Doppler Stereo Combo


The Doppler Stereo Combo expands sonic dimension with an original design Asymmetrical Frequency Soundstage
dividing higher and lower frequency ranges into a 10" and 15" speaker.
The V-front cabinet delivers a Doppler Effect pitch-shift Vibrato with a Leslie rotating speaker sound in Stereo.

The all-tube circuit is musically balanced around interactive control knobs, retaining the original sound quality and character of the instrument at the input.

Stereo pitch-shift Vibrato

Asymmetrical Frequency Soundstage ™

Stereo Leslie rotating speaker effect

Handwired point to point terminal wiring

Octal preamp tubes

Versatile, interactive controls

4-band EQ

Transformerless Reverb

True bypass Master Volume

Variable speed foot control

Illuminated Front Panel

No-compromise Custom Transformers
by Mercury Magnetics

Highest quality NOS components

Guitar - Steel - Keyboard - Bass - Harp

Available in 18, 36 and 75 Watt power output versions.

Class A push-pull 18 Watts 6V6/EL84M
Class A push-pull 36 Watts KT66/EL34
Tube rectifier 5AR4/GZ34
Class A push-pull 75 Watts 2x KT66/2x EL34
Solid-state rectifier
Octal preamp tubes 6SL7 and 6SN7
Remote variable Speed pedal
Remote Reverb On/Off footswitch
Volume, Reverb Mix/Dwell
4-band EQ
Fast and Slow speeds
Speed, Intensity, Master Left/Right
Sprague Vitamin Q paper/oil tone capacitors
Carbon composition resistors
Sprague ATOM TVA filters
Point to point terminal cloth wiring
NOS tube sockets
Powder coated Aluminum chassis 12 ga.

Tone Tubby Hempcone and Weber speakers

100/120/220/240VAC (50/60Hz)
Handmade in USA

Solid pine cabinet construction
Removable casters

Large: 33.5" wide X 21" tall X 9 to 11.75" deep
Weight: 70 lbs.

Small: 22.75" wide X 17.5" tall x 7.5 to 10" deep
Weight: 52 lbs.

Covered cabinets are individually custom made to order from solid pine and your choice of color, grill type and handle.
Ask for samples of available covering and grill cloth.

The example shown has black leather and alligator tolex with black/tan/gold grill, brass vents
and a custom made steel-reinforced genuine leather handle with alligator print.

The Doppler Stereo Combo is entirely hand-built, using the best-sounding NOS caps and resistors.
Terminal point-point wiring is the same technique used by the military and in aviation construction for reliability.


Octal preamp tubes have a wider tonal spectrum and sound more relaxed and revealing with less compression than later 9 pin versions.
The transformerless Reverb design, provides extra rich harmonics and reflections.
The stacked control knob provides Mix and Dwell settings from no Reverb over subtle swells all the way to huge endless Reverb only.

The 4-band EQ covers an extended frequency range from rich, fat, warm to bright, thin and chimey tonal ranges.
The Master Volume is true-bypass when turned all the way up.


With this asymmetrical frequency vibrato we can hear the full frequency spectrum and original quality of the signal without the phase-canceling signal loss of a typical symmetrical vibrato.
The Vibrato controls are a Fast and Slow speed switch, pulsing tempo LED, Intensity and Speed controls, creating a variable-speed stereo pitch-shift vibrato from subtle chorus to heavy pulsing vibe.
A remote Speed footpedal gives variable speed control with a Vibrato On/Off switch.

Power Amp

The asymmetrical frequency power amp separates the signal into upper and lower frequency ranges and plays them in stereo.
The KT66 and EL34 power tubes can be switched with a toggle to feed either 10" or 15" speakers.
Each speaker has it's own Master Volume on a stacked knob.
The custom output transformer has a special design, perfectly balancing KT66 and EL34 tubes while giving musical even-order harmonic break-up and an enhanced wide frequency range.


