Test & Measurement interface for Soundcard - Page 61 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 31st August 2012, 08:08 AM   #601
diyAudio Member
 
Join Date: Aug 2008
Hi, AndrewL,

No problem, but I can do it only tomorrow.
BTW, I don't have foil shield inside yet.
  Reply With Quote
Old 1st September 2012, 04:36 PM   #602
diyAudio Member
 
Join Date: Aug 2008
Quote:
Originally Posted by AndrewL View Post
Hi Linksguru
Could you post an picture of the inside of your box?
Andrew
Hi, AndrewL,

Here are the pictures of assembled PCB.
Additionally, as many forum members suggested, I grounded shaft of rotary switch, 50 Hz noise went down by -4dB. Closest ground point is R11 (see red wire on photo).

Test in loopback mode (input and output connected together on 33K resistor terminals), 1.9V sound card out, 96KHz, attached.
Attached Images
File Type: jpg _DSF0245.JPG (231.4 KB, 333 views)
File Type: jpg _DSF0246.JPG (180.1 KB, 321 views)
File Type: jpg SCI-Loopback-96K-1.9V-THD-1KHz.jpg (168.3 KB, 318 views)

Last edited by LinuksGuru; 1st September 2012 at 04:38 PM.
  Reply With Quote
Old 1st September 2012, 04:58 PM   #603
diyAudio Member
 
Join Date: Aug 2008
I would like to add a not to ESI Juli users. Although sound card itself is very good, its seems it works better (in this particular application) in 96KHz, not 192 KHz mode. I don't know why, I suspect high-frequency noise picked up by SCI.

So next step will be to building foil shield inside plastic box.

At a glance, precision looks very good (0.0025% THD, 0.014% THD + N @ 1.9V/1KHz), but it is actually not so. Due to the noise (or some other reasons), it is not possible to precisely measure THD at small signal level, e.g. 20mV, and precision at 20 KHz limited to 0.05%.

I'm attaching tests in loopback mode, 20Hz - 1KHz - 20KHz, 1.9V output from ESI Juli (balanced connection), 96KHz sampling rate.
Attached Images
File Type: jpg SCI-Loopback-96K-1.9V-THD-20Hz.jpg (169.8 KB, 306 views)
File Type: jpg SCI-Loopback-96K-1.9V-THD-1KHz.jpg (168.3 KB, 294 views)
File Type: jpg SCI-Loopback-96K-1.9V-THD-20KHz.jpg (168.9 KB, 86 views)
File Type: jpg SCI-Loopback-96K-1.9V-IMD.jpg (174.0 KB, 89 views)
  Reply With Quote
Old 1st September 2012, 07:33 PM   #604
klewis is offline klewis  United States
diyAudio Member
 
klewis's Avatar
 
Join Date: Sep 2007
Blog Entries: 36
Quote:
Originally Posted by LinuksGuru View Post
I would like to add a not to ESI Juli users. Although sound card itself is very good, its seems it works better (in this particular application) in 96KHz, not 192 KHz mode. I don't know why, I suspect high-frequency noise picked up by SCI.

So next step will be to building foil shield inside plastic box.

At a glance, precision looks very good (0.0025% THD, 0.014% THD + N @ 1.9V/1KHz), but it is actually not so. Due to the noise (or some other reasons), it is not possible to precisely measure THD at small signal level, e.g. 20mV, and precision at 20 KHz limited to 0.05%.

I'm attaching tests in loopback mode, 20Hz - 1KHz - 20KHz, 1.9V output from ESI Juli (balanced connection), 96KHz sampling rate.
At 96khz you should be able to measure out to about 45khz. At 192khz, out to about 90khz. There is a setting in Arta that will allow you to expand you window to view these higher frequencies.

Second, learn to used the averages function for fft. It will smooth your response lines. I would Start with 25 averages.

Ken
  Reply With Quote
Old 1st September 2012, 08:39 PM   #605
diyAudio Member
 
Join Date: Aug 2008
Quote:
Originally Posted by klewis View Post
At 96khz you should be able to measure out to about 45khz. At 192khz, out to about 90khz. There is a setting in Arta that will allow you to expand you window to view these higher frequencies.

