Adam White Posted August 10, 2018 Report Share Posted August 10, 2018 Hey friends. Sent my KM185 in for repair because it was squealing like this. See attached. They sent it it back saying they couldn’t replicate the problem. I was having no problem that day on set though! Humidity or weird RF? This unit was supposedly manufactured after the latest revision but it’s the only things I can think that would be intermittent. Cheers Adam neumann_km185_hissing.wav Quote Link to comment Share on other sites More sharing options...
Eric Toline Posted August 10, 2018 Report Share Posted August 10, 2018 Could be the 48v power in what ever the mic is plugged into. The tone bursts are a bit surprising. If you can't recreate the problem then chalk it up to a one time thing. Quote Link to comment Share on other sites More sharing options...
INARI Posted August 10, 2018 Report Share Posted August 10, 2018 It seems not humidity definitely. and do not hear at midnight if you have heart disease. Quote Link to comment Share on other sites More sharing options...
Adam White Posted August 10, 2018 Author Report Share Posted August 10, 2018 1 hour ago, Eric Toline said: Could be the 48v power in what ever the mic is plugged into. The tone bursts are a bit surprising. If you can't recreate the problem then chalk it up to a one time thing. Never had a problem with another mic. It’s plugged in to a 633... So weird! Quote Link to comment Share on other sites More sharing options...
Constantin Posted August 10, 2018 Report Share Posted August 10, 2018 I can‘t listen to this on my phone, but weird RF is always a possibility, especially with Neumann mics. I have great trouble with my KMR81i with the tx next to the mic on the boom. The mic has no rf protection and Neumann said they won’t do it, either. Maybe a similar issue with your mic? Quote Link to comment Share on other sites More sharing options...
Mirror Posted August 10, 2018 Report Share Posted August 10, 2018 Sounds like your boom op is learning how to play the piccolo. Quote Link to comment Share on other sites More sharing options...
al mcguire Posted August 11, 2018 Report Share Posted August 11, 2018 "It is intermittent, but not all of the time" Quote Link to comment Share on other sites More sharing options...
INARI Posted August 11, 2018 Report Share Posted August 11, 2018 Does not it scream when connected to another device? Quote Link to comment Share on other sites More sharing options...
Adam White Posted August 11, 2018 Author Report Share Posted August 11, 2018 38 minutes ago, INARI said: Does not it scream when connected to another device? Sennheiser returned it to me but I won’t have a chance to test again for a couple of weeks. Thanks everyone for the notes. Quote Link to comment Share on other sites More sharing options...
osborne456 Posted August 12, 2018 Report Share Posted August 12, 2018 30 years with neumann km150, km185 & kmr 81i - from heated Panamanian rain forests to sleety Swedish reindeer running turf- no problems.... so far. Quote Link to comment Share on other sites More sharing options...
mikewest Posted August 12, 2018 Report Share Posted August 12, 2018 Take the outer case off and leave it on a windowsill in direct sun Thanks try mike Quote Link to comment Share on other sites More sharing options...
DSatz Posted April 19, 2019 Report Share Posted April 19, 2019 The KM 180 series uses a DC converter to boost the 48-Volt phantom supply voltage up to 60 Volts to polarize the capsule. The converter basically is a radio frequency oscillator that drives a tiny step-up transformer; its output is then rectified and smoothed. With proper powering and a properly functioning microphone, the frequency of that oscillator is well above the audio range. However, if the microphone is defective or the phantom powering isn't up to specification, the oscillator frequency can dip down into the audible range. You can hear this if you connect the mike to an outboard phantom supply, run it for a minute, then turn the powering off while you continue listening to the microphone's output. As the stored energy in the supply and the microphone ebbs away, the oscillator will drop in frequency, and you will hear it descend through the audible range until it dies out completely. Since Sennheiser didn't find any problem with the microphone itself, I suspect that it wasn't being powered correctly when you ran it. There have been two different versions of the KM 180-series circuitry; the changeover occurred around 2002. The original KM 180-series microphones required 2.3 mA; the later version requires 3.2 mA (in return for which they are 3 dB quieter, while keeping the same sensitivity and maximum SPL). I suggest that you try your microphone with a different preamp, mixer or recorder, or with a known good outboard 48-Volt phantom power supply. The original version of the phantom powering standard set 2 mA as the recommended limit, and a lot of older equipment (and even some that's newer) falls out of spec trying to deliver the 3 to 5 mA that microphones commonly require today, let alone the 7 to 8 mA required in some extreme cases. --best regards Quote Link to comment Share on other sites More sharing options...
