SSS 01 Layout

[Bombacaototal]

@mfowler thanks for sharing. I was referring to the green and blues one posted by aaron

I was also curious to hear this amp in action

[M Fowler]

https://tubeamparchive.com/download/fil ... &mode=view

This one?

[Bombacaototal]

https://tubeamparchive.com/download/fil ... &mode=view

This one?

Thanks a lot although I think the resolution is the same as the one posted previously on this thread

[M Fowler]

The resolution is very good on that one for me.

[Bombacaototal]

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, I am having a go at this tremolo circuit.

As far as the roach we can clearly see the Neon side connecting to the 47K plate and PIN 1 via the yellow wire. I think this busts the option 2 for the roach. There seems to be another side of the toggle switch between the two (the roach and the 47K plate/PIN 1)? Any idea of the purpose of this? It is not very clear that the other wire of the Neon side is connecting to PIN3/47K ground. But I will attempt like this.

On the LDR side there is a clear black wire going to ground at the 1K resistor. I think the grey wire on the LDR side is the signal from the Master (as per attachment). I just don't understand the second grey wire from the toggle going to the ground at the 100K (also attached).

[martin manning]

As far as the roach we can clearly see the Neon side connecting to the 47K plate and PIN 1 via the yellow wire. I think this busts the option 2 for the roach. There seems to be another side of the toggle switch between the two (the roach and the 47K plate/PIN 1)? Any idea of the purpose of this? It is not very clear that the other wire of the Neon side is connecting to PIN3/47K ground. But I will attempt like this.

I like option 2 (neon connected from plate to cathode), because I believe the intensity function will work better.

I would make some changes to the circuit, though:
- Increase the speed pot to 1M RA
- Get rid of the grid leak bias on the LFO; use a 1M grid leak, and a Red LED from the cathode to ground.
- Add a tail resistor to the intensity pot, say 220k, (but adjust to get the minimum intensity where you want it).
- In the photos it seems that HAD kept the two 4n7 to ground in the Maggie trem (either side of the 330k closest to the driver tube grid)... couldn't hurt.

On the LDR side there is a clear black wire going to ground at the 1K resistor. I think the grey wire on the LDR side is the signal from the Master (as per attachment). I just don't understand the second grey wire from the toggle going to the ground at the 100K (also attached).

Perhaps the toggle lifts the LDR from the circuit?

[Bombacaototal]

Thank you very much for the suggestions Martin. I really want to make this circuit work and be usable and therefore will surely experiment with your ideas.

I have everything wired up as per original and just missing the roach, which I ordered from 2 different places before Christmas but still haven’t arrived due to the holidays season.

As far as the 4n7 do you think there is one between the two 330k resistors as per original Magnatone? I cannot seem to trace it via the gut shot.

Voltages at 47k and 270k is just shy of 200V. My 6L6 plates are 456v. I think the magnatone runs at 320v?

Also I have a 12DW7 for the trem

[Bombacaototal]

As far as the roach we can clearly see the Neon side connecting to the 47K plate and PIN 1 via the yellow wire. I think this busts the option 2 for the roach. There seems to be another side of the toggle switch between the two (the roach and the 47K plate/PIN 1)? Any idea of the purpose of this? It is not very clear that the other wire of the Neon side is connecting to PIN3/47K ground. But I will attempt like this.

I like option 2 (neon connected from plate to cathode), because I believe the intensity function will work better.

I would make some changes to the circuit, though:
- Increase the speed pot to 1M RA
- Get rid of the grid leak bias on the LFO; use a 1M grid leak, and a Red LED from the cathode to ground.
- Add a tail resistor to the intensity pot, say 220k, (but adjust to get the minimum intensity where you want it).
- In the photos it seems that HAD kept the two 4n7 to ground in the Maggie trem (either side of the 330k closest to the driver tube grid)... couldn't hurt.

On the LDR side there is a clear black wire going to ground at the 1K resistor. I think the grey wire on the LDR side is the signal from the Master (as per attachment). I just don't understand the second grey wire from the toggle going to the ground at the 100K (also attached).

Perhaps the toggle lifts the LDR from the circuit?

Hi Martin, I just put together a quick schematic of the original and your mod suggestions. Would you please double check if I got them right?

There was another mod you mentioned earlier on the thread about having the 1M on the driver tube between the 8.2M and .047uF instead of where it is. I haven't added this to the mod schematic.

On the 4n7, if there is one on PIN2 and another between the 330K x 2 we are missing the .068uF capacitor on the PIN6...

[martin manning]

The oscillator mods are correct as I described. The LED will bias it with full gain potential at low frequencies, and give a visual indication that it is working.

