API 553 PCB

[Fablab]

Hi Kevin, thank you for the photos.
Unfortunately the PCB of your module is the original API that has some little differences in the traces from the Datatronix PCB posted by Gary

 

[gar381]

Looks like there is a slight difference in the original and datatronix layouts .
When I get mine out of the rack I'll get some tight shots of this area.

GARY

 

[Strawtles]

Great Gary, some photos of your Datatronix module may help a lot

 

[gar381]

Here is one of my Datatronix Modules with the DOA removed
so you can see the traces thru the PCB.

The markings for R13 and R14Make no sense to Jeff's Skitz.
These 2 Rs are un-need anyway so I just ignored them

Looking at what I did to make these guys work... note the 2 Jumpers.
This puts the PCB in sync with Jeff's Skitz (except R13 & R14)

Hope this helps!

 

[Fablab]

This help a lot Gary !!

As I need to have a balanced input and unbalanced output, do you think it is possible to use this eq without the output transformer with a 10k:10k transformer for balancing the input?

Merry Christmas to all!
Fab

 

[gar381]

This help a lot Gary !!

As I need to have a balanced input and unbalanced output, do you think it is possible to use this eq without the output transformer with a 10k:10k transformer for balancing the input?

Merry Christmas to all!
Fab

You can use your input trafo  and keep the output trafo but run it unbalanced.

GARY

 

[Strawtles]

Hi Gary,
is it possible to use a 1:1 output transformer instead the original 1:3 one?

 

[Walrus]

Just wire it so you only use one winding.

 

[Strawtles]

Kevin, my question is if I can put on these module a 1:1 transformer intead of the original one that is 1:3
and what happens using a different ratio 
Happy Christmas

 

[gar381]

1:1 vs 1:3.. 

With 1:1 You lose just a bit south of 10db of gain vs 1:3

It will work But stock 553s use 1:3 on the output.

GARY

 

[Fablab]

Gary,  when you say to run the output trafo unbalanced you intend joining the negative of transformer with the ground?

 

[gar381]

Don't unbalance on the module pcb.  Unbalance it in your external cabling from your 500 series rack.

GARY

 

[Strawtles]

Great Project!
anyone knows where I can find some 2520 PCBs in Europe?

 

[gar381]

http://classicapi.com/catalog/index.php?cPath=71_72

Jeff ships worldwide.

GARY

 

[Strawtles]

Thank you Gary
Do you know if there is a 2520 type opamp that can be used without transformer?
I am considering to use a couple of these modules in a portable channel strip

 

[gar381]

You don't need a transformer for any of them.  Just use at least a  470uf/16v cap on the output of each DOA but  do
use a trafo to get that IRON MOJO    Transformers are your friend !!

GARY

 

[Strawtles]

 

[Strawtles]

Gary, do you know if there is a 2520 type opamp that works with  +28/-28 Volt?
Happy new year to all!

 

[acquisitions]

Does anyone know what the dimensions of the board are?  Looks like it may be different than the standard 500 series spec dimensions I can find?  Thanks!