Hi-fi amp to guitar amp

[fossilshark]

Ive recently aquired a large amount (enough to stack a pallet in the shop full) of tube radios/other tube technologies. I found a very nice stereo EL34 hi-fi amp. 2 channels 50 watts each. My questions are:
If i wanted to salvage the transformers, specifically the output transformers, what are some things i should be concerned for since its a bit old/intended for Hi-fi use? Are the output transformers different than ones for guitar amps and could it be a problem? Everything is connected and it appears the previous owner repaired it, but id rather make music than listen to it at the moment. The EL34s are wired in push-pull and i am making a diagram of the transformers in/out connections now.

[drew]

That looks like a Dynaco ST70.  They're still quite popular.  You should be able to sell it for good money to a tube audio fan.  It would be a mistake to cannibalize it for guitar amp parts, IMHO.

[eleventeen]

That's a Dynaco Stereo 70, a well know model for which there is a large constellation of users and afficianados. Triode Electronics (and several others) make replacement/upgrade boards which restore or profoundly upgrade the factory performance which was nothing to sneer at. Those go for $250-300 in "found in the garage rusty and untested" condition and $550 rebuilt. Excellent tube amp for stereo systems. If you go to http://triodeelectronics.com/ you'll see they have boards, chassis, virtually any part. Dynaco amps are a semi-fetish item. I wouldn't dismantle it.


You can use the transformers just fine the way they are; those is that particular one are excellent quality....I myself have a Princeton Reverb from which I took a Dyna Mk 4 (Half of that amp, a mono model) many years ago and changed to 6L6 output tubes. Those trannies are probably Ultra-Linear which means they have screen taps for the output tubes. You don't have to use those taps, you can power the screens with resistors in typical fashion and tape off the screen taps.


You'll probably find, if you actually measure things, that those OTs will deliver noticeably better bass response than most stock guitar amp trannies.


I would recommend, however, that you salvage that one LAST or not at all, and start with any mono amps for which you only have one. The iron in 95% of cases will be perfectly fine and you won't be trashing a fairly valuable item.

[fossilshark]

Just did some quick research and your right, IF i dont sell this i would have to make an amp that i would be able to justify selling for $700, and me not being a big name brand i probably cant do. Ill look around for something else, thanks!

[silverfox]

In many respects that already is a guitar Power Amp. Sunn used Dynaco power amp designs in the early amps. As is it should work very well with amp modeling pedals. I've been playing through a version of this amp for several months now and I'm very happy with it. A simple tube preamp would turn it into any number of off the shelf sounds one could desire.

Sunn S100:

silverfox.

[sluckey]

Here's the manual for that ST-70...

     http://www.curcioaudio.com/st7_mnl.pdf

[kagliostro]

Rebuild or Rebuild or, may be ... Rebuild

Franco

[HotBluePlates]

Use it as your ... ummm .... STEREO!