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Author Topic: Realistic PZM mods - PZM Boomerang v1.1 (now with audio clip)  (Read 12560 times)

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Roving Sign

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Realistic PZM mods - PZM Boomerang v1.1 (now with audio clip)
« on: February 05, 2006, 11:40:09 PM »
We used to use these mics a lot back in the analog days - suprisingly good sound from this mic - I think they were around 25 bucks new back then...the rising high-end worked nicely with cassette tech. I eventually beat my pair to shit - but - I just got another pair - I'm going to try to mod this set to the hilt...I appreciate any ideas...!

First step was to get rid of the stock metal plates. They ring and and are bit small. A bigger plexiglass plate also tames the high end a bit - pushes the peak a bit further up in the spectrum. I decided 8x8x1/4 was enough improvement without making this rig too huge.

The new 8x8 plates are mounted to a piece of aluminum angle material. The angle material is notched and to create a shallow V. Each plate is roughly 10 degrees from parellel. Just enough to imply some directionality.

TO DO:

Next - Upgrade power supply. Open the battery case and locate the battery treminal wiring. Solder a 9V snap on where the existing leads connect to the board. The manual reccomends using two PX23 6v batteries stacked on top of each other to increase high SPL handling - they are a bit hard to get - so we settled on 9v snap ons...I may untimately set this to use the same 9v batteries used in the Nakamichi/Primo mics...

I'd like to move the battery pack/power supply closer to the capsule. It is my understanding that the  signal is balanced post battery box (even though its comes stock 1/4 unbalanced) - - - but there is 20 feet of flimsy unbalanced cable between the capsule and the power supply. Id like to reverse that. Move the power supply so it lives just behind the plexi plate - with an XLR out - so I can connect with a standard mic cable - and get rid of anything dangling from the mic.
« Last Edit: February 17, 2006, 08:52:34 AM by Roving Sign »

Offline poorlyconditioned

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #1 on: February 05, 2006, 11:59:04 PM »
We used to use these mics a lot back in the analog days - suprisingly good sound from this mic - I think they were around 25 bucks new back then...the rising high-end worked nicely with cassette tech. I eventually beat my pair to shit - but - I just got another pair - I'm going to try to mod this set to the hilt...I appreciate any ideas...!

First step was to get rid of the stock metal plates. They ring and and are bit small. A bigger plexiglass plate also tames the high end a bit - pushes the peak a bit further up in the spectrum. I decided 8x8x1/4 was enough improvement without making this rig too huge.

The new 8x8 plates are mounted to a piece of aluminum angle material. The angle material is notched and to create a shallow V. Each plate is roughly 10 degrees from parellel. Just enough to imply some directionality.

TO DO:

Next - Upgrade power supply. Open the battery case and locate the battery treminal wiring. Solder a 9V snap on where the existing leads connect to the board. The manual reccomends using two PX23 6v batteries stacked on top of each other to increase high SPL handling - they are a bit hard to get - so we settled on 9v snap ons...I may untimately set this to use the same 9v batteries used in the Nakamichi/Primo mics...

I'd like to move the battery pack/power supply closer to the capsule. It is my understanding that the  signal is balanced post battery box (even though its comes stock 1/4 unbalanced) - - - but there is 20 feet of flimsy unbalanced cable between the capsule and the power supply. Id like to reverse that. Move the power supply so it lives just behind the plexi plate - with an XLR out - so I can connect with a standard mic cable - and get rid of anything dangling from the mic.

+T for the hacking.

You might want to do a search on "PZM mods" or similar.  If you haven't done so already, you should also visit the Yahoo group "micbuilders".  The main thing you want to do is wire the electret in three-wire "source follower" mode.  And the other thing is to remove the 'lytic caps.  Basically all you want is the equivalent of a three-wire battery box (:)) there, none of the original circuitry.  As far as balanced/unbalanced I wouldn't worry about it if you can get your preamp within ten feet of the stand.

