SSS 01 Layout

[martin manning]

Thinking about this a bit more the neon bulb can go from out 1 to ground, or from out 1 to out 2 (post above edited... again).

I don't have any way to simulate a neon bulb, but using an 82V Zener the difference is that using out1 to ground produces current flow in a square pulse with approximately equal on-off time, and out 1 to out 2 has a triangular pulse with a lot of off time. Assuming the typical (Fender) arrangement where the LDR shunts signal to ground, the guitar sound would be modulated inversely since the LDR's resistance drops when the neon bulb is on. No doubt this circuit will have to be tested with the actual opto isolator to see which way sounds better.

The photo of the board shows three turrets near the oscillator, each with what looks like a shielded wire, plus the wires to the opto isolator. I have no idea what's going on there other than there must be leads for the pots and kill switch, and perhaps the oscillator signal is being used in some other way, like bias modulation somewhere, which could be selectable via a switch.

[Aaron]

Have nearly finished the tremolo.

Great work Martin, the layout fits with the schem that you posted. Although I did change C5, R8 and R9. You're schem was slightly different to the Magnatone. Will this effect the trem circuit or part of the circuit cause other bits were removed.
Also, I just don't know where/how you meant to hook up the opto-roach.

I was looking at schems of some other Magnatone amps, do you think the tremolo switch on the MP-1 might be similar to the switch used here?

Max Posted: Fri Aug 24, 2012 8:15 am Post subject:

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vibratoking wrote:
Personally, I am not interested in taking on a full, historically correct documentation task

I fully understand your personal point of view. Perhaps I just didn't make my intention clear enough:

If what in the end will be posted in the files section will be something else than what most here will think to be a 100% correct schematic and layout of SSS #001, I would propose not to name it "SSS #001". That's what I proposed. Not more - not less.

And I am fully aware, that Dumble schematics are floating around the net that AFAIK aren't correct, just because even very experienced techs are humans and we humans make faults. And by copy and paste these faults sometimes spread like the flu.

The layout is still based on 001 though. I see your point on not calling SSS 001 because some values and bits and pieces are guess work. But, it's a start and hopefully someone who has had access to SSS 001 will one day drop a visit in to the forum and blow our socks off with a verified schem

When everybody is in agreement with the values, I'll draw this up again. This was my first attempt using visio and now that I've started another layout I know this one can be a bit better.

Thanks,
Aaron

EDIT: revised layout posted further

[Colossal]

Great job Aaron!

[M Fowler]

Aaron fantastic work. I've been using Visio for 2 years and can't even come close to your work.

Mark

[wicker]

Just a quick hint for guys that would like to try amp with cathode driven power tubes - you can achieve the same result by implementing transistors based driver (like IRF830) - since the cathode/source/emmiter follower do not provide voltage amplification, the is no difference in sound (it was prooved, you can google it), it's cheaper than extra tube, some may try it.

[martin manning]

Aaron, I'm suggesting that the SSS circuit is an adaptation of the Magnatone LFO, and that the schematic I posted is what is in the SSS photo. The values of the resistors match the ones in the original, and you can see where they could match the SSS photo depending on red/orange and orange/brown color fidelity. The 0.047 and 0.068 caps may both be 0.047 or 0.068; it will work either way.

The neon bulb in the opto isolator could be connected in one of two ways as shown below, with different pulse shapes resulting. So, it's connected to the triode with the two 47k load resistors, either from pin 1 to pin 3, or from pin 3 to ground. I didn't look too closely... you may be able to tell from the picture.

To turn off the effect you just ground the LFO signal at the point I labeled Ft Sw. The oscillator runs all the time, so no delayed start for this one.

Also, I believe there is a solder point on the board for pin 7 of that tube.

[grtamp]

Hi , what type of reverb tank for this circuit.

Impressive work Aaron!!

[Max]

what type of reverb tank for this circuit.

AFAIK Alexander Dumble usually used a long Accutronics tank with 4 springs (2x2) for 100W SSS amps. But I know at least one (other) Dumble amp with reverb with an Accutronics tank with six springs (3x2). I would recommend to try both versions and use the one that is in best accord with personal taste.

For connecting tank and amp AFAIK Alexander Dumble usually used the same kind of coax cable as in the amp. According to the picture of SSS #001 it has originally been built using Columbia Flexfoam 1389. The technical specs of the Columbia Flexfoam 1389 coax cable you’ll find here: https://tubeamparchive.com/download/file.php?id=14336

Cheers,

Max

[vibratoking]

EDIT - moved to current end of thread

[martin manning]

Aaron points out that I changed the Magnatone schematic slightly with respect to the grid-cathode circuit of the driver. It doesn't make much difference, but here's a correction, back to the original. Vibrato, I would describe the effect on sound with the neon across out 1 and out 2 as "more off than on," about 40% on, and the neon from out 1 to ground as "more on than off," about 80% on. They are both pretty square pulse shapes, but I suspect the LDR will round off the corners a bit.

The previous circuit I posted has "on" times of about 50% and 70%, depending on the out1-out 2 connections. All of this is using an 82V Zener to simulate the neon bulb. I don't know which would sound better, but you can bet HAD played around with this until he found something he liked ;^)

[martin manning]

An AB763 trem circuit (which has the opto isolator driven off the plate of the driver stage), has an "on" time of 80%, again using a Zener to simulate the neon bulb. Based on that I guess we could say that the later circuit (posted just above), with the opto isolator connected from out 1 to ground (option 2) should be used as the baseline for now.

The trace of current through the Zener in the proposed SSS circuit is shown below. The sound is on (crests) when the neon is off (zero current). The AB763 circuit produces a waveform very similar to this.

[vibratoking]

Thank you Martin.

Attached is the latest version of the schematic. It is still not complete! There are still quite a few open issues. The upper right corner contains notes about the circuit and issues in the layout or between the layout and the schematic.

Please feel free to review and provide feedback.

Updated: 8/28/2012.
- added note about power supply issue in layout
- changed input to grid of V4A in tremolo
- added text regarding location of opto-isolator
- added mid accent label and cap value for #002

[vibratoking]

I found this picture on Livesey's of what I think we are calling SSS #001, but it is labeled SSS-100?

[Aaron]

Hi Vibra,

That's the amp. SSS-100 means Steel String Singer 100 watts.
The 001 is serial number 1.

Thanks,
Aaron

[Aaron]

Here is an updated layout based on SSS 001. (Finally)

I'm still a bit unsure on the red switch wiring for the tremolo, but would probably go the standard grounding for switching.

The power supply is based on SSS 002 and some values of the components taked from SSS 002 as well. But the layout should get you there.

Thanks,
Aaron

EDIT:- revised layout posted further