SSS #002 REDRAW DRAFT

[ViperDoc]

I've been looking at the SSS#002 schematic, many thanks to whoever put that together. I put together a redraw in KiCAD to put everything on one page and, in the process, discovered some questions I have. To whoever is interested, please let me know if you see any errors in the drawing. I added some safety features I usually draw in like secondary fuses, a thermistor on the hot AC primary leg, deleted standby, bias test points, adjustable output impedance, etc.

1) The FET circuit combines the supply voltage and switched input on the jack switch, as well as no connection to the output. I'm sure my drawing needs some correction, but what is the best way to draw that in?

2) The SSS#002 schematic suggests a non-adjustable fixed bias with a 3k3 dropper off of one of the HT secondary legs, and one of the layouts involves such a source with an ODS style adjustable pot with the 22K tail/ 10K adjustable pot. How would you correctly design adjustable fixed bias for the SSS#002 amp? Would you not use the Fender Twin bias tap?

Thanks,

Brian

REDRAW:
NEW "V7" VERSION ADDED 01-24-2024-- NOVAL SOCKETS ALIGNED TO LAYOUT, MANNING SIM VOLTAGES ADDED

SSS #002 V7.1 LAYOUT ALIGNED.pdf

NEW "V6" VERSION ADDED 11-13-2023-- EDITED RCOLGAN BIAS. THANK YOU, MARTIN! I'LL GET IT EVENTUALLY!
NEW "V5" VERSION ADDED 11-12-2023-- "V-" SUPPLY CIRCUIT CORRECTED TO TOP OF SUPPLY CAP, NOT BIAS POT LEG
NEW "V4" VERSION ADDED 11-09-2023--Changes notated on schematic. MANNING FILTER & BIAS MODS ADDED.
NEW "V3" VERSION ADDED 11-06-2023--

ORIGINAL:

SSS_002_revision_7_174.pdf

[rccolgan]

this is beautiful!! Solid start! I scanned through it and it looks good! I'll have to check in more detail in a few days

[ViperDoc]

this is beautiful!! Solid start! I scanned through it and it looks good! I'll have to check in more detail in a few days

I appreciate your feedback, sir. It appears I've used your chassis face as a guide for my drawing. On that note, the dpdt switches in this SSS002 draft appear to reflect a reverse orientation, so I'm working on redrawing those switches for an UP FOR ROCK, UP FOR DEEP, and UP FOR REVERB orientation. The trouble is, it looks so much cleaner as is. I'll see if I can work it all out.

[erwin_ve]

When Ryan Colgan dive deep in the Sss002 and later build one there were several corrections made. The original Sss002 schematic is full of errors, pls take that in mind.
Schematic link below has most things right, although bias is different and reverb mixer, dry side cathode need a 5uF cap instead of a 1uF cap.
https://ampgarage.com/forum/download/file.php?id=64065
Also good to mention: the lnfb resistor going to the cathode of the 1st stage needs to be 100k instead of 1M,
this sets the balance between high and lows and give the amp its silky texture.

On your first question I can't help you.
Second question: the link I added has a bias option at the cathode tail. Also the voltage for the PI driver tube exceeds today's 12ax7 specs.
There is a design, by Martin Manning, with a bipolar supply taken from the 50/60v bias tap. You get around +170v and -170v at the driver tube. I made a pcb for it, it is tested but not a schematic and layout for that option yet.

Erwin

[ViperDoc]

When Ryan Colgan dive deep in the Sss002 and later build one there were several corrections made. The original Sss002 schematic is full of errors, pls take that in mind.
Schematic link below has most things right, although bias is different and reverb mixer, dry side cathode need a 5uF cap instead of a 1uF cap.
https://ampgarage.com/forum/download/file.php?id=64065
Also good to mention: the lnfb resistor going to the cathode of the 1st stage needs to be 100k instead of 1M,
this sets the balance between high and lows and give the amp its silky texture.

On your first question I can't help you.
Second question: the link I added has a bias option at the cathode tail. Also the voltage for the PI driver tube exceeds today's 12ax7 specs.
There is a design, by Martin Manning, with a bipolar supply taken from the 50/60v bias tap. You get around +170v and -170v at the driver tube. I made a pcb for it, it is tested but not a schematic and layout for that option yet.

Erwin

Thanks for that, Erwin! I notice on that new schematic:

1) R53 adds a 100K prior to the pre-filter coil inductor which changes the .01/.001 mix a bit.
2) R41 2K2 LNFB placed on the reverb driver secondary.
3) The rearranged bias has a direct bias voltage with no bias reservoir capacitor. Is this off the HT secondary?
4) The OCF tail becomes a tail with an added pot for bias adjustment.

Anything else?

Brian

[ViperDoc]

Here's an updated version with the above considered:

SEE FIRST POST ABOVE.

