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-   -   Vintage Dynamic Mic Ground Issue without DI (https://www.gearslutz.com/board/geekslutz-forum/1316977-vintage-dynamic-mic-ground-issue-without-di.html)

andersmv 1st July 2020 04:15 AM

Vintage Dynamic Mic Ground Issue without DI
 
2 Attachment(s)
I'll send this to my tech friend eventually, but he's swamped right now and I've got a few projects coming up where I'll actually use this mic. I've got an older Turner dynamic microphone from the 40s/50s, it actually has a cannon XLR connector. If I try to use it with a normal XLR cable, I get a huge grounding issue and really low output. In the meantime, I found I could use a Female XLR to TRS cable with it, run that into a DI and then go XLR out of that. No buzz or grounding issues, it's pretty quiet all things consider but needs a LOT of gain.

On a whim, I ordered one of those Whirlwind XLR ground lifter barrels (https://www.sweetwater.com/store/det...E&gclsrc=aw.ds) thinking that might fix the issue so I could bypass the DI. That didn't work, I don't think I got any signal at all when I tried that. Does anyone have any suggestions? Is this just a classic case of older mic designs switching two of the pins around? I'm sure I'll get it sorted eventually, but I'm curious to hear some advice in the mean time...

I've attached sound samples. One is a quick test through an XLR cable with more grounding problems when the mic is touched. The other one is the mic XLR-TRS going into a DI (Sorry for the hokey recording, I sent it to a friend as a joke because he was curious about the sound....)

elegentdrum 1st July 2020 04:19 AM

The mic is worn out. Low output. use a good preamp.

andersmv 1st July 2020 04:22 AM

Quote:

Originally Posted by elegentdrum (Post 14831862)
The mic is worn out. Low output. use a good preamp.

I just posted some sound samples. It's not a preamp issue.

jaddie 1st July 2020 08:04 AM

Quote:

Originally Posted by andersmv (Post 14831855)
Is this just a classic case of older mic designs switching two of the pins around?

Very likely because 1. The XLR was a relatively new connector in 1950, and wiring may not be standard and 2. Your symptoms demonstrate the mic is working but wired wrong.

The fix requires soldering. You up for that?

andersmv 1st July 2020 07:36 PM

I would rather not dig around inside the mic, hoping I could find a cable solution.

mbrebes 1st July 2020 07:45 PM

Do you have a multimeter? If you do, the first thing I would check is the grounds. Resistance should be 0 ohms between pin 1 and the XLR shell. Also both of those points should also measure zero to the outside metal casing of the microphone. Many of those old Turner mics are high impedance. Open the XLR and see how it is wired.

andersmv 1st July 2020 08:02 PM

Quote:

Originally Posted by mbrebes (Post 14833112)
Do you have a multimeter? If you do, the first thing I would check is the grounds. Resistance should be 0 ohms between pin 1 and the XLR shell. Also both of those points should also measure zero to the outside metal casing of the microphone. Many of those old Turner mics are high impedance. Open the XLR and see how it is wired.

That's the problem, I can't really get inside the mic without possibly damaging the capsule. It's a weird/rare model, so I'm going to trust my tech to do that eventually. I know I'm being annoying and making this more difficult than it should be, I was just curious for some insight in the mean time. I'll check all that with a multi meter. I do know the impedance is lower at 150, they included that on the model label.