Bass/guitar tube preamp with small power stage

[tinitus]

Originally Posted by Fredde79

I don't know anything about the ecc99.....What would be the benefits of using the ecc99?

very tough preamp/driver tube

google ecc99 mini amp (its on DIYstompboxes)

might be possible to make it stronger and better

and patiently waiting to see what the ManicMidget is about

Fred Nachbaur's Vacuum Tube Projects

[Fredde79]

Originally Posted by tinitus

very tough preamp/driver tube

google ecc99 mini amp (its on DIYstompboxes)

might be possible to make it stronger and better

and patiently waiting to see what the ManicMidget is about

Fred Nachbaur's Vacuum Tube Projects

Ok thanks! Im only wondering if it's necessary since I'll only need line level output, and the only important thing is to match the power tube with the OT. Im not sure how the ecc99 is compared to a 12AU7 soundwise, but if they're roughly the same, a 12AU7 should work equally well (but maybe with a smaller OT).

Also, the ecc99 is physically bigger and I'm planning to fit everything into a 2U rack housing.

[tinitus]

Originally Posted by Fredde79

Well, this is intended as a bass preamp.

just thinking out loud ...but since you study guitar amps to get inspiration, may be important to consider that they could be designed for overdrive guitar sound....and you may not need that for bass

whatever, I kind of liked your first idea/schematic

don't know why, but I find this site... 'toxicating'

LONE WOLF BLUES COMPANY

Originally Posted by Fredde79

Sorry if I was unclear, what I meant was to replace the single ended 6L6 stage in the schematic with a push pull 12AU7 stage.

Like Doug Hammonds FireFly:

you mean only the output stage ?

heck, sometimes there is simply just too much stuff and ideas to try....

[Fredde79]

Originally Posted by tinitus

just thinking out loud ...but since you study guitar amps to get inspiration, may be important to consider that they could be designed for overdrive guitar sound....and you may not need that for bass

whatever, I kind of liked your first idea/schematic

don't know why, but I find this site... 'toxicating'

LONE WOLF BLUES COMPANY

Yes, I've thought a lot about that and it's much easier to find schematics for guitar. The idea is to get a clean sound but with the possibility for a *slight* overdrive when pushed. I guess I'll just have to experiment.

One important thing is to get the right B+ voltage for appropriate headroom, but that can be fixed pretty easily by changing the RC-resistors in the PSU. Cathode resistors and capacitors are also easy to change. The difficulty, as I see it, is to get the right output transformer on the first try, since these cost money. I see that the ecc99 mini amp you mentioned uses a Hammond 125B which is 5W, so maybe the 3W version would be enough with 12AU7 as power tubes.

But: I've read that an OT will saturate easier at low frequencies, so I might need a bigger one for bass. I'm not sure about this one though.

[Fredde79]

This is what de design looks like for the moment: