Although digital signal processing has improved in recent years, compression remains one area in which it falls short especially emulated tube compression.

Although digital signal processing has improved in recent years, compression remains one area in which it falls short — especially emulated tube compression. Not surprisingly, even the best plug-ins can't replicate the sound of true analog tube compression. But not every personal-studio owner can afford the typical outboard tube compressor.

Fortunately, there's an affordable alternative: the HHB Radius 3 Fat Man tube compressor. A fixed-stereo unit, the Fat Man can also function as a mono compressor and a tube DI box. The unit provides 15 presets, making it especially attractive for novice users. A manual setting is also provided.


As the name suggests, the Fat Man is unusual in size and shape: three rackspaces tall and a half rackspace wide with a top panel that slopes downward from front to rear. Indeed, you may wonder where to put the Fat Man in your studio. Racking the unit in HHB's optional rack panel ($79) is one solution — that is, if you have three rackspaces to spare. (The rack panel holds one Fat Man, centered or to one side, or two.) Otherwise, the unit's four rubber feet let it sit on a desk or table without marring the surface.

The Fat Man's purple front panel provides five continuously variable knobs for Input Gain, Output Gain, Gain Make-Up, Threshold, and Ratio. The Input and Output knobs have center detents at zero gain. A larger, stepped knob selects from 15 presets — Vocal 1, Vocal 2, Vocal 3, Keyboards, Bass 1, Bass 2, Ac. Guitar, Electric Guitar 1, Electric Guitar 2, Snare, Kick, Kit, Mix 1, Mix 2, and Mix 3 — and a manual setting.

Centered above the knobs is a nice VU meter. Beneath the knobs are five push-button switches: Compressor On (or bypass when not engaged), Meter (switchable between output level and gain reduction), Knee (for selecting hard or soft knee), and Attack and Release (both of which provide slow and fast settings). A rocker switch on the lower right turns on the power, and two LEDs on either side of the VU meter indicate whether the power is on and the compressor is engaged. On the lower left side of the faceplate are two instrument-input jacks (unbalanced) labeled Left/Mono and Right.

The Fat Man's rear panel provides balanced/unbalanced ¼-inch inputs and outputs (see Fig. 1). A switch for choosing either +4 dBu or -10 dBu operating levels is between the input and output jacks.

The Fat Man's sloping, ventilated top panel provides a view of the unit's single tube, a Russian-made 12AX7WA. An additional panel beneath the top one prevents dust from falling onto the electronics. Removing the top panel reveals a neatly laid-out printed circuit board with accessible fuses and adjustable pots for meter calibration and tube bias. Instead of using a voltage-controlled amplifier (VCA), the Fat Man has a transconductance amplifier — the same kind used in HHB's more expensive line of products.


I worked with the Fat Man's presets first, beginning with Ac. Guitar. I miked an acoustic guitar with a tube mic and solid-state preamp and patched the signal into the Fat Man. The preset worked well. It increased the low mids and sustain; emphasized the strumming; and even controlled a few loud, errant strums without noticeable compression. The highs were also fairly well retained, and overall, the processed track provided more oomph. I also received good results with the two electric-guitar presets.

I patched the Fat Man through console inserts to test it on electric bass. On miked and DI tracks, the unit did what I desired, adding sustain, controlling the dynamic range, and evening out the performance. Both bass presets worked well. I adjusted the input and output gain to get the desired amount of gain reduction and was also able to add some nice tube sound. I really liked the quality of distortion that the tube stage provided.


Certain sounds (drums, for example) have very fast attacks, and I have never found an affordable compressor that effectively controls them. The same goes for certain vocals, especially in extreme styles, such as punk, that may involve screaming.

The Fat Man's presets for kick and snare drum worked fine — quite well, in fact, considering the unit's price — and sounded transparent to as high as 3 dB of gain reduction; beyond that, the compression started getting noticeable (which is not necessarily a bad thing). Yet I couldn't get the sound I wanted from those sources using the Fat Man's presets. The kick sounded beefier, but it had too much sustain. The snare sound wasn't to my liking, either — I'd prefer a good ol' dbx 160 compressing snare drum.

