Sunset sound demedio api

[pucho812]

Anyone have any info on the 312 demedio mods?

I found this
http://m.ebay.com/itm/140592873802?cmd=VIDESC

And a repost of txt in case the link does.


Here's something rare.
Vintage API 312 microphone preamplifier circuit built from Sunset Sound 325 card.
This mic preamp is setup to fit any API 500 series lunchbox
A rare vintage mic pre: the studio standard for excellence around the world.
The original 325 card was pulled from an API Demedio console that used to be in Sunset Sound Studio 2.
This 325 card has been made into a mic pre based on the API 312 circuit and the Sunset Sound revision of the circuit.
These cards feature the Sunset Sound and Jensen improvements to the API 325 card.
The Deane Jensen designed 990 opamp was patented (US Patent 4287479) and served as the basis for the amplifier.
The pairing of the 990 with a Jensen JE 123-AL nickel alloy output transformer gives a clear present tone that is magical on vocals.
The opamp and input transformer pairing was designed by Deane Jensen as the ideal combination for a mic preamplifier
The low turns ratio input transformer will have lower distortion, wider bandwidth and improved phase response.
The phase accuracy is also improved by the jensen output load isolator (JOLI: the red coil) which improves the phase response at the output transformer.
Adding the low turn ratio JT 16 input transformer makes these identical to the mic pres in the Demedio boards at Sunset Sound and Paisley Park .
Prince'ses first records, Van Halen'ses first records, even some Led Zeppelin tracks we're cut using mic pres of this design.
This very 325 card spent over a decade at Sunset Sound working on those very records.
I've recapped and rebuilt this card to function problem free for another 40 years.
Minimal noise and crystal clear output power; sounds amazing on vocals and guitars.
Fully setup and ready to amplify signal in your studio. Whatever you put in comes out sounding like a record.
The module is set up with a 25K reverse log gain pot, Phase, 20 dB pad and 48 volt phantom power.
The original card, vintage opamp and transformer have been preserved; no traces have been cut, no holes drilled into the card.


So looks like they used a 900 vs a 2520 and Jensen transformers. Can anyone confirm this?

 

[jensenmann]

All that sounds basically like the 990 application note from here: http://www.johnhardyco.com/pdf/990.pdf

 

[ruairioflaherty]

Exactly.  Once you put a 990 in there it's going to be best matched with a 1:2 input transformer ratio.  Once you've added an input and output transformer and a 990 there isn't much left of the API...

 

[keefaz]

The phase accuracy is also improved by the jensen output load isolator (JOLI: the red coil) which improves the phase response at the output transformer.

Prevents oscillation and instability in line driving op-amps
No effect on audio frequency response or transient performance

http://www.jensen-transformers.com/datashts/oli3.pdf

 

[deveng]

Pucho,

I found this auction on Ebay as well and was interested since I was a tech at Sunset Sound and sister studio Sound Factory and worked on those consoles.  There are some truths to the auction statements but the accuracy of some statements is not all fact.  Yes, Sunset Sound did replace a lot of 2520's with Jensen 990's.  They also used the 123 transformers.  But as I remember the inputs were JE115K's.  I don't remember seeing load isolators on the 312 cards but there could have been some on a number of them (not all though).  The statement that this 325 card was in use in the Studio 2 for years is a bit misleading.  312 cards were used as 312's and 325's were used as 325's.  The 325's were not modified to work as mic pres.  This applies to the Sound Factory API's as well.  It important to note that I'm now talking about the Studio 2 and 3 DeMedios as the Studio 1 console is totally custom and is a bit different!  When using the 990 opamps on the 312's and if the Jensen input transformers were added, the termination network was changed as well as the feedback capacitor value (polystyrenes when re-worked) around the 990. 

The Sound Factory consoles are both completely modified API's.  Custom pcb's but still use the 2520/2503 and 2520/2603 combinations.  These consoles are a whole other story.  Great consoles by the way!

Both the Sunset Sound and The Sound Factory did not take modifications lightly and did so only after considerable discussion.  Mods were not made purely for technical reasons.  Great engineers were consulted and listening tests were done before making changes.  Both facilities have always had very talented engineers and maintenance staffs!

So, take the auction text with a grain of salt.  Its based on some real truths but is a bit misleading on the nature of these particular cards.  As I remember there was never a card used at Sunset Sound or the Factory that existed in the form that these cards present.

 

[pucho812]

That was awesome. thanks for the details. I knew someone around here would actually have been close to the source and be able to confirm or dispute the details. I'm not looking to pick it up or any of that kind of action, was just curious if the information was true...

 

[deveng]

I'm looking back on those consoles and there were hundreds of 312's within those consoles!  Since most of them just plain worked for years without any need for maintenance, even over the years I worked there, some I never pulled from the consoles.  So, there could have been versions of the 312's that I didn't see.  But from what I remember they were very consistent.  I was there when that console was pulled from Studio 2 and replaced with an Amek (which is now also gone).  I didn't know where it (the DeMedio) went after that. 

Those API's sound awesome.  The original Sound Factory Studio A console channels were difficult to work on (old delicate wiring and multi-level boards).  Not so after we rebuilt them (both the S.F. consoles were modified and are still in use today).  The DeMideo's in Sunset 2 & 3 worked most of time I was there and required little maintenance.  Every once in a long while, a 2520 would go, but other than that not much went wrong.  Reliabililty was even better with the custom in Studio 1. 

 

[pucho812]

The sunset sound Amek was available for sale not to long ago. I don't think it ever got sold but it was in craigslist for a moment.