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does anyone know how I can make a omni-dynamic mic into a PZM?


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Hello All!

 

Here is an interesting topic (I hope)... I read somewhere that an ordinary omni direcrional dynamic can be made into a PZM. Does anyone know how I could do this?

 

Better yet, does anyone have a pair of the Radio Shack PZM's they would sell to me pretty cheap?

 

any ideas?

 

-greg

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Originally posted by method_of_control:

Hello All!

 

Here is an interesting topic (I hope)... I read somewhere that an ordinary omni direcrional dynamic can be made into a PZM. Does anyone know how I could do this?

 

First, what microphone is it?

OMNI DYNAMICS are VERY rare...are you sure yours

is really omni?

 

 

Better yet, does anyone have a pair of the Radio Shack PZM's they would sell to me pretty cheap?[/b]

 

Radioshack would be cheap! http://www.musicplayer.com/ubb/biggrin.gif

Maybe someone has some they are not using??

 

What are you trying to do?

Valky

www.vsoundinc.com

Valkyrie Sound:

http://www.vsoundinc.com

Now at TSUTAYA USA:

http://www.tsutayausa.com

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Hey guys...

 

I may have been wrong that it was an omni dynamic. My impression was that it could be done with a 58.

 

As far as what I am trying to record, I am trying to slap together a demo recording of my friends band quick and dirty. I have virtually no good equipment right now, and am not looking to buy anything until I have enough money to by my paris rig and some decent mics.

 

So, here is my plan for ghetto recording:

 

come up with a pair of PZM's... record drums, guitar and bass live, into my computer in stereo via a small mixer. Then we will overdub second guitar, and the vocals. Reverb/EQ and compress...

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First, a 58 is not omni, it's cardioid, in pattern.

 

Second, to simulate a PZM, you could put the 58 up against a flat surface (say a wall) facing the surface. Unfortunately, this won't really sound like a PZM, nor will it utilize the advantages of a PZM.

 

To make a 58 sound like a PZM, sell the 58... buy a PZM! http://www.musicplayer.com/ubb/biggrin.gif

 

A PZM uses a tiny condenser mic placed V-E-R-Y close to a plate. This forces ALL sound waves to rebound off the plate in order to hit the diaphragm of the element. Because of this all the reflections are well in phase. There is no "direct" sound to the element to interfere with the rebounds. (Technically, vice-versa) The RS PZM's were built by Crown (they couldn't call them PZM's otherwise. patents.) but used a low voltage power supply. If you can get someone to up the power supply from 1.5v to 9v, the mic will perform like a (then new) $300 Crown. (The RS PZM's sold for $49 when they still carried them.)

 

------------------

Neil

 

Reality: A few moments of lucidity surrounded by insanity.

It's easiest to find me on Facebook. Neil Bergman

 

Soundclick

fntstcsnd

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Hi Emile,

 

Here's what I have:

 

1 beta 58

1 beta 57

1 seinheiser (not sure which... my friend has it) it sounded great for guitar last time I used it.

more 58's than you can shake a stick at

some tom mics

an akg bass drum mic

 

a behringer mixer... 8 channel, 4 pre, 4 line

8 channel powered mixer, 8 pre's

 

That is it!

 

So, what can we do here?

 

THANKS!

 

Greg

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Originally posted by method_of_control:

Hi Emile,

 

Here's what I have:

 

1 beta 58

1 beta 57

1 seinheiser (not sure which... my friend has it) it sounded great for guitar last time I used it.

more 58's than you can shake a stick at

some tom mics

an akg bass drum mic

 

a behringer mixer... 8 channel, 4 pre, 4 line

8 channel powered mixer, 8 pre's

 

That is it!

 

So, what can we do here?

 

THANKS!

 

Greg

 

Commit gear-icide!

 

(Stop it, stop it.... repeat after me, I won't be a gear snob, I won't be a gear snob...)

 

Actually, you have some decent mics. With those alone, you can do PLENTY. As to immitating a PZM, well.. it's not gonna happen. But if I were you, I'd attach a cardioid mic (preferably an SM57, as opposed to a '58 or the hyper cardioid Beta's.) to a 3 or 4ft. square panel with the mic pointed at the flat surface. Place it very close to the panel. A wire hanger can be used as a mount (somehow connected to the panel) or you can place the panel and then use a boom mic stand to place the mic. This will provide as much of a PZM's design as can be done without.. a PZM. Let us know how it sounds. I've always wanted to try this, but never took the time.

