Seymour Duncan Tweak Fuzz EJ Mods

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Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 18 Mar 2016, 05:35

I'm a big fan of this much maligned pedal. I have 3 of them.
They sound stellar into a MIAB type pedal in front of either my Blues Jr or Hot Rod Deluxe.


One is rehoused into a Small Bear 125-B enclosure without a switch so it would fit better onto my main board with a switcher.

(purple box, upper-right)
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One will be getting the full-on EJ FF treatment with TI BC183 & Fairchild BC183C transistors. I'll also be bringing the high-gain transistor collector bias trim pot out to an external knob for easy adjustment. I really like the idea of the big EJ silicon FF tone but with the options of a pre-gain bass roll-off Tweak knob. Kinda surprised you don't see something like this on more Fuzz boxes. Makes for a much more versatile Fuzz. I can't wait for my BC's to arrive to get started.

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The 3rd I plan to keep stock except for the volume boost mod (R4, R5). Though...I have thought about installing a 2nd Tweak knob and adding another footswitch to allow easy selection of 2 different Tweak knob settings.

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Has anyone else modded their Tweak Fuzz? Just looking for additional ideas.
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby Nocentelli » 18 Mar 2016, 06:19

Since it is a fuzz face derivative with an input cap selector, any standard fuzzface mods will be applicable: Replacing the 100k Q2e->Q1b feedback resistor with a much smaller fixed resistor and a much larger pot in series (e.g. 15k + 500k pot) gives an large variety of new sounds from tighter and more responsive at lower values, to super saturated and spongy at higher values (woolly mammoth "pinch" mod).
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 18 Mar 2016, 06:57

Nocentelli wrote:Since it is a fuzz face derivative with an input cap selector, any standard fuzzface mods will be applicable: Replacing the 100k Q2e->Q1b feedback resistor with a much smaller fixed resistor and a much larger pot in series (e.g. 15k + 500k pot) gives an large variety of new sounds from tighter and more responsive at lower values, to super saturated and spongy at higher values (woolly mammoth "pinch" mod).


Thanks! I didn't realize the Woolly Mammoth (and Mastotron) were so close to the FF in basic topology. The Pinch mod looks like an interesting thing to try.
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby B3ar » 29 Mar 2016, 12:52

For R4/R5, are you doing the 1K/18k Mayer/Hendrix mod? Because it alters my answer's starting ranges. I'd think about a bias tweak knob. For the stock 8K2, a 10k trimmer for R5 gets you into normal biasing range to overbiasing Q2 at low ranges (TF's "Q1" on the board), with 25k giving you the range to under bias/starve at high ranges. For 18k, I'd start with 25k for over, 50k for under ranges. Obviously, the high value trims should give you all ranges, but the smaller values will give you finer precision on dialing it in. Experiment with R5 values, maybe duplicate with fixed resistors, and put 'em on a rotary, or if you have a favorite two that you want to have as stompable, put them on a stomp, with or without LED.

How the heck are you drilling these? Mine are built like bunkers.
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 31 Mar 2016, 15:58

I'm not even aware of that mod...

No, I did the mod that has been floating around the internet for years.
R4 = 8.2k
R5 = Short
Dramatically increases the output, though it may be a bit overkill.

The EJ FF is setup like this:
R4 = 6.04k
R5 = 5k Trimpot

This seems more reasonable for the output level and gives a good range of bias adjustment.

I haven't drilled one of the enclosures out yet, but I will soon. I have access to a drill press at work so it shouldn't be a problem.
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 01 Apr 2016, 20:28

Painted yesterday.

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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 05 Apr 2016, 16:49

Double-Tweak-Mod in process...

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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby B3ar » 06 Apr 2016, 01:29

Nice. Enough depth at the front of the enclosure for standard blue 3pdt stomp switches, or did you need to go with a lower profile switch?
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 06 Apr 2016, 04:08

Plenty of room for the blue 3PDT switches.

I finished up phase 1 of the double-tweak-mod tonight.
Works great and adds even more flexibility to an already cool pedal.

I'll probably use some of those unused switch contacts to switch between a couple of LEDs to show which Tweak knob is selected.

Pay no attention to the rotated switch PCB... :oops:

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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 10 Apr 2016, 16:32

Nocentelli wrote:Since it is a fuzz face derivative with an input cap selector, any standard fuzzface mods will be applicable: Replacing the 100k Q2e->Q1b feedback resistor with a much smaller fixed resistor and a much larger pot in series (e.g. 15k + 500k pot) gives an large variety of new sounds from tighter and more responsive at lower values, to super saturated and spongy at higher values (woolly mammoth "pinch" mod).


I tried the "pinch" mod the other day. I left the stock 100k feedback resistor in there and added a 250k pot in series. I was baffled that I couldn't hear ANY difference from one extreme of the pot to the other. So I removed it. I figured 350k in the feedback path would be a really obvious change.
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby Nocentelli » 10 Apr 2016, 21:36

I love the tweaked tweak fuzz.

stilwel wrote: I was baffled that I couldn't hear ANY difference from one extreme of the pot to the other. So I removed it. I figured 350k in the feedback path would be a really obvious change.


Hmm. I'm surprised you didn't get any noticeable change.... the effect is dependent in the setting of the gain pot, maybe it's a bit more obvious from 20k to 150k and with the gain well up
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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 18 May 2016, 03:30

Last night I added an LED so I can tell when the lower Tweak knob is selected.

Image


I'm like a crazy cat lady, but instead of cats it's Tweak Fuzz units. The gold one is an EJ FF (BC183) with an external bias pot. The left footswitch is bypass and the right switch will select between 2 preset input caps. I need to come up with a plan for the lower-right unit.

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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby stilwel » 31 May 2016, 03:43

Quick clip of the Tweak Fuzz with BC183 transistors.

Strat -> Fuzz -> SL Drive -> MS-70CDR -> Hot Rod Deluxe (V-type speaker)


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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby snofla1900 » 31 May 2016, 09:15

Thnks for the (short) clip. I think it sounds really good. Especially in the higher regions of the guitar.

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Re: Seymour Duncan Tweak Fuzz EJ Mods

Postby fusionid » 17 Dec 2017, 22:37

What resistor is the traditional bias resistor on the layout?

Thanks
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