Zvex - Box of Metal

culturejam · Post by **culturejam** » 25 Dec 2008, 06:50

This is a Vexter Series Box of Metal, serial number BM 0058.

I did a quick 10-minute jam session with this pedal, and overall I actually dig it quite a bit. Not a ton of versatility as far as ranges of drive go, but it does what it does well, in my opinion. I think it's worth reversing, but I doubt the gate part of the circuit is really needed. Mine doesn't have a lot of hum or buzz, even with the gain dimed. The EQ is pretty good, and with the treble cranked, it can cop DS-1 type gritty scratchy distortion.

Anyway, I've attached some preliminary gut shots to get the ball rolling. For whoever decides to tackle this, I can take additional photos as necessary. Just let me know what you need.

Five shots are attached here, with the rest to follow in another post.

culturejam · Post by **culturejam** » 25 Dec 2008, 06:52

Additional gut shots.

Notice that the op-amps have been buffed to remove the part numbers.

Whoismarykelly · Post by **Whoismarykelly** » 25 Dec 2008, 18:41

I wouldn't buff part numbers off. I think I would relabel parts so anything less than removing the part and measuring it would yield a crappy clone.

borislavgajic · Post by **borislavgajic** » 25 Dec 2008, 20:18

and optocoupler is for gate function???
boris

bumblebee · Post by **bumblebee** » 25 Dec 2008, 22:13

Thanks for the pics!

DWBH · Post by **DWBH** » 25 Dec 2008, 22:44

borislavgajic wrote:and optocoupler is for gate function???
boris

Yes.
I think Zachary Vex said it was an optical noise gate. But I don't wan't to put words in other people's mouths, so I must say - I may be wrong.

culturejam · Post by **culturejam** » 26 Dec 2008, 02:45

bumblebee wrote:Thanks for the pics!

You bet, brother.

DWBH wrote:
borislavgajic wrote:and optocoupler is for gate function???
boris
Yes.
I think Zachary Vex said it was an optical noise gate. But I don't wan't to put words in other people's mouths, so I must say - I may be wrong.

I can't imagine it being for anything else.

Also, I spelled it "Zvez" in the title post, so could a mod please correct it whenever you guys around to it? Thanks.

kurtlives · Post by **kurtlives** » 26 Dec 2008, 03:54

5K reverse audio pot

Hmmmm........

culturejam · Post by **culturejam** » 26 Dec 2008, 04:20

kurtlives wrote:5K reverse audio pot

Hmmmm........

Well, it does say "Crackle Okay" on the case right next to that pot, so there ain't mystery here.

borislavgajic · Post by **borislavgajic** » 26 Dec 2008, 19:42

DWBH wrote:
borislavgajic wrote:and optocoupler is for gate function???
boris
Yes.
I think Zachary Vex said it was an optical noise gate. But I don't wan't to put words in other people's mouths, so I must say - I may be wrong.

Nobels have something similar in some pedals..........

MKB · Post by **MKB** » 26 Dec 2008, 20:05

Judging from the pot values I'd guess he has a Marshall tone stack in it.

bajaman · Post by **bajaman** » 26 Dec 2008, 21:25

and at least 5 super hard on variants before the tone stack

any chance of some more pics - the two dil op amps??? appear to be for the opto limiter circuit and / or voltage multiplication / regulation. most of the SHO stages after the initial cascode stage have their sources tied to ground (only one crackle

).
Please take photos from further out to avoid fish eye effect - also please measure length and depth of board please.
It has been fun Christmas relaxation for me - almost completed the board layout etc.
cheers
bajaman

soulsonic · Post by **soulsonic** » 26 Dec 2008, 22:24

I think the compass is possibly one of the best tools ever created. It does all these complex math functions with just a simple mechanical method! It measures and divides all in one action.
I love it!

culturejam · Post by **culturejam** » 26 Dec 2008, 22:42

bajaman wrote:\any chance of some more pics - the two dil op amps??? appear to be for the opto limiter circuit and / or voltage multiplication / regulation.