I tried manual mode, too, but still couldn't find optimal settings for those difficult sounds. Sure, I had warm, usable sounds; but I'd still have to spend a lot more money ($2,000 to $3,000 per channel) to get a compressor that can showcase the nuances of, say, a long, quiet snare drumroll, or one that perfectly controls every aspect of a vocal track.


Most compressors — especially budget ones — chop a little off the top end of signals, which is especially noticeable when processing cymbal tracks. Indeed, it is a commonly accepted practice for users to insert compressors pre-EQ so that they can boost the high end after the dynamic control takes place. Unlike many of the other compressors in its price range, the Fat Man does a good job of retaining high frequencies.

One of my favorite mix tricks is to compress the room mics or stereo drum overheads before sending them through a reverb device. That helps tighten up the sound, which limits peaks that can jolt or jangle a spring or plate reverb. The Fat Man did a fine job in that application (in Manual mode and with Mix 1, Mix 2, and Kit presets) and left overhead and room sounds fairly unscathed. I heard a slight high-end loss, but the cymbals maintained sufficient crispness.

I also tried the application in a live situation, patching the Fat Man into the drum-overhead inserts. During sound check I switched the compressor in and out and was pleased by how it controlled the drums' dynamic range yet retained considerable brightness.


I also tested the Fat Man as a stereo-program compressor. One source was a DAT of a live rock band recorded without compression from the console. I set the unit to Manual mode, soft knee, and slow attack and release times, and then adjusted the threshold and ratio for approximately 6 dB of gain reduction. The VU meter's needle danced with the snare hits, but the Fat Man's action was smooth and didn't punch holes in the rest of the mix. Although I could hear the compression, the Fat Man produced the desired effect: a nice addition to the tone; a thicker, more even sound; and overall, a more listenable tape.

I dialed in a similar amount of gain reduction on an acoustic-band mix with equally good results. The acoustic instruments (mandolin, guitar, upright bass, and banjo) sounded punchy, cohesive, and dynamically controlled while retaining a live quality. Feedback and pops were also well tamed.

On more critical sources — final mixes of studio recordings, for example — I liked the overall sound of the Fat Man, but the loss of high-frequency content was more problematic. Although the Fat Man is more than adequate as a stereo-program compressor in live situations (including broadcast) and even for fattening up personal-studio demo mixes, I wouldn't recommend it for mastering critical record projects.


I often mix sound for bands on the air live at radio station KDVS in Davis, California. The Fat Man excelled in that environment. Strapped across the stereo output of the console, it provided tighter, warmer-sounding mixes than what I was accustomed to, and the sound I heard in the control room was more similar to the broadcast sound than usual. In addition, the compressor normally used for broadcast didn't have to work as hard. (Radio stations compress their output before transmission in order to broadcast more efficiently; at KDVS, the house compressor is permanently installed as the last stage before the transmitter.)

Though I mostly worked in manual mode when using the Fat Man at the station, the presets came in handy one night when I had to mix and record — to DAT and ADAT simultaneously — a broadcast of the band Lazybones. I had little setup time and a lot to attend to, so the presets saved the day. I patched the unit into the vocal-channel insert, dialed up the Vocal 1 preset, and just went with it. The results were impressive. I had originally intended to do a multitrack mix sometime after the broadcast, but the band members loved the sound of the live mix so much that they decided to do a release directly from the stereo DAT. They mentioned how good the vocals sounded; indeed, the vocal track sat nicely in the mix, sounding fat and warm.


A compressor with presets and a manual mode brings up an interesting question: which should you use? That is, do the presets somehow coax performance out of the box that you can't get using the manual controls? Or are they merely for convenience?

