• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Hi guys. i just got some tubes, and im wondering...

Hi, I just picked up some tubes at a garage sale. I'm wondering if any are suitable for a tube amplifier (im new to this).

here they are:

RCA 12AX7A
Mullard M8137 (I believe this is a military version of the 12AX7)
Westinghouse 6CM5
Phillips E82CC
RCA 6J11
RCA 6D10
Marconi 6X5GT
GE 6J5 (this one is a metal can, what is the difference between that and glass?)

I'm hoping to build a relatively weak stereo pre/power amp, and maybe a small guitar amp as well.


Any help (and schematics:D) would be greatly appreciated. thanks guys :)
 
A good place to start for checking what tubes are is Duncan Amps

RCA 12AX7A -- your basic hi-mu twin triode
Mullard M8137 (I believe this is a military version of the 12AX7) ???
Westinghouse 6CM5 -- Beam pentode aka EL36 could be used as an output tube
Phillips E82CC -- aka 12AU7 low mu twin triode
RCA 6J11 -- twin pentode
RCA 6D10 -- hi mu triple triode
Marconi 6X5GT -- full wave rectifier
GE 6J5 (this one is a metal can, what is the difference between that and glass?) -- medium mu triode

Lots of pre and driver stages that use 12AX7/12AU7, you have a rectifier, now you just need output tubes with a matching OPT.

dave
 

Colt45

Member
2002-02-01 3:40 am
Canada
i just traded these 3:

RCA 6J11 -- twin pentode
RCA 6D10 -- hi mu triple triode
Marconi 6X5GT -- full wave rectifier

for:

another mullard m8137 (i looked into it, and it is a 12AX7)
and i got a matched pair of 6AX3's.

the people just live down the street, so i could probably go and get whatever i need. I couldnt find any output ones that i see all the time, like the 6L6 though.

theyre charging $2 a tube (or $10 for 7) so i figured it was a fair enough deal:)

hopefully i can do something with the 6AX3's. what are some tubes i should be looking for? I might go drop by there again sometime.

also what is the "OPT" (sorry, im a newbie when it comes to tubes.)

Thanks :)
 
Colt45 said:
i just traded these 3:

RCA 6J11 -- twin pentode
RCA 6D10 -- hi mu triple triode
Marconi 6X5GT -- full wave rectifier

for:

another mullard m8137 (i looked into it, and it is a 12AX7)
and i got a matched pair of 6AX3's.


I'd go back and swap the 6AX3s (high voltage diodes -- useful for a small radio transmitter) for the 6X5Gt full wave rectifier -- you need that for your power-supply.

hopefully i can do something with the 6AX3's. what are some tubes i should be looking for? I might go drop by there again sometime.

common output tubes -- 6L6, 6V6, 6BQ5/EL84, EL34, KT88, on & on ...

why don't you go write down what they have, go to duncan amps and cross-ref them

also what is the "OPT" (sorry, im a newbie when it comes to tubes.)

OPT = Output Transformer

dave
 

Colt45

Member
2002-02-01 3:40 am
Canada
ok cool. i went back, and now i have:

(1) 6X5GT
(1) M8137 (checked it out, and it is a 12AX7)
(1) ECC83
(1) 12AX7A
(1) E82CC
(1) 6CM5
(2) 6005 (beam power amplifier)

ouch, just checked up more on the 6005 and its 4.5w 8% distortion but if ran in "push-pull" its 10w @5%

well i should be able to make something now?
 
(1) 6X5GT -- your rectifier
(3) M8137 (checked it out, and it is a 12AX7)= ECC83 =12AX7A
(1) E82CC
(2) 6005 (beam power amplifier)

The 6005 is listed as a 6AQ5 sub so yes away you go...

More than enuff pre-amp, driver, phase splitter tubes.

More then enuff tubes to build a single ended stereo amp (assuming they work).

You will need a power transformer and some ~5k OPTs and some passive parts.

[IMGDEAD]http://www.mif.pg.gda.pl/homepages/frank/short/001/6/6AQ5.gif[/IMGDEAD]

The 6AQ5 is much more common -- go looking for scematics that use it.

dave
 
Colt45 said:
you think it is possible to use the 6CM5 for a mono amp (guitar)?
I saw that it puts out 44w @8%distortion, which would be pretty nice.

So i need an input transformer(duh) and an output transformer?

I don't know where you got the 44W figure... the data shows a 10W maximum anode dissapation so a single tube probably maxes about 5W.

That new in a box mullard might have some good resale on eBay.

And you will need a pr of OPTs for a stereo amp.

dave
 
Since your 6005 will sub for a 6AQ5 it will also go into a schematic that uses a 6V6 which are quite common. For building a guitar amp it would be good to look for an old console that used a single 6V6 or 6BQ5 output tube because the transformers are small and distort easily. If you want to build something a lot better with more power and a reverb etc drop me a line at [email protected] and I can get you a Hammond organ PP 6BQ5 amp with reverb and a speaker as a kit to build your own with. A friend of mine just sold one of these on Ebay and would sell you one for the same price I believe. It will not have tubes but you can buy used ones from him or new Russian ones for not too much. It would take a bit of work but building boxes are easy and you aught to be able to get a sound like a 60s Fender out of it. Thing is the amp is quite heavy and the chassis is probably 18" long. That does give you lots of room to make changes in circuits later as you learn. The reverb driver is not too large and the reverb tank is not heavy. A alnico magnet speaker will come with it(probably a Jensen). If you write me be sure to put tube amp in the heading or it will get deleted as junk. Shipping will be from Dallas,Tx. You should be able to get a schematic off an Organ newsgroup. Another thing you can do is an old Bogen or Stromberg Carlson PA amp and restore it. (from the same guy)The ones used for voice have smaller OPTs that you can saturate. If you just want to punt I have a small SE(single ended) OPT that is kind of fried but might still work and a power transformer I'll give ya for the price of shipping and a couple of $$ for the packing and my time. They were for 6BQ5 and your 6AQ5 will work just fine. Not to scare you but my advice is to start out with some of the old cheap amps that have volume and tone that you play guitar through, spend your money on a good soldering iron, small pliers and clippers, a good set of wire strippers and very important a variac (a variable transformer used to slowly bring up current in capacitors and not ruin them) and a Recieving Tube Manual and very carefully learn how to work on this stuff. Tubes use very high current and you can really zap your *** good. You don't want to make the lights in your neighborhood flicker!!! Also this is very addicting, but my sound systems sound very good. I do have some SS stuff too, but that is just for movies.