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Author Topic: Neumann U89: Why So Little Discussion Compared To AKG 414?  (Read 30316 times)

Klaus Heyne

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Re: Neumann U89: Why So Little Discussion Compared To AKG 414?
« Reply #30 on: August 26, 2010, 02:21:29 PM »

Back to the topic:
When I look at a schematic of a multi-patten, dual-diaphragm mic, I make note of the one pattern selectable that does NOT involve portions of rear-capsule side polarization voltage added to the pure cardioid of the front.

Usually, the theoretical advantage of the precise electronic shaping of the front side pattern through adding rear pol. voltage- whether it is to get the pattern wider (in phase addition) or narrower (out-of-phase addition)- is reduced by the audible artifacts these electronic manipulations bring with them.

That's quite audible in the case of the AKG 414 and Neumann U89 in hyper-cardioid; it's also audible in the case of the M149, whose true electric front side-only operation is in wide cardioid. In cardioid, a small amount of rear side voltage is added out of phase, in an attempt to mitigate the perceived shortcomings of the relatively wide acoustic cardioid pattern of the K49 capsule.


Make some tests for yourself and decide which pattern in these multi-pattern mics sounds most natural and engaging.
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Klaus Heyne
German Masterworks
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David Bock

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Re: Neumann U89: Why So Little Discussion Compared To AKG 414?
« Reply #31 on: August 26, 2010, 02:32:10 PM »

Quote:

Diocletian wrote on Thu, 26 August 2010 06:28
I recall a Gotham Audio ad for the U89 in REP exclaiming "Remember the M49?"
Is that the sound Neumann was searching for
In that case, Neumann would have used a K49. I think that the K89 is more neutral than the K49.

mmmmmmm I installed a k49 on my tlm 170 and finally made it useful. It's actually better than a fet 47 on kick drum in a live combo setting since it cuts out more room than the fet 47, yet retains the essential mids and 'tick' sound of a kick on a 47fet. Surprising, in a good way. Haven't even thought of trying it on anything else.

Schallfeldnebel

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Re: Neumann U89: Why So Little Discussion Compared To AKG 414?
« Reply #32 on: August 26, 2010, 06:43:17 PM »

Klaus you wrote:" In cardioid, a small amount of rear side voltage is added out of phase, in an attempt to mitigate the perceived shortcomings of the relatively wide acoustic cardioid pattern of the K49 capsule."


It is the opposite. The pattern of the K49 when only used on one side is a cardioid with a tendency to super-cardioid in the higher regions, and to make the narrow pattern more wide, a positive charge is put on the backside of the capsule.

SFN

I quote Mr. Martin Schneider from Neumann:

The standard K47/49, just like the M7 is an in-between capsule. Cardioid somewhere below 1kHz, super/hypercardioid the higher you go. That's the way the capsule came out of the design process in 1935. And that's why the manual for U47fet said 'supercardioid'.
Thus, the M147 has the polar pattern of a U47 or U47fet, tendency towards super/hypercardioid, as there's no polarisation voltage on the rear half.
In the M149, when set to cardioid, we put some volts on the rear half, so the setting 'cardioid' does mean 'best possible cardioid for this capsule', and does NOT mean 'zero volts on the rear'.
For 'zero volts on the rear' in the M149 you have to select the intermediate setting between cardioid and hypercardioid.
Note: The M49 had a potentiometer. There, 'cardioid' meant 'zero volts'. Interestingly, to my knowledge, the M49s were mostly used not at 'zero volts' but at 'best cardioid' setting. Some users even made marks on the potentiometer at 'best cardioid' setting. That's why we chose the above approach with M149.
Best regards, Martin Schneider Neumann Mic. Development
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Klaus Heyne

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Re: Neumann U89: Why So Little Discussion Compared To AKG 414?
« Reply #33 on: August 28, 2010, 01:16:41 PM »

You are right. I should have said:
"In cardioid, a small amount of rear side voltage is added in phase, in an attempt to mitigate the perceived shortcomings of the relatively narrow acoustic cardioid pattern of the K49 capsule."

Interestingly, my incorrect description was derived from my personal experience with these capsules: rather wide cardioid in the low-mid frequencies.
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Klaus Heyne
German Masterworks
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Jim Williams

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Re: Neumann U89: Why So Little Discussion Compared To AKG 414?
« Reply #34 on: August 30, 2010, 11:29:25 AM »

Having reworked many U89 circuits and their similar counterparts in the fet 47 and KM81/82 shotguns, it's not a bad circuit. It's esentially a discrete opamp design. The parts are lacking. The BC series bipolar transistors spit in the high mids, very un-flattering. The Wima polycarbonate coupling capacitors are also spitty and hard on transients.

There are also frequency response fixes and some bandwidth adjustments. Once reworked, it's a very open and smooth mic. The output transformers damp the tops more than the circuits do once one addresses those problems.

If you want to hear a U89 capsule without that circuit, check out an original TLM170 made in the late 1980's.
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Jim Williams
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Martin Kantola

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Re: U89? why so little discussion? compared to 414?
« Reply #35 on: August 31, 2010, 05:19:02 PM »

dbock wrote on Wed, 25 August 2010 23:16

Theoretically, that mid sized capsule has some ideal compromises. I wonder if anyone has tried it with either a simple fet amp (a la u87) or tube amp


Have built a tube mic with this capsule, did not sound bad to me.

Martin
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