Questions about bringing a Guvnor to another pedal's specs (crunchy stuff)

[pott]

...yes... you get what I mean. Anyway... there are some modifications to be done in the power supply. Would these exist because of the different requirements between the LF833 and TL072? Should I do them anyway?
The input section of both pedals are also different and can't be easily modded to each other's specs. I heard some people on here did the mods, how did you guys end up doing it, if I may ask?

Thanks a lot if you can help!

[slacker]

Have you got a schematic for the actual Guvnor you're using? I've only seen the ggg version and on that most of it is virtually the same as "the other pedal" if you're still talking about the same one.

[wampcat1]

what other pedal are you talking about?

[markm]

what other pedal are you talking about?

Crunch Box.

[wampcat1]

MI audio crunchbox? I didn't realize it was a guv'nor circuit.
Not that that is a big deal, just didn't know.

kinda hard to help the OP though without schems for both.
bw

[audioguy]

I read that you can get some insane crunch and gain from the Guv with just a few modifications... but I cant find the thread.

[wampcat1]

OH! That's a different story entirely.
http://www.indyguitarist.com/schematics/marshall%20fx/marshall%20guvnor.gif

c1: .47uf
r1: 470 ohm
r6: 1m
change gain pot to 250k or 500k
remove clipping leds, insert 1n4148 in one spot, and combo of 1n4148 + 1n4148 in the other spot.

There...probably has so much gain it will turn to mush!
If it squeels, reduce c1 and r1 accordingly (use jack ormans's freq filter calculator), and/or reduce r6.

If you want it to clean up better, reduce r6 as much as possible, and do the mods as mentioned on the first opamp.

Hope that helps!

bw

[audioguy]

Cool, thanks!

[stm]

The stock Guv'nor has a combined gain of over 3000 times (70 dB).  The "other" pedal has a combined gain of 10000 times (80 dB).  Wampcat's mod with a 250k gain pot would produce a combined gain in excess of 25000 times (88 dB).

Question:  Is it really necessary to have such humongous gain amounts?  (please don't give "clever" answers like "you can never have too much gain!"  )

In my own experience, I've found that gains around 3000 times are the practical limit due to background hiss, excess of hum and squealing when the guitar faces the speaker and/or the volume is cranked up.  I would like someone to confirm that the Guv'nor really needs more gain, or that the "other" pedal is actually usable with its gain dimed.

On another line of thought, this other pedal is nothing but a mildly modded and simplified Guv'nor:

With respect to the two first gain stages, main differences here are a 1nF cap to ground at the input, probably precluding radio stations to be picked up and maybe some slight harshness reduction, and a different opamp which apparently has better clipping characteristics sound-wise.  Other component changes just increase maximum available gain by 10 dB.

Then, the Guv'nor's tonestack has been greatly simplified from a three-knob bass-mid-treble design to a simpler 1-1/2 knob design.  I mean 1-1/2 because on the outside you have a "Tone" knob and in the inside there is a trimpot to set the balance between bass and treble frequencies (at least on the newer versions).  So, why would anybody already having a functional and flexible three-knob tonestack would want to blindly castrate it into a one knob design?  The only rational explanation would be that a side-by-side comparison between those two pedals show that the simpler tonestack produces a particular sound that cannot be produced with the three-knob design, which is also more desired than the sounds you can get with the three-knob tonestack.

Has anybody done such a comparison?  Just food for thought.

[wampcat1]

good points stm...
Imo, you can't have too much gain


Just kidding ya!! 

Seriously, I've had requests to do wacky stuff like that.. some people just want a pedal that is foolproof and easy to figure out. I built one a pedal for a guy recently that is nothing but a gain knob...the volume is on a trim pot inside...he said he just likes the simplicity.

I myself, like OPTIONS.

bw

[powerplayj]

As far as usable gain, I'd say the CB can go to 1:00 on the gain pot and possibly to 3:00 assuming you set the tone pot at 2:00 or further clockwise to increase the higher frequency response.  Also, for reference, like some other circuits you lose volume with the gain at a mininum and start getting usable volume with gain at 9:00.  Note that the usable gain is already enough for Trower / ZZ Top tones!!!  It is still my favorite pedal for getting into Marshall high gain territory without the mush. 

[slacker]

I would like someone to confirm that the Guv'nor really needs more gain, or that the "other" pedal is actually usable with its gain dimed.

I can't comment on whether or not the Guvnor needs more gain, but I've built "the other" pedal and it's perfectly usable dimed. Admitidly I used a TS272 CMOS opamp and left out the LED clippers, but even with the clippers in it was fine. I guess that's because of the amount of high and low end filtering in the pedal, especially the classic TS bass rolloff of 720Hz, stops things getting too out of hand.

[powerplayj]

I would like someone to confirm that the Guv'nor really needs more gain, or that the "other" pedal is actually usable with its gain dimed.

I can't comment on whether or not the Guvnor needs more gain, but I've built "the other" pedal and it's perfectly usable dimed.

When dimed it wasn't unusable for me, but it felt more compressed as you approached 3/4 and beyond.  I still want to try that IC that you used.

[stm]

Seriously, I've had requests to do wacky stuff like that.. some people
just want a pedal that is foolproof and easy to figure out. I built one a
pedal for a guy recently that is nothing but a gain knob...the volume is
on a trim pot inside...he said he just likes the simplicity.

