The Rocket A20R Recording Amp by ADA Electronics

PLEASE NOTE: This article has been archived. It first appeared on in June 1998, contributed by then Guitar and Amplifier Editor Daniel Hines. We will not be making any updates to the article. Please visit the home page for our latest content. Thank you!

Welcome to the ProRec guitar gear review. This is my first column for ProRec so I encourage plenty of feedback in case I’m not answering all relevant questions about a product. In any event, this column will focus on guitar equipment and real world advice on how it records and performs live. Over the next few weeks and months I’ll be reviewing an eclectic array of products such as the Godin LGX-SA synth access guitar, the Hamer Special, amps by Fender, Mesa and Trace Elliot, pedals by Prescription Electronics, and anything else that walks in the door. Thanks for reading and enjoy.

Some preliminary information on how the product has been reviewed… The ADA Rocket A20R has been played for almost 100 hours in a number of performance situations – recording, live performance and rehearsal. The guitars used to test the amp were a Hamer Special with P90 pickups, an Ovation UKII solid body electric with Bill Lawrence blade humbuckers, a Warmoth Strat with single coils, a Carvin 127 with dual humbuckers, an Epiphone Sorrento with P90’s and an Epiphone Sheraton with dual humbuckers. The amp was purchased for a little over $400, real world money. The manufacturer didn’t give the amp and has had no input in the writing of this article.

The ADA Rocket A20R

The Rocket was reissued by ADA in response to the vintage craze that has dominated amplifier design for the last four or five years. While ADA is not a particularly well known amp designer, and certainly not highly regarded by vintage enthusiasts, they really got it right the first time with the Rocket. However, like a lot of vintage inspired amps on the market right now, the Rocket is aimed squarely at the recording buff and isn’t really intended as a live performance machine.

The amp owes its looks and design to a pair of prototype amps discovered in a garage in Southern California. The amps were dated to 1949 based on a run number of the output transformer. With a switch hand-labeled “gain boost” the amp was clearly ahead of its time. The old prototypes were taken to ADA Electronics where they were cleaned and essentially reconstructed with new parts.

This amp is beautiful and owes a great deal of its aesthetic qualities to boutique amp designers such as Matchless. Covered in burgundy vinyl with cream piping, brown basket weave grill and a handsome leather handle, this amp is an eye catcher. Housed in a large cabinet with a single 12″ Eminence speaker, the amp’s controls are displayed on top like an old Vox.

The control layout is clean and simple: volume, treble, midrange, bass and reverb pots, as well as switches for bright, gain boost and “power amp thrust.” The amp has a simple on/off switch with a ruby jewel light and has an external speaker output jack. There is no standby switch.

The amps innards are equally simplistic. Accessing the chassis is easy with the removal of six screws. Once inside you find a single PC board layout featuring a single Sovtek EL34G power tube running in Pure Class A. The amp has three preamp tubes, one Phillips 12AT7 and two no-name 12AX7’s. All tubes are horizontally mounted. The amp has a small tank reverb and has a nice long power cord. The long power cord was particularly appreciated.

Plugging in you understand what a “recording” amp is supposed to sound like. The tone controls are extremely powerful and functional. The pots are effective through their entire range, allowing subtle variations in tone. They are interactive and allow for a lot of fine tuning. This amp, just using the tone controls, can go from Mississippi mud to shards of glass. However, regardless of the specific tone settings, this amp just sounds great.

Complimenting the powerful tone controls are the reverb and volume knobs, as well as the previously mentioned switches. The reverb sounds great. Easily one of the best reverbs around, especially considering the price range of this amp. It’s not a vintage Fender reverb unit, and a surf guitar enthusiast would always ask for more, but it’s incredibly useable. And that’s key for a recording amp. Why have it if you won’t use it in the studio? It’s full, rich and never “boingy.”

The volume control is really another tone control. At low to moderate settings this amp retains a clean, articulate sound. Every note has great definition and you can really hear the amp breath. Turning up the volume adds a Vox edginess that can get pretty zingy, but is easily tameable with the powerful tone controls. Very cool. Turning the volume knob further doesn’t increase the apparent loudness, but pushes the single EL34 harder for true power amp saturation. It’s great to get true “brown sound” at reasonable studio volumes.

