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Neumann M269c with -14dB Pad switch Dual-Channel Preamps
Old 26th May 2018
  #1
Here for the gear
 

Neumann M269c with -14dB Pad switch

Hi,

I have a Neumann M269c pair.
One have -10dB pad switch, the other -14dB pad.

Can someone explain about this, please?

Thanks
Old 26th May 2018
  #2
Gear Nut
 

The M269C was never sold in huge numbers, and in fact it was only ever developed because the U67 was shown to several studios/radio stations/ect in Germany and they complained that it didnt fit in with their existing equipment mostly due to the Power Supply, and they requested it could be made to be more compatible with their existing supplies.

I dont know how common this is now but when studios were buying large numbers of mics they could have quite a lot of say (ie look up the M367) So most likely scenario is that someone specifically requested their M269c's with a -14db pad for whatever reason, it is literally just a single capacitor doing the pad in the M269C so would be a very easy thing to change, even now
Old 26th May 2018
  #3
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Klaus's Avatar
 

All U67 and M269 (same exact circuitry except for tube) shipped until early 1962 had -14dB pads. After that, all U67 and M269 were shipped with -10dB attenuation. Attenuation is facilitated by C10, which, when engaged with the switch on the head, parallels the capsule's capacitance. C10 (500pf) was reduced to 270pf in later models, which reduced attenuation by 4dB.

As the M269c model version was not shipped until mid to late 1963, it would have come from the factory with a -10dB switch label and attenuation circuit, not with -14dB.

With other words: the head on a M269c is not original if it has a -14dB switch. Or the switch itself was replaced with one from an older M269 or U67 version. Check serial numbers on both mics: are they close?

Why -14dB initially? Most likely because Steven Temmer, the U.S. importer, and main buyer of U67, had objected to too much output from all Neumann condenser mics when he took over. A 14dB pad seemed like a good starting point, as the now customary 10dB attenuation on condenser mics had not yet been established then.

Last edited by Klaus; 26th May 2018 at 08:55 PM..
Old 26th May 2018
  #4
Here for the gear
 

Quote:
Originally Posted by Klaus View Post
All U67 and M269 (same exact circuitry except for tube) shipped until early 1962 had -14dB pads. After that, all U67 and M269 were shipped with -10dB attenuation. Attenuation is facilitated by C10, which, when engaged with the switch on the head, parallels the capsule's capacitance. C10 (500pf) was reduced to 270pf in later models, which reduced attenuation by 4dB.

As the M269c model version was not shipped until mid to late 1963, it would have come from the factory with a -10dB switch label and attenuation circuit, not with -14dB.

With other words: the head on a M269c is not original if it has a -14dB switch. Or the switch itself was replaced with one from an older M269 or U67 version. Check serial numbers on both mics: are they close?

Why -14dB initially? Most likely because Steven Temmer, the U.S. importer, and main buyer of U67, had objected to too much output from all Neumann condenser mics when he took over. A 14dB pad seemed like a good starting point, as the now customary 10dB attenuation on condenser mics had not yet been established then.
Hi Klaus,
Thanks for your answer.

Yes the number are very close ?45 and ?47 and both microphones have been manufactured in 1964 (Ute from Neumann told it to me after I sent her the serial numbers).

How can I know if it's the head or the switch?
Old 26th May 2018
  #5
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Klaus's Avatar
 

Look through the clear plastic bottom on the head assembly: there should be a small capacitor visible in the center. That is C10. Try to read one of the two values, as outlined in my post

Also, please email me your actual serial numbers. I will look them up and verify model year and features.

KH
Old 26th May 2018
  #6
Here for the gear
 

Quote:
Originally Posted by Klaus View Post
Look through the clear plastic bottom on the head assembly: there should be a small capacitor visible in the center. That is C10. Try to read one of the two values, as outlined in my post

Also, please email me your actual serial numbers. I will look them up and verify model year and features.

KH
I sent you a PM with serial numbers.
The capacitor visible in the center seems to be 470 written on it but that's very difficult to see.
Old 27th May 2018
  #7
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Klaus's Avatar
 

A 470pf capacitor in the head would indicate that indeed someone put an early head on a later M269c.
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