Tropical Fish M3 tremolo effects unit & preamplifier

SPECIFICATIONS

• All-tube preamp with buffered, line-level output suitable for connecting to mixers, interfaces, and external amplifiers

• Two 12AU7s (which can be swapped for other tubes in the 12A_7 family for variations in gain and tone) and one 12AX7

• Tube tremolo with depth and speed controls, as well as a speed switch

• Powered RCA input for Wurlitzer and passive 1/4” input for guitar/instrument-level signals; alternatively, choose two passive 1/4” inputs

• Includes Wurlitzer input cable and phone or email support on how to connect the M3 to your keyboard

• Dimensions: 15” wide, 8” high, 8” deep

• Weight: 10.5lbs

• Voltage: 120V (available in export voltages: 200, 220, 230, 240V. Please inquire via the form below to indicate your choice. You can purchase the product on this page, and we will wire your amp as requested)

WHY USE A PREAMP?

The Tropical Fish M3 preamp was developed from our desire to record Wurlitzer electronic pianos while fully bypassing the onboard electronics. We wanted our design to accomplish several things:

• Clean voltage to power the pickup. A Wurlitzer pickup works more like a condenser microphone than a guitar pickup. To create a signal, it needs high voltage (between 80V and 120V—different models vary in how much voltage they send to the reed bar).

• A buffered output to send signal to any amp or mixer. We wanted an output signal that would work with any external device we might want to use for processing our Wurlitzer signal. In most cases, we wanted to send the Wurlitzer straight to our recording interface, but—for the most tonal possibilities—we also wanted the option to use one of our tube amplifiers if the project called for it.

• Clean gain. Sending the Wurlitzer signal to an interface would require a preamp—so we decided to include a gain stage in the design, in order to make the preamp an all-in-one solution. Because the design already required high voltage to power the reed bar, we opted for a tube-powered gain stage, rather than a solid state design. On the other hand, if we were connecting the preamp to a guitar amplifier, we wouldn’t need very much gain at all. So, we biased our gain stage to accept any tube in the 12A_7 family. A 12AU7 is perfect for both guitar amps and interfaces, but more gain can be achieved by swapping the 12AU7 for a 12AT7 or 12AY7.

• Onboard tremolo. Tremolo is part of the Wurlitzer sound, so onboard tremolo was an important feature for us!

The result was the Wurlitzer M1 and M2 preamps, which were designed to replace the internal amplifier of a Wurlitzer 120, 700, 720 or 140-series keyboard. But, when we recorded, we often used the M2 with our Wurlitzer 200A. Not only did the M2 sound great, but keeping the amplifier external solved a lot of shielding and noise issues that result from the proximity of the onboard 200A amplifier to the reed bar. So, because the preamp was so useful to us, we started designing a fully external version, and the M3 was born.

more gain, more tone, and more tremolo

Since the M3 amplifier is external, we no longer needed to work within the size constraints of a Wurlitzer 120/140 cabinet. For the M3, we added extra features that make the amplifier even more useful and versatile in the studio:

• Passive input(s) for guitar, Rhodes, combo organs & more. The passive input is fully isolated from the powered Wurlitzer input, so the M3 can also be used as a preamp for guitars, Rhodes—anything with an instrument-level signal output. Or, we can optionally build the M3 with two passive inputs, and no powered Wurlitzer input at all. This makes the M3 an all-tube, all-analog effects unit that provides both tremolo and clean gain boost.

• More options for gain. An additional triode stage adds more clean gain for recording with mixers and interfaces, without excessively overdriving a guitar amplifier. Because the M3 has gain stages across two tubes, it is possible to experiment with different tube combinations for more tonal possibilities.

• More options for tremolo speed. In addition to a tremolo speed knob, we added a switch so that the user can instantly toggle between fast and slow tremolo speeds.

Fully handmade with the best components available

Handmade, solid wood cabinet. The cabinet is handmade by Tropical Fish from solid 5/8” mahogany. Because we are making this batch of amplifiers to order, type of wood can be customized on request.

