Trotsky Drive: Flubby and Fartng Low End

[railhead]

I've been tinkering with the Trotsky Drive for a few hours, and I'm finding that it really flubs and farts-out on the low end. I'm using a 1N34A and a 1N914 for clipping, and I've removed the bright cut cap. I'm also using a 2N2222A for the tran.

I've been swapping C1 to thin out the input, but I'm still not loving it.

Has anyone ever added a tone control to this circuit? How did you mod your Trotsky?

[railhead]

No one?

[raulgrell]

Just a guess, but, if I have learnt correctly, this might may sense:

Try adding a cap in series with the clipping diodes. This should limit the bass frequencies that get clipped, resulting in a cleaner, clearer bass sound... play with values...

[railhead]

The Trot already has a 100nF cap from collector -> diodes -> output. I guess I could jack with that cap rather than the input cap...

[ambulancevoice]

i think he means like this

shit, i forgot to flip the diode

[raulgrell]

yeah, that's what I meant... However, playing with the 100nf cap could do some good.

Also, IIRC a higher gain transistor can help reduce the very low end you get from some circuits... If the drive is too high though, just use a smaller feedback tranny.

EDIT: Actually, I'm not really sure about the tranny thing... maybe it's the opposite: A lower gain transistor will reduce the very HIGH end... Bah, humbug...

[the_random_hero]

Adding a simple high-pass filter before the output should work.

[raulgrell]

That would work if there were simply too much bass in the circuit... but IIRC, the flabby/farty aspect of it caused by the distortion of very low frequencies, not necessarily their existance.

[railhead]

I'll try the inline cap and see what happens.

[raulgrell]

How'd it work?

[nooneknows]

I don't know this circuit (I don't have the schem) but, generally, you can de-fart farting circuits reducing the basses in the earlier stages, that means lowering the cap values in series with the signal (not the caps going to ground).

[raulgrell]

Generally, that is true, but the original post said he'd lowered the input cap with no success. So, as it seems the low end signal is getting clipped so much it is causing sound issues, adding a cap in series to reduce the amount of low frequencies that pass through that path to ground where the signal is clipped, will result in a cleaner, less farty bass... I think...

If I'm correct, this "mod" will also reduce the highs in the signal.

[railhead]

Thanks for the replies -- I just haven't had a chance to sit and try this yet.

One thing I did do, though, was swap the placement of the 1N34 and 1N914 diodes. I had been using D1 as the 914 and D2 as the 34, and swapping their locations tightened things up a bit.

Still need to try the cap inline, though...

[raulgrell]

how does chaniging the orientation of diodes affect the frequency response of the tone though?

[Caferacernoc]

"how does chaniging the orientation of diodes affect the frequency response of the tone though?"

Well, the diodes are clipping asymetrically. The transistor is a single ended boost. It also probably clips a little asymetrically. At least until it's fully saturated. So there will be a slightly different sound depending on the diode orientation. You can either add to the asymetry or even it out back towards symmetry depending on which way you flip the diodes to ground. The degree of asymetrical clip also affects the the sound downstream of the effect. Like straight into a tube amp's preamp which also clips asymetrically in it's first stage. That's what I think anyway!   ;-)

[ambulancevoice]

Thanks for the replies -- I just haven't had a chance to sit and try this yet.

One thing I did do, though, was swap the placement of the 1N34 and 1N914 diodes. I had been using D1 as the 914 and D2 as the 34, and swapping their locations tightened things up a bit.

Still need to try the cap inline, though...

this makes sense to me real horrorshow
in a regular clipping configuration, one diode clips the high end signal, and the the other clips the low end (which is why there reversed from each other)
in the case of the Trostky/Electra drive, the germ diodes actually produce more distortion, because they have less output voltage, unlike the silicon, which produces less distortion and more output voltage, and now, according to railhead (i can call you railhead? wait youve got a name, Maury) he had the germ in the low end clipping postition before, so the low end was getting more distortion than the top end cause the silicon was there (still producing a mild amount of distortion mind you). Now that hes switched it, and its tightened up, suggests circumstances of the previous diode configuration where making the low end more farty etc
this, also suggests that the diodes are possibly whats causing the low end shit
try that cap, i think it will work

[ambulancevoice]

....
ok, ignore what i wrote above, and just try the cap

[railhead]

I still haven't tried the ideas above, opting for a more "elegant" solution by implementing the Stupidly Wonderful Tone Control 2. Here's a merged schematic showing how I did this:



It works -- but not with a very wide sweep. As I'm still somewhat new to building, I'm not sure what to change the values to in an attempt to get a wider sweep of tone (I want more treble boost/low cut). Right now, I'm using Orman's recommended values: R1=10k, R2=47k, C1=.022uF.

My goal is to not hardwire the tone so that I can use this pedal with my thin Tele, as well as my fat Les Paul.