Zener diode changes on a Ceriatone Chupacabra/Yeti?

[ledvedder]

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

Done! MPSA06s and 2N5400s ordered.

Now I just have to figure out the easiest way to test these without having to remove and replace them on the board over and over. Nik has explained it, but I'm still confused with his explanation.

"Say you want to experiment.

The easiest way is to hook it up.

Look at the current config - 1 side is grounded for the zeners on the board. Same with the MV, 1 lug is grounded.

The other side of the zeners, goes to the MV lug, thus they're actually across the MV pot.

So you can just wire from board - 0.22uf to the right leg of MV pot, zeners across to the ground lug of the MV pot

This is just to make it easy, without rewiring on the board, which can make it messy."

 

[rstites]

I don't know what the board looks like. Can you place sockets where the zeners go and then swap parts out for a bit to determine what you like? You can get sip sockets and snip off about amount you need.

EDIT: It'd be worth sockets for a couple of caps (as mentioned above) so you can swap those out to fine tune it for your needs. It's pretty easy to get the right amount of gain, then realize you have to fine tune the the lowpass and/or highpass filtering of the stage.

 

[ledvedder]

I tried MPSA06, 2N5400s, and 1N4733As. The first 2 were fairly similar but the 1N4733A was a lot of saturation and volume loss. I had to set the master volume on 5 with them to get the same volume I was getting on 2 with the transistors.

 

[scottosan]

I tried MPSA06, 2N5400s, and 1N4733As. The first 2 were fairly similar but the 1N4733A was a lot of saturation and volume loss. I had to set the master volume on 5 with them to get the same volume I was getting on 2 with the transistors.

Every one of those should have given you more saturation and and volume loss than the stock chupa configuration. how did you have them wired?

 

[ledvedder]

I tried MPSA06, 2N5400s, and 1N4733As. The first 2 were fairly similar but the 1N4733A was a lot of saturation and volume loss. I had to set the master volume on 5 with them to get the same volume I was getting on 2 with the transistors.

Every one of those should have given you more saturation and and volume loss than the stock chupa configuration. how did you have them wired?

They did, but the last one was too much. I alligator clipped them from the middle lug of the era switch to ground.

 

[scottosan]

what other values do you have?

 

[ledvedder]

what other values do you have?

I pretty sure the amp has 2x20v in 80s mode and 2x9v in 90s mode. The 1N4733A is 5v so 2x5v. Then, I just have 2xMPSA06 and 2x2N5400 transistors.

 

[ledvedder]

What tonal changes would I hear if using asymmetrical clipping (2 different zener voltages) as opposed to symmetrical (2 of the same zeners)?

What about LEDs? I've read some things about using them also?

 

[FourT6and2]

I hooked up my zener decade box to my stock Chupa and that really surprised me. I didn't think it would make a difference but there is an audible difference between the stock zeners and the ones I bought from Mouser even though two of them are the same voltage. Stock values are 20v on one side and 9.1v on the other. And whatever 20v zeners I bought sound night and day better than the stock ones. Same amount of gain, but it's almost like the type of clipping is different or something. It's more clear and more of a growl at the same time.

I think 1N4746 is a good value in this amp. And between the MPSA06 and 2N5401, I prefer the MPSA06, which is surprising since they are 4v and the 5401s are 5v. But the 5401s seem like they clip harder and are more compressed and grainy compared to the MPSA06, which have more growl and clip a tiny bit LESS. They add a tiny bit of vocal cocked wah effect. But maybe I swapped the two around by mistake. I will have to cut the heat shrink, doh!

Anyway, this amp absolutely spits fire now.

I grabbed a bunch of zener values from 24v down to 9.1v and then the two types of transistors (5v and 4v). 24v down to 16v all sound good. Just incrementally more clipping and compression. 12v, 9.1v, and the 5v transistors... I don't like them. The 4v transistors sound pretty cool for a super modern metal sound with a unique sort of vocal effect. But again, I need to double check what I actually used because I might have switched those around by accident.

If I had to pick two values, I'd go with 20v and 16v. 18v is a good middle ground too if you just wanted to build an amp with one option.

 

[SpiderWars]

Try connecting the pair of 2N5400s to the MPSA06s, it should sound similar (in terms of clipping/volume drop) to the 20v zeners. But it will sound a little different. It might not be aggressive enough for you but for a 'lower gain' option it's at least worth a try.

EDIT: I wonder if the difference in same value zeners could be heat applied during soldering? Nik's work has always generally looked pretty clean to me but yours is on another level. Could that explain it?

 

[psychodave]

I hooked up my zener decade box to my stock Chupa and that really surprised me. I didn't think it would make a difference but there is an audible difference between the stock zeners and the ones I bought from Mouser even though two of them are the same voltage. Stock values are 20v on one side and 9.1v on the other. And whatever 20v zeners I bought sound night and day better than the stock ones. Same amount of gain, but it's almost like the type of clipping is different or something. It's more clear and more of a growl at the same time.

I think 1N4746 is a good value in this amp. And between the MPSA06 and 2N5401, I prefer the MPSA06, which is surprising since they are 4v and the 5401s are 5v. But the 5401s seem like they clip harder and are more compressed and grainy compared to the MPSA06, which have more growl and clip a tiny bit LESS. They add a tiny bit of vocal cocked wah effect. But maybe I swapped the two around by mistake. I will have to cut the heat shrink, doh!