[pompeiisneaks]

Here's an updated version with the above considered:

SSS #002 V3 DRAFT.pdf

It is often good to either add new attachments to the first post OR delete the old and replace the new in the first post so later when people come back, they get the 'latest and greatest' instead of battling what you're mentioning, having a hard time finding the 'actual good one'

~Phil

[ViperDoc]

Here's an updated version with the above considered:

SSS #002 V3 DRAFT.pdf

It is often good to either add new attachments to the first post OR delete the old and replace the new in the first post so later when people come back, they get the 'latest and greatest' instead of battling what you're mentioning, having a hard time finding the 'actual good one'

~Phil

Thanks, Phil. I will do that. [Edit: Done.]

[didit]

Hello --

Overall reads clear and correct to my eyes. Caveat though, unlike Ryan & Erwin my knowledge of this design relies on some possibly practical reading here and no applied build experience. Have indefinite long-term plans to build something along these lines, so nevertheless quite interested in your work.

Adding to the thread as both encouragement and because a few nits surfaced in review you might want to correct. It's been more than a year since last had KiCAD running, and don't recall some details. There are spots where signal connections cross that have "no connection" marking and others where there are none. Would be cool to have the reverb links labelled meaningfully as you've nicely done elsewhere. Number 1/2/3 seems an unnecessary holdover from the original schematic. Consistency, hobgoblins etc, but still better to be tidy.

Encourage taking up Erwin's suggestion to pull in Martin's bipolar supply, at least as an option. Confident Erwin & Martin will help guide you if asked.

Closing question: do you now plan to get on to doing PCB layouts?

Best .. Ian

[ViperDoc]

Hello --

Overall reads clear and correct to my eyes. Caveat though, unlike Ryan & Erwin my knowledge of this design relies on some possibly practical reading here and no applied build experience. Have indefinite long-term plans to build something along these lines, so nevertheless quite interested in your work.

Adding to the thread as both encouragement and because a few nits surfaced in review you might want to correct. It's been more than a year since last had KiCAD running, and don't recall some details. There are spots where signal connections cross that have "no connection" marking and others where there are none. Would be cool to have the reverb links labelled meaningfully as you've nicely done elsewhere. Number 1/2/3 seems an unnecessary holdover from the original schematic. Consistency, hobgoblins etc, but still better to be tidy.

Encourage taking up Erwin's suggestion to pull in Martin's bipolar supply, at least as an option. Confident Erwin & Martin will help guide you if asked.

Closing question: do you now plan to get on to doing PCB layouts?

Best .. Ian

Thanks, Ian. All feedback is appreciated. I waffled on the NC symbols and ended up removing them, but clearly not all... Good call on a more homogenous connection nomenclature. Considered!

Who has the bipolar supply sketch for this amp? How does it change for the SSS style? I will search for it. I found Martin's filter mod and put that on an up-and-coming V4 version. [EDIT: FOUND IT. https://ampgarage.com/forum/viewtopic.php?t=29882. ]

[ViperDoc]

V4 version with Manning Filter & Bipolar Bias Mods added above.

[martin manning]

Nice work here! I have a schematic that I believe has all of the mods/corrections included. I'll compare and see if we agree. I also have a PCB design for the bipolar supply ready to go. It would be an easy conversion since the dimensions and mounting centers match the original rectifier/bias supply board.

[ViperDoc]

Hello --

Overall reads clear and correct to my eyes. Caveat though, unlike Ryan & Erwin my knowledge of this design relies on some possibly practical reading here and no applied build experience. Have indefinite long-term plans to build something along these lines, so nevertheless quite interested in your work.

Adding to the thread as both encouragement and because a few nits surfaced in review you might want to correct. It's been more than a year since last had KiCAD running, and don't recall some details. There are spots where signal connections cross that have "no connection" marking and others where there are none. Would be cool to have the reverb links labelled meaningfully as you've nicely done elsewhere. Number 1/2/3 seems an unnecessary holdover from the original schematic. Consistency, hobgoblins etc, but still better to be tidy.

Encourage taking up Erwin's suggestion to pull in Martin's bipolar supply, at least as an option. Confident Erwin & Martin will help guide you if asked.

Closing question: do you now plan to get on to doing PCB layouts?

Best .. Ian

Haha. Thanks. PCBs are above my pay grade, but it would fun to learn how to do them well. I will defer to the ranks.

[didit]

[...]
Closing question: do you now plan to get on to doing PCB layouts?

Best .. Ian

Haha. Thanks. PCBs are above my pay grade, but it would fun to learn how to do them well. I will defer to the ranks.

OK, fair enough. Asked for a few reasons. I did up board for the FET circuit and had to scratch together some necessary footprints that could be shared -- switchable FET boost. Might also readily share the full board, though it needs a last long-deferred up-rev before any escape into the wild. Also, would like to see readily available PCB options for each of cornerstone elements of various favourite amps. Hope to get back to design and build in 2024.

Best ..

[ViperDoc]

Well, this has definitely been a work in progress. V5 just posted. It corrects the negative bipolar bias supply source to the supply cap, not the leg of the bias pot. V4 took it from the bias pot leg, which is wrong. My bad.