Oram Octasonic Precision

Oram are not a company to do things by halves; their Octasonic, as the name suggests, features a whopping eight channels of professional‑quality mic amplification. David Mellor finds it's eight times a preamp...

Outboard microphone preamps are common in the pages of Sound On Sound these days, and despite the fact that anyone with a mixing console already possesses as many mic amps as he or she could possibly use — without buying a bigger console — these products seem to be selling, and selling well. There has to be a good reason for this, and in fact there are at least three. Firstly, although the mic preamps in modern mixing consoles are usually good, there is still scope for wondering whether they are actually great. Secondly, even though the mic amps in some consoles may be excellent, for the producer or engineer moving from studio to studio, consistency is vitally important. A third reason for having an outboard preamp is to make recordings on location without having the burden of a mixing console to carry around.

Physically

The Oram Octasonic is an 8‑channel mic preamp designed by the "Father of British EQ", John Oram. I'm tempted to wonder whether, if this is designed by the father of British EQ, it's going to be the mother of all mic preamps, but we'll see about that shortly. John Oram, in fact, has a long history of success in the audio industry, although it's comparatively recently that he's built products under his own name. The old Trident mixing consoles on which Oram worked are regarded almost in the same league as old Neve consoles, so we should be able to expect something rather special.

Physically, the Octasonic's 1U rackmount case has a solid, chunky feel. The power supply is built in, as you would expect from a unit in this price range, and the mains inlet is prominently marked '230V' to remind us of the new nominal UK mains voltage. It works fine with the 240V we still actually get. The inputs are all on XLR connectors, while the outputs are on balanced jacks. Inputs and outputs are very clearly numbered, as they should be, since the channels are reversed when you look at the unit from the rear. The top plate of the unit is held in place in part by some curious plastic fasteners which have to be prised off to release them — not that you'd have to, since there are, fortunately, no irritating internal fuses to worry about. Still, I'm the type who always has to take the lid off and have a look.

Inside the Octasonic there's a lot of fresh air, actually quite warm air once the unit has been running for some time. I wondered at first where all the circuitry was and then, with the aid of my magnifying glass, I found a number of surface‑mount components. Surface mounting is a relatively new method of electronic construction, where the size of the components is minimised and lead‑out wires are absent. As a manufacturing technique it has advantages in speed of construction, cost and, of course, size. Sonically, I can't see any drawbacks, but if the unit develops a fault, repairing a surface‑mount board is a job for a specialist. Fortunately, Oram's service department offers 24‑hour board swap‑out in all the countries where their equipment is sold.

Conventionally packaged components are used as well, the active ones being a custom‑designed Analog Devices integrated mic preamp chip, and one dual op‑amp per channel, socket mounted. Technically, this is about as far away as you can get from the current craze for valves with everything. I could be tempted to speculate that if you already had a valve preamp, you should have one of these too, so that you have an example of both ends of the technological spectrum. Everything inside the Octasonic is very tidy, and the high‑voltage components are shrouded.

Aesthetically

The Octasonic is an interesting piece of equipment in terms of its cosmetic design. The blue colour is tasteful enough, and the knurled aluminium knobs give a solid, no‑nonsense feel, as does the fact that they lack skirts and the nuts holding the potentiometers in place are visible. The pots are 41‑position detented, which is a feature that some people like and some people hate. The detents in themselves mean nothing, as the track around which the signal flows is continuous, but it does mean that you won't move a pot accidentally as you press a button. The calibrations are small and not too easy to read under dim illumination, and towards the higher gain ranges small movements of the knob result in large changes in gain.

The two buttons in each channel are for phase and phantom power. The phantom power button is recessed, so you have to push quite hard to operate it. This is a good idea, since accidental operation of the phantom power switch during recording would be disastrous. I have said in the past that I don't see much point in having switchable phantom power, since any dynamic mic of professional quality doesn't care whether or not it is present (and dynamic mics don't need it), but as we shall see later, the Octasonic is a little bit more versatile than common‑or‑garden mic preamps, and you could, indeed, find a need to switch phantom power off. Beneath the two buttons in each channel are a couple of red LEDs, one indicating peaks, the other indicating phantom power.

Operationally

The Octasonic has two unusual features. Firstly, the inputs will accept very high‑level signals, as well as normal mic levels. Secondly, two of the channels are so‑called 'hot' channels, and can accept even higher levels. Apparently, Michael Jackson's engineer was consulted on just how hot a signal can get. Hotter than you could possibly imagine, it seems. A microphone may produce a signal level of up to around 0dBu (just under a volt) in response to a very loud sound at close range. The Octasonic's inputs will handle signals up to +22dBu, which is as high as you would get from most line‑level equipment, so you can plug in pretty much what you like and there won't be any distortion. On the hot channels, the maximum input is a whopping +34dBu. To put this into some lind of perspective, if a power amplifier produced an output of this voltage, into a 4Ω loudspeaker the power would be over 375 Watts! This is what I call hot.

The fact that two of the eight channels have a different gain structure is interesting. Channels 1‑6 have a range of gain from 0dB up to +70dB, while channels 7 and 8 range from ‑12dB to +35dB. My first thought was that I would have preferred all channels to be identical, as in other octal processing units, but on reflection I realised that there is actually no need for this to be so. In any real‑life recording setup, microphones with widely differing characteristics are used. The manner in which the mics are used will produce signals of vastly different levels, and it's perfectly appropriate for the Octasonic to make allowance for this. The hot channels will obviously be used for very loud sources — bass drums and operatic sopranos come to mind — and for mics that have a particularly high output level. I think it might have been useful for the hot channels to be visually differentiated in some way, since without actually knowing what was going on, a user could easily think that channels 7 and 8 were faulty. Currently the only difference is in the calibrations, which, as I said earlier, are not that easy to read.

Finally

The Octasonic, like all Oram products, has a feature known as Oram Sonics, in which low frequencies are delayed slightly, as explained in the 'Oram Sonics' box. This means that the Octasonic is not transparent but has its own character. Valves are known for giving warmth to a signal, and Oram Sonics adds warmth too, in a different way. The only way to appreciate it is to experience it, but it's certainly audible and, to my ears, has no negative side effects. As well as being a very good mic preamp, the Octasonic is apparently being used by a number of engineers in conjunction with the Alesis ADAT, to boost the ADAT's low‑level outputs to standard professional levels — even though the ADAT has pro‑level outputs built in. Strange but true.

I don't know whether it's a side effect of Oram Sonics, but one curious feature of the sound of the Octasonic is that the difference between correct and inverted phase is clearly audible even on a single channel (if one of a stereo pair of channels is inverted, you'll hear a massive difference with any equipment). Most people are virtually insensitive to absolute phase, but for some strange reason I found it remarkably easy to hear on this preamp, using a mic as the input and monitoring on headphones. Apparently I'm not the only one to comment on this either. Technical parameters such as frequency response (better than 18Hz to 73kHz), noise (equivalent input noise ‑127.8dBu @ 70dB gain) and distortion (less than 0.005%) are beyond reproach.

To sum up, I'd be very happy to own an Oram Octasonic. Its performance is excellent, the build quality professional, and the price per channel, compared to other outboard mic preamps, makes it very good value.