Monolith Fuzz Oracle

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Whoismarykelly
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Post by Whoismarykelly »

A few photos before I send this off in a trade. I can answer any questions you have.

Volume pot (far left): A500K
Color pot (center): B250K w/ DPDT. DPDT switches between a 12k and 100k resistor in the tone stack between the 6800pf mustard and the 1uf tropical fish.
Density pot (far right): B1M w/ 4.7pf and 470K resistor across lugs 2 and 3. Note: this pot is the first thing the signal hits and as an input gain control it is not very effective. When not at max, the sound is flubby, farty, and gated to the point of being useless. Any builds would be better off skipping this control. I suspect the builder wanted to build a guitar volume control into the pedal to simulate cleanup. Since this pedal does not clean up at all, the control is of questionable value.

The radial electro is a 100uf power filter cap
The axial electro is a 22uf

Power appears to be typical negative ground but both transistors are PNP Germanium.

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allmonochrome
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Post by allmonochrome »

Schematic (it should be correct)
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hazelwould
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Post by hazelwould »

That's a cool looking build!

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briggs
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Post by briggs »

I love those things, they are the size of a house but still great builds. Are both transistors OC76?
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Whoismarykelly
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Post by Whoismarykelly »

briggs wrote:I love those things, they are the size of a house but still great builds. Are both transistors OC76?
They could be. Mine has an OC75 for Q1 and an OC75 for Q2.

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allmonochrome
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Post by allmonochrome »

briggs wrote:I love those things, they are the size of a house but still great builds. Are both transistors OC76?
i have a gutshot of one with two OC76s.

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allmonochrome
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Post by allmonochrome »

corrected schematic:
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playon
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Post by playon »

Interesting. Mine has OC76s, you might have to sort through quite a few germanium trannys to find one as hot (300 hfe) for Q2. They aren't that easy to find in that gain range, but I'm sure any high gain ge tranny would work in that spot, such as 2N1307, etc. I'm wondering how critical this is, as some were made with OC75s? Those aren't generally very high gain.

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Whoismarykelly
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Post by Whoismarykelly »

playon wrote:Interesting. Mine has OC76s, you might have to sort through quite a few germanium trannys to find one as hot (300 hfe) for Q2. They aren't that easy to find in that gain range, but I'm sure any high gain ge tranny would work in that spot, such as 2N1307, etc. I'm wondering how critical this is, as some were made with OC75s? Those aren't generally very high gain.
OC75 was the Q1 in mine. Small Bear sells high gain germaniums so a check there would be a good place to start.

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playon
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Post by playon »

Was yours from the recent batch he sent out, or from last year?

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puppiesonacid
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Post by puppiesonacid »

looks like a box of crayons...hahahahah

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Whoismarykelly
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Post by Whoismarykelly »

playon wrote:Was yours from the recent batch he sent out, or from last year?
Well I ordered it in November 2008 and was told 3 weeks but IIRC it took about 2 months to show up.

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playon
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Post by playon »

You can say what you like, but it is a good sounding pedal...

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hazelwould
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Post by hazelwould »

So is this a fuzz face with a tone control, PTP?

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playon
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Post by playon »

Whoismarykelly wrote:
playon wrote:Was yours from the recent batch he sent out, or from last year?
Well I ordered it in November 2008 and was told 3 weeks but IIRC it took about 2 months to show up.
The same for me, I ordered in late Dec. & didn't get it until early April. Also mine was quite noisy (hiss) when the volume was turned up, even with the gain down, noticeably noisier than any of my other fuzz-type pedals.

The Oracle is more like a distortion than a typical fuzz to me.

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beedotman
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Post by beedotman »

bump with tagboard layout 8)
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mictester
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Post by mictester »

allmonochrome wrote:Schematic (it should be correct)
You're going to get some serious crackle as the two pots on the RHS of the circuit are adjusted - they've both got DC on them!
"Why is it humming?" "Because it doesn't know the words!"

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lasermonkey
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Post by lasermonkey »

Anyone else built one of these? It's a nice sounding fuzz, but the density pot doesn't seem to do much at all, apart from add a touch of shrillness to the end if the note decay.

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lead2203
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Post by lead2203 »

lasermonkey wrote:Anyone else built one of these? It's a nice sounding fuzz, but the density pot doesn't seem to do much at all, apart from add a touch of shrillness to the end if the note decay.
I found a mistake.....I think.
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lasermonkey
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Post by lasermonkey »

Many thanks-it works like a charm now. Rolling back the guitar's volume pot cleans it up very nicely. I like this one a lot.

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