BF862 Preamp - Page 13 - 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 19th January 2010, 10:03 AM   #121
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally Posted by juma View Post
10VA / 48V = 0.2083 A => 100ma draw easily

BTW, I was talking about 24V AC + 9V AC 10VA transformer (post #28 - final preamp's schematic)
100mA easily is not true for a capacitor input filter loading a transformer.
~100mA is the maximum continuous rating from a 10VA 48Vac transformer.
At this current the transformer will be running hot.
It may be hotter than the maximum temperature rating of the manufacturer.

Where do you suggest he buys a 24Vac + 9Vac ~10VA transformer?
__________________
regards Andrew T.
  Reply With Quote
Old 19th January 2010, 11:06 AM   #122
juma is offline juma  Serbia
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Zemun
Quote:
Originally Posted by AndrewT View Post
100mA easily is not true for a capacitor input filter loading a transformer.
~100mA is the maximum continuous rating from a 10VA 48Vac transformer.
At this current the transformer will be running hot.
I run this preamp with two transformers (3.9VA each) and they are absolutely cool. Stop seeding paranoia.

Quote:
Originally Posted by AndrewT View Post
Where do you suggest he buys a 24Vac + 9Vac ~10VA transformer?
I suppose the schematic (post #28) is a suggestion enough.
  Reply With Quote
Old 19th January 2010, 02:05 PM   #123
juma is offline juma  Serbia
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Zemun
To avoid possible misunderstanding, I should be more specific about transformer and PS. The fact is that whenever there is a precise explanation but longer than 5 sentences, there will be someone who didn't read it carefully enough or simple doesn't understand it and we have an instant controversy.

To avoid that, I say:
- readers who understand the schematic and have some knowledge and experience will know what to do;
- the rest of the crew take the 30VA transformer or 50VA or whatever makes you feel good

I made this preamp, it works nicely for me and for guys who built it, I'm sharing the project here - that's all I can do. I can't make anyone learn anything and I can't pet anyone's vanity.
  Reply With Quote
Old 19th January 2010, 03:34 PM   #124
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
Dear juma, don't get tempted everyone is just sharing their thought[s]

i really very appreciate and thanks your hardwork for sharing this and i like it very much... you are one of the man in my admire list
__________________
~.~
  Reply With Quote
Old 19th January 2010, 03:45 PM   #125
njepitt is offline njepitt  United Kingdom
diyAudio Member
 
Join Date: Aug 2008
Location: Maine
juma,

Let me add my thanks for your contributions also. It's much appreciated, even if I am a slow learner...

Cheers

Nigel
  Reply With Quote
Old 19th January 2010, 06:53 PM   #126
npapp is offline npapp  United States
diyAudio Member
 
Join Date: Feb 2006
Location: New Jersey
Schro20, Bappe & Ucciopino, A couple of months back you expressed interest in joining a GB for Juma's pcb. I have had your names saved on a list. The GB is progressing and I am about to the closed the buy. Please confirm if still intend to participate either via PM or by posting to the GB thread. The GB is here http://www.diyaudio.com/forums/group...ml#post2053799
  Reply With Quote
Old 19th January 2010, 07:08 PM   #127
juma is offline juma  Serbia
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Zemun
Hi npapp,
please remove my nick from that GB - I know that you mean it as a recognition, but someone might think that I have some financial interest in that GB which is not the case.
Thank you
  Reply With Quote
Old 19th January 2010, 07:32 PM   #128
npapp is offline npapp  United States
diyAudio Member
 
Join Date: Feb 2006
Location: New Jersey
Quote:
Originally Posted by juma View Post
Hi npapp,
please remove my nick from that GB - I know that you mean it as a recognition, but someone might think that I have some financial interest in that GB which is not the case.
Thank you
Hi Juma, Sorry if my naming made you uneasy. Of course this was only meant for recognition since this was your design. I don't know if there is a way to change the name but maybe one of the moderators can help. I will ask and see how to best resolve this issue. In the meantime, I can clarify that you are not a partner in this group buy. Also, there is no financial gain planned for myself. Any excess funds will go to forum in the form of a donation when the GB is complete.

Nick
  Reply With Quote
Old 19th January 2010, 08:00 PM   #129
Variac is offline Variac  United States
diyAudio Editor
 
Variac's Avatar
 
Join Date: Dec 2001
Location: San Francisco, USA
Quote:
Originally Posted by npapp View Post
Hi Juma, Sorry if my naming made you uneasy. Of course this was only meant for recognition since this was your design. I don't know if there is a way to change the name but maybe one of the moderators can help. I will ask and see how to best resolve this issue. In the meantime, I can clarify that you are not a partner in this group buy. Also, there is no financial gain planned for myself. Any excess funds will go to forum in the form of a donation when the GB is complete.

Nick

Name changed
Mark
  Reply With Quote
Old 27th January 2010, 09:39 PM   #130
njepitt is offline njepitt  United Kingdom
diyAudio Member
 
Join Date: Aug 2008
Location: Maine
Hi Guys,

No-one responded to my post #119 about redoing the output buffer boards, so I decided to go ahead and do it anyhow... Photo attached of the six boards ready to be installed in DIP-16 sockets.

"Six?" you may ask... Don't worry, I haven't suddenly decided to tri-amp the system I only need four for Big Greenie, but making six at the same time is little more work than doing four, and I decided I'd like to have a couple of spares. This way I'm covered if any of them is duff, and if all are OK then either I build another preamp, or some lucky friend gets one...

Each of the boards contains the basic preamp circuit minus decoupling and output caps. (PSU is obviously not on it...)

Next couple of evenings I intend to pull the main board, and replace the larger output buffers, for all the reasons explained in #119. It should also allow for a much cleaner p2p layout on the bottom, which has to be a good thing...

Cheers

Nigel
Attached Images
File Type: jpg IMG_5316.small.jpg (239.4 KB, 756 views)
  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
Tube Preamp Popping on Source Input Change (?) / 6DJ8 Preamp On Chip Amps MartyM Tubes / Valves 3 16th October 2008 04:52 AM
twisted pear Preamp/other suggestions for Preamp kit LukeDuke Chip Amps 1 1st February 2008 09:57 PM
Electret mic preamp - will phono preamp work? darthmullet Analogue Source 6 12th October 2007 07:32 AM
wiring preamp outs on a preamp bonsai171 Solid State 4 22nd March 2004 10:13 PM


New To Site? Need Help?

All times are GMT. The time now is 10:35 AM.


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