Old tube radio, tubes good for guitar amp?

mountainhick

Tele-Meister
Joined
May 2, 2021
Posts
331
Age
64
Location
Rocky Mountains
Any comments appreciated. The info I've found so far, noted. Qty and type in this radio:

1-6U5
1-6H6
2-6F6-G pair power pentodes. Terry at D Labs has used these.
1-6AC7 Radio frequency pentode audio not recommended unless DC filament source
1-6SA7 Heptode, pentagrid converter oscillator mixer
1-6SC7 dual triod in Princeton 5c2
1-6SG7
2-6SJ7 Gibson used as preamp tubes
1-6SK7
1-6SQ7-GT preamp tube used by Gibson (single triode equivalent of 12AX7 ???)

Powering all these is a 5u4-G which is promising regarding the PT being pretty burly I think.
 
Last edited:

NTC

Tele-Afflicted
Joined
Mar 17, 2003
Posts
1,155
6F6's look very interesting to me. I have one to try, as well as it's older version the 42. Slightly less output than a 6V6.

6SQ7 has a gain of 100 like a 12AX7, it may want a slightly different circuit.

6SJ7 is a sharp cutoff pentode - I am curious about using these as preamp tubes as they really aren't very linear. Look at a datasheet and notice how the lines are not evenly spaced as the grid voltage gets lower - they get closer together. Hence the sharp cutoff name.
 

vintagelove

Tele-Meister
Joined
Oct 18, 2014
Posts
453
Location
NY
I've redone a few Octal tube radios, they've turned out really great, especially considering I paid like 30 bucks each for the bones (beautiful head shell, power and output tx). 6SJ7 grid leak bias, into a 6v6. A slightly less breakup, but a slightly more enjoyable tone than the average champ.

PS, use a choke and star grounding, and they're whisper quiet.
 

Joelski144

TDPRI Member
Joined
Apr 18, 2021
Posts
36
Age
56
Location
Ohio
Those tubes, if functioning, are definitely worth a shiny nickel in the antique radio community! I would think the amp would have to be wired to specifically address the tonal and power capabilities of the tubes, and that road's already been pretty extensively travelled. As stated the 5UG4 is a rectifier tube that is commonly used in a lot of amps today, and gives those amps a different characteristic than ss ones. Some even have both, (switchable, but not together, to my knowledge)
 

Len058

Tele-Meister
Joined
Jan 31, 2021
Posts
286
Location
Netherlands
When I started playing I hooked my first electric guitar to the phono input of a Grundig tube radio. It had a special warm sound. If you can build a circuit around the tube, you can use it.
 




Top