Tech 21 Hot-Rod Plexi

Plexi-type tones plus a little something extra...

by Phil O'Keefe

The late 60s-era Marshall Plexi is one of the most highly regarded and coveted amplifiers ever built, and the sound it makes, even in its stock form, is rockin' (and incredibly loud) to say the least. However, they're also big, heavy, and somewhat temperamental beasts that require fairly regular maintenance and re-tubing, and since they are vintage amps and no longer being manufactured, they can be rather hard to find, and the price can be substantial even if you do manage to locate one. Still, the sound is so in-demand that a good sounding alternative that can offer that tone at any volume level is definitely appealing, and that's what the Tech 21 Hot-Rod Plexi sets out to do. Let's take a closer look at the details.

What You Need To Know

• Tech 21 has incorporated portions of their SansAmp technology (but not the speaker emulation) into the Hot-Rod Plexi to give it tube amp style distortion characteristics. 

• The Hot-Rod Plexi has a cool purple sparkle finish with gold lettering and graphics. The contrast between the two colors makes it easy to see the labels, even when in a darkened studio or dimly-lit club. 

• The pedal measures 3.75" x 4.75" x 2" and weighs 12 ounces. 

• Input and output jacks are side mounted. The input impedance is 1megOhm, and the output impedance is 1kOhm.  

The controls are fairly straightforward. There are a total of five knobs:

• Level sets the overall output level of the Hot-Rod Plexi, and does so regardless of how much drive you have dialed up. This allows you to get very heavily distorted tones, even at lower volume levels. Good luck doing that with a real Plexi amp.  

• The Tone control is a low-pass filter that adjusts the high-cut from 10kHz near its maximum setting down to 1kHz at its lowest setting. When dimed (5 o'clock position) the EQ is flat, and you get that classic bright and brittle treble tone that Plexis are famous for. There's a small mark on the graphics to indicate this position. The Tone control works great for taming those abundant and edgy highs to your preferences, and it does it without getting too dark or muddy sounding. 

• Punch is a very powerful control and one of the coolest parts of this pedal in my opinion. Tech 21 says this control is designed to allow players the ability to dial up the balanced midrange response that is crucial for distorted tones, even when using the Hot-Rod Plexi with an amp with a midrange scoop. This is accomplished with a wide-band midrange (500Hz) EQ that gradually varies the bandwidth, depending on the amount of cut or boost applied. The result is quite effective, and you can get a ton of different tones and variations in overdrive amount, tone, and level just by adjusting this extremely useful control. 

• Drive adjusts the amount of gain and overdrive. There's a pretty broad range of drive on tap, and Tech 21 takes care to point out in the Hot-Rod Plexi's manual that this control is designed to interact with your guitar's volume control, and it does so quite well; by rolling off your volume the signal cleans up, and increasing your guitar's volume results in even more drive and grind. 

• The fifth control is labeled "Hot." This knob also has a second LED and footswitch associated with it, and can be turned on or off independently, but only if the main footswitch (and the rest of the pedal) is active. There are two main modes of operation - Stock and Hot. In Stock mode, the pedal is designed to give you the vibe of a unmodified '68 Plexi from input to speaker jack. The Hot circuit is designed to emulate a hot-rodded Plexi with an extra 12AX7 preamp tube installed in the preamp, and it can provide up to 28dB of additional preamp gain boost. This boost is in "front" of the rest of the pedal as opposed to being an output level boost, and when it's engaged it gives you even more grind than the "Stock" settings. 

• The switching uses Tech 21's great sounding buffered bypass and smooth, click-free custom footswitch actuators. There are two - one on the left for the main bypass (complete with a red LED that illuminates when the pedal's active) and the second one (on the right) is for switching Hot on and off. 

• For plugging in an optional AC adapter, a 2.1mm center-negative ("Boss-style") power jack is located on the left side of the pedal next to the 1/4" output jack. The pedal can also be powered by a 9V alkaline battery (not included). The battery access is easy - there's a tool-free access plate on the underside of the pedal that lets you install or replace the battery without having to take the pedal completely apart. The 1/4" input jack has a built-in switch that disconnects the battery from the circuit when no cable is inserted into the jack, so to conserve juice and make your battery last longer, make sure you unplug it whenever it's not being used. 

Limitations

• There is no SansAmp speaker emulation onboard, so it's not intended for direct recording or running straight into a PA by itself. However, it will work just great when placed before a SansAmp or Tech 21 Character series pedal (which also have SansAmp speaker emulation built-in). 

• The Hot knob is designed to increase gain and grind; it's not really a volume boost and won't significantly increase your volume for solos. However, it's great for going from overdriven to downright raging at the click of a (second, dedicated) footswitch. 

Conclusions

I really like the Tech 21 NYC Hot-Rod Plexi quite a bit. It's got loads of range and a sound that is very reminiscent of the vintage amp that it is based on. Its all-analog circuitry is surprisingly low-noise, which is rather unusual for a pedal that is capable of such high gain levels. The Punch and Tone controls are both wide-ranging and very effective, and allow you to use this pedal with a variety of different amps and still dial up a broad range of aggressive, Plexi amp-like tones. The Hot control can kick that up another order of magnitude at the click of a switch, and gives you that little something extra that a modded Plexi brings to the table. I can see this pedal becoming very popular with a wide range of players in a variety of genres, just as Plexi amps have, but ideally, it wants to rock - and rock hard. It can change the tone and character of a clean amp, send an amp on the edge of breakup into full distortion, or add even more grind to dirty amps. It's a cool sounding and versatile pedal that nails some very legendary tones. Well done Tech 21!

Resources

Musician's Friend Tech 21 Hot-Rod Plexi online catalog page ($215.00 MSRP, $179.00 "street")

Tech 21 NYC's Hot-Rod Plexi product web page

Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.