Shocktave question?

[doug0147]

Hi-

I made the Shocktave circuit last night on my bread board. At first all I got was a loud buzzy fuzz sound when I hit the strings really hard. I was using this really bulky 630V .1uf  capacitor at the input so I decide to try a different cap there. For some reason I put in a 47 uF and it now made fuzz, but I'm not so sure about the octave part. Maybe it's there, but I can't notice it much. The octave output is definitely putting out a signal though, but it seems to be mostly fuzz.

Is the octave effect on this thing supposed to be really subtle? Does it make any sense that it would work with the 47uF cap instead of the .1 uF cap?

Here is the schematic.

http://www.diystompboxes.com/analogalchemy/sch/shocktave.html

Thanks

[mantella]

Hi,
I'm getting the exact same effect. Fuzz, but no octave.
I'm wondering if you ever managed to figure it out?

[oldrocker]

The Shocktave is not subtle by any standard.  The octave down is distorted (not clean) but the octave is pronounced.  I have built two of these.  One on perfboard for me and one on PCB for my brother.  My brother said he loved the monster octave down and wants me to build another for a friend of his.  Watch out for the transistor configuration at the tail end of the circuit.  This originally messed me up the first time I built it. 

Below is an inside shot.

http://i218.photobucket.com/albums/cc93/ftrock/st10q.jpg

[DDD]

The Shocktave is a masterpiece. The most simple but effective octave-down circuit ever. If assembled properly it works well.
So, check for the mistakes once more.

[cab42]

Soundsample here (by RDV):

http://fatboy.ssguitar.com/Samples/Shoctave.mp3

Regards

Carsten

[chi_boy]

Soundsample here (by RDV):

http://fatboy.ssguitar.com/Samples/Shoctave.mp3

Regards

Carsten

Well that sold me.  Another one added to the list.   

[doug0147]

Thanks for getting back to me on this. I ended up taking all the peices out of the breadboard and moved on. But I did print out  a layout for when I felt like giving it another try. I think now is the time! I'll let you know how it goes.

[doug0147]

OK, so I built the thing. It sort of works, but the octave is very inconsistent. Also, I used a 1k resistor instead of the gain pot. Any suggestions for getting it like the one in the clip?

[oldrocker]

OK the best thing to try is using only the bridge pickup.  Use the tone control on your guitar and roll it down to give it less high and more bass.  This works the best for this type of effect.

[doug0147]

Thanks I guess you're saying it is what it is. One other thing I  would like to mention. I used a 1n4148 diode instead of the 1n914. I think those are interchangable, but I might be wrong.

[oldrocker]

In my previous post I wrote bridge pickup.  That's wrong I meant neck pickup. Sorry I wasn't thinking straight that day.  As for the diodes you are correct they are pretty much the same.

[synthmonger]

I don't have any 2N5089 hand I and I tried subbing for 2n3904's and BC547 with no luck. I got oscillation fuzz but couldn't quite get an octave down effect.

Just how well does it track?

[Derringer]

it'll get sloppy on chords  but single notes track well

stuff on the low E isn't real pretty, but the A string on up do ok

actually ... nothing about the shocktave is pretty, but that's its charm 

check out http://www.myspace.com/doubleplanetband
on the song G.I.S. you can hear my shocktave at 2:08 and then again at the very end of the song starting at about 2:59 (that's the shocktave before a crybaby into another fuzz)

[synthmonger]

So anyone think I should try getting the specific transistors and not sup them for other NPNs? I tried other ones with no luck.

[Derringer]

yeah, try it

maybe it needs that high gain to do the trick


but make sure you go over every other connection in triplicate too

[ddpawel]

The Shocktave is not subtle by any standard.  The octave down is distorted (not clean) but the octave is pronounced.  I have built two of these.  One on perfboard for me and one on PCB for my brother.  My brother said he loved the monster octave down and wants me to build another for a friend of his.  Watch out for the transistor configuration at the tail end of the circuit.  This originally messed me up the first time I built it. 

Below is an inside shot.

http://i218.photobucket.com/albums/cc93/ftrock/st10q.jpg

Probably the key for the good octave are paired transistors, caps and resistors. I've built this with 1% metalized, 5% MKT caps and 2n5089 transistors, but ... no good octave. Everything has to be paired to 0.1 % I think.
Is there possibility to build 2 octave down by adding only voltage to frequency converter and multivibrator? I'm begginer and I don't know schematic is correct:

I don't know is it correct or there is enough gain to drive second stage?
Could someone help me?

[Quackzed]

i don't know about adding a second stage ...
but i do know that it can be a bit tricky to get the right amount of gain going into the flipflop section...
if the tone is very gated and dies too quick, you could try a 5k, or even 2k on the second transistors collector for more gain...
when set up properly it should give you a good sustained tone.

[oldrocker]

I don't know about pairing components but I built to of these with off the shelf Radio Hack parts.  As for two stages I have no idea.  IMHO the gain knob is a must to dial in the octave to be more pronounced.

[ddpawel]

So...
I'll try built this 2-stage version in this or next week (don't have much time right now) and post a report. Maybe this will give more pronounced 1-octave or maybe something like MXR Blue Box, it would be nice. Let's give it a try.

[ddpawel]

I have another idea. Maybe is it good to build Op-amp based Schmitt trigger with very high gain and drive two stages of Shocktave multivibrators? !!!!!!!!!!!!! But will the shocktave divider stages handle this?

What are you think about this?