B1 Buffer Preamp - Page 53 - 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 24th August 2008, 01:12 AM   #521
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Default Re: Slightly OT, but...

Quote:
Originally posted by coredump

... I've tried this with a QC24 today (basically a pot followed by a 6111WA gain stage), and it seems to work in that context, too. The slight midrange dip, that the pot introduced, went, and a touch of harshness with it. I used two 1M Dale CFM55s in parallel for each channel, the pot is a 47K black Alps (allegedly NOS, but I'm not sure about that).

Excellent hint, thanks Salas.

Best,
Oliver
You are welcome. Your pot is actually NOS, had the nickname ''Black Beauty'' and it is chunky. I use one in a tube project of mine. Very good with reliability and tone.
  Reply With Quote
Old 26th August 2008, 04:14 AM   #522
rgheck is offline rgheck  United States
diyAudio Member
 
Join Date: Aug 2003
Location: Canton MA
I'm thinking of making two of these, basically, and using them as a balanced buffer. I could really use such a thing.

Any particular thoughts on this idea? Are there particular sorts of matching about which I should be careful?
  Reply With Quote
Old 26th August 2008, 12:11 PM   #523
udailey is offline udailey  United States
diyAudio Member
 
Join Date: Mar 2008
You need to match Q100 and Q101 and then Q200 and Q201. But thats it. The big caps can be between 1000uf and 15,000uf or maybe more. Nelson likes to use the Dale RN55 resistors and all resistors are 1/4 watt except R1 which is 3W.
http://search.digikey.com/scripts/Dk...;keywords=rn55
Thats for the Dale resistors
http://www.tech-diy.com/Store/SmallSignal.htm
Thats for the matched 2SK170. Remember you dont need the matched quads just 2 matched pairs.

Uriah
  Reply With Quote
Old 27th August 2008, 12:43 AM   #524
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Salas,

Thanks for posting your schematics. I'm going to build this unit as soon as I get my JFET's from Luvdunhill's group buy.


Question for those who like an external psu arrangement.
I know I can either place it in the box or locate it externally. I'm leaning towards putting the psu in a separate box. If I do so, will I need to place some decoupling caps on the rails of the B1 circuitry to keep everything nice and clean sounding?
  Reply With Quote
Old 27th August 2008, 01:23 AM   #525
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
You are welcome. No big deal really... Did it to share some impressions and to check if an even cheaper, straighter approach could be an option for all. Its a hobby to me, hobby is supposed to be fun. Good luck with your build. Its a very rewarding top value project and it will serve you well. We all must thank Nelson Pass for bringing forward such great and easy stuff to the DIYers. A real gentleman and a guru. Remember that him and John Curl actually invented top audio solid state engineering in the 70s.

If you put the transformer, bridge, and main filter capacitors in a separate box, keep the regs next to the main circuit,and just use 100nF poly caps across LM317 & 337 inputs to ground.
  Reply With Quote
Old 27th August 2008, 03:36 AM   #526
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Salas,

I know this project will bring me much enjoyment. I built a BUF03 preamp in the early 90s and I think it's time for an update.

I've been reading but not posting much until now and I appreciate the sharing of knowledge from Nelson Pass and John Curl. I feel like I've hit the mother lode.

I'll follow up with my impressions of the B1 once I'm done. I just have to wait for those JFETs to arrive...probably October...sigh
  Reply With Quote
Old 27th August 2008, 07:31 AM   #527
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Maybe you can make it with 2N5459 until the 2SKs arrive? It will work. And would be interesting for sonic differences report.
  Reply With Quote
Old 27th August 2008, 03:38 PM   #528
sonidos is offline sonidos  United States
Libertador de la Música
diyAudio Member
 
sonidos's Avatar
 
Join Date: Jul 2007
Location: Round Rock, TX
Salas,

I will certainly give it a try with the 2N5459. Thanks.

I've got a few parts to buy, but it shouldn't take me long to do a p2p version. Fortuntately, I have a spare xformer and populated psu board handy.
  Reply With Quote
Old 29th August 2008, 11:43 AM   #529
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Default Cheap & Cute

Here it is fully boxed. Ready to interface reliably and neutrally whatever source.

Click the image to open in full size.
  Reply With Quote
Old 29th August 2008, 12:22 PM   #530
diyAudio Member
 
Join Date: Dec 2006
salas, nice looking! It fits the supposed "house-doctor" mode in it´s tecno/medical style. Just to bring it with you to different healthy power amps for testing


A Buffer question from a total nonelectric: Those 1M Resistors in the Input 100;101, 200; 201 (exactly after every single input) can´t I put just one in front of the Pot?
greets
stefan
  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 08:40 AM


New To Site? Need Help?

All times are GMT. The time now is 10:23 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