QuantAsylum QA400 - Page 115 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

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 1st July 2014, 05:41 PM   #1141
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Yes I noted, in fact I subscribe to that thread.
It's just that right now I have another priority, but I have the same ideas to cut out some of the ss switches and the DC-opamps.

One issue I still am unsure about is how fast the autoranger needs to/can react. I guess I would still need the full range input protection for the soundcard this thing is going to feed. I'll burn that bridge when I get to it

Jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 18th July 2014, 11:52 PM   #1142
1audio is online now 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
I finally stepped up to the plate and ordered the PCB's to see if they will work. I made one last minute addition to the design. I added LME49610 buffers on the bottom of the board for the outputs. They are set up so they can be easily bypassed but I wanted to try them and see if they can enable a 50 Ohm drive in this.

Boards next week. Maybe some partly working boards soon after.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 19th July 2014, 07:38 PM   #1143
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Cool, looking forward to this
  Reply With Quote
Old 19th July 2014, 10:40 PM   #1144
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
Quote:
Originally Posted by 1audio View Post
I finally stepped up to the plate and ordered the PCB's to see if they will work. I made one last minute addition to the design. I added LME49610 buffers on the bottom of the board for the outputs. They are set up so they can be easily bypassed but I wanted to try them and see if they can enable a 50 Ohm drive in this.

Boards next week. Maybe some partly working boards soon after.
Is the chip inside the feedback loop?

I'm sure this can drive 50 ohms, no problem, but better if inside feedback loop. I use the BUF634 to drive 32 ohm headphones all the time. I used the TO-220 version with a big heatsink. No problems at all.
  Reply With Quote
Old 21st July 2014, 05:40 AM   #1145
1audio is online now 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
The buffer is inside the loop. Its designed to be used that way. I will be interested in how it all actually works once its all together. Datasheet promises .00005%. I won't expect that much from this. The goal is 3V open circuit and 1.5V into 50 Ohms but I'll check the board with 18V supplies with a goal of 7V into 50 Ohms (200 mA Peak)
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 22nd July 2014, 01:24 AM   #1146
diyAudio Member
 
dirkwright's Avatar
 
Join Date: May 2011
Location: Virginia
It'll probably get hot driving 7V into 50 ohms.
  Reply With Quote
Old 22nd July 2014, 03:45 AM   #1147
1audio is online now 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
The USB supply won't support 10V peak into 50 Ohms anyway. However for other possible projects with soundcards this may show some good options.

I prefer 50 Ohms when possible since cables, loading and stray cap won't alter the frequency response to any extent.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 22nd July 2014, 03:48 AM   #1148
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by 1audio View Post
The USB supply won't support 10V peak into 50 Ohms anyway. However for other possible projects with soundcards this may show some good options.

I prefer 50 Ohms when possible since cables, loading and stray cap won't alter the frequency response to any extent.
What about 75 ohm or 100 ohm?
__________________
David.
  Reply With Quote
Old 22nd July 2014, 03:55 AM   #1149
1audio is online now 1audio  United States
diyAudio Member
 
Join Date: Mar 2004
Location: SF Bay Area
Blog Entries: 3
I have a lot of 50 Ohm stuff. It will have the lowest noise as a source plus it will have the smallest error when loaded. Going up from 50 Ohms is easy.
__________________
Demian Martin
Product Design Services
  Reply With Quote
Old 22nd July 2014, 03:57 AM   #1150
davada is offline davada  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Fort St John, BC Canada
Quote:
Originally Posted by 1audio View Post
I have a lot of 50 Ohm stuff. It will have the lowest noise as a source plus it will have the smallest error when loaded. Going up from 50 Ohms is easy.
Good reason.
__________________
David.
  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



New To Site? Need Help?

All times are GMT. The time now is 11:39 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