Zener diode changes on a Ceriatone Chupacabra/Yeti?

[paulyc]

This thread delivers. Thanks to all you amp nuts ! Great discussion.

 

[V2a]

Would something greater than 20v work? This way I'd have a mode with even less clipping than the 80s mode with the 20v zeners. That's what I'm looking for, to give an eve less gainy, more classic rock mode.

What you really want to do is add some resistance in series with the zener diodes. Kevin O'Connor calls this a 'compliance' resistor; what it does is round off the clipping so that it is not so harsh. More resistance = less harsh. Try 10k (which is what Dave Friedman uses in his SAT switch).

I believe the Ceriatone Jose variants already have a 10k and .22uF cap in series before the clipping diodes.

That's a different 10k resistor. The compliance resistor is in the path to ground.

 

[technomancer]

Would something greater than 20v work? This way I'd have a mode with even less clipping than the 80s mode with the 20v zeners. That's what I'm looking for, to give an eve less gainy, more classic rock mode.

What you really want to do is add some resistance in series with the zener diodes. Kevin O'Connor calls this a 'compliance' resistor; what it does is round off the clipping so that it is not so harsh. More resistance = less harsh. Try 10k (which is what Dave Friedman uses in his SAT switch).

I believe the Ceriatone Jose variants already have a 10k and .22uF cap in series before the clipping diodes.

That's a different 10k resistor. The compliance resistor is in the path to ground.

From what I understand the Friedman sat is 10k -> 100nF -> mpsa06 pair with a 1M in parallel of the transistors to ground. Are you talking about the parallel 1M to ground?

 

[SpiderWars]

The 1M parallel resistor 'simulates' the normal Jose 1M Master volume. That resistor has to be there. The 10k series resistor and 100nF cap is similar (but not the same as) to the typical Jose setup. The Friedman 10K and 100nF 'branch off' the signal path to ground. The Jose has the 10K/.22uF (or whatever value) all in series with signal path. psychodave has commented how he doesn't like the Friedman method. I don't have side-by-side experience so I can't speak to that but I trust Dave's ears (psychoDave that is). My Jose is kind of Friedman-ish EXCEPT for that, my diodes/MV are like the old Jose method. And I used a .33uF cap instead of .1uF as well but I didn't experiment with that. I just didn't want to lose any fullness.

EDIT: the Friedman way is MUCH easier to implement to an existing amp that was not Jose-ified but for a new build it's not a big deal. I found that if I moved the treble cap to the pots (point-to-point) it freed up some turrets so the Jose method wasn't that hard to implement.

 

[technomancer]

The 1M parallel resistor 'simulates' the normal Jose 1M Master volume. That resistor has to be there. The 10k series resistor and 100nF cap is similar (but not the same as) to the typical Jose setup. The Friedman 10K and 100nF 'branch off' the signal path to ground. The Jose has the 10K/.22uF (or whatever value) all in series with signal path. psychodave has commented how he doesn't like the Friedman method. I don't have side-by-side experience so I can't speak to that but I trust Dave's ears (psychoDave that is). My Jose is kind of Friedman-ish EXCEPT for that, my diodes/MV are like the old Jose method. And I used a .33uF cap instead of .1uF as well but I didn't experiment with that. I just didn't want to lose any fullness.

EDIT: the Friedman way is MUCH easier to implement to an existing amp that was not Jose-ified but for a new build it's not a big deal. I found that if I moved the treble cap to the pots (point-to-point) it freed up some turrets so the Jose method wasn't that hard to implement.

I always figured that was why the 1M was there... but was just trying to figure out what 10k V2a was talking about.

 

[SpiderWars]

TBH, I assumed V2a was talking about an additional 10k resistor but his Friedman comment threw me. I have seen at least one variation that has a pot in series with the diodes so that you can sort of 'attenuate' the signal the diodes see and soften the clip but I'll let V2a clarify.

 

[V2a]

The 1M parallel resistor 'simulates' the normal Jose 1M Master volume. That resistor has to be there. The 10k series resistor and 100nF cap is similar (but not the same as) to the typical Jose setup. The Friedman 10K and 100nF 'branch off' the signal path to ground. The Jose has the 10K/.22uF (or whatever value) all in series with signal path. psychodave has commented how he doesn't like the Friedman method. I don't have side-by-side experience so I can't speak to that but I trust Dave's ears (psychoDave that is). My Jose is kind of Friedman-ish EXCEPT for that, my diodes/MV are like the old Jose method. And I used a .33uF cap instead of .1uF as well but I didn't experiment with that. I just didn't want to lose any fullness.

EDIT: the Friedman way is MUCH easier to implement to an existing amp that was not Jose-ified but for a new build it's not a big deal. I found that if I moved the treble cap to the pots (point-to-point) it freed up some turrets so the Jose method wasn't that hard to implement.

I always figured that was why the 1M was there... but was just trying to figure out what 10k V2a was talking about.

Well, the 1M does not have to be there, but it does affect things a bit.

The 10k is the same one that is in the Friedman SAT switch. Without that compliance resistor, you have a hard-clipped signal. The compliance resistor softens the effect of the zeners (or transistors, LEDs, etc) and rounds the clipped signal. You can go quite a bit higher than 10k for a more tube-like distortion.

The resistor (usually 10k) that is between the cathode of the cathode follower and the tone stack acts to isolate the clipper from the cathode; this helps in some circumstances but is often not needed.

TBH, I assumed V2a was talking about an additional 10k resistor but his Friedman comment threw me. I have seen at least one variation that has a pot in series with the diodes so that you can sort of 'attenuate' the signal the diodes see and soften the clip but I'll let V2a clarify.

