The Roland Revo 250 was the studio flagship of the Revo product line, and, like its smaller 30 and 150 siblings, was one of the company’s earliest attempts to create a spatial effect. These self-contained amp-plus-speakers units lack the subtlety of the Doppler and amplitude-modulation effects produced by a Leslie. They are also quite rare and can demand about $3,000 today. Note the classic early-Roland look of the control box.

Ben, what comes to mind when I say solid-state amps?
They are really cutting and have a kinda forward presence to the midrange—especially when blended with tube amps. Since tube amps have that kinda sag at a certain point, which sounds cool, solid-state is a nice compliment to that. If you start stacking too much of the same element in a mix, it gets lost, but if you double up parts with a slightly different sound, they become a nice foil for each other. I know we are talking guitar amps here, but for keyboard or synth amps, they are all pretty much solid-state these days. As far as voicings go, tube amps work with guitars, whereas synths sound more natural with solid-state.

Does a tube or a solid-state amp make you reach for a certain microphone over another?
I don’t think so. I’d probably just use the same mics—maybe use a slightly darker mic for the solid state amp. But generally, I’d just use the same mics and maybe add some EQ later in the mix.

There’s a solid-state amp that’s one of my favorites ever: the Roland Revo 250. Its Roland’s take on [an amplified] Leslie speaker. However, instead of an actual mechanical moving baffle/horn arrangement, it’s got a giant 18" woofer that’s down-firing. Then, for the horns, instead of rotating, it’s got six smaller speakers. I think they are 8" inch speakers, and they are arranged in batches of two in a semicircle. It then electronically pans across them. So, you get less of the phase shifted part of the Doppler effect, but the volume part of it is a little more dramatic. There’s also less whooshy mechanical noise. What it sounds like is more of a natural chorus. When you play it on the slow setting, in a room, it just fills up the environment. It sounds like the coolest chorus ever.

Let’s digress from the conversation to peer behind the Revo’s grille cloth. The Revo, which was debuted by Roland in 1975, came in 30, 125, and 250 designations. The 30 was the smallest—essentially a pair of bookshelf-sized speakers with a stereo amp and built-in chorus. The 250, favored by Ben, was the big daddy, with it’s 18" downward driver and six 8" cones, electrically fired in sets of two, to approximate the Leslie’s rotating horn setup. There’s reverb, too! It’s a tall cab, and formidable in weight, but not as much as a Leslie 145 rotating-speaker cabinet. The Revo has an accompanying foot controller reminiscent of the Roland AS-1 Sustainer or Roland/Boss CE-1 Chorus Ensemble. It’s called the Revo Control Box RC-1. The input has a Hi/Lo sensitivity switch, and there’s a piano or organ selector switch, plus four footswitches to control the cancel (bypass), slow, fast, and chorus functions.

And the sound? It’s room-filling, with nice headroom that especially shines in the slower chorale modes. The 30, 150, and 250 models each have a different power output, speaker complement, and other features. One thing that really shines is the ramp of its oscillator. From chorus to flutter, there’s a smooth ramp-in rate and an even more pronounced effect from full speed to slow or chorus.

“They are really cutting and have a kinda forward presence to the midrange—especially when blended with tube amps.” —Ben Vehorn

But Wait, There’s More
I thought of a few more amps that might be interesting to check out, including one that is on my repair bench as I write this article. It’s an absolute monster and had me looking on eBay for era-correct parts to not only refurbish it to its intended sonic glory, but to build up the preamp, for my own tinkering. It’s a Kustom 400B. Charles “Bud” Ross started building Kustom amps in the mid ’60s. They are known for their unique look and sound, with their tuck and roll Naugahyde covering. All the models I’ve seen are solid-state, with various ones sporting bright switches, boost options, tremolo, and/or reverb. The Kustom amp line stands tall in my mind as some of the best sounding solid-state amps.

In the case of the Kustom 400B, there’s 200 watts of clean and mean solid-state power when used in mono mode. And yeah, this amp model has selectable mono or stereo operation. It crosses over into the public address realm with its four channels, which can be mixed to one speaker output, or two preamps to one power amp section and two to the other. So it’s like a PA mixer that can sum the input signals to mono or let you mix two channels to one speaker output and two others to another speaker output. Dope!

The preamps offer simple tone shaping, and the strongest tone-shaping option is the inputs themselves. Each of the four channels has high and low instrument inputs. The high seems to be tailored for full-frequency amplification. Plug a line-level-out synth into this input and enjoy the extended range it has to offer.

