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Author Topic: Can you hear the transformer in some of these mics?  (Read 19115 times)

Mike Jasper

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Can you hear the transformer in some of these mics?
« on: June 13, 2009, 11:00:55 AM »

The short answer is... I doubt it.

I've posted a link to seven mics, all recording the same acoustic guitar into the same mic pre/converter chain.

Which mics have a transformer? I guarantee you at least one of them does.

If you want to listen, you'll have to PM me for the link. I also won't post the answers here, but I will provide you with all the answers once you've guessed (and believe me, it's a guess).

Also, your answers won't be shared with anyone else. Here's the way I see it -- if I can't tell if a mic has a transformer just by listening to it, then why should you be able to?

Jasper
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Barry Hufker

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Re: Can you hear the transformer in some of these mics?
« Reply #1 on: June 13, 2009, 12:40:27 PM »

You are supposed to PM for the link.  Please read carefully all rules before playing this game.

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Oliver Archut

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Re: Can you hear the transformer in some of these mics?
« Reply #2 on: June 13, 2009, 12:57:30 PM »

Hello Mike,

maybe I am missing the point, but every test is only as good as it is executed. Hearing x-former in links on the Internet? I doubt it too.

But here are some test that I did over the years,

Transplanting all Fender Bassmann x-former to a Marshall JMP and vice versa, the sound follows the transformers meaning the Bassman sounded like a Marshall.

Transplanting a BV11 (M49 x-former) with the needed mods into an U47 and the U47 starts sounding pretty similar to a M49. Headroom did not change however.

In a test reducing the winding as well the core material in quality, at one point the x-former started to sound just by being in the chain.

Point of x-former is not to hear it, if it is good designed you are not suppose to here it. But in some setups you can trigger it to hear it.

Best regards,

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Schallfeldnebel

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Re: Can you hear the transformer in some of these mics?
« Reply #3 on: June 13, 2009, 12:58:52 PM »

You can off course also do a test with an instrument having a little bit larger bandwidth than a guitar. With e.g. pipe organ I can assure you a trained listener can tell when there is a transformer in the chain.

In your case, it is not a real ABX test. If you would ask me to hear the difference between a standard Neumann KM84, and one modified without transformer, you can wake me up in the middle of the night, and I tell you in an A-B comparison which is which.

This pre you use, does that already have a transformer inside? If so, it makes it more difficult to hear the character of a transformer inside a microphone.

There are bad transformers, there are good transformers. Bad ones will be more easy to detect. Take a DPA 4006 and a DPA 4006TL. Many claimed to hear a huge difference.

SFN
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MDM,

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Re: Can you hear the transformer in some of these mics?
« Reply #4 on: June 13, 2009, 06:30:58 PM »

the transformer defines the amplifier... usually.

if there is no transformer, that means that there has to be a line driver built into the mic with at least a few transistors, and in the worst cases an op-amp or other IC circuit.

if you can't hear the difference between a transformer output and a solid state transformerless something is going wrong, IMO.
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Mike Cleaver

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Re: Can you hear the transformer in some of these mics?
« Reply #5 on: June 13, 2009, 10:21:53 PM »

Ditto.
Listen to the classic Neumann mics WITH transformers and the newer TLM (transformerless) models.
None has what Klaus calls the "sex appeal" of the originals.
Examples, TLM 49 and TLM 67.
There is no comparison.
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Schallfeldnebel

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Re: Can you hear the transformer in some of these mics?
« Reply #6 on: June 14, 2009, 06:49:29 AM »

In the past transformers were used for what they were designed for, impedance matching and galvanic seperation. Nowadays the transformer has become a part of the colour palette of recording art.

A transformer can work as much against you as it can help you making a voice sound with sexappeal. If you record music in natural reverberant rooms, main microphone set-ups with transformers can cause you sleepless nights, because of uncontrolled bass behaviour.

I still prefer a Neumann U77 (the first Neumann transformerless microphone from the 70s) over any U87 or U87A.

I rather work with a complete transformerless set-ups, and when I need the specific sound of good transformers,  I insert a transformer in the chain.

SFN
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Mike Jasper

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Re: Can you hear the transformer in some of these mics?
« Reply #7 on: June 14, 2009, 12:53:32 PM »

I came up with this transformer test after a couple of guys told me, "Of course the mic has a transformer. Can't you hear it?"

I couldn't. And the mic was the Mercenary KM-69.

Jasper
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Eric H.

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Re: Can you hear the transformer in some of these mics?
« Reply #8 on: June 14, 2009, 01:18:10 PM »

Schallfeldnebel wrote on Sun, 14 June 2009 11:49


If you record music in natural reverberant rooms, main microphone set-ups with transformers can cause you sleepless nights, because of uncontrolled bass behaviour.


Could you elaborate on this?
Could it be because of a bad combination of impedances between the mic and mic pre?
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J.J. Blair

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Re: Can you hear the transformer in some of these mics?
« Reply #9 on: June 14, 2009, 02:39:48 PM »

Schallfeldnebel wrote on Sun, 14 June 2009 03:49

I still prefer a Neumann U77 (the first Neumann transformerless microphone from the 70s) over any U87 or U87A.


