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MC930, one of pair 6dB down

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MC930, one of pair 6dB down

Postby hooty2 » Tue Jul 09, 2019 2:55 pm

Hi...
Before i attempt a look inside and before sending for pro assessment/repair...
Any first thoughts on:
Matched pair - Beydynamic MC930,
One of which may have been dropped, is 6/7dB lower in level compared to other in pair and a second matched pair.
The end ring (business end)...rotates left/right maybe 1/2 mm...all others are firm.
Noticed on location then tested with pink noise.
Sound quality seems ok.
Best thoughts anyone?
Cheers
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Re: MC930, one of pair 6dB down

Postby Sam Inglis » Tue Jul 09, 2019 3:03 pm

Could be that you're only hearing one leg of a symmetrical balanced output?
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Re: MC930, one of pair 6dB down

Postby hobbyist » Tue Jul 09, 2019 3:41 pm

hooty2 wrote:Hi...
Before i attempt a look inside and before sending for pro assessment/repair...
Any first thoughts on:
Matched pair - Beydynamic MC930,
One of which may have been dropped, is 6/7dB lower in level compared to other in pair and a second matched pair.
The end ring (business end)...rotates left/right maybe 1/2 mm...all others are firm.
Noticed on location then tested with pink noise.
Sound quality seems ok.
Best thoughts anyone?
Cheers

Depends........... a lot

How important is the matched pair
Is it just the gain or also freq response
Has the NF changed
Has the pickup pattern changed

Can you afford to fix/replace it
Will it keep changing

You need to balance your budget vs your needs and decide.

For me, and I am sure my needs are different from yours,
I would put it last in my bag for use when absolutely necessary and then just tweak the gain when I did. But I do not have the money to buy mikes like this nor even to repair them.

Worst case *I* might try to go inside and see if there is anything obvious that needs fixing. You need to evaluate your own sitrep.

I might see if I could replace the rotating cap with a new one if that part is what is keeping it from rotating. If the inside is the culprit I would write it off unless they can put the innards in a new container at a reasonable cost. But then would it still be a matched pair?

How important is the matched pair aspect? How matched were they initially anyway?
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Re: MC930, one of pair 6dB down

Postby Sam Spoons » Tue Jul 09, 2019 4:21 pm

Sam Inglis wrote:Could be that you're only hearing one leg of a symmetrical balanced output?

Yup, 6dB down definitely ties in as does the rotating/loose ring suggesting a broken connection on one leg of the circuit. if the sound quality is still good apart from the low level that suggests the capsule is still ok so it sounds likely to be a relatively easy fix and definitely worth attempting.
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Re: MC930, one of pair 6dB down

Postby Hugh Robjohns » Tue Jul 09, 2019 4:31 pm

Sam Inglis wrote:Could be that you're only hearing one leg of a symmetrical balanced output?

Yes, that would be my guess. Any sudden loss of 6dB or so immediately suggests to me that one side of a symmetrical balanced output driver has died.

In which case, it will need the attentions of a microphone mechanic... ;-) Polar Audio are the agent in the UK:

POLARaudio Ltd.
Unit 3 Clayton Manor Victoria Gardens
RH15 9NB
Burgess Hill West Sussex

Tel.: 0044 1444 258258
Fax: 0044 1444 258444
sales@polaraudio.co.uk
www.polaraudio.co.uk

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Re: MC930, one of pair 6dB down

Postby Hugh Robjohns » Tue Jul 09, 2019 4:41 pm

hooty2 wrote:The end ring (business end)...rotates left/right maybe 1/2 mm...all others are firm.

beyerdynamic_mc930.pdf_2.png


The end ring is the capsule, which -- I think -- screws on. It's obviously been loosened by the fall, and possibly dented/damaged which may be why it only rotates a small amount... but I doubt that would affect the mic's sensitivity or output level. (The diagram above shows a grub screw on the side near the top which may secure the capsule, but I think it probably secures the inner collar. Careful examination should reveal how it's all put together and if anything has worked loose.

As for sounding okay... well if it has lost one side of the output driver it wouldn't sound any different, other than being 6dB quieter... but it will be massively more prone to picking up interference because the balanced output is probably no-longer properly balanced from an impedance to ground point of view.

The output XLR looks like it is attached directly to the PCB, so it's possible that a solder joint there has fractured and gone open-circuit. If so, that might be fixable as a DIY job, but since it's a matched pair if anything needs replacing I think I'd be more inclined to leave it to the experts to be sure of maintaining the matching...

The MC930 is a pretty decent mic. It would be worthwhile getting it properly fixed in my opinion.

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Re: MC930, one of pair 6dB down

Postby hooty2 » Tue Jul 09, 2019 4:57 pm

Great stuff!
All views and options appreciated.
I'm contacting polar audio next.
Regards to all for pitching in.
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Re: MC930, one of pair 6dB down

Postby Wonks » Tue Jul 09, 2019 6:16 pm

You have of course swapped the cables around first to ensure it's not a cable issue and that it is the mic?
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Re: MC930, one of pair 6dB down

Postby hooty2 » Tue Jul 09, 2019 7:40 pm

Fearlessly!
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Re: MC930, one of pair 6dB down

Postby Hugh Robjohns » Tue Jul 09, 2019 8:16 pm

:thumbup: :clap:
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