Ramble FX - Marvel Drive 1.0  [traced]

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PedalBlotter
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Post by PedalBlotter »

The Ramble FX Marvel Drive is a nice sounding Plexi Pedal with parallel blending inputs, like a real amp.
It sounds amazing !!, i have one here (V1.0) borrowed and make a schematic.
That´s the first time i analyze a pedal and make a schematic.
So consider me, and check the schematic, if there are any errors in it.
If someone can make a verolayout, that would be great :hug:

Image

download this schematic

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Frank_NH
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Post by Frank_NH »

Nice! I just listened to some of the online demos of the Marvel Drive and it's probably one the best Plexi pedals I've ever heard - just awesome. Bring on the vero! :D

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PedalBlotter
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Post by PedalBlotter »

yes, please someone make a vero ! :D

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coldcraft
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Post by coldcraft »

the pin connections on the FETs are incorrect. compare to another JFET overdrive to see what i mean. could you post a higher resolution image?
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PedalBlotter
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Post by PedalBlotter »

click on "download this schematic" under that image for a high resolution.

what u mean with incorrect pin connection ?

ah shit, did i mistake gate and source ?

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Post by mirosol »

Yup. Gates and sources are in reverse.
+m
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PedalBlotter
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Post by PedalBlotter »

Ok i changed it:


Image

download this schematic

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tictac
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Post by tictac »

That 820 ohm source resistor on the first gain stage isn't grounded; doesn't look right.....

:hmmm:

TT

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PedalBlotter
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Post by PedalBlotter »

Yes, u are right.

Fixed it, and the one 1M at Q4 Drain was wrong too :oops:

Actually schematic:

https://dl.dropboxusercontent.com/u/357 ... otter3.png

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Post by PedalBlotter »

Some Pics:

Image

There is a Wima 4700p cap in, on the pcb it says 470pf...
Under that 180pf Micas, the board says 220pf

Image

---

Image

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PedalBlotter
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Post by PedalBlotter »

Ah sry again.

The 470pf is right, my false...
Wima is a 470pf/100 cap

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PedalBlotter
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Post by PedalBlotter »

Damn, isn't here a edit funktion ?

Anyway, the resistor below the Styroflex is for the LED (+)

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RambleFX
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Post by RambleFX »

Looks good :thumbsup

It's basically the input triode stages of a 1987x Marshall (in JFET form) into a mini-booster, into another JFET stage. That's one of the very first Marvel Drives. The ones built now have relay bypass switching, a presence control, and several tweaks. They're much cleaner builds too :oops:

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PedalBlotter
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Post by PedalBlotter »

Thank you RambleFX for verify my amateur work :oops:

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Post by IvIark »

Q4 still doesn't look right to me:

Code: Select all

Q3 drain > Q4 emitter > 100n > 100K > Q5 gate
                 V
                1u > Q4 gate
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Post by PedalBlotter »

Hmm, i checked the circuit a hundred times i think. :scratch:
it must be right like on the schematic ? :hmmm: :

Actually Version V3

Pics from Q3 and Q4:

Image

----

Image

....

Image

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jubal81
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Post by jubal81 »

I redrew for clarity. Looks pretty reasonable. The only thing I see as weird are the parallel 220uF & 100uF caps on the source of the 'normal' j201 input.
Here's a link to the full image

Image

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Post by IvIark »

Aaah muamp! I couldn't see the wood for the trees
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

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Post by IvIark »

jubal81 wrote:I redrew for clarity. Looks pretty reasonable. The only thing I see as weird are the parallel 220uF & 100uF caps on the source of the 'normal' j201 input.
The 1987X has 330u from source to ground in that position.
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

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Post by PedalBlotter »

Nice work jubal81.
Looks clearer and cleaner than my experiment :oops:

i see, the treble/normal pots are backwards on my drawing :|


C10 is a polarized 1uF 50 Volt + to Gate Q4

C6 is a polarized 0,68uf 100 Volt

if this is necessary ?

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