Into building with tubes again, need pointers!

[mnordbye]

I'm into building again, after a break due to studies.

Decided i want to build a tube pedal for my bass, to go in front of my transistor bass amp. I'm thinking something like a tube pedal with some variable volume boost and the possibility for some slight overdrive. Not fuzzy, but kind of smooth.

Is there any such projects around? Couldn't find ayny with the search function.

If not, i'm willing to try designing one from the ground up. But then i need some pointers for you tube-pedal-freaks around here!  I've built tube amps, but i realize when it comes to tube pedals, i'm completely blank. I need to know how to get tubes to work on 9V etc., what components are needed, and what tubes i can/should use (sub-mini, standard etc.)

Thanks!
Magnus

[defaced]

First decide if you want to do low voltage (less than 50v) or high voltage (100v to 400v).  If you do high voltage, then any tube preamp in any amp can be adapted into a pedal format very easily.  If you do low voltage, then start looking at some of the other tube pedal projects that have been posted here. 

[MikeH]

Have you built a valve caster?  It does what you want more or less.  How dirty it gets depends on how hot of a signal you hit it with.  My bass has active pickups and it gets my valve caster pretty dirty.

[liquids]

Have you built a valve caster?  It does what you want more or less.  How dirty it gets depends on how hot of a signal you hit it with.  My bass has active pickups and it gets my valve caster pretty dirty.

I've not build the valvecaster, but I know what you mean.  This can often be remedied by a simple buffer, following a simple volume control, into said pedal.  Then you have a crude gain control over 'input clipping,' as part of the tone, with the consistency that a buffer brings....without the dirt level having to be completely at the mercy of the pickups plugged into the device.

Or, you could leave out the buffer and just wire up a passive volume control at the front, if you'd rather that kind of thing.

[CynicalMan]

You could also go submini:
www.diystompboxes.com/smfforum/index.php?topic=71350.0
www.diystompboxes.com/smfforum/index.php?topic=70533.0

[mnordbye]

Thanks for the replies, i'll check out the links.

I have an idea of what i'm gonna do now, gonna set up a dual gain stage circuit on my breadboard and work my way from there. I'm probably gonna start out with no tone control, only a volume pot, and a gain pot in between the stages.

But i still need to find out how to power and use the tubes, whether it'll be standard tubes or those submini tubes. I do have some 12AX7s and 12AT7s here, and i think i'll start out with them.

And yes, i want this thing to work with a 9V adapter. 18V would work too, as i can always use a voltage doubler chip etc. inside to make this work (or just an 18V adapter).

So the question is, does anyone have any pointers for me to get the tubes working with the lower input voltage?

DEFACED: I guess i'm going for high voltage then (100v - 400v). How can i make this work with pedal adapters at 9V or 18V?

Oh, and i'll try breadboarding the valvecaster too, if i can get a hold of some of those subminis. Might have one lying around.

Thanks,
Magnus

[defaced]

DEFACED: I guess i'm going for high voltage then (100v - 400v). How can i make this work with pedal adapters at 9V or 18V?

Yes, see the Mesa Bottle Rocket thread.  I stepped the guy building that through the design process.  It's pretty easy once you see it. 

[amptramp]

Check out the amplifier calculator section in this site:

http://ampbooks.com/

This lets the ordinary experimenter do the same job as an engineer.

[mnordbye]

Thanks guys! I'll report back when i come up with something useful.

Magnus