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If I wanted to dip my toes into the Jose mod waters and lose all "all tube cred"...

Essentially we're talking about a couple zeners hung off a triode signal lead, after a coupling cap, sent to ground, right?

So at it's most simple (if I understand the schematics I'm looking at), taking the lead that feeds the tone stack and splitting it off with a switch, and adding 2 20v zeners to ground.

Does it change if that signal is coming off a plate instead of a cathode?

Have I lost any remaining respect?

What "Jose mod"??
Is this about the Paul Ruby buzz mod?

Talking about the Jose Arredondo Marshall clipping mods from the 80s. The Ceriatone Chupa has what I assume is a good example of it.

Ugh, I accidentally quoted myself again. see the post above

Using diodes inside tube amps for clipping is something that Marshall did during their lowest time, the infamous jCM900 era
those diodes destroy a tube amp's dynamic range and touch sensitivity, as well as changing its valve overdrive tone to a harsh chain-saw sound. I once helped talk a guy through how to remove the solid state c**p from his JCM900 and he loved how it opened up the dynamics of his amp, like a "real" Marshall and also made it louder.

Oh yeah, I had a JCM900 I'm the 90s and it was garbage. Traded it away within a couple months. But it seems like people are happy with the diode stuff Friedman has done and some others (heard good things about the Marshall Silver Jubilee), and I wanted to get a taste of it. Switchable of course. I'll prob hate it, but I want to experience that.

cstenger5 wrote: ↑

Mon 11/08/21 5:45 pm

Oh yeah, I had a JCM900 I'm the 90s and it was garbage. Traded it away within a couple months. But it seems like people are happy with the diode stuff Friedman has done and some others (heard good things about the Marshall Silver Jubilee), and I wanted to get a taste of it. Switchable of course. I'll prob hate it, but I want to experience that.

Put a emoji on the switch and you'll be golden.

Oh yeah? Well just for that I'm building a modeling amp.

Chris,

The Jose modded amps were 50 and 100 watters. While the power section will distort if pushed hard and loud enough, they got a lot of their characteristic sound with preamp distortion, and in some amps, either a pre-tone stack master or both a pre and post master, and added clipping diodes or transistors. They do add great distortion while cutting serious volume, so they can be great fun to play with. But, I would say that you are probably not going to get a Friedman sounding amp out of an 18W Lite engine. It's not going to happen. These amps are set up to distort the power section and that's that. Others have done 18W Plexis and other high gain variants with success, but if you are seriously trying to get all the modern flavors of ultra heavy distortion, just build a big amp with all the switches and mode changes and get it out of your system

Thanks for the thoughtful response! And you've hit the nail on the head... Getting it out of my system is precisely what it's about. A bunch of people did and dig this thing, so I feel the need to do it and then see what I think, knowing there's an 80% chance it's not for me. And the context part is really helpful. I'm not into higher watt amps, so that might just be what I need to know in order to just **** the door in the idea (until I get stuck on it again )

There's really no right answer. At the end of the day, amps are tools to a musician. If you need and dig that sound, you should have it as part of your tool kit. I think it's a worthy experiment to adapt a high gain front end to a 2 or 4xEL84 backend. I made a very high gain 4xEL84 amp a while back that was absolutely smashing. Just ferocious. But it was not close to the 18W on really any level. Totally different thing; different transformers, different power supply, four stage preamp, and very different voltages. It did sound quite monstrous though with a widebody and rear ported 1x12 with an EV.

this schematic shows them placed before the tonestack and feeding off the cathode,looks like you can bypass or switch between the type of zeners for different clipping,might be of use to you.

Germanium and zener diodes are fun. They can really pull down the output volume and give a satisfying, thumpy good grind at bedroom friendly volumes. You can use transistors as well.

You should give it a go. I've heard some great amps with zener clipping in the preamp still feeding into an overdriven power amp. It's not just for a clean output stage and I guarantee the big names who got Jose mods done back then didn't then wind back the master to ensure the EL34s weren't overdriving while getting those iconic tones live and in the studio.

Not sure I've seen anyone try it on the 18 Watt amp platform...... You might've actually come up with a suggestion that's new.

A couple of years ago, I built a 20 watt amp using the Chupacabra preamp. I liked it so much that I built a second one with 25 volts more in the B+. I like that one too. The one with the higher B+ is a little brighter sounding, but still a monster of an amp.

Mike

The Chupacabra is a great sounding design. I built a 100W version way back when. Very warm sounding amp and the distortion was smooth. The 430k boost stage made it a bit more complex (and distorted).

The power section in mine uses a 6.6K OT and is cathode biased. I can use 6L6, 5881, EL34 without a need to re-bias. I like the Tung-Sol 5881s the best. They seem to bring out the harmonics created by the the preamp.

As I mentioned earlier, I built two of these. One uses a 275-0-275 transformer and the other one uses a 300-0-300 transformer. Both are identical except for the Power Transformers. The one that uses the 300-0-300 transformer was a bit brighter than the lower voltage one. The lower voltage one sounds the best when cranked.

Mike

My lower voltage version of that amp has a plate voltage of 340 volts and was measured at 20 Watts into an 8 ohm load. I haven't measured power output of the other one, but it has a plate voltage around 360 volts. I am very pleased with both of them.