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2 Different microphone repair situations. Condenser Microphones
Old 21st April 2015
Here for the gear

2 Different microphone repair situations.

I've got one emergency repair question, and one slightly less time sensitive question more about a more involved microphone job.

1st -

Last night, breaking down after a live show, the engineer that was hired knocked over my U87. It is now crackles to the point that it is unusable.

I really, really need this mic, as it gets used as much as anything I have. I'm hoping that, since it is a pretty straightforward common mic, there is someone out there who can get it looked at quickly.

Bonus points for anybody in the Houston, TX area. I'm going to be in trouble without this microphone. Given the ubiquity, I'm thinking I can try for speed. But if I'm off base and just need to bite the bullet and send it to a "master" specialist and wait however long, please let me know.

2nd -

I have a pair of really, really old Altec M30's. I'm pretty sure they haven't been out of the closet since about 1960. All the rubber parts are degrading. One of the power supplies doesn't even have the 4665 transformer - it terminates in a single ended 1/4" phono cable! The actual capsules and microphones appear fine, but I'm thinking the big electrolytic caps in the power supplies at the very least as well as pretty much all the cabling will need to be replaced.

I know Bill Hayes is supposed to be the be all/end all when it comes to Altec mics. I've tried to contact him 4 or 5 times over the last two years since I got the mics, and I haven't gotten a response so I'm thinking he's just not going to be available for me.

Is there a 2nd option that you'd contact? It is going to be almost as much a total rebuild as a repair. I'm happy to wait as long as it takes with these. I know it's going to be an extensive, involved repair/rebuild job.

Thanks for your help.


Old 22nd April 2015
Gear Guru
kafka's Avatar
Microphone Repair

Tom Onofrio did a fantastic job on my KM's. Super fast turnaround, and I don't know how he can work at his prices. Anything that I don't need to send overseas that he can handle will go to him.

Neumann Mic Tech went independent
Old 22nd April 2015
Here for the gear


I'm going to try to get in touch now, I very much appreciate it.
Old 26th April 2015
Gear Head

KBlodgett: Email or call Tom Onofrio. He worked on one of my Neumanns. Did a nice job and the price was right. My guess is something got knocked loose when your mic fell over. A good reason to use a 25 lb barbell weights to ballast mic stands.

The Altec M-30: Not a bad mic...Download schematics of the mic and power supply before working on these. If you fire these up after years of storage, bring up the supplies (with the mic connected) slowly with a variac on the AC. I assume you are using the 525A power supplies. Let the supplies stabilize before making any decision concerning hum, etc. If a voltmeter is available, check the DC supply for the 5840 should be around 5.6 volts. Note that the mic sends audio down the cable to the power supply unbalanced, off the cathode of the 5840. Most of the power supplies had a transformer to match the unbalanced cathode load to a more useable 200 is not surprising the unbalanced version terminated in a phone plug. The original transformer may be hard to find. Get out the soldering iron, get a octal plug, look in spare parts, and wire a suitable output transformer (like a UTC O-8, A-25, or a suitable Jensen) to the corresponding pins for the Altec plug in. The mic should work.

BE CAREFUL when working on the power supplies. Voltages on the power transformer and some of the components is dangerous. The filter capacitors can hold a charge long after the unit is turned off. If you get excessive hum, the power supplies may need to be recapped. Some of the multisection can electrolytic capacitors are being manufactured by a firm in the states catering to tube audio equipment repair parts.
Old 27th April 2015
Lives for gear
Motoxxx's Avatar

Also Dave Brown at * Microphones - Agoura, CA - Microphone Repair did a fantastic job on two of my Neumanns. Super nice guy and really knows his stuff. He did a really great job of dealing with Sennheiser/Neumann to get their own part numbers corrected too! Very reasonable pricing and very fast turn around.
Old 16th October 2015
Here for the gear

Neumann M49b -- good as new, thanks to Tom Onofrio

Tom Onofrio really dialed-in my Neumann M49b a couple weeks back -- it looks and sounds terrific. His expert care brought the mic's character back to life. I noticed a marked improvement in the detail and clarity while tracking some acoustic guitar and vocals this past week.

Prompt and quality service. I'm recommending Tom to all of my friends and associates for sure.

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