Do cables matter with a Fuzz Face? Tests.

[freefrog]

I share below a few data that I had in my mind while replying to a recent topic.

I just needed to edit the related screenshots (expurgated below of some essential data for questions of intellectual property; thx for your understanding about that).


GEAR USED:

-Gibson Flying V with low output P.A.F. clones, uncovered. Resistance: 7.8k & 7.2k. Inductance: 4.2H & 3.6H. UOA5 mags, 500k volume pot, 250k no load tone.

-Fuzz Face with low hfe NOS (silicon) transistors.


-Various cables:

*two 10ft Sommer “Black Zilk”, ultra low capacitance (each measuring a stray capacitance of 185pF, jack plugs included);

*one single 10ft coily cord, measuring a stray cap of 1nF (=1000pF. It’s the average value of a straight 20ft cable and it’s logical, since a 10ft coily cable includes roughly 6m of cable coiled on itself).

*one single 60ft straight cable, measuring the expected parasitic capacitance: a whooping 3.2nF (=3200pF). It’s almost ten times the overall cap of the two Sommer cables altogether.


TESTING RIG:

-an ultra low impedance air coil has been used to excite the neck PU.

-this air coil has sent a swept mono signal to the pickup then through the Fuzz Face (enabled), itself located between two of the cables mentioned above. Final host: a 1M input.

-the frequency response and THD measured in each case has been captured thx to the dedicated testing hardware and software devices (not to be revealed here).



WHAT THE SCREENSHOTS WILL SHOW:

-upper horizontal lines: frequency response.

-lower horizontal lines: THD.

-red lines = the Fuzz Face before an average BUFFER… Blue line = the same pedal plugged directly to a 1M input, without buffer.



The buffer increases the distortion in the low frequencies and makes this distortion bassier, whatever is the measured frequency response. Conversely, any reduced THD in the bass and low mid frequencies reveals in which proportions the FF is thin sounding (and edgy/ harsh, as if a series cap was in the circuit)...


The cables change this THD as well as the frequency response as shown below…

https://imgur.com/IHRwc3S

https://imgur.com/iSW5ZDS

https://imgur.com/Hv8IEF1

https://imgur.com/BHzdMVu

https://imgur.com/d9eGFW5

 

[freefrog]

EFFECT ON THE PERCEIVED ‘’COMPRESSION’’:

https://imgur.com/1pZVS4f

It's an impulse response measurement.

Red line = Fuzz Face before buffer. Blue line = Fuzz Face between coil cord and long (hi cap) straight cable. The attack is squashed and slowed down in such a proportion that the testing rig is fooled by the difference… that’s why the blue line is before the red one (the slowest before the fastest).

Sonically, the low output P.A.F. clone is therefore heard as smoothly compressed with the highest capacitance.


FWIW.

Sorry for any possible error or omission. I post all this stuff on a hurry, just to share. EDIT - There was a mistake in a sum up of all screenshots so I've cancelled it. :-/


NOTE – There’s many critical parameters with this falsely simple circuit named Fuzz Face. Cable capacitance is only one of them… but not necessarily a negligible one, I hope this statement to be clear now.

 

[freefrog]

But what about the SOUND?

Inspired by a recent thread, I've plugged my brightest sounding LP in an Orange AD30 digital clone (‘Line6 "Citrus’’) + a virtual 4x12 cab with V30’s miked by a virtual SM57.

All controls were full up, except the gain at first BUT I've tried with the gain maxed out too.

Between the LP and amp input, I've plugged the forementioned Fuzz Face.

Firstly, I've used the two ultra low capacitance 10' cables.

Then I've plugged the LP through the 60ft cable and the FF to the amp sim input through the short coily cord.

I’ve played strictly the same abstract from “Foxy Lady” in both cases.

As it's easier to post a pic than a sound sample, I share below the related screenshot, showing the frequencies generated.

Blue line = high capacitance cables.

Orange line = low capacitance cables.

https://imgur.com/YPmNvGi

It should suggest what I've heard: with a tad less mids but also with +3dB to +6dB above 3khz, the sound was painfully edgier in the recording with short low capacitance cables.

The second recording, with the longer cables, was a tad beefier in the mids and noticeably darker, thx to the softened high range above 2.5khz. As explained somewhere above, increased cable capacitance had also an effect on the perceived “compression”. Globally, the attack was softer.

There’s a consistency between this test and my expectations, themselves in phase with my posts above.

It doesn’t imply that other LP/ FF/ Amp would sound the same / react in the same way for another player: there’s so many variables that I consider to have rambled about only a tiny part of the whole pic… but again, what I’m talking about is not necessarily negligible. YMMV.

 

[Alligatorbling]

Everything is a variable with fuzz. Even the color shirt you have on.

 

[freefrog]

Damn, I've forgotten to check f I had the same shirt during all these tests!

Other conditions were identical (except my underwear).

Now, there's some "tendencies" that I've tried to make obvious but that I've forgotten to sum up, so let's go:

- more length of cable = more capacitance, typically;

- this parameter affects the tone (reason why tone controls are based on capacitors, usually);

-with a Fuzz Face more than with some other effects, the same parameter has a noticeable influence.

The cable plugged after a FF, especially, allows to "tune it": longer cable = more capacitance = bassier spectrum & distortion + more "compressed" attack.

As said elsewhere, a tiny cheapo cap of the proper value can be put between hot and ground of the volume control if not the output jack to emulate this effect.

That's all folks.


EDIT - Actually, all was not said. Below is the same thing than in post 3, BUT the blue line sums up a recording done with the cables in reverse order: 10ft / 1nF coil cable from guitar to FF, THEN 60ft / 3.2nF straight cable from FF to amp sim input.

It should make even clearer the influence of the cable "after" the FF: it's really a kind of external control for it (but could be replaced by a capacitor from hot to ground IN the pedal: a 2.7nF component before an average 10ft cable between pedal and amp would alter the sound as shown below)...

https://imgur.com/HbMPsZX

EDIT, bis - the presence of stray capacitance at the output actually affects many drive FX's.
Below is for instance the electrically induced response of a Big Muff (RH RI) through a short patch cable then through a high capacitance one (a coily cable, whose effect is shown in green).

 

[Brek]

Sir, I salute you for your methodology. great job. i still haven't done traces of my various mods. My work area is a mess and not conducive to doing so at mo.

 

[freefrog]

Footnote: I've tested (again) Line6 fuzz clones from various generations. It definitively seems that Line6 has modeled the Fuzz Face through a 1nF cable @ the output. For the record, it"s more or less the typical capacitance of an average 20ft / 6m guitar cable.

Not surprising to me: all the tests done here on a Line6 Variax suggest that Line6 engineers modeled vintage guitars through a 1nF cable as well... this value is realistic compared to what many guitarists use and... it's handy to make digital modelling more "analog" sounding (or to hide some related artifacts).

I don't remember if Boss/Vox/Zoom did the same with their FF digital emulations. I'll have to dig in my archives, if time permits...