I am in the planning stage to build a guitar tube amplifier with a spare A-470 audio transformer from a Dynaco ST-70. Does anyone have an opinion on this.
Any advantages or disadvantage using a "Hi-Fi" audio transformer in a guitar amp? The transformer is rated at 35 watts with push-pull EL34's.
Thanks,
Sal
Any advantages or disadvantage using a "Hi-Fi" audio transformer in a guitar amp? The transformer is rated at 35 watts with push-pull EL34's.
Thanks,
Sal
It depends on the sound you're going for. A lot of people (myself included) prefer the sound of the compression (or narrowing of the bandwidth) on a transformer for guitar use. It has a desirable sonic trait (to these ears). Wide bandwidth hi-fi type transformers can be used with no problem what-so-ever, and some amp companies did, but you may not find the sound to your liking.
VTL used Fender bassman transformers in the early days to good effect.
If you have an A470 laying around- try it!
VTL used Fender bassman transformers in the early days to good effect.
If you have an A470 laying around- try it!
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I think a lot of it is going to revolve around your sonic expectations, if you like a clean sound or something similar to the Standell then this might be an excellent choice for you. I would expect it to be a bit lacking on the crunch end of the spectrum, but you know what? - You can always replace it later if you are not totally happy with the sound..
Try both UL and pentode operation and see what you like best with this transformer.
Consider 6L6 and 807 output tubes as well as the EL34.. Making an amp that will work with both the 6L6 and the EL34 should not be much of an issue..
Try both UL and pentode operation and see what you like best with this transformer.
Consider 6L6 and 807 output tubes as well as the EL34.. Making an amp that will work with both the 6L6 and the EL34 should not be much of an issue..
Requirements for bass guitar and Hi-Fi amps are the same, I mean output stage only.
The tranny you have may be used for 100W guitar amp, with twice higher plate voltage and a quad of EL34.
The low 'E' string on a guitar is (I think) 83hz (concert pitch). Tuning it to a 'D' (one step lower) is not uncommon (although somewhat rare in the rock world).
Wire that thing up and let it rip! Part of the fun in building a guitar amp is that it can be disarming and fun to experiment with what's laying around.
Sunn used complete "Dynaco assembled" amps in their early guitar amps. I have a MKIV from one with the same A470 OPT. Later models used the Dynaco circuit on their own chassis. Might want to skip the Ultralinear connection tho, Fender used UL OPTs in some of their 70s models. They are NOT the sought after models.
Craig
Craig
I think that's a matter of taste. I'm a (frustrating) jazz guitar player, so I look for a warm but clean sound, rather than crunchy. I remember playing through one of those late '70s Twin Reverb amps with the pull-out master volume (get rid of it!) and the UL OPT. It was great with a hollowbody jazzbox like Gibson ES-175. But that type of sound would be unpopular on the broad market, as the amp simply refused to go into "Mesa Boogie mode"...
The cool thing about building your own guitar amp is you can tweak it to your heart's content. I especially liked playing with the response of the tone control stack.
TSC
Lots of fun.
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