Favorite mods for Dunlop JDF2 FuzzFace?

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
Post Reply
User avatar
GilmourD
Information
Posts: 8
Joined: 31 Jul 2010, 07:13
Been thanked: 2 times

Post by GilmourD »

So, about a year ago I bought the guts of a JDF2 off eBay. I think it's the older version as it has the transistors marked DMI158 rather than the reissue NKTs. It works just fine (I was actually goofing around with it on Sunday) but it's a bit wooly and gets a touch dark when I roll the volume down.

So, before I order an enclosure to put it in I was figuring I'd like to do some simple mods to it to maybe improve the clarity and versatility, which might change how many knobs are on the enclosure I order.

So, what do you guys like to do to these things? Transistor changes, I imagine, but anything else? Favorite transistors that won't cost me one of my children? Whatcha think?

User avatar
soulsonic
Old Solderhand
Information
Posts: 3828
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Stopped using amps mostly...
Completed builds: too many!
Location: Homer, NY
Has thanked: 134 times
Been thanked: 364 times
Contact:

Post by soulsonic »

I replaced the input cap on mine with a 1uF film cap. I think this tightened it up in a good way and made it sound a bit more "clear". I think that's all I did to it. Playing with different input cap values is a quick and easy FF mod.
Maybe put several different values on a rotary switch?
Another thing I like is how a Rangemaster sounds boosting the front of it. I combined a Rangemaster with switchable input caps with a fairly stock FF together in one circuit and got the first version of my Shizzle fuzz.
BTW, there are many fuzzes out there, both vintage and contemporary, that are variations of the whole "booster in front of fuzz face" idea. Lots of fun to be had.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
polifemo
Breadboard Brother
Information
Posts: 137
Joined: 09 Nov 2007, 21:42
Location: Stockholm, Sweden.
Has thanked: 3 times
Been thanked: 4 times

Post by polifemo »

I know that this is an old thread, but here we go (might help someone):

Swapping C5/6.8nF for a 220pF cap and lowering C3/2.2uF to 0.47uF will do what you're asking for, and they are very easy mods to do!

Tweaking TP2 can tighten or fatten the pedal and is worth experimenting with.
Also make sure that the bias isn't set too low.

User avatar
nooneknows
Resistor Ronker
Information
Posts: 323
Joined: 26 Mar 2008, 21:53
Has thanked: 48 times
Been thanked: 10 times

Post by nooneknows »

Imho there are 3 main points in every fuzz face build, using JD2F2 schematics they are:

C3 - lowering it to 1uF (film) or 0.47uf the sound results less boomy, more open, since less bass hit the input of the first stage
C2 - depending on versions it seems that sometimes you can find a 0.1uF for output cap, that's somewhat big, early 60s versions have 0.01 uF , so 0.01 or 0.047uF it could be useful to open the sound
R2/R3 - playing with them can cure the common FF low output volume syndrome, using 2.2K instead of 680R and 6.8K instead of 8.2K mantains more or less the same bias but with a louder voice.

a more aggressive mod would be fixing the gain to max with a fixed resistor and using the free hole to put a bias pot for interesting spitting and snorting kind of sound, but that's not my cup of tea

User avatar
polifemo
Breadboard Brother
Information
Posts: 137
Joined: 09 Nov 2007, 21:42
Location: Stockholm, Sweden.
Has thanked: 3 times
Been thanked: 4 times

Post by polifemo »

In my opinion this dark sounding fuzz needs to be ran with the volume control wide open in order to get as much high end as possible out of it. (Lowering the pedals volume below "7-8" results in a considerable loss of high end)

IMHO the best way to get a good sound out of a Fuzz Face is: To run the volume on the pedal on 10, the fuzz between 7-8 and running it into a good tube amp that's breaking up slightly.

The 470r "output resistor" is, once again IMHO, not a design flaw but a well thought out part of the original design in order to prevent the germanium Fuzz Face from sounding too dark.

So, I soldered a 1.8k resistor in parallel with the 680r resistor to get closer to the 470r (I ended up at 483R) in order to being able to run the volume on full without having too much of a bump in volume when engaging the pedal.
Might try a 1.5k resistor as the pedal still is a tiny bit too loud.

My way of checking this is: To run the volume on my Strat on 10 without the FF engaged, I then roll down the guitars volume to 6 (no treble bleed!) and engage the pedal.
The sound I get should now be quite similar to the sound of the amp+guitar on 10, only slightly louder and usually (if it's a good FF) with more sparkle in the high end. (The key for getting maximum sparkle is to have the volume on the fuzz dimed)
With the Strat's volume on 8 I get a distorted rhythm tone and with the guitar's volume on 9-10 I get various degrees of fuzz tone.

All this of course depends on how much the amp is compressing.

Post Reply