Tube pre + solid state power amp...

[ER]

Is anyone doing this or tried it in the past? With the clean & stiff power section on the dumbles it seems like it wouldn't be too bad a way to go?

Also would an ODS type of pre-amp work for bass guitar? Which one? I was thinking along the lines of something #124ish.

The reason I ask is because I bought a Peavey TB Raxx pre with 2 12ax7's and a 2x130 watt (into 4 ohm) peavey stereo power amp to use as a bi-amp bass amp (2x10 top and 1-15 bottom) for $90 on craigslist and thought why not try and use it for a stereo guitar rig also by gutting and rebuilding the pre...

Easy enough to do , but worth it?

Thanks, ER

[guitardude57]

Bass amps typically are designed for maximum clean headroom.
Sure, there are designs out there that allow for some overdrive as a tonal variation.........the ODS is really about overdrive tone to me. Even though the cleans are nice too.

I suppose you could do the frontend into about anything, since the tone and drive of the ODS, is preamp oriented. But overall, it is better to use all glass in a ODS IMO, for the whole tone package.

It would take some serious tweaking in the tone control components to make it Bass guitar frequency friendly. Possibly a more Fender-like tone circuit would be better for Bass.

For Bass, I would just build the Alembic F2-B Bass pre and adjust some values to your personal taste........... after you build it stock first. Fender Bassman 100 preamp design for the most part I believe.

These are pretty easy to build, and voiced for Bass.
Schemos and build info is around and pretty easy to find.

Works well as a guitar pre as well. Ask Dave Gilmour.

[Structo]

Many times people have played six string guitar through bass amps.
Look at the venerable Fender Bassman prized for it's tone on guitar.

Usually it's OK depending on the amp at hand.

But the other way around, eg bass through a guitar amp, not so good.
The speakers are not made for the long excursion that the bass frequencies produce.

Many guys here have taken amps and converted them to Dumble amps.
Depending on the power transformer and output transformer it can be done.
I'd make sure that the PT is up to the task current wise.
The OT can be used or replaced depending on the original specs.
If it is not possible to use the existing transformers, I would either look for another donor with suitable transformers or just order new transformer.

Also check out the chassis carefully to see if it will work for the amp you want to build.
The head cab may or may not work for your needs as well.

There have been amps that used SS output in the past.

Pritchard comes to mind, Earth amps, some bass amps as well.

[ER]

The only tranny is the pre power tranny which is already supporting 2-12ax7's so it would be basically turning the pre into something more dumblesque. For guitar I would use different speaker cabs than for bass.

I have a couple friends, one who used to, and one who still does work at alembic, and I was thinking something along the lines of an alembic/showman type clean stage with some 124 flavoring, with an OD section. Right now the peavey has a fenderesque clean stage (pre gain) with passive EQ followed by a post gain volume stage and active EQ, plus bright and boost and shift switches. All stages are 100k/1.5K 22uF so possibly just tweak it a little and add a little more control over gain in and out of each stage?

It already sounds pretty dang good for guitar into a 4x12, very ballsy and powerfull, just wondering if I can improve the OD from the barky marshall hair metal tone it gets now. The old peavey rack bass pre is 99% the same as their guitar pre.

Here's a schematic;
http://www.steamingaudio.myzen.co.uk/do ... ircuit.pdf

I'll give it a go, could always go back, or put together a tube power amp down the road if the SS amp doesn't sound good for guitar. Just trying to get double duty out of the thing (cheap fun).

-ER[/url]

[Structo]

Yeah, bass preamps are usually designed for clean tone.
As well as the power amp.
Big watts and clean power.

Still not real sure what you are trying to do but it may be the drugs I'm on.

[ER]

Sorry I was pretty unclear in the previous posts, I'm talking about a single space rack mount tube pre-amp that uses 2 12ax7's.

I got it to use as a bass rig, but I'm not really a bass player, just something to have for when people come over to jam or the occasional recording. It was cheap at $40 and I thought if a pheonix style ODS pre amp would would work O.K. for a standard 4 string bass, then I may be able to use it for guitar and get more use from it instead of having another amp sitting around only used for occasional bass duty.

It sounds like a good clean section would work for bass and just use the OD when using it for guitar.

Since no one seems to have experience with this I'll just try it and post the results. Maybe if I build a dumble that's more like a bass amp I'll end up sounding just like stevie ray...

-ER

[M Fowler]

Well in that case your looking for something like this but in a bass format.

[Structo]

Did you build that Mark?

[M Fowler]

No I built a single tube preamp.

I can't find the final wiring photo right now, it has a hum I need to sort out.

Mark

[Structo]

Well there is your problem right there!
No wires!

J/K

Looks nice.

[markusw]

Also would an ODS type of pre-amp work for bass guitar?

Thanks, ER

FWIW, I really like how my 5-string bass sounds through the clean channel of my 50W Non-HRM (100k/1k5/10µ cleans) with an 80s stack plus deep switch (with an 15" cab of an ampeg combo). Bottom end definitely is not an issue
Never tested it at gig levels though....

[Structo]

Yes, I also play a 5 string through my amp when I am just jamming to a loop I recorded.
But, at low volume.
The EVM's seem to handle the bass pretty easily but I don't want to damage them so I keep it low.

[guitardude57]

Tom,
I wouldn't worry too much about playing bass through EVM's. Even 10 inchers can handle it. If the box is tuned for it, will sound good too.

[Grant]

I always loved Jerry Garcia's tone and that's what he did...

Fender Twin Pre >
McIntosh MC 2300 Power Amp