EHX - Satisfaction Fuzz

boblob · Post by **boblob** » 01 Apr 2014, 20:37

Quick search tells me there's nothing on these yet...

Although it's difficult to tell from a yt clip, this actually sounds reasonably like an FZ-1A:

A couple of gutshots have surfaced, and to me looking very Bosstone sans clipping diodes (which you can add yourself) and a couple of free pads for a more bass-friendly response. Seems Jack Orman independently concurs from the youtube comments...

Whatever, it sounds pretty good to me and cheap enough to snag out of curiousity.

VicoVibe · Post by **VicoVibe** » 04 Apr 2014, 12:02

The clipping diodes are under the board.

mirosol · Post by **mirosol** » 14 Apr 2014, 17:31

There are no clipping diodes under the board. Just empty pads.

This arrived today and i ripped it open as soon as i got it. The places for C7 and the clippers are empty, but they do have a silkscreened "+bass" and diode markings on them. Since the circuit is rather small i traced it. It became evident that it is nothing more than Jordan Bosstone without the clippers and with couple of different cap values. Some caps didn't have any markings on them and i didn't feel like desoldering these SMD bits, so i simply measured the caps and rounded the values out of those readings. So some of those may be incorrect, but it is still a Bosstone.

There are couple of quite interesting things about this. Like for instance, there are two resistors marked as R6 on the silk screened markings. Other is 1M pulldown (in parallel with Attack pot.. why?...) and the other is 1K for the indicator LED. The empty pads are also a weird thing to see. Like this unit is meant to sound bad, but on the silver lining is that you can make it a Bosstone yourlself?

I istalled a 22n cap for C7 on my unit. Huge and instant improvement. Tried on a couple of different pairs of clippers too, but decided to leave the diodes out.In essence, one could buy one of these for cheap, add the diodes, add the cap and swap the input cap for 10n. Probably one of the cheapest ways to get yourself a Bosstone. I'd be surprised if someone isn't selling a Bosstone mod for Satisfaction already...

Anyway. There you go. I did drew up stripboard layout too.

EHX Satisfaction Fuzz BOM:
Q1 - KSP2222A
Q2 - 2N3906
D1 - S1G
D2-D3 - Not mounted
FB1

P1 Attack - A100K
P2 Volume - A100K

C1 - 22n
C2 - 22n*
C3 - 1n5*
C4 - 4n7*
C5 - (no measurement)
C6 - 100µ/25V
C7 - Not mounted
(* measured while mounted - these count as guessed values)

R1 - 5603 - 560k
R2 - 5603 - 560k
R3 - 1503 - 150k
R4 - 1802 - 18k
R5 - 1802 - 18k
R6 (Input) - 1004 - 1M
R6 (LED) - 1002 - 1k

boblob · Post by **boblob** » 19 Apr 2014, 16:11

Cool - that's that mystery over.

Minor thing, but there's a ferrite bead at the +9V - that will help with RFI.

The 1M resistor will change the sweep of the Attack pot maybe give it a more intuitive feel. Bosstones have a tendency to oscillate with the Attack down low - I had thought that was for setting the minimum Attack before I saw your schematic. Seems not.

Changing C2 up to 10n will cut some woof and give it a bit of a cocked wah thing. Surface mount though, so a bit of a pain to change.

mirosol · Post by **mirosol** » 20 Apr 2014, 07:40

I simply omitted the bead as i don't think many DIY builders willl include it (plus i didn't spot the image on the software :) - Yup. Call me lazy). I also omitted the bypass switching and the LED. So yeah. The schematic is not perfect.

The 1M in parallel with 50k pot makes a little difference. On mathematical point, the value becomes 47,6k and the effect on the taper is also minute. It should rather make the taper "super log", which leaves more of the sweep on the oscillating range. If the 1M was placed between lugs 2 & 3, then it could contribute to making the taper less prone to all the great weirdness that happens at the minimum settings of the attack pot on Bosstone circuit. However, this circuit doesn't seen to do that on minimum settings. My guess is that the cap value changes are behind that. Maybe the ferrite bead is another thing affecting the non-weirdness.

Someone on our blog built the stripboard layout, so that can be considered as verified. The transistor name has an error (5xAs), but i think most of you can live with that..

boblob · Post by **boblob** » 20 Apr 2014, 13:00

It'll take a little off the top end (1M || 100K ~ 91K) - maybe that helps tame it at full Attack.

Using 3x 10n in place of the 3x 22n in the regular Bosstone kills the oscillation (I think one of the many Nashville variants uses 10s). The 1.5n on Q2 is much bigger than the usual 51pF - I guess that would also tame it. I don't know about measuring caps in circuit, though - how off is that likely to be? Time to get the breadboard out and see...

It looks very much like EHX expect people to mod these. Good for them. Korg have been doing similar things for a few years now and it pays off with lots of free internet buzz.

Anyways - thanks for taking the time to trace this, man!

mirosol · Post by **mirosol** » 20 Apr 2014, 16:14

You're correct with ~91K. I should not write answers to posts before i get my morning coffee. For some stupid reason i remembered the attack to be 50K :)

Measuring on-circuit caps can result in values that are way off, but since the dude who verified the layout didn't think the sound was off, i'll accept the measurement for now.

gemather · Post by **gemather** » 10 Apr 2016, 18:50

My Bosstone clone is a Fuzz with a treble boosting effect.
Realy nice in front of my Big Muff. Realy doomy together.
I like any treble booster in front of my Big Muff, too.
But for most of my playing i like extra fuzz into the Big Muff.

The EHX Satisfaction has a similar effect with 8,2nF in C7.

I like to note, that 10nF or 8,2nF are more Bosstone a like.

I installed 2 diodes and removed them later. The Satisfaction is better to handle without them.
I think the bosstone has 2 diodes installed and my Bosstone clone has more(too much) gain.

mattmayhem · Post by **mattmayhem** » 27 Mar 2020, 20:53

I think two cap values in the above info are wrong (or maybe c3 and c4 are just mislabeled on the board). The build above is too dark when compared with the EHX pedal. C4 should be 1.5nf. I replaced C3 with a 250pf (as close as I had laying around to the 47pf per the Bosstone schematic), but not sure if that cap value really impacts the tone as much. Anyway, after these changes, my build sounds pretty much exactly like my stock EHX. Just an FYI for any builders looking for info on this one. Above layout still sounded great, just darker than the EHX.

BMS1971 · Post by **BMS1971** » 04 May 2023, 07:41

Any idea what they did with the 4 knobs version?
Ben

B3ar · Post by **B3ar** » 04 May 2023, 21:00

Chances are the bias knob is a riff on a Trombetta design, as found in his J Rockett collab, the WTF: viewtopic.php?t=25324. From the demos, I’m not hearing the full trombone sag thing, so I would guess it’s not a lot of resistance added.

For the rest, just some guesses. The fat switch is probably about input caps, with a bigger value for the “fat” mode. Tone control could be a bunch of things. For easy DIY I might try at SuperFuzz-based things that swap the switch for a pot to balance between the two caps.

I would love to see guts to see how far the Deluxe can go into the full Trombetta-ish insanity.

EHX - Satisfaction Fuzz [schematic]