 

Remember, bass response will change with the size of your panel. PZM's are usually mounted to a larger panel, or to the inside of a piano top, using it as the panel.

 

------------------

Neil

 

Reality: A few moments of lucidity surrounded by insanity.

It's easiest to find me on Facebook. Neil Bergman

 

Soundclick

fntstcsnd

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FantasticSound - will that power supply push to 9 volts work on the last version of the Radio Shack "Boundary" microphone with the circular screen? I have a pair and suddenly see them useful for overhead to a live stage deal I'm doing in a few weeks...

 

Method... good luck on your recording.

 

"It's all about the... um-m-m, uh-h-h..."

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Originally posted by AudioMaverick:

FantasticSound - will that power supply push to 9 volts work on the last version of the Radio Shack "Boundary" microphone with the circular screen? I have a pair and suddenly see them useful for overhead to a live stage deal I'm doing in a few weeks...

 

Method... good luck on your recording.

 

I only know of someone modding the RS (Crown) PZM (square plate) that they sold for $49. I know they have carried boundary mics (not PZM's) since phasing out the Crown. I don't know what brand is behind the RS nameplate, and I'm not well versed in electronic circuitry. I know a professor at Columbia College, in Chicago used to do the mod. I'll try and get his name or schematics from my old college buddies.

 

Ask someone else to comment. Try picking Hiraga's brain. He and some of the other posters here and in GM's forum have a world of electronic and audio knowledge, and seem very willing to share it.

 

 

------------------

Neil

 

Reality: A few moments of lucidity surrounded by insanity.

It's easiest to find me on Facebook. Neil Bergman

 

Soundclick

fntstcsnd

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Although Radio Shack no longer carries the Crown Licensed PZMs you can still find them on eBay.

 

It is very simple to convert them into a mic with professional grade specs. Cut off the quarter inch plug and you will find three wires. Solder the shield wire to pin one of a male XLR plug. Solder the light colored wire to pin two and the dark colored wire to pin 3. The output of the mic is now balanced.

 

To increase headroom and s/n specs replace the single AA battery with two six volt camera batteries. (There is a model of six volt battery that is exactly half the length of a AA and two of them fit nicely end to end in the battery compartment.)

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FYI the batteries in question are Duracell 28A a.k.a. PX28A, A544, 4LR44. You COULD make a PZM with a lavalier mic mounted about 3/64" fom a metal plate - but I'd try ebay.

Scott

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Originally posted by Dr Hillbilly:

Although Radio Shack no longer carries the Crown Licensed PZMs you can still find them on eBay.

 

It is very simple to convert them into a mic with professional grade specs. Cut off the quarter inch plug and you will find three wires. Solder the shield wire to pin one of a male XLR plug. Solder the light colored wire to pin two and the dark colored wire to pin 3. The output of the mic is now balanced.

 

To increase headroom and s/n specs replace the single AA battery with two six volt camera batteries. (There is a model of six volt battery that is exactly half the length of a AA and two of them fit nicely end to end in the battery compartment.)

 

 

 

Can anyone else comment on whether increasing the voltage without altering anything else will yield better S/N or possibly damage the microphone. I mean, with all due respect, I could easily have made this switch, or wired in a 9v holder if that's all that is necessary for the switch. The guy who told me about it was handy with an iron, too! He'd had some modded.

 

 

 

------------------

Neil

 

Reality: A few moments of lucidity surrounded by insanity.

It's easiest to find me on Facebook. Neil Bergman

 

Soundclick

fntstcsnd

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I can state from experience that increasing the voltage works.It was covered in E.M. about a dozen years ago (also the tip about them being balanced out) as well as a mod for the electronics. Craig might know where to find the article. Mr. Anderton?
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I have six of these mics that have been in service for years with the described mods with no problems. I don't think you need to be concerned with injuring the mic, in fact, Radio Shack actually suggests within the owners manual swapping the AA for two six volt batteries. One suggestion: always remove the batteries between sessions. Even with the switch off, you will experience battery drainage with the increased voltage.

 

There are a plethora of RS PZM mods documented on the Web, ranging from physically modifying the electret capsule to adding phantom power. The increased voltage and balanced operation mods are by far the safest, easiest and (in my opinion) the biggest bang for the buck.

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