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First Sound

Subject: First Sound
From: Walter Knapp <>
Date: Wed, 02 Oct 2002 00:49:45 -0400
One of my other hobbies is Astronomy. In that hobby people have a
semi-ceremonial activity they go through. When they get a new telescope,
they set it up for "First Light", the first time it's brought the views
of the stars for the owner. Some make a real ceremony out of it,
choosing carefully what will be first, who will be invited and so on,
others just do it.

Well, this week I'm doing something like that.

Yesterday, the last of 7 pieces bought through 7 different Ebay auctions
   arrived. This was a used Sennheiser MZS 20-1 shockmount. This
shockmount is sold to fit the MKH-20 thru MKH-50 mics. I added a pair of
Rycote suspension clips to replace the ones in it that mysteriously
don't fit the mics above. Then I mounted another Ebay prize, a MKH-60.
Not the official suspension for it, but works just fine.

Not done yet, I mounted to the MKH-60 a pair of dual mount rycote clips
for M/S stereo and the MKH-30 that I got off another Ebay auction.

Now I slipped that whole thing into a Sennheiser MZW-60 zeppelin
windscreen, amazingly the suspension fit it and the two mics cleared.
This was actually the correct one for a MKH-60.

Finally I took the light gray ball of fur that looks like some high
class lady's dog. This one the Sennheiser MZH 70-1, (for the MKH-70
originally). A bunch of careful unstitching, trim 5 1/2" off and sew it
back up and it fits. Wiggle it at my cat and the cat vanishes, must be a
Wookie.

Now take two fabric boot laces, two lines from inside a piece of Canure
Star Quad snake. Pull the core out of the boot laces, slip the fabric
sheaths around the thin cables, put on XLR's. And you have two of the
costly special light, fabric covered cables to put in. Without most of
the cost.

That's 7 scattered ebay auctions, 9 months of watching if you are
counting. Plug it into the MP2 (found used, but not on Ebay) and wander
into the night with a pair of headphones on. Nothing but insects, but
wow! A very good first sound night. Flip the MP2 to decode the M/S
stereo, and it works, in stereo. And all this is fit into a regular size
zeppelin like you would use for just a mono. Want to do mono, it's there
from either mic.

Initial notes, Sennheiser's choice of pretty thick artificial fur does
cut the really high pitched insects a bit. The zeppelin does not, it's a
different construction from a Rycote. The fur should be fine with frogs.
And I have some pieces that are much more open base fabric when I can
get around to it. Next you can't breathe around this setup, except
exactly behind it and very quietly. It can be hand held fine otherwise.
Lots yet to do figuring out how to use this properly. But it's finally
all together and working.

That was last night, today I've been busy with a soldering iron.
Finished the power supply on the MKH-110 based SASS. With some worry,
plugged the mics in and threw the switch, no smoke, a good sign.
Assembled the SASS after trimming the voltages to the mics to specs
(trimpots are accessible with it together as well). It's powered by a 9
volt NIMH battery. Actual fully charged voltage from the battery is 10
volts no load. Mics take 8 volts in a quaint setup unique to them, so I
had to drop it a bit. They are using 8ma each, the LED power indicator
is using a quarter of that. Should have reasonable battery life, and
it's rechargeable. Will take a alkaline 9 volt in a pinch.

Then plugged a 5 pin cable in to the socket on the back of the SASS,
plugged that into my adapter box and that into the MP2. Cross your
fingers, will those nearly 40 year old mics work, time for First Sound.
YES! Love Sennheiser! The insects are extremely clean and distinct. Even
the airliner sounds good. And this thing is very sensitive. Don't shift
your weight or the ground will crunch. It's way less sensitive to
handling noise than the original SASS, so hand holding is easier. It
does pick up from wider than 180 degrees, but you can hide behind it to
breathe. Does not appear to have a dead spot in front center.

This project started to take real shape when Lang put up the parts
numbers for the SASS housing parts almost a year ago now. Then the hunt
for mics. We have a person who for the last 9 months has been auctioning
unused MKH-110's on Ebay one after another. Way cheaper than current
models, this omni is unique in that it's frequency response is 1 -
20,000 hZ. Yes, that's right, this goes down to 1 hZ. Note if you are
offered a model stamped MKH-110-1, it goes down to 0.1hZ, but at quite a
bit lower sensitivity. They are a small enough mic I was able to fit
them in without having to stagger locations.

The problem was verifying how it was powered. Eventually I managed to
get a copy of a diagram by Sennheiser that told what I needed.

There was a bit of interesting machining, try drilling a precise size
hole at a angle through the back and front of a thin housing and keeping
alignment. More details later.

Now I have more fiddling to do. As tested tonight, the mics were exposed
like Lang's setup. I have the covers machined to give them PZM style
slits only. Going to settle that question. And also experiment with how
precise the alignment with the boundary should be.

In due course there will be photos, and sound samples. It does sound
good, seems as good as Lang's MKH-20 version, though we will need side
by side comparison there probably. I need to find some frogs...

Walt




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