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DIY Stompboxes => Building your own stompbox => Topic started by: Hal on May 07, 2004, 10:09:24 PM

Title: Tube rectafiers as clipping diodes?
Post by: Hal on May 07, 2004, 10:09:24 PM
would it work???
Title: Tube rectafiers as clipping diodes?
Post by: Paul Marossy on May 07, 2004, 10:16:51 PM
My intuition tells me "no", but I am no expert on that one...
Why would you want to do that anyway? Just wonderin' what your thinking is on that.
Title: Tube rectafiers as clipping diodes?
Post by: Hal on May 07, 2004, 10:22:06 PM
PURE TUBE MRX distortion plus!  No Semiconductors in sight!!

no not really.  Just wondering if it has been tried, and what it would sound like...

I think the problem would lay in the fact that you not only need a larger signal to push into the tube, but it would also not have a definite voltage drop....

i should try it though, at some point...or someone should cuz i dont have tubes or a power supply... :-D
Title: Tube rectafiers as clipping diodes?
Post by: Paul Marossy on May 07, 2004, 10:28:36 PM
Tube rectifiers need an AC voltage to do what they do. So in theory, they could work for a guitar signal. But, I think that because of how they are constructed, you would get some problems with hum. They are meant for rectifying 120VAC, not small signals like one from a preamp section.
Once again, I'm not an expert, but that is my take on it.
Title: Tube rectafiers as clipping diodes?
Post by: Hal on May 07, 2004, 10:55:19 PM
tube rectafier = diode?

simply, doesn't it just allow electrons to flow from the filament to the plate, but not the plate to the filament...??

And yea, i think the voltage would be a problem :-D...unless a guitar signal is boosted up...
Title: Tube rectafiers as clipping diodes?
Post by: puretube on May 08, 2004, 03:39:11 AM
you can wire a "small signal" triode (e.g. 12AX7) as a diode (=rectifier),
and if you do that twice, you can get nice tube-diode-clipping including doubling, like shown here:
(http://www.puretube.com/link-page-Dateien/T-FUZZ%20D-C%20sml%20cor.2.jpg)

(this one additionally has the equivalent of the "E-H Tube-Zipper" filter circuit in front of the diode-stage -
no semics in sight - )
Title: Tube rectafiers as clipping diodes?
Post by: Paul Marossy on May 09, 2004, 08:47:24 PM
A 12AX7 wired as a diode? I could see that working. A real rectifier tube would cause some problems, I would think. I think the problem would be hum induced into the signal chain. Tube rectifiers move a lot of heater current compared to a preamp tube, and they usually have a series of filter caps after them that filter out the hum. Using it directly in the signal path would probably not work as one would like. But the preamp tube is a different story...

Just thinkin' out loud, so to speak.
Title: Tube rectafiers as clipping diodes?
Post by: Phorhas on May 10, 2004, 02:33:01 AM
Quoteyou can wire a "small signal" triode (e.g. 12AX7) as a diode (=rectifier),
and if you do that twice, you can get nice tube-diode-clipping including doubling, like shown here:

Would that ACTUALLY WORK?! and would it sound that good that it would worth to get into all the mess of tube (compared to a simple D+ crkt)...

Would it work with a sub-mini triode?
Title: Tube rectafiers as clipping diodes?
Post by: Nick123 on May 10, 2004, 04:00:59 AM
AFAIK  Fender  uses  12AX7  as  clipping  device  in Roc Pro  amps.
Title: Tube rectafiers as clipping diodes?
Post by: Athin on May 10, 2004, 04:13:11 AM
take look at the McTube [@ tonepad.com 4 example]
Title: Tube rectafiers as clipping diodes?
Post by: Pedro Freitas on May 10, 2004, 07:07:00 AM
It works. Once I drove a 6AL5 duo-diode with a 6AV6 triode and got just mild clipping. Only voltage the diodes required were the filament's voltage.

Pedro
Title: Tube rectafiers as clipping diodes?
Post by: Paul Marossy on May 10, 2004, 10:10:04 AM
"Only voltage the diodes required were the filament's voltage."

Very interesting.
Title: Tube rectafiers as clipping diodes?
Post by: Pedro Freitas on May 10, 2004, 10:41:51 AM
Yeah, this duo-diode thingies were used as detectors or something in tube radios, ence they will handle low signals. And were made by the millions. They usualy go dirt cheap because no one ever has any use for them.
Anyway, I needed a faily large signal boost before the diodes to got decent clipping.

Pedro
Title: Tube rectafiers as clipping diodes?
Post by: Ben N on May 10, 2004, 12:29:58 PM
Hardly seems worth it, right?  I mean, is, say a 12ax7 configured as a clipping pair, going to sound better than using that same triode as a conventional pair of gain stages, with whatever plate voltage and bias produces whatever quality of distortion you please?
Title: Tube rectafiers as clipping diodes?
Post by: puretube on May 11, 2004, 01:00:25 PM
who says better? - different !
would Electro-Harmonix have licensed the Tube- Fuzz (TM),
if it wouldn`t sound?

It sure sounds other than a Ge, Si, LED, Schottky.....

btw.: this was the first one, surnamed "P-Jackulator"...
(http://www.puretube.com/link-page-Dateien/P-Jackulator-0.JPG)