Well, first off, that's not a terribly good transformer.  Secondly, perhaps what you are hearing is the poor implementation of a FET, and all sorts of NFB filters.  Would you prefer a U77 to say a Klaus'd U87, with one of Oli's transformers?  That's the real question.
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Schallfeldnebel

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Re: Can you hear the transformer in some of these mics?
« Reply #10 on: June 14, 2009, 02:40:19 PM »

Although unmeasurable with static signals, transformers add extra bottom to the low end, approx. around the 60-120Hz area. Often the same bandwidth as disturbing resonances in halls and smaller churches. Together they can add up and cause a muddy bassresponse.

The opposite, when a recording has too less bottom, using a main pair with transformers, or using transformers in the signal chain, can help you to get the sound you were looking for.


SFN





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Schallfeldnebel

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Re: Can you hear the transformer in some of these mics?
« Reply #11 on: June 14, 2009, 02:45:44 PM »

I probably will even prefer the Klaus'd version over the U77, but I do prefer the 60V polarization voltage inside the U77, so then it should be a Klaus'd U87A, not a Klaus'd U87.

SFN
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compasspnt

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Re: Can you hear the transformer in some of these mics?
« Reply #12 on: June 14, 2009, 02:55:38 PM »

Mike Jasper wrote on Sun, 14 June 2009 12:53

I came up with this transformer test after a couple of guys told me, "Of course the mic has a transformer. Can't you hear it?"

I couldn't. And the mic was the Mercenary KM-69.



So you also had a transformerless KM-69 with which to compare?
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MDM,

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Re: Can you hear the transformer in some of these mics?
« Reply #13 on: June 14, 2009, 06:38:59 PM »

Schallfeldnebel wrote on Sun, 14 June 2009 05:49

...I still prefer a Neumann U77 (the first Neumann transformerless microphone from the 70s) over any U87 or U87A.

I rather work with a complete transformerless set-ups, and when I need the specific sound of good transformers,  I insert a transformer in the chain.

SFN




the U77 has a very simple circuit for a transformerless mic, and it's a sort of oddball electronically. Part of the U77 charm is also the capsule.

U77's were made in an era when capsules sounded better in my experience. And the U77 did use a K67, which, in my experience, are superior to the U87's made later on as far as quality, especially in the era of the black-cased 87's

You need transformers for simplicity: a U47 or C12 has only ONE active element, one tube stage, and it will not work unless a transformer is used.

There is a directness in the sound of these simple designs that more than makes up for any 'sound' which may or may NOT be added by a transformer; and transformerless circuits ALSO have a sound- they distort in other ways.

I prefer the tube/transformer idea for this application.
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volki

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Re: Can you hear the transformer in some of these mics?
« Reply #14 on: June 14, 2009, 09:18:56 PM »

In most mic's, a transformer is an integral part of (and mostly specifically designed for) the individual amplifier. Thus, sonic properties are unlikely to be attributable to a transformer alone. The most important component for sonics is still the capsule, though. Many modern mic's come with different capsule designs than the classic ones. Also, current manufacturers utilizing classic electronic designs will use individual capsule designs, etc. etc. - So in order not to compare apples to pears, you would have to A/B different circuit topologies but use the same capsule (and, to be precise, also the same head, grille construction etc.). This has been discussed here at length a few years ago...

The presence of a transformer mostly denotes a classic tube or solid state amplifier, usually with one or two active stages, little or no negative feedback in the first stage, resulting in low order distortion products that rise proportionally with i/p level. Here, the transformer may contribute frequency-dependent distortion (usually at the bottom end), but the general sonic properties will be set by the topology of the whole circuit.
In modern designs, the transformer is no longer needed for impedance matching of the output, which instead is provided by a multitude of transistors (sometimes close to a discrete op-amp), involving a good deal of NFB in order to realize high headroom and minimize distortion. The i/p stage being designed in a similar fashion, the amplifier will impose virtually no distortion before it eventually goes into clipping.

A few personal examples:

- in many situations, I get equal results with both a Neuman UM57 and their M582 head-amp with a UM70 head. Both mics use an M7 capsule and the EC92 tube, but they differ in transformer and (somewhat) in circuit design.
- I once A/B'd a KM84 with a KM54c using a KK64/84 capsule (i.e. both mics sharing the same capsule, but one being a FET the other a tube design) for recording acoustic guitar at ca. 1m distance. There was no significant difference.
- the sonic differences between KM8x and KM18x (meaning, transformer based vs transformerless complex electronics) series mostly result from a revised capsule design in the KM18x which affects the high end

Lastly, an example from AKG's C414 mics from the 80's/90's generation: Two C414 versions, one xformerless (the TL II), one xformer based (the ULS), sharing the exact same electronics. Still, you can't compare them with regard to the xformer, since both mics have different capsules...
So you really have to be aware of what exactly you're comparing.

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