Tube boost + overdrive running off a 9 volt battery

[volund]

Hi! Quest about the dual circuit. C3, way is it so large?

[motorhead]

it's what I suspected, the miniature tubes have completely different characteristics
so it's not supposed to run with a starved plate, but it became that way by changing the tube
i'll go with a high voltage design, since I can't find a miniature tube, apparently it will get closer to the tube amp sound

[jrmcgrath13]

Motorhead... perhaps you should just try building one.  A 12AU7 tube can be obtained cheaply on ebay or through various other websites.  Or, go look up some of the ones that have been built on youtube.  You'll see that they have a very nice sound, and indeed work quite well.  

[Renegadrian]

[MikeH]

I think everyone is right- Obviously, the circuit works.  That's not in question.  The point of the project isn't to recreate an optimally functioning 12**7 tube gain stage.  If you want that, just go out and grab any tube amp schematic and recreate the first stage:  Bam.  Done. 

The purpose of this project was to allow pedal builders that don't work with high voltages to do something with tubes, without cooking their insides.

Is a 12**7 tube meant to run on 12 volts?  No.  Does it?  Yes.  Does it sound good at 12v?  I'd say good, but not magical.  Would it sound better at 100v?  Probably, but that would defeat the purpose of this project.

[Boogdish]

Maybe the circuit needs a "For Entertainment Purposes Only" disclaimer.

[zambo]

disclaimer is a great idea. 

[Regan]

Hey everybody,
I haven't posted in years,, but every once in awhile pop in and check things out and this time had to comment,, sorry if this comes across a bit harsh.
Motorhead,, have you worked with tubes before? it doesn't sound like it and I hope you take care when you build your high voltage pedal.
As for the starved plate designs being a "chance" thing,,,,, I imagine it was just "chance" that the tube driver,, the mini boogee, the tonebone classic and hot british,, the aria tube overdrive,, the nady tube overdrive,, the behringer tube overdrive,, the various vox tube pedals,, the various maxon tube pedals, and so on and so forth were developed.
As you will notice,, tube curves are exactly that,, curves,,, they don't drop off totally at 9.7 volts or 15 volts,,, they curve. Do they sound the same as at higher voltages?,,, no,,, does that mean they sound bad? absolutely not. Most of the characteristics you want in an overdrive will be in a starved plate design,, breakup,, compression etc,,,,,NOT LINEARITY,,,, will it sound like a triple rectifier, absolutely not,,, neither does a tube screamer,, a boss overdrive,, or any other overdrive out there(not that a triple rectifier is at all linear).
As for your comment on the mini tubes,,,, the 12u7 follows the same  general curves as the 12au7, physically has the exact same plate structure, sounds the same ( yes I have both) and quite possibly is just a 12au7 relabeled. Yes the subminiatures follow different curves but again,,, linearity is not the goal!
The fact is,,, its been done time and time again,, and this design has been researched so thoroughly by the guys in this thread that it has me a bit speechless that you would pop in 80 pages later and act like it was a fluke,,, ummm, what?
I mean you could build it and try it,, its so simple it would take an evening at most, or don't bother because you don't believe it works(even if the thousands of pedals made with a starved plate 12au7),, but most people are here to learn too and if thats your case,, then remember its hard to learn when your close minded.
Regan

[anchovie]

i'll go with a high voltage design, since I can't find a miniature tube, apparently it will get closer to the tube amp sound

Be careful, it might just be pure speculation that a tube preamp sounds like a tube preamp. 

[Renegadrian]

cut
most people are here to learn too and if thats your case,, then remember its hard to learn when your close minded.
/cut

That sentence makes me think of my first Valvy - it was one of my first pedals made and yeah I had a great surprise when done - how can a tube with just a few components and working at 12V can sound so good!!! it left me like http://www.youtube.com/watch?v=QkjD3D5FgmE 

[motorhead]

well, that's exactly what I'll do when my tubes will arrive: ECC802 S and ECC803 S

"The ECC802S is the uber premium version of the ECC82/12AU7 tube with extra internal structure, pure copper grid supports and 10,000 hour life ratings. These tubes were made in the Siemens Munich, Germany factory"

and I'll build both the valvecaster and probably some fender or vox or whatever preamp, and let you guys know the difference

that's right, i never used tubes before, but I'll survive a shock of 100 to 250 V, hopefully 

if I survive, the power amp is next 

[anchovie]

and I'll build both the valvecaster and probably some fender or vox or whatever preamp, and let you guys know the difference

No offence, but I think everyone already accepts that the Valvecaster is a pedal circuit. It's for use with a preamp, not instead of one.

[Renegadrian]

ECC803 S is a 12AX7 - you won't get great results with that tube in a Valvy...

[zambo]

Why cant we use valvy as a pre amp? Forgive the ignorance on my part. Ps....what comes out the business end of a valvy ohms wise and voltage wise?

[dimitarmk]

Can I use this schematic as a preamp for an tube amp project I'm working on? 

[motorhead]

I guess (an educated guess  ) that you can't use it as a preamp, since plate voltage needs to be higher than 12 V, in order to achieve some sort of gain out of a tube - look at the curves

or you can add an op-amp at the end, and increase the overall gain, but you won't be able to call that a tube preamp

ecc802 or ecc82 is equivalent to 12AU7, so it should work with valvy

[dano12]

  After two and a half years and over eighty pages of this thread we find that all of our many Valvecasters don't work?   

Finally, you guys have caught on to my evil plan.

[MikeH]

that's right, i never used tubes before, but I'll survive a shock of 100 to 250 V, hopefully 

if I survive, the power amp is next 

You might want to suggest that your wife/roommate/family, or whomever you live with, take a CPR class.  And offer to pay for it too. 

Seriously though, read up on some safety before trying anything high voltage.

[frequencycentral]

.......since plate voltage needs to be higher than 12 V, in order to achieve some sort of gain out of a tube..............

I don't even think it's worth arguing the point any further. If you choose not to believe this then that's your call. Whatever. There are worse facts to choose not to believe I guess. I despair. I don't think I can bear to look at this thread any longer.

[zambo]

I have used the valvecaster as a preamp for a lm386 power amp ( or lack of power amp at a raging .3 watts!!) and it seemed to work fine. I dont know what a "real" power amp wants to see at the input and if it matches the output of a valvecaster. If I only knowed the answer to these two things...... It seems like the answer was in these 83 pages somewhere .