If Yoda were a combo, he’d be the Koch ST20-CBy Darius Van Rhuehl
Musician’s Friend Staff Writer
I have to admit at first glance I thought the Koch ST20-C was probably just another practice amp. I couldn’t have been more wrong. As Yoda says, “Size matters not. Look at me. Judge me by my size do you? Hmm? And well you should not, for my ally is the ST20-C, and a powerful ally it is.” Okay, I added the bit about the Koch, but that doesn’t make the quote any less true—for the force is truly strong with this one, hmm, yes! And soon, there will be another, the more powerful 40W Studiotone XL. But don’t get me wrong, the ST20-C can push some serious air.
Do or do not, there is no try . . .Achieving the goal of building a high-quality, channel-switching amp that offers serious bang-for-the-buck and great sound, Koch has packed a massive amount of technology and functionality into the diminutive ST20-C. From the inside out, the ST20-C embodies quality construction from the solid birch cabinet to its Class A circuitry and custom-designed 12" speaker. Even the control knobs reflect the same quality inside and out. They’re nice to look at, smooth and solid to the touch, and feature 10 wipers per shaft that provide an evenly graded adjustment throughout their entire range—just what you’d expect from audiophile studio gear. Controls include two volume; gain; bass, mid, and treble EQ; and reverb (a short tank spring ’verb by Ruby). There are also two tone-shaping switches. One toggles the center frequency of the midrange control between 800Hz and 1.2kHz, depending on whether you’re going for midrange thump or extra presence. The other is a three-position bright switch that either cuts or boosts the highs. The middle position is neutral.
Bringing up the rearThe rear panel is where things really get interesting. Aside from the lit power and standby switches on the front panel, which eliminate guesswork on a dark stage, you’ll find a serial effects loop; mic placement and cabinet modeling switches; two line outputs, one unfiltered and one for connecting to the clean channel of another amp for a true stereo sound; headphone jack; and speaker outputs at 4, 8, and 16 ohms that allow you to use any combination of speakers. There’s also a speaker on/off switch, which is of particular interest. In the off position, the output is loaded with a 25W dummy load that lets you play at full volume without making a sound while allowing you to use the outputs for silent practice or recording. Speaking of recording, there’s also a direct recording output whose signal is derived from the speaker, which gives you tube saturation along with reverb and looped effects to disc. If all that weren’t enough, a special filter is applied to the output signal that simulates the recording characteristics of a miked amp.
“This is Red 5—I’m going in . . .”My first real-world test of the ST20-C was with my band. In rehearsal, it easily held its own against larger amps and drums, and didn’t need to be cranked to respond the way an amp should. Taking it to gigs was another revelation. Not only did it get even better at higher levels, it cut through the mix without stepping all over it—and was easy to put through the PA. In fact, the FOH engineer expressed his newly found love for this amp.
In my studio I tested both stereo line out and record out. Using the low-level line out, I was able to create a very nice stereo effect using a different brand combo amp of the same size. All you have to do is make sure the amps are in phase and the levels of the two amps are the same. Simply adjust the volume until you hear the center image. The other amp had to be cranked up quite a bit more to keep up with the Koch. If the amps are out of phase, you hear the sound from left and right. Just for fun, I inserted a rotary speaker effects pedal between the two amps.
Running the record output to the line in of my A Designs Audio Pacifica preamp yielded stellar results. Though I believe as multi-platinum hard rock/metal producer Michael Wagener does, “No room, no boom,” if I were feeling lazy, I could use the direct out of the ST20-C and never look back.
Another feature that I consider equally important as the circuits and sound is the people behind the gear—and Koch stands behind their amps with excellent service. When tube-replacement time comes, an auto-biasing circuit lets you replace its EL84 tubes yourself—no service calls.
“I have you now . . .”Having recently “survived” one of Michael Wagener’s production workshops, in which I learned how to record big-sounding guitars, I was wondering how I could come up with the bucks to duplicate even a small part of his setup. With the Koch, not only can you make a record, you can make several records, each with a distinctive tone. For me, the nice part is that I can use the Koch to define my sound and create my niche, rather than follow in the tonal footsteps of my illustrious teacher. Though it can give you the rich-in-harmonics VOX AC-style midrange with a side order of Marshall and Mesa on the overdrive channels, the Studiotone isn’t your typical rehash of vintage tone. It can boldly go where the aforementioned amps have never gone before. For me, that’s the beauty of this amp; I want to break new sonic ground, and I hope, so would all up-and-coming guitarists (both young, and 30-and-holding) and seasoned pros alike.
The ST20-C’s range of tonal options will cover any style of music with sound quality that makes it impossible to put your guitar down. From the moment I plugged into this amp, I knew I’d have to keep it—and made arrangements to buy my demo unit. I think that tells the whole story.