Sphere Goodies SAVED from the Dump !!

[gar381]

compairing the SPA-62 card (The little mini DOA) to the 17363 card DOA
the circuit is the same except for:

The SPA-62 card uses 2N2219/2N2905 output transistors
the 17636 card uses   2N4238/2N4235 output transistors

one of the transistors in the 17636 card is changed from a 2N2484
to a 2N3904 on the SPA-62 card.

Biasing diodes are bypassed with resistors in the SPA-62
and not in the 17636

Coupling caps in the SPA-62 are Tants
Coupling caps in th 17636 are Alum Electros

BTW.. 2.2uf/35v tants are on the rails of both cards
however the ones on the 17636 cards were added/modified
after thoughts.

GARY

 

[hitchhiker]

I have a 12 x 4 Sphere remnant that uses the later spa-62 with bulbs that alight when they go bad.

This version of the little spa-62 has 2N2219A &  2N2905A output T's

Q1 & Q2 are 2N2484, Q3 is 2N5087,  Q4 is 2N3904

I'll upload the 2 part scheme that matches the version to the the diylab account.

Could you measure etc the output transformers, my console was stripped of all input and output transformers as well as the input cards.

Lance

 

[gar381]

Hey Lance  Thanks for the schizz.  Counting your schizz and my reverses
I have found 4 variations !!  Some with input protection diodes some without
Some with on board output cap some without.  Lots of variations of
resistor values.  One with bypass resistors around the bias diodes.  WOW
lots to play with.

The 7393 transformer has 4 windings like a ap2503.  They are wired 2 in series for the
pri. and 2 in series for the sec.  Setup 1:1 ... probably 600:600.  I had a chance to listen
This Trafo sounds VERY NICE.  Reminds me of a cinemag CMOQ 2S.

Hope this helps Lance.

GARY

 

[hitchhiker]

thanks Gary, that's good to know.

The output cards on my little mixer use modified 900 eq circuit boards that have 2 discrete SPA-62 opamps.
One being the fader buffer and the other the line output amp. The only difference in the summing, fader and output opamps is the gain set feedback resistors and cap values. And IIRC the output caps vary too.

I'm thinking of making up input cards containing fader buffer and a pan buffer/output to bus DOA style.
Maybe some channels with 1731 and some with 2520. I've never drawn up my own pcb before and so this will be quite the learning curve for me. Also have to find affordable input transformers.

Lance

 

[peterc]

Uploaded all my Sphere stuff to the gmail account, hope it helps

Peter

 

[gar381]

Good stuff Peter!!

Thank you my friend.

GARY

 

[gar381]

Hey Lance..

I just got an email from David Geren at cinemag about these transformers:

"The 7393 was also made by Reichenbach Engineering as the JE-123-SL and the RE-123-SL.  Jensen should have the data sheet on their web site.  Our part number is the CMOQ-3x (suffix "H", "L", or "S" representing the different core choices).  The 7393 (as are the Jensen parts to this day) was made with a 50% nickel alloy core.

The 76113 was also issued as the JE-11-B and is 10K:10K.  It does not have a Faraday shield and the winding structure is very simple. We do not make it anymore.  It is a bifilar transformer."

Great info !!

Here is a link to the JE-123-SL:

http://www.jensen-transformers.com/datashts/123slcf.pdf

GARY

 

[hitchhiker]

awesome! thanks Gary.

I guess cinemag only offer 600/600 line inputs unless it is a special order.

or maybe Cinemag CMLI-15/15B2 is a good choice ?
http://www.cinemag.biz/line_input/CMLI-15-15B.pdf

Lance

 

[gar381]

Lance

http://www.jensen-transformers.com/datashts/11p1.pdf

The modern day JE-11-B and is 10K:10K

The CMLI-15/15B is a great trafo but the JE-11P-1 is probably more Sphere like.

Gary

 

[hitchhiker]

Gary

I only see 2 of the 76113 in your pics. Are you considering a 12 ch line mixer?
Have you tried a mic pre or line level test to hear the spa-62 sound yet?

Lance