C414, C451/C452 spare parts transformers.

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Bo Hansen

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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 Ü35 is for all these microphone types except C414EB-P48, Ü35 has a ratio slightly less than 1,4: 1 (2,5dB loss with 1,5k secondary termination)
The other Ü54 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 Ü35 and Ü54 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.

--Bo
 
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GeorgeToledo

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Peluso seems to be using a transformer with similar footprint in their EB clone, fwiw.

Contacting AMI, as Klaus suggests on his forum, doesn’t seem like a bad idea.
 

Vac11

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Hi Bo,

are you sure C414EB-P48 U54 transformer has ratio of 6:1?
Someone around changes broken transformer in his C414EB-P48 for Cinemag CM-11021 transformer which has 2:1 ratio. David add there center tap…. Look here:

Best

M.
 

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  • CM-11021 datasheet.pdf
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Bo Hansen

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Hi Vac 11,

I have noticed that there are a lot of misunderstandings with C414EB and C414EB-P48 transformers when this is discussed in various forums.

The Ü35 transformer used in C414E1, C414EB, C451E, C451EB and C452 has less than 2: 1 (about 1,4: 1) in ratio because it has a step-down/loss of about -2,5dB, but Ü54 which is in C414EB-P48 (the first black version where the CK12 nylon/teflon capsule was introduced) has a ratio of about 6: 1 as this has a step-down/loss of about -16dB.

--Bo
 
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gyraf

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Wouldn't it make sense to ask Per Lundahl about this? - magnetic shielding aside, this transformer arcitecture (two bobbins, double-U-core) looks pretty much like the good stuff they usually make.. I'm sure they could be persuaded to skip the shielding and terminalisizing with a bit of pressure..

/Jakob E.
 

Vac11

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Hi Vac 11,

I have noticed that there are a lot of misunderstandings with C414EB and C414EB-P48 transformers when this is discussed in various forums.

The Ü35 transformer used in C414E1, C414EB, C451E, C451EB and C452 has less than 2: 1 (about 1,4: 1) in ratio because it has a step-down/loss of about -2,5dB, but Ü54 which is in C414EB-P48 (the first black version where the CK12 nylon/teflon capsule was introduced) has a ratio of about 6: 1 as this has a step-down/loss of about -16dB.

--Bo
Thanks Bo,
i would be great if you could publish here your measurements to dispel all myths about C414EB and C414EB-P48 transformer.
 

Bo Hansen

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Hi Jakob,

Sure, I have talked to Per Lundahl at an early stage in this matter, also have a sample of their smallest open "flying leads" transformers, but unfortunately something too big in this context.
Unfortunately, the same problem to get hold of the right laminate and bobbin as many other manufacturers I have talked to.

It is necessary to make these transformers in exactly the right size, there is no room for any larger one.
On the C414 there is even an extra cut out in the bottom of the frame for the bobbin to fit, and in the "pen microphones" C451 / 452 it is an absolute must to have the right size otherwise the outer tube can not be put on.

--Bo
 

Bo Hansen

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Peluso seems to be using a transformer with similar footprint in their EB clone, fwiw.

Contacting AMI, as Klaus suggests on his forum, doesn’t seem like a bad idea.
Hi George,

Thanks for the tip, I did not know that Peluso made his own version of the C414EB.
But when I look at their pictures on the inside, it seems that their transformer is larger and is also mounted in a completely different way.

Since I see on their website that they sell a lot of the most common old microphone output transformers (maybe China made ?) I have emailed them and asked even about the type I am looking for, we will see what they answer.

--Bo
 

GeorgeToledo

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Hi George,

Thanks for the tip, I did not know that Peluso made his own version of the C414EB.
But when I look at their pictures on the inside, it seems that their transformer is larger and is also mounted in a completely different way.

Since I see on their website that they sell a lot of the most common old microphone output transformers (maybe China made ?) I have emailed them and asked even about the type I am looking for, we will see what they answer.

--Bo
Thanks for that detail Bo, I hadn’t compared side by side.
 

mylesgm

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Not needing a transformer for a C414eb but needing a pattern selector switch as one of mine is missing both the bearing that allows the switch to "stop" at each pattern but also the tip of the switch has broken off requiring a pen to change the position. Any source for replacements?
 

Bo Hansen

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would not be possible to maybe just re wind it?
12afael,

Maybe I have not really explained why I am in need of these transformers, but this is the situation.....
It is not one of my own C414 that has broken, and I will not DIY build any.
I repair and renovate lots of C414EB, P48, C451 and C452 microphones for customers here in Sweden, and since it happens quite often that a transformer is broken, I must have these in stock for direct access.

--Bo
 
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Moby

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Have you talked to Moby?
Hey, few members asked me about U54, U35 and also U11 possibility, but laminations size and bobbins are non standard. It will be not for the first time that I make special tools but we never reached minimum needed quantity :(
 

doqmemory

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Not needing a transformer for a C414eb but needing a pattern selector switch as one of mine is missing both the bearing that allows the switch to "stop" at each pattern but also the tip of the switch has broken off requiring a pen to change the position. Any source for replacements?
I ordered replacement switches for my C414EB P48 directly from Harman (now owned by Samsung, apparently). I found the part number from a pdf of the user manual, then got the phone number to the Harman parts department from a web search. I think the email address was:
hpropartsusa@harman.com

It was about $25 total, but YMMV. Older parts are getting rare, but you might luck out.

Another option for those switches is to pull one off an old AKG dynamic microphone. The D330BT uses some of the same custom switches.

--Mike
 

Moby

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Tanks JerryPbury, and Moby because you stuck in so fast.

Moby can I reach you via PM or your email ?

--Bo
Hey, no problem. Write at mobyelectronics at gmail dot com
 

mrgrooves666

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I just placed an order for one of the three position selector switches (high pass filter) for one of my pair of c414 BULS to Full Compass, and 2 of the CK12 C12VR capsules to replace them fresh. They didn't have any in stock currently, but supposedly they were recieving during this month.
And here's the part you're looking for:

Order now before who knows what happen to AKG..
 

muffy1975

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U54 TX : -

I asked Peluso which TX they use in their own 414 and he told be they use the T14. Can that be right? the T14 is 12:1.

I am trying to find a U54 TX. Bo mentions above that the U54 should be 6:1. Does that mean, if space was no issue, the Bv8 style TX would work in this circuit? I believe this is 6:1.
 
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