A converters.
Hi Sy
still don't think its correct to refer to jitter as kinda harmonics - maybe with the exception of very special cases - do you have that paper you mentioned and could you possibly make it available to me?

Basically jitter is better described by a smear in the frequency domain IMO - especially when caused by pure noise. You'll find a paper on my page if you are further interested.
In simple explanation, distortion by jitter is in the style of Doppler intermodulation rather than harmonics.

Bottom line of my findings regarding jitter is that it can't be avoided – just minimised (same as Doppler IM by the way).
And second, that any meaningful digital resolution regarding bit depth is simply limited by jitter.
This makes it very unlikely that we soon will see a step towards 32 bit sampling rate that really *is* 32 bit .


My question regarding what else than AD / DA conversion could be affected was more rhetorically....
I am not familiar with "pathological jitter" you mention and in fact I have no clue what else than AD or DA conversion ever cold be affected by jitter. This - of course - also includes sample rate converters !


################

On the other hand - I entered the discussion here at the point where analog versus digital volume adjustment was the topic – seems there is no long lasting interest in this ?


Michael

Last edited by mige0; 8th January 2010 at 07:18 PM.
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Old 8th January 2010, 09:12 PM   #2230
Legis is offline Legis  Finland
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DCX2496

Could someone comment on these mods, they seem not too expensive since pound's exchange rate to Euros is quite good. Are they any good? I'm considering that I might buy my second DCX with mods so I would be able to compare unmodded and modded. If there is some site that offers similar mods for cheaper, someone could throw a link.

Are there any downsides to output/input mods like that, when the whole board is removed. What happens to servo-balanced inputs? Is the input balanced or unbalanced after removing the board?
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