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Author Topic: AKG T 5743 Transformer: Suitable For C12?  (Read 9752 times)

duskb

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AKG T 5743 Transformer: Suitable For C12?
« on: November 23, 2015, 01:10:42 pm »

Klaus,
Can you give me any information on this output trannie? Someone told me this was used in the later model "C12 reissues" but I cant seem to find any information on them doing either a search or asking within the circles i know.

Any idea electrically how they differ from the original T14 or the Hauffe copy?
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Dusk Bennett
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klaus

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Re: AKG T 5743
« Reply #1 on: November 23, 2015, 02:29:28 pm »

T5743 was used in some C12VR and "The Tube" output transformers (labeled "▄66" in its schematics. VR and Tube circuits are identical). I measured a -11dB output, compared to the T14/1 used in original C12 mics. T5743 was also used in the approximately 100 fake C12 made by Norbert Pape in Hamburg in the 1980s.

Regarding Haufe or Hiller T14 transformers:
I have so far not bee able to verify that these were used in early C12. I have just finished authenticating two extremely early C12 from fall 1953 (power supply serial number 001!)and spring 1954 (#017) respectively, and they, just as all other C12 until 1958 I have inspected, were equipped with a Henry Radio V2219 or V2148 transformer. (One exception: Austrian broadcast 'Siemens'-badged C12 had a R÷hde & Schwarz transformer).

Can someone show me a picture of a T14 inside a C12? I have seen Oliver Archut's side-by-side photos of C12 transformers,which included a T14 made by Hiller, but have yet to verify their installation in a mic or their mention on an AKG  schematic. It may be that AKG tried the Hiller in its C1/2 prototypes but during C12 serialization went with the locally-made Henry transformer. Henry also supplied AKG with its C12 power supply transformers.

Proof of the T14 as used by AKG in production mics would help my understanding of AKG's C12 history.
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Klaus Heyne
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duskb

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Re: AKG T 5743
« Reply #2 on: November 23, 2015, 02:56:33 pm »

T5743 is what AKG labels "▄66" as C12VR and "The Tube" output transformers in its schematics (both circuits are identical). I measured them to have a -11dB output, compared to the T14/1 used in original C12 mics. T5743 was also used in the approximately 100 fake C12 made by Norbert Pape in Hamburg in the 1980s.

In this case it's a Pape mic I found it in. Aside from the gain issues, which in theory can be recovered by adding more amplification, how does/would you expect the response or slew rate (if applicable) change between the two? Is it just gain that changes or is there more going on than that?

FWIW, the trannie does not sound bad but compared to any other C12 I believe I hear a difference. It's hard to say if it's any more different than you'd expect to find from one C12 to the next...
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Dusk Bennett
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klaus

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #3 on: November 24, 2015, 02:07:08 am »

It's been a while since I converted a couple of dozen of these Pape copies to C12-functionality for the importer at the time. If I remember correctly, the big 5743 transformer was not bad, but a bit wooley and slugglish sounding, compared to the Haufe T14/1.

Speaking of which: This little guy is one of those magic complements that, on paper should not even work: its core has miniscule iron, it is primitive in its winding structure and blows like a fast blow fuse anytime someone hot plugs a mic. But it's magic in C12, C24, C28 and ELA M 251.

 
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Klaus Heyne
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duskb

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #4 on: November 24, 2015, 03:23:50 pm »

It's been a while since I converted a couple of dozen of these Pape copies to C12-functionality for the importer at the time. If I remember correctly, the big 5743 transformer was not bad, but a bit wooley and slugglish sounding, compared to the Haufe T14/1.

Speaking of which: This little guy is one of those magic complements that, on paper should not even work: its core has miniscule iron, it is primitive in its winding structure and blows like a fast blow fuse anytime someone hot plugs a mic. But it's magic in C12, C24, C28 and ELA M 251.

Thanks Klaus, as always the education you offer is invaluable, really.

In this situation both Jeb (who reached out to you this week) and I are trying to sort through some details on some Pape's you once serviced. I have a Pape (with the 5743) which does sound nice but he's suggesting I make a lateral move over to the one with the T14 since we have the chance. All else being equal the transformers appear to be the only difference (aside from you servicing one and not the other).

We're just going to listen to all of them and I'll make my purchasing decisions on what sounds better. Not jumping ship on a mic that has served me well just because it doesn't have a 'stock' trannie.
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Dusk Bennett
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klaus

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #5 on: November 24, 2015, 04:19:24 pm »

Would it not be easiest to just transplant a T14/1, leave everything else as is, and listen to the same mic? 

