J. Young wrote:
> I'm trying to get Sennheiser to look around for any info that they may find
> for the
> MKH 110. Too bad their web site is only good for their latest products and
> really
> not much info on them either.
> I'd like to find more info on that mkh 104 power supply, etc. that you
> mentioned.
> That may give me an idea about how to proceed. I'd really hate to put a
> soldering
> iron any where around this mic without a good plan.
Note that you would have to adapt the MZA-6 power supply. The MKH-104
uses 8 volts, but reverse polarity to the MKH-110, it's not the same.
The circuit for the MZA-6 shows pin 1 & 2 passing straight through, with
the battery stack connected between 2 & 3 with the pin 2 side positive.
They also show the shield tied together all the way from amp to mic. But
when you reverse the 8 volts for the MKH-110, the shield needs to be
broken, at least if doing a pair into the same pre. Otherwise the shield
becomes the feedback pathway for a nasty oscillation between the two.
Assuming your pre used a cap in it's input to cut off the DC, all you
would have to do with the MZA-6 is reverse the batteries. The original
used 6 RM-625 mercury batteries. The MKH-104 has lower current draw, and
from their specs they got 50 - 60 hours on a set of batteries. That
would work out to about 30 - 35 hours for a MKH-110. Which is why I
noted it would be expensive to keep fed batteries.
Note that the MZA-6 diagram shows a mic pre front end that's isolated
with a cap internally. If your mic input cannot handle 5-6 volts DC on
the signal line itself, you would need to build a cap into the MZA-6.
Their MZN 4/1 power supply (for AC) feeds a zenar regulated 12 volts
into a 800 ohm resistor to drop voltage. Then the usual filter cap. Do
note the resistor size is dependent on current as well as voltage. Mine
works out somewhere around 190 ohms to drop off 10 volts, the current is
higher.
I have Sennheiser's pamphlet of the period. It does not cover the
MKH-110, but covers the others, including circuit diagrams for the
various power supplies. And photos of most of them. Too bad they did not
detail the MKH-110 in there. I could scan things out of there, but it's
really not going to help.
When I had Sennheiser look around, all I got was the circuit diagram
that I scanned and a table of the basic specs. It will be interesting to
see if you can get anything different. I had another source claim to
have info, and when that arrived it was the same diagram. I did not try
the parent company in Germany, only the US part.
Note the inside of the MKH-110 is stuffed from end to end with circuit,
it would be very tricky to design in some circuit to work off phantom
power. The housing is also part of that circuit, so it would be also a
challenge to machine a larger housing. I'd expect the RF circuit might
have to be retuned if you did that. And I've not the least bit of info
on that.
Walt
________________________________________________________________________
________________________________________________________________________
|