4D32 SE amplifier... help! - 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 16th November 2006, 07:40 PM   #1
diyAudio Member
 
fpelleti's Avatar
 
Join Date: May 2005
Location: Quebec
Default 4D32 SE amplifier... help!

Hello people,

I plan to build a 4D32 single ended amplifier soon. I love the way 4D32 tubes look and I found a schematic that should provide a nice 20W output. The schematic is here :

http://members.at.infoseek.co.jp/lag...shido/4d32.png

Could someone help me with the 2SC2335 setup? I understand that the 7 zeners are intended to produce a stabilized 336V to the screen, right? What about the 10Yd2.4 diodes? Are those zeners? Can't find this number anywhere... There a 3 units in parallel? They are used for emiter - base saturation?

Do you see another way to provide stable screen voltage?

Tell me if I'm right...
  Reply With Quote
Old 17th November 2006, 11:10 AM   #2
diyAudio Member
 
Lord Winter's Avatar
 
Join Date: Apr 2006
Location: Zenta
Default No need for panic.

Hello Fpelleti !

Yes, those japanese schematics tend to be confusing sometimes.
However, that sub-circuit is just a simple zener stabilizer with emitter follower. Just replace that "10YD2,4" with 10-15 Kohm 2watt resistor, and you're ready to go !
__________________
- I say let the Lord be our shield!
- The only shield I see is the one coverin' yer eyes.
  Reply With Quote
Old 17th November 2006, 02:23 PM   #3
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Looks like a standard basic vreg circuit.

I'd add the "reverse" protection diodes to that circuit, in case a tube decides to go south... you can find them in the app notes for basic three pin vregs.

Looks like the diodes "X3" are supposed to be three in series, probably to make sure the PIV is high enough.

You could use a resistor, since the purpose of the diode(s) or the resistor is to give the Zener string enough voltage & current to operate.

You can substitue any vreg circuit you like in place of the one they used.

One can make the case that a simple divider with or without a cap multiplier (the same circuit with a cap rather than a zener string), and/or a filter with a choke added is just as good sounding or maybe better sounding?

Another idea is to make a separate diode/filter arrangement off the primary with a choke input and see if that magically provides the necessary (lowered) voltage for the screens?

You might consider changing the drive circuit to be DC coupled, and or find another way to drive the tube in A2 rather than A1...

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 17th November 2006, 03:55 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
I'm pretty sure that the diode shown on the collector of that transistor is just a current source. (current generator) Three of them in series are presumably to assure that the dissipation and voltage ratings of the devices is not exceeded.

I think the zener string is about 340V total. It is something of a brute force approach to supplying the screen. Below I am suggesting something even more brute force, but hopefully a lot more interesting..

You could probably replace that whole circuit with a couple (or 3) gas tube regulators.
0A2 - 150V
0B2 - 106 - 108V
0C2 - 68 - 83V

Strikes me that 3 0B2 in series would put you right in the ballpark. Total bias under quiescent (no signal) conditions should be near 30mA - the maximum rating of the 0B2, and must not fall below 5mA or the tubes will extinguish.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 3rd December 2007, 04:20 PM   #5
Bigmatt is offline Bigmatt  United States
diyAudio Member
 
Join Date: Nov 2007
Default 4D32

Did you make it?

Matt
  Reply With Quote
Old 4th December 2007, 02:38 AM   #6
diyAudio Member
 
fpelleti's Avatar
 
Join Date: May 2005
Location: Quebec
Default 4D32 On hold

Did I made it? Not yet. No attempt yet. To much work outside this summer. I'm working on a EL34 PP right now. The other amp is for next year.
Attached Images
File Type: jpg opus3b.jpg (47.8 KB, 406 views)
  Reply With Quote
Old 4th December 2007, 03:36 AM   #7
diyAudio Member
 
astouffer's Avatar
 
Join Date: Jun 2004
Location: Pittsburgh, crumbling wasteland
Are those giant caps for the B+ or heater filtering?
  Reply With Quote
Old 1st February 2008, 02:58 PM   #8
diyAudio Member
 
fpelleti's Avatar
 
Join Date: May 2005
Location: Quebec
Default giant caps

Quote:
Originally posted by astouffer
Are those giant caps for the B+ or heater filtering?

These are for B+. Two 3500 uf is serial arrangement. Let's say that there isn't any hum in this amp!

Francois
  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
Wanted: DIY amplifier builder with experience. I need a 0.7 ohm stable amplifier Audiophilenoob Swap Meet 34 16th May 2005 11:58 PM
Questions about how to decrease the PASS A-40 amplifier into a class AB amplifier. novtango Pass Labs 2 21st October 2002 01:50 AM


New To Site? Need Help?

All times are GMT. The time now is 12:51 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