[[email protected]]

I have the SONY RH1 minidisc recorder, and recently got binaural
microphones from Sound Professionals ( MT350 ). When I run the
recorder on mains power, I get a real buzz on the recording. SP tells
me that I should record on battery power only, and this does indeed
solve the problem, but I really want to be able to use ac whenever
possible. The SONY 907 mic works fine with no buzz, even on AC power.
(The SP mics get their power through the recorder, the SONY has a
battery.) Any suggestions on what to do next? Get an ac line filter?
If so, where from? Get new mics? If so, any suggestions? I do want
to upgrade from the 907, and am thinking of spending up to about $150.
Thanks for any advice - I'm technically not very savvy, so please spell
it out!
Cheers.

[Richard Crowley]

wrote ...
I have the SONY RH1 minidisc recorder, and recently got binaural
microphones from Sound Professionals ( MT350 ). When I run the
recorder on mains power, I get a real buzz on the recording. SP tells
me that I should record on battery power only, and this does indeed
solve the problem, but I really want to be able to use ac whenever
possible. The SONY 907 mic works fine with no buzz, even on AC power.
(The SP mics get their power through the recorder, the SONY has a
battery.) Any suggestions on what to do next? Get an ac line filter?
If so, where from? Get new mics? If so, any suggestions? I do want
to upgrade from the 907, and am thinking of spending up to about $150.
Thanks for any advice - I'm technically not very savvy, so please
spell
it out!

I would return as defective any microphones that worked like that.
Buy microphones from someone who doesn't give you such a lame
excuse.

Assuming there isn't something wrong with the "plug-in power"
on your recorder. Can you go to a retailer somewhere, or
borrow a microphone from a friend that runs on "plug-in-power'
to confirm that the problem isn't your minidisc recorder?

[Geoff]

wrote:
I have the SONY RH1 minidisc recorder, and recently got binaural
microphones from Sound Professionals ( MT350 ). When I run the
recorder on mains power, I get a real buzz on the recording. SP tells
me that I should record on battery power only, and this does indeed
solve the problem, but I really want to be able to use ac whenever
possible. The SONY 907 mic works fine with no buzz, even on AC power.
(The SP mics get their power through the recorder, the SONY has a
battery.) Any suggestions on what to do next? Get an ac line filter?
If so, where from? Get new mics? If so, any suggestions? I do want
to upgrade from the 907, and am thinking of spending up to about $150.
Thanks for any advice - I'm technically not very savvy, so please
spell it out!
Cheers.

POssibly it is using a SMPS power supply. Try a linear one instead.

geoff

[Laurence Payne]

On 13 Jan 2007 11:08:45 -0800, wrote:

I have the SONY RH1 minidisc recorder, and recently got binaural
microphones from Sound Professionals ( MT350 ). When I run the
recorder on mains power, I get a real buzz on the recording. SP tells
me that I should record on battery power only, and this does indeed
solve the problem, but I really want to be able to use ac whenever
possible. The SONY 907 mic works fine with no buzz, even on AC power.
(The SP mics get their power through the recorder, the SONY has a
battery.) Any suggestions on what to do next? Get an ac line filter?
If so, where from? Get new mics? If so, any suggestions? I do want
to upgrade from the 907, and am thinking of spending up to about $150.
Thanks for any advice - I'm technically not very savvy, so please spell
it out!

It seems that the plug-in power on your Sony is noisy, when the AC
adaptor is connected. You can blame this on the power adapter, the
recorder or the microphone. Maybe even on your mains power. You may
be able to solve it by building a simple battery power supply box to
go between mic and recorder. This would be, I think, cheap and
simple enough to be the thing you try first. Can someone point to a
suitable circuit?

[Richard Crowley]

"Laurence Payne" wrote ...
It seems that the plug-in power on your Sony is noisy, when the AC
adaptor is connected. You can blame this on the power adapter, the
recorder or the microphone. Maybe even on your mains power. You may
be able to solve it by building a simple battery power supply box to
go between mic and recorder. This would be, I think, cheap and
simple enough to be the thing you try first. Can someone point to a
suitable circuit?

The circuit is trivial, but should not be necessary.
Something is broken here and should be repaired
or replaced.

[Laurence Payne]

On Sat, 13 Jan 2007 18:17:59 -0800, "Richard Crowley"
wrote:

It seems that the plug-in power on your Sony is noisy, when the AC
adaptor is connected. You can blame this on the power adapter, the
recorder or the microphone. Maybe even on your mains power. You may
be able to solve it by building a simple battery power supply box to
go between mic and recorder. This would be, I think, cheap and
simple enough to be the thing you try first. Can someone point to a
suitable circuit?

The circuit is trivial, but should not be necessary.
Something is broken here and should be repaired
or replaced.

Indeed. With hindsight, some part(s) of this system probably should
not have been purchased. But they have been, and there may be an
easy fix. Can you point us to a source of the trivial circuit,
please?

[Richard Crowley]

"Laurence Payne" wrote ...
"Richard Crowley" wrote:

It seems that the plug-in power on your Sony is noisy, when the AC
adaptor is connected. You can blame this on the power adapter, the
recorder or the microphone. Maybe even on your mains power. You
may
be able to solve it by building a simple battery power supply box to
go between mic and recorder. This would be, I think, cheap and
simple enough to be the thing you try first. Can someone point to
a
suitable circuit?

The circuit is trivial, but should not be necessary.
Something is broken here and should be repaired
or replaced.

Indeed. With hindsight, some part(s) of this system probably should
not have been purchased. But they have been, and there may be an
easy fix. Can you point us to a source of the trivial circuit,
please?

The circuit is a ~2.5K ohm resistor to a 3-5V supply of
clean DC, with a blocking capacitor of your choice. Google
returned 522,000 hits for: diy microphone battery box.

The problem here is that whatever AC hash is going
upstream through the microphone connection (assuming
that is the apparent problem) will NOT be solved by an
external power source. The AC coupling through the
blocking capacitor will faithfully carry the undesired
noise just as surely as it is flowing now.

And if the problem is that some kind of EMI is being
picked up by the microphone/cable, the battery box
won't help that, either. The microphone already
converted the EMI into audio before it got to the
battery box.

If the problem is in the MD player, no fooling around with
external battery boxes is going to solve the problem. If
the problem is in the OP's microphones, they appear to
be inexpensive ($5) throw-away things.

[[email protected]]

Thanks for all your thoughts. As you say, something is broken here and
needs repairing or replacing.
I tried different locations (200 miles apart) to see if the power
supply was the problem. No difference there.
I contacted SONY who sent me a replacement adaptor. That didn't change
anything.
I haven't had a chance to try another plug-in power mic yet, but I did
get to try the SP mics with an iHP120. The result was exactly the
same: no problems on battery power, a buzz while using them with mains
power. So it seems to me that this is where the problem is, even if
Sound Professionals are of the opinion that I should just use battery
power and be done with it. The mics weren't throwaways ($100) and I
still have a few days during which I can return them. This is what I
should do, yes?
The other solutions are too complicated for a non-techie!!!
I'm a classical musician who just wants to record rehearsals and
concerts (mostly chamber music), so a small portable mic is desirable.
Any suggestions?
Thanks for anything more you can offer!