High Definition Equaliser The
'Hi Def'
PRO
RACKS
John
Oram combines the most contemporary features with his patented EQ Magic™
circuitry, into the most complete and flexible system available to date.
With the revolutionary use of combinable sweep and shelf equalisers, coupled
with sweepable high and low filters, the user has an available total of
eight (8) bands of control. Separate Filter and EQ bypass, as well as
selectable Bandwidth and Detail, further enhance total control flexibility.
Designed as a reference equaliser for the Media Mastering, Broadcast,
and Live Sound environments, the audio engineer now has an unprecedented
level of control with exceptional realism and fidelity.
As in all Oram sonics products, surface mount circuit technology and mil-spec
mechanical construction ensure ultra-high quality assurance and long term
reliability.
Dave Foister review of the HD-EQ 2
Keith Spencer-Allen's recent review of the Joe Meek compressor serves as a reminder that even in this hard-nosed age a name can still sell a piece of equipment. Rupert Neve's name, for example, will sell an equaliser design whoever has actually manufactured it, and the names George Massenburg, Ivor Drawmer and Clive Green continue to sell products. The latest name to bank on its own fame to promote its wares is that of John Oram, late of Trident consoles, who has launched a range of equipment under the banner of Oram Sonics. Each of the three current models is of interest as having something about it which sets it apart; typical is the VU-More metering module, which augments a pair of VU meters with red and green phase check LEDs and a feature for automatically displaying residual hum and noise levels during the gaps between actual signal.
John Oram goes so far as to describe himself in his company's publicity variously as 'the founding father of the "British Sound" in audio electronics and equalisation 'and 'the father of British EQ', and it is perhaps fair to make the connection between Trident's success and the popularity of Oram's EQ design. His involvement in the development of the legendary Series 80 and the TSM speaks for itself, and his stand-alone equaliser, the HD-EQ2, applies his years of experience to the problems of designing a versatile outboard EQ combining flexibility with a familiarly desirable sound. Oram has high aspirations for the unit; it is described as being 'designed as a reference equaliser for the Media Mastering, Broadcast and Live Sound environments' and the construction is described as 'mil-spec'.
There is no doubt that among the plethora of plainly-styled, hand-turned aluminium knobs there is little missing from the list of what one would ideally hope to find on an equaliser. The fact that this is a two-channel unit with so many facilities means it is not small - 3 units of and-sculptured blue aluminium are required to make space for all of the controls. The sculpting consists of bevelled recesses into which knobs and switches are set, and makes the push buttons safe against accidental operation without making them fiddly to use. This expanse of what is undeniably an unusual colour for an audio toy, together with the plain silver knobs and simple black and white push buttons makes the equaliser quite distinctive, although its individuality may not be to everyone's aesthetic taste.
The initial impression given by the controls is that they are arranged in a bit of a jumble, but in fact a closer look shows them to be very logically laid out. The main EQ path includes six bands, and the first distinctive feature is that rather than having high and low bands which are switchable between shelving and sweep operation, both are offered simultaneously. These are then augmented by high and low mid bands and all four swept bands are what one might call quasi-parametric. As far as I am concerned, an equaliser only gets the right to call itself fully parametric if it has an infinitely variable Q or bandwidth control. The variable gain and frequency are taken as read, but on their own constitute no more than a swept equaliser. The Oram EQ splits the difference by having a push button on each band to select narrow or broad bandwidth, and for most purposes this does the job. The actual Q values for the two settings are not specified, but the narrow is not too narrow and the wide is not too wide, and the characteristics of the two are usefully distinct.
The frequency range of the four swept bands overlap by an unusually sensible amount. Often adjacent EQ bands are designed to overlap so much that the range of each band becomes too great for easy delicate adjustment, but the Oram avoids this in favour of the detail provided by dedicated bands. The low goes right down to 35 Hz and the high right up to 18 kHz, so nothing is sacrificed in terms of overall range. This degree of frequency control is perhaps part of the justification for the unit's name-the HD stands for high definition-and the other part is the flexibility of gain adjustment. Boost-cut controls all have an adjacent DETAIL switch, which reduces the range of the control from +18 dB to +6dB, giving the possibility of much finer adjustment.
The shelving bands also have this Detail switch, but are otherwise much simpler. Shelf frequencies are switched rather than infinitely variable, with both extremes having three possibilities, again sensibly spaced to cover all eventualities-35, 60 and 200 Hz for LF and 3k, 6k and 20k for HF.