Second, learn to used the averages function for fft. It will smooth your response lines. I would Start with 25 averages.
I know about expanding graph ranges/window - if you look at my attachment, they display charts in 10Hz - 30KHz ranges instead of standard 20Hz-20KHz.

Averaging turned on - it is clearly visible on top menu bar.
  Reply With Quote
Old 1st September 2012, 09:18 PM   #606
TheGimp is online now TheGimp  United States
diyAudio Member
 
TheGimp's Avatar
 
Join Date: Aug 2009
Location: Johnson City, TN
A better choice for shielding is Mu Metal (I used UltraPerm) instead of Al foil. Al foil will work as an electrostatic shield, but not a magnetic one. Ultraperm is available from the usual source (ebay) at a reasonable cost.

Just be careful with Mu Metal shield. You don't want to bend it or the stress reduces the permeability from the annealed state. It cuts with a heavy pair of scissors.
  Reply With Quote
Old 2nd September 2012, 12:46 AM   #607
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
Quote:
Originally Posted by TheGimp View Post
A better choice for shielding is Mu Metal (I used UltraPerm) instead of Al foil. Al foil will work as an electrostatic shield, but not a magnetic one. Ultraperm is available from the usual source (ebay) at a reasonable cost.

Just be careful with Mu Metal shield. You don't want to bend it or the stress reduces the permeability from the annealed state. It cuts with a heavy pair of scissors.
You can get ultraperm on eBay. In the past, it's been available at the electronic goldmine. It's self stick mu metal.
  Reply With Quote
Old 2nd September 2012, 08:26 AM   #608
AndrewL is offline AndrewL  United Kingdom
diyAudio Member
 
Join Date: Nov 2005
I like the Jukli@ but couldn't get the averaging working relaibly enough, to much driver latency; it could have been the PC. I wanted to free up the PCI slot anyway so I switched to an EMU 1212 PCIe. Patchmix driver control is not intuitive so it took a while to set up correctly, but it seems very fast now, no latentcy problemes.

Andrew
  Reply With Quote
Old 2nd September 2012, 08:55 AM   #609
diyAudio Member
 
Join Date: Aug 2008
Quote:
Originally Posted by AndrewL View Post
I like the Jukli@ but couldn't get the averaging working relaibly enough, to much driver latency; it could have been the PC. I wanted to free up the PCI slot anyway so I switched to an EMU 1212 PCIe. Patchmix driver control is not intuitive so it took a while to set up correctly, but it seems very fast now, no latentcy problemes.
Andrew
Nope, its not PC. I have Quad Core with 4GB RAM. It looks like a driver latency problem, you can see it on my charts attached, averaging doesn't work well.

BTW, did you solved oscillation/noise problem with SCI?

Last edited by LinuksGuru; 2nd September 2012 at 08:57 AM.
  Reply With Quote
Old 2nd September 2012, 12:49 PM   #610
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
Quote:
Originally Posted by TheGimp View Post
A better choice for shielding is Mu Metal (I used UltraPerm) instead of Al foil. Al foil will work as an electrostatic shield, but not a magnetic one. Ultraperm is available from the usual source (ebay) at a reasonable cost.

Just be careful with Mu Metal shield. You don't want to bend it or the stress reduces the permeability from the annealed state. It cuts with a heavy pair of scissors.
The board does have a ground plane in it, so I guess extra shielding may not be completely necessary.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Recommendations on pc audio interface for loudspeaker measurement diypole Multi-Way 9 15th July 2009 12:45 PM
Request for advice / high performance soundcard for measurement Gordy Solid State 8 14th February 2008 04:14 PM
MCM Speaker Measurement Interface / USB Woofer Tester sdclc126 Multi-Way 0 17th January 2007 01:00 AM
Tenma Speaker Measurement Interface johngalt47 Multi-Way 1 6th January 2007 02:17 AM
Soundcard interface. Mr Evil Everything Else 5 12th July 2005 11:38 PM


New To Site? Need Help?

All times are GMT. The time now is 07:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2