$2400 Model-T6 (130 W tube amplifier for bass / synthesizer) ? FOR SALE
This amplifier is truly unique, as it is a totally rebuilt old Sunn head, only leaving the original transformers and a few of the user controls as original components. All new wiring, tube sockets, high quality components, custom design based on the Model-T but with signal routing improvement, power supply noise reduction, and an expanded 6-position MID-FREQ whereas the original Model-T only had 3 frequencies. It comes with a 30 day guarantee, and a 9-page manual that includes: instructions; photos; specs, block diagram, schematic with test points.
Based on Sunn Model-T (2nd gen.) with updated features and improvements
You can see and hear a demo on YT at:
https://youtu.be/SH79XUx5GkMI have this amp currently on consignment at Centaur Guitar on NE Sandy Blvd. in Portland, Oregon.
HIGHLIGHTS:
? Original Sunn 1200s chassis converted to improved and feature updated Model-T design
? 130 Watts, 4 Ω and 8 Ω outputs
? Vacuum Tubes: (3x) 12AX7, (4x) 6550 tubes
? Point-to-point wired using no printed circuit boards
? 6-position mid-range frequency select, switch
? Tone shaping prior to gain circuit provides improved and enhancing dynamic and tonal response of both clean and overdrive settings
? Bass guitar and keyboard/Synth inputs ? Synth input includes high-pass 57 Hz filter to help reduce subsonic frequencies
? New components, including terminal strips, wiring, tube sockets, jacks, etc. (1200s original transformers, choke, knobs)
? Dedicated DC filament supply for pre-amp tubes to eliminate hum induced through pre-amp tubes stages
? Star-ground return paths which reduces ground-current induced noise
? Solid-state rectifier diodes for higher power output and improved reliability
? Adjustable bias and hum-balance accessible without removing chassis from case
? Comprehensive 9-page user manual including System Overview, Bias, User Instructions, many photos, aerial overview of major components, Specifications, Block Diagram, Schematic with test points
SUMMARY:
This is a rare and unique vacuum tube bass amplifier primarily based on the Sunn Model-T, inside of a late 60s Sunn 1200s chassis. Hand-built by myself, a hardware engineer with 30 years experience, including 20 years servicing vintage tube amps and a vast array of pro-audio equipment. It features point-to-point wiring, new components* (see section below), bass (instrument) and keyboard/synthesizer (line level) inputs, a 6-position mid-freq tone select switch that is road worthy and great for studio recording due to the exceptionally low noise floor provided by star ground wiring and DC filaments for the pre-amp stages. It also has the signal path rerouted from the original Model-T to establish the tone circuit prior to the first gain (drive) stage, which greatly improves dynamic and tonal
characteristics for both clean and overdrive signals.
COMPONENTS, WIRING, etc.:
New, high quality components include jacks, tube sockets, resistors, capacitors, inductor (for tone circuit), terminal strips, and wiring. The only original components from the 1200s are the main and output transformers, PS choke, switches, knobs, and some of the potentiometers.
INPUTS:
Inputs for both bass guitar and keyboard / synth (line level). The lower ?Synth? input provides a high-pass cutoff of around 57 Hz.
SPEAKER OUTPUTS:
130 Watts RMS
4 Ω and 8 Ω speaker outputs. Note there is a 16 Ω tap from the output transformer (original to the 1200s) that is unconnected--however this can be connected to one of the two output jacks that are currently connected to the 4 Ω and 8 Ω taps.
LINE OUTPUT: The Line Out is a 1/4 inch jack. The signal is derived from the speaker output (attenuated to line level), and has a level control.
TONE CIRCUIT:
A 6-position switch adds 3 more frequencies to the mid-range tone stage, allowing for a much more versatile tonal characteristic than the 3-position switch of the original Model-T design and the majority of bass amplifiers in existence.
POWER SUPPLY (Low-noise design):
DC filaments for the pre-amp stages, star-ground wiring, and high quality capacitors throughout the power supply provide exceptionally low noise throughout. Solid-state rectifier diodes maximize the available output power and headroom, reduces the long-term maintenance cost, and increases reliability.
BIAS and HUM-BALANCE:
Bias and hum-balance accessible from the top side of chassis without having to remove the chassis from the case.
TESTED:
I have played dozens of gigs with this amplifier and it has been reliable, sounds beautiful, and has a very diverse range of tone for a wide variety of bass guitars and styles. I have also used it for recorded sessions and sounds wonderful.
DOCUMENTATION:
I created a 9-page manual, including description, photos, mid-range 6-position frequency response chart, specifications, block diagram, and the full schematic which has AC and DC voltages as test points.
GUARANTEE:
This amp is sold with no refunds. However, I will guarantee this amplifier for a full 30 days from sale, by providing technical support (repairs) as long as the amplifier is matched to either an 8 ohm or 4 ohm speaker load. Vacuum tubes and the transformers are not covered. Only defects of the amplifier not brought on by external problems are covered. For example, I will not cover this 30 day warranty for things such as wrong speaker impedance, amplifier being dropped, cable being pulled hard while plugged in (accidental tripping on guitar cable), wrong speaker cable type used, spills of any liquid, food, or foreign substances into the amplifier. Excess humidity (such as a wet / damp garage, basement, or practice space that has humidity issues). Animal or insect contamination of any kind.
NO TRADES.
WHERE TO CHECK OUT THE AMP:
You are welcome to come check out my amplifier on consignment at Centaur Guitar (on NE Sandy Blvd.)
Centaur Guitar hours of operation are:
Sun - Mon..... Closed
Tues - Fri...... 11 AM?7 PM
Saturday........ 11 AM?5 PM
