R/E/P > Klaus Heyne's Mic Lab

AKG C414, C451/452 spare parts transformers

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Bo HansÚn:
Hallo microphone tech friends.

I have been thinking for a long time about how to solve a problem getting spare parts transformers for some older AKG microphones.
These transformers are for C414E1, C414EB, C414EB-P48, C451E, C451EB, C452.
All have the same physical size, as well primary impedance and ratio except for C414EB-P48 which has a much higher primary impedance and ratio.

I have had about 10 of each type in stock for the past 15 years, but now they are out of stock, as I have repaired lots of these AKG C414 and C451/452 types over the years.
They seem to break for two reasons, partly because the phantom feed to microphone electronics are driven by the secondary CT/center tap and partly because many of them are mechanically fragile as the bobbin wire is only protected by wax.

Transformer type ▄35 is for all these microphone types except C414EB-P48, ▄35 has a ratio slightly less than 1,4: 1 (2,5dB loss with 1,5k secondary termination)
The other ▄54 for C414EB-P48 has a ratio of 6: 1 (16dB loss with 1,5k secondary. termination.)
But I will check the impedance and ratio measurements again so I am sure it is correct exactly on the dot.
The laminate/core and the bobbin must keep their exact dimensions, there is absolutely no space in reserve in any of the microphone types.

I have among others talked to David Geren at Cinemag, but their smallest microphone output transformer types is unfortunately too big, and at the moment they can not make any smaller size because they do not have the right laminate and bobbins.
Of course I have also talked to Lundahl here in Sweden, but they also have problems with this laminate and bobbin size.
I have not given up Cinemag and Lundahl yet because both makes great transformers.

Since there are many of you microphone repairers and builders hanging out here on this forum, I thought I would ask if any of you know anyone who manufactures these two types as directly suitable replacement transformers.
I've noticed that there are a lot of China made replacement transformers for our old Neuman, AKG and Telefunken tube microphones and some other solid state types sold on many DIY web sites, but I've never seen anyone make these AKGs ▄35 and ▄54 types.
I think there must be more of you who have problems with this type of broken transformers and have a hard time getting them as a spare part.
My idea is to let someone manufacture these two types with good quality, partly for my own needs but also for others with the same problem.


Check with Dennis Maximova, head of TAB Funkenwerk/Atelier Magnetics in Washington State (sales@tab-funkenwerk.com).

Let him know you found the info on my forum. That may help.

Bo HansÚn:
Thanks Klaus, yes I will do so.


Another possible source that does custom transformers is Cinemag.

Jim Williams:
Jensen has developed some mic transformers. They have excellent Swiss winding machines and the expertise. Contact Dave Hill.


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