BV8 Dimensions - Can anyone help?

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Buttercup

Well-known member
Joined
Jun 8, 2004
Messages
122
Location
Devon, England.
Hi

Does anyone have any dimensions ( stack height, bobbin width etc.... ) of a real BV8?
There is a laser cutting machine poised over some aluminium disks at the moment - waiting for direction.........
I would like to try a Cinemag but I fancied having a go at my own too and
I may be prepared to do a run if I am successful :wink:

Huge thanks

Giles
 
you dont wanna use aluminium for the lams, do you? :)

the lam type is called UI30/25, the core, when put together, is 30x35mm, stack height 12mm.
bobbin is 22mm x 20mm x 15mm each (so both 40mm wide when put together)

some pics of my clone (original lamination, selfmade bobbin)
http://www.twin-x.com/groupdiy/thumbnails.php?album=271

i´m still searching for laminations with the same qualities as the old stuff...

-max
 
Hi Max

Thanks!
Your transformer looks fabulous!

Aluminium for the lams?
Hmmm...I was actually going to experiment with the magnetic proerties of balsa wood - to make a really light mic!

I dont have the machinery to make bobbins so I found a company who wil do it for me and a local sheet metalwork company who will cut the UI30 ( 30X40 ) lams I have down to the right size.

Oliver has said that some early BV8's were not multi chambered so I might try this for simplicity ( and cost cutting ).
How does it affect the sound or does it not really matter significantly?

Giles
 
hi giles,

balsa has very nice magnetic characteristics, nearly as distortion-free as air :wink:

i wanted to go all original with my bv8, the bobbins are milled pieces, key and slot joint, glued together, lots of work...

if you want bobbins without sections i can send you some - they are readily available (ei30/12,5)
you can cut the sections and glue them in, thats what i did before i had my own bobbins made.

i realized that oliver uses one chamber only - there is some difference but its ok.

cutting ui30 might work (which alloy?) but the 4 holes at the edges instead of the two will also make some difference with the eddy currents etc.
i also have some ui30 permalloy, but i prefer to use it as is - cutting it down is for cosmetic reasons only.

experimenting is the way to go with transformers, having a original doesnt harm.

best regards,
-max
 
Hi Max!

That's really kind of you!
I'll pm my address over to you.
Interesting about the eddy currents - I can see that I need to learn lots more about this and I can't wait to get experimenting!
This and the DIY anamorphic Cine lenses I'm messing around with at the moment........
Just not enough hours in the day :grin:

Best regards

Giles
 
This is a very old post but if anyone is interested you can get Clone Neumann lams and bobbins from here
https://groupdiy.com/index.php?topic=66764.msg846268#msg846268
 
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