The Fat Man's operating manual provides a chart detailing the parameter settings for each preset, so it was relatively easy to compare manual settings to presets. The Fat Man's presets are certainly a handy feature, especially for novice users or situations that preclude time for tweaking; nonetheless, experienced engineers will probably want to skip the presets. Not surprisingly, the unit provides more control in Manual mode. Besides, the action of the compressor and the tone induced by the tube ultimately depend upon input levels and gain settings, neither of which is under control of the presets. Even if a quick preset is all that's desired, you still have to consult the preset chart if you hope to approximate the results the manufacturer had in mind. After all, the folks at HHB have no way of knowing the input level of a given instrument.

In general, the chart provides good starting points for gain settings when using the presets; however, I was surprised by the amount of makeup gain suggested for certain presets. For example, the chart recommends 12 dB of makeup gain for the Bass 2 preset — an amount that added too much hiss. It sounds as if the makeup gain circuit may have a boost in the high frequencies, perhaps to restore some top end lost during the compression process. Even if that's so, it's no problem. Makeup gain is typically the last thing you fine-tune, and you don't have to use as much as the chart suggests. However, I used the hiss from the makeup gain to good effect, as a sort of high-end restoration feature, a great deal more than I worried about the circuit details.


For sound quality, it would be hard to find a better unit in the Fat Man's price range; still, certain features are absent, most likely dropped to cut costs. The Fat Man does not have a sidechain input, for example, which means no de-essing of vocal tracks. Without a sidechain, it is impossible to set up guitars so they duck in level when vocals come in.

Another feature I missed was control of left and right channels. The Fat Man is a stereo-linked device, so it's not really appropriate for processing two separate instruments. Just the same, in the interest of pushing the envelope, I tried using it that way. Everyone gets into a tight mix now and then with too few compressors at hand, so I wanted to hear if the Fat Man could sit on two sounds at once. Kick and snare drums were obvious candidates for that work-around application, because they often alternate rhythmically.

I began with the Kit preset but eventually settled on Manual mode, which let me adjust the threshold for the desired amount of gain reduction. The results were quite good — at least until the kick drum hit during a slow snare roll, causing the snare to dip in volume. I wouldn't recommend trying to process two different instruments through the Fat Man, though it's good to know it can be used that way in a pinch on kick and snare — as long as the song tempo and drum pattern allow for it.


I was pleased with the Radius 3 Fat Man's sound quality and versatility. The unit has many uses besides the usual mono/stereo compressor duties. Its DI inputs, for instance, let the unit act as a tube stage with compressor and as a splitter (for example, to send a bass signal to an amp and direct to tape simultaneously through the rear-panel outputs). You can also use the Fat Man simply as a tube stage for adding drive and harmonic distortion to a signal.

Thanks to its 15 presets, the Fat Man is a great box for first-time compressor owners. The presets not only make setup easy but also cover a range of applications and are, for the most part, well formulated. The manual explains compression well and details the settings of each preset, which should prove helpful for educating novice users. Despite its unusual size and shape, the Fat Man is solidly built and a cinch to operate.

David Ogilvy is a producer and engineer in Northern California.


Radius 3 Fat Man
stereo tube compressor



PROS: Affordable. Presets allow quick setup. Provides soft- and hard-knee processing. Useful as instrument DI. Tube provides warmth to signal.

CONS: No XLR connectors. Linked stereo channels prohibit independent channel processing. Inconvenient size and shape.


HHB Communications USA
tel. (310) 319-1111
e-mail sales@hhbusa.com
Web www.hhbusa.com

Radius 3 Fat Man Specifications

Inputs(2) unbalanced ¼" TS (instrument); (2) balanced/unbalanced ¼" TRS (line)Outputs(2) balanced/unbalanced ¼" TRSOperating Level+4 dBu or -10 dBu (switchable)Input Gain Range±20 dBOutput Gain Range±20 dBMakeup Gain+20 dBFrequency Response5 Hz-40 kHz (+0, -3 dB)Total Harmonic Distortion0.5% (typical) @ nominal levelThreshold+10 to -20 dBRatio1:1.5-1:30Attack Time0.5 ms or 5 ms (switchable)Release Time0.2 sec or 1.5 sec (switchable)Dimensions5.2" (H) × 8.4" (W) × 8.3" (D)Weight5.5 lbs.