On the driver stage, the two 47n to ground make low pass filters with the 330k's. The driver tube is grid leak biased with a 1M, so you could add a cathode bias resistor there.

Placing the neon across the plate and cathode exposes it to high voltage when the tube cuts off, so if you put it there, I suggest protecting it with a current limiting resistor, 47k-100k. Also, that configuration will leave the neon on when the foot switch grounds out the signal, which might explain the additional wiring in the photos. I think you will want to disconnect the neon when the LFO signal is grounded out if you do it that way. Running the neon from the cathode, or Fender-style in the anode circuit, avoids that issue. Running from the cathode, I would add a current limiting resistor.

I think there was a lot of experimentation going on in that trem circuit based on the condition of the board, and we don't have a clear picture of the circuit HAD settled on. You are in for some trial and error here.

[Bombacaototal]

The oscillator mods are correct as I described. The LED will bias it with full gain potential at low frequencies, and give a visual indication that it is working.

On the driver stage, the two 47n to ground make low pass filters with the 330k's. The driver tube is grid leak biased with a 1M, so you could add a cathode bias resistor there.

Placing the neon across the plate and cathode exposes it to high voltage when the tube cuts off, so if you put it there, I suggest protecting it with a current limiting resistor, 47k-100k. Also, that configuration will leave the neon on when the foot switch grounds out the signal, which might explain the additional wiring in the photos. I think you will want to disconnect the neon when the LFO signal is grounded out if you do it that way. Running the neon from the cathode, or Fender-style in the anode circuit, avoids that issue. Running from the cathode, I would add a current limiting resistor.

I think there was a lot of experimentation going on in that trem circuit based on the condition of the board, and we don't have a clear picture of the circuit HAD settled on. You are in for some trial and error here.

Thanks Martin, I am always up for some experimentation, hard work but fun...

As far as the two 4n7 to ground you think I should add them back (as per schematic below)?

As far as the roach, do you think the Fender approach will work? I did a mock up of doing it Fender style..I think the roach is where the challenge lies..

If not, and if sticking to the option 2 (neon connected from plate to cathode), besides adding the current limiter (also attached) I will have to figure out how to disconnect this without a relay...

I am also thinking of adding a manual switch between the LDR and the Master to get the trem completely out of the circuit of the amp..

[Bombacaototal]

Martin, the roach arrived and so the experiments started..

I am using the circuit as per original trace (ie 3.3M on the oscillator tube and without the two 4n7). I have connected the roach from plate to cathode. I can hear a ticking on the background which responds to the speed pot and to the intensity (after 12 o’clock). There is no effect on the actual guitar sound. I am running 200V on the plates. Tried 290v and 180v and also nothing

I will experiment more and report back

EDIT 1: running the roach form the cathode has absolutely no effect

EDIT 2: fender style has no effect, will try increasing the voltage. Tried from screens (450v) nothing, 280v (nothing), 180v (nothing)

[martin manning]

I would try it like this. Around 350V seems like a good place to be for the supply voltage. After some playing around, I think running it from the cathode is the best option.

Ticking says the oscillator is running. If you use an LED to bias, it should be flashing.

By current limiter I mean a resistor in series with the neon. Notice in the Fender setup the current through the neon is limited by the tube and its (100k) plate resistor.

[Bombacaototal]

Thanks for the further suggestions Martin. I could only get voltages at 400+ and between 300 and 180 with the dropping resistors in hand and the anodes I had without much chaos.

I am pretty sure the oscillator was running due to the ticking but unfortunately I did not try the led.

I did not get any joy with my attempts and the fact that Dumble gave up on a Footswitch and added that complicated 8 lug toggle, and also the possibility that I would have to disconnect the roach and lack of much further details about the original put me off in going much deeper into this circuit.

I reversed back to the tremolo of the Borderline Special (5+ hours of work), which is what my amp was originally designed for, and although it has problems of its own I have been studying this trem and have spent a few months with it already, and I can hear a tremolo there although with a bad ticking which is most likely due to a ground loop. I will do another post on this to see if I can fix the issues I have encountered.

[sluckey]

This may be of some interest to you...

http://sluckeyamps.com/trem/trem.htm

[rootz]

I would try it like this. Around 350V seems like a good place to be for the supply voltage. After some playing around, I think running it from the cathode is the best option.

Ticking says the oscillator is running. If you use an LED to bias, it should be flashing.

By current limiter I mean a resistor in series with the neon. Notice in the Fender setup the current through the neon is limited by the tube and its (100k) plate resistor.

Little side note. 12ax7 and au7 in one envelope is the 12DW7, not the 12BH7. The latter is a close cousin of the ECC99.