18 Watts:
12" Tone Tubby Key West Alnico hempcone.
8" Tone Tubby Humboldt Alnico hempcone.

36 Watts:
15" Weber 15A200 - a Jensen Alnico P15LL woofer version as used in vintage Leslie rotating speaker cabinets.
10" Tone Tubby Silver Bullet Alnico hempcone.

75 Watts:
15" Weber 15A200 - a Jensen Alnico P15LL woofer version as used in vintage Leslie rotating speaker cabinets.
10" Tone Tubby Red Alnico hempcone.

An audiophile grade custom-made crossover with air core coils and paper/oil capacitors divides the speakers into their respective frequency ranges.

Sound Experience

The warm laid-back omni-directional lower frequencies of the KT66 and slower 15" speaker provide the foundation and background of the soundstage, with the brighter and lighter directional frequencies from the EL34 and faster 10" speaker floating on top and into the foreground.

The stereo spread of frequencies let the ears experience a 3D effect with notes and harmonics continuously relocating in real time depending on their pitch. This effect is enhanced when fingerpicking, giving an impression of two individual instruments playing.
The stereo imaging is further balanced with pickup selection on the guitar, EQ settings on the amp or a Wah pedal.

Playing full chords gives a sense of expanding dimension surrounding the player and listener with soundwaves from all angles as they get reflected inside the room.

With increasing Vibrato and Reverb the sound turns into a phase modulating echo in 3D stereo, acquiring an organic-like liqui sound character from slow motion chorus to jitter vibe.

An electric psychedelic experience induced by tubes and acoustical physics alone.

NEW - Small Cabinet 18 Watts with 12"+8" speakers

Panel Controls:

Input, Volume, Reverb Mix/Dwell, 80 Hz, 400 Hz, 1500 Hz, 5000 Hz, Fast/Slow, Speed, Intensity, Master Left/Right, Tubes/Speaker Switch, Power/Standby Switch

1/4" Jack for external Speed and On/Off pedal

Illuminated control panel - click to enlarge


18 Watts: 4 x 6SL7, 6SN7, 6V6, EL84M, 5AR4/GZ34

36 Watts: 4 x 6SL7, 6SN7, KT66, EL34, 5AR4/GZ34

75 Watts: 4 x 6SL7, 6SN7, 2x KT66, 2x EL34

Vintage NOS and new production tubes. Ask for Premium Tube Upgrades for the ultimate tone experience!
Ceramic sockets with gold pins are available as a custom option.

Wide Gold Arrow Knobs, Steel reinforced raised Leather Alligator handle

Sound Samples:

Zane Carney Demo with
Suspense guitar.

Sound clips are in stereo with 15" speaker on the left and 10" speaker on the right.
These are raw tracks without editing or effects.

The guitar is the Suspense
For the 10" speaker microphone I upgraded a large diaphragm condenser tube mic with a Micro Tube, Neumann U47 replacement capsule and Jensen transformer plugged into the Octal Simplex Vintage Mic Pre
The 15" speaker has a Shure SM57 into the Micro Tube Simplex Mic Pre

15 - EL34 | 10 - KT66 - 15'' speaker with EL34 and 10'' speaker with KT66

15 - KT66 | 10 - EL34 - 15'' speaker with KT66 and 10'' speaker with EL34

15 - EL34 | 10 - KT66 Vibrato - 15'' speaker with EL34 and 10'' speaker with KT66 with Vibrato

15 - KT66 | 10 - EL34 Vibrato - 15'' speaker with KT66 and 10'' speaker with EL34 with Vibrato

Dreams - various guitar pickup and speed pedal settings in Slow speed mode with moderate Intensity and mild Reverb

Ripples - steady Fast speed with strong Intensity and moderate Reverb

Echoes - various guitar pickup and speed pedal settings in Slow speed mode with strong Intensity and Reverb

Rainy - steady Slow speed with mild Intensity and moderate Reverb

Gypsy - mild overdrive and steady Slow speed with moderate Intensity and Reverb

Asymmetrical Frequency Soundstage is a trademark of Siegmund Guitars & Amplifiers