"Delirium" 5672 Submini Pentode Tremolo/Boost

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
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frequencycentral
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Post by frequencycentral »

I've done quite a few designs using these little pentodes, and here's a trem! The tremolo speed goes from 'machine gun fast' to 'is it still on?' slow. Even slower speeds can be obtained by changing the speed pot for 47K or 100k, but for a useable range 22K or 27K is just fine. I power all my effects off a 12 volt supply, which with this effect means a decent amount of clean boost is available in addition to the tremolo. Powering it off 9 volts will give less boost.

I've included a few options for powering the 5672's heater in the schematic.

If you want to add a rate LED, just hang it off the output of the second opamp (before the depth control) which a suitable resistor ( I used 1K on the breadboard).

5672's can be a little microphonic, so it's worth using some foam around the tube to pad them. Don't expect them to glow - they don't! They don't heat up either.

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lolbou
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Post by lolbou »

The tube acts like a voltage control ampllifier in here, that's it? Is it really giving something to the sound?

A very cute design anyway, thank you! :applause:
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lolbou wrote:The tube acts like a voltage control ampllifier in here, that's it? Is it really giving something to the sound?

A very cute design anyway, thank you! :applause:
Thanks!

That's almost correct, although a VCA is normally closed without a control voltage present. The depth control mixes between the LFO and the 47K/43K voltage divider in this case, so a voltage is always present at the 5672's grid 2.

Does it give something to the sound? I don't know, do tubes give something to the sound? :shock:

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lolbou
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Post by lolbou »

frequencycentral wrote: That's almost correct, although a VCA is normally closed without a control voltage present. The depth control mixes between the LFO and the 47K/43K voltage divider in this case, so a voltage is always present at the 5672's grid 2.
Man, that's a clear answer, I like it!! :applause:
frequencycentral wrote:Does it give something to the sound? I don't know, do tubes give something to the sound?
I meant (in french actually) "does it add a real tube sound, or is it just doing the same than, say, a FET?"...

Do low voltage ones have the same tonal characteristics as the "big" ones?

But it's really cool to share your devices with us (me!) ignorant(s)...
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Post by frequencycentral »

lolbou wrote:
frequencycentral wrote: I meant (in french actually) "does it add a real tube sound, or is it just doing the same than, say, a FET?"...

Do low voltage ones have the same tonal characteristics as the "big" ones?
As for having a unique sound, it's probably more appropriate for others to comment on that. Each effect, be it BJT, FET, IC or tube has it's own sound. My stuff just provides an alternative.

Tubes are fun, and tube projects stretch my skills as there are so few points of reference for this kind of stuff. With solid state design, it's always a case of looking over your shoulder at what others have done before, there's always an answer. I now find that I understand tubes more than I do solid state due to my incessant breadboarding.

Tubes are less prone to the effects of EMP and solar flares/sunspot activity. You solid state guys will be green when the Ruskies nuke us all with EMP and all that's left in a functional state are my tube pedals! Plus, my tube stuff will work on Venus, where solid state will fail within a matter of seconds.

Ultimately though, I just do it because I'm Steampunk!

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Post by earthtonesaudio »

Go Rad Hard!

Rick, I think your LFO might not do so well on Venus... :horsey:
rocklander wrote:hairsplitting and semantics aren't exactly the same thing though.. we may need two contests for that.

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Post by lolbou »

And tin solder doesn't like venusian sulfuric acid rains too...

I came to FETs because it was easier for me to experiment with (low voltages and no heating) and in order to understand better the tube circuits (which are roughly close, I know)... But your minitube designs help to understand both, thank you! :D
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Post by frequencycentral »

earthtonesaudio wrote:Go Rad Hard!

Rick, I think your LFO might not do so well on Venus... :horsey:
Eek! Busted by Alex! I hoped no one would notice that flaw in my argument....

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