OPTICAL COMPRESSORS – A HISTORY
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April 9, 2009 at 8:29 am #15171
A SHORT HISTORY OF Ted’s Optical Compressors.
The first stereo optical compressor was designed in 1993 as a result of a little project to make a ‘travel video’; I did not have a nice sounding compressor in my roomful of old recording gear, so it seemed like a good idea to see if some of those old designs of the 60s still had any merit……. The result was a few days intensive development and using some modern ways to approach old problems, I came up with a stereo compressor that had the ‘weight’ and ‘urgency’ of those old Fairchild units, but in a stereo form.
The story about the colour is true….. I was about to take a prototype to a London Studio and it was housed in a nasty looking aluminium chassis. It was late in the day and I drove into Newton Abbot to a car accessory store to buy some spray paint. I asked for something really hard and durable but quick drying, the disinterested assistant reached behind him and handed me a can of bright green ‘Hammerite’…….. Everyone hated it, but it stuck!
The first production compressors, a batch of 50, were made with beautiful machined front panels, finished in the hideous green and each one lovingly hand wired. I still have 2 of the originals… both working.
Those front panels turned out to be ruinously expensive; they were painted by a coachbuilder, rubbed down between each of 6 coats of paint.
The second batch, introduced late in 1994 were called SC2 V1.02 and had more conventional front panels. They were still hand wired, and small modifications were made during 95 and 96.
The SC2 V1.05 was introduced in December 1995 and the V1.07; the last version using an input PC board and a separate compress/output PC board was introduced in 1996 and was current until mid 1998.
I made the first compressors specifically to work as volume compressors for complete music tracks. They were slow in operation, but had the attack and release curves that gave a lift to almost any music.
Most of those early SC2s went to studios in the USA where they were suddenly very popular as drum sub-group compressors.
The JoeMeek brand was starting to do very well by mid 1998 and the demand for the SC2 kept rising. To improve the reliability and repeatability, I re-designed the inside of the SC2 using a single printed circuit board and started to use a superior pot type (Alpha pots rather than the awful ‘Omeg’ types), and better switches: Any stories about the quality of production dropping at that time are totally false, the reliability improved and apart from some disastrous shipping problems where many mic amps arrived in the US smashed, the product quality was very good.
The circuit design of the SC2.2 was kept as closely as possible to the earlier SC2. I extended the range of the attack and release controls and added a stereo output gain control and a balance control.
Operationally, the 2.2 was certainly not as easy to use as the original SC2, where it was impossible to make it sound bad! However, the 2.2 did become one of the most popular pieces of outboard gear of the time.
Early in 1998 I designed a version of the SC2.2 with an integrated digital board. The digital circuitry was designed by my old friend Steve Dove. We made a prototype run of these compressors…. Called the SC3, but they were not popular and were superseded by the SC4 (October 1998), a similar design but with a plug-in digital board.
These compressors both retained the sound of the early SC2. I designed them as ‘end of the chain’ compressors in a mastering set-up, but they did not achieve much favour…. Most engineers wanted the conventional SC2.2
Both the later SC2.2 and the SC4 made use of M/S matrix techniques…. This is changing the ‘left and right’ into ‘sum and difference (M/S)’ and then compressing the signals before converting back into ‘left and right’. The huge advantage is that even under the heaviest of compression, the image stays constant, with no drifting of the centre. A secondary, but equally important advantage is that it allows the use of a ‘width’ control; wonderful for controlling the stereo image.
These compressors continued in production until 2001 when, following ‘9-11’, the equipment market in the USA stopped completely.
Commercial pressures meant that we had to close the JoeMeek company and the trademark was bought by the US distributor PMI.
PMI made the decision that all the old designs were out-of-date, and they introduced a complete range of very efficient, but not too exciting versions using the old product numbers, made in China.
In 2003 I introduced the first of the new TFPRO compressors, the P8. This was a new design based on 1960s principles but using a later type of optical device than on the SC2….. My own research showed that I could achieve the exact performance of the SC2 with these later devices, and also emulate some other compressors at the same time.
The P8 was a development project and few were made, but it quickly converted from it’s fire-engine red, with a single meter, to the P38, a much more refined two-tone blue with twin meters and classy aluminium knobs.
The P38, still in production and doing very well indeed, has become the classic optical compressor with the heart of the old 60s designs but with enough control so that it can perform many compression functions.
It might be a slight pity that the original ‘turn the knob and it works’ attitude has gone, but the P38 is still remarkably easy to use, and quite difficult to get wrong.
With the increased sophistication of mastering set-ups, I began to get a number of calls asking for additional facility…. Specifically side-chain access and ‘partial compression’.
The first was easy, that was just adding a little circuitry and a couple of sockets.
‘Partial compression’ is surprisingly more difficult as it involves a separate mixer stage. I looked at this possibility, redesigned the printed circuit board and produced the ‘extra’ version….. the P38EX
In terms of performance, the P38 and EX version are versatile in the extreme.
The new tfpro compressors use the same optical principle as the earlier Joemeek compressors, but with a very much faster operating optical device…. which I slow down electronically to get the same performance as the earlier ones. In addition, I use a separate parallel optical system to drive the compression meter, unlike the JM units, and also some radical work in the circuitry to get the extreme variable ratio, something that was impossible a few years ago.
The P38EX when switched to ‘Greenbox’ and the ratio set at about 5:1, with mid to long attack and fairly short release is a fine example of a compressor identical to the old SC2, yet with a cleanness that would not have been possible with old gear.
©2009Ted FletcherJune 23, 2011 at 4:39 pm #15485
AN UPDATE….. AND SOME EXTRA INFO.
