home made tube amp with 12v b+ how to build one? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 19th September 2010, 05:13 PM   #1
bichela is offline bichela  United States
diyAudio Member
bichela's Avatar
Join Date: Aug 2010
Location: Winsted, Connecticut, USA
Default home made tube amp with 12v b+ how to build one?

I saw on youtube a design for a AM radio reciever that uses a 12AU7 with a B+ of 12vdc. now can one build a small submini amp that uses sub-mini tubes with a b+ of 12vdc to drive a transisistor radio speaker? Any one got a schematic? I want to learn to build tube stuff in little easy steps.

such a teeny amp could be a conversation piece in its own right. also is a subminiture tube the same as a nuvastore tube? The ones I know of have long wire leads instead of pins on their base.

I do have a 12AX7 tube laying around. just got to get a socket for it. its minituare (obviously) but not a subminiture tube. Whats the subminiture version of this tube? I would love to combine this with that radio reciever I mentioned above. and make a nice little AM radio portable.
  Reply With Quote
Old 19th September 2010, 05:27 PM   #2
diyAudio Member
Join Date: Oct 2004
Location: Maui, Hawai'i, USA
See if you can find circuits for mobile aps from before sand days. Car radios all operated on 12V (actually, probably mostly 6V) and did pretty well. I would expect that they used some special hi-Z speakers, but maybe not.


  Reply With Quote
Old 19th September 2010, 05:38 PM   #3
Arnulf is offline Arnulf  Europe
diyAudio Member
Join Date: Feb 2009
Your "amplifier" is going to put out miniscule amount of power, far less than the input that is likely to be driving it (MP3 player or something like that).
mod verb, transitive /mod/ to state that one is utterly clueless about the operation of device to be "modded" and into "fixing" things that are not broken; "My new amplifier sounds great so I want to mod it."
  Reply With Quote
Old 19th September 2010, 06:02 PM   #4
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Google tube AM car radio, there was a whole family of 12V space charge tubes for this application. Note that most of these radios will have a transformer driven, transformer coupled power transistor for the audio output stage. Will not find a tube capable of really doing this job at such a low voltage. (Before space charge tubes car radios had electro-mechanical vibrators and high voltage supplies using step up transformers, and used common tubes from the 6.3V or 12.6V filament families depending on the vehicle electrical system voltage.)

Note that most subminiature tubes were not designed for such low voltage operation although the 6088 and 6418 DHP and others start to work quite well at supply voltages well below 100V. (6GM7 as well, but getting rare and expensive as it's good for headphone amps at 24V..)
"Extraordinary claims require extraordinary evidence." - Carl Sagan

Last edited by kevinkr; 19th September 2010 at 06:05 PM.
  Reply With Quote
Old 19th September 2010, 06:23 PM   #5
taj is offline taj  Canada
diyAudio Member
taj's Avatar
Join Date: Feb 2005
Yeah, I seem to remember car radios just converted the battery DC to AC with a vibrator, then boosted it up to normal B+ values with a step-up transformer, and the rest was just normal (albeit tightly cramped).

  Reply With Quote
Old 19th September 2010, 08:34 PM   #6
diyAudio Member
Join Date: Jun 2004
Location: Indiana
Space Charge and Other Low-Voltage Tubes
If We The People refuse to hear the truth we will be ruled by liars.
  Reply With Quote
Old 20th September 2010, 03:13 AM   #7
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Originally Posted by mashaffer View Post
Thanks for posting, quite an interesting site, and the ones it links to, in particular the Lamphouse Hiker radios..
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 20th September 2010, 04:52 AM   #8
diyAudio Member
Wavebourn's Avatar
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
A very serious military receiver Collins R392/URR used ordinary tubes (well, some of them were special versions of ordinaty tubes with 27V filament) powered by 27 Volt only. In audio output stage it used special double triode. But it was a receiver, not a hi-fi audio amplifier! Transistors on such voltages work much better and are much cleaner than tubes, even such good special tubes like 4P1L for example are.
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 20th September 2010, 05:54 AM   #9
soro is offline soro  Taiwan
diyAudio Member
Join Date: Jul 2010
Location: Taipei
Send a message via MSN to soro
maybe you can try this one.
IT can ues 12AX7 or 12AU7 6DJ8 6922...
Attached Images
File Type: jpg headphone-amp.jpg (33.8 KB, 220 views)
File Type: jpg DSCN4265-1.JPG (123.6 KB, 223 views)
File Type: jpg DSCN4230-1.JPG (120.4 KB, 213 views)
  Reply With Quote
Old 20th September 2010, 06:48 AM   #10
diyAudio Member
Join Date: Sep 2010
Location: Melbourne
I used to have a 32V B+ mantle radio, which used standard miniature valves, the high plate impedance of Valves does not lend itself to low voltage operation, car radios and military field radios used vibrator based power supplies with normal 250 or 300V B+ You probably could make a small mosfet based voltage multiplier to get 32 to 60V B+, don't much power output though.
  Reply With Quote


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
50 Hz in home made power amp zoubour Solid State 13 7th January 2011 07:06 AM
Convert a home amp (110v) to car amp (12v) jimmyvstc Car Audio 4 12th February 2009 05:16 AM
Home made SE 300B amp JosM Tubes / Valves 12 6th August 2008 05:33 PM
Driver for home made bass amp punkrokr1701 Multi-Way 2 27th December 2006 04:09 AM
Home-Made Tube Guitar Heads J.H.R Instruments and Amps 2 14th July 2006 04:30 AM

New To Site? Need Help?

All times are GMT. The time now is 09:36 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2