Champ 5f1 for bass

[fossilshark]

Would a champ 5f1 sound good with a bass guitar (connected to a bass cab of course) or should i go with a different design. My little sister wants to learn bass so i just want to build her a little bedroom blaster, i imagine i would need more power than a 5f1?

[John]

If I were giving it a shot, and wanted a SE amp I'd go with a beefier PT/OT, and run a 6L6 for the power tube. Your heftier OT iron *should* give you better low response.


In the preamp, try a 12ay7 instead of the X, and then use higher plate and cathode resistors. I only say this because the Ampeg I copied did that with 6SL7s, which are fairly comparable to the 12AY7s gain-wise. If you really want sweetness just go ahead and use a 6SL7 

[kagliostro]

Some time ago I've find this on the web





if you want more power swap the power tube to 6L6 or use a pair of paralleled 6V6

obviously PT and OT must be adequate to the power

Franco

[PRR]

I don't see a lot wrong with a Champ with a large OT, perhaps a Hi-Fi OT if you can find 7K (5K is a less-good match). There is adequate bass in the Champ, as much as a bedroom-size speaker needs.

Speaker is perhaps more critical than amp.

5 Watts is pathetic bass POWER (we like 100W-1,000W) but probably all she can get away with in a bedroom.

Actually, unless she is already skilled (how?), _I_ would go through the pile at the pawn-shop and the new-amp shop's trade-ins, get a pre-owned little 20W SS amp with a not-too-sucky speaker. Basic, simple, quick. "Flavor" can wait until she can run her riffs smoothly. (And if she discovers boys, or cars, meanwhile, no big loss.)

[Tony Bones]

My experience with bass amps is that they pretty much must have a stiff power supply and at least a little NFB. And a good OT and speaker as others have said.

Having said that, sure, why not 5F1. But maybe consider running higher B+ and look at the BF Champ for ideas about NFB. Maybe just consider the BF Champ instead of the 5F1... with a good OT and a 6L6. 

[kagliostro]

The idea of something from a pawn-shop is good

but I can understand a father that want to do something with his hands for his daughter

it is all a different satisfaction

Think around this choice, remember what PRR say and decide about what to do

(And if she discovers boys, or cars, meanwhile, no big loss.)

Franco

[fossilshark]

Thanks for all the input. Ma doesnt want me spending money on (another) amp build if we dont know if shell like it, got her a cheap ss amp instead. Really just wanted a reason to build a champ 

[pompeiisneaks]

here's your reason

It's a hell of a lot of fun :)

~Phil

[John]

Reasons are over rated!!

[kagliostro]

 

[Cree]

Building a amp for your sister, PRICELESS. Then when she finds other things that take her interest. It's yours to mod.

[sluckey]

Building a amp for your sister, PRICELESS. Then when she finds other things that take her interest. It's yours to mod.

Aint his daughter. It's his little sister. Big difference.

[PRR]

> consider running higher B+

In a class-A amp (all SE and self-bias push-pull generally), higher B+ will just burn-up the tube. (Unless it was under-run to begin with.) The limit is plate dissipation, not Volts. More volts forces less current and same-power for all practical purpose.

There are extreme cases. Most "audio" power pentodes can't do their best below 250V. If extreme plate voltages are allowed and you can find the "optimum" OT impedance, there may be a few percent more test-bench power (probably not significant in loudspeaker work).

I do favor the NFB on the AA-Champ generally and for bass.

I would not do it for my sister if she were just beginning to play. Students generally should use a rental violin or grandmother's piano until they get well along in their lessons. Not a bad instrument, but they should "earn" a good instrument. The right student will make music on a Sears-Roebucks violin, then get a better fiddle.

[fossilshark]

Got her a cheap crate practice amp, eventually ill make her a 8x15 cab and 1000w 6 channel full tube (rewire mains to 440v in her studio) +triple reverb with 6 rectifier tubes.  in reality i dont really care as long as she doesnt play no communist modeling amps (although they are getting better, probably wont beat tube in my lifetime)