mmolteratx « Only single channel vintage style amp I'll ever need »
Published on 03/17/11 at 20:44The Flexi 50 is a handbuilt tube amp made in Seattle, Washington by a mad scientist by the name of Andy Marshall.
The power output is switchable between 50w and 20w. Unlike many other amps that have this feature, this variation in output power is achieved by changing the HT supply voltage to the tubes rather than a pentode/triode switch. This keeps the tone and response of the pentode operation at a lower volume.
There is a switch on the back to select between 2/4 Ohm and 4/8/16 Ohm output impedances. Very useful for those who have oddball 2 Ohm cabs.
There's a switchable boost function with level and tone controls. It can be fairly transparent or cut/boost high end for different tones. Very useful for live situations as it can be controlled by a footswitch in addition to the front panel switch.
To keep things simple, there's only one input but there's a switch to change between high and low gain signal paths. It's not switchable via the footswitch unless you configure it to switch in/out with the boost.
The master volume is switchable by either a front panel switch or footswitch. Great for a lead boost if you're already running it fairly high.
The rest of the controls are volume (gain), treble, middle, bass and a cut knob. The tone stack is of the Baxandall type and as such allows for great flexibility and precision. I'm not sure where in the circuit the cut knob is but it acts much like a standard presence control.
There's also a line level series FX loop that works great for rack FX and a transformer isolated line out with a level control that is awesome for those who run dry/wet stereo rigs.
There are also external bias test points that make biasing a simple 30 second operation, a god send due to the ability to switch out power tubes as you wish.
The O'Netics transformers are also shielded for low noise.
UTILIZATION
Dialing in a good sound is extremely simple. Some sample settings are included in the manual for those who would like a good place to start.
The manual is great and explains limitations and valid tube substitutions. It also explains how to bias the amp with precision and consistency. If you ever lose it, a copy can be found on the THD website very easily and the tube substitutions are listed on the chassis.
SOUNDS
I use either a '56 RI Strat with Lollar Blackface pups or a Standard Strat with a BareKnuckle VHII in the bridge. Both sound killer.
I find that the mid knob likes to be run fairly high, ie past 2 o clock, the bass knob likes to be kept low when using distortion and higher when using cleans. The treble knob is similar, as is the cut knob. The boost tone can be set pretty much anywhere and sound great, it just depends on what you want out of the boost.
The touch sensitivity is outstanding. With the gain all the way up in high gain mode with the boost on, you can clean it up completely just by using your volume knob and the tone doesn't thin out or muddy up like many amps. The boost function does seem to add a bit of compression, though it's nothing too much.
With 6L6 or 6V6 power tubes, I can get a nice Blackface Fender type tone with some scooped mids and higher bass/treble/presence. They're not exact, particularly due to the Black Back speakers I use but they're close enough for live use and could be dialed in further for studio use.
With EL34 power tubes, classic Marshall and hot rodded Marshall tones come very easily. Mids turned up, bass set with moderation and treble/cut set to whatever I'm feeling that day, classic Led Zeppelin and AC/DC through Van Halen and Ratt tones come very easily. All with fantastic clean up ability.
Clarity and note separation are killer. Complex chords can be played with moderate gain settings if you've got articulate pickups.
OVERALL OPINION
The thing I like most about it is the build quality. The THD stuff is built by FAA certified assemblers and it shows. The very first day I had it, I managed to drop it down a flight of stairs. Other than a few minor scratches and a slightly bent corner of the steel shell, it worked flawlessly afterwards. The steel corner was very easy to bend back into place and looks just like new now.
The thing I like least about it is that the variety of tones are a bit difficult to access live. Switchable channels would be great.
The value for a studio musician is killer. This could easily replace 2 or 3 amps that the muso would no longer have to cart around, saving set up time. For those with no experience in that area, time is very valuable in a studio.
A gigging musician may not like the lack of on the fly versatility but to be honest, it doesn't make near as much difference in that situation. You could easily do a gig with varying cleans and heavy tones throughout with the Flexi, it just won't be your ideal clean or dirty tone.
The amp sounds consistently great and I wouldn't worry at all about it all of a sudden sounding bad right before an important gig.
I didn't really try any similar amps before this as I wasn't looking for this type of amp when I bought it. I do have experience with many similar amps though and I can say the Flexi easily hangs with the best of them.
