Zvex - Machine

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Cortex
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Post by Cortex »

Hello good people of FSB! Let me start by saying I really REALLY appreciate everything you're doing here. Cheers fellow pedal lovers!

I breadboarded the Machine using madbean's schematic but I have problems with it. It seems to me either people are satisfied with the results or we that have problems, share the same ones. I am becoming a little frustrated cause this is an easy build.
When I attach the output pot where it is pointed on the schematic, the effect is noisy and VERY very quiet, I am not even sure it has all the characteristics of a Machine.
But when I take my output from the source of the BS170 as Is the current situation on my breadboard showed here =>

My MAchine On A Breadboard

then I am getting something very similar to the Machine, I do get that scream with a sustaining note, that's pretty much the reason I built this, to have that in my solos, and the nastiness of course :D
I am also getting the best results when I turn the IN all the way, OUT also (but this is not exclusively), and LIMIT almost all the way down!! With limit all the way up, there's beautiful gain...but I feel like it loses the scream little by little.

Please look at the picture of my breadboard, see if I'm doin' something wrong. (remember, layed down like in the picture, pots are, respectively, IN, OUT, LIMIT, only because I'm getting almost nothing if i connect it like on the schematics)

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Cortex
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Post by Cortex »

Tnx for helping me on so short notice :mrgreen:

Anyway I have it going and working now. The schematics verified, again.

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bram
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Post by bram »

I've built the pedal according to the trevor jones layout. I just 2k for the gain 1 and 2. I'm not yet sure if linear pots wouldn't have been better for the job?

Anyway, awful pedal, weird sounds. Does nice things with drum loops as well. The 2 gain knobs make it more versatile!
So: trevor's layout verified again. thanks!

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bram
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Post by bram »

oops, I listened to the machine samples on the zvex site, mr. vex says exactly the same about the drums and the machine. I didn't know that. So, he's right :D

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soggybag
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Post by soggybag »

the3secondrule wrote:Hi, I'm going to build one of these for myself very soon, Using this layout:

Just wondering how I would add the switch to use the SHO only. I'm bit of a n000b, so if someone could show me on this layout, I'd much appreciate it :-)

Cheers,

J

[ Image ]
I just built up this layout. Worked the first try. To be Honest it was the second try. I had forgotten to include the last transistor on the right. Only the EBC lettering is shown on the layout so its easy to miss. It's also to in the original, it's reverse polarity protection scheme. Once I added the last transistor it fired up no problem.

Actually this will fit B sized box but, you'd have to give give up the battery and possibly the DC jack.
After testing I sized it for a box. I had originally planned to use a B sized box. Though this layout looks like it would fit, I don't think it will, unless you used some very narrow 1/4" jacks. No worries I have a BB box I can use.

Image

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soggybag
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Post by soggybag »

Image
Image

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Post by soggybag »

I built this version and it works pretty well. it's a year or more later and I'm realizing that this has an extra pot. The original doesn't use this pot. I'm also realizing that the response of the Gain pots is all in the last 25% of the travel.

I'm not convinced the second gain pot has that great an effect. Though you can get some subtle differences.

The parts list calls for linear pots, K5B and K2B. Since these SHO stages reverse log pots even out the gain across the travel of the knob. I used a K10B pot with a 10k resistor across lugs 1 and 3. This seemed to emulate a reverse log 5k.

I'm having some trouble getting usable tones across the whole range of the controls. I feel there is not enough gain from one stage to the next. I removed R6 (22K) this seemed to increase the overall gain.

If anyone has good Machine mods please feel free to post them. I'd like to mod this thing into something I like.


trjones1 wrote:Just thought I'd add my vero layout to the thread. I hope it's not too confusing to decipher. I designed it for board mounted pots such as these ones I get from futurlec: http://futurlec.com/Potentiometers/POT5K.shtml. The extra bits under the output pot are a polarity protection circuit from Geofex to guard against using the wrong power supply.

[ Image ]

This is the finished and mounted circuit:
[ Image ].

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