My take on Eric Johnson's Steel String Singer #005

[beasleybodyshop]

UPDATE:

I have attached my final schematic with annotations and voltages/part numbers at the bottom of this post. Happy building!

PS: I used a 100W Marshall Output Transformer

Hello everyone! I hope you all have been doing well in this trying time. I have had the good fortune to spend quite a bit of time with a few SSS#005 "clones" as of late, as I have had the good fortune of making acquaintance with a friend who is obsessed with all things Eric Johnson and has several SSS#005 type amps from several of the well known builders. So I thought I would share an interpretation on this amp. I have drawn a layout and schematic of what I have observed, but in the spirit of not cloning anything "to the letter" or to offend sensibilities I won't be offering "carbon copy" information so here goes:

Based on what I can observe, the SSS #005 clones out there share this common refrain: Skyliner EQ, Post PI driver tube, and unusually high negative feedback resistor. Also omits a choke in lieu of a large wirewound resistor. Circuit also seems to use a standard Fender reverb circuit with added Send (Dwell) and Return (level) controls. 12AT7 driver stage uses LNFB like in several Dumble designs.

In my interpretation of this circuit I have made some changes. Ive added Martin Manning's improved step filter design as well as his bipolar Cathode Follower driver power supply circuit that utilizes the 60vAC bias winding tap on a Fender style Power Transformer. Handful of tweaks here and there as well. For the FET stage, I'll be using a PCB for a Echoplex EP3 FET preamp. Running a quad of 6CA7s with a Fender Twin style power transformer for this interpretation.

Schematic and layout are not tested, however I have audited them both several time and can say with likely 90% accuracy that it will work as built, but Caveat Emptor applies. If anyone sees any glaring errors please share

Demo of this build is HERE:

https://www.youtube.com/watch?v=qchuuosfnVM

NOTE: THESE HAVE BEEN UPDATED

SSS#5 layout.pdf

SSS5 modded with loop V2 FINAL 10.3.23.pdf

[dorrisant]

Nice work... it figure that you'd gravitate toward an EP booster, right? I'll definitely look for errors later.
(Pulls up a chair)

Did you use Visio on the layout? If so, can you post the original?

[norburybrook]

Oh dear......

I thought I'd kicked this building lark.....


Is it different enough from a JM wonderland to warrant building?

I suppose I could mod my JM into this and find out



M

[Roe]

my main worry is the mixing of the dry and wet/reverb signals. Pics somehow suggest that the dry signal is sent to the reverb return pot. Both the wet and dry signal are sent to the input of the pot apparently.

[beasleybodyshop]

Yes the wet and dry signals are mixed in an unusual way. I did confirm this in more than one amp so people are either cloning the same mistake or it works haha!

The larger amount of NFB makes me think the amp would have more chime and grit when turned up. Playing through the 3 amps I spent time with confirms this - but still capable of great clean tones. I'll avoid silly terms for tone descriptions but they all sounded fantastic.

[beasleybodyshop]

I think the wet/dry is wired in a strange way as to keep the input impedance of the mixter stage from being loaded down by the reverb return.

[beasleybodyshop]

Nice work... it figure that you'd gravitate toward an EP booster, right? I'll definitely look for errors later.
(Pulls up a chair)

Did you use Visio on the layout? If so, can you post the original?

I used Inkscape. I exported as a PDF to scale so it's kinda large. I could try resending them as PNGs inline or something.

[mojotom]

Thanks a lot for that !!

I was rebuilding a Wonderland and tried today a Skyline mod on it, keeping the same bass pot and tail and quite like it.

Do you have the values of the dropping resistors for the power supply ?
That’s a very important parameter.

[Roe]

the pic suggests that both the wet and dry signal go to the input of the reverb return pot. this can't be the whole truth, unless the dry signal dissappears when you turn down the reverb pot

[beasleybodyshop]

the pic suggests that both the wet and dry signal go to the input of the reverb return pot. this can't be the whole truth, unless the dry signal dissappears when you turn down the reverb pot

Look here. Dry signal connects to top of Return pot. Wiper is attached to the reverb circuit. It is indeed a little odd but i did confirm this.

Annotation 2020-04-02 133414.png

[beasleybodyshop]

Roe, what you are seeing is the output of the filter circuit connecting to the top of the Return pot. Then a second shielded wire is going from that point to the grid input of the mixer stage. Not both wet and dry going to the top of the pot. the WET is connected to the wiper of the Return.

[Roe]

Roe, what you are seeing is the output of the filter circuit connecting to the top of the Return pot. Then a second shielded wire is going from that point to the grid input of the mixer stage. Not both wet and dry going to the top of the pot. the WET is connected to the wiper of the Return.

Sorry but I still see three shielded cables on the pic, two of which connect to the top of the pot and a third which connects to the wiper (in addition to a ground on the bottom of the pot).

The layout, by contrast, only got two cables (in addition to ground).

another pic:

My hypothesis is as follows:
Top of pot- one cable connects to the (high) filter, another to the grid of the mixer stage (V4a=
Viper- wet signal from reverb recovery stage
bottom - ground

[beasleybodyshop]

Yes - the two connections to the top of the Reverb pot are as follows:

1 - output connection from filter circuit
2 - goes from top of reverb Return pot to grid input of next stage

They are using the top of the Return pot as a daisy chain point to go to the grid input of the next stage.

[Roe]

Yes - the two connections to the top of the Reverb pot are as follows:

1 - output connection from filter circuit
2 - goes from top of reverb Return pot to grid input of next stage

They are using the top of the Return pot as a daisy chain point to go to the grid input of the next stage.

great, thanks for the confirmation!

[dorrisant]

I used Inkscape. I exported as a PDF to scale so it's kinda large. I could try resending them as PNGs inline or something.

No worries... I was just looking to manipulate the original drawing to generate other drawings with differences. If you don't mind, please post the Inkscape file. That will work just as well. Very nice looking layout!