Point-to-point, hand-wired electronics. We learned point-to-point assembly from 10 years of rebuilding amplifiers in narrow 1950s tube amp chassis that can’t physically fit PCBs or turret boards. Although it is time-consuming, point-to-point assembly allows for maximum flexibility of layout, so that the signal path can be made as short and direct as possible. A short, direct signal path is the best way to maintain the original tonal character of the signal source while minimizing the noise floor. Much of the assembly time is spent mounting components precisely, with just the right amount of length on leads and wires. Leads that are too long or short can introduce noise into a circuit, or prevent the component from mounting securely. If we cut a wire too short, we toss it in the scrap pile and do it again. The result is consistent, high-quality construction from amplifier to amplifier.

We use the best passive components, no matter the cost. We have brought the material costs of the amplifier down as much as possible by buying parts in quantity. We have not brought costs down by skimping on the quality of the electronic components inside. We spend hours reading datasheets to find components with the lowest noise and highest performance.

• All resistors in the audio circuit are low-noise, audio-quality Vishay metal film resistors. Power supply resistors are high-quality wirewound.

• Electrolytic capacitors are chosen for low ESR.

• All coupling capacitors are polypropylene. For the output coupling capacitor, we use a 10uf Solen polypropylene ($5.79) instead of an equivalent electrolytic capacitor ($0.25).

• The amp’s faceplate is professionally screenprinted and powdercoated by local artisans in Mount Vernon and Port Chester, NY.

TREMOLO WITHOUT COMPROMISe

What is tremolo? Optocoupler tremolo—the type of tremolo used in the M3—affects the audio signal indirectly. Here’s how it works: an oscillator circuit creates a signal (in our case, a sine wave) that turns a light on and off. (In old amps, it’s neon; we’re using an LED.) The blinking LED changes the resistance of a light-dependent resistor (LDR). The LDR is the only tremolo component in the audio circuit, and its changing resistance (in time with the blinking of the LED) sends part of the audio signal to ground—kind of like if you were to turn the volume knob from 0 to 10 really fast, over and over again.

Our all-tube tremolo offers plenty of depth and a wide range of speeds. Our inspiration is the original Wurlitzer tremolo, which—for us—is a major factor in the iconic Wurlitzer sound. Wurlitzer used a lot of different tremolo circuits through the years, and all of them offered just one speed (fast). We wanted to achieve that trademark fast Wurlitzer speed, while also giving the option for slower speeds. In addition to a speed knob, we added a switch that selects between fast and slow tremolo. If desired, the user can use the switch to instantaneously and dramatically speed up and slow down the tremolo.

If you want classic tremolo, an onboard amp effect is the cleanest way to achieve it. There are a lot of very cool tremolo pedals out there, and we love using them! But unless you’re looking for the sound of a specific tremolo pedal, the best way to get classic tremolo is through an amplifier that you love using. Because the tremolo oscillator is completely separate from the audio circuit, tremolo is one of the least invasive amp effects there is. It doesn’t color your signal any more than a volume control would. But, once you add a pedal to the signal chain, you’re sending your entire signal through that pedal—and whatever components your signal passes through is going to affect the sound. What’s inside the pedal obviously depends on what kind of pedal it is, but most pedals (other than the very nice boutique ones) are designed less for signal fidelity than to achieve a certain market-tested price point. (They’re going to use the $0.25 capacitor instead of the $5.79 every day of the week.)

For effects like chorus or distortion, you have to send your signal through the chorus/distortion circuit in order to achieve the effect. So, in addition to adding the effect, the components that create that effect are changing your signal in subtle (and sometimes not-so-subtle) ways. That’s the tradeoff you have to make to achieve that effect, and it’s part of the effect’s overall character. Optocoupler tremolo isn’t like that—the effect itself is created through a circuit that is isolated from the signal path. That makes it one of the most transparent effects there is—unless, of course, you’re sending it through the mysterious innards of a tremolo pedal. In our opinion, a high-quality, all-tube circuit and an LDR is the best way to achieve tremolo.