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

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Salas hotrodded blue DCB1 build
Salas hotrodded blue DCB1 build
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 15th September 2010, 10:26 AM   #331
wendell c is offline wendell c  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Las Vegas
Salas, i did as you suggested the 39r are underneath the board and used the 10r in lieu of the 8r2 since the ones I had were 8k2 by mistake. The voltage of 2nd cap is 23v & -24.8v.

I'm not sure if this is the correct reading you want for the audio out offset, but I measured from ground to out and it is 0.002v.

Only using the teddy reg since I have boards on hand already built with few minor changes to resistor values, I would prefer the salas mini shunt and I do have the board from quangho but not the parts.
  Reply With Quote
Old 15th September 2010, 10:33 AM   #332
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by wendell c View Post
I'm not sure if this is the correct reading you want for the audio out offset, but I measured from ground to out and it is 0.002v.
0.002V = 2mV
That is unusually high for a DCB1 build.

How accurate is the voltage scale of your DMM?

It is good to have a meter that can read 199.9mVdc and can also read 199.9mVac. these can be bought cheaply with <=+-0.5%+-1digit accuracy.
+-1%+-2digits should be very cheap and the worst you should buy.
__________________
regards Andrew T.
  Reply With Quote
Old 15th September 2010, 10:36 AM   #333
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas hotrodded blue DCB1 build
One English guy using an optivol recommended taking out the local 317 and just using a v1 dedicated reg for that as his best, after he used it as pre reg even.

Your Vin is not bad for 35V filter caps. With 8R2 it will give more mA and drop also. But it works fine as for now. 2mV is good enough offset for no problems but it can go lower.
  Reply With Quote
Old 15th September 2010, 10:42 AM   #334
wendell c is offline wendell c  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Las Vegas
Andrew, using a cheap little DMM. I tested again with a chinese fluke copy and I am getting 1.8mv and 0.2mv
  Reply With Quote
Old 15th September 2010, 10:57 AM   #335
wendell c is offline wendell c  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Las Vegas
Now, with ok from Salas. I need to figure the best way to implement the LDR. I've read in previous posts some people having noise or hum. I have both oliver and uriah boards, Does anyone have a diagram of how to connect the LDR to the DCB1.

Much appreciated!
  Reply With Quote
Old 15th September 2010, 11:08 AM   #336
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
0.2mV is good. That offset is typical of well selected Idss pairs.
1.8mV is poor for a selected pair. This low output offset will not damage any following equipment.
Will the following equipment multiply that 1.8mV to a value that could interfere with performance? An AC coupled power amplifier will accept 1.8mV of offset without any problem.
__________________
regards Andrew T.
  Reply With Quote
Old 15th September 2010, 11:11 AM   #337
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by wendell c View Post
I need to figure the best way to implement the LDR. ........... I have both oliver and uriah boards,
the originator of the Lightspeed volume attenuator says that the LED/LDR alone will perform better than an LED/LDR + buffer when following his design. You must decide if that applies to your implementation.
__________________
regards Andrew T.
  Reply With Quote
Old 15th September 2010, 11:24 AM   #338
wendell c is offline wendell c  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Las Vegas
Andrew, so it's better to just use a volume pot for the DCB1? the LDR alone is superior to the DCB1? I'm assuming you are talking about if buffer is not needed,yes?
  Reply With Quote
Old 15th September 2010, 11:55 AM   #339
Marra is offline Marra  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Near Lincoln
Salas hotrodded blue DCB1 build
I have just installed my transformer with 0-15v secondaries but with everything fired up its outputting 17v is this a problem?
  Reply With Quote
Old 15th September 2010, 12:06 PM   #340
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas hotrodded blue DCB1 build
Where is the 17V? On filter caps? Or is your AC? How much is the DC on filter caps?
  Reply With Quote

Reply


Salas hotrodded blue DCB1 buildHide 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
dcb1 buffer with shunt reg. merlin2069er Swap Meet 0 3rd August 2010 05:25 PM
F2 and DCB1 parts selection - please advice! DQ Pass Labs 6 25th November 2009 03:20 PM
Y B Blue - how blue LED improves the CD playback Peter Daniel Digital Source 176 25th September 2003 07:40 AM


New To Site? Need Help?

All times are GMT. The time now is 05:44 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