| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 2625.1 | detached | VICE::JANZEN | A Refugee From Performance Art | Wed May 01 1991 11:51 | 10 |
| detach the element from the little metal board
and attach it to a big board a meter on a side.
This improves bass response.
Use the higher voltage batteries (cf. the directions with the unit).
This improves signal strength and maybe ? signal/noise.
I use them to record my performances. They pick everything with low
noise. I wish I had 2 of them to record in stereo. Stereo with
those is probably awesome
They're great mounted on the bottom of piano lids (with tape)
Tom
|
| 2625.2 | | MALLET::BARKER | Pretty Damn Cosmic | Wed May 01 1991 12:43 | 13 |
| Brian Rost kindly mailed me a set of instructions. It actually requires
rather more butchery than I am prepared to indulge in at the moment but is
actually quite simple. The big advantage it gives you apparently is to be able
to have long e.g. 75ft cable runs using a pseudo-balanced line.
I am actually very happy with them at the moment. Does anyone know
about any other potentail drawbacks, I guess the big one is that they are
omni-directional and could pick up too much background noise if used e.g. as a
vocal mike. As Tom says they should be toadally awesome in stereo. They would
be very suitable for live recordings of ensemble playing although because of
their omni-directionality a noisy live audience might be too intrusive.
Nigel
|
| 2625.3 | audience | VICE::JANZEN | A Refugee From Performance Art | Wed May 01 1991 12:57 | 13 |
| Yes they pick up the audience, that's why I liked them, to pick up
laughs. The only way to make them directional is to mount them on the
1 meter square boards and point the boards at the ensemble away from
the audience. So the boards would be standing up almost, maybe
at an angle of 75 degrees to the floor,
I'm just making this up as I go along, based on the directions with
the mike.
board
\ O O O O
audience \\ pzm ensemble
O O O O O O __\___________________________
Tom
|
| 2625.4 | one live and one from the mixer/amp | COGITO::SULLIVAN | Singing for our lives | Wed May 01 1991 14:11 | 11 |
|
I've made some excellent recordings of live folk music with my
Tascam Porta-one by recording directly from my (combo mixer and) amp
on one channel and with a PZM on the other channel. Then when I mix
down to a Dolby deck, I can bring up the live mic. during sing alongs
and bring up the channel from the amp on quieter ballads or songs with
quieter instrumentals. Has anyone else tried this method? Would I be
better off using 2 PZMs and just recording the live sound? When I've
recorded just from the amp, I haven't liked the sound.
Justine
|
| 2625.5 | I can use some tips also!! | NWACES::PHILLIPS | | Wed May 01 1991 14:13 | 14 |
| I got one and have been experimenting with it. While I like the clarity
it picks up every thing, trucks passing outside, toilet flushing
upstairs so I use it late at night when all is still and quiet.
My problem is with placement, I have to be 1 foot away to get a hot
signal, but then then I get too much string noise (from my acoustic
guitar).
I haven't been able to get the hotter batteries mention in booklet
with the mic,I did check a couple of RS stores. Also I haven't been
mounting it to a 4X4 piece of ply wood, is that really important?
Will it really improve the sound?
I just don't happen to have a piece of ply wood around that I can use.
Errol
|
| 2625.6 | RE: Hotrodding PZMs | DWOVAX::ROSENBERG | Damn Good Coffee ... and HOT! | Wed May 01 1991 14:25 | 14 |
| Nigel,
Sorry, I don't have an answer for you about the PZMs, but if you do
find out how to "hotrod" them, please let me know. I have a pair
myself, and the high end is rather gritty.
I *DO* know that you can change the batteries from single AA's to
two mini 3 volts (I think), and this increased BASS fidelity. I.E.
two half size batteries fit into one microphone. I've done this and
noticed a slight difference.
Let me know what you find out.
Ken Rosenberg
|
| 2625.7 | 2 + 2 | IXION::ROST | Lobster in cleavage probe | Wed May 01 1991 14:27 | 17 |
| Justine,
We do something similar when we tape shows at the coffeehouse in
Worcester. We have a stereo feed off the board, then have two
omnidirectional mikes placed in the back of the room to pick up room
ambience and crowd sounds (clapping as well as singalongs). We mix the
two stereo signals together right to stereo tape.
This is a time-honored method that works well in cases where the PA
sound is pretty clean (usually not the case with rock bands in clubs,
though).
Worcester area noters who want to hear this in action tune in WICN 90.5
at 7 PM or thereabouts on Wednesday evenings for "Coffeehouse
Connection" which is where the tapes get aired.
Brian
|
| 2625.8 | Just the Mods, Ma'am | IXION::ROST | Lobster in cleavage probe | Wed May 01 1991 14:29 | 174 |
| Here's the mods, from a USENET posting a few years ago. The basic idea
is that the PZM can run with much higher supply voltage than 1.5V,
and the increased voltage improves dynamic range considerably.
Brian
This article or any form thereof may not be used for profit or
republished in any way without written permission from the author.