Sure thing.

bajaman wrote:Please take photos from further out to avoid fish eye effect - also please measure length and depth of board please.

I'm using the macro mode on my point-and-shoot. If I pull further out, you can't read the tiny values as well, but I'll try it anyway. Maybe I can stand further away but zoom in? We'll see what happens.

You rock, Baja!

culturejam · Post by **culturejam** » 26 Dec 2008, 23:01

BajaMan, here's what I just shot:

I got some tighter shots of the op amps. I started at one side of the board, and took 4 photos (to cover the whole board area).

If this isn't what you were looking for, let me know. I'll take as many photos as needed.

I tried pulling away a bit and shooting with regular (non-macro) mode, but the minimum focusing distance is about 1.5 meters when at the longest focal length. Those photos don't look very useful.

Also, if you want the full resolution images (it's a 10 megapixel camera), send me a PM and I can email them to you.

Board Dimensions: Width - 3.75 inches. Height - 1 inch

bajaman · Post by **bajaman** » 27 Dec 2008, 04:36

Okay - so here it is - a 5 stage super hard on with a modified Marshall tone stack. I have not bothered to trace the Noise gate power supply and detectuion circuitry , but have the analog signal path sorted out - no surprises here!!
After the treble control the signal feeds through a fet which can be activated by the noise gate circuitry, but essentially ( leaving the series fet out which is only activated when the gate circuitry is used), the signal is fed from the treble control wiper to the top of the 100k log volume pot, then through the wiper (of the volume pot) to a 10uf coupling capacitor to the output (footswitch). there is also a 100k resistor from the output side of this coupling capacitor to ground.
The diagram sketch below has several unknown value capacitors, but I am sure you can work them out from the Rox Of Bock schematic and any Marshall JCM 800 amplifier circuit. If you have a capacitance function on your multimeter perhaps you may like to measure them for us. All the stages are BS170 mosfets including the last stage incorrectly drawn as a jfet

Cheers
Steve

members/bajaman/Baja/Vzex/MoxofBetalfirstsketch.jpg

chris_d · Post by **chris_d** » 27 Dec 2008, 04:57

Interesting. This is actually similar to something i was going to mess with. Specifically, taking an amp layout but instead of using the J201 style Runoffgroove amp sim thing, using BS170 stages, which i prefer the sound of. I was going to build it off the Bogner XTC schematic, but i may just build this one as is to start with.

I am curious about the noise gate as well. I don't really need one for guitar use, and will likely build this without it, but i am curious as to what Vex used anyhow.

Anyhow, i like the cascaded BS170s in the Box Of Rock, and i think i might wind up digging this one as well.

Thanks for the gutshots and tracings!

-chris

culturejam · Post by **culturejam** » 27 Dec 2008, 05:09

Awesome!!

Thanks for the hard work, Bajaman.

I do have a capacitance meter function on my DMM, but it's only for leaded components. It's just two little slots that you slide the leads into.

By the way, what role do the op amps play? Some part of the gate?

soulsonic · Post by **soulsonic** » 27 Dec 2008, 06:42

chris_d wrote:Interesting. This is actually similar to something i was going to mess with. Specifically, taking an amp layout but instead of using the J201 style Runoffgroove amp sim thing, using BS170 stages, which i prefer the sound of. I was going to build it off the Bogner XTC schematic, but i may just build this one as is to start with.

I did this once; it worked and sounded pretty decent, but it was really noisy and seemed unnecessarily complex for what it did.

bajaman · Post by **bajaman** » 27 Dec 2008, 07:21

I do have a capacitance meter function on my DMM, but it's only for leaded components. It's just two little slots that you slide the leads into

Okay

Just grab some insulated hookup wire - strip, twist and tin both ends with solder - plug into capacitance slots and use the other two ends and place them against the ends of the smd capacitors ( the cream coloured flat slab things).
Let us know what the readings are and we can add them to the schematic.
cheers
bajaman

Zvex - Box of Metal [traced]