Melxowtone Component Values

[chutneyfarmer]

Heya folks,

Not expecting much luck with this but here it goes. If anyone thinks this is bad form, please let me know but given the limited nature of the pedal, and the builder being M.I.A., I think it should be ok.

I'm looking to build a Melxowtone clone in a mini enclosure and was wondering if someone could open up theirs and check the component values for me? I know, I know it's a simple pedal with hardly any components but I love the sound of it and would like to build an exact clone as opposed to an approximation of one. I also find with simple pedals, slight variations in components can have major affects on the sound.

Any help would be greatly appreciated folks.

Equally, if anyone wants to sell me theirs for a reasonable (i.e. non-exploitative) price, I'd be willing to buy it of course!

[eatyourguitar]

you might like the breadboard versions better than the real thing. you never know until you go.

[chutneyfarmer]

you might like the breadboard versions better than the real thing. you never know until you go.

That's quite true actually, but having the original values would be the best starting point.

[morange]

Use 1M for R1, 47k for R2, and take out R3 (connecting Q1 emitter directly to ground), and I think you're there.

Here's a gut I found:


You can see two 1M resistors, a 47k resistor, and two 100n caps. If the base is biased like in the Electra Distortion (http://en.wikipedia.org/wiki/Bipolar_transistor_biasing#Collector-to-base_bias), then one 1M resistor attaches between the collector and base of the transistor, and the other attaches from the input side of the first capacitor to ground (a resistor to prevent pop when the circuit is switched).

[chutneyfarmer]

Nice one Morange!!! Thanks very much, I really appreciate that. Been wanting one of these for a long long time now

Where did you find that gut shot? Have looked all over the web for info and haven't seen many gut shots.

[morange]

http://ilovefuzz.com/viewtopic.php?f=149&t=25766

So it's a Melx 2. I'm not sure exactly how the reissue is different than the original, besides that it's the same design, with some kind of slight component change. http://www.ilovefuzz.com/viewtopic.php?f=141&t=9067&p=120206&hilit=+melx#p120206


So, here's my educated guess about component values:

R1 might be 2.2M in the original. To me, based on the videos I've watched involving the original and the reissue, the original sounds slightly more compressed, and an R1 value of 2.2M would give a more compressed sound than 1M. So that's what I think changed.

R2 most likely is the same value, 47k. Increasing R2 increases gain, but 47k is about as high as you can go with 3904 transistors before you start losing gain again (not enough current) in my experience. I don't think R2 would be higher than 47k in the original Melxowtone. Something lower, like 10k, might be something to try, but I don't think it's lower in the original.

I think the caps would be the same values, 100n for both. They pretty much pass everything.

The gain of the particular batch of 3904 transistors used has an effect on sound, but I don't think this was changed intentionally.

[chutneyfarmer]

http://ilovefuzz.com/viewtopic.php?f=149&t=25766

So it's a Melx 2. I'm not sure exactly how the reissue is different than the original, besides that it's the same design, with some kind of slight component change. http://www.ilovefuzz.com/viewtopic.php?f=141&t=9067&p=120206&hilit=+melx#p120206


So, here's my educated guess about component values:

R1 might be 2.2M in the original. To me, based on the videos I've watched involving the original and the reissue, the original sounds slightly more compressed, and an R1 value of 2.2M would give a more compressed sound than 1M. So that's what I think changed.

R2 most likely is the same value, 47k. Increasing R2 increases gain, but 47k is about as high as you can go with 3904 transistors before you start losing gain again (not enough current) in my experience. I don't think R2 would be higher than 47k in the original Melxowtone. Something lower, like 10k, might be something to try, but I don't think it's lower in the original.

I think the caps would be the same values, 100n for both. They pretty much pass everything.

The gain of the particular batch of 3904 transistors used has an effect on sound, but I don't think this was changed intentionally.

Managed to dig up a little more info. Think I may have been googling a mis-spelling of the name previously

I think you're spot on with the resistor values! One difference between V1 and V2 I think is to do with the diodes actually. In the Melx2 both diodes, as far as I can see, are identical. In the original they are different. One is similar to the ones in the Melx2 and the other is a black one.

[morange]

One difference between V1 and V2 I think is to do with the diodes actually. In the Melx2 both diodes, as far as I can see, are identical. In the original they are different. One is similar to the ones in the Melx2 and the other is a black one.

I didn't know that. Neato. 1N4001 maybe?

Also relevant, I just saw another, better gut shot of the Melx 2:
http://www.ilovefuzz.com/viewtopic.php?f=151&t=28433

[Dev...in]

I love this pedal, its a great sounding sounding and simple circuit. I was wondering if anyone could describe for me how the diodes are interacting with the transistor and how they affect the sound?

[smallsnd/bigsnd]

the diodes are clipping the signal and introducing distortion. there's way more going on here regarding different diode types, harmonics, loading, etc. but here's a simple image to help you understand what's going on:



here's the schematic for an electra, which is very close to the melx and has some more insight on the role the diodes play.

[Dev...in]

Thank you, that was very helpful! ...are diodes always located just before the output?

[smallsnd/bigsnd]

not necessarily, but often. here's 2 examples --
diodes at output:
DS1


diodes somewhere else:
superfuzz