Mad Professor - Amber Drive

roseblood11 · Post by **roseblood11** » 08 Jan 2015, 21:32

This thing sounds really amazing:

Any infos?

It's surely worth degooping...

Ice-9 · Post by **Ice-9** » 08 Jan 2015, 22:39

Sounds quite nice, it's orange and I would guess at some sort of modified DS1 type circuit. That just a pure guess on sound and mainly colour but it wouldn't be a big surprise if I am correct.

roseblood11 · Post by **roseblood11** » 12 Jan 2015, 16:31

Someone at musikding.de degooped the pcb.
http://forum.musikding.de/vb/forum/diy- ... 1079774597

It's a modified version of the Fire Red Fuzz, a variation of the Big Muff. FET's instead of diodes in the first clipping stage and a FET output stage.
The schematic isn't verified yet...

: Mad Professor Amber Drive

roseblood11 · Post by **roseblood11** » 12 Jan 2015, 19:12

After listeing to the sound samples again, I think that the tone control isn't ideal for overdrive sounds here (but I don't like it in a standard Big Muff as well...). Maybe a James tonestack would be better, I remember that there was a variation named "James Muff" some years ago, maybe I even built that on vero?!? Gotta give it a try...

Ice-9 · Post by **Ice-9** » 14 Jan 2015, 11:44

roseblood11 wrote:Someone at musikding.de degooped the pcb.
http://forum.musikding.de/vb/forum/diy- ... 1079774597

It's a modified version of the Fire Red Fuzz, a variation of the Big Muff. FET's instead of diodes in the first clipping stage and a FET output stage.
The schematic isn't verified yet...

Lol, I was miles off course.

assche · Post by **assche** » 13 Sep 2015, 10:17

I think this schematic missed 10k resistor for 2nd BC550C

roseblood11 · Post by **roseblood11** » 14 Sep 2015, 00:56

It might be the 12k between the two 470k's at the upper edge of the board? At least, that's what someone guessed at musikding.de...

...and the drain resistor of the last FET might be selected - maybe it should be replaced with a trimpot?

assche · Post by **assche** » 14 Sep 2015, 05:05

yes. that One.

but, is it 12k? 12k Color Code is brown-red-black-red-brown
it might be 10k

mictester · Post by **mictester** » 14 Sep 2015, 06:17

it is 12k with those markings.

: Amber Drive

There may be a couple of other errors too:

The FETs will just work as diodes wired like that - there's no point in using them. Either the way they're drawn is wrong or you could get the same result with a couple of cheap 1N4148s.

I don't think that's 1M in the tone stack - it wouldn't do anything. It's more likely to be 15k - please re-check.

It never ceases to amaze me that >>90% of boutique pedals are Fuzz Faces, Tube-screamers or Big Muffs!

Having said that, I like re-working the Big Muff with different clippers and tone circuits - there's a huge range of sounds to be found there......

assche · Post by **assche** » 14 Sep 2015, 07:49

thanks for new schematic!

but it's not 12k
color code of that resister is brown-black-black-red-brown. it means 10k

tone stack value might be right
between 47n and '8'numbered cap at bottom of the board, 10n 22k 100n 1M in there

roseblood11 · Post by **roseblood11** » 14 Sep 2015, 12:11

I guess that the FET's are used the same way as in the Stone Grey Distortion: https://www.freestompboxes.org/viewtopic ... distortion

assche · Post by **assche** » 15 Sep 2015, 12:40

I built it today. Very nice sound!!!

bucksears · Post by **bucksears** » 17 Sep 2015, 14:43

I read that it's supposed to be the same overdrive as the 'Golden Cello', but minus the built-in delay.
i.e. that Eric Johnson 'violin sound' in a box

Dingleberry · Post by **Dingleberry** » 20 Sep 2015, 14:53

It will be easy to mod a fire red fuzz into amber overdrive. Just few resistor, cap and diode changes.

BJF · Post by **BJF** » 27 Jul 2016, 14:38

Dingleberry wrote:It will be easy to mod a fire red fuzz into amber overdrive. Just few resistor, cap and diode changes.

Hi there,

Well without disclosing things I can say that is exactly what I did and they specifically asked me to use FRF for this which to me as a designer is a limitation
But hey if I get the limitations I'd work with those regardless and oh yes I had Dean Farley that is a Dumble expert having played more that 35 clones for his verdict of how close to the real deal and yes Dean is good friends with Howard however I am not and if you get my drift............

Right well I do guess you'd like to know the history of things?

You can also check the MP Amber OD hint hint hint

Sorry I cannot give more info on that as it is sensitive

At your service
BJ
Designer of MP Amber OD

harmaes · Post by **harmaes** » 31 Aug 2016, 20:50

Isn't this close in design to the Skreddy P19?

hopdybob · Post by **hopdybob** » 17 Sep 2016, 10:50

Hello out there.
i am somekind of new in this stompbox building and am trying to build this stompbox fromt the following layout.
http://tagboardeffects.blogspot.nl/2016 ... drive.html

somethings seems to go wrong.
it works, but thinking this overdrive will boost the volume level, with volume on max i can get the same volume as when hitting the bypass switch.
it is not going louder
i also can not get a sound like this, a lightly overdrive sound

any ideas?

BJF · Post by **BJF** » 25 Sep 2016, 20:38

Hi there,
You might want to check the last J FET and that it has enough Drain-Source voltage.....

At your service
BJ
BJF Electronics
Sweden

hopdybob · Post by **hopdybob** » 27 Sep 2016, 17:48

BJF wrote:Hi there,
You might want to check the last J FET and that it has enough Drain-Source voltage.....

At your service
BJ
BJF Electronics
Sweden

in this topic
viewtopic.php?f=73&t=27892
another member pointed out that i had put the most right elco 1 uF +/- wrong.

i have corrected this with a new elco but got a kind of sound generator sound that changed using the sustain pot.
also replaced the Q4 but have the same result

BJF · Post by **BJF** » 03 Oct 2016, 02:28

hopdybob wrote:
BJF wrote:Hi there,
You might want to check the last J FET and that it has enough Drain-Source voltage.....

At your service
BJ
BJF Electronics
Sweden
in this topic
viewtopic.php?f=73&t=27892
another member pointed out that i had put the most right elco 1 uF +/- wrong.

i have corrected this with a new elco but got a kind of sound generator sound that changed using the sustain pot.
also replaced the Q4 but have the same result

Hi there,

Well polarized components need to have the correct polarity.

Check that C13 a 100uF/25V cap is present and bypassing the B-tree- if not the circuit will feed back on itself.
Oscillations can also occour via wiring and if so you should be able to move wires to stop oscillation and it's mostly about keeping
all in phase connections seperate.

First thing though when faultfinding a circuit like this is to take the voltages at the transistors

At your service
BJ
BJF Electronics
Sweden

Mad Professor - Amber Drive [traced]