Since writing that last piece I decided to look again at the ‘easy to use’ aspects of compressors based on experience with the very successful P38EX. I found that I never used those additional functions in the ‘EX, the partial compression and the sidechain access…. Partial compression is already there in optical compressors, it’s just how you use the ratio control! So I played around with a simpler design with some very old fashioned optical cells and came up with the P38V7. This is a P38 but with a heavier sound style and also a good clunky relay operated hard-wire by-pass. Maybe I’m getting old but I love it!
The P38V7 became available in May 2011.
The extra info is that looking back through the archives I found that the old JoeMeek SC2.2 did actually have a hard-wire by-pass…. a simple switch type that worked well. I dropped that function on later types.
Now, in July 2011, we are stocking the P38V7…. which is finding great favour in European studios, but also building a few P38EX for the ‘experimenters’ who want to play with effects in the compression sidechain.November 3, 2011 at 5:50 pm #15484
I suppose I shall have to keep updating this thread!!
In my own studio/workshop, I have a collection of old gear, and back on a hot day in August (2011) I decided to ‘run up’ some of the old compressors and check them against the latest ones.
The oldest one I have is the original prototype SC2… it’s actually the one that I spray-painted livid green. The next one I have is one of the early V1.05 SC2s with its beautiful machined front panel.
I ran these up with a selection of source material and was immediately surprised by how slow they were…. how gentle and ‘heavy’ sounding. When I tried the same material through a P38 I had to increase the attack time and adjust the release very carefully to get the same ‘slow’ sound. The P38EX was the same, but the later V7 had the edge on ‘heavy’ sound……. So I had a thought…… Why not go back to those optical components that we used to use? They are not as quick, so will not be good for the faster type of compression used in modern mastering, but that old optical sound is very subtle and maybe we need a compressor that is as easy to use as those very early ones.
I spent about four weeks playing with circuits old and new, there are so many aspects to design! But I convinced myself that what I really needed was a re-creation of one of those early compressors of the 1960s….. and for me as a real old lag, this was not too much of a problem!
To cut the story short, I ran some material through some circuits on my bench and let Dan, my son listen; his reaction was, ‘wow, it’s like a blast from the past… a legacy!’
And that’s how the Legacy was born.
I wanted to make a compressor that was affordable, so I kept the design simple, using only the controls and indicators that are really needed. Dan did the design of the front panel and it’s really beautiful; it matches the sound.
So now we have four separate compressors, the P38, the P38EX, the P38V7 and now the P38V8. They are all different, I love them all of course, but of course, the V8 being the ‘baby’ is my favourite for the moment.
If I was handed a tricky mastering job I would probably plug in my P38EX. If it was a rock and roll master that needed sharpening up, I would use a P38 or a P38V7, but I would also have a Legacy’ hanging on the output….. it has that amazing ability to sound great even when it’s doing almost nothing.September 2, 2014 at 10:13 am #15486
And now in September 2014, times have moved on again. I have stopped making equipment except for just one or two P38EX compressors…. that was the one that has stood the test of time.
It’s true that every successful piece of equipment that I ever designed was conceived as something that I needed myself. The P38EX is a direct descendant of the original JoeMeek SC2, and I suppose it says something that the mastering rack I have today contains both a P38EX and an SC2!
I occasionally tinker with plug-ins in my Protools trying to make them sound the same as the SC2 and sometimes they get close, but the great thing about the old green box is that you leave it plugged in and it always sounds good.August 24, 2015 at 9:13 am #15487danmcbParticipant
Ted, this is fascinating information and thank you for sharing it!
I’ve been playing around with the design of an optical compressor of late (something I have been curious about for some years, since I first designed more mundane ones around SSM2120’s some years ago) – after a few months I think I have something that sounds pretty good. I was quite proud of myself for figuring out what I though was a fairly novel topology – then I did some googling, found some Joe Meek schematics online and discovered … well … nothing new under the sun! You were at least 20 years ahead of me
Oh well, I guess what sounds good just … sounds good.
Anyway – thanks for being so generous with your knowledge and expertise!March 30, 2016 at 3:10 pm #15488
And now it’s April 2016!!
Nothing stands still, and I have been working on a new/old compressor…. well, not quite; it’s a ‘voice channel’, that is, a mic amp, a compressor and a harmonic enhancer all in one unit. It’s about the size, shape and weight(!) of a house-brick but departing from any tradition of mine, it is coloured a very pale creamy white.
Technically, it’s the best of what has gone before; it’s a transformer mic/line input into a class-A mic amp and then into a very TF traditional optical compressor.
A harmonic generator can add or subtract from the audio, so it’s both an enhancer and an unusual type of de-esser, but one that does not mess up the frequency response!
It will be on the market at the beginning of June, or maybe before as I have the first production prototype in front of me as I write this.
It has been difficult to keep up with the design demands of my ‘other business’, the business of good quality loudspeakers to improve domestic TV, and to make things slightly easier and more logical, we are amalgamating the businesses…. TFPRO will become a professional arm of Orbitsound. So the new mic amp/compressor will be called the Orbitsound TDC…… that is ‘Ted’s Definitive Channel’ (oh no!)
It will be advertised very soon!
😯June 3, 2016 at 9:21 am #15489jimmy deeParticipant Hi there..
when is the voice channel ready to buy,and whats the retail?June 3, 2016 at 9:52 am #15490
The new TDC ‘Voice Channel is actually ready now, but I’m still doing extended tests on it in Guy’s studio here in Aldwick Bay.
I do have a pricelist for the TDC…… email me on
firstname.lastname@example.org I will send it to you.
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