Running an unbalanced mic through a balanced XLR cable into a balanced input

SlowButEffectiv

New member
Hi. I'm a newbie so am posting here. I've checked the newbie FAQ and done a search and didn't find this, so my apologies if this has been asked before.

I have a Pyle PDMIC58 dynamic microphone, bought last month. This model used to be wired unbalanced (search youtube for "Pyle PDMIC58 Microphone - SM-58 Knockoff" without the quotes; I'm not allowed to post a link as I'm a first-time poster). However, at least one poster on another forum has said that it is now wired as balanced. I want to know for sure* without taking the mic apart (I'm not handy, and the screw is hard to turn--don't want to break it). So I ran the mic using a balanced XLR cable into my TASCAM US-4x4 interface using the IN1 XLR port. It worked, i.e. sound came out of the headphones, and the signal indicator lit.

My question: If the mic were wired as unbalanced, would I have heard anything on my headphones? (Which I did, see above). I would assume the answer is no, as wouldn't the two signals would be subtracted out from each other?

--Richard

*The reason I want to know for sure is I will also have a condenser mic using phantom power, and the TASCAM manual says "When using condenser mics that require phantom power and dynamic mics together, be sure to use balanced dynamic mics. Unbalanced dynamic mics cannot be used when phantom power is enabled" I'm worried I'll wreck something if the mic turns out to be unbalanced. I can't attach an image (first post), but if I did it would show that pin 1 and pin 3 are connected inside the mic, at least they were for the older instances of the PDMIC58. I mention this in case there are other ways to wire an unbalanced mic.
 
I am known a bit here for a hobby horse and that nag is Get a Bloody Meter!
With even the most basic, carshop digital meter you can check the mic. Look at the pins and they should be numbered. Put the meter on "Ohms" and connect to pins 2 &3. You should read a resistance that could be anything from about 150 to 600 Ohms. Now check 2 or 3 to pin 1, there should be no reading, i.e. infinity.
Lastly check pin 1 to the body of the mic, should read very low, short circuit.

I suspect the mic IS balanced otherwise you would get a hum. Even if the mic was Ubal' phantom power would likely do it little harm and even if it did you are only out a £20 mic!

Dave.
 
+1 on the meter. It will come in handy all over the place.

I'm not sure it's the mic we'd be worried about though. One would hope that the phantom source is current limited or otherwise protected against short conditions, but whether it would still be able to power the condenser while shorted is another question.
 
+1 on the meter. It will come in handy all over the place.

I'm not sure it's the mic we'd be worried about though. One would hope that the phantom source is current limited or otherwise protected against short conditions, but whether it would still be able to power the condenser while shorted is another question.

Phantom power is inherently currently limited from any reputable source. Pins 2&3 each have a 6k8 resistor in circuit so the maximum current that could flow is 7mA and the bus powered Tascam probably couldn't manage even that.

Yes, if the 48V was shorted on ONE XLR it might cause some loss on the other but I dare say the capacitor mic would still work, many modern ones will cope with 12 volts.

The only real danger with phantom power is if peeps connect the INPUT of some ad hoc gear to the XLR. Few devices are protected past supply rail voltages and that is 36V tops. There is the old saw about OLD ribbons, never read of an actual instance of damage but makes sense to keep $3000+ mics off spook juice since they don't need it!

Dave.
 
Thanks very much Dave. I checked and resistance across pins 2 & 3 was close to 600 (the nominal spec). Resistance from 2 to 1 was negligible (the multimeter would read 1 or 001 or -1). After I posted I had also taken apart the mic at the pins end and saw it was correctly wired as balanced, but it was nice to verify with the multimeter. The mic sounds great, no noise or anything. Looking forward to our next podcasting session!
 
Thanks very much Dave. I checked and resistance across pins 2 & 3 was close to 600 (the nominal spec). Resistance from 2 to 1 was negligible (the multimeter would read 1 or 001 or -1). After I posted I had also taken apart the mic at the pins end and saw it was correctly wired as balanced, but it was nice to verify with the multimeter. The mic sounds great, no noise or anything. Looking forward to our next podcasting session!

Cool! It is an annoying fact that there are a lot of cheap mics around* that use an XLR but wire it unbalanced (pin 3 to pin 1) and supply an XLR to TS jack cable. This is stupid since you obviously have to remove the XLR mic connector to convert it to balanced. They don't seem to understand that this can be done in the CABLE instead!

*Why buy uber cheap (like $10) mics? Well for instance I have a pair permanently setup in my garden and over the last 5 years or so they have lasted about 6 months on average (tho' the present incumbents have done best part of a year! On offer at £4.50 Maplin) ...I mean, I am NOT going to put Sm7bs out there am I?
There are other instances where mics must be regarded as 'disposable' (aka 'nickable') TB links in theatres, Trade shows, anything to do with kids...)

Dave.
 
I never turn phantom off - the only 'rule' I have is only connect with the fader down!

Balanced, unbalanced, dynamics and condensers - plug 'em in and use them. Often you may use a mic for ages and assume it's wired balanced because they all are - to discover one wasn't and you never noticed.

One thing to remember when the XLR connector won't come out of a mic is to check it doesn't have a reverse thread on the screw - you screw the wrong way!
 
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