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Phonic T8100, T8200 & T8300

Valve Processors
Published April 2005
By Paul White

Phonic T8100, T8200 & T8300Photo: Mike Cameron

This range of valve units offers a variety of character sounds for the more adventurous home recordist.

Phonic build a wide range of recording and live-sound equipment at UK prices that won't scare off the user working to a budget. In addition, their products generally offer a good level of performance. We're reviewing three of their T-series pieces of outboard here: the T8100 dual-channel mic preamp with EQ; the T8200 two-channel, split-band compressor; and the T8300 two-channel enhancer. All the units have a variable 'Tube Timbre' circuit.

T8200 Tube Optimizer

This unit has independent controls in each frequency band for compression, ratio, threshold, and (switched) attack speed, and the user can adjust the crossover frequency from 100Hz to 12kHz. The point in having a split-band compressor is that it enables the user to compress complete mixes without the bass end dominating what the compressor is doing to the high end. Normally a high-level bass sound, such as a kick drum, forces the compressor to pull down the gain right across the audio spectrum, thus affecting cymbals and acoustic guitars as well as the drums and bass. By splitting the audio into two or more bands and processing each separately, the low end can be kept under tight control without disrupting the high end.

As with the other two units in the range, the T8200 is a 2U processor and is generously equipped with eight retro-style, illuminated circular moving-coil meters showing the input/output level and amount of gain reduction on both frequency bands. These work fine, though the meter legending is ridiculously small. Connectivity is via both balanced jacks and XLRs, with separate switches to select between -10dBV and +4dBu operation for each input and output. The two compressors may be used independently or linked for true stereo operation. For all three units, power comes in via an IEC mains cable.

The level meters of the T8200 can be switched per channel to read either the input or the output level, while the gain-reduction meters always read the amount of gain reduction being applied in the relevant frequency band. When Link mode is selected, the side-chains are combined so that both channels are always applying the same amount of gain reduction at the same time. In linked mode, channel one's controls affect both channels. Both the high and low bands have their own Threshold and Ratio controls, while the Low Average switch sets the compressor's average attack time for the low band only to fast or slow. A similar High Average switch affects the high-band attack time. There's no release control and the documentation doesn't make it entirely clear whether the release time is fixed or programme dependent. It's also not made clear what type of gain-reduction element is used.

The low and high bands have their own level controls so the output can be equalised to some extent depending on the balance of high and low bands used. A rotary control adjusts the crossover frequency, which determines where the band-splitting occurs. If you just want to prevent the bass from affecting everything else, then 150-250Hz might be a good starting point, but you can also use the T8200 a little like an enhancer, by compressing only high frequencies and then adjusting their level in the final mix.

Another avenue of tonal tweaking worth exploring is the Tube Timbre control, which adds warmth in the form of subtle distortion (and seemingly some EQ) when turned clockwise. The specifications of all three units reveal a worthy 18Hz-30kHz frequency response (±2dB) and a noise figure of lower than -90dB. Up to +21dB is available at the output when working into a balanced load, and the output impedance is a robustly low 60Ω, so driving long cables should not be a problem.

Optimal?

As a split-band compressor, the T8200 Tube Optimizer is pretty easy to set up, and it has a good ratio range going right down to 1.1:1, which means it's suitable for gentle mastering jobs as well as for more aggressive individual track-processing applications. Despite having no release controls, it manages to sound natural and transparent, though if you want that 'larger than life' character, the Tube Timbre knob helps provide it. Having split bands is really effective in avoiding the compression artefacts mentioned earlier, which are often audible in full-band compressors where the low frequencies always call the shots.

While serious mastering engineers probably wouldn't use the T8200, it is capable of adding density and polish to finished mixes without choking the life out of them. It also works well as a routine tracking compressor, where you can also make it behave much like a full-band unit by setting the crossover point as low as possible. Overall this is a practical and easy-to-use processor that has a lot of worthwhile applications in the project studio, both for mixing and mastering.

Connectivity is via both balanced jacks and XLRs across the range.Connectivity is via both balanced jacks and XLRs across the range.Photo: Mike Cameron

T8300 Tube Enhancer

The T8300 is again a two-channel device, this time designed to enhance the low and high extremes of the audio spectrum. As with other enhancer-type devices, the high-end processing opens up the sound making it more airy and transparent, and there's a choice of enhancement characters. A Bass Timbre control determines whether the bass end will be solid and punchy or warm and deep, and the processing appears to be applied to frequencies below 100Hz or thereabouts. The connection and channel-linking options are the same as for the previous unit, as is the 12AX7 dual-triode tube inserted into the signal path to provide a user-adjustable level of Tube Timbre coloration.

Each channel sports two circular moving-coil meters to monitor the input and output levels. An Input Level control is available along with Bass Level and Bass Timbre controls to set the amount and type of low-end enhancement, though the Bass Timbre control has a bypass switch to disable it when added 'character' is not required. The high-frequency enhancement is controlled by a high-pass filter adjustable from 1kHz to 8kHz and the High Boost control determines the amount of HF enhancement added. A further control labelled Enhancer/Exciter determines the type and tonality of the high-frequency processing, though there's no technical description of what the circuitry actually does. Listening to it, I'd say the Enhance end of the spectrum sounds more like dynamic EQ, whereas the Exciter end of the scale is definitely adding distortion-generated harmonics. A hard relay bypass is available for each channel and there's also a separate control for adjusting the Tube Timbre. An output level control, clip indicator, and power switch complete the complement of controls.