At the extreme ends of the bands of EQ are filters for the frequency extremes. They really are extreme-the LF goes down to 5 Hz while the HF all the way up to 80 kHz, which even Oram admit is outside the audible range, although I am sure that there are many who would claim sufficient importance for those frequencies to justify having control over them. Adjustment of both filters is infinitely variable, with a fixed roll-off of 12dB/octave, and at their inner limits they almost meet in the middle, leaving a band of 300-1500Hz.
Input gain controls with associated peak LEDs-lighting at +10dBu-precede the filters and EQ and although the EQ bands have a single overall IN-BYPASS switch, the filters are switched separately. A pair of bar-graph meters keeps an eye on the final output level. The rear panel is sparsely populated, having only XLRs for inputs and outputs, but Oram maintain that running either end unbalanced will give no problems. Oram's published specifications for the HD-EQ2 are a curious mixture of very impressive hard fact and subjective ideas which could be seen as controversial. For instance, the bypassed frequency response-which is not a hard wire- is absolutely ruler flat, with mid-band noise levels of-100dBu, but the response with the EQ switched in but set nominally flat is quite deliberately not. The deviation is very subtle-the response is within 1dB from 20Hz to 40HZ-but John Oram claims that the gentle droop towards the bottom of this range and the slight lift above about 10kHz is characteristic of Oram Sonics and is what gives his designs their distinctive sound. He predicts that the difference caused by this small deviation will make users want to leave the unit in circuit all the time whether actually using the EQ or not, and backs up the idea with exemplary noise and dynamic range figures which would make this less of an undesirable proposition than it might otherwise be. Not content with publishing simple figures for headroom and distortion, Oram provides graphs of such functions against frequency, showing that the unit will deliver +26dBu-balanced-right across the spectrum, and that THD+N at this level is less that 0.01% in the critical upper mid range. With worst case noise figures of -74dBu (all EQ and filters in circuit) this amounts to a technically impressive performance for six bands of active EQ, and the more subjective claims for the unit are easier to swallow coming from a man who can design like that.
And the result of all this design expertise is an equaliser that is a pleasure to use in all kinds of applications. I have never been much of a fan of graphic equalisers, much preferring the more flexible and to my mind more direct control of a well-specified sweepable design. The Oram HD-EQ2 provides most of the potential advantages of such configuration with the small omissions more than compensated for by the large number of bands, the precise control and the sheer quality, both objective and subjective. The possibility of every band having 18 dB of boost and cut affords the potential for quite vicious corrective equalisation, and yet it is very difficult to make it sound strained in any way. In fact it is possible to do quite radical things to the sound without the result giving away the heavy processing, so musical does the final output remain. Particularly impressive in this respect are the high and low-pass filters, which are the smoothest, least obtrusive I have heard.
At the other end of the spectrum of possibilities, the delicate control produced by using the DETAIL switches, in conjunction with the fine resolution of the frequency sweep controls, offers extreme subtlety (if that is not too much of a contradiction in terms) in dealing with the smallest nuances. Coupled with the excellent noise and distortion specs, this would make the unit an ideal choice for mastering applications and I should not be surprised to see a demand for a switchable version like that produced by Focusrite, to allow precise stereo matching specifically for this purpose. However accurately controls are calibrated-and it seems that the Orams's are very well matched-it is simply not possible to set two channels of continuously variable controls reliably to the same values. Whether the subtle effect of the 'Oram curve', when set flat is worth shouting about is a matter for debate; there is a slight difference switching the EQ in and out, but whether it is significant enough to warranty being made a feature of, particularly when some will object on principle to an equaliser which is not flat when it looks as if it should be, is questionable.
For general studio use all the above advantages apply. On a recent overdub session I ended up, just as the instructions said I would, with it left in circuit for everything I recorded. As much as anything, this was because its sensible control ranges make it extremely fast to set up and very easy to get good results with. Although it may seem a bit beneath its dignity, I used the EQ on a pair of Tandy PZMs stuck inside a grand piano, and the inevitable boxy lumpiness of this otherwise splendid technique was soon ironed out, giving the most natural sound I have so far managed to achieve with it. On more conventional microphone techniques it seemed unusually easy to lose that bit of room coloration, and to tailor, say, a vocal to the requirements of the track.
This is not a cheap equaliser, but neither is it as expensive as it might be considering its capabilities and sonic excellence, Judging by the way so many people complain about the EQ on otherwise superb desks, I am lucky in that I get on very well with the parametrics on my console, but the Oram is one of the few outboard EQs which I would quite happily use routinely in its place.
Dave Foister
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