Differential Distortion build report

[LucifersTrip]

I finally finished tweaking this oddball. I rarely work with silicon or modern effects, but this looked interesting.


I read a bit about it beforehand and the general comments were right on...the output is low....insanely low...unusably low.

I slowly lowered the 100K (between the 2 emitters) until I reached a good volume. Unfortunately, when the volume is raised, the bass is also increased. I slowly lowered the in/out caps to compensate for that, and decided on .022uF (a close 2nd was .033uF).

It needed a bit more juice so I experimented with all resistors. Increasing Q3's collector to 3K gave me more volume and what seemed like a bit more sustain on the higher strings. Take your time adjusting that one. If you go too high, it gets too boomy again.

I also increased Q1's collector resistor to give it a bit more oomph. I increased it slightly while hitting the high strings and stopped when they sustained the best. If I went over 150K, the tone went downhill.

Lastly, I found that increasing the 1M pullup on Q1's base actually smoothens out the grungy tone a bit and removes a little bass....It actually starts moving away from a distortion and get a little more fuzz.  It works as a good drive. Increase beyond 100K and you'll get a significant thinning and volume drop.

Here's my first tweaked version with a good sound, minus the drive pot:


Now that I had a good basis, I decided to screw with the transistors. Decreasing the hfe of Q1-Q3 did what I expected. It became more dirty and lower gain sounding. For me this needed the opposite.

The highest gain silicons I have are MPSA18 NPN's with gains of around 800, so I decided to switch to + ground. Lo and behold they gave me the extra that I wanted and produced a  smoother and a bit fuzzier tone. I tried various Q1's and surprisingly ones with gains of only ~200-250 sounded better than the ones I tried in the 300-400 range. Unfortunately, I don't have any higher gain PNP's to try.

I tried various volume pots and even with a 1M I lost a little oomph and bass, so I increased Q3's collector resistor a bit more and wound up with the final (probably) version.

[LucifersTrip]

not a single person tried this one recently?

[DavenPaget]

Hey luci , how about trying out a "DIY" darlington 
( Made from 2 x 2N5088 no less . )

[LucifersTrip]

Hey luci , how about trying out a "DIY" darlington 
( Made from 2 x 2N5088 no less . )

I love darlingtons, especially since I can make higher gain germanium fuzzes !   

...recently posted about this which I helped a friend build:
http://www.diystompboxes.com/smfforum/index.php?topic=94895.0

but the best I just finished is this:
http://www.luciferstrip.com/fuzz/buzzaround-final.jpg

The differential thing is a whole different ball game....very few fuzzes made that way