Good luck, and keep us informed.

  Richard
Mics: Sennheiser MKE2002 (dummy head), Studio Projects C4, AT825 (unmodded), AT822 franken mic (x2), AT853(hc,c,sc,o), Senn. MKE2, Senn MKE40, Shure MX183/5, CA Cards, homebrew Panasonic and Transsound capsules.
Pre/ADC: Presonus Firepod & Firebox, DMIC20(x2), UA5(poorly-modded, AD8620+AD8512opamps), VX440
Recorders: Edirol R4, R09, IBM X24 laptop, NJB3(x2), HiMD(x2), MD(1).
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Roving Sign

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #2 on: February 06, 2006, 12:16:56 AM »
Cool - I've definitely researched a bit - looks like Rick Chinns mod is the most developed  - and he makes a nice kit.

http://www.uneeda-audio.com/pzm/

But maybe a little over the top - not sure it matters to me to run them off phantom

I'll sign in at the Yahoo group, thanks!

Offline darkmeevish

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #3 on: February 06, 2006, 11:08:42 AM »


i've been using my pair of pzms (the 33-1090b models) since around '96.  i've been very happy with them in small clubs.  no, they're not neumanns (how's that for an understatement), but for the investment they've been great.

i really like that aluminum angle bracket. i've only recently begun to think about rigging up a stand for mine, and that looks like a great idea.

currently, i've got mine mounted to 15" squares of plexi, which i can either hang (from the ceiling) close to the stage, mount on poles (with zip ties) near the stage, or tape to walls near the stacks.  i've also built little stands (to basicially hold the plate upright) that i might run from the lip of the stage, but i haven't tried that setup yet. 

besides getting a stand that would hopefully make setting up easier, i have been considering some of the mods that you've found floating about.  however, while i do know a soldering iron from a turkey baster, i am not about to try to mod my mics myself.

a couple of questions:

1) how do i find someone that could mod them for me? (i think i'm especially interested in xlr connections--in some clubs, i have to have quite a bit of distance between the mics and my r1. in fact, i have to use an extension cable in some instances.)

2) the original instruction manual recommended running a strip of material (i think they suggested a folded piece of carpet) along the bottom of the plate to limit the amount of unwanted noise (audience chatter) coming from below the mics.  i've never really tried that, but i've wondered if i could take it even a step further--would strips of acoustic foam (say, an inch or two thick) run along the edges of the plates improve the directionality of the mics? again, my goal here is to limit audience chatter.

oh, and i find the PX23 batteries at my local radio shack, no problem.  i don't think i've ever used any other batteries in them.

thanks for the info!

-mmd-


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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #4 on: February 06, 2006, 08:08:23 PM »
I had a pair of those RS PZM's that I used onstage in clubs. I still have one of them. I modded the connectors from 1/4" to XLR.
They made very good recordings too.

One of the best recordings I made was taping them to a big window outside in an apartment I had in the mountains. Of course I don't know where that tape is... But, they created a very convincing nature recording. I used to love recording thunderstorms with them too.
Reality is merely an illusion, albeit a very persistent one.

Microphones: AKG C 480 B comb-ULS/ CK 61/ CK 63, Sennheiser MKE 2 elements,  Audix M1290-o, Micro capsule active cables w/ Naiant PFA's, Naiant MSH-1O, Naiant AKG Active cables, Church CA-11 (cardioid), (1) Nady SCM-1000 (mod)
Pre-amps: Naiant littlebox, Naiant littlekit v2.0, BM2p+ Edirol UA-5, Church STC-9000
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Offline neutrino

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #5 on: February 06, 2006, 08:40:11 PM »
+T for the awesome job with the PZM's. I modded a pair myself which I ran in the early nineties but never got around to mounting them on plexiglass. They do clean up nice when you get rid of the noisy transformer and wire in some quality cable. Give us a sound sample when you get the chance...
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Offline darkmeevish

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #6 on: February 07, 2006, 10:34:24 PM »
well, as mentioned, i have not modded my pzms at all.  however, if you want to check out a kaki king show, i just posted this in kickdown central:

http://bt.etree.org/details.php?id=22515

unfortunately, it's mono--one of my mics did not get properly turned on (it obviously wasn't looking at kaki, heh)--but still i'm rather pleased.

i also still have a spam allstars show seeded over at etree, but it's getting rather slow (http://bt.etree.org/details.php?id=22287)

i would love any comments or guidance...