Yes the pot in series with the diode is wired as a variable (compliance) resistor.

BTW - ALL of this is covered in detail in Kevin O'Connor's first TUT book (TUT = 'the ultimate tone').

 

[SpiderWars]

Interesting, I always thought (and read) that the resistor in parallel with the clippers had to be there.

 

[FourT6and2]

Yeah, typical Jose-ified mods have the 10K resistor and a 0.22uF - 0.68uF cap (to block DC) in series with the MV. Whatever V2a is talking about is a resistor in series with the diodes to ground. I've not tried that. I don't particularly like how Friedman amps sound. They have a somewhat round attack and are not aggressive enough for me.

 

[scottosan]

The 1M parallel resistor 'simulates' the normal Jose 1M Master volume. That resistor has to be there. The 10k series resistor and 100nF cap is similar (but not the same as) to the typical Jose setup. The Friedman 10K and 100nF 'branch off' the signal path to ground. The Jose has the 10K/.22uF (or whatever value) all in series with signal path. psychodave has commented how he doesn't like the Friedman method. I don't have side-by-side experience so I can't speak to that but I trust Dave's ears (psychoDave that is). My Jose is kind of Friedman-ish EXCEPT for that, my diodes/MV are like the old Jose method. And I used a .33uF cap instead of .1uF as well but I didn't experiment with that. I just didn't want to lose any fullness.

EDIT: the Friedman way is MUCH easier to implement to an existing amp that was not Jose-ified but for a new build it's not a big deal. I found that if I moved the treble cap to the pots (point-to-point) it freed up some turrets so the Jose method wasn't that hard to implement.

I always figured that was why the 1M was there... but was just trying to figure out what 10k V2a was talking about.

Well, the 1M does not have to be there, but it does affect things a bit.

The 10k is the same one that is in the Friedman SAT switch. Without that compliance resistor, you have a hard-clipped signal. The compliance resistor softens the effect of the zeners (or transistors, LEDs, etc) and rounds the clipped signal. You can go quite a bit higher than 10k for a more tube-like distortion.

The resistor (usually 10k) that is between the cathode of the cathode follower and the tone stack acts to isolate the clipper from the cathode; this helps in some circumstances but is often not needed.

TBH, I assumed V2a was talking about an additional 10k resistor but his Friedman comment threw me. I have seen at least one variation that has a pot in series with the diodes so that you can sort of 'attenuate' the signal the diodes see and soften the clip but I'll let V2a clarify.

Yes the pot in series with the diode is wired as a variable (compliance) resistor.

BTW - ALL of this is covered in detail in Kevin O'Connor's first TUT book (TUT = 'the ultimate tone').

the master volume placement on the Jose is not the same as the Friedman. The 1M pot is in parallel with the diodes unlike Dave's. Dave's stock diode replacement is too dark in the stock BE arangemnt in my opinion and needs to be compensated on the NFB circuit to keep it from getting buried in a live situation

 

[paulyc]

If you think about all the hoopla about Fuzz Face circuits and clones (and Klons and Klones as well), an AWFUL lot of attention is paid to NOS transistors being used for the clipping, so it stands to reason that using various kinds of diodes, transistors, LEDs etc would produce different results...

 

[FourT6and2]

Grab some 2N5400s while you are at it. I prefer these over the MPSA06 although they are very close. On these you’d wire them the exact opposite as the MPSA06, snip leg 3 as well

Just saw this post. Scott, what do you mean you gotta hook them up the opposite as MPSA06? I have both my 2N5401 and MPSA06 wired the exact same way. Pin 3 cut. Pin 1 hooked together. Pin 2 is the in/out from pot to ground. I get that it's PNP vs NPN. But... it's just like a zener, no? You can run zeners anode to anode or cathode to cathode. Doesn't make a difference either way. Same thing with transistors being run as zeners.

 

[scottosan]

Grab some 2N5400s while you are at it. I prefer these over the MPSA06 although they are very close. On these you’d wire them the exact opposite as the MPSA06, snip leg 3 as well

Just saw this post. Scott, what do you mean you gotta hook them up the opposite as MPSA06? I have both my 2N5401 and MPSA06 wired the exact same way. Pin 3 cut. Pin 1 hooked together. Pin 2 is the in/out from pot to ground. I get that it's PNP vs NPN. But... it's just like a zener, no? You can run zeners anode to anode or cathode to cathode. Doesn't make a difference either way. Same thing with transistors being run as zeners.

Correct. Old Post. Only relevant if doing mixing of diodes

 

[paulyc]

He did it on lots of amps. It’s really a great idea. I wish my CCV had dual rotary clipping switches on both the lead and solo masters. You could do tons of tone shaping.

Dave, where would you mount the rotary switches if you were going to do it ? Could they be put on the back ?

 

[geezberry]

Grab some 2N5400s while you are at it. I prefer these over the MPSA06 although they are very close. On these you’d wire them the exact opposite as the MPSA06, snip leg 3 as well

opposite how?

 

[SpiderWars]

opposite how?

He later mentioned that it doesn't matter. With the transistors you are connecting the base and emitter and snipping the collector. Just as with the zeners, you just connect them facing in opposite directions. So base to base or emitter to emitter, doesn't matter. If you connect them base to emitter then you just doubled the clipping threshold for ONE direction.

And imo if you are going to try them, try it like I mentioned years ago in this thread I think. Use 4 of them and connect pairs of them base to emitter. Then use those pairs like you would any zeners, i.e. connected facing opposite directions.