Lexicon PCM60 Refurb

Overview Back in 1980’s I could only dream of a Lexicon reverb, slim expensive 1U rack FX’s that lived in Pro recording studios. My first FX unit was (IIRC) an ART reverb which was quickly replaced with an Alesis Quadraverb, which served me well for 10 years in the 1990’s. During 2000/2010 I downsized the studio and had no need for FX, even a TC3000 only lasted a year. New synths around this time tended to have in built FX.

In 2017 I built a new studio space with room for some outboard. I was fortunate enough to buy both a PCM70 and PCM80 from a couple of old recording studios that were closing down, one of them in France. These are the back bone of my reverb setup, along with an old Yamaha REV7, which I first saw in a recording studio in Reigate in the mid 80’s. Gated Reverb – ha!

Whilst the PCM70 and 80 have some great reverbs, they are more useful during mix down, rather than for tracking synths. They stay hooked up the the analog console as outboard. For tracking synths I prefer older Roland SDE delays which sound like refined tape delays, a refurbished Quadraverb or my newly acquired PCM60 reverb.

Lexicon PCM60 The advantage of the 60 is you get two reverb algorithms derived from the legendary Lexicon 224 (Room and Plate) with just 4 time delay settings and on/off low and high EQ. No presets, everything is real time button selection, no deep spaces to get lost in – just rooms. The 60 also has an effects send and return which means you can patch in a delay or EG to further change the sounds.

It took me a few years to find one, and its not a perfect example by any means. But I finally have a PCM60 which I use with my “Big Moog”, its patched into the 984 Matrix Mixer, whilst the PCM60 effects loop goes of to a SDE1000 Digital Delay. I prefer to print sounds and FX on the way into my DAW, rather than in post production.

PSU Recap

Refurbishment Outside the PCM60 needed a clean, and there is writing underneath the buttons where someone has recorded their patch settings. Unfortunately this permanent ink will not come off and is embedded in the now faded blue part of the panel. I will have to live with this, unless I can find a better panel in the future.

Electronically the PCM60 works well with only two issues; The input level pot is worn and jumps to maximum causing a lot of distortion as the input stage is overloaded. Fortunately a similar pot is still available from Mouser, so I replaced it. It is not a perfect match; the pin out is further forward and the shaft a slightly smaller diameter. The knob is also a very tight fit, but it works.

The second issue is that one of the signal level indicator LED’s is not working. I suspect this is a problem with the LM3915 driver chip which is socketed, so it was easy for me to replace it. However the problem was a LED failure, so I replaced all the green LED’s, as the modern LED’s have a slightly different colour. Its easy to remove the LED PCB from the front panel and swap the LED’s.

The Lexicon components are high quality and the PCB layout is excellent. The power supply capacitors date back to 1984, so I have replaced them with new Panasonic high quality versions. I am pleased with the sound and noise floor, so I haven’t made any Op Amp changes which would be; FET input and output S&H to AD823,  Bipolar input/output to LM4562.

Outcomes The PCM60 is very well engineered, cheaper and rarer than the well loved PCM70, with two sets of sound that are very nice for vocals and drums. I use it with shorter percussive synthesizers sounds rather than for big ambient pads, which need longer reverb times from my PCM70 and 80.

There is a set of version 2 ROM’s that replace the Plate reverb with an Inverse Room, which was popular back in the 1980’s, but rather a cliché now. The V1.0 ROM’s are 24-pin 2732’s and the V2.0 is 28-pin 2764, they can be kludged together and manually switched but the Inverse Room is not worth the bother and cost.