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DIY Stompboxes => Building your own stompbox => Topic started by: doug0147 on April 07, 2009, 11:58:14 AM

Title: Shocktave question?
Post by: doug0147 on April 07, 2009, 11:58:14 AM
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 ;D
Title: Re: Shocktave question?
Post by: mantella on May 28, 2009, 11:00:32 AM
Hi,
I'm getting the exact same effect. Fuzz, but no octave.
I'm wondering if you ever managed to figure it out?
Title: Re: Shocktave question?
Post by: oldrocker on May 28, 2009, 11:58:55 AM
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. 
(http://i218.photobucket.com/albums/cc93/ftrock/st3qn.jpg)
Below is an inside shot.

http://i218.photobucket.com/albums/cc93/ftrock/st10q.jpg
Title: Re: Shocktave question?
Post by: DDD on May 28, 2009, 03:29:45 PM
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.
Title: Re: Shocktave question?
Post by: cab42 on May 28, 2009, 05:05:39 PM
Soundsample here (by RDV):

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

Regards

Carsten

Title: Re: Shocktave question?
Post by: chi_boy on May 29, 2009, 12:42:39 AM
Soundsample here (by RDV):

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

Regards

Carsten



Well that sold me.  Another one added to the list.   :icon_cool:
Title: Re: Shocktave question?
Post by: doug0147 on May 29, 2009, 02:11:50 PM
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.
Title: Re: Shocktave question?
Post by: doug0147 on May 30, 2009, 06:33:20 PM
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?
Title: Re: Shocktave question?
Post by: oldrocker on May 30, 2009, 09:55:23 PM
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.
Title: Re: Shocktave question?
Post by: doug0147 on May 30, 2009, 10:05:57 PM
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.
Title: Re: Shocktave question?
Post by: oldrocker on May 31, 2009, 12:37:06 PM
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.
Title: Re: Shocktave question?
Post by: synthmonger on June 23, 2009, 08:42:43 AM
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?
Title: Re: Shocktave question?
Post by: Derringer on June 23, 2009, 08:57:55 AM
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  ;D

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)

Title: Re: Shocktave question?
Post by: synthmonger on June 25, 2009, 06:40:37 PM
So anyone think I should try getting the specific transistors and not sup them for other NPNs? I tried other ones with no luck.
Title: Re: Shocktave question?
Post by: Derringer on June 25, 2009, 06:59:57 PM
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
Title: Re: Shocktave question?
Post by: ddpawel on February 14, 2010, 04:06:53 PM
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. 
(http://i218.photobucket.com/albums/cc93/ftrock/st3qn.jpg)
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:
(http://img514.imageshack.us/img514/8163/moda.png)
I don't know is it correct or there is enough gain to drive second stage?
Could someone help me?
Title: Re: Shocktave question?
Post by: Quackzed on February 14, 2010, 04:40:59 PM
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.


Title: Re: Shocktave question?
Post by: oldrocker on February 14, 2010, 08:46:09 PM
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.
Title: Re: Shocktave question?
Post by: ddpawel on February 15, 2010, 11:39:37 AM
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.
Title: Re: Shocktave question?
Post by: ddpawel on February 15, 2010, 12:33:04 PM
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?
Title: Re: Shocktave question?
Post by: soggybag on February 15, 2010, 02:23:26 PM
Speaking of matching transistors. I always thought this might be built best using a transistor array like the LM3046/3086. This way the transistors would be matched. Everything would be on one chip, which might make for a more convenient build.

I gave it a try once on a breadboard some years ago without any luck. Either I made a mistake somewhere or the transistors were to low gain. Or a combination of the two.  I still think this would be the way to go to
Title: Re: Shocktave question?
Post by: ddpawel on February 15, 2010, 02:42:42 PM
Speaking of matching transistors. I always thought this might be built best using a transistor array like the LM3046/3086. This way the transistors would be matched. Everything would be on one chip, which might make for a more convenient build.

I gave it a try once on a breadboard some years ago without any luck. Either I made a mistake somewhere or the transistors were to low gain. Or a combination of the two.  I still think this would be the way to go to

I've seen project with these transistor arrays - www.jhaible.de/tau/jh_tau.html (http://www.jhaible.de/tau/jh_tau.html), relly good phaser.
LM3046 arrays have low hfe=110.

But as I see on http://www.falstad.com/circuit/e-multivib-a.html (http://www.falstad.com/circuit/e-multivib-a.html), there shouldn't be difference in signal if hfe is 100 to 10000, so it should work. Of course if hfe is bigger it has better characteristics. Maybe pair of MPSA13 can help?

And what about Op-amp schmitt trigger driving multivibrators? Can it be better than two transistors like in  regular Shocktave?
Title: Re: Shocktave question?
Post by: caburron on October 22, 2015, 02:59:36 AM
AM getting the same result :poor or lack of octave sound ,i thing that there's not enough voltage on the oscilator.maybe the schematic is wrong,becouse i check the shin ei octaver in the oscilator ,and has his on 9 volts ,instead of chopped voltage from the transistor base of this circuit,i  need help in this one ,what  i did wrong? The fuzz is fine.Iwas trying to get the "everyone's a winner " guitar sound .Have auditioned many fuzz octave boxes on youtube and no luck.THE fuzz part is a little like gated or sputtered on the song and  a littlle octave down and then up .thx
Title: Re: Shocktave question?
Post by: Quackzed on October 22, 2015, 10:19:31 AM
try a booster in front or overdrive with the vol cranked...