I myself, like OPTIONS.

Yes, personally I also prefer to have more rather than less options.

I can understand that a person who gigs often might take advantage of a
pedal tailored for his/her specific preference and gear in order to make
its live use foolproof, or simply because someone is interested in a
particular target sound from the pedal.  On the other hand, for studio use
or for a commercial pedal I prefer more flexibility.

In particular, a pedal with a single tone knob is unlikely to work that
well for a broad spectrum of users, considering the different pickups
(single v/s humbucker, quiet v/s hot, active v/s passive), different amps
(valve v/s solid state in the power and/or rectifier sections), different
cabinet configurations (4x10 openback v/s 4x12 closed back v/s single
speaker v/s dual speakers), and different speaker voicings (magnet
material, cone stiffness, suspension, coil, etc).

The above may sound contradictory to the common knowledge, since it seems
that the de-facto standard for fuzzes, distortions and overdrives is a
single tone knob--of course there are pedals with two, three and even four
tone knobs, however I don't think I'm wrong if I say nearly 50% of gain
pedals have a single tone knob (counting DIY designs out there as well).

Where am I heading with this?  My point is that simpler pedals will work
well for some individuals and not so well for others.  The unsatisfied
users may speak negatively on the pedal since it didn't work for them, and
in the end this may scare out potential users/buyers.  On the other hand,
a pedal with dual-knob tone controls may appeal to more users thus
increasing the positive feedback.  Eventually a "well designed" three-knob
tonestack might be even better.  Of course there is a limit where too many
knobs/options might render the pedal hard to use/understand and you enter
into the diminishing returns territory.  Consider for instance the MZ-2
(metalzone) with four tone knobs (Bass, Treble, Mid, Mid Freq).  Very
versatile indeed, however I've heard reports from people telling it took
them a long time (several days) until they found "their tone".  As with
most things, there is no definitve answer.

This is just food for thought. Maybe OT and more related to pedal
design issues, however I felt like letting it out anyway.

[pott]

Well thanks a lot guys, though I don't get much of this   

My Guv'nor schems also show an effects loop for some reason :s I don't quite get it...


Wait...so stm, you believe that the most obvious mods I could do would be the clipping section and the opamp?

Thing is, the pedals sound VERY different. Well about as different as 2 Marshall emulations . The CB has a lot more harmonics and juice to it, just a way nicer sound to my ears. The Guv'nor is a real good pedal but much flatter.

[pott]

Ahh can't edit my post...

Anyway what I failed to mention. I don't want to simplify the Guvnor, I'll keep the tone stack in. I just prefer the overall character of the CB and the schematics looked similar enough to swap a bunch of things around (though I can't find an LF833 opamp anywhere). Gain is not really an issue as both pedals have enough for me. Just the overall sound/harmonics/character.

[slacker]

I still think the first mods to do before changing the opamp are to change R1 and C1 on the ggg guvnor schematic to 1k and 0.22uF and R6 and C8 to 1M and 100pf. Apart from the tonestacks these are the biggest differences between the 2 pedals. This gives the CB a lot more total gain but also changes the way the gain is distributed between the 2 opamp sections, this is likely to have an effect on the overall sound, even at lower gain settings.
For example with the guvnor on maximum gain the first stage has a gain of about 46 and the second stage has a gain of 68 making a total of just over 3000. If my maths is correct then if you set the CB up with the same overall gain then the first stage has a gain of about 82 and the second stage has a gain of about 35.
As you can see the first stage in the CB is supplying most of the gain where as in the guvnor most of the gain is in the second stage. This will change the sound of the distortion and also as the first stage boosts frequencies above 720Hz and these frequencies are boosted more in the CB it probably changes the charactor of the sound as well.

[powerplayj]

(though I can't find an LF833 opamp anywhere).

LM833

[stm]

My Guv'nor schems also show an effects loop for some reason :s I don't quite get it...

Wait...so stm, you believe that the most obvious mods I could do would be the clipping section and the opamp?

Thing is, the pedals sound VERY different. Well about as different as 2 Marshall emulations . The CB has a lot more harmonics and juice to it, just a way nicer sound to my ears. The Guv'nor is a real good pedal but much flatter.

The effects loop was included probably thinking you'd like to place an Equalizer or a Delay pedal just after the Guv'nor, so you can command both pedals just with the Guv'nor's footswitch.

From what I've seen and your description on the two pedal sounds, I'd suggest you apply the four component changes mentioned by slacker. Apart from increasing max gain 3x, this will raise the filter frequency in the second opamp from about 1 kHz to 1,5 kHz--a step towards more brightness.

For even more sparkle, you may try removing the 470pF cap to ground at the very end of the circuit (after the 22k resistor).  This will take out another hi-cut filter set roughly for 5 kHz, again adding some more brightness.

As for the LM833, it is said (on another thread) to sound better than TL072, however the change shouldn't be so extreme, so you may live without it. If you can get one, make sure to place a DIP8 socket to try out a TL072, NE5532, LM833, 4558, etc. to see what suits you best.

[pott]

Thanks A LOT guys! That makes my life a lot easier hehe...I'll try them this weekend I think. Too bad for the LM833 (I ALWAYS say LF for some reason :s) but I like the TL072 so eh...