After owning the Flexi for a few months, I'd easily buy it again at the price I got it at and probably even the new price, though I don't really buy music gear new. It's honestly the only single channel, vintage style amp a guy could ever need.
The power output is switchable between 50w and 20w. Unlike many other amps that have this feature, this variation in output power is achieved by changing the HT supply voltage to the tubes rather than a pentode/triode switch. This keeps the tone and response of the pentode operation at a lower volume.
There is a switch on the back to select between 2/4 Ohm and 4/8/16 Ohm output impedances. Very useful for those who have oddball 2 Ohm cabs.
There's a switchable boost function with level and tone controls. It can be fairly transparent or cut/boost high end for different tones. Very useful for live situations as it can be controlled by a footswitch in addition to the front panel switch.
To keep things simple, there's only one input but there's a switch to change between high and low gain signal paths. It's not switchable via the footswitch unless you configure it to switch in/out with the boost.
The master volume is switchable by either a front panel switch or footswitch. Great for a lead boost if you're already running it fairly high.
The rest of the controls are volume (gain), treble, middle, bass and a cut knob. The tone stack is of the Baxandall type and as such allows for great flexibility and precision. I'm not sure where in the circuit the cut knob is but it acts much like a standard presence control.
There's also a line level series FX loop that works great for rack FX and a transformer isolated line out with a level control that is awesome for those who run dry/wet stereo rigs.
There are also external bias test points that make biasing a simple 30 second operation, a god send due to the ability to switch out power tubes as you wish.
The O'Netics transformers are also shielded for low noise.
UTILIZATION
Dialing in a good sound is extremely simple. Some sample settings are included in the manual for those who would like a good place to start.
The manual is great and explains limitations and valid tube substitutions. It also explains how to bias the amp with precision and consistency. If you ever lose it, a copy can be found on the THD website very easily and the tube substitutions are listed on the chassis.
SOUNDS
I use either a '56 RI Strat with Lollar Blackface pups or a Standard Strat with a BareKnuckle VHII in the bridge. Both sound killer.
I find that the mid knob likes to be run fairly high, ie past 2 o clock, the bass knob likes to be kept low when using distortion and higher when using cleans. The treble knob is similar, as is the cut knob. The boost tone can be set pretty much anywhere and sound great, it just depends on what you want out of the boost.
The touch sensitivity is outstanding. With the gain all the way up in high gain mode with the boost on, you can clean it up completely just by using your volume knob and the tone doesn't thin out or muddy up like many amps. The boost function does seem to add a bit of compression, though it's nothing too much.
With 6L6 or 6V6 power tubes, I can get a nice Blackface Fender type tone with some scooped mids and higher bass/treble/presence. They're not exact, particularly due to the Black Back speakers I use but they're close enough for live use and could be dialed in further for studio use.
With EL34 power tubes, classic Marshall and hot rodded Marshall tones come very easily. Mids turned up, bass set with moderation and treble/cut set to whatever I'm feeling that day, classic Led Zeppelin and AC/DC through Van Halen and Ratt tones come very easily. All with fantastic clean up ability.
Clarity and note separation are killer. Complex chords can be played with moderate gain settings if you've got articulate pickups.
OVERALL OPINION
The thing I like most about it is the build quality. The THD stuff is built by FAA certified assemblers and it shows. The very first day I had it, I managed to drop it down a flight of stairs. Other than a few minor scratches and a slightly bent corner of the steel shell, it worked flawlessly afterwards. The steel corner was very easy to bend back into place and looks just like new now.
The thing I like least about it is that the variety of tones are a bit difficult to access live. Switchable channels would be great.
The value for a studio musician is killer. This could easily replace 2 or 3 amps that the muso would no longer have to cart around, saving set up time. For those with no experience in that area, time is very valuable in a studio.
A gigging musician may not like the lack of on the fly versatility but to be honest, it doesn't make near as much difference in that situation. You could easily do a gig with varying cleans and heavy tones throughout with the Flexi, it just won't be your ideal clean or dirty tone.
The amp sounds consistently great and I wouldn't worry at all about it all of a sudden sounding bad right before an important gig.
I didn't really try any similar amps before this as I wasn't looking for this type of amp when I bought it. I do have experience with many similar amps though and I can say the Flexi easily hangs with the best of them.
After owning the Flexi for a few months, I'd easily buy it again at the price I got it at and probably even the new price, though I don't really buy music gear new. It's honestly the only single channel, vintage style amp a guy could ever need.
