June 21, 2013

Hit That Perfect Beat, Boy...

by Chris Randall
 

Analog Beatz. #RT60

As anyone that follows me on Twitter knows, I'm currently in Hood River, Oregon at my family reunion. I spent a chunk of time earlier in the week at J-Hi's studio recording the rhythm parts for what will be the next RT60 release (which, as it happens, will be a double A-side 7" only, no digital. Sue me.)

While there, I became a convert vis-a-vis the SEM module. While I appreciate the power of Oberheim synths, their general sound has never done anything for me. I had not, however, ever used a real SEM. The original one in the picture above (run via CV/Gate outs from the A4) changed my mind in a hurry. I don't know how close the new ones sound to this vintage one, but jesus fuck, what a cool sounding synth. I think I'd need to do a side-by-each comparison, but I may break my moratorium on GAS if the new ones are even in the ballpark.

Speaking of GAS-moratorium-breaking, I recently got a Craigslist score in the form of a like-new DK Synergy II+ with all the Wendy Carlos cartridges, which will get a video and "review" as soon as I get back. Suffice it to say, mind: blown by this thing. I've been trying to coax an emulated Kaypro II in to being able to program it, and I feel I'm not far from success in that regard, but honestly, there are only so many hours I can dedicate to that task that would be better spent doing, you know, my job and stuff.

Anyhow, that's it for now from the Great White North(west). Back to our favorite family sport, trying to belittle each other to the point of tears.
 
 
 

42 comments:

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Jun.25.2013 @ 7:15 AM
silent5
What is the round metal thing on the front of this SEM?
 
 

 
Jun.25.2013 @ 8:30 AM
DGillespie
What Adam said.

Also, a big difference is that many of the active components (transistors and op- amps) may not be available anymore. Or if they are, they'll be made by a different process and have slightly different specs.

Layout can make a difference, but at these frequencies I'd be very surprised if that was the difference you'd be hearing. It's probably slightly different parts and and component tolerances, if anything.
 
 

 
Jun.25.2013 @ 9:00 AM
Chris Randall
@silent5: It is a mic stand mount. No idea why it is there.

-CR
 
 

 
Jun.25.2013 @ 9:14 AM
Adam Schabtach
What @DGillespie said.

I just googled up the schematics for the original SEM. There is a pair of CA3080 OTAs in the filter, and one in the VCA. Those chips are no longer made. There are a few left here and there, but I doubt Mr. Oberheim would design a new product based on the tenuous availability of NOS parts. They've probably been replaced with LM137000s. I'm sure that there are threads out there in which the pros and cons of each are hotly debated; bottom line is that the new SEM doesn't have exactly the same parts as the old one, and hence can be expected to not sound exactly the same, even neglecting the variation between old units as described previously.

And yes, stray capacitances etc. from layout generally come into play only in the megahertz range of frequencies. You can't hear their effects. Honest.

In the end, though, who cares? We all know that rational analyses have little to do with synthesizer purchases.

--Adam
 
 

 
Jun.25.2013 @ 9:23 AM
silent5
@CR: I see. I can only assume someone put it there as opposed to the bottom so they could still place it flat on a desktop? Looks a bit like an R2D2 interface.
 
 

 
Jun.25.2013 @ 9:44 AM
Chris Randall
I don't speak Drum, but in looking at it I think it's actually a header (?) for one of those doo-hickies you stick a tom to on a drum rack. This particular SEM has a noise source added internally (that's what that switch turns on and off) and I believe it was used as a synth-drum for the most part. That would explain the placement.

-CR
 
 

 
Jun.25.2013 @ 5:24 PM
Scodiddly
If that's not an Atlas AD-11 mic stand flange adapter then I'll be dipped in the anti-flea medicine of your choice. But then somehow 5/8"-27tpi is the American standard for microphone stands, and gets into all sorts of odd places.
 
 

 
Jun.25.2013 @ 5:43 PM
Chris Randall
Fuck if I know. It's gone now. First thing my tech took off in his quest to return this thing to its former glory.

-CR
 
 

 
Jun.25.2013 @ 7:24 PM
seancostello
@Adam: Apparently the OTA in the LM13600/13700 is identical to the 3080:

link [www.idea2ic.com]
 
 

 
Jun.25.2013 @ 9:05 PM
Adam Schabtach
@sean Hah! Interesting. I stand corrected. Good to know--thanks.

--Adam
 
 

 
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