tablebeast said:
I want to do the mods to the Altec because a friend bought one and has buyers remorse in stock trim. I told him the real mojo those are associated with is from the EMI modded ones, not the stock dogs. SO, I want to mod up this one and build my own clone into an Akai module as well. When I get the confirmed and proper EMI mods and then couple them with all the other useful mods out there I will also put THAT up on a full fledged DIY tutorial with pics, videos, recorded samples, etc.
I am 100% behind this effort. I've got a 436c that I've been trying to improve on for years - check my postings here for a partial history of that.
Certain parts of the EMI circuit mod (the RS124) can be deduced from what is publicly known about the faceplate - for example, replacing the release knob with a 12-position stepped switch for 6 different recovery times, with a "hold" setting (i.e. infinite release time) in every other switch position.
Other parts of the RS124 circuit have been publicly discussed but not confirmed. Plate balancing, cathode balancing, upping the coupling capacitor values.
The only people who know for sure are techs who have gotten to see the originals (Abbey Road engineers, and those who came sniffing around later). And those vary, unit-to-unit, as is explained by the folks at
Abbey Road plug-ins, who included switching between emulations of 3 different serial numbers in their plug-in. The design evolved over the years, back in the 60's, and so guess what?
There is no single "real" RS124 circuit!
John Hinson claimed to know the real RS124 circuit. In fact, in
his only post ever on Gearslutz, he claimed that only 3 people have the real schematic. And in addition, one of those people, an unnamed "older gent from abbey rd. studios", got the schematic from Hinson himself. The 3rd person? Unnamed also, but "The other person with the correct schematics will also
not send you a copy." That was in October of 2009 - now that Abbey Road plug-ins have researched the RS124 for their plug-in, there are presumably more than 3 people out there with circuit diagrams from the originals.
Now, given that Hinson has turned out to be a less than trustworthy source, it definitely calls the veracity of his claims into question. He build and sold these RS124 units as the real deal, fetching prices for them that he couldn't have gotten if they didn't have that magical EMI/Beatles aura around them. I'm not saying he didn't build good compressors, but who's to say how authentic his circuit is?
Anyways, I'll wrap this up by saying that the shroud of secrecy around the RS124 circuit rankles my intellectual curiosity. I want to know how they put it together, just for the sake of understanding the thing, and those who refuse to share knowledge that they themselves did not derive really bug me. In other words, if you're an original Abbey Road engineer who designed and built the RS124, and you don't want to share, then fine. But if you're someone who came along and copied their design, yet won't share, then you stink.
Leigh