Overdrive Reverb/Steel String Singer Hybrid

[Reeltarded]

Better even would be a MOSFET. But that would make the amp the Solid State Singer.

I swear.. this MUST become someone's faceplate.

[martin manning]

Yea, I had to laugh too... Good one.

[beasleybodyshop]

Well, I've been plugging away at this again, and revised the schematic to acommodate my tweaks. The amp is about 90 percent built, just need to do a final circuit audit and finish up connections:

Pegasus Schematic10.22.23.pdf

[beasleybodyshop]

I forgot to implement the 2MA "Clean Master" from ODR#60. Will add that at next revision. Probably important.

[jelle]

Cool project! There are no SSS elements in this amp. I have looked in to this closely a few years ago, but the reality is that Overdrive and SSS technology cannot coexist in the same amp. I wish it was possible....but its not.

[beasleybodyshop]

What uniquely defines a SSS?

[Aaron]

I’ve been doing a similar build for the 10 months. But with tube buffered loop, left/right return into 2 x 50 watt power amps. Only 12 valves in total!

Thanks,
Aaron

[beasleybodyshop]

Progress

[WhopperPlate]

Progress

Very cool !

I finished a build like this last year . Essentially ODS with SSS power amp . No filters or reverb . It was one of two prototypes for a client.

The results were predictable, a clean linear sounding response . Overdrive has a powerful clear and rich tone , but overall not nearly as forgiving to play as a typical LTPI setup. It could punch you across the stage.

With the other prototype I made we left out the SSS power amp. Client chose that amp . Said it felt more like an “old man’s amp”. The linearity of the other one was just too unforgiving for his style of playing .

Fwiw

Looking forward to hearing your results!

[beasleybodyshop]

I found this from a post that Max provided on the Todd Sharpe Dumble as well:

""... Description

Dumble Overdrive Special 150 Watt which Mr. Dumble built for Todd Sharp in the second half of the eighties. Mr. Dumble made only very very few of these amplifiers. Indeed only this single specimen seems to be still in existence. The sisteramp #120, also made for Todd Sharp, has been stolen long ago and never reappeared up to now.

The overdrive section of the preamp is very sophisticated. The overdrive tube is a 7247 and not a 7025 as usual. This amplifier has four (staggered) pots to control the Overdrive: trigger (silver ring in the "level" location), taper (Marshall-like knob in the "level" location), level (silver ring in the "ratio" location), and ratio (Marshall-like knob in the "ratio" location).

Trigger adjusts how much of the scale of signal is fed into one triode of the overdrive tube. Level adjusts how much of the signal is fed into the other triode of the overdrive tube. Taper adjusts the scale of high frequencies in the overdrive section. Ratio adjusts how much of the overdrive circuit's signals is fed back into the preamp circuit.

Especially because the Overdrive tube is a 7247 (two different triodes with different characteristics in one tube) these four pots provide an extremely useful control of the harmonic content in order to fine-tune the overdrive circuit's voicing.

So you can adjust the overdrive section for a vast spectrum of tonal colors that by far exceeds the possibilities of a normal Overdrive Special. It's really amazing.

The reverb section is similar to the reverb section of a Steel String Singer. The send and return controls make possible the perfect blending of the reverb signal and the dry signal in a way that adds a warm singing tone to a huge clean or overdriven guitar tone.

The tremolo has a wide range of operation from very slow (the Ry Cooder tremolo) to very fast . It is extremely useful to achieve beautiful textures for all sorts of Blues and ballads together with the sophisticated reverb.

The power amp is similar to a 150 W Dumbleland (same transformers), but the phase inverter and driver tubes both are 7025s as in a Steel String Singer. The output power can be switched from 150 Watts to 75 Watts. The output impedance is switchable to 4, 8 and 16 Ohms. The original footswitch provides the possibility to switch on and off the overdrive, the preamp boost, the reverb, and the tremolo. Because this amplifier is heavy due to its giant transformers and the huge amount of electronic parts inside, the bias and the dynamic balance can be measured and adjusted the way an Ampeg SVT or V9 can be adjusted.

As you see this amplifier blends the qualities of a very sophisticated version of the Dumble overdrive circuit with the harmonically extremely rich, huge and mighty clean sounds of the Dumblelands and Steel String Singers. So maybe this is the ultimate and for sure the most versatile Dumble amp. You can't imagine a tonal color that cannot be achieved with this wonderful musical instrument. There is a signal path diagram of this amplifier on page 730 of the 4th edition of "The Tube Amp Book" by Aspen Pittman.

Preamp tubes specified by Mr. Dumble are 6 x 7025, 1 x 7247, 1 x 5751
Poweramp tubes specified by Mr. Dumble are 4 x 6550 or 4 x KT88 ..."

Source: http://thesubjectmatter.com/dumblearchi ... efault.htm

AFAIR Alexander Dumble once commented: If you turn off the OD, it's a SSS.

Cheers,

Max"

interested to try a 12DW7 for the OD section.

