I love the word “vintage”. If you were to believe all the hucksters on eBay, you’d think that vintage gear refers to any old piece of junk that was made some time in the past. A title like “Vintage POD 2.0” and “Vintage PRS SE” wouldn’t be too far of a stretch! When I think of vintage gear I think of high quality items that reference a special era or particular method of production. For me, it’s as much about image and feel as it is about tone. I think about pre-war acoustic guitars, 1950’s and 60’s Fender and Gibson guitars and amps, and maybe lawsuit era Japanese acoustic and electric guitars. Oh..and vacuum tubes…lots of them. These are all rarities for varying reasons including limited production, materials, technology, and manufacturing. Some of these items simply can’t be reproduced.

My other observation about vintage gear is that most of it is pretty junky. That amp was probably sitting under a porch for 20 years in the rain with someone using a pair of vice-grips to turn the knobs. That old guitar was probably locked in a grandmother’s attic with no saddle and three strings somehow still attached. The stuff that I really want, the good condition stuff, is already in a collection somewhere or too costly for the average person to even contemplate.

What I really want is for items of desirable quality to be re-manufactured. I like the idea of “new-vintage”. Where I get the quality, the vibe, and the feel … and maybe even the personality and “squirelliness” … of vintage gear without the crazy price tag and with a warranty!

The great thing is that I have seen a renaissance of sorts in the market. A recognition of the real meaning of vintage. Ampeg is one company returning to its roots with the Diamond Blue Series of guitar and bass amps. In this review, I’ll be taking a hard look at the good lookin and great sounding Jet 20 (J-20) guitar combo amp.

The Ampeg J-20 is a class AB, 20-watt, point-to-point all-tube amp featuring a foot-switchable, variable tremolo. It is covered by great looking 1960’s styled “blue diamond” tolex. Looking at the innards of the J-20 definitely reveals a throwback in electronics construction.



A couple of terms here we need to explain that apply to this amp. First is the term “tube”. Sometimes you’ll see the term “tube amp” – but that can mean almost anything. Some tube amps only have a single tube (usually a 12AX7) in the pre-amp section of otherwise solid-state construction. Some tube amps will use a tube in the pre-amp and a tube in the output stage (often a 6L6) to warm up the sound but the signal path is still largely transistor based. Read this – the J-20 has six (6) tubes and no circuit boards. The preamp section possess three 12AX7 tubes, and the output stage uses dual 6V6’s. A Sovtek 5AR4 tube rectifier completes the spectrum.

Another phrase that may be new to you is “point-to-point”. Even if an amp is truly “all tube” there are a number of ways to wire all this goodness together – point-to-point, stripboard (or tagboard), and PCB (printed circuit board). In point-to-point wiring each component connects to a jack, tube pin, or solder lug. Usually, all this is done by hand, and there are no pre-printed boards. This harkens back to the era when you could actually work on your own car and repairs were as simple as yanking out the broken part and putting in a new one.






J-20 Features at a Glance

• Vintage-style point-to-point wired tube guitar combo
• 20W power
• Fixed bias Class AB design
• 12" alnico speaker
• 3 - 12AX7 preamp tubes
• 2 - 6V6 power tubes
• 5AR4 tube rectifier
• Volume and Tone controls
• Tremolo circuit
• Tremolo On/Off footswitch
• Dual 1/4" outputs
• 20"W x 17.5"H x 9.75"D
• 25 lbs.

In this age of digital effects and “more-is-better” feature sets, the control panel on the J-20 is an exercise in simplicity. On the front panel there is are two input jacks – a “normal” jack and a “bright” jack that adds 20dB @ 10Khz of boost over the normal input. Two stove-style knobs control volume and tone. Two more stove-style knobs control the speed and intensity of the tremolo effect. Two switches control the master power and standby mode.

There are only three jacks on the back panel. One is used for the tremolo foot switch that is included with the amp. Two more outputs include an 8 ohm jack for the internal speaker and one for an external cabinet.

One thing to note is that this amp is a throwback to an age where the tube amp was the effect. There is not an effects loop or even a separate gain stage control.

Sound Test

I spent some time with the J-20 playing it “straight” and with outboard effects and in general was very pleased by the tone. I played a variety of guitars through this amp including a G&L Custom semi-hollow ASAT with Seymour Duncan humbuckers, a G&L Comanche, and threw in an Epiphone Dot Deluxe 335 just for grins.

