Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Equipment & Tools From test equipment to hand tools

QuantAsylum QA400 and QA401
QuantAsylum QA400 and QA401
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th November 2013, 06:57 PM   #501
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
QuantAsylum QA400 and QA401
I think this will illustrate what I'm asking:
Attached Images
File Type: png Test setup.PNG (7.2 KB, 430 views)
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 19th November 2013, 08:31 PM   #502
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
QuantAsylum QA400 and QA401
Quote:
Originally Posted by 1audio View Post
I think this will illustrate what I'm asking:
The gen used was a 600 Ohm output Z (HP 339A)....
?

-RM
  Reply With Quote
Old 19th November 2013, 09:57 PM   #503
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
QuantAsylum QA400 and QA401
The point being that the QA400 etc. will introduce distortion at its input. You can measure the distortion introduced by the input of the QA400 (or whatever) with this test.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 19th November 2013, 10:10 PM   #504
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
QuantAsylum QA400 and QA401
I will do that test and let everyone know if any change due to QA400 input loading and put up data here.

Thx-RNMarsh
  Reply With Quote
Old 20th November 2013, 06:39 AM   #505
RNMarsh is offline RNMarsh  United States
diyAudio Member
 
RNMarsh's Avatar
 
Join Date: May 2012
Location: 2457 Cascade Trail; Cool, CA. 95614
QuantAsylum QA400 and QA401
Default comparison A-P vs QA400

Using the ShibaSoku AG16 source (600 ohms/.7v rms), the QA400 added .0001% THD+N when applied in parallel with Audio-Precision 2722.

That is when the QA400 is in data acquisition mode... when halted and you have only the screen capture display, the THD+N is 2-3%.

The AG16 shows on the A-P as only having 2H and 3H at about -120dB and nothing above the noise floor of -135dB above those two harmonics.

The QA400 however, shows a lot of harmonics and extrainious freqs beyond the first two harmonics and shows the 2H and 3h at a higher level than the A-P.

RNM


DSC01190.jpg

A-P with Shibasoku AG16.jpg

QA400 with ShibaSoku Ag16.jpg

Last edited by RNMarsh; 20th November 2013 at 06:57 AM.
  Reply With Quote
Old 20th November 2013, 12:47 PM   #506
stellavox is offline stellavox  United States
diyAudio Member
 
Join Date: Jan 2007
Location: Oneonta, NY; USA
If the "stock" '400 input and output stages may be the "weak link" in an otherwise excellent product, how about adapting/modifying the outboard I/O stage that Demian has already developed to "tap into and replace" the stock I/O amps?

Charles
  Reply With Quote
Old 20th November 2013, 01:37 PM   #507
jan.didden is online now jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: The great city of Turnhout, BE
It may be enough to make sure the QA400 input is driven from a very low impedance, i.e. a buffer.
Many opamps show somewhat nonlinear input impedance and that may become a factor at the very low distortion levels we are looking at here.
Possible Demian's interface is better in this respect?

Jan
__________________
Music is dither to the brain; lets me think below the usual chaos - me
Get more Linear Audio for less! Check out my Autoranger and SilentSwitcher
  Reply With Quote
Old 20th November 2013, 02:15 PM   #508
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
I suspect the ESI chip and possibly the input blocking capacitor. it would be interesting to see
what we have with these parts removed or replaced.
__________________
David.
  Reply With Quote
Old 20th November 2013, 04:36 PM   #509
jan.didden is online now jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: The great city of Turnhout, BE
David, what is this ESI chip - is it the input opamp/buffer or what?

jan
__________________
Music is dither to the brain; lets me think below the usual chaos - me
Get more Linear Audio for less! Check out my Autoranger and SilentSwitcher
  Reply With Quote
Old 20th November 2013, 04:55 PM   #510
1audio is offline 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
QuantAsylum QA400 and QA401
I saw the input induced distortion as well. The interface reduces it but has a similar problem of its own. However the interface does reduce the extraneous spurs.

Adding a buffer/driver to replace the one on the board could work but its still more stuff to deal with. That only makes sense when the interface is inside the box. Connecting flying leads to holes vacated by the BNC connectors is easy. Flying wired to pads on surface mount PCB's demands an additional level of skill. Also, ideal would be an integrated diff in to diff out solution like the one I'm using. Otherwise it will need a number of .1% resistors to have decent common mode rejection.
__________________
Demian Martin
Product Design Services
  Reply With Quote

Reply


QuantAsylum QA400 and QA401Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
QuantAsylum 401 & 405 B&W_arthur Equipment & Tools 5 22nd March 2016 05:27 PM
QA190 and QA400 Gains sgtnoah Equipment & Tools 4 17th July 2015 04:46 AM
Question on QA400 Alan0354 Equipment & Tools 7 10th July 2015 07:34 PM
FS QuantAsylum QA400 audio analyser jan.didden Swap Meet 3 29th September 2014 06:10 PM
New Quantasylum QA190 Differential Input Probe stellavox Equipment & Tools 3 20th March 2014 07:06 PM


New To Site? Need Help?

All times are GMT. The time now is 09:32 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki