HHB designed the Radius series of tube processors for personal studios and budget-conscious commercial studios, aiming for a balance between affordability

HHB designed the Radius series of tube processors for personal studios and budget-conscious commercial studios, aiming for a balance between affordability and professional sonic performance. Both the Radius 20 tube parametric equalizer and Radius 30 tube compressor are designed for warming up signals during tracking to digital multitrack tape or hard disk. However, these signal processors could work equally well for analog recording and live sound reinforcement.

These HHB products compete with a veritable flood of tube-based processors that have gained popularity since the ascension of affordable digital recording. It seems we all want tube gear now; let's see whether the Radius 20 and 30 fill the bill.

BIRDS OF A FEATHERThe Radius 20 and Radius 30 share many common traits, such as basic design, sonic performance, size, weight, and color (see the table "Radius 20 Specifications"). Both units employ hybrid solid-state/tube circuitry. Balanced XLR and unbalanced 11/44-inch I/O connectors are provided on the rear, and 11/44-inch instrument inputs for each channel are thoughtfully and conveniently included on the front. The inputs and outputs have level switches on the back that add 14 dB of gain to the signal (bringing the balanced XLR signals up to +18 dBu), which makes it easy to integrate the units into studios that mix professional and semiprofessional gear.

Both the Radius 20 and Radius 30 provide input controls that govern how much tube coloration they impart to the signal. A yellowish-orange Drive LED lights as the gain increases between 0 and +12 dB, while a red Peak LED indicates that the signal is within 5 dB of clipping. Dedicated output controls, in concert with the input- and output-level switches, provide versatile level matching between each unit and a variety of other equipment.

The manuals are brief-only a few pages long-and contain little information beyond basic operating instructions. However, most essential data can be found in the literature, and the units are easy to operate for those with experience.

EQUAL RIGHTS (AND LEFTS)The Radius 20 provides two channels of fully parametric EQ, with four overlapping bands for each channel. All bands are peaking only, meaning there are no highpass or lowpass shelving features. However, each band has a variable Q (bandwidth) control that is adjustable between 0.5 and 5 octaves. Each channel has an EQ On button, with accompanying green LED, that engages the filters.

Operation is straight-ahead. The rear-panel balanced XLR (+4 dBu) and unbalanced 11/44-inch (-10 dBu) inputs are available simultaneously. The front-panel instrument inputs override the rear connections so you can quickly plug in a guitar, synth, or other source.

FILTER BLENDThe Radius 20 is a great-sounding and versatile equalizer with enough overlap between each band to achieve some serious tone shaping, especially given that each band provides up to 15 dB of boost or cut. The wider Q settings sound smooth and full, especially in the upper bands.

I loved the Radius 20 for opening up the top end on everything from vocals to keyboards to drum sounds. The narrow bandwidth settings aren't as surgically precise as those on a digital equalizer, but they do an excellent job of notching out problematic frequencies in instruments like bass or overly sibilant vocals. The Radius 20 is particularly quiet for a tube EQ, even when bands are boosted quite a bit.

Depending on the source, you can color signals to varying degrees just by running them through the Radius 20 and adjusting the input drive into the tube stage, even with all the EQ bands set flat. When used in moderate amounts, this results in a perceptible blossoming of the sound that flatters a lot of instruments. I noticed a fuzzy, unfocused quality to the sound whenever I used too much drive, especially when using enough gain to illuminate the red Peak LED. I don't think the Radius 20 is at its best when used as a deliberate overdrive stage, but I like the quality it imparts to most signals at lower gain settings.

Just about every instrument I tried sounded good through the Radius 20. I spent a lot of time reequalizing some acoustic guitars that had previously been cut flat to ADAT, and I really liked the sounds I got. Both male and female vocals sound great through the HHB EQ, and I think it would be an excellent budget front-end EQ for vocal tracking. I especially loved the warmth and character it added to digital synths and samples on their way to being recorded.

The Radius 20 can be subtle or bold, depending on the settings, and I like that very much. By comparison, most digital EQs don't have character, and some analog EQs have too much of a sonic signature for my taste. The Radius 20 falls in the middle and is capable of mild corrective filtering as well as unique coloration, especially when you experiment with different combinations of the I/O knobs and level switches that affect the tube drive. It's not quite up to creating extreme, techno-style synth filtering, but that's not its purpose. I would use the Radius 20 for just about anything except mastering.

A FEW COMPLAINTSThe Radius 20 sounds wonderful, and its basic operation is simple. However, a few ergonomic issues started to bug me over time. The silk-screened panel information is small and not that easy to read (on both units), and the markings display minimal reference points. For instance, the high-frequency control of the Radius 20 displays frequency points only at 3 kHz, 6 kHz, 12 kHz, and 20 kHz. Although there are dots in between each of the designations, that's a lot of range to cover with one knob. You could easily boost at 13 kHz on one channel and mistakenly boost at 14 kHz on the other channel without knowing it. For this reason, the Radius 20 wouldn't be my first choice to equalize a finished mix or submix where left/right frequency and phase balance were critical. In addition, the knobs are all the same color, making it easier to grab the wrong parameter when you're working in a hurry.

Although the knobs appear to be of good quality, the switches feel somewhat flimsy; in fact, the power switch on the Radius 20 review unit was stuck and had to be cajoled to the off position. The same type of Alps Spun switches are found on many other pieces of audio equipment, and they would probably not pose a problem in a studio setting or gentle sound-reinforcement environment, but I question whether they could withstand sustained abuse on the road.

PUTTING ON THE SQUEEZEThe Radius 30 tube compressor employs the same basic design as the Radius 20 EQ. The I/O configuration is the same. The input controls drive the tube stage and the output control affects both the flat and compressed signals equally. However, the Radius 30 thoughtfully provides a 0 to +20 dB Gain Makeup control, allowing equal-energy comparisons between the processed and unprocessed sounds. The channels can be stereo-linked, meaning that the signal on one channel triggers the compressor for both channels, but each channel's settings (threshold, ratios, I/O levels, and so on) remain in effect.

You can stereo-link the channels so that the same amount of gain reduction is applied to both channels. However, unlike most stereo compressors, you can set parameters other than ratio (such as threshold, attack, and release) independently for each channel.

The threshold is variable between +20 and -20 dB. The unit is sometimes finicky when you are trying to tailor the threshold, because you have to keep in mind that the settings of the input-gain knob and level switch directly affect the overall timbre as well as the operation of the compressor. A few times, I wished the threshold range extended another 10 dB in each direction to fully accommodate either very clean or very hot input settings. I could usually find settings that worked well for most instruments; you just need to bear in mind that the input knob, input level switch, threshold, and gain makeup all affect the tonal character as well as the response of the compressor.

The ratio parameters are reversed from the norm in the United States; for example, a 10:1 compression ratio is expressed as 1:10, which Americans interpret as an expansion ratio. In addition, the lowest ratio available is only 1:1.5 rather than 1:1 (which would allow you to add tube coloration without affecting the dynamic range). The highest setting, 1:30, is plenty for most limiting applications. At certain ratios, especially those under 1:5, the Radius 30 seemed milder overall than most compressors. The knob markings on the Radius 30's front panel suffer from the same minimalist approach found on the Radius 20: ratio settings of 1:1.5, 1:5, 1:10, and 1:30 are the only markings besides a dot centered between each designation. For high ratios, that's not a problem, but I would prefer more precise markings between the crucial ratios of 1:1.5 and 1:5.

INSTRUMENTS UNDER ATTACKThe attack and release times are switchable between only two settings: fast and slow (see the table "Radius 30 Specifications"). However, these are program dependent: the attack and release times are generally shortened by fast transient signals.

Although the settings sound tailored for, and work well with, instruments like guitar, piano, and voice, the available attack and release times aren't ideal for every situation. This makes the Radius 30 a dubious choice for certain instruments, especially sounds with very fast attack transients, like drums. A certain smoothing of the transient through the tube stage takes place, which can be cool, but I didn't care for the sound of drums compressed through the Radius 30.

Although I never got a synth bass sound that I truly loved, the Radius 30 fared very well with a real bass guitar using the fast attack setting and slow release. Boosting the input drive a bit also matured the bass tone, which I passed through a Countryman direct box on the way to the front-panel instrument jack of the Radius 30.

I liked the sound of vocals compressed with the Radius 30. Vocals seem to be an ideal application for this compressor, although you have to hit the unit harder and at a higher ratio than your instincts or experience might indicate. At moderate input levels-enough to light up only the orange Drive LED-the Radius 30 can eliminate a lot of the harshness associated with some condenser microphone and digital recorder setups, and this feature alone may justify its use.

Although the Radius 30 seems to command a "turn the knobs and listen" approach rather than adjusting by the numbers, the compressor gives you enough control to shape some nice tones from a variety of instruments. I like that you can adjust the gain makeup to allow direct comparisons with the uncompressed signal (which are very important to make). The VU meters can display output level, in addition to gain reduction, making it easy to roughly match compressed and uncompressed levels.

CLOSING THE GATEThe Radius 30 includes a rudimentary expander/gate. One knob alone controls this feature, which amounts to adjusting the threshold until the Gate Shut LED lights up. The expander/ gate functions as you would expect, muting the signal entirely during silent passages.

Although I rarely employ gates when I'm recording, I've found that they are good for some applications, such as a noisy electric guitar rig. No envelope parameters are available for the Radius 30's gate, so initial attacks are sometimes lost on sharp transient material (such as drums) as the gate opens up. As with the compressor attack and release times, the gate feature seems tailored for vocals and other instruments that have mild envelope shapes.

ON THE SIDEThe Radius 30 provides two 11/44-inch TRS sidechain inserts, one for each channel. The level of the send is affected by both the input control and input-level switch, so it is very versatile and can be patched to a variety of professional and semiprofessional gear. Once again, you may have to twiddle with the various gain stages to optimize the compressor's operation, send/return levels, and overall tonality of the source.

I created a very compelling vocal sound by using channel 1 of the Radius 20 equalizer to contour the compression response of one Radius 30 channel via its sidechain. I then equalized the signal through channel 2 of the Radius 20, which flowed back into the remaining channel of the Radius 30 for overall level smoothing. I kept all of the input gain levels on the low side (lightly hitting the orange LEDs), and the accumulation of tube stages gave a full and earthy character to a female vocal. Though not pristine or pure, it was a great sound for a rock or alternative voice. In a more complex signal path like this, the variety of tube coloration available at the various stages can provide some very interesting sonic characteristics.

FINAL STAGEBoth Radius processors offer a lot of processing power for the price. They are especially quiet considering that they employ tube stages. Used in moderation, the tube stages add some color and interest to most sounds, although I don't care for their sound when the tubes are pushed too hard. The various stages of I/O level control make both units very flexible for interfacing with other gear, and the front-panel instrument jacks make them even easier to hook up.

If I could buy only one of these two devices, I'd take the Radius 20 over the Radius 30. I think the Radius 20 is an excellent and versatile equalizer, capable of subtle to rather bold tonal shaping. There is very little to criticize, other than its delicate switches, especially considering that the street price makes this almost a no-brainer. I wouldn't hesitate to use the Radius 20 in a professional application.

The Radius 30 is good for certain applications, such as smoothing out vocals and guitars, but I wouldn't choose it as my sole front-end compressor to a digital recorder. Not only is it not quite versatile enough, it also seems too mild as a compressor unless you really pour it on. However, one of my guitarist friends liked the Radius compressor better than the equalizer. Go figure. Furthermore, the two devices work extremely well together. Considering their competitive prices, they both deserve a test-drive when you're in the market for tube processing.

Producer and songwriter Rob Shrock is the musical director for Burt Bacharach. However, being an electronic musician, he was the only member of Bacharach's band not in the Carnaby Street scene in Austin Powers: The Spy Who Shagged Me.