Discussion in 'McIntosh Audio' started by bryans12v, Jul 7, 2018.
Anyone know what this might be?
Monobloc power amp would be my only guess...…..either that or a widgy gidget….
Thats what I originally thought but went through all the early stuff and didn't see anything like it with this tube compliment.
May have been a one off for in-house use.
"730" could be serial or accounting #. Big tubes were possibly mil/industrial tetrodes or pentodes with button base and one thick index pin and plate out top. Tube layout suggests p/p servo/audio amp.
I believe these units were servo amps that were used in an early computer from the 1950's. The power supply was not supplied by McIntosh and, from what I've gathered, they are not suited for audio. Cool piece of McIntosh history either way.
Variant of the MI200, is the output transformer in the case ?
It would help to see the labeling at the tabs, the main information and what the tabs are labeled.
The only one labeled is the small connector labeled output.
Thanks I was trying to see and have you show to others what the Tabs/ spade connectors said. I see in this photo top left it has some writing as what the connector is?
The full shot of the ceramic sockets is helpful.
Educated guesses, anyone?
I was able to finally locate my notes:
McIntosh Model 640. Tubes: 2 x RK-4D32, 2 x 6SN7 and 1 x 12BH7.
The notes below were on another forum just a few months ago:
MCINTOSH 640 tube type RK-4D32. I had to do some digging and ultimately had to go to Sidney Corderman, VP Eng., to get some info. Those amps were made way back in 1950 for the Eckert Matchley Compan They were servo amps used in computer. I don't remember the output impedances but the amps weren't intended for audio.. The power supply was not provided by McIntosh. The amps probably were used in the ENIAC or UNIVAC computers Frank Gow - Sr. Sales Consultant
Wow - how cool is that!
It doesn't look like anythong on the compendium or any of the literature I have in my files or are stored on my iMac. Maybe one of theguys at Audio Classics might recognize the piece. Ryan you awake?
I had to dive into the mercury based transmission columns that were used to create delay lines for the memory for those old computers.......I can just imagine Sidney and crew whipping out their slipsticks when they were given the challenge of driving piezo stimulators to properly couple, acoustically, with mercury.
I passed on it. It sold for 48 bucks but if it's not suited for audio it would just collect dust here.
Pretty cool piece of history though, I guess.
Off to a collector, no doubt.
"Those amps were made way back in 1950 for the Eckert Matchley Company " MCINTOSH made amplifiers used for computers in 1950 ? Over 25 years before APLE who choose (and paid the right to use) the name of "MAC INTOSH" ?
Life is strange sometime !
Of course "Macintosh" was a ref to the apple type, "McIntosh" to it's namesake co-founder.
Otherwise, fast access memory was a problem for electronic computers in general, recirculating data streams thru delay lines of various types was one approach, but was "volatile" insofar as data was lost when the circulation ceased when power was removed. An Wang's fast access magnetic ring core memory concept did not have this disadvantage and "remembered" data state when powered down, intentionally or otherwise , a significant advance.
Hi Patrice! Indeed. I did get a laugh out of the coincidence.
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