Swiss bassist Stephan Schertler began designing instrument transducers nearly 30 years ago, and his DYN and STAT pickups have grown to become industry standards for amplifying not only guitar and mandolin, but also bass, piano, violin, and other orchestral instruments. While Schertler may still be best known as a pickup company, for over a decade, the company has also built a solid reputation for its amplifiers. Many of Schertler’s amps, like the Unico and David, are specially tailored to optimize the performance of Schertler’s own pickups, but the new Jam series is leaner and meaner, stripped down for decidedly universal appeal. These amps also incorporate Class D power supplies and redesigned cabinets, resulting in Schertler’s most compact and affordable amps to date. I tested the baby of the Jam family, the 100-watt Jam 100 (150- and 400-watt models are also available).
Well Thought-Out Design
From its neatly stained and gracefully contoured wood finish to its beefy anodized heat sink and delicate dome tweeter, the Jam 100 looks like a cybernetic mashup of an acoustic guitar and a studio monitor. The compact 100-watt amp sportsfour channels, with a variety of input options. Two channels accommodate instruments or microphones with XLR and ¼-inch inputs, while a third is specialized for pickups with high- and low-impedance ¼-inch inputs. All three of these channels include three-band EQ and reverb. A fourth channel offers stereo RCA jacks suitable for connecting a CD player or iPod. Rounding out the features are an XLR DI out with ground lift and a pair of RCA recording outputs with level control. There is no dedicated tuner send or mute.
The delicate parts of the amp—the knobs and speakers—are well protected by the recessed control panel and tough-but-classy front grille. An integral stand mount lets you get the amp off the floor or lean it at an angle with an optional kickback stand. My only ergonomic complaint is that while the recessed side handles are elegant, the lack of a center handle makes the Jam tricky to carry with one hand.
Multiple Choice Inputs
I tested the Jam 100 with a Santa Cruz OM, a Collings D2, and a Taylor 412, equipped with a variety of magnetic and piezo pickups, passive and active. We guitarists throw a huge variety of signals at an amplifier, and the first step with any amp is determining which of its inputs is best matched to a particular pickup rig. I found the Jam’s three 1/4-inch “high-z” inputs were perfect for medium-output active systems like the Fishman Acoustic Matrix, Taylor Expression System, and L.R. Baggs M1 Active. I’d expect virtually any pickup/preamp that runs off one or two nine-volt batteries to work equally well.
If you’re using a passive pickup, things get trickier. The 1/4-inch inputs on channels one and two are 10 kilohms, while channel three’s “high-z” input is considerably higher at 47 kilohms. Unfortunately, this is still lower than ideal for passivepiezo pickups, which generally sound best connected to a minimum of 1 megohms. If your guitar has no internal preamp, youmightlike the sound of it plugged straight into the Schertler, but most likely, you’ll want an outboard preamp. My Pick-up the World UST sounded thin and weak plugged directly in to the Jam, but it sounded great into any of the inputs when I first buffered it with an L.R. Baggs Para DI preamp.
At the other end of the level spectrum, a particularly hot preamp can overdrive an amp’s input, and for this reason the Jam 100 wisely includes a padded low-impedance input. I tested the Jam with a Pendulum SPS-1, a veritable flame-thrower that easily distorts many amps and consoles, and it sounded crystal clear into the Jam 100’s “low-z” 1/4-inch input.
Other than the slightly complex input options, the Schertler Jam 100 is totally plug-and-play, and it sounds tremendous. With magnetic and piezo pickups alike, I found the compact 100-watter warm and flattering in the midrange and smooth, silky, and clear on top. It’s a great match for an acoustic guitar, especially due to its well-placed low-frequency roll-off that helps focus guitar tone, while remaining full, warm, and deep.
Beyond the Basics
The Jam 100’s three-band EQ provides excellent, broad tone shaping, with the Low control adding fullness or controlling runaway bass and the High control nicely boosting or ducking brightness without getting brash or muddy. The mid EQ is centered at 460 Hz, good for adding warmth or cutting howling feedback, but its frequency is fixed and there’s no notch filter. All the knobs on the amp turn smoothly and are continuous (no center detent).
Each of the three main channels has an FX knob that might more clearly be labeled “reverb,” since that is the only internal effect, and it’s not adjustable (other than the amount). But sometimes simple is best, and this digital hall simulation conjures a warm, natural, and spacious ambience. At times, I wished I could shorten the rather long, slightly-pulsing decay, but I found the reverb very pleasing in moderation, suitable for both guitar and vocals.
The Jam 100 has phantom power on its XLR inputs, and it’s especially nice that engaging phantom power generates only a faint pop in the speakers if you (for shame) toggle the switch with the volume cranked. With many acoustic amps, phantom power means low-voltage phantom—either 12 or 24 volts—but the Jam got my hopes up with its 48 V switch. Sadly, it turns out to actually be 33 volts, which works great with many popular mics, but isn’t enough juice for a Neumann KM 184 or a Pendulum endpin preamp.
Some amps skimp on their DIs, but not the Jam. Its balanced XLR output is clean and transparent, with flat frequency response and low noise and distortion. And special props go to the excellent ground lift. In my opinion, anything with a balanced output needs a ground lift for live use, but many acoustic amps and preamps fail here. With the Jam’s ground lifted, I had zero ground hum problems, even when I ran a DI to the snake at a venue notorious for funky stage power. Nice!
Impressed by the Jam 100’s sound, I decided to compare it with its larger sibling, the Schertler PUB280, as well as a Mackie SRM450 powered PA speaker, which are both more than twice the Jam 100’s weight and power. The bigger amps immediately delivered more muscle and thump even at moderate volume, projecting rock riffs and bluegrass flatpicking with more attitude and dynamics, but for solo fingerstyle and single-note jazz runs I preferred the slightly gentler, more spongy response of the Jam 100. And I particularly liked how gracefully the Jam maxed out its volume: instead of blatting or distorting, it compressed and rounded the tone pleasantly as it hit its volume ceiling.
The Jam 100 was not only an excellent match for the various acoustic guitars I tried it with, it also amplified my Collings mandolin (which is outfitted with a Pick-up the World pickup, run through a Para DI) with nice detail and fullness, and while it couldn’t fully capture the lowest half-octave of the upright bass I tried it with, the Schertler never got flabby, hanging in there on the low notes remarkably well given its size. It also reproduced vocals through a Shure SM-58 mic with pleasant warmth and clarity. For rehearsals and small gigs, an acoustic duo could easily get by using only the Jam.
The Schertler Jam 100 is an excellent choice for any acoustic performer seeking a compact amp for small to mid-size venues. It also works great as a monitor on a bigger stage with its DI sent to the house PA. You’ll need to couple the Jam with an external preamp/EQ if you require advanced features like sweepable midrange, phase switching, or tuner muting, and aggressive flatpickers might prefer one of the more powerful amps in the Jam line, but for purity of tone in this size/weight class, the Jam 100 is about as good as it gets.
SPECS: Four channels (two with 1/4-inch and XLR inputs, one with dual hi/low impedance 1/4-inch input, one stereo RCA aux input). EQ (three-band on channels one, two, and three; two bands on aux channel) and reverb on each channel. 33 volts phantom power. 100 watts, bi-amped. Six-inch speaker plus compression tweeter. Master DI output with ground lift. 10.6 x 11.4 x 14.2 inches, 24 lb. Wood or gray finish. Engineered in Switzerland. Made in Italy.
PRICE:$999 list/$799 street.
MAKER:Schertler USA: (800) 789-2216; schertler.com.