can anyone think of what the point to this is

[pucho812]

looks like an re-20 dynamic element being fed a 4Vpp 10Hz sine wave well at least the scope shows the last numbers I am only guessing the re20 part.

https://www.youtube.com/watch?v=DQr-yJx-s1M&feature=youtu.be

What I am trying to figure out is why would anyone do such a thing?

 

[Gustav]

Too much Macallan "Fine Oak" Scotch?

Gustav

 

[pucho812]

I have no idea. It got posted somewhere else(not GS)  during a discussion on what phantom can do to a sm-57 dynamic capsule if the mic has had the transformer removed and is wired per the mod specs of + off the capsule to pin 2 and - off the capsule to pin1(ground).  If phantom were switched on it would send dc across the dynamic element. Will that damage it? I don't know. I have never researched it. But I do know wired as mentioned will produce 48VDC across the element.  Then someone posted that video and a debate ensued of weather or not with the transformer removed and wired as mention if the element will get damaged.

The signal in the video is AC thus the motoring. I would like to see that happen with a DC signal.

 

[Mendelt]

The guy does have a history of abusing RE-20s

http://youtu.be/i31styRC_VM
http://youtu.be/87kQI41wGcs

 

[warpie]

What I am trying to figure out is why would anyone do such a thing?

He's a GDIY member, isn't he?
Maybe he'll chime in...

 

[pucho812]

What I am trying to figure out is why would anyone do such a thing?

He's a GDIY member, isn't he?
Maybe he'll chime in...

Is he? hmmm interesting.

 

[Indecline]

what phantom can do to a sm-57 dynamic capsule if the mic has had the transformer removed and is wired per the mod specs of + off the capsule to pin 2 and - off the capsule to pin1(ground).  If phantom were switched on it would send dc across the dynamic element. Will that damage it?

Yes, phantom power will destroy a 57 with the transformer removed. Learned that the hard way  :-X

 

[LeeYoo]

When fixing/reconing woofers, I do center voicecoils that way.
When you feed a 10herz signal signal into them, you can instantly hear things like a rubbing voicecoil or buzzing pigtails.
No sure if that's wise with a dynamic microphone  .
But I do test dynamic mics on a headphones output, with music (low volume).
Listening to them, like headphones, instantly reveals buzzing/rubbing problems.
Leo..

 

[usekgb]

Ummm......  If you're going to remove the transformer from a '57, don't wire one side of the capsule to pin 1!  Ever!  Use pins 2 and 3 silly.  This will make it safe from phantom power, and still maintain the shielding.

 

[pucho812]

Ummm......  If you're going to remove the transformer from a '57, don't wire one side of the capsule to pin 1!  Ever!  Use pins 2 and 3 silly.  This will make it safe from phantom power, and still maintain the shielding.

Yeah and the tape op article says to wire it to pin 1 and pin 2

 

[Indecline]

Ummm......  If you're going to remove the transformer from a '57, don't wire one side of the capsule to pin 1!  Ever!  Use pins 2 and 3 silly.  This will make it safe from phantom power, and still maintain the shielding.

So it wasn't my fault after all  ;D

 

[gyraf]

Usually I put 1KHz at 200mV into the RE-20 when replacing diaphragme/voice-coil, to get it centered right. The frequency shown is too low, and amplitude is too large to make real sense to me.

The RE-20 is the only one of our studio's microphone collection that has required regular replacement of moving parts. It's probably not REALLY designed for living inside kickdrums...

Jakob E.

 

[usekgb]

Ummm......  If you're going to remove the transformer from a '57, don't wire one side of the capsule to pin 1!  Ever!  Use pins 2 and 3 silly.  This will make it safe from phantom power, and still maintain the shielding.

Yeah and the tape op article says to wire it to pin 1 and pin 2

Really?  I must have missed that when I did one years ago.  I just wired mine to 2 and 3.  It sounded pretty cool, but the output was really low.  Later, I installed one of the Rode active pre's (no longer available) and it ended up pretty cool.

 

[joaquins]

Ummm......  If you're going to remove the transformer from a '57, don't wire one side of the capsule to pin 1!  Ever!  Use pins 2 and 3 silly.  This will make it safe from phantom power, and still maintain the shielding.

Yeah and the tape op article says to wire it to pin 1 and pin 2

Really?  I must have missed that when I did one years ago.  I just wired mine to 2 and 3.  It sounded pretty cool, but the output was really low.  Later, I installed one of the Rode active pre's (no longer available) and it ended up pretty cool.

The output level is expected to be low, you just need a good preamp with tons of gain, well, tons if you are using it with low level sources, not so much gain using it on a snare or a guitar cab... Some people just replace the tx with a better one, TAB had ones which I've seen being use for this, I've also seen a video with the comparison of TAB, stock and transformer less, and it had a PT session or the tracks to download and hear the comparison in high quality in your DAW

JS

 

[usekgb]

Yeah.  I know about those TAB transformers.  Cinemag also makes the CM-1057.  At the price point of a stock '57 plus the upgrade transformer, I would rather save up a little more and get another SM7!

 

[Andy Peters]

Too much Macallan "Fine Oak" Scotch?

You mean too much Two Fingers tequila, methinks.

-a

 

[pucho812]

one tequila, two tequila, three tequila, floor.

 

[MicDaddy]

Here's DC (fire the camera man!  ) https://www.youtube.com/watch?v=KjzErgi3BLg&feature=youtu.be

~300mA+ only to show what extremes these coils can be put through for the discussion as was noted above.  The dc resistance of that coil is in tens of Ohms. 

I don't know the dc resistance or what #AWG the 57 coil is or material.  Maybe the diaphragm is not held onto the faceplate well enough and it jumps out of the magnet structure which then snaps a lead?  Maybe the 57 is an outlier that is susceptible to low currents say from phantom discharge due to a cable fault?  Suppose if the coil was < 10R @ #54AWG maybe it burns up? 

Not long ago I thought phantom WOULD kill a dynamic/coil mic..  tried and tried and someone over at the blue forum finally showed me the light.

6K81 resistors... being mostly naive to the electronics world I was completely ignorant to this current limitation.  Having done some calculations, maybe they're not correct, I don't believe the current present in a coil (due to a phantom power fault condition) would cause it to burn up.  My evidence is little formula, lot bit anecdotal.

Jakob is right in using AC for centering, it's a trick used for the D12.  I use different frequencies to observe several things. 

DC for a polarity check
AC for observations

The 10yr is nice, the 25yr is fantastic (but way above my pay grade)