Hands-On Review:Ampeg J20 Jet Guitar Combo

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Vintage tube tone in an attractive, affordable package

By Mike Fitch
Musician’s Friend Staff Writer


As a guitar player who’s also a huge digital technology freak, I’ve  heard some impressive digital vintage amp models over the last several  years. But when it comes to tube amplifier tone, as the song said,  “ain’t nothing like the real thing.” Until recently, finding an  authentic tube amp meant tracking down a heavily-used vintage box or  paying top dollar for a large British-type combo that sounds great but  is too loud for most real-world venues.


The Ampeg J20 Jet Guitar Combo is for those who prefer the genuine article—a  point-to-point hand-wired, all-tube amplifier that brings back the power  and fun saturation that filled the airwaves in the glory days of  vintage rock and soul. And it delivers those tasty tones at a  comfortable volume that won’t send your audience running for the exits,  especially in the small-to-medium clubs in which you’ll find the average  working player gigging at most weekends.


Diamond Blue


The J20 Jet is a straightforward 20-watt, class AB combo amplifier with tremolo, a  single 12" speaker, plus an included footswitch for turning the tremolo  on and off. The Jet’s design evokes the 5E3 circuitry found in a range  of classic amplifiers manufactured some thirty to forty years ago, but  provides more headroom for a better, more coherent sound.


The J20 shares the characteristic blue-checked retro appearance found on the  rest of Ampeg’s Diamond Blue Amplifier Series, a look that originates  from the classic Ampeg amps of the ’60s. The J20 harkens back to an earlier age when the average guy could be his own  car mechanic, beats were played instead of “programmed,” and amps had  simple controls that didn’t take a computer engineer to understand.


If you remove the back panel from the J20,  you will discover something missing that’s usually ubiquitous in  amplifiers today—a circuit board. That’s because, rather than using  integrated circuits, the J-20’s “point-to-point” wiring is soldered by  hand in a labor-intensive process that’s usually found only in very  pricey boutique amplifiers.


Sound Impressions


First I plugged my dual-humbucker guitar into the normal input on the J20,  and turned the volume up about 1/4. The sound immediately hit me as  very tight and clean, with none of the annoying fraction-of-a-second  delay one sometimes hears in an amp. And the sucker is LOUD given its  relatively modest size and wattage. The in-your-face tone brought to  mind Booker T & the MGs, Steve Cropper, Muscle Shoals, Stax, Motown,  and other classic ’60s rock and soul guitar sounds. I found myself  inexorably drawn to playing the scratchy funk rhythms and rumbling rock  chords that seem to come so naturally to the J20.


When I turned it up halfway, the tube compression kicked in for a  pleasing vintage crunch, but the tone kept its integrity and didn’t  start to disintegrate as sometimes happens with inferior amps—a credit  to the quality of the 12" alnico speaker that pumps out the J20’s sound.


The other “bright” input gave the sound an edge that cut like a  freshly sharpened machete. Most players would generally opt for the  normal input, although jazzers who play large, hollowbody electrics  would doubtless find the bright input useful for getting a harder-edged  sound.


To hear how it handled a more high-gain distorted sound, I plugged in  my overdrive pedal. The tone retained its brightness and presence well,  even when I cranked the distortion to a level verging on anarchy.


The J20’s single onboard effect is tremolo, and it’s a nicely done modulation  accomplished without using the modern shortcut of photo resisters.  There’s a satisfying depth to the oscillation. Rate and depth controls  allow you to dial-in the variety of tremolo you desire, ranging from  Dick Dale-style surf to spaghetti western. Overall the effect gets high  marks and its inclusion is very much in keeping with the amp’s vibe and  performance.


Tubular tone


Three distinct types of tubes are built into the J20’s architecture, including three 12AX7 preamp tubes, two 6V6s operating in  fixed-bias mode, plus a 5AR4 rectifier tube. The power configuration  closely resembles that of the classic tube amplifiers of the ’60s and  ’70s. All this tube power creates more volume than the 20-watt specs  would lead you to expect—I seldom find myself turning the volume up  halfway, even while performing with my electric blues band, which gets  pretty loud.


An external speaker output jack gives you the option of running an  external cabinet, and those who want greater coverage for larger rooms  might want to take advantage of this option. Another strategy would be  to buy a pair of J20s and run both of them with an audio splitter.


Volume and tone control knobs of the classic “stove-top” design make  dialing in your desired sound and amount of edge a piece of cake.


Get amped up


If you’re looking for a small combo amp that delivers powerful,  clean, and authentic tube sound that’s dressed down in an attractively  retro package with undeniable stage presence, you’ll definitely want to  check out the Ampeg J20.  The sound is full, brilliant, and maintains its tonal integrity and  focus when you pump up the volume. The handmade construction techniques  give it the authority of a meticulously well-made object. Easily fitting  into the back seat of a compact car, and at 25 pounds presenting no  problem to haul around, the J20 should find itself a niche among club date guitarists. For the  vintage-tone loving rock, jazz, blues, funk, or soul player, the sound  alone should make owning the J20 a very attractive proposition.


Features & Specs

  • RMS Power Output:
  • 15W (Cathode bias) 20W (Fixed bias)
  • Class AB Speaker: 1 x 12" alnico
  • Preamp tubes: (3 x 12AX7)
  • Power Amp tubes: (2 x 6V6)
  • Rectifier Tube: (5AR4)
  • Controls: Volume, Tone
  • Effects: Bias-vary Tremolo
  • Footswitch: Tremolo On/Off
  • Speaker Output: 1/4" jack
  • 20W" x 17-1/2"H x 9-3/4"D
  • Weight: 25 lbs.