zwizz army knife overdrive

allesz · Post by **allesz** » 08 Nov 2009, 13:30

I just came up with this small effect.
It is a single transistor booster, overdrive and distortion.
Right now it stays on the breadboard, but I plan to put it in a box soon.
It sounds good to my ears and the input caps network can change pretty much the sound of the unit: going up with gain it’s better to reduce the input cap value (available values are 15 nF, 62 nF, 115 nF and 162 nF) wile a big cap and little gain can make an interesting light overdrive.
Someone who prefers knobs can put two caps (one small and one big) and a pot to go beetwen heavy and light sounds, but I am a switch type of person (and I had three spst switches around).
I also tryed a "prebass" pot as found on the rocktron austin gold but it did not work: it was cutting too much signal.
The single clipping diode (a tribute to Hemmo’s Bazz Fuss) is great to smoot out the distortion texture when gain is near maximum or can yeld little bakgroud drive sound to clean settings; it reduces the output a little... but not too much.
If someone is interested in my project, I will be happy to share my small work; if someone has suggestions to make it better I will be happy too.

RnFR · Post by **RnFR** » 08 Nov 2009, 18:44

cool! i'm going to move it to the ready to build section.

himister · Post by **himister** » 09 Nov 2009, 00:55

I like "funny" boosters, OD's. Now it's really ready to build.
Enjoy it.

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PCB transfer and layout:

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allesz · Post by **allesz** » 09 Nov 2009, 23:32

Thank you very much for the interest and for the pcb.
Actually I just finished it, I did it on a prefboard (5 cm x 2,5 cm) during lunch time; tonite, after kids and wife went to sleep, I put it in a box (made during lunchtime too, monday is a good day for me

) and finished it. It works fine. The transistor is a bc319c (I think it's important to say, because gain change between a, b and c types); other transistors I tryed (bc107, bc108c, 2n2222, bc 547b) had not enough gain, for me at least; I tryed a mpsa13 too, but it was no better than the bc319c (maybe I should have change the 100k resistance and 10k pot values to make it work good)

I will post some picture and some soundclip, or even a youtube video if I can (I never did it before). I just wait a little to try the thing in reharsal room: at home I cannot play loud enough to test it properly, and to see how it fits in a band situation.

I took so much info on this site that I am really flattered if you find my small work interesting. I just feel in debt with you and all the diy world.

By the way, if you want one (super boutique finish with real stains of sweat and blood) it is just 350 Euros.

himister · Post by **himister** » 09 Nov 2009, 23:51

Thank you very much for the interest and for the pcb.

Hey no worries. I'm glad to help. I'm pretty fast with these small stuff so I saw the chance to help someone, and I enjoy helping and contributing.

As I said I like boosters and small cute things, need patience and lot of passion to build it, specially from scratch, so I took interest in this one. I'll add it in my collection.

(maybe I should have change the 100k resistance and 10k pot values to make it work good)

Try to increase the volume pot value and you'll see the difference in combination with other dirt pedals, more gain, less gain.
Typical output impedance in many pedal effects would be around 10k (at least for Boss) so in combination in front of other dirt pedals or even amp you'll see how much gain is produced.

I will post some picture and some soundclip, or even a youtube video if I can (I never did it before). I just wait a little to try the thing in reharsal room: at home I cannot play loud enough to test it properly, and to see how it fits in a band situation.

That would be really nice.

I took so much info on this site that I am really flattered if you find my small work interesting. I just feel in debt with you and all the diy world.

As someone would say, don't sweat... and keep the good work.

By the way, if you want one (super boutique finish with real stains of sweat and blood) it is just 350 Euros.

I would like to see that one for that kind of money.

Cheers.

jrod · Post by **jrod** » 12 Nov 2009, 17:21

Cool project, allesz. Thanks!

I was wondering if you tried two clipping diodes?

allesz · Post by **allesz** » 13 Nov 2009, 17:28

Yes, I tryed two diode clippers (1n4148s in opposite directions), a single germanium diode, and led clippers too (single and in couple).
With two 1n4148 the output level decreases quite a lot (too much for my taste) and the sound is somewhat similar to the single diode configuration; germanium has a good smooth sound but with little volume (maybe if you put two in series...); I like diode clippers in general (and they give more output volume) but, in this case, I felt the sound was too similar to the sound without clippers; you know, I just wanted an option to a different sound, if the sound does not get different what's the point?

Anyway everybody has his personal vision about clipping stages, for me you can use germanium, zeners, fet, mosfets... dead rats, whatever. And if it is good to you it's ok.

The most interesting part of this pedal is having overdrive, and maybe a little bit of distortion, sounds without diodes (it is the first pedal I own that can do so). The clipper option is just to get some proper, and traditional, distortion sound available in the same pedal, if it's needed; but I don't plan to rely too much on this switch.

allesz · Post by **allesz** » 16 Nov 2009, 15:40

Ok, here it is a link to a video demo of the zvizz drive.

