Located in Portland



A used THD Flexi 50 Amp and THD Hot Plate Attenuator in Excellent condition with Foot Switch, Carry Bag and Rack Mount Kit.  See below for more details and specifications.


The Flexi-50 is a precision hand-built 50-watt Class-AB amplifier with foot-switchable overdrive/boost, foot-switchable master volume control and the ability to use almost any preamp and power tubes in any combination, including 6L6, EL34, 6V6, 6CA7, 8417, 6550, KT66, KT77, KT88, KT90, KT100, EL84 (with Yellow Jacket adaptor), 6K6, 6F6, 12AX7, 12AY7, 12AU7, 12AT7, 12AZ7, 12DW7, 12BH7, ECC83, ECC82, ECC81 and many more, giving the user a huge palette of available sounds simply by changing tubes.

The amplifier has a fat, clear, full clean sound reminiscent of late 1950s to early 1960s American combos, and overdrive to rival the best British heads. Even at the highest overdrive settings, the amp still demonstrates dramatic touch sensitivity, cleaning up very well when the volume on the guitar is reduced. Additional features include external bias test points and individual bias controls, permitting the user to quickly and accurately set the output tube bias with any digital voltmeter. The dual bias controls permit the user to correctly bias even mismatched tubes, eliminating the need for matched power tubes.

In the Flexi-50, we at THD have brought together an ideal combination of simplicity and flexibility, hence the name "Flexi-50". Why strive for simplicity? Robust design and construction are among the reasons. Ease of use is another prime reason. We hear every day from guitarists who have purchased 3- and 4-channel guitar amplifiers, only to discover that aside from varying gain levels, the channels all sound, (and equally importantly,) feel more or less the same, dashing their dreams of flexibility to pieces. Another byproduct of an overly-complex amplifier is that it can take a very long time to uncover a sound that really works for you.

Switch from an over-wound bridge pickup to a clearer, lower-output neck pickup and suddenly the amplifier responds very differently. Our input is quite sensitive to the individual impedance curves and inductance characteristics of your pickups, so you will not experience the all-too-common situation where every guitar you own sounds the same through your amplifier. PAFs sound like PAFs. Strats sound like Strats. Filtertrons sound like Filtertrons. Lipstick pickups sound like, well, like nothing else on the planet. Into exotic handmade guitars and pickups? Wouldn't it be nice to have an amplifier that lets you hear the difference between 9000 turns and 9200 turns of wire in a pickup? Come plug in and see (and hear) for yourself.

Switching tubes is easier than ever before. With the built-in bias adjustments, you can easily and accurately set the bias in about 20 seconds, even with two completely different tubes.

Other features include a line-level effects loop and a 50-watt/20-watt switch right on the front panel, letting you drop the plate voltage on the power tubes from 475 to 325, giving not only lower output, but also smoother, more even response and even longer tube life. We also have a series/parallel switched impedance selector that can take any cabinet from 2 ohms to 16 ohms impedance, and always uses 100% of the transformer windings all of the time, another THD innovation. This assures you a full, even output sound, regardless of the impedance setting. The power and output transformers are fully shielded to assure that hum and noise are kept to an absolute minimum, and that pickup-feedback from transformer coupling is all but eliminated.


Year : Used
Model : THD Flexi-50 Amp Head and Hot Plate Attenuator
Case : Carry Bag
Condition : Excellent