Adam White Posted April 19, 2019 Author Report Share Posted April 19, 2019 @DSatz thanks for the detailed reply. Update: I wasn’t crazy. I had someone at the local shop replicate the problem with me, and sent it back in for repair for a second time. It was highly unlikely that the 48v supplied was the problem as we used multiple preamps to test. This time the sennheiser technician heard the problem and repaired it. He wasn’t on his lunch break. I’m afraid I didn’t ask for their detailed repair procedure in the end... I just needed to get back to work! cheers adam Quote Link to comment Share on other sites More sharing options...
DSatz Posted April 19, 2019 Report Share Posted April 19, 2019 Very glad to hear it. Quote Link to comment Share on other sites More sharing options...
Adam White Posted June 21, 2019 Author Report Share Posted June 21, 2019 Another update: The mic that was misbehaving last summer, squealing and what not, has been malfunctioning now in humid environments. And I'm not talking jungles, but a rainy days in Toronto. The noise floor comes up and things get crackly etc. Seems to clear once the air dries it out again. Do we have any KM185 users here that can speak to its "tropical" performance? Is another repair/cleaning in order or is failure expected in humidity for this microphone? AW Quote Link to comment Share on other sites More sharing options...
cstauffer Posted June 23, 2019 Report Share Posted June 23, 2019 Very weird. I too have been using Neumann's for years (KMR81i, KM140, KM150) and have never come across this, and I work in Vancouver. Officially this is a rain forest area. Lots of moisture here. Sorry if you were already asked this, but do you have access to another KM185? Curious if another one does the same thing. CRAIG Quote Link to comment Share on other sites More sharing options...
traut Posted August 9, 2019 Report Share Posted August 9, 2019 I used 184, 185, 81 & 82 for years with never a humidity problem. My Schoeps on the other hand............. Quote Link to comment Share on other sites More sharing options...
Ontariosound Posted August 9, 2019 Report Share Posted August 9, 2019 Adam, you asked many questions but did not share the repair info that took place at Sennheiser. A simple phone call to the Service Department there could give you the info about what was done to your mic and potentially help others on this board. Quote Link to comment Share on other sites More sharing options...
Adam White Posted August 10, 2019 Author Report Share Posted August 10, 2019 1 hour ago, Ontariosound said: Adam, you asked many questions but did not share the repair info that took place at Sennheiser. A simple phone call to the Service Department there could give you the info about what was done to your mic and potentially help others on this board. Hey! Thanks everyone for your responses. It's currently in the Sennheiser shop and I think it's getting a new pcb, at a cost of around $350. I will be calling them next week to get the full story. Quote Link to comment Share on other sites More sharing options...
Eero Kujala Posted January 31, 2021 Report Share Posted January 31, 2021 Did this get solved? I have the same squealing problem with KM185, but only when using through internal coiled cable. Works fine through normal XLR, but when using ICC it needs a whole lot more gain and gets the squealing noise. It's not a problem with either cable as my NTG-3 works fine. Quote Link to comment Share on other sites More sharing options...
r.paterson Posted January 31, 2021 Report Share Posted January 31, 2021 Neumamn km185 is psueda balanced positive is on pin 3 not pin 2..i suspect something with screen on cable as km185vis essntialy unbalnced a balanced microphone like your Rode will work without a screen..do yku have any wirelss hops on bag that could be bleeding thru a bad screen... Quote Link to comment Share on other sites More sharing options...
Eero Kujala Posted January 31, 2021 Report Share Posted January 31, 2021 1 minute ago, r.paterson said: Neumamn km185 is psueda balanced positive is on pin 3 not pin 2..i suspect something with screen on cable as km185vis essntialy unbalnced a balanced microphone like your Rode will work without a screen..do yku have any wirelss hops on bag that could be bleeding thru a bad screen... I tested with only the mic plugged in, so no interference. But yeah, the 2 and 3 pin could be the explanation. Will have to desolder the ICC to recheck and possibly run through a multimeter. Quote Link to comment Share on other sites More sharing options...
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