Dual bias controls let you complete most tube swaps in less than a minute.

The precision, hand-built, single-channel THD Flexi-50 50W/20W Class AB Amplifier Head can operate loaded with almost any preamp and power tubes in any combination. It's the only amplifier you need to own. Whether you strive for English overdrive, California clean, or Texas punch, this master-class head can deliver it. It also boasts a heady 50W Class-AB operation, footswitchable overdrive/boost, and footswitchable master volume control. Its consistently overbuilt and pristine circuitry ensures dramatic touch sensitivity even at the highest overdrive settings. Its incredible flexibility (the reason it's named Flexi-50) delivers all the sounds and tones you could possibly desire, from vintage purr to modern, high-gain roar.

It has a Lo/Hi input switch; Volume, Treble, Middle, Bass, Master, and Cut knobs; Boost section with separate Gain and Tone knobs, and a wattage select switch (50W/20W).

THD Flexi-50 50W/20W Class AB Amplifier Head Features:

• 50W/20W Class AB amplifier
• Hand-built
• Wattage select switch (50W/20W)
• Single channel
• Footswitchable overdrive/boost and master volume control
• Accepts almost any preamp and power tubes in any combination
• Ships with 3 - 12AX7s (preamp) and 2 EL34s (power amp)
• Lo/Hi input switch
• Volume, Treble, Middle, Bass, Master, and Cut knobs
• Boost section with separate Gain and Tone knobs

If you're serious about pure tube-tone flexibility but hate multi-amp collections then the Flexi-50 is for you. Call or click and make it yours!

THD Flexi-50 50W/20W Class AB Amplifier Head Specifications:

• 15-1/2"W x 8-3/4"H x 10-3/4"D
• 45 lbs.

THD Flexi-50 50W/20W Class AB Amplifier Head

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Average of 7 User Ratings

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Destined For

Posted by Commander Izo from Philadelphia, PA on Nov 13, 2008

Experience w/product: I own it

Reviewer's Background: Gigging Guitarist

Reviewer's Play Style: Rock N Roll

This is, hands down, the finest valve amplifier that I've ever had the pleasure of playing (let alone owning). It is really difficult to describe in words why this amp is so incredible; it has, however, a tone that is all its own (plus you can change the very character of the tone on a whim due to the valve-swapping capabilities). And, said tone is so far beyond anything I've ever played (and I've played a LOT of valve amps), the quality is just so good. The only thing you should be aware of when buying this amp is that the gain is MODEST! That's not good for me. But the thing is, this thing takes pedals like a king, so if the stand-alone gain isn't enough for you, add your favorite pedal(s) and you're good to go. If you're into experimenting with your sound like I am, get this. The options are overwhelming. The workmanship is beyond comparison.

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Tubes done right

Posted by Geo from NY, LA on Apr 11, 2008

Experience w/product: I own it

Reviewer's Background: Pro Studio and touring

Reviewer's Play Style: all

This is one of the best tubes amps I have ever played, and I have played them all.

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Awesome rock amp!

Posted by musicandbananas from Orlando on Jan 21, 2008

Experience w/product: I own it

Reviewer's Background: Active Musician

Reviewer's Play Style: Experimental rock

This is one great sounding amp. I love the british crunch and the bass and mids are incredible. This is a very punchy amp with lots of bass response. I'm not thrilled that it only has one channel, but with the boost and high/lo switching it can take you from the lo setting of clean to the high setting with boost overdrive and makes it simulate a 2 channel amp. I think it sounds better than any other amp I've heard and it's built really well. The key to this thing is to keep the preamp volume turned to 10 and the master down. To get that bell clean you have to roll the volume knob on your guitar to 6. Sounds like a custom boutique amp should sound. Perfect for someone who wants to mess around with different tube configurations.

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Ridiculously Versatile Amp

Posted by Leftyaxman88 from OKC on Mar 7, 2007

Experience w/product: I have used it

Reviewer's Background: Active Musician

Reviewer's Play Style: Rock, Metal, Blues, Experimental

I just tried this baby out at Wild West Music in OKC. I was simply blown away. The one I tried had an EL34 and a 6L6 for power tubes and a set of 12ax7's. The tone was the most unique I've ever heard from any amp. Another thing that amazed me was how sensitive it was. I could set it to the highest gain setting possible and roll off the volume on my guitar down to make the signal just barely break up. I'm sold on this amp. I'm trading in my Marshall TSL 100 as soon as I can for this awesome amp. Huge props to THD!

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Great and very flexible amp

Posted by Al from Morris Plains, NJ on Apr 22, 2006

Experience w/product: I own it

Reviewer's Background: Active Musician

Reviewer's Play Style: Classic Rock, Blues, jazz

This amp can sound like most anything you want it to, depending on tubes and settings.. It can go from a very clean and warm sounding "american" amp, to a screaming "english" sounding amp. This is a single channel amp, but by using the volume control and knowing how to set up an amp properly it is quite flexible in a gigging situation.. I cover softer blues to led zepp with it in a gigging situation simply but working my guitar and the switchable overdrive on the amp..

This is a wonderful, very well built amp.

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THD Flexi-50 50W/20W Class AB Amplifier Head

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