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Author Topic: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?  (Read 9361 times)

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Offline jbou

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Re: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?
« Reply #30 on: January 24, 2013, 11:11:26 PM »
Does anyone have more info on this? I'm currently having some trouble with a similar situation. I have a set of Oktava MK-012 like the OP of this thread and have them running into a box providing phantom power with balanced xlr outputs. I then have a dual xlr to stereo mini plug cable to run the mics into a Roland R-05.... but when I plugged everything in, the R-05 isn't getting any signal. I know the mics are getting power based on plugging the output into the balanced input of a monitor. Based on this thread, I'm guessing it as something to do with how the signal is getting unbalanced to run into the R-05.

Is there a way to wire up a cable to unbalance the Oktava's signal correctly?

After that my options are get a phantom powered recorder or new mics... not exactly what I was hoping for

Offline jbou

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Re: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?
« Reply #31 on: January 25, 2013, 12:38:35 AM »
Thanks for the reply Jon. I really appreciate it. Unfortunately I'm not terribly savvy when it comes to these things. My hope is to find the issue and see if one of TS's cable makers can build me one. If anyone else has any info please chime in!

Offline ttrego2003

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Re: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?
« Reply #32 on: January 27, 2013, 09:19:36 AM »
I'm merely guessing...... In 2002, I purchased a set for matched Oktava MC-012 mics and ran them with a Dmic20 and UA5 with no issues. In 2008, I paired them with Busman Mod PMD-660 and all hell broke loose. Sent the recorder two or three times back to Busman with issues of noise and overloading. Busman finally asked for me to send the Oktava's to him for more tests, he has also mentioned that every pair of mics he owned worked flawlessly. Turns out it was the mics the whole time, they just didn't play well with some gear. Busman modded the mics for a very small fee and i have been in bliss since then. Sorry, I cannot remember all of the technical terms that busman told me. Before you pull anymore hair out,I wouldn't waist anymore time on cables or gear, mod the mics and your problem will hopefully end. Pm me if you have any direct questions (Evan).

Some of the technical peeps here might disagree with but when I was reading your thread, it made remember how frustrated I got when pretty much the same thing happened to me. Best of luck.

Todd

Offline jbou

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Re: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?
« Reply #33 on: January 28, 2013, 01:04:47 AM »
Again, thanks for the replies. I will update if I figure anything out.

Todd did you get my PM?

Offline DSatz

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Re: Modded PS-2 won't work with Oktava MK-012's. Grounding issue?
« Reply #34 on: January 30, 2013, 08:57:10 AM »
Oh, dear. Wish I'd seen this thread sooner. Your PS-2 has been modified so that it converts the signals from your balanced microphones to unbalanced signals, via a wiring scheme that works in many cases but not all--because balanced output circuits can have many possible configurations. No one adaptation scheme works with all of them.

A balanced output has two modulation leads which are independent of shield and/or ground. In many modern microphones, one of those leads is actively driven and the other one has a matching impedance (to create the balance) but is not actively driven. That's perfectly OK when the microphone is connected to a balanced input. But it sounds to me as if the modification on your PS-2 takes the signal from one modulation lead, grounds the other one, and the lead that's being grounded happens to be the one that the microphone is actively driving! So you probably need to connect the wires that go to the tip (left) and ring (right) of the stereo miniplug to the modulation leads for each channel that aren't currently connected, instead of the leads to which they're connected now.

That's only a guess, however. The best procedure is to ask the microphone manufacturer how to unbalance the signals from that particular model of microphone, and follow their instructions carefully. And you should understand that even if you do that and it works, the PS-2 will no longer work with many other types of microphones that have balanced outputs. That's just the way it goes.

For many decades (say, from the 1920s until the mid-1970s) there was pretty strict separation between professional and consumer audio equipment. Any interconnections between the two realms were special-case, one-off situations. There are well-established standards for how to connect balanced equipment such as your Oktava microphones to other balanced equipment, and there are well-established standards for how to connect unbalanced equipment like Sony's consumer microphones to other unbalanced equipment such as your Sony consumer recorder. But there is no standard way to connect a balanced microphone (or other balanced signal source) to an unbalanced input, and because balanced output circuits vary so much, there can never be one. There is no such thing as an "adapter from balanced to unbalanced" (e.g. from a pair of XLRs to a stereo mini-plug) that can possibly work given all the various kinds of balanced output circuits that exist. People shouldn't buy or sell adapters that supposedly do that--it's deceptive, unethical, and can lead to things just not working, or even being damaged.

You can convert an unbalanced input into a balanced input by putting an input transformer in front of it, but that can get expensive if you want the transformer to be really good at passing wide-range audio signals, and it can also be a little awkward logistically. Or you could use a preamp with phantom powered, balanced inputs and unbalanced "aux" outputs--there are plenty of those around.

--best regards
« Last Edit: January 31, 2013, 09:34:30 PM by DSatz »
music > microphones > a recorder of some sort

 

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