Vacuum Tube Wah

Paul Marossy · January 24, 2005, 08:57:40 PM

QuoteEasier with a PCB and an aluminum L-bracket for the tube socket.

Yeah, that's true. I was thinking about the pictures that puretube posted when I said it could be done PTP...

petemoore · January 24, 2005, 09:47:26 PM

I 'Think' I'd want the tube and inductor isolated from each other, to keep noises from hitting the SP?. Seems logical...[?].
Better question is...what are the components that lend themselves to producing unwanted noise, and allow for isolation shielding to be used?
Transformer, tube, inductor, SP wires, HV supply wires...I'd think selective isolation design would take up some of the room for improvement as far as noise.
Any suggestions as to the best places to start reducing noise?

Paul Marossy · January 24, 2005, 11:27:59 PM

The two main sources of noise would be from the 12VAC heater supply and more so from any transformers within the wah enclosure. I had a wall wart close to my vintage CryBaby wah pedal, and it picked up hum even though the circuit is in that metal enclosure. It wasn't too self-evident until you used something like a Boss Metal Zone with it, and then, massive hum and noise! I moved the wall wart to the opposite end of the pedalboard, problem solved. I'm not convinced that any internal shielding would help against this sort of EMI that transformers radiate, unless maybe it's a toroidal type?

puretube · January 25, 2005, 01:59:59 AM

Quote from: R.G.So, pure, those look really cool. How about showing us the schematic for that, as I did for mine?

Thanks for the flattery - I`m lucky to have withstood the urge of "letting everybody know", for 25 years;
- it`s currently a so called `trade secret` between E-H and me -

QuoteThanks for the pics! Interesting. I bet it could be done PTP with some careful thought.

Quote from: R.G.Easier with a PCB and an aluminum L-bracket for the tube socket.

another solution (pic) coming up, soon. (opto-version).
edit: here it is... :

(Paul and someothers know those pix...)

QuoteAnyone know who to credit for this tube wah circuit?

Quote from: R.G.That ... was... a trademark infringement, right pure?

Yes, I was very angry when the schem appeared a couple of years ago,
and I couldn`t find the originator...

QuoteHmm...Thanks puretube. You've given me a good idea! I can now get power transformers without the filament winding, and just use voltage regs....They'd be cleaner!

Quote from: R.G.And hotter.... = 13.2watts of power to get rid of,...

that`d be a nice foot-warmer, yes!

QuoteI remember a time when that GEO article had a variable capacitor rather than a Wah pot, so I never had a second look.

That`s the Eric Barbour circuit, IIRC...

Quotecan a purchase on of 'em PCB layout books from you?)

R.G.: that reminds me of another recent thread, where somebody wanted to purchase a PCB from your site, where it says: send an email - but it shows no address...

puretube · January 25, 2005, 02:06:03 AM

Quote from: Marcos - MunkyJust a dumb question: what is the difference in the sound between a inductor wah and a tube wah?..

an inductor wah can be transistor-, IC-, or tube-powered;
a Tube-Wah can use an inductor- or other kind of filtering;

Quote from: Paul MarossyI'm not convinced that any internal shielding would help against this sort of EMI that transformers radiate ...

so-called MuMetal will shield that "Dynamohum";
toroidals will emit much less than conventional ones.

Quote from: petemoore...Any suggestions as to the best places to start reducing noise?

quite like you already suggested...like in every tube project, and with
the proper layout of any inductor-based design...

Sic · January 25, 2005, 02:28:10 AM

R.G.,

Csj and i were also interested in purchasing one of your books, Clay said he e-mailed you but got no response. I'm sure you get alot of e-mails though =D

Anyhow, i know alot of people around here would be really excited if you made another batch of books.

Puretube, im sure keeping a secret that long about something that you are so passionate about has to just about drive you to the edge of insanity...

I can't even seem to keep christmas presents from my Girlfriend...

:oops:

puretube · January 25, 2005, 02:50:54 AM

Quote from: Sic
Puretube, im sure keeping a secret that long about something that you are so passionate about has to just about drive you to the edge of insanity...
:oops:

It almost for sure will ruin you financially, when the passion even doesn`t give you the time to work a "regular" job... :wink:

beware!!

Tim Escobedo · January 25, 2005, 02:53:06 AM

ISTR another Eric Barbour design that was a Twin T, using a pentode.

puretube · January 25, 2005, 03:07:27 AM

that`s the one with EF86, and the triple varicap, mentioned before.

Tim Escobedo · January 25, 2005, 03:13:04 AM

I just found it. It's actually supposed to be a simple tube VCF.

http://www.cgs.synth.net/tube/vcf.html

puretube · January 25, 2005, 03:23:40 AM

oops - yes Tim - sorry, I mixed up yet another schem -
the before mentioned Barbour I referred to was in fact the big core plus the triple varicap...

casey · January 25, 2005, 09:11:32 AM

[/quote]And Eric's version of a vacuum tube wah uses a multi-henry iron cored inductor and a - big - AM radio style moving plate variable cap to sweep the wah resonance. Sourcing that variable cap is a modest-to-major pain, depending on how many old tube style AM radios you have lying about.[/quote]

i collect AM tube radios from the 30's 40's and 50's....so not a problem...

R.G. · January 25, 2005, 09:15:29 AM

Quotei collect AM tube radios from the 30's 40's and 50's....so not a problem...

Then you're one of the few people who would not be back here moaning about Mouser not having them.

'course, if I collected tube AM radios, gutting one for the tuning cap for a wah is the last thing I'd want to do with one of my babies...

casey · January 25, 2005, 09:20:05 AM

Quote from: R.G.
Quotei collect AM tube radios from the 30's 40's and 50's....so not a problem...
Then you're one of the few people who would not be back here moaning about Mouser not having them.

'course, if I collected tube AM radios, gutting one for the tuning cap for a wah is the last thing I'd want to do with one of my babies...

yeah, i didnt say that i was going to do it...

i just said that i could! :roll:

i do have a radio though that is really messed up, but the vari-cap dooga-ma-hicky (technical term) is good in it though.

Paul Marossy · January 25, 2005, 10:21:27 AM

Quotetoroidals will emit much less than conventional ones.

Yes, and that gives me a thought - I could try RG's tube wah project using a small toroidial transformer inside the enclosure and the 500mA wall wart, if I can find one... Hmmm.

TryingToDo613 · March 16, 2006, 04:08:23 PM

Hello??? Blink Blink Blink. Doesn't anyone else want to hear it before asking the guy how you build it? I've made alot of stuff over the years that no sound came out of. Does it work? How does it sound? Did I miss the sound clips or has a KGB virus preventing me from seeing the link?

Oh, I'd buy your book too RG. -ph

markr04 · March 16, 2006, 05:27:34 PM

Quote from: TryingToDo613 on March 16, 2006, 04:08:23 PM
Hello??? Blink Blink Blink. Doesn't anyone else want to hear it before asking the guy how you build it? I've made alot of stuff over the years that no sound came out of. Does it work? How does it sound? Did I miss the sound clips or has a KGB virus preventing me from seeing the link?

No. It has a tube in it, so it *must* be [insert superlative here].

Kidding aside, some might be interested in the challenge alone, regardless of how it sounds (assuming it's no worse than a Crybaby). DIY's whole appeal to me is the challenge.

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Vacuum Tube Wah