NOOB ALERT! sooo omany questions..... - 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 7th April 2013, 09:15 PM   #1
diyAudio Member
 
Join Date: Apr 2013
Default NOOB ALERT! sooo omany questions.....

Hi everyone!

I recently came across a cache of old vacuum tubes. Most look used.. A few are in boxes. I have a feeling that most of them are from televisions and old home audio stuff. I have been able to identify a few of them. ( I have a '69 Bandmaster Reverb) But.. danged if I know if any of them are working .. I was wondering if perhaps there may be a member ( with a tester) close to the Sacramento area who might be willing to meet with me and give me a hand finding out if any of these things are working and worth anything for say a .. few choice tubes or a 12 pk or somethin?? I have pictures I can upload to photobucket if that would help

Thanks,
Ben ( Davis CA)
  Reply With Quote
Old 8th April 2013, 12:47 AM   #2
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
You might sell them as-is.

Put up a list...If the tubes are not wanted then you don't need to use your time to test them.

Just a suggestion.

__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 8th April 2013, 10:07 PM   #3
diyAudio Member
 
funk1980's Avatar
 
Join Date: Sep 2011
Location: Groningen
That's just one question...
  Reply With Quote
Old 18th April 2013, 04:07 AM   #4
diyAudio Member
 
Join Date: Apr 2013
rightyo! Funk1980! The other question is what happens if I pop a 12BH7A into a spot on my 1969 Fender BandMaster Reverb that is supposed to have a 12AT7 in it?
  Reply With Quote
Old 18th April 2013, 06:29 AM   #5
diyAudio Member
 
Join Date: Oct 2004
Location: Adelaide South Oz
Putting a 12BH7A in place of a 12AT7 in fact would not be too serious, more by luck than anything else. In this particular case the pin outs match, same heater wiring etc. but just stuffing any tube in any tube socket just because it fits is "fraught".

The 12BH7A however would not run at the operating point expected by the Bandmaster. And would probably sound pretty awful.

Cheers,
Ian
  Reply With Quote
Old 18th April 2013, 06:34 AM   #6
diyAudio Member
 
Join Date: Apr 2013
WEEEEEELLLLLLLLLLL.. I did it.. turns out.. sounds freaking awesome! its a much darker tone.. I dont get the distortion at high volumes but other than that its pretty freaking sweet! It wasnt just any old tube really.. a dual triode instead of a twin triode. right?
  Reply With Quote
Old 18th April 2013, 11:29 AM   #7
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Dual triode = twin triode. Two names, same thing.

If swapping a valve for a quite different valve (which happens to have the same pinout) 'improves' the sound then either the circuit was badly designed for the first valve or the listener prefers the distortion introduced by the second valve. You choose.
  Reply With Quote
Old 18th April 2013, 01:24 PM   #8
godfrey is online now godfrey  South Africa
diyAudio Member
 
Join Date: Nov 2009
Location: Cape Town
Dude, it's a guitar amp! They're supposed to be "badly designed". You think musicians want low distortion?
  Reply With Quote
Old 18th April 2013, 01:47 PM   #9
diyAudio Member
 
funk1980's Avatar
 
Join Date: Sep 2011
Location: Groningen
Not to mention the 12BH7 draws twice the heater current from the PSU compared tot the 12AT7. Are you sure it's up to it?
  Reply With Quote
Old 18th April 2013, 02:24 PM   #10
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
Join Date: Dec 2012
Location: SF Bay Area
Oddly [DF96] enough ... a musician friend had a similar experience, except with the 12BZ7 tube, again pinout-compatible with the venerable AX7. He asked "is this OK to do?", and taking a look at his amp, I confirmed it had a stout heater, and the usual resistor-capacitor bypass on the front end, so it was a go.

And the sound definitely got "darker", less distorted at the top (which for guitar players is a bug, not a feature, mostly), but in the middle region, was darn sweet. Very jazzy. So... some 5 years later, the 12BZ7 has been replaced ceremonially to show people, but it remains in the box for the gigs.

As to double-the-heater-current, we're not talking about serious current: the overall power draw (line tubes, phase inverter, push-pull 4-tube final) might increase 5%, maybe less. Clearly within design spec.

I highly recommend experimenting with these "front end tubes" in guitar amps. Just be sure that the whole amp is tube based, and not one of the dumb modern ones with a single 12ax7 (typically behind a cute orange LED backlit or underlit window!) in the front end, and all silicon after that. The double-amp heaters might well be way beyond that capacity of the design! Only ALL TUBE is safe.

12AU7, 12AT7, 12AY7, 12BH7, 12BZ7 ... all good, different gain! Its especially fun to try different manufacturers' substitutes - comparing the Ruskies to the Chinee, to the German's NOS (since the make them no more). The front-end tube of the guitar amplifier has one of the most significant roles in "sound shaping" of any of the tubes.

Have fun!

Also check out the "franks tube pages" sites. It is NOT easy to find all the substitutes, but with some scanning and a pad of paper, you will locate 50 or so different types to give you stuff to try.

GoatGuy
  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
Noob alert! Adcom 565 Q's gt4rcdude Solid State 9 22nd December 2008 09:50 PM
Noob with questions... Tristanc1 Chip Amps 6 23rd September 2006 10:17 PM
Noob Questions... MrGeebs Solid State 7 24th March 2006 03:17 AM
Remedial Pearl Phono Questions - NOOB Alert hatfield Pass Labs 1 24th May 2004 05:01 PM


New To Site? Need Help?

All times are GMT. The time now is 05:56 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