Apart from terrible playing, speaking, and audio quality I think you will be able to appreciate the fine qualities of the unit and... avoid making one yourself

allesz · Post by **allesz** » 21 Nov 2009, 09:28

I tryed it yesterday on reharsals on a transistor amp (a 100 watt peavey transtube, quite a good amp for me) and I think I will put one lower value cap on the imput (4,7 nF; 15 nF (turned out the best one) and 100 nF);
With a tube amp you have more range of dirt, on a solid state amp if you want dirt you have to stay near maximum gain, and the diode option became very useful.
My bandmates liked the sound of the unit.

allesz · Post by **allesz** » 01 Feb 2010, 12:18

Just a small update: I recently made another unit to fit it in an old mxr enclosure. I did not want to drill new holes so I decided to put just a switch (in place of the led) for the diode clipper.
I put an input cap of 10nF and a 220 pF filter cap.
the new unit sounds very good (I noticed I rarely used the big 100nF input cap anyway) and, when going in a tube amp the diode clipper becomes just a bonus (the overdrive gets very good overdriving the input) but when going in a transistor amp the clipper becomes very usefull to get some proper drive sound.

IvIark · Post by **IvIark** » 01 Feb 2010, 14:35

I love these little one transistor dirt boxes. Here's a tag layout with different input caps and the 220pF as suggested.

allesz · Post by **allesz** » 05 Feb 2010, 21:35

I like your chioce of input caps; lately I tryed 6,8 nF (beautifull sound, treblebooster but not too shrill), I went for 10nF in the end because it cuts out little less bass frequencies, it gets more versatile.
By the way 4,7 nF works great with my valve junior and painfully too trebly with a 100w marshall valvestate clean channel.

the 220pF cap makes the effect a little less wild (expecially on maximum gain) and more polite, 100pf maybe is too much wilderness, but sometimes it can be good too: I have to buy, and try some 150pF cap.

so many option in a so simple project.

Recently I have seen a video demo of the analogman beano boost (it sounds very good, even vithout a gain pot) and I thought that is incredible how much sound you can get with a so simple pedal.

allesz · Post by **allesz** » 08 Feb 2010, 17:22

Ok, a new and small update.
I will go back to 100pF filter cap on my second unit: With the 220 pF cap I experienced (it is difficult to ear those things at first and on every amp...) the loss of some (good) treble;
100 pF to my ears tames the hiss of the unit (it is not too noisy anyway) but still lets the natural treble of the guitar to pass and shine throug the amp; bigger caps makes some beautifull things too but... I just decided I prefer the small one (for this week

).

allesz · Post by **allesz** » 09 Mar 2010, 21:47

I recently developed this project:

I was making a second unit and I decided to go back on the breadboard before putting the effect toghether: I wanted to experiment some more and try out the asenio novo tube sound overdrive I found on this same site (a good sounding one knob device). I ended up converting my first booster into this new thing.

In the end I mixed things and ideas from Arsenio Novo, Hemmo P. (bazz fuss and buzz box) and some switch. The result is something way more flexible than the original zwizz army drive project.

The second stage adds some gain, more output and better clarity; now you can go from clean (almost) treble booste, to overdrive, distortion, (almost) fuzz, octave fuzz, (almost) clean octave.... I still don't believe it myself.
The (switchable) germanium diode on the second stage opens up for new sounds, it really sounds good with the gain maxed and no clipping diodes.
As input caps I went for low values (I find them the more usefull, the second version has just a 15 nF input cap).

Downsides are that output levels changes between the various options, you can compensate it with the volume, but it gets non practical to change on the fly (maybe on the same song) between different sounds (for example a second footswitch would be of little use in this pedal).
The gain pot (same on the first zvizz army drive) is somewat noisy, it does not crakle but gives some scratchiness.

Give it a try if you want, you will not be disapponited, and help eliminate the downsides if you can.

RnFR · Post by **RnFR** » 10 Mar 2010, 17:39

you could get quite a bit more gain by lowering the 10K emitter resistor on the second stage. you have it set as if it is in the minimum gain position of the first stage. try around 2K2 to start, and reduce from there if you want more drive.

allesz · Post by **allesz** » 11 Mar 2010, 18:16

Hallo, actually the second stage had a lot more gain originally on my breadboard. The problem is that, if you increase the gain on the second transistor, you loose almost all the clean boost ability of the effect (maybe I should have tried just a buffer stage).

Maybe this feature could be another switchable turbo option, or a second gain knob.

Now on my breadboard I have the arsenio novo overdrive to experiment; but I will give a listen to the "turbo" option you described too.