Now for those switches. The bright switch adds a treble sheen to your notes, noticeable on even the warmest of humbucking guitars. Not piercing, but bell-like. The gain boost adds a little edge, but not true distortion like a modern voiced amp. It’s not much, but noticeable when you really lay into the strings. Finally, the “power amp thrust” switch adds a little bit of gritty boost. None of the switches dramatically affects the sound, but they all add unique tonal flavors, alone or in conjunction with each other. I found myself frequently flipping them all on, then riding the tone controls to tame any ice-picky tones.

The real sonic mojo of this amp doesn’t come from its powerful controls alone, but rather from the way they compliment the Rocket’s excellent choice of speaker and large cabinet. Unlike most low wattage amps, the Rocket comes in a full size combo cabinet. It’s deep and resonant, allowing notes to develop in front of the amp. The Eminence speaker sounds full and articulate. Like all great amps, it’s the way all elements come together that determines great tone. In this case, an EL34 running in Class A, powerful tone controls, an excellent speaker and a large cabinet all intersect for great, versatile, studio quality tone.

So how does this translate into the real world? Well, I’ll begin with my recording experiences. This amp was purchased last September for the sole purpose of recording. The particular project I was working on was a psychedelic, pop-rock album. The songs on the project, which took fifteen months to record, ranged from pure Smithereens power pop to Beatlesque Brit-pop to funky pop reminiscent of Prince’s glory days. In effect, every possible guitar tone imaginable was required on this album.

We had already been recording for 8 months when I bought the Rocket. Most of the sixteen tracks had been started, but none were finished. The album project was really taking too long and the band had been signed based on early demos from the album. The record label was really wanting the album finished. From September to February we used the Rocket almost exclusively to finish the album. We had already recorded hundreds of tracks of guitars with other amplifiers, but the Rocket was used to finish off small parts on already existing songs and to start entirely new tracks from scratch. Needless to say, the amp was versatile enough to add atmospheric touches or to lay down basic, crunchy rhythm tracks.

We were recording digitally using Cakewalk Pro Audio recording software, so we mixed on the fly. When we thought a song needed a small addition, we simply threw a microphone in front of the Rocket, which was kept in the control room, and recorded a part. Using primarily an AKG D1000 and an Audio Technica 4050 (two unusual guitar mics) we got stellar tones. The engineer on the project continued to marvel at the powerful tone controls. Most importantly, this amp just seemed to get lots of sound on “tape.”

I was particularly impressed with the way the amp let the natural voice of the guitar come through. The Hamer’s P90’s really sounded like P90’s… lots of squawk. The single coils and humbuckers responded well with this amp also. On this particular project we used a fair amount of stomp boxes and the Rocket really conveyed the particular sonic stamp of each unit. We used a Prescription Electronics Experience Pedal, Rat distortion, Ibanez TS-9 reissues, a MXR Phase 90 and Micro Amp, a Vox Distortion Booster, Morley wah and a Boss digital delay. The Rocket and its full range tone really made the pedals useful. Atmospheric parts with unique tones really seemed to jump out of the mix.

As I said before, this amp is aimed at the recording buff and isn’t really for live performance (it just looks too nice to spill beer on it!!!). However, it has seen a fair share of rehearsal and live performance. In terms of live performance, the amp still sounded great in a club. It’s voice remained clear and well defined, and the tone controls really helped fine tune the stage sound. The amp was used by a player who is primarily a rhythm guitarist. People in the crowd continually commented that the rhythm parts were particularly clear.

In one particular rehearsal I used the Rocket next to another guitarist who was playing a 100 watt Fender head through a Kustom cabinet with a 15″ speaker. At reasonable rehearsal volume levels the Rocket really held its own, cutting through nicely. Everyone was suitable impressed.

In summary, this is a great amplifier. It sounds great with any guitar and responds well with all sorts of stompboxes. It’s versatile in the studio for a number of reasons: the tone controls and switches can really fine tune the sound, the speaker and large cabinet help it sound bigger and fuller, the low wattage allows the player to attain true power amp saturation at reasonable levels, and lastly because it makes you want to play. This amp really has some mojo. It should work great for any studio, especially in studios that cater to a diverse clientele with innumerable sonic requests. And, it doesn’t hurt that it can double as a nice club or rehearsal amp.

Check in next time for another low wattage review . . . a shootout between Trace Elliot’s Velocette and Fender’s Pro Junior.