*Original Dumble Steel String Singer amp no. #002 - photo from jacksonampworks. Currently owner is John Mayer.

Dumble Steel String Singer history

Steel String Singer is the most famous Alexander "Howard" Dumble  amplifier. It's currently the Holy Grail, as Mr. Dumble made only #12 of this model. The amplifier was originally designed for Henry Kaiser  (#001), but Mr. Dumble actually started working on it in the late 1960s. It comes from the design of Dumbleland, which was created in 1966. The purpose of Mr. Dumble's goal was to create a very loud "clean" amplifier that would not distort even at high volume levels. Dumbleland amp had 4x 6650 power tubes and generated 150W RMS. Mr. Dumble made only #10 of this model. It was used by Stevie Ray Vaughan  and Double Trouble on the album Texas Food (1983). The material was recorded in studio of Jackson Browne, who had a significant collection (including the first Overdrive Special) of Dumble amplifiers. SRV quickly noticed that he liked Dumble amplifiers very much and thanks to Browne he got to know Mr. Dumble personally. SRV then purchased its first SSS and thanks to it the model gained considerable popularity at that time.

*Original Dumbleland Special no. #008 - photo from jimsguitars

*Stevie Ray Vaughan "SRV" with Dumble Steel String Singer and Dumbleland - photo from srvarchive

What is the Steel String Singer phenomenon?

The three most important features that can be mentioned are: crystal clear sound (even at high levels volume); amazing dynamics and the best reverb ever created in guitar amplifiers. That's all and that's all... Mr. Dumble largely used patterns from Fender amplifiers such as the Super Reverb and Twin Reverb models. Therefore, SSS largely refers to the sound of amplifiers of the Blackafce era, which are characterized by a lot of lower range, slightly cut midrange and glassy top. Mr. Dumble wanted to obtain the purest sound possible, which is why it used many solutions that cannot be found in Fender amplifiers.

*Original Dumble Steel String Singer amplifier no. #001 - photo from jimsguitars

Preamp consists of 5 gain stages (double triodes ECC83/12AX7), two of which are reverb stages. On the first stage between triodes there is EQ correction, signal sending directly to reverb circuit and band regulation, which Dumble used for the first time in Overdrive Special model. We're talking about: JAZZ/ROCK; DEEP and also BRIGHT switches. The FET circuit is based on 2N3823 transistor and connected to normal input. It's nothing more than a mini preamp "borrowed" from the ODS model. It imitates an additional preamp tube. Between the first and second stages there is a circuit of RLC filters (resistor/coil/capacitor), implemented by two step potentiometers Hi and Low. Thanks to this simple but very effective solution, in addition to the classic TMB correction (treble/middle/bass), we can cut the band from the top or bottom.

RLC filters by D-TONE AMPS, based on Dumble SSS amp circuit

The second and third stages are a classic signal amplification layout, i.e. cathode follower, plus signal return from the reverb. After summing, signal is send to Master Volume. Here it is worth mentioning the MID switch, which boosts band around 2000 Hz, i.e. high midrange. The first, second, third and half of fourth stage are "connected" to the LNFB (local negative feedback), which significantly affects overall sound of the amplifier. It's purpose is to clean signal from distortion. Some sources say that SSS #4-12 had more LNFB than #1-3, which was supposed to make them even more crystalline...

*Original Steel String Singer inside (photo source unknown)

D-TONE SSS style inside

Reverb is a classic circuit "borrowed" from Blackface era Fender amplifiers. It's based on two amplification stages and a spring module known from the Deluxe Reverb model. Mr. Dumble would not be what it's if it had not made modifications to triode arrangement on reverb tube stages. Thanks to this, he could use two potentiometers, SEND and RETURN, which significantly improved control of obtaining a juicy reverb. It eliminated effect of "muddling" reverb sound, which is the "Achilles heel" of many Fenders...

Spring reverb module by D-TONE AMPS

The biggest change compared to other amplifiers was "dual" inverter. The first tube is a classic phase inverter. The second tube is cathode follower, which is connected directly to grid of power tubes. This treatment is intended to add transparency, clarity and overall "shine" to the sound. Thanks to this, the amplifier sounds stronger and "wider" and also has a unique compression not found in Fender. Only #1-3 Dumble Steel String Singer had this solution. The power supply and power amplifier are a classic push-pull circuit based on 4x6L6 (100W) or 6650 (150W) tubes. Similarly to the Overdrive Special, amplifier doesn't have a rectifier tube. There is a rectifier bridge, which is good solution for a 100W amplifier. In the first SSS, Mr. Dumble used Fender Twin Reverb transformers produced at that time by Schumacher. Perhaps that is why #1-3 sound the most Fender style. It should be emphasized that each Stell String Singer had a slightly different layout, which made it sound slightly different. It's not entirely clear what the differences were, as only #001 and #002 were developed based on photos of the interior of the amplifier. Rest still remains a mystery...

Tube Amp Doctor transformers made in USA used by D-TONE AMPS - best replacement in Schumacher style

To sum up, Steel String Singer is a "real singer" that is difficult to compare to any guitar amplifier. It's in itself a determinant of pure sound and unprecedented dynamics and tube compression. Many consider this the amp with the best reverb. We also confirm this thesis - we compared the SSS reverb with Fender Deluxe Reverb model, which is an icon of this type of sound. Perhaps this may be the most Dumble clone amp.

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*D-TONE AMPS doesn't own of photos - we only shares them and not copy. Original source is under each photo.