My first impression was that this amp is really loud for a 20-watter– even for a tube amp. The J-20 is absolutely perfect for small to mid-size settings – or even larger arenas if you plan on micing up. The J-20 has a very vintage voice – more so than any amp I’ve heard in a while. I love the fact that volume knob actually works as it’s supposed to in that you can effectively dial in the tone you want. On volume settings 1-4 the amp is very clean, with warm tube overtones. Settings 4-7 gradually bring in a sweetly slippery overdrive reminiscent of Memphis Blues. Settings 7-10 begin to saturate the tubes for harmonically rich and authoritative classic rock distortion levels (think Angus) that still preserve the musical nature of the underlying chord.

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Gear Guy Tip: From the J-20 Manual: “If it’s been a while since the tubes were replaced and the sound from your amplifier lacks punch, fades in and out, loses highs or lows or produces unusual sounds, the power tubes probably need to be replaced. If your amplifier squeals, makes noise, loses gain, starts to hum, lacks “sensitivity”, or feels as if it is working against you, the preamplifier tubes may need to be replaced.”

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The tremolo effect can be clicked on and off via the included footswitch and modulated using the speed and intensity knobs. The speed knob changes the rate at which the effect vibrates and the intensity knob controls the depth of the tremolo (i.e., how audible the tremolo is relative to the overall signal). In terms of sound, the J-20 tremolo ranges from an airy shimmery effect to a wild “Dick Dale” tremolo reminiscent of surf rock. The only downside to the tremolo on the J-20 is that, when engaged, it tends to amplify noise that might be captured in the signal chain. Overall, however, outside of introducing a mild oscillation, I still think most hard core tremolo users will prefer an external effect, since the onboard tremolo also does not have a tap tempo.

Similar to other amps of this design – the J-20 exhibits a very slight hissing sound when engaged. This is not problematic for live use but may be challenging if you choose to mic the J-20 as a recording amp. Also, this amp has a tendency to amplify all sorts of unwanted RF signals coming through the signal chain. In my tests, I kept picking up noise from the local radio station. I unplugged everything and thankfully isolated the source as being outside of the amp – in particular the guitar cable. I went through three good quality cables before I found one with adequate shielding (a Pro Co Guardian). I also ran all my equipment through a Furman Power Factor Pro to remove any RF frequencies in the electrical system. I didn’t have one handy, but I would also recommend a good noise gate in front of the amp. The moral of this story is that you are only as good as your signal chain – so use good cables with good amps.

The J-20 handles external effects surprisingly well considering that all effects must be routed through the pre-amp stage. I actually preferred my tube based Damage Control Glass Nexus for tremolo, reverb, and delay since it offered more options and control. I’m not sure metal heads will be able to generate sufficient gain out of this amplifier to satisfy their wanton need to shred; however, I was able to dial in some great tones for alternative rock and punk that were decidedly thick and nasty.


Grade- A
Pro's – Vintage Vibe, All-Tube Point-to-Point Construction, Totally Satisfying Overdrive, Foot Switchable Tremolo
Con's- A bit noisy – make sure you have good external components and cables
Street Price $799


Conclusion

The Ampeg J-20 happily satisfies my urge for vintage sound. When you take this blue diamond patterned beauty out of the box, you immediately get the feeling that you scored one of those holy grails of guitardom. A long lost piece of electronic antiquity that was somehow tucked safely in your Grandpa's garage just waiting to be uncovered…that just so happens to be in pristine condition.

Tonally the J-20 truly shines with the warmth and grit you want from a great tube amplifier. The amp is loud, but you can still saturate this amp at volumes that won’t split your ears or bust windows. Like all great vintage amps – there aren’t lots of knobs and effects to play with outside of the onboard tremolo. This amp was built for players who understand and desire the unique advantages of hand wired electronics.

I loved the J-20 for its retro vibe and great tone. For this reason, I’m giving the J-20 the last GuitarGearHeads “Rig Ready” Award for 2007! Congratulations to Ampeg for another great product!




Dan Halberg

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†G&L is the Official Guitar of GuitarGearHeads.com for 2007.