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

[captaincoconut]

So I just take the voltage I get from the preamp supply (it's called B+5 in beasley's version as well) and use that to bias the FET?

Read the bias instructions carefully. You may have to adjust both resistors in the divider to get the Vdd and the bias, and the FET bias (current draw) will affect the V1 plate voltage.

Got it, thanks! Will try to get the basic amp running first and add all the relais later. Fingers crossed!

[captaincoconut]

The schematic in the OP shows +9V but I don't see where the 9V are actually coming from.

Check out this listing I.pdf for FET voltages and waveforms. Whatever voltage you get on the V1 supply you can adjust the voltage divider at the FET filter cap to get the Vdd that you want. https://ampgarage.com/forum/viewtopic.p ... 91#p211891

Okay, looking back at the schematic I just now understand that the divider in the upper left corner is used to bias the FET circuit.

[martin manning]

Okay, looking back at the schematic I just now understand that the divider in the upper left corner is used to bias the FET circuit. :oops:

That divider creates the supply voltage "B+6" for the FET. The supply voltage will affect the bias, but mostly it is set by FET's source resistor.

[captaincoconut]

Okay, looking back at the schematic I just now understand that the divider in the upper left corner is used to bias the FET circuit.

That divider creates the supply voltage "B+6" for the FET. The supply voltage will affect the bias, but mostly it is set by FET's source resistor.

Of course, sorry.

[jazzbass]

Hello everyone,

I would like to build a SSS 005 without Reverb and FET, I do not use the FET input and I do not use the reverb because I would like to put an Eventide H90 in the Send-Return.
What should I cut from the schematic and/or layout?
Obviously a picture is worth a hundred words and I would be grateful if you could have a simplified schematic/layout.

Thanks
Franco

[Guy77]

Something I just noticed about the reverb circuit in this amp is the 120pf cap across the 220k reverb out to ground signal.
I attached a pic here showing it.

Capture.JPG

Its not mentioned but I believe this preforms the same function as placing the .01uf cap across the Reverb Return pot as seen in the JM/Wonderland circuit. This would make this cap a very important part of the circuit and something you dont want to leave out.
We could also therefore change the value of this cap to change how we like our reverb to sound.

Cheers
Guy

[captaincoconut]

Something I just noticed about the reverb circuit in this amp is the 120pf cap across the 220k reverb out to ground signal.
I attached a pic here showing it.

Capture.JPG

Its not mentioned but I believe this preforms the same function as placing the .01uf cap across the Reverb Return pot as seen in the JM/Wonderland circuit. This would make this cap a very important part of the circuit and something you dont want to leave out.
We could also therefore change the value of this cap to change how we like our reverb to sound.

Cheers
Guy

The corresponding schematic in the first post shows different values: 220k and 2nF. There are other discrepancies between the schematic and layout as well, for example the wiring for the phase inverter tube is wrong in the layout, but correct in the schematic (The layout shows the 820R leg wired to the grids (pin 2 and 7 if we follow the classic 12AX7 pinout), while it should be wired to the cathodes (pins 3 and 8 ). There is a handful of other discrepancies, not necessarily errors, though. I noticed that while following the schematic and layout while building my own #005.

[beasleybodyshop]

Something I just noticed about the reverb circuit in this amp is the 120pf cap across the 220k reverb out to ground signal.
I attached a pic here showing it.

Capture.JPG

Its not mentioned but I believe this preforms the same function as placing the .01uf cap across the Reverb Return pot as seen in the JM/Wonderland circuit. This would make this cap a very important part of the circuit and something you dont want to leave out.
We could also therefore change the value of this cap to change how we like our reverb to sound.

Cheers
Guy

The corresponding schematic in the first post shows different values: 220k and 2nF. There are other discrepancies between the schematic and layout as well, for example the wiring for the phase inverter tube is wrong in the layout, but correct in the schematic (The layout shows the 820R leg wired to the grids (pin 2 and 7 if we follow the classic 12AX7 pinout), while it should be wired to the cathodes (pins 3 and 8 ). There is a handful of other discrepancies, not necessarily errors, though. I noticed that while following the schematic and layout while building my own #005.

Yes there are some errors in the layout. I drew the schematic first

[beasleybodyshop]

Feel free to post any errors here and i'll get around to correcting them and updating the layout.

[captaincoconut]

Feel free to post any errors here and i'll get around to correcting them and updating the layout.

Once I've finished my 005 build I will post a layout and schematic of my amp. My build is 95% the same as yours, so the differences should be easy to point out. Just give me a few weeks more time. Maybe I could make a layout that also shows the differences to what we know about the Amplified Nation version of 005?

I want to thank you again for all the work you've done researching the amp.