Steel String Singer+Overdrive Reverb+Post PI Cathode Follower Hybrid thread

[beasleybodyshop]

Hello everyone!

I have been hard at work trying to kludge together a bunch of those cool Dumble ideas into one amp. My goal was to make something that was somewhat like a Steel String Singer with Martin's step filters, low plate OD channel, and post phase inverter cathode follower using Martin's improved cathode follower driver circuit. I will also use the Metroamp solid state FX loop, which uses a pair of LND150s as a buffer and return stage.

Note that the clean preamp is more ODS based, and without Jazz setting or PAB. I did integrate the preamp from an Echoplex EP3 in lieu of the normal D style FET preamp.

I opted (for space reasons) to run a pair of 6550s at around 100W as opposed to a quad of 6L6s.

Inevitably there are some compromises - The step filters are plate driven, followed by a cathode follower - mixer stage in a SSS amp. In trying to keep this thing from using 8 preamp tubes, I've opted to move the filters to the end of the circuit before the send on the loop - The idea that the loop's buffer will play double duty for FX and for the filters - then the return of the loop exits to the top of the master volume control.

I've tentatively wired in a loop bypass relay on the schematic, but that might go away when i build it.

I would love to have some feedback here from the group on this schematic. I've attached it below. I've also got a layout pretty well underway

Let me know what y'all think

Dustin

SSS Hybrid TAG.pdf

[Guy77]

Excited to hear how this sounds when its done!
I don't see were the signal goes through the 1M resistor and then the 68 K ( or slightly higher like 150K) to ground.
This comes off of v1B in the SSS/JM amp. Maybe this is not being used since you are incorporating the OD channel?

Edit. Ok I think I see it now, its actually 470K on the SSS amp and not 1M and then you have the signal going into v5a.

Cheers

Guy

[dreric]

This looks like a great project. I'd love to see the lay out.
Eric

[tictac]

Your reverb send could end up with too much gain since your feeding it after V1B (series) instead of before it (parallel) as Dumble does....

TT

[dbeasley]

Tictac,

I am borrowing heavily from the JM Sig amp for the clean preamp and some of the reverb. I know on the SSS it's taken from after the first stage, and on the ODR/JM Sig amp it's after the 2nd gain stage.

I'll leave some space to play around with it both ways when I start to build it.

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[tictac]

The JM Sig schematic posted on TAG shows the reverb being tapped before the 2nd stage. We are talking about the TwoRock amp, correct?

TT

[dbeasley]

Sorry, I should clarify!

Topology wise, this amp looks a lot like Overdrive Reverb #60. The verb entrance comes after the clean channel OR the OD channel, unlike the other Dumbles that don't have an OD channel. I used JM sig amp preamp values in the clean channel. OD channel is a lot like #60.

I built a version of ODR#60 with the clean channel of the JM sig amp and it sounded absolutely killer. This schemo is building upon those ideas, and implementing the cathode follower/filters from the SSS.

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