-mmd-
« Last Edit: February 08, 2006, 12:08:48 AM by darkmeevish »

Roving Sign

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #7 on: February 07, 2006, 11:00:25 PM »
I've actually just seeded a few things I recorded with PZMs

Sting - 6-26-93 opening for Dead - RFK
http://www.dimeadozen.org/torrents-details.php?id=77670

Grateful Dead 6-21-93 Deer Creek
http://bt.etree.org/details.php?id=21713

Phish 7-1-94 Philadelphia, PA
http://bt.etree.org/details.php?id=21676

Looks like the Creek torrent is still rolling - and i have Deer Creek - 6-23-93 on my harddrive, nearly ready to seed

There were all done with the stock plates - using the 2 PX23 batteries. No other mods. I used to tape the mics together in the middle - and I forget really - but - I had some sort of shim - and taped the whole thing to the stand. More or less in the same V angle as my new setup. Used the D5 mic pre into the D7.

Here's a little mp3 snippet of the Deer Creek show (about 7MB)

http://www.therovingsign.com/pzmsample.mp3
« Last Edit: February 07, 2006, 11:17:48 PM by Roving Sign »

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #8 on: February 07, 2006, 11:51:30 PM »
wow roving sign, they sound much better than i thought they would at a dead show. makes me wish i had tried that back in the day.

i really am debating putting money into modding mine rather than trying to upgrade to an entry level pair of something else.  i just need to figure out which upgrades to do and how much they would cost.  and as mentioned, i'd need to find someone who could to do the labor.

thanks--

mark

edited when i realized that outside is a REALLY big room
« Last Edit: February 07, 2006, 11:56:20 PM by darkmeevish »

Roving Sign

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #9 on: February 08, 2006, 12:29:03 AM »
Well - actually owning a pair of working mics is most of the investment!

They are regularly bringing around $40-50 a piece on ebay...

Im trying to track down some panel mount XLRs - I'll grab a few off ebay if cant get any locally tomorrow...

I'll stick with the stock circuitry for now - but just move it closer to the mic...shorten the long cable - make so I can use any mic cable.

Getting the basic balanced mod done should be easy and cheap - the cost of two XLR jacks and someone to solder.

This page has some info too - another stab at phantom powering...this makes it sound a little easier.

http://www.celestial.com.au/~rosswood/data/images/PZM%20Mod.PDF

Roving Sign

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Re: Realistic PZM mods - homebrew stereo wing - NOW v1.1
« Reply #10 on: February 15, 2006, 09:03:38 PM »
Ok - I did some modding to the PZM set...

Basically - I moved the power supply closer to the mic element. This eliminated about 20 ft of unbalanced wire.
They are set up to run off 9v snap on batteries.
The power supply circuit board and battery are both in the box on the back of the mic.
For now - you have to open the cases to turn the mics on and off. - I just unsnap them although the switch is still on the board.
« Last Edit: February 15, 2006, 09:05:45 PM by Roving Sign »

Roving Sign

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Re: Realistic PZM mods - PZM Boomerang v1.1
« Reply #11 on: February 16, 2006, 01:24:03 AM »
Here's a sample of the new setup - just me playing a little low D - although the low D on this guitar was a bit plunky...

http://www.therovingsign.com/pzm01.flac (7MB)

