The SSS power amp.

[pinkphiloyd]

I'm using my phone to post this from the road so I want to be as brief as possible for now.

I built a JM sig. And I like it pretty well. It does what i expected. But I was looking at the schematic for SSS #0002 this morning. I'm intrigued by the cathode follower driving the power tubes. This is a brand new concept to me. So, basically, what the tweaker inside of me is wondering is, what differences would I notice if I added a tube to my JM sig, moved my bias supply from the bias tap of my PT to that of the HT, and, you know, basically swapped the whole power amp section to that of number 2? Thanks!

[mhartman]

Check out this thread/layout: https://tubeamparchive.com/viewtopic.ph ... highlight=

The preamp setup is very similar to the JM, but with filters. The PI and power section in the layout will show you how to convert your amp.

[pinkphiloyd]

I saw that when I was looking around, and took notice, believe me. I bookmarked the layout "just in case." I don't have any interest in going full SSS, filters and all, yet, but I'm really intrigued by the idea of adding the cathode follower to the JM. Mulling it over. Thanks!

[pinkphiloyd]

Man. After listening to every clip I could find of your SSS, I'm thinking a 50W version of this might be next for me. Are all of your clips in rock mode, or is the jazz setting featured anywhere?

[mhartman]

Thank you. The clips are all in Rock mode. I'm not a fan of the Dumble Jazz setting. Too dull for my tastes.

[pinkphiloyd]

Good to know. If I do this, I'll just go permanent rock mode.

Here's my next dumb question. Trying to decided if I'd do the FET or not. I've been looking at the actual #2 schematic, and, I feel like an idiot, but I don't get why part of the power supply is off in another little box labeled "FET." I have a fairly solid grasp on FETS. I understand the biasing, etc. I just don't get what's up with the power supply here. Where is this section actually originating?

And finally, my (hopefully last for awhile) idiotic question. Would I notice a big difference employing the built in FET rather than just using one of the many JFET or MOSFET booster pedals I've built in front of the normal input?

[mhartman]

The FET is basically a built-in pedal at the front of the amp. It is powered off of the same node as V1. No real connection to the power supply with the FET. I think the FET is OK, but I think I'll build a Katana-like circuit into the front end of my next one instead of the Dumble FET circuit. That being said, you can just go with pedals.

[pinkphiloyd]

That's what I figured I'll just run one the EP boosters or SHO's I built in front of it. Save some chassis real estate. Thanks!

[Duble]

If you plan on leaving the fet out, make sure to emulate its loading on the stages by putting a 150k Resistor to ground off the last node in your power supply.

The FET circuit has many short comings especially since it flips the phase on the input. It was no doubt a great idea and way ahead of its time way back when dumble first started making amps. It seems almost redundant now with all the stomp boxes available today, many that do a much better job at changing the input impedance and/or boosting the input without unwanted coloring. On the contrary, it does add a great crunchy artifact with the 70's voicing.

[amplifiednation]

I think the cathode follower adds a stiffer response and will give more of an SRV type tone than the blackface vibe you get from the JM. It's like a "clean lead" sort of thing, and more hi-fi.

[drrico]

The FET is basically a built-in pedal at the front of the amp. It is powered off of the same node as V1. No real connection to the power supply with the FET. I think the FET is OK, but I think I'll build a Katana-like circuit into the front end of my next one instead of the Dumble FET circuit. That being said, you can just go with pedals.

Hola Miguel, this is Rik. Have you checked out the Echoplex 2 circuit? I just ran a Chase Secret Pre into the SSS #005 I picked up from you and it is really cool. I could lend it to you if you want to check it with your builds...Chewier than the FET and can be dialed to vary the load. Quite cool with a Telecaster when looking for a 20,000 lb tweed sound.