7068 power tubes?

[Yoda-Ace]

I picked up an old USA made guitar amp (sound). It has 2x 7068 power tubes. I would like to convert it to a more common type (6v6, el84, 6l6). I want to use the transformers that are in it. Which power tube would be the closest match. The 7068's have the skinny pins in big tube. Do 7068's have any redeeming value? Thanks

[skyboltone]

I find no 7068 tube in my receiving tube manual or in either of the online references I use. 7058?

I have a transmitting tube manual in storage. I might be able to get over there sometime soon. I'll check.

Dan

[krash]

you sure that's not a 7868?

if so that's approximately a noval version of a 7591A and in which case, you can get new 7591A's from a couple of sources (they are octal), or you can substitute a 6L6 approximately for a 7591A (you lose some volume).

[tictac]

7868's and 7591's Rock! They are the size of a 6V6 but with the power of a 6L6GB and they sound fantastic both for Hifi and Guitar amps. Ampeg was one of the few companies that was wise to these tube which were developed specifically for audio.

Just finished an amp using these tubes and I'm very pleased. Right now these are my fav power tube.

TT

[tictac]

Uh, you do mean 7868 and not 7068 right? The 7068 is called a grid leak detector tube. I've never seen one in a guitar amp.

The 7868 has a noval base (big tube with 9 pins) The octal base equivelent is the 7591.

Pull thte tube out and look at the pins. If it has 9 pins its a 7868 if it has 4 pins its a 7068.

[Yoda-Ace]

The tubes have 9 pins. The tubes themselves have the printing partially worn off. The chassis has 7068 written on it in pencil. I guess the previous owner tried to write the names on the chassis and messed up. The amp is named Sound. It has 4- 12ax7s , 1-12au7, and 2-7868. It has trem, and reverb controls, but no reverb tank.

Thanks for the clarification! I didn't realize the 7868 was a cool tube. Would you just leave the amp as is, rather than convert it to a more common type of output tube? It does have good tone.
Thanks

[skyboltone]

Thanks for the clarification! I didn't realize the 7868 was a cool tube. Would you just leave the amp as is, rather than convert it to a more common type of output tube? It does have good tone.
Thanks

Sure, so long as you can get the 7868 tubes. All of the more common guitar amp tubes are very expensive in New Old Stock. This one might be a sleeper and give you great performance for cheap. I would however start accumulating the lifetime supply by contacting the various suppliers and buying a few pair.

Dan

[rfgordon]

Here's some data on the 7868.

This is a link to data sheet on the tube:

http://www.mif.pg.gda.pl/homepages/fran ... 7/7868.pdf

[philmanatee]

I have a Magnatone with 7868's, it's one of my favorite amps. Phil

[tictac]

You could install octal sockets and rewire them for 7591's. JJ's makes a 7591 for a reasonable price; the Old Stock 7868's and 7591's are obscenely expensive nowdays...

You might also check JJ's website to see if they're making the 7868 as well, if so get yourself a supply of them, you really don't want to be buying NOS tubes for this amp unless your independently wealthy...

TT

[philmanatee]

I got lucky and found a local guy with a repair shop that sold me a bunch for cheap. Now if I could just find a stock of NOS 7027A's for my Oliver! Phil

[Yoda-Ace]

Thanks for the links and tips. Now I know what I am dealing with. It wouldn't be a gigging amp for me, but now I definitely want to see what it will do.