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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 29th March 2013, 02:57 PM   #37521
BV is offline BV  Slovakia
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Quote:
I am interested in a diy way of estimating jitter “quantity” in audio equipment (calibrating in standard terms is not of my concern)
DIY way.. Vertical axis is relative level of unwanted "artifacts" in Dunn (J-test) spectra..
Attached Images
File Type: png jitter.png (11.5 KB, 173 views)
 
Old 29th March 2013, 02:58 PM   #37522
simon7000 is offline simon7000  United States
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The Meitner Interview is 20 years old! It's nice to know DIY has caught up.
 
Old 29th March 2013, 03:03 PM   #37523
Esperado is offline Esperado  France
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Quote:
Originally Posted by jacco vermeulen View Post
You know Mr Curl, I've been trespassing this thread from week one, mentioned a zillion times that you should be treated with some respect,
Stay consistent, please.
 
Old 29th March 2013, 03:11 PM   #37524
qusp is offline qusp  Australia
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Originally Posted by simon7000 View Post
The Meitner Interview is 20 years old! It's nice to know DIY has caught up.
OK I didnt look at the date, I presumed something being linked here for conversation was recent. OK well 20years ago it was obviously quite forward thinking, but no way was it equal to what is being done today; the technology just wasnt there.

I notice he never did what he said was just around the corner 20years ago...

I have however seen and used one of his more recent olive workstations (if hes still involved with them). it was a huge, expensive, clunky, closed system that was bettered by the laptop based system next to it.

I have been told the recent meitner dac is quite good though, but its just a plain vanilla dac.

Last edited by qusp; 29th March 2013 at 03:19 PM.
 
Old 29th March 2013, 03:17 PM   #37525
PMA is offline PMA  Europe
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John Curl's Blowtorch preamplifier part II
Jacco, internet discussion is not the best way how to evaluate sound quality .
 
Old 29th March 2013, 03:26 PM   #37526
Esperado is offline Esperado  France
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Originally Posted by PMA View Post
Jacco, internet discussion is not the best way how to evaluate sound quality .
While it can help to figure out how abyssal can be noise/signal and distortion ratios.
 
Old 29th March 2013, 03:34 PM   #37527
elektroj is offline elektroj  Europe
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Originally Posted by qusp View Post
the presence and height/spread of harmonics/sidebands next to the base of the fundamental is the indication of jitter. 1audio/Demian has access to higher end kit and more experience measuring jitter than just about anyone on this forum...
LOL! You guys don't even recognize when someone's making fun of you.

That spectragram that 1audio showed is meaningless! What about reducing the frequency span for a starters? i.e. zooming in on the center frequency..

For comparision - I just fed 9978 Hz sine to the analog input of an oldish "plain vanilla" Digidesign sound card residing in this same computer I'm typing this text on. The card itself is nothing fancy - 74HCU04 oscillator with off the shelf 48MHz crystal, residing in "harsh" enviroment and fed from the switched PSU.
Details on the settings are seen in the picture. I made the span as small as possible and activated 64 Bit analysis (see how "deep down" the analyzer can "look", if fed with the appropriate source + sufficiently low noise floor).

Do we see any sidebands? None! Nada! Zilch! It didn't matter in my case whether I used Hanning. Hamming, Triangular or Rectangular window.

What I am trying to say with all this - one has to have very low noise floor and/or very jittery clock feeding the A to D converter chip to see any sidebands by testing it with the signal fed to its input. If you see any that means the A to D converter is no good.

I'm affraid, it takes the specialized equipment ($$) to do any serious jitter measurements. I have a 43MS/s 25ps resolution analyzer here and even that is sometimes not "good enough" (right picture, for illustration only).

Best,
Attached Images
File Type: jpg no_sidebands.jpg (258.0 KB, 173 views)
File Type: jpg 11MHz_hist.jpg (105.2 KB, 159 views)

Last edited by elektroj; 29th March 2013 at 03:45 PM.
 
Old 29th March 2013, 03:35 PM   #37528
elektroj is offline elektroj  Europe
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Quote:
Originally Posted by gpapag View Post
I am interested in a diy way of estimating jitter “quantity” in audio equipment (calibrating in standard terms is not of my concern).
George, take a look at this approach:
DAC Overview

Best,
 
Old 29th March 2013, 03:38 PM   #37529
1audio is offline 1audio  United States
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John Curl's Blowtorch preamplifier part II
Quote:
Originally Posted by simon7000 View Post
Demian,

I got another denizen of this loony bin to solve my jitter issue. But where did you learn the trick of using an FM detector? (I need to have real numbers to present rather than I tweak it a bit.)

ES
Someone here mentioned it and I took the bait. It turns out to be more involved than it might seem. I posted my incomplete notes here on using a tuner: http://www.diyaudio.com/forums/blogs...-analysis.html

What kind of numbers did you get for jitter?
__________________
Demian Martin
Product Design Services
 
Old 29th March 2013, 03:56 PM   #37530
qusp is offline qusp  Australia
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Originally Posted by elektroj View Post
LOL! You guys don't even recognize when someone's making fun of you.

That spectragram that 1audio showed is meaningless! snip...
umm, maybe thats because your post was pretty obtuse and you have gone on to mention a system you have that is orders of magnitude worse than the system I mentioned in the post previous to yours... so good on you!! you scored a point...less

the system I linked was 8Gb/s 2ps.. its not cheap, but can be had for less than the $10K mentioned.

I gather Demian could probably zoom in... I gather its not the system he has at work... i'll let him combat you though, since that appears to be what you want...


@ simon:

it seems the latest meitner top of the line EMM labs dac uses basically exactly the same technology I was talking about thats available here on the forum to eliminate jitter, except the EMM version (called MFAST) does up to 24/192 vs 32/384 for the $250 i2s fifo buffer/DSP available here. no digital crossover systems to be seen anywhere in the pages

clearly the man knows what hes doing and has advanced the technology in the marketplace, but any company that has to come up with a marketing acronym/trademark/buzzword for every... single... function... turns me off a bit and he has simply continued to build on what I was talking about.

Quote:
• MFAST™ asynchronous technology for instant signal acquisition, jitter-free
performance
• MDAT™ signal processing technology:
• Provides 2x DSD upsampling for PCM playback
• Preserves phase, frequency and dynamic integrity of the waveform
• MDAC™ discrete dual differential D-to-A conversion circuit
• MCLK™ high-purity master clock that establishes new benchmarks in jitter
performance
he even has to make a real abbreviation into a trademark acronym

at least on spec, the dac i've built, mostly from assorted PCBs and modules bought here and some tweaks of my own, equals or betters every spec on paper and sounds great to me. bear in mind its taken 2 years and cost over $4K for a quad mono ES9018 dac that actually IS built to function as the front end for a 2 way digital crossover that can be controlled via ipad

edit: actually not quad mono only 2 x ESS dacs, each DAC is used for a 'mono' 2 way balanced output for the L or R channel, instead of a stereo output, so I suppose its kinda dual stereo balanced, but the dac power supply, analogue stages and the amps are quad mono balanced.

that someone like me can put together such a system, with a lot of learning along the way, speaks of where the DIY scene is now.

maybe all this annoying marketing fluff speaks more of the consumers, but at any rate its pretty comedic.

Last edited by qusp; 29th March 2013 at 04:17 PM.
 

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