12B4 Preamp - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 4th February 2009, 08:30 PM   #11
diyAudio Member
 
raypalmer's Avatar
 
Join Date: Dec 2008
Location: Burlington
also.. please don't laugh at me.

but what's that two circles symbol just beneath B+ denote??
__________________
Wherever you go there you are.
  Reply With Quote
Old 4th February 2009, 08:37 PM   #12
diyAudio Member
 
philipbarrett's Avatar
 
Join Date: Feb 2005
Location: Dallas, Texas
Send a message via AIM to philipbarrett
You asked the question I was too scared to! I looked through every reference I had but couldn't find it.
  Reply With Quote
Old 4th February 2009, 08:49 PM   #13
diyAudio Member
 
Join Date: Feb 2005
Location: leeuwarden, netherlands
the symbol represents a current source
__________________
emission over emittor
  Reply With Quote
Old 4th February 2009, 08:49 PM   #14
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
It is a constant current source or CCS. A quick search will bring up more information than you could ever want.
  Reply With Quote
Old 4th February 2009, 08:55 PM   #15
diyAudio Member
 
raypalmer's Avatar
 
Join Date: Dec 2008
Location: Burlington
Ok. This is so simple I'm going to make it.

Questions though... 47nF... how many uF is that? What kind of cap?

The Resistors, what voltage should they be good for where not indicated?

The xformer... how many volts at how many amps on the 120VAC and 12VAC secs?

Sorry I'm a bit thick when it comes to this stuff.
__________________
Wherever you go there you are.
  Reply With Quote
Old 4th February 2009, 09:05 PM   #16
Tweeker is offline Tweeker  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Cincinnati, Ohio
nF=nanoFarard, μF=microFarad. So 47nF is .047μF.
__________________
Be sure your foil hat has a good low impedance ground.
  Reply With Quote
Old 4th February 2009, 09:06 PM   #17
diyAudio Member
 
raypalmer's Avatar
 
Join Date: Dec 2008
Location: Burlington
Thanks tweeker...
__________________
Wherever you go there you are.
  Reply With Quote
Old 4th February 2009, 09:11 PM   #18
Tweeker is offline Tweeker  United States
diyAudio Member
 
Join Date: Dec 2004
Location: Cincinnati, Ohio
No resistor will see more than 200V in that amplifier, wattage is the only rating of concern here.
__________________
Be sure your foil hat has a good low impedance ground.
  Reply With Quote
Old 5th February 2009, 12:34 AM   #19
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
The inexpensive O/P coupling cap. setup is a 5 μF. GE 40L3501 MPP bypassed by a 470 nF. film and foil part. 470 nF. = 0.47 μF.

Jim McShane has the GE MPPs and some of the now NOS Panasonic ECQ-P(U)s. Other candidates for the film and foil bypass are a Dayton from Parts Express and a 716P series Orange Drop.

The diodes in the B+ bridge are 600 PIV Schottkys. Church mice are noisier.
__________________
Eli D.
  Reply With Quote
Old 5th February 2009, 02:33 AM   #20
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
Quote:
Originally posted by Eli Duttman
film and foil ... Dayton from Parts Express
Besides the fact that these sound terrible, I've had them fail as a dead short at reasonably low voltages. For a cheap cap, go with the 716.
  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
Troubleshooting hum in 12b4 preamp.. finally almost done!! 240z4u Tubes / Valves 60 29th October 2010 08:01 PM
WTB: 12B4 Tubed Preamp. Zekk Swap Meet 0 18th March 2009 04:17 PM
12B4 Battery Bias from (Preamp: Foreplay or 5687 or 12B4 ) DougL Tubes / Valves 3 2nd August 2004 07:06 PM


New To Site? Need Help?

All times are GMT. The time now is 03:08 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