Ok, so i want to make an amp out of an old radio case.

[Brian Marshall]

it is a tube radio from the late 60s.

Im hoping that i might be able to use the transformer, and the speaker possibly.

maybe some of the tubes.

anyone recognize any of these tube numbers?

35cs
35w4
12ba6
12be65

Also, if i do replace the speaker anyone know of some good speakers that are under 5 inches?
brian

[Lonestarjohnny]

Great Idea Brian, I wanna see this, i've got an old radio that i've been thinking of building a practice amp out of.
i got a few other project's to finish before i get to this, so I'll keep up with the thread on this. get some good idea's from what your doing.
Johnny

[Fret Wire]

Here's a few I found quick.

http://www.pmillett.addr.com/tubedata/HB-3/Receiving%20Tubes%20Part%202/35W4.PDF

http://www.pmillett.addr.com/tubedata/HB-3/Receiving%20Tubes%20Part%202/12BA6.PDF

http://www.pmillett.addr.com/tubedata/HB-3/Receiving%20Tubes%20Part%201/6BA6.PDF

[Regan]

Are you sure its not 35c5? if it is thats the power tube.
This tube line-up probably doesn't have a power transformer-and is potentially dangerous as a guitar amp. Is there room to add a transformer or two to it?
Regan

[Fret Wire]

http://www.pmillett.addr.com/tubedata/HB-3/Receiving%20Tubes%20Part%202/35C5.PDF

Thanks. You mean this? No wonder I couldn't find data on 35cs.

[Gringo]

Check this thread:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=20178&postdays=0&postorder=asc&start=0

If you have any questions, just shoot

[Hal]

you gotta keep the tube rectifier :-D, just in case you were debating.

[strungout]

Oooo, this is interesting! I have some of the same tubes from an old radio, would be cool if I could do something with em!

This is what I have and the results of my searches:

-50EH5 (power pentode)
-12BE6 (heptode converter)
-12BA6 (RF pentode)
-12AV6 (duo diode-triode)
-50C5A (beam power amp)
-35W4 (half-wave rectifier)

I have mostly no idea what pentodes, heptodes, etc are exactly, but I'm interested.

I have this link that might be of interest:
http://www.nostalgiaair.org/Tubes/ it's a subs database.

I've used the 3 variation of the word interest.

Ciao.

[Brian Marshall]

Are you sure its not 35c5? if it is thats the power tube.
This tube line-up probably doesn't have a power transformer-and is potentially dangerous as a guitar amp. Is there room to add a transformer or two to it?
Regan

Im pretty sure that im just going to rip everything out of it after looking at those data sheets.  Im not ready to "learn" at 300+ volts.  i think ill just buy a kit, or work off of a known design.

There is plenty of room in there though. the case meaures about 10" x 6 x 5.

I may be a couple months before i really get a chance to dig in to it though.

Brian

[Regan]

Yep, thats the tube.
The problem with tubes like this is running them with a transformer, although  you could get a cool little setup going pretty easy with the 35c5 and a 12ax7 using a 48v transformer using a voltage doubler or so for the plate voltage.
I think you would be better off using the chassis(if possible) and picking up tubes that work better together with a power transformer.
Maybe 3 12av6's into a 6aq5 or even a 6ak6? The output transformer would be missmatched then with the stock speaker then.
If you use back to back 12v transformers like in the mctube maybe try a 12fx5-it has an extremely high heater current(450mA) but I have plugged them into a 50c5 circuit without making any bias changes or anything and they sound better.
I'm actually planning out the same thing but using a radio that only has octal sockets, and is around 4"x7"
Regan

[Lonestarjohnny]

Brian, it would make a good candidate for a single ended amp, or maybe you could turn it into the Firefly with a speaker cab added, I think that's what I'm gonna do, I've been aiming to build Doug's amp so maybe i'll make a head version with a speaker cab I'll build myself.
Have fun,
Johnny

[Narcosynthesis]

i think a lot of old valve radios are actually pretty simple to convert to guitar amps, using the same circuitry but with a few mods

the ideal radios should have two transformers in them (this is what i was told anyway, something to do with the voltages in the circuit)

David

[Regan]

The thing is, you NEED to be isolated from the ac coming out of your wall-this is a SAFETY issue. Yes you can convert a radio rather easy, but your skin isn't in the electrical path in a radio like in an amp. Amps built in the same style as a radio with series heaters and no power transformers are commonly called WIDOWMAKER's. Although I have never heard of anyone getting seriously hurt from one of these things, it really doesn't take that much power to do serious damage to yourself, so I don't think its that far fetched a nickname.
Bottom line, there is a reason nobody builds amps like this anymore- its not safe.
Just do yourself a favor and use the parts and chassis, but change over to different tubes and a transformer. The line voltage amps don't sound that great anyway and are prone to noise.
Hope I'm not coming off harsh here, but I have had this beaten into my head over the years and have experimented with line voltage amps(using an isolation transformer) and they pretty much suck. Period.
Regan

[Lonestarjohnny]

your Totally Correct Regan, the Transformerless circuit's are the one's to stay away from, change over to a circuit that has transformers.
Johnny

[smoguzbenjamin]

What you could do is use a low voltage transformer (say 50v) and run the tubes on low voltage. I've heard of tubes running fine at 12v (and I don't mean special 12v tubes) so why not 50v? That should give you some tubey sounds

[Brian Marshall]

well ive put some thought in to it.... and i think im going to build something along the lines of an AX84.... ive never built an amp before.... I figure with the voltages involved.... i'll try a build by the numbers type project first.

I think ill do something based off the ax84 site.

Brian

[Lonestarjohnny]

Sound's good Brian and there is a lot of good info on that site.
Johnny