This is a lot of amp. Originally designed for use as a PA head, the Kustom 400B also quickly fell into the hands of bassists and guitarists. Separate power amps are share by channels 1 and 2, and 3 and 4. If you like dirt, but don’t want to blow out Godzilla’s hearing, you’ll need some stompboxes. On the plus side, you can pick up a 400B for a couple hundred bucks.

The low input isn’t just a gain-reduction option. It also offers a better interface for hi-impedance instruments. In other words, guitars. The amplitude and tone shaping controls are the tried and true combo of volume, treble, and bass. And they’re responsive, offering a feeling of cut and boost in one control. There’s no global master volume on this amp, so the volume is, well, the volume. There is also a bright switch option per channel. In the middle of the faceplate is the mono/stereo switch, for telling the output finals to work together or separately. On the rear of the amp, there are just simple speaker outs.

How does it sound? It rips! This Kustom is a back-wall blower-outer that’s just frightfully loud, pummeling whatever cabinets are plugged into it. I was testing the stereo mode with a 2x12 cab with Celestion V30s plus a 15"-speaker Ampeg bass cab. The 2x12 was handling a majority of the output duties, and bringing in the Ampeg rounded out the low end to give it authority. Onstage, you might want to be on the side opposite of the bass player, since you’ll be getting that “your guitar has more bass than my bass amp” look. The timbre is sweet and the attack immediate, with a nice chewy feel when hit hard with pedals or just a heavy picking hand. I’d love to tell you I dimed it, but I didn’t for fear of hearing loss. It came across my repair bench because one side of its preamps just didn’t sound right. It had been worked on before, and some under-spec parts were used for the repair. It also needed new power filters. It was a dream to work on. Each section of the amp, preamps, and power amps were on their own PCB—in almost a modular design. That made it easy to navigate and isolate problems in each section, rather than wrangle with a bunch of duplicated circuits all on one PCB. Thanks, Bud Ross!

Our final solid-state amp you oughta get to know is the amiably named Kasino Little Joe. And it’s related to our Kustom. Bud Ross sold the Kustom brand to Baldwin in 1972, and Baldwin—best known for their pianos—continued to manufacture Kustom amps and introduced a new line called Kasino. These were similar to the Kustom line, but with different aesthetics. The tuck and roll look of the Kustoms was ditched for the safer and possibly more appealing look of standard Tolex. So if a player was searching for the Kustom sound, but didn’t want an amp that looked like the back seat of a Cadillac, a Kasino was the ticket. Nonetheless, the Kasino line had its charms, with broad pinstripe grille cloth and recessed dials.

The Little Joe also has its volume, boasting an output rating of 125 watts. It has Hi and Lo instrument inputs, and a drive control allows tailoring the gain structure of the preamp. The standard controls are there: volume, bass, mid, and treble. The treble control also has a bright setting. And there are onboard effects, starting with tremolo and reverb. The tremolo has speed and depth controls, while the reverb has an intensity control that can be pulled up to a “high” reverb setting. Then, to really shape the timbre of the reverberation, they included a tone knob. That’s cool!

At 125 watts, the Kasino Little Joe is bigger than its name implies. There’s also an abundance of onboard effects, including boost, fuzz, tremolo, reverb, and gain—all of which makes this amp about as ’70s cool as Starsky & Hutch. Also note the broad pinstriping on the cabinet’s grille cloth and unusual porting in the back panel. These amps are currently selling for $650 to $800, depending on their condition.

Lastly, the Little Joe offers a boost option, with its own control, to get just the right amount of preset boost for every situation. Plus, there’s a fuzz circuit in there with its own gain control, labeled “effect,” and a level control to govern the output. With all those sonic options, this amp is a pedal company’s nightmare! It’s got all the essentials in one box. The rear of the amp sports a single speaker out, which was designed to be paired with a matching 4x12 cabinet with a slotted rear panel for focused, yet room-filling, sound. There are four footswitch jacks for controlling the various onboard effects.

And the upshot on its sound? Let’s hear it from Karl Vorndran, part of the sales team at EarthQuaker Devices and the owner of the Kasino Little Joe that I investigated here. Karl: “The amp is loud, with lots of bass and mids. The built-in effects have a very ’70s sound, which pairs well with the raw sound of the solid-state head. It’s aggressive: perfect for thick, overdriven power chords and ripping fuzzed-out ’70s riffs.”

So those are our six contenders for transistor-amp glory. But, after contemplating my tubes verses solid-state biases, and getting a gander and earful of these transistorized beasts, here’s what I think: There are tube amps and there are solid-state amps. Why not use both and choose each model for its individual strengths? Let’s make transistors and tubes a uniter, instead of a divider!