Distribution is granted to subscribers of this electronic network
news service for personal use only.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
> <
> CAVEATS: <
> <
> All appropriate warnings about voiding warranties and possible self <
> destruction of equipment, and safety hazards to your person apply <
> here. If you're careful, you'll get a nice piece of gear; if you're <
> not, you'll have a smouldering piece of junk, or you may obtain <
> electrical burns, or you may even die. I assume no responsibility <
> for any results, good or bad. These mods assume that you have <
> good technical ability in that you know what you're doing when <
> modifying a circuit. Always be careful and work safe. These <
> modifications are not recommended for novices. If you doubt your <
> abilities, don't attempt these modifications. <
> <
> READ EVERYTHING BEFORE STARTING. <
> <
> The author assumes no responsibility for erors <
> that may apppear in dis articl. <
> <
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Introduction
The RS/Crown PZM microphone is an omnidirectional electret microphone
having an output impedance of about 600 ohms. It requires from 1.5V to
12V DC for operation. The stock microphone has a supply module and
built-in line matching transformer to convert 600 ohms unbalanced to about
10K ohms unbalanced. The problem with this PZM is twofold:
1) you cannot use long cable runs on the mic since the line is unbalanced
2) the matching transformer used in the module is terrible
So the mods outlined below address these two problems by describing
a method of using a standard balanced microphone cable in conjunction with
an unbalanced (single-ended microphone input configuration. There are
compromises made when using this approach, but the benefits far outway
the compromises.
Modifying the Radio Shack/Crown PZM microphone
The stock assembly consists of a mic, a coax cable, a supply module, a
twinax (2-wire shielded) cable and a 1/4" phono plug as shown next.
----- --------------
|mic|---coax cable-----|power supply|----twinax cable---1/4" phono plug
----- --------------
1. Cut off the 2-wire shielded cable between the 1/4" plug and the power supply.
Toss the phono plug.
2. Take the mic apart (screws on the bottom). Unsolder the coax cable from
the mic element and replace with the 2-wire cable from step #1 above.
Connect the low side to the dark color wire and high side to the light
color wire. DO NOT CONNECT THE SHIELD TO THE LOW SIDE!
3. Connect the other end of the 2-wire cable to an in-line male XLR
connector. You should now have something that looks like this:
male XLR
mic n/c --------------------------------------- shield (pin 1)
electret high -------light wire---------------------- pin 2
element low -------dark wire----------------------- pin 3
4. Make some long mic cables from some twinax or 2-wire microphone cable.
I made three 75' and three 25' cables for my setup. Shields are connected on
each end to pin 1 and the case on one side (I think it's the female side)
as shown next.
female XLR male XLR
case------shield --------------------------------------- shield (pin 1)
high --------------------------------------- pin 2
low --------------------------------------- pin 3
The next step is to build an in-line supply that also adapts the XLR
connectors to a 1/4" phono mic input of most tape recorders as shown next.
There should be one of these supply boxes built for each mic used.
-----------------------
female XLR-------|supply/adapter module|-------------1/4" phono plug
-----------------------
5. Cut a 24" piece of 2-wire mic cable and connect an in-line female XLR to
it as you did in step 3 above.
6. Cut a 24" piece of coax and connect an in-line 1/4" male phono plug to
it.
7. Cut holes large enough in a small steel project box to run the cables
through. Add chaffing and strain relief to these two cables.
8. Connect the shields from the two cables AND the low side of the 2-wire
mic cable to the same point (single point) on the project box.
9. Connect the "+" side of a 9V transistor radio battery jack to this
single point ground.
10. Connect the "-" side of this battery jack to a 2.2K ohm 1/4 watt resistor.
11. Connect the other end of the resistor above to the high side of the
2-wire cable.
12. Connect a 10 uF mylar or metalized polypropylene capacitor from the
high side of the 2-wire mic cable to the center conductor of the coax
cable.
You should now have something that looks like this:
female
XLR 1/4" phono plug
1 ---shield-----|-------- single-point ground----------------shield-----
3 ---low--------- | ------hot--------
2 ---high----- ----- "+" "-" --- 2.2K ohm ----- |
| 9 volt | |
| battery | |
|--------------------------------------- |
| |
--------------||---------------------------
10 uF
input
cap.
When the mics are not connected, there is no drain on the battery so there
is no need for a switch.
Close up the project box and plug in the microphones and the tape recorder.
I think you'll be surprised by the improvement in these otherwise inexpensive
and ho-hum mics.
One last note, if you are ABSOLUTELY POSITIVE that the input stage of your
tape recorder has an input capacitor and then a load resistor, you can replace
the 10 uF cap with a piece of wire. (See below.)
REPLACE THE CAP WITH WIRE IF USE THE INPUT CAP ABOVE IF
THE TAPE DECK INPUT LOOKS LIKE THE TAPE DECK INPUT LOOKS LIKE
THIS: THIS:
input input
cap cap
jack----||--------input stage jack----------||----input stage
| |
load load
resistor resistor
| |
ground ground
You should also replace the input caps of the tape deck in either of the
above two cases with an equivalent value equal or higher voltage mylar or
metalized polypropylene capacitor to obtain the best performance.
Yours for higher fidelity,
Phil Rastocny
AT&T-ISL
11900 N. Pecos St.
Denver, CO 80234
..!drutx!pmr
Disclaimer - My employer had nothing to do with the creation of this
article.
|
| 2625.9 | Which Mod ? | CITYFS::SM | Not now, I'm eating my lunch!!! | Wed Jun 26 1991 11:59 | 10 |
|
There was a phantom power mod for the PZM in the U.K. mag "Home
Recording". This involves reversing the polarity on the mic capsule
and some circuit changes. This gets ugly if you havent got Aluminum
solder and steady hands.
THe PZM's come with balanced circuitry by default but they only put
a phono jack on the end , so all you need is an XLR connector and
a bread knife.
|