BTW - I've renamed this project "PZM Boomerang" - because of the shape...and - In memory of an old black fellow named Percy Reid who used to run with the hippies in the Northern WVA and South Central, PA area. He lived to be 87 and could still party with the young boys latenight right up to the end. He was a teacher (spiritually), and one of the most amazing people I've ever met. One of his most famous sayings was "Boomerang" - which he would say anytime someone pitched him a comment or expressed afffection. It meant "right back at you" - Which is somewhat appropriate for this kind of mic...!
« Last Edit: February 18, 2006, 04:08:12 PM by Roving Sign »

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Re: Realistic PZM mods - PZM Boomerang v1.1 (now with audio clip)
« Reply #12 on: March 07, 2006, 07:09:37 PM »
Nice job on the PZM mods.  I am a fan of PZMs, I used them for live sound stage micing some hard to mic drums in several bands I played in for 15 years.  Very clean sound, smooth bass, no phasing effect at all. I am working on some mods similar to yours.  It looks like you mounted yours centered on the plates, you might want to try lowering them to 2.5 inches off center for better sound, see this official crown site for details on why: http://www.crownaudio.com/pdf/mics/127089.pdf, page 12 and 17.

It says for flattest response place the PZM 1/3 of the way off center (4" for a 2' panel).  Lots of other fun things to try also.

If you really want to soup up those old Radio Shack PZM, check out http://www.uneeda-audio.com/pzm/ I just got 2 of his mod kits and will be trying them out to increase dynamic range, and lower noise, and phantom power.  Those PZM are the best $30 mics by far, but you need to know how to use them and I like your rig.  I want to try to make the angle between my plates adjustable.
AT853 (CMC-4)>3wire batt.box or SP box >Edirol R-09 or iRiver H120 or JB3
C4 > D-mod UA-5 >Edirol R-09 or iRiver H120 or JB3

Roving Sign

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Re: Realistic PZM mods - PZM Boomerang v1.1 (now with audio clip)
« Reply #13 on: March 08, 2006, 12:47:54 AM »
Oooo good...I was hoping to find someone who has the Chinn boxes.  I saw those - but decided to take a more incremental approach...just for fun. But obviously, he has the most refined design. I'm definitely interested in hearing how the kit assembly goes.

Thanks for the Crown links - I'll check that out - I am going to build a second "wing" eventually. Probably should consider some of that info.

I've used PZMs a good bit - I forget how we came up with that design - but I think we found the closer the mics got together the less difference there was in channels - kicking them out a bit seemed to help create bit more stereo feel.

For long spreads we just had a flat bar - better to keep them in the same plane once they get more than a foot apart.

I havent gotten to use this particular rig yet - once I do I will post some samples...

Offline NJFunk

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Re: Realistic PZM mods - homebrew stereo wing v1.0
« Reply #14 on: March 09, 2006, 01:05:32 PM »
I've actually just seeded a few things I recorded with PZMs

Sting - 6-26-93 opening for Dead - RFK
http://www.dimeadozen.org/torrents-details.php?id=77670



Holy Crap!!!  Sorry to thread-hijack, but this set was a seminal moment in my life.  Sting's set was miles better than the Dead show this night (the Dead carried the energy through Stranger, but it faded after that and the 2nd set was boring as hell).

Let me clear some things up.  What you have is in fact the first night with the Walking On The Moon jam only from the second night.  A Day In The Life was played the first night.  The second night, Sting played a smokin', Smokin, SMOKIN' Penny Lane.  Don Henley played only during the second night.  Do you have a complete copy of the 26th?  I would love, love, love to hear that again.

I remember being all totally tripped out with my girlfriend at the time dancing hard on a nearly empty green to Penny Lane and then watching in amazement at the Walking On The Moon with Jerry and then Don Henley (I wasn't sure if I hallucinated Don Henley until someone confirmed it for me).  That set is seriously one of the best memories of my entire life.  We were stoked for a revival of the legendary 73 era RFK shows from the Dead, or even just the 90-91 quality would have sufficed, but that turned into a big letdown.

 

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