I am never comfortable with microphone comparison tests where more than one variable is at play. Comparing two "similar" mics, dozens of variables can overshadow what you are looking for.
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Klaus Heyne
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J.J. Blair

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #6 on: November 24, 2015, 07:20:45 pm »

Klaus, have you listened to any of the current Haufe T-14/1s?  One of my original's wires got so brittle, I was worried about the condition and tried one of the newer Haufes, and didn't hear any noticeable difference.  I wonder if I just had a good batch, or they are actually making a decent transformer. 
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J.J. Blair

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #7 on: November 24, 2015, 07:25:21 pm »

BTW, my Pape mkII has a T5743, as well.  I've always kind of found this mic to sound very useful as is, so I never changed it.  It has the Haun capsule, which sounds much more forward than a CK12, but for some things, it's absolutely amazing. 
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klaus

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #8 on: November 25, 2015, 01:30:44 am »

Klaus, have you listened to any of the current Haufe T-14/1s?

Not recently. I bought mine in the late 1980s. Had them special-ordered from Haufe in the Taunus Mountains. I still remember my conversations with the guy who was in charge: by that time, Haufe made their money with transformers for door bells and similar non-audio applications.

The head guy was very cavalier when I asked him to copy the new ones exactly. I think he said "we never changed anything about them". He also included drawings and a data sheet with the shipment.

So, my longwinded answer: With the late 1980s T14/1 I cannot hear a difference from the 1950s or 1960s, but I may be fooling myself thinking I want to believe that those old amber-colored original T14/1 exclusively made for AKG MUST have sounded better!  But it's such a primitive device, it does not really make sense that some type of sophistication may now be lost...

I would stay away from the ones Telefunken/Northamerica uses. As far as I remember, these have a modified frequency response to compensate for the capsules they were using.
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Klaus Heyne
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klaus

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #9 on: November 25, 2015, 01:32:57 am »

BTW, my Pape mkII has a T5743, as well.  I've always kind of found this mic to sound very useful as is, so I never changed it.  It has the Haun capsule, which sounds much more forward than a CK12, but for some things, it's absolutely amazing.
Pape's  C12 copy mics never came with Haun capsules. He only used Golden Gate CK12 recycled from AKG Service's waste bins.
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Klaus Heyne
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soapfoot

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #10 on: November 25, 2015, 09:14:04 am »

On the topic of duplicating the old transformers exactly, Klaus (and I sure wish Oliver were here to ask, as well)--

Do you perceive that different vendors of magnet wire, and different types of insulation, can impact the performance of a transformer in an audible way? If so, do you have any explanations for why this might be?

I ask only because it is so with guitar pickups-- formvar, plain enamel, polysol all perform and sound differently in that context (though I cannot explain why).
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Jim Williams

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #11 on: November 25, 2015, 11:04:04 am »

Send one to Jensen Transformers and they can model it on their Comtran software. Then every measurement and perameter will be known.

Years ago those in LA would sub a Jensen 1/12 ratio 'direct box' transformer into a C-12 design with good results.
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duskb

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #12 on: November 25, 2015, 01:58:14 pm »

Would it not be easiest to just transplant a T14/1, leave everything else as is, and listen to the same mic? 

I am never comfortable with microphone comparison tests where more than one variable is at play. Comparing two "similar" mics, dozens of variables can overshadow what you are looking for.

Thats a good question because I was wondering the same thing. This guy wants alot of $ over and above what I already have invested in the mic. How much could it possibly cost to swap out a trannie if I was so inclined? PLUS I LIKE the capsule I already have. Lots to wonder about.
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Dusk Bennett
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klaus

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #13 on: November 25, 2015, 05:39:13 pm »

....they can model it on their Comtran software. Then every measurement and parameter will be known.
I am wary of such claims. How is it decided how many parameters, and in what order of relevance, constitutes completion of the exercise? Don't we already have enough mediocre or worse-sounding copy capsules to prove that this approach is barely good enough to satisfy the amateur market? And have we already forgotten the false claims and failed attempts from microphone modeling vendors?

Here is an interesting primer on the immense complexities of audio transformer design:
http://vintagewindings.com/tech%20swag/Audio%20Transformer%20Sound.pdf
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Klaus Heyne
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Jim Williams

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Re: AKG T 5743 Transformer: Suitable For C12?
« Reply #14 on: November 26, 2015, 11:27:37 am »

Jensen has beeen modeling transformers for decades now. The comtran software was developed just for that purpose. I would not dismiss it out of hand. They got a handle on it.

Then again, I do see the value of maintaining some mysticisim about it. That has worked well for other companies over the years.
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