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

[norburybrook]

I noticed that compared to #1,2,3,4 this amp has one pre amp tube less. Why is that? I presume it's a single rather than dual tube reverb, yes, no?


M

[mojotom]

I noticed that compared to #1,2,3,4 this amp has one pre amp tube less. Why is that? I presume it's a single rather than dual tube reverb, yes, no?


M

Yes it seems so. More Fender style reverb (2 tubes) rather than 3 for others SSS.

[Charlie Wilson]

It looks like there is an extra filter and connection for the reverb driver B+ that is missing on the layout. It is usually gooped to the chassis. Typically the red tap of the reverb driver is B+ and the blue is the plate. I don't know if that matters.
CW

[talbany]

Marcus

I noticed that compared to #1,2,3,4 this amp has one pre amp tube less. Why is that? I presume it's a single rather than dual tube reverb, yes, no?

Yes this is comparable to the AB763 Blackface 2 tube plate driven reverb ( w/220K mixers). It's OK if you like just a touch of reverb in the mix however it doesn't have nearly the gain/drive/frequency response thats as lush and full sounding as #002 that has the "Tweed Mixer" low impedance send which has 4 total (reverb and mixer) Out of all the reverbs attached to the SSS model this one for me (and many others) is one of the best sounding reverbs ever hung on the back of a guitar amp.

IMO the 763 version is a sub par circuit that has it's problems.
Tony

[beasleybodyshop]

It looks like there is an extra filter and connection for the reverb driver B+ that is missing on the layout. It is usually gooped to the chassis. Typically the red tap of the reverb driver is B+ and the blue is the plate. I don't know if that matters.
CW

That's my bad again. I meant to delete that filter node. I took my schematic from another SSS project as a topographical "template" and omitted and added things as I made notes.

FWIW, this reverb is 90% like a classic Fender AB763 with the added benefit of a Dwell control and LNFB to keep it from breaking up early if you run a particularly hot signal. This being said, still pretty easy to get lush and/or super wet drippy spring reverb sounds (based on the #005 clones I referenced this from) so you have plenty of drive from the reverb circuit here. It sounded great and didn't give the impression it was lacking anything. I guess if you think a blackface fender reverb sucks you would feel the same way about this amp. Either way, it sounded pretty amazing with a Lexicon rack reverb set to Large Plate my client had laying around

[Charlie Wilson]

So just to be clear here. You are saying that the reverb does not need the extra filter? I see that cap gooped to the chassis in both the Bludotone and Amplified Nation versions of it.
CW

[martin manning]

DSB, if you are updating the layout, I see some missing cap values, reversed diodes, and an error in the ground connections in the bipolar supply. I'd do it like this.

[beasleybodyshop]

Thanks Martin! Thats a pretty important error. I'll update the layout with those corrections and repost.

[beasleybodyshop]

Charlie,
My iteration of the design doesn't need that filter by the reverb driver, because I'm using a bipolar supply derived from the bias winding to drive the post PI cathode follower, and im not using a quad of 220uF 350v caps in series-parallel configuration like the original 150w version has. I'm able to fit all the single caps on the board, and just do with the single cap can by the chassis.

[martin manning]

Thanks Martin! Thats a pretty important error. I'll update the layout with those corrections and repost.

BTW, I would also run that ground back to the PT CT ground.

[rootz]

I couldn't help myself during these boring self isolation days and crossed his #005 design with an ODS. Frequency response is predicted to be very close to the original #124 (compared in the graph). The extra triode would add some 2nd harmonics to the base tone of the #124. This is by no means meant to be a clone of a #124 with added reverb. It's a #124 with a modded Fender reverb of sorts. Should be fun and would build if money were plenty right now. Some day, some day!

[rccolgan]

@rootz - Wow. that's some amazing LTSPICE work there! I've been meaning to draw up SSS #002 & #004 for comparisons in LTSpice for frequency response curves

[beasleybodyshop]

That's awesome Rootz! Thank you for sharing this. Is this taking into account the high value NFB resistor as well? I've seen anywhere from 220K-100K NFB resistor value for some of these #005 clones.

[Roe]

the #005 transformers seem to [not] be from a Peavey Deuce/VT 120 - (370VAC; 2k3 primary impedance). Instead of a choke, HAD tended to use a 500R resistor (should be 10w or more)

[norburybrook]

the #005 transformers seems to be from Peavey Deuce/VT 120 - (370VAC; 2k3 primary impedance). Instead of a choke HAD tended to use a 500R resistor (should be 10w or more)

That's exactly what I used for my JM wonderland build. You have to use a FWBR though which gives you around 500vDC on the plates. I noticed on the peavey power board they used a resistor instead of a choke too.....cheapskate

M