Anyway, this amp absolutely spits fire now.

I grabbed a bunch of zener values from 24v down to 9.1v and then the two types of transistors (5v and 4v). 24v down to 16v all sound good. Just incrementally more clipping and compression. 12v, 9.1v, and the 5v transistors... I don't like them. The 4v transistors sound pretty cool for a super modern metal sound with a unique sort of vocal effect. But again, I need to double check what I actually used because I might have switched those around by accident.

If I had to pick two values, I'd go with 20v and 16v. 18v is a good middle ground too if you just wanted to build an amp with one option.

If I understand it correctly, the first Cameron “Ocean” mod was just a regular Jose but with a specific zener (or transistor) brand? I believe they were gold pinned as well. The zeners has a different sound to them. I do know they can’t be found anymore, or at least Mark has never found them again.

I also know from experience glass and metal zeners sound different. It crazy all of the tonal differences out of these little parts.

 

[Bloodrock]

The best mod you can do to a ceriatone is to swap out the awful 56k slope resistor for a proper 33k to bring back the proper Marshall midrange grind.

 

[FourT6and2]

The best mod you can do to a ceriatone is to swap out the awful 56k slope resistor for a proper 33k to bring back the proper Marshall midrange grind.

I've never seen a 56K slope resistor in a Chupacabra or Yeti. If you have, it wasn't put there by Ceriatone. And 33K does sound good, but I prefer either 36K or 39K, depending on other things in the circuit like the treble cap and treble peaker.

Also Marshall used 56K in some amps.

 

[FourT6and2]

If I understand it correctly, the first Cameron “Ocean” mod was just a regular Jose but with a specific zener (or transistor) brand? I believe they were gold pinned as well. The zeners has a different sound to them. I do know they can’t be found anymore, or at least Mark has never found them again.

I also know from experience glass and metal zeners sound different. It crazy all of the tonal differences out of these little parts.

Well I'm surprised because the 20v and 9.1v zeners Ceriatone uses appear to be the same as the ones I got. They're glass. Same size. Probably a different brand. So who knows. I've not tried metal ones. The amount of clipping sounds the same, but there is a slightly different character. Hard to put my finger on it. I did orient them differently though. Ceriatone has the cathodes opposing. I wired them up facing each other. But that shouldn't make any difference.

How do glass vs metal vs plastic zeners compare in your experience?

Try connecting the pair of 2N5400s to the MPSA06s, it should sound similar (in terms of clipping/volume drop) to the 20v zeners. But it will sound a little different. It might not be aggressive enough for you but for a 'lower gain' option it's at least worth a try.

Like run them in series?

EDIT: I wonder if the difference in same value zeners could be heat applied during soldering? Nik's work has always generally looked pretty clean to me but yours is on another level. Could that explain it?

I doubt it. Maybe? Does heat from the iron permanently alter a component like a zener diode? Or is it heat while it's in a circuit? I know heat affects other components, but mostly only heat during operation. Like the value of a carbon comp resistor drifts as it heats up during operation. I do know the zeners I bought are all rated for 1.3 watts, but all the other ones available were rated lower. It didn't matter to me, that's just what I went with.

 

[SpiderWars]

Try connecting the pair of 2N5400s to the MPSA06s, it should sound similar (in terms of clipping/volume drop) to the 20v zeners. But it will sound a little different. It might not be aggressive enough for you but for a 'lower gain' option it's at least worth a try.

Like run them in series?

Yes. My King Kong had 2N5400s on the board for the higher gain clipping but the wires were connected underneath. I just disconnected the wire at the Era switch and inserted the MPSA06s there.

 

[scottosan]

Different diode types may clip differently. Although most silicon type of a similar spec should sound the same. Now, if you have a germanium vs silicon diode of similar forwarding voltage or zener coktage drop they will likely sound different. There is a tern called hard knee vs soft knee used to describe the effect on the waveform. https://www.diystompboxes.com/smfforum/ ... ic=74209.0

 

[FourT6and2]

Different diode types may clip differently. Although most silicon type of a similar spec should sound the same. Now, if you have a germanium vs silicon diode of similar forwarding voltage or zener coktage drop they will likely sound different. There is a tern called hard knee vs soft knee used to describe the effect on the waveform. https://www.diystompboxes.com/smfforum/ ... ic=74209.0

The ones I bought from Mouser are Vishay zeners. Glass package, 1.3W. No idea what is actually in my stock Chupa since it's an early production version and the component used there is about the size of a capacitor actually. I might have to break one open. Newer amps from them have zeners. They look the same as the ones I bought, but probably a different brand and different specs on the datasheet even though they're the same clamping voltage. So who knows. But yes... they do sound different. The Vishay 1.3W sound glorious! Really full and deep sound with a pleasant sort of clipping that gives the amp more balls. But I wonder how much of that is related to being mounted on a switch outside the amp?

I've been reading that glass zeners are photo-sensitive? Mine are outside the amp, with clear heat shrink, exposed to the light. I wonder if that has any real effect?

Switching back and forth between the stock 20v and the 20v on my switch, There is no volume drop. So the clamping amount is the same. But the character of the clipping is different for sure.

 

[FourT6and2]

Oh the wattage has to be part of it. The ones I got are 1.3W and the ones Ceriatone uses are physically smaller. About half the size. So probably 1/2W. So maybe it is a heat thing.

 

[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).

 

[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.