Building a symmetrical psu B1 buffer - Page 260 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 28th February 2013, 10:06 AM   #2591
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by AndrewT View Post
The B1 has two switchable inputs. That's where the two sources connect.
Then the switches should feed the selected signal to the attenuator.
Finally the output of the attenuator is fed to the buffer since the attenuator cannot alone drive the cables to the power amplifier and/or the pre-amp..............
Quote:
Originally Posted by ckwong99 View Post
...................My concern is the order arrangement for the shunt type attenuator and B1 buffer. You know the shunt type attenuator drawback is vary of impedance to its next stage. Base on my situation, how following option is better deployment ?

Option 1) Source signal -> Shunt type attenuator -> B1 buffer -> Tube Preamp...................
__________________
regards Andrew T.
  Reply With Quote
Old 1st March 2013, 05:38 AM   #2592
diyAudio Member
 
Join Date: May 2005
Location: HK
Thank Andrew,

Do you know the optimal value of series resistor inside the shunt type attenuator ?

Now the kit come from 10K value installed but I think it is no assumption the user will apply a buffer behind it ....
  Reply With Quote
Old 16th March 2013, 10:05 AM   #2593
diyAudio Member
 
Join Date: Dec 2008
Default Lowering the output impedance?

I've read that the output impedance of the DCB1 is 260 ohms. The amplifier this will be connected to prefers around 50 ohm output of the pre-amp, although 1K ohm can be supported.

How could I lower (or raise) the output impedance to match the values above?

Thanks
  Reply With Quote
Old 16th March 2013, 10:47 AM   #2594
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
The output impedance is made up from a combination of the output resistor and the follower's output impedance.
You can change the output resistor for a lower value. But you must check that the adopted value does not allow the B1 to become unstable on fast changing signals/interference.
__________________
regards Andrew T.
  Reply With Quote
Old 16th March 2013, 05:16 PM   #2595
diyAudio Member
 
Join Date: Dec 2008
Is R4 the correct output resistor to change? If so, would it be a correct assumption to calculate the follower's output impedance as 260 - R4?

R4 = 220ohm, therefore the follower's output impedance is 40ohm

Without a scope, or test equipment (apart from a DMM), how could I check to see if a lower value is causing it to be unstable?

Thanks
  Reply With Quote
Old 17th March 2013, 12:03 PM   #2596
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
without a method for checking stability, stick with the 220r.

An Rs=260ohms is not bad (actually rather good) at driving a capacitive cable and reasonable Zin. Try 5m of 100pF cable into 20k Zin.
__________________
regards Andrew T.
  Reply With Quote
Old 2nd August 2013, 02:33 AM   #2597
diyAudio Member
 
Join Date: Jan 2011
Quote:
Originally Posted by Salas View Post
That layout is vintage of what later sprung to Mez and Hypno in their popular forms. Nice to see it done again and playing well. Watch turn off cycle mainly if to ever drive a DC coupled amp since there is no relay. Enjoy.
Salas, can you send me the EAGLE files ? I want to build it
  Reply With Quote
Old 2nd August 2013, 05:35 AM   #2598
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
I only had those print files I posted back then. You can find them in the first pages. That is the way he also did it in that link, graphical transfer.
  Reply With Quote
Old 10th August 2013, 02:45 PM   #2599
diyAudio Member
 
JOHN BALI's Avatar
 
Join Date: Jun 2010
Location: Near the Mountain
Default I want to etch this

Hi everyone,
I've read all post here from page 1 to last one... need some days

I want to use my own layout, please some comment before I go to etch it PCB
Maybe I miss something important...

Question:
Is that okay to use 2 + 3 LED's (bright one) instead of 3 + 5 LED's...?
(all I need is to match the voltage to 5.4v & 9v)

Regards
Attached Images
File Type: gif Dirrect placement.GIF (50.0 KB, 241 views)
File Type: jpg Top View.jpg (103.2 KB, 243 views)
Attached Files
File Type: pdf DCB1 john layout.pdf (74.0 KB, 46 views)
__________________
Thank you, I wish you happy
peace & G B U

Last edited by JOHN BALI; 10th August 2013 at 02:48 PM.
  Reply With Quote
Old 10th August 2013, 03:39 PM   #2600
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
I wouldn't pretend that I have the energy to scrutinize your layout for connections (40C here). Just make sure it follows the schematics accurately.
But others may spot something or not.
Unfortunately super bright LEDS have a reputation for being noisier than normal ones which I can not confirm how much right now.
But surely I have never seen them in instrumentation as voltage references. Better use 3mm generic reds or greens in the 3+5 proven configuration.
  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
New-building of my B1 buffer Babowana Pass Labs 328 20th February 2010 01:14 AM


New To Site? Need Help?

All times are GMT. The time now is 12:58 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