A Brief History Of My ITI MEP-130 Mastering Parametric Equalizer Modules – Serial #001 / #002

ITI’s Beginnings

It’s crazy to think there was a time before recording consoles had EQ, not to mention parametric EQ. It all started back in the late 60s. Deane Jensen (yes, of Jensen Transformer fame) and George Massenburg (who later started George Massenburg Labs or GML) came to Burgess Macneal‘s studio in Maryland to help build a new console that was to have parametric EQs with independent control of gain, Q (bandwidth) and frequency for each band. Burgess got his recording legs by recording the Baltimore Symphony Orchestra as a teenager. That said, for it’s time having parametric EQs in a console was very novel and forward thinking. Soon after beginning on the console, in which they only ever made one, Macneal and his business partners decided to part ways and his Recordings Incorporated studio was absorbed by a company named ITI (International Telecomm Incorporated). Burgess Macneal was named Vice President. ITI was headquartered out of Hunt Valley, MD, just north of Mobtown. The EQ module for the console, the MEP-130 EQ had no fixed stops, making it theoretically practical only for tracking and mixing – but that never stopped anyone as it sounded so good. But as word spread of the new technology, ITI and the audio community soon realized the potential for the mastering market; the seed was planted for what would become the Sontec MEP-250. Sadly, the mixing console never went beyond prototype, but the MEP-130 EQ was sold as a console module very briefly and was repackaged and released as a stand-alone rack mount product in 1971 as the MEP-230A EQ, thus making the MEP-130 module and MEP-230 outboard unit the first commercially available fully parametric EQs. Like the MEP-130, the MEP-230 had ——three bands of fully parametric EQ, but with a 10kHz high shelf and a selectable 50Hz/100Hz low shelf.

Potted Op-Amps and Filter Blocks

The potted filter blocks that could not be replicated easily.


What was tricky with these EQs is that everything after the prototype had potted op-amps and filter blocks. That meant the amps and filter blocks were all covered in black epoxy potting compound. [See below.] They did this for two reasons. 1 – as a heat sink for output transistors and 2 – so people wouldn’t be able to steal the design. What it did mean was that you were able to replace the op-amps and filter blocks as they died, relatively easily and with out soldering. It was as simple as buying a new amp from the manufacturer and simply could swap a new one in. However, this assumed the company would be producing these amps in perpetuity. That or you ordered a stockpile. And tragically they stopped making them. So when the amps or filter blocks died, the EQ was a terribly unwieldy paper weight.

The Great Find On Craigslist

So this brings me to the summer of 2017. I saw an ad in Craigslist for an ITI EQ. It was listed as an “MEP-30 EQ” – which was a curious mistake that perhaps kept people from thinking it was legit. I thought I’d pick it up. Worst case: I’d get to see an early ITI EQ and possibly get some information about it. Best case: it was functioning and he had extra filters and amps. Turned out it was the MEP-130 Module EQ pulled from the prototype of the ITI console. I got to talking to the man (Doug) who sold it to me, and was able to pick his brain about how he worked with Burgess and actually worked on the ITI console and other varies sundries in the 60s/70s. He said the ITI console ended up in a houseboat that doubled as a recording studio. Sadly the boat sank and the console with all those ITI MEP-130 console EQs are at the bottom of the Baltimore Harbor. A few were salvaged. I reckon this EQ I bought was the last bit of evidence it actually existed. However, at this point I still didn’t even know if it passed signal or would kill me if I turned it on.

Joe From JLM Audio Restoration

So I decided on the gamble. I bought it and brought it home and of course being the tinkerer I am, I opened up the top panel and took some pictures of it and posted it to instagram. What felt like 30 seconds, but was probably a day later, I got an email from Joe Malone at JLM Audio. I’ve known him for a few years as I am a huge fan of his work at JLM Audio, so I took his email seriously when he was interested in my MEP-130 and especially the part about not plugging it until until the power supply has been fixed! ZZZZZZZZZzzzzzap! He very quickly realized from my photos that my ITI MEP-130 had un-potted op-amps and filters – hence the prototype. So you could actually copy them, rebuild them and then all those dead paperweights of a EQ could be brought back to life. So in the end, he was able to rebuild all the op-amps, he rebuilt the power supply using a new modern compact SMPS power supply with super filtering instead of the dangerous old power supply which would have needed a 2 unit rack high case just for itself, and put this half a century old baby back in a rack. And all your new songs can go through the ITI MEP-130 Parametric EQ Serial #001/002. I am pretty honored to carry such a wonderful piece of history that’s over 50 years old in my studio and will be sure to use it on your next record.

ITI MEP-130 Parametric Equalizer Channel Module – Technical Manual

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