Big Muff Octave Up

[SprinkleSpraycan]

I have a triangle muff on my breadboard and find that lifting the first stage diodes (D3,D4) create an octave up, the more gain of course the more pronounced the octave. I've been using 914 diodes. Going back and forth between BC549, 337 and 338-25 transistors. The octave is always present despite transistor choice though. Im into it, dont get me wrong, its cool. I want to know whats causing it though because ive lifted diodes on other muff layouts and never had this effect. Thoughts?

[Dormammu]

Is this really an octave up? According to the diagram, this should be an octave down.
Sound samples would help to better understand.

[SprinkleSpraycan]

Is this really an octave up? According to the diagram, this should be an octave down.
Sound samples would help to better understand.

Dang your right. I just heard the clang and octave UP is what lodged in my mind. It's down. Haha.

But still...what's the cause?

[Dormammu]

A common practice is to reduce the values of the input and interstage caps, which remove excess bass.
Try C1 33-68 nF and interstage 0.1 mF.

[Mark Hammer]

The Sola Supa Tonebender was essentially a Big Muff, but with the diodes from the first clipping stage removed (although one could easily say the Big Muff was a Supa Tonebender with diodes added to the first stage).  I've installed toggles to lift that first set of diodes in several of my builds, and I have never heard an octave up.

[Dormammu]

I have never heard an octave up

The OP dude made a little mistake — an octave lower.   

[Mark Hammer]

I have never heard an octave up

The OP dude made a little mistake — an octave lower.   

Perhaps. but I've never heard that either.  Now, SOME distortions, like the Jordan Bosstone,  can be nudged to produce a very audible octave down under certain circumstances.  But unless the OP has done a LOT more than lift the diodes in that stage, and sub some transistors, I can't see how an octave down would result.

[SprinkleSpraycan]

I have never heard an octave up

The OP dude made a little mistake — an octave lower.   

Perhaps. but I've never heard that either.  Now, SOME distortions, like the Jordan Bosstone,  can be nudged to produce a very audible octave down under certain circumstances.  But unless the OP has done a LOT more than lift the diodes in that stage, and sub some transistors, I can't see how an octave down would result.

yes, messing with the bias of a bosstone can get a really good lower octave.

I haven't changed anything but the said transistors and the lifted diodes.

[Dormammu]

Now, SOME distortions, like the Jordan Bosstone,  can be nudged to produce a very audible octave down under certain circumstances.  But unless the OP has done a LOT more than lift the diodes in that stage, and sub some transistors, I can't see how an octave down would result.

Of course, it's difficult to judge this without audio samples. But I've gotten similar results messing with caps at almost any overdrive or distortion.
I can't say if it's an octave or not, but it's a very bassy sound.

[antonis]

I promised myself I'd never again deal with Dornammu's bunkums, but...

Mixin up octave with bass indicates the need for ENT doctor..
(and an elementary unerstanding of waverforms..)

P.S.
As far as I know, octave down effect needs some kind of flip-flop configuration implementation..
(like the Q8/Q9 bi-stable multivibrator in Coloursound Octivider)

[Mark Hammer]

As far as I know, octave down effect needs some kind of flip-flop configuration implementation..

I might agree with that, BUT the case of the Bosstone contradicts it.  And I don't say this because of something I heard someone claim.  I modded my own Bosstone and was as puzzled and surprised as anyone by the appearance of clearly audible octave-down.  It's not reliable as an octave-down effect, but it is certainly there.  I just wish I understood why.

[antonis]

Of course I take your word for that, Mark..
(but, as you said above, it needs a lot of modifications to form a sub-oscillator..)

I think Electric Druid might enlighten us for the present case..

[PRR]

> some kind of flip-flop

A lot of circuits will flip-flop if grossly overdriven.

[Dormammu]

> some kind of flip-flop

A lot of circuits will flip-flop if grossly overdriven.

For sure, definitely.

[antonis]

A lot of circuits will flip-flop if grossly overdriven.

Like a CE amp of gain x47..??

[amptramp]

If you look at what the diodes are intended to do, they are supposed to clip the top and bottom from the signals and generate waveforms with a lot of odd-order harmonics - 3rd, 5th, 7th etc.  But the biasing of these transistor stages is affected by the fact that the 1µF capacitors restrict the diodes from having an equal effect at all frequencies.  The transistor pulls down with a different availability of current than the collector resistor pulls up.  You may get some interaction of the voltage on the capacitor with the resistance that pulls it up that may make some subharmonics happen.  This could be set with the R-C time constant between the 1 µF capacitor and the input impedance seen looking into the input of the stage.

The dividers in my Minshall Model E organ are single triodes with tuned blocking dividers that use capacitor and resistor tuning at one frequency to have the triode respond to the input once, then store enough charge with the R-C time constant in the grid to prevent it from responding to the next input pulse but it discharges enough to respond to the following input pulse.  If you are getting subharmonics, this is probably the mechanism.

[SprinkleSpraycan]

If you look at what the diodes are intended to do, they are supposed to clip the top and bottom from the signals and generate waveforms with a lot of odd-order harmonics - 3rd, 5th, 7th etc.  But the biasing of these transistor stages is affected by the fact that the 1µF capacitors restrict the diodes from having an equal effect at all frequencies.  The transistor pulls down with a different availability of current than the collector resistor pulls up.  You may get some interaction of the voltage on the capacitor with the resistance that pulls it up that may make some subharmonics happen.  This could be set with the R-C time constant between the 1 µF capacitor and the input impedance seen looking into the input of the stage.

The dividers in my Minshall Model E organ are single triodes with tuned blocking dividers that use capacitor and resistor tuning at one frequency to have the triode respond to the input once, then store enough charge with the R-C time constant in the grid to prevent it from responding to the next input pulse but it discharges enough to respond to the following input pulse.  If you are getting subharmonics, this is probably the mechanism.

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