MUFF Overdrive EH Nano series

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MUFF Overdrive EH Nano series

Postby tubelectron » 01 May 2011, 14:40

Hi All,

Here's more informations about this little cheap, simple but really good sounding pedal : the MUFF Overdrive EH Nano.

Image

I traced the schematic from the double-sided PCB. There is no SMD components in the unit (2011) :

Image

This is the direct descendant of the 1969 MUFF-FUZZ, with the exception of C5 and C6, which were 0µ1 at that time, and of course the RF filters, which didn't existed. The MUFF Overdrive sounds even more mellow for these reasons.

I made some minor modifications, but no component change :

1 - I grounded the metal box. Surprisingly, it was not... It's better for hum protection.

Image

2 - I put a more readable knob with an engraved index, for more easy setting on stage.

Image

A+!

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blackbunny (02 May 2011, 02:28), Dirk_Hendrik (01 May 2011, 20:12), jb351 (01 May 2011, 20:40), lolbou (01 May 2011, 21:39), Nocentelli (01 May 2011, 20:24), raindog (23 Jun 2011, 08:33), rbstep (30 Jun 2011, 21:30), RnFR (23 Jun 2011, 09:12), vax71 (16 Oct 2017, 12:26)
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Re: MUFF Overdrive EH Nano series

Postby euronymous0001 » 01 May 2011, 18:42

:scratch:
what are those black cylinders near the LED?
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Re: MUFF Overdrive EH Nano series

Postby tubelectron » 01 May 2011, 19:33

euronymous0001 wrote::scratch:
what are those black cylinders near the LED?


These are the RF filters labelled FB1 and FB2 on the schematic (ferrite beads). You also find the same in the LPB-1 EH Nano series.

A+!
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Re: MUFF Overdrive EH Nano series

Postby Dirk_Hendrik » 01 May 2011, 20:13

Thanks. Nice schematic "handwriting". Very easy readable :thumbsup
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
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Re: MUFF Overdrive EH Nano series

Postby Hides-His-Eyes » 01 May 2011, 20:28

:o NOT TRUE BYPASS

get the pitchforks chaps
Testing, testing, won too fwee
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Re: MUFF Overdrive EH Nano series

Postby tubelectron » 01 May 2011, 21:37

Hides-His-Eyes wrote::o NOT TRUE BYPASS

get the pitchforks chaps


I confirm that it is TRUE BYPASS : I checked it again to be sure a few minutes ago with my DMM and dummy jacks. When the effect is off, the FX input and output are both disconnected from the signal path : that's true by-pass. So I guessed for the rest of the switching to be somewhat similar to my schematic.

But my guess was inaccurate : my schematic is effectively wrong about the switching - I hate those double-sided PCB painful to trace for declining sight people !

Rectification :
The output switching is correct.
The input switching is : ON = FX input to input jack, OFF = FX input to GND (FX muting).
The led switching cuts the GND to the led + R8 when OFF.


Good evening to "les garçons de fourches à foin",

Cheers,

A+!
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Re: MUFF Overdrive EH Nano series

Postby Nocentelli » 01 May 2011, 21:59

So are you saying the ferrite beads and 100p caps re NOT permanently in the signal path? I had a nano LPB-1 for a while, and I read up about it on some diyfx blog that was adamant these were permanently connected (presumably because the case is not grounded).
mmolteratx wrote:absolutely zero commercial use allowed. If I find anyone selling these, I'll fly to your house and kick you in the nads. And you may or may not find yourself in trouble.
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Re: MUFF Overdrive EH Nano series

Postby tubelectron » 02 May 2011, 08:05

Nocentelli wrote:So are you saying the ferrite beads and 100p caps re NOT permanently in the signal path? I had a nano LPB-1 for a while, and I read up about it on some diyfx blog that was adamant these were permanently connected (presumably because the case is not grounded).


Yes, that's it - I confirm that these RF filters are permanently connected into the signal path.

So you have a permanent "taming" cap total value of 200p to GND (I checked it it with my FL-87V), to be compared with the 1000p to 1500p total capacity that often exists in the signal path (2 cables, 2-3 effects, that's what I measure usually). So you would have a little probable loss in the high treble range when FX in disengaged - I checked and found it negligible, almost in my setup.

Moreover, I read again the EH MUFF Overdrive small notice given with the unit :

"FOOTSWITCH - Selects whether the MUFF Overdrive is engaged or in True Bypass. The corresponding LED will be lit when the pedal is engaged, and dark when True Bypassed"... Nearly true, then...

So if we accept to discard the 200p taming capacity, the effect is checked as a True Bypass, as when the effect is disengaged, the IN and OUT of the FX have no more connection with the signal path...

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Re: MUFF Overdrive EH Nano series

Postby Charley Umbria » 22 Jun 2011, 22:37

Hmmm, interesting about the "true bypass". Nice sleuthing!

I'd guess that the ferrite beads don't have any detrimental effect on tone. But, those caps... What do you think would happen if one were to just disconnect the taming caps from the circuit? Snip a leg (or two), perhaps?

I also wondered if you noticed any discernible improvement after your grounding mod. Thanks!
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Re: MUFF Overdrive EH Nano series

Postby tubelectron » 30 Jun 2011, 20:48

But, those caps... What do you think would happen if one were to just disconnect the taming caps from the circuit? Snip a leg (or two), perhaps?


You would probably have a little more treble, if any - I did not tried it, as the sound suits me as is...

I also wondered if you noticed any discernible improvement after your grounding mod


At high playing volume, the unit is more quiet. At lower levels, there is no more hum when you touch the box with the hand. You may not experiment this improvement as tremendous, but non-grouding that box was an aberration for me !

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Re: MUFF Overdrive EH Nano series

Postby greigoroth » 01 Sep 2012, 13:16

Sorry for the necro bump - how do you get the pcb out of the enclosure in these nano-style housings?

I was reluctant to do anything wild, but it looked like if you took the knob off and pushed hard enough it would drop right out? I can post pics if necessary.

Cheers!
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Re: MUFF Overdrive EH Nano series

Postby allesz » 01 Sep 2012, 23:34

I had a poket metal muff for some time (not bad at all.... but I like to change).
To unbox it you have to remove the knob (I used a small flat screw driver) and unscrew the pot, jacks and the footswitch.
Then gently extract all the pakage from the box; the 9v jack is the hardest part, you will have to tilt a little the pcb in order to free this part of the circuit.

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Re: MUFF Overdrive EH Nano series

Postby Andrew1591 » 09 Jan 2013, 22:53

Is there anyway to get more midrange out of this pedal, I know it sounds cliche to add mods to the muff sound but I keep getting "lost" in the mix when ever I step on this pedal
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Re: MUFF Overdrive EH Nano series

Postby allesz » 10 Jan 2013, 12:31

Andrew1591 wrote:Is there anyway to get more midrange out of this pedal, I know it sounds cliche to add mods to the muff sound but I keep getting "lost" in the mix when ever I step on this pedal


Maybe try soldering a cap in parallel to R6.... try 100nF, 220nF, 270, 330.... don't put it bigger than 1uF because in this case you will get more gain, but on the wole bandwith of the guitar signal, loosing the mid boost effect.
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Re: MUFF Overdrive EH Nano series

Postby vax71 » 16 Oct 2017, 12:25

I read somewhere Q2 is soldered on the wrong side of the PCB: you can see its printing is mirrored on the up side. The transistor just can not do its job this way! It should be on the bottom side. :shock:
I didn't try yet (need to change some parts) but it makes sense for me.
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