Effective?

The Tube Timbre part of the T8300 Tube Enhancer behaves much as it does on the other two models, adding level, giving lots of low-end warmth, and opening up the high end in a musical and very obvious way — provided you don't add too much, in which case the sound simply gets messy. At the low end, switching out the Bass Timbre control allows the Bass Boost knob to work much like a regular bass EQ, whereas switching it in produces a more complex effect. When the control is fully anticlockwise, the bass sound seems tighter and more focused, while at the other extreme the bass becomes very warm and broad. All three options have applications both for treating individual tracks and complex mixes or submixes, but, as with the Tube Timbre control, they need to be used with restraint.

The same is true of the high-frequency processing, which is noticeably smoother in Enhance mode than in Exciter mode. In fact I'd say this is one of the most aggressive exciters I've heard, even when the filter frequency is set very high, and my own opinion is that the Exciter mode should be avoided when processing mixes, though it can work wonders in adding edge to a woolly snare-drum sound. For more subtle jobs, use Enhance. There's certainly a lot of scope for tonal tweaking here with the various enhancement modes and the Tube Timbre section. Although you can end up with a very messy sound if you apply too much processing, used with care you can coax some very worthwhile results out of this unit. The ability to use it as two mono channels is also very welcome when treating individual tracks.

T8100 Tube Vocalmax

Phonic's T8100 is perhaps the simplest device in the range, with two channels each comprising a mic/line preamp, a three-band equaliser, and the now familiar Tube Timbre circuit using one 12AXT tube per channel. Grilles in the front panel offer a view of the valve, and lamps are fitted behind the tubes for extra glow! The unit can handle signals via rear-panel balanced XLR or jack inputs, and the preamp gain is variable from 10dB to 60dB. A circular meter shows the input level, while a fast-acting clip LED warns of excessive peaks. The mic preamp has switchable phantom power and a phase-inversion facility as well as a switchable high-pass filter to cut frequencies below 100Hz.

As the EQ is designed for vocal sweetening rather than radical tonal shaping, it follows a straightforward topography with a swept mid-band and shelving filters at the high and low ends (12kHz and 80Hz). The sweep range is from 400Hz to 8kHz, and all three bands have a cut/boost range of 15dB. There's no EQ bypass button, which I feel is a bit remiss, but the cut/boost controls do have centre detents to denote the flat position. A further control sets the output level. From an operational point of view, I'd have preferred more range at the low end of the mid-frequency control, as being able to cut at around 250Hz can be useful in reducing boxiness in some sounds. Having the mic and line inputs on the rear panel can also be restrictive when the unit is rackmounted, as it's not always easy to access the back of a rack.

Maxed Out?

I checked out the T8100 Tube Vocalmax using an extremely quiet Sennheiser MKH40 microphone, which confirmed that the preamp was reasonably quiet and certainly perfectly acceptable for close-miked vocals and instruments, which is its main application. The mic gain tended to be bunched up towards the top end of the gain control, but not unmanageably so. However, I did notice a very dramatic change in timbre when operating the phase switch, but because you can hear odd effects of this kind when using your own voice as a source (due to the way the direct and amplified sounds combine), I double-checked using a different sound source. Sure enough the difference was still audible. Looking at the circuit diagram, I noticed that the phase-inversion switch comes after the tube stage, and as some of the tube signal appears to be routed directly to the output mix (according to the block diagram at any rate), this might explain the effect. Whatever the cause, you can't simply treat it as a normal, transparent phase-invert switch, and, worse still, I don't know which if either of the settings is tonally accurate.

Without EQ or Tube Timbre, to my ears the sound is clean but lacking in any real character or sparkle. Adding in Tube Timbre increases the level and also enhances both the low end and the upper harmonics, producing a far more friendly sound. If you like your vocals to sizzle, the high EQ control adds just the right amount of air to lift the sound out of the mix. A mild cut at 400Hz also sweetens things, though I found the EQ labelling to be a little confusing, as all bands were labelled as Peak, whereas the manual clearly states that the high and low bands are shelving. The high band certainly sounded like a shelving filter to me, but whatever the reality of the situation, the EQ is actually rather nice. In fact, the lack of detailed explanation in the manuals was a little frustrating, as I like to know exactly what my processors are doing. Even the block diagrams were ambiguous in this respect.

Overall Conclusions

This is an interesting range of processors, as the Tube Timbre circuit gives them rather more tonal flexibility than you might imagine. There are some quirks, especially the bizarre way the phase switch works on the mic preamp, but if you want to impose character on a sound rather than simply process it as benignly as possible, then these Phonic processors have much to offer. My personal favourite was the mic preamp, which despite some odd features was actually capable of creating a warm, airy, produced vocal sound, even if the sound was pretty lacklustre when everything is set flat.

I like the split-band compressor for its flexibility and simplicity, even though you probably wouldn't choose it as the only compressor in your studio. The Tube Enhancer was perhaps my least favourite, mainly because of the gritty nature of the high end added by the Exciter position. But even that can produce good results when used sparingly. The outboard market is pretty competitive at the moment, but these processors have their own tonal character to help them stand out from the crowd.

Published April 2005