[jelle]

Right, a buffered phase inverter, does not make it a SSS, Dumble called this amp that Max describes, an Overdrive Special amp, and it has post phase inverter buffers.

Also at least one Dumble SSS amplifier does not have the post PI buffers. So....having the post PI buffers do not instill amplifiers with SSS DNA nor is it required to make it a SSS, its more complicated than that.

very cool amp BTW!

[beasleybodyshop]

So what elements of an amp make a SSS?

[ViperDoc]

I'm curious to know this as well: what makes it a SSS amp?

This blended design looks very interesting, I hope you'll include a tone report with examples when ready.

From what I can gather, the Steel String Singer (based on SSS #002) is a single-channel clean amp with the following observations (and if you don't have a grain of salt ready, please go get one ):

1) dual-triode, low plate preamp (100K)
2) V1A cathode positive feedback (?) to the V1B plate with cathode tail resistor
3) no mid boost or preamp boost
4) deep switch a la ODS classic
5) stepped EQ filter hi and lo pots
6) V1B cathode LNFB loop with the first post-filter CF with cathode tail resistors
7) CF reverb and transient signal mixing
onboard tube-driven spring reverb
9) lower value capacitor power supply (100-100 series vs. 330-330 series i.e.)
10) post-PI cathode followers before output section.
11) no cap around the bass pot
12) 100-150-200W power section for skyscraper headroom (break the windows before break-up)
13) Fender-ish pot, cap and slope values.
14) Master Volume "mid boost".

You explained it was your intention, but your preamp looks like an ODS preamp to me with all the boosts; you've omitted the preamp LNFB and PFB loops; OD and Filter sections, Reverb and an effects loop, and some cool switching for all that is also added. Does adding the EQ filter and reverb bring it towards an SSS? From the front, I'd sure as hell say it does. I've read the post-PI CF stages really help highlight a player's weakness in technique, so I'd be interested to know how the OD section changes that or not. That's all my untrained eyes see at the moment.

[beasleybodyshop]

Viperdoc,

Thanks for kicking that off. Seems like a lot of things define the SSS. And yet all of the SSS amps are different; some are very different from each other. I've heard dumble even reference it as a mod even in the 80s guitar player interview. So doesn't seem like it's any one thing, or even any two things. The only thing that is consistent between them is they appear to be single channel amps with at least 85W of power (Twin iron will not get you 100W).

I've only ever seen step filters on a SSS. Maybe a Dumbleland used them too? Yeah I think so. But in Dumble's own words and literature the SSS seems to be voiced for guitar. So long as I don't like the sound of a bass plugged into it...tick that box. Lol.

Reverb circuit is not consistent. Few different types in the various versions. Fender style, Dumble 3 tube style, etc. Ok. This circuit has that. Check that box too.

Post PI driver - most SSS and iIRC all the Dumbleland variants had them. AC coupled or DC coupled. SSS can have either. Or none. So box checked there too.

Local NFB in preamp - both ODS and SSS variants have those. Various degrees of each scattered throughout. Box checked.

Did all SSS have Deep/Jazz/Rock/Mod/Bright switches? Does having any of those features, or none of those features factor into the name?

You can pretty easily surmise a Venn Diagram of things that overlap. And in my mind, adding step filters and some sort of post PI driver, makes any dumble derivative build *more like a SSS* than not having those.

I guess if I physically switch out the OD circuit, it's more like a SSS. So not always an ODS? So I guess its a gender fluid issue? Pan Sexual?

As far as post PI CF driver, whoo boy, I would agree it's unforgiving. Not for the hamfisted. Let me tell you though, as a Pedal Steel guy, it is lovely. Vastly improves what most PSG folks dislike about tube amps. Not a traditional Steelers, but Daniel lanois used to play his steel through an SVT. Is an SVT a SSS?

And then there's the silver alligator SSS, that has a pair of EF86 pentode tubes, tremolo and reverb. Is that not a SSS? Does the faceplate have to say SSS for it to be one? On this build, there is no name on the faceplate, so I think I'm OK

[WhopperPlate]

As far as post PI CF driver, whoo boy, I would agree it's unforgiving. Not for the hamfisted. Let me tell you though, as a Pedal Steel guy, it is lovely. Vastly improves what most PSG folks dislike about tube amps. Not a traditional Steelers, but Daniel lanois used to play his steel through an SVT. Is an SVT a SSS?

According to Bruce Egnator : look inside SRV SSS and it is a ampeg SVT with the preamp rebuilt .

And if you look inside of an SVT what will you find ? Lots of Draloric resistors …right Jelle? Lol

Based on the above discussion , all I can safely conclude on what defines a SSS is strictly clean voiced amplifier with step filters and reverb .

Beyond that ; it’s just one guy naming his creations. No use in getting fixated on what he called an SSS without a post phase inverter cathode followers, or if 121 is an ODS with SSS features or a SSS with ODS features . It just is a thing and has a sound and he happened to call it by whatever . Obviously Dumble was rather loose in the end with what falls under what .