MA1 GERMANIUM mic pre support thread

[bruce0]

Low priority question.  Anybody know what color blue is the blue text on the front panel that says "MA1 discrete mic/di ..."

A pantone color or something, or a name of the ink/paint?  Or a company where the panels were made where I can check.  I want to make the knob (or at least the insert) match the color (I know... a little anal, but just want to make it look good.

It is sort of an odd light purplish blue, and nice looking, if the knob insert matched it would click.

 

[manulaudic]

Bruce0, Thanks a lot for posting pictures of your build it looks very easy indeed!
I have been so busy making a record i haven't had time to source the transformers... I was going for Classic api but now i see yours. they look Great and you mention that extra vintage dirt which i am after !

What are the exact transformers used? Can i source them somewhere? I found these on ebay :http://www.ebay.com/itm/2-Beyer-Dynamic-Input-Transformers-MC-Step-Up-Tube-Mic-Preamp-/121317108922?pt=Vintage_Electronics_R2&hash=item1c3f102cba

Thanks again,
Manu

 

[bruce0]

They are old salvaged steel core transfomers I found in some old ESPN battery powered, transformer coupled 5534 mic amps (used for driving long lines on remote shoots).

But the equivalent are available.

Classic API's would be a good choice, I just wanted to build mine with what I had in the shop (I had everything but the germanium and the pot (classic api).

If you want a dirtier transformer, probably go edcor.  They should have something that will fit.

Biggest problem with mine is that it was the wrong SIZE.

For less precise sound (color?) choose one of the EDCor steel transformers of the correct dimensions.  You have to wire it 1:2 or 2:1 I forget, but any quad filar trafo would probably do.  Just make the dimensions match the classicapi one.

Or use the classicapi one.

I have not listened yet (I order knobs and pots, but forgot to put the pots in the cart.  So I am still waiting to finish them.

 

[bruce0]

Finished the build. 

Checkout was showing some response "oddities" so I swapped in a Jensen 110K transformer to try to fix it, which didn't help.  But then I realized my test cable was broken, and  all is well.  So they are up and running with flat response.  Pretty little things too.

 

[okgb]

Yeah, I'm a fan. Thanks Pier

 

[ppa]

thank to you and to who has believed in this my gear, even if you known that it was a new one.

 

[Potato Cakes]

Pier, as I anxiously await my kits to show up, I was wondering if there was anyway to internally add a trim pot to lower the output level, making it  possible to drive the germanium circuitry harder without clipping the inputs of an A/D converter? There's not really any space on the faceplate to add a second potentiometer for this task, hence the inquiry regarding doing this internally. If it was possible, is there a particular place in the audio path that this would work best? Thanks!

Paul

 

[ppa]

Pier, as I anxiously await my kits to show up, I was wondering if there was anyway to internally add a trim pot to lower the output level, making it  possible to drive the germanium circuitry harder without clipping the inputs of an A/D converter? There's not really any space on the faceplate to add a second potentiometer for this task, hence the inquiry regarding doing this internally. If it was possible, is there a particular place in the audio path that this would work best? Thanks!

Paul

Hi Paul,

as used by other menbers here, as I have suggested them, is possible using the  attenuator
that Jeff Steiger sells here http://classicapi.com/catalog/product_info.php?cPath=48&products_id=256
Forum menbers generally put them on the MA1's DI hole.
This attenuator should be used between the out of the out transformer and the out of MA1 as for CAPI pres
If you would not like it I could suggest you other solutions.

thanks
best regards
Pier Paolo

 

[Potato Cakes]

Fantastic!

Can't wait to get these guys built!

 

[Potato Cakes]

For everybody who has already built one of these guys, what are transformer options you have tried and really liked? Right now I'm thinking about using Lundahl or Cinemag for the input and Cinemag or EA for the output. Thoughts?

 

[ppa]

For everybody who has already built one of these guys, what are transformer options you have tried and really liked? Right now I'm thinking about using Lundahl or Cinemag for the input and Cinemag or EA for the output. Thoughts?

just my thought,

in any case they sound great with MA1, you have adduced all transformers I like.

I like very much Lundahl transformers, Lundahl is knowed to be a bit cold, but with germanium color they make a very fine synergy. As output EA should be better with it.

The alternative  is all cinemag transformer.

Pier Paolo

 

[Potato Cakes]

Pier,

Do you know of any of the Lundahl input transformers that will directly fit to the PCB?

Thanks,

Paul

 

[ppa]

Pier,

Do you know of any of the Lundahl input transformers that will directly fit to the PCB?

Thanks,

Paul

Hi Paul,

thanks for the question, Lundahl are transformers I like very much.
The Ma1's footprint is also for the following Lundahl transformers:


– LUNDHAL LL1538
– LUNDHAL LL1538XL
– LUNDHAL LL1576
– LUNDHAL LL1578
– LUNDHAL LL1576XL
– LUNDHAL LL1578XL

I council you the LL1576

Pier Paolo

 

[ppa]

Pier,

Do you know of any of the Lundahl input transformers that will directly fit to the PCB?

Thanks,

Paul

there are the holes where soldering these lundhal transformers

inside  green rectangle there are the holes for primaries and on yellow for the secondary.

it's important to avoid shortcuts that the transformer's bottom, that's conductive being mumetal, touchs the footprint's holes

 

[ppa]

this is the holes for haufe st8456

on blue the holes for primaries and green for secondary

 

[ppa]

here the holes for sowter

on blue the holes for primaries and green for secondary

 

[Potato Cakes]

Crap! Now I have to buy more to try out all the transformers!

Thanks for info!

 

[KMB-AUDIO]

PPA, are the silkscreen color designations on the PCB supposed to match the EA 2503 output transformer? Looking at the schematic and the data sheet for the EA (http://www.classicapi.com/catalog/images/gallery/2503/2503-specs.pdf), they dont seem to match up. Just want to make sure I'm not seeing things before I hook it up.

 

[ppa]

PPA, are the silkscreen color designations on the PCB supposed to match the EA 2503 output transformer? Looking at the schematic and the data sheet for the EA (http://www.classicapi.com/catalog/images/gallery/2503/2503-specs.pdf), they dont seem to match up. Just want to make sure I'm not seeing things before I hook it up.

don't worry Matthew, they're correct  8)

Pier Paolo

 

[KMB-AUDIO]

Ahh, I see what you did there. A bit unconventional, no?