B1 Buffer Preamp - Page 155 - 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 29th March 2009, 01:06 AM   #1541
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Quote:
Originally posted by maxlorenz
Hi Salas,



Avoiding crossover distortion and "coloring" the sound at our liking?

I've been told that some Tube amps do have capacitors on the signal path...

Anyway, I'll soon make that capacitor-less buffer for my TVC
I hope it is not too neutral...

Cheers,
M
this gadget is SE , so there is no any xover dist ;

even in case of (almost any) other buffer I know - there is no any xover dist , because they're all A class
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 29th March 2009, 01:17 AM   #1542
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Without being sure, maybe Max refers to alleged capacitor distortions described as ''crossover'' too, maybe you remember the battery bias on caps stuff by JBL etc. In the end, the electrostatically microphonic nature of cap foil following rather high signal voltage as in speakers, seems to stay put by some DC voltage bias IMHO.

JBL paper
  Reply With Quote
Old 29th March 2009, 01:22 AM   #1543
diyAudio Member
 
maxlorenz's Avatar
 
Join Date: Oct 2003
Location: osorno , Chile
Quote:
Without being sure, maybe Max refers...
No. My bad...I wrongly though that dual supplies would make this (even if class A).
Thank you, gentlemen.
  Reply With Quote
Old 29th March 2009, 01:23 AM   #1544
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Page 10 and page 12 for those interested on the whole reference.
  Reply With Quote
Old 29th March 2009, 01:31 AM   #1545
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Default not off topic if put in B1 shebang ;)

Quote:
Originally posted by salas
Page 10 and page 12 for those interested on the whole reference.

that issue mentioned several times over at Audiokarma ,especially in Econowaveguide thread ...

interesting , indeed ...... another toy for grown man (called DiyA)
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 29th March 2009, 01:34 AM   #1546
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
I have done that in speakers, it helps cheaper caps to focus sonically. But you will not find zero crossing distortion. People tried to measure such, could not find. Its the electrostatic thing IMHO. In tight caps it does not much difference in my experience.
  Reply With Quote
Old 29th March 2009, 05:47 AM   #1547
Kinnja is offline Kinnja  United States
diyAudio Member
 
Join Date: Jan 2007
Default capacitorless B1

Quote:
Originally posted by salas
Revised schematic.

Click the image to open in full size.
http://www.diyaudio.com/forums/showt...10#post1591410

A reminder of Salas version since its been mentioned.

Is this still the most recent version?

Would any jfet suitable for the Pass B1 also work here?

I was considering building this before but couldn't figure out what I needed to look for in a relay. Does the 12V refer to Coil Voltage? What does the 700R refer to? I didn't see any similar spec to select for at the suppliers I usually buy from.

Is the npn pair literally *any* npn pair? Or any npn pair that makes sense, at least to someone who understands what they're looking at? And it is a Darlington pair right?

Any comments on parts for this circuit would be appreciated. And thank you Salas of for sharing.
  Reply With Quote
Old 29th March 2009, 08:21 AM   #1548
dejanm is offline dejanm  Austria
diyAudio Member
 
Join Date: Jul 2005
Location: Vienna
This design made by Salas looks really good. I would say it is an improvement to the "original" Pass B1 design for obvious reasons. I wonder only whether for this design a shunt reg after LM317 would bring some further improvements, especially if you omit large input elco, used for filtering ?

For those of you interested in further improving of this simple B1 design, this is a recommended reading:

http://www.borbelyaudio.com/adobe/ae699bor.pdf
  Reply With Quote
Old 29th March 2009, 11:45 AM   #1549
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
I use this for secondary duty, so I did not change it. Of course symmetric shunt regs instead of 317 will bring benefits. But I don't know if it will seem worthy to all people given their dedication and individual system resolution. Its much more costly for time and space or dissipation.

*12V 700R refer to the particular relay coil characteristics (typical to find).

** Any NPN pair means just a couple of NPN transistors. One used as a diode, the other under the relay to pull its coil.

*** 1k and 330R can be lower, say 220R each if no oscillation is manifesting given the particular input and output cabling. That, makes it more dynamic subjectively.

**** I haven't used other than 2SK170BL
  Reply With Quote
Old 30th March 2009, 12:20 AM   #1550
Kinnja is offline Kinnja  United States
diyAudio Member
 
Join Date: Jan 2007
Default Re: capacitorless B1

Quote:
Originally posted by Kinnja

....And it is a Darlington pair right?....
How did I miss that? Definitely not a darlington.
  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
buffer/preamp? TheDriver41 Chip Amps 2 3rd October 2004 09:40 AM


New To Site? Need Help?

All times are GMT. The time now is 04:47 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