Connecting a XLR mic to a Computer

Thomaswb

New member
Hey Everyone. Just thought i'd see if anyone here could help me out with this problem i've come to.

I picked up a cheap vintage XLR sony cardio ecm-21n electeret condenser, and found it is powered by 1 AA battery, so i pulled it apart, cleaned it all up, sanded the battery contacts, and then bought a XLR to 3.5 mm jack adapter off ebay.

I figured even though it's XLR, it is battery powered, so i wont need a preamp/DAC.

When i connected it up and recorded in audition, the recording levels are stupidly low, hitting the front of the mic only raises the meter a few DB from background noise.

I foresee some questions, here, i'll answer a few before they are asked:

Yes, the battery is brand new and installed in the correct direction.

The mic was plugged into the Mic port on my desktop, not the line-in.

I configured the levels so it's 100% volume in settings.

And i tested it on another computer and it is the same.

I even tested it on a external sound blaster, it didn't help.

So i would really appreciate if anyone can shed some light on this situation.

Any help much appreciated! :)

Thanks.
- Thomas.
 
Electret capsules can lose their polarisation after years and become very low output. Could be yours has, although I have several Sony's of comparable vintage that still work well.

And when you say "cleaned up", was there any moisture involved? Electrets don't like moisture of any kind.
 
Electret capsules can lose their polarisation after years and become very low output. Could be yours has, although I have several Sony's of comparable vintage that still work well.

And when you say "cleaned up", was there any moisture involved? Electrets don't like moisture of any kind.

Thanks Cyrano, oh thats a shame. Should the way i set it up work though?

And no, it was perfectly dry, it just had a foam part in the top that had degraded into dust, and fell into the tube battery compartment, and some of the battery holder contacts had become corroded slightly.

I guess it's not fixable?

Also, is it a good mic? i couldn't find any info on it online.
 
Don't lose hope just yet. I suspect it's more likely to be a mismatch between the mic and the input. The sound card input is not designed for the balanced signal produced by the mic. The usual solution is to get a proper audio interface with an XLR mic input. It's possible that a different version of the XLR-3.5mm cable may work, but an audio interface is more certain to solve the problem.

Do you know anyone with a small mixer? There has to be some other way to test the mic.

Does the 3.5mm end of the adapter look like a stereo headphone plug (three metal contacts, two plastic insulators), or does it have only one plastic insulator separating only two metal contacts?
 
Don't lose hope just yet. I suspect it's more likely to be a mismatch between the mic and the input. The sound card input is not designed for the balanced signal produced by the mic. The usual solution is to get a proper audio interface with an XLR mic input. It's possible that a different version of the XLR-3.5mm cable may work, but an audio interface is more certain to solve the problem.

Do you know anyone with a small mixer? There has to be some other way to test the mic.

Does the 3.5mm end of the adapter look like a stereo headphone plug (three metal contacts, two plastic insulators), or does it have only one plastic insulator separating only two metal contacts?

Yes... i researched balanced mic's but i figured using a adapter would just treat it as a unbalanced mic. well, yeah, I've been avoiding getting a external DAC for now. I've just started out recording some piano, and i have a behringer c-1u, and got this mic and figured i could get stereo with both. And no, as i'm a beginner i don't know any other people who could help me out :/

It is a stereo jack (TRS).
 
I'd guess the capsule has lost the charge - after all it's 40 years old! Something in my memory says these were switchable impedance too - high unbalanced and low balanced that was done from inside? It's possible the previous owner had it wired for high impedance, which could be reversed. I could be talking rubbish - but I'm sure this range of mics was switchable?

p.s. Don't spend any money - these mics when new were pretty nasty sounding things. They certainly were not classic recording mics.
 
Yes it does seem that way. I'll research about the wiring setting thing and see if there is anything to that, thanks.

We'll I'm not complaining, I got it almost for free from a op-shop.
 
I'd be very much surprised if this was a balanced output. The kind of capsules in the ECM range is unbalanced to start with. And just putting an XLR on it doesn't make it balanced.
 
"And just putting an XLR on it doesn't make it balanced. "

As I am always informing people thusly C! Last resort, put the mic somewhere warm and very dry for 24 hours. A heated airing cupboard is ideal but no clothes! That MIGHT dry it out and make it work but I doubt it.

Getting a 1/2 decent recording of a piano is challenge enough! Don't start with ***t kit!

(as ever, look at the NI KA6)

Dave.
 
I'd be very much surprised if this was a balanced output. The kind of capsules in the ECM range is unbalanced to start with. And just putting an XLR on it doesn't make it balanced.
Evidently 'balanced'. Found and old Sony Video Equipment catalog with this mic. It notes having 3 different choices for impedance which I wonder how that is selected(?) Maybe the 'pigtail' provided the wires to select impedance(?)

I've built some cable adapters to go from XLR to 3.5mm TS, but this one from HOSA is likely what is needed for this mic. XLR pins 1 & 3 are bridged with pin 2 hot
Microphone Cable - Hosa Technology - XVM-305F

Kind of iffy whether the computers mic input has enough gain for this mic.
 

Attachments

  • ecm21n.jpg
    ecm21n.jpg
    185.4 KB · Views: 22
Last edited:
I'm amazed the memory was half good - I expected a high Z option, but the low impedance is a surprise. I can remember PA kit back then having very low impedance - I was using Grampian DP4 mics (still have one somewhere), and they were balanced 25Ohm systems.
 
I'm amazed the memory was half good - I expected a high Z option, but the low impedance is a surprise. I can remember PA kit back then having very low impedance - I was using Grampian DP4 mics (still have one somewhere), and they were balanced 25Ohm systems.

Ah! The DP4 http://www.xaudia.com/xmanuals/Grampian_wiring.pdf

Beloved of bingo callers when they weren't gobbing into a Reslo RB ribbon! Invariably they used the high Z 50K model* but the above shows the mic was available in 25, 200 and 600 Ohm variants.

It was also the classic reporters mic as the 600R version especially was more sensitive than most other mics of the time and the portable tape machines had pretty indifferent pre amps.

* Driving very often a Linear Concord 50W valve amplifier and a 12inch PA speaker in a "box baffle". The coming of the Japanese mics and cheap Silicon transistor amps saw the demise of theses rigs.

Dave.
 
I'd be very much surprised if this was a balanced output. The kind of capsules in the ECM range is unbalanced to start with. And just putting an XLR on it doesn't make it balanced.

But you still have to get the right XLR pins to the right 3.5mm pins. A given XLR-3.5mm adapter isn't guaranteed to work with every XLR mic and every 3.5mm input, while a proper interface is much more likely to work. Either way, the first thing to do (before spending money) is to try the mic on something with a known working XLR mic input.
 
Evidently 'balanced'. Found and old Sony Video Equipment catalog with this mic. It notes having 3 different choices for impedance which I wonder how that is selected(?) Maybe the 'pigtail' provided the wires to select impedance(?)

Well waddayoukno. That's a first. Thanks for looking that up. Not easy to find info 'bout these mics.

Is there a transformer or was Sony using a different capsule in this model?

Kind of iffy whether the computers mic input has enough gain for this mic.

Yep. At these numbers, that's THE question. It would require a good hi-gain preamp.
 
Wow there are so many people getting in on this, Thanks guys!

Too many to reply to separately now, but seems like the problem might be that it is set to high impedance currently. I researched briefly online and found that the signal strength of high impedance mics drop of very quickly when on a long cable. And the cable on mine is about 6 meters long! (EDIT: it cant be the case, according to that catalogue for the mic the max impedance is 600 ohms, with is still considered low impedance).

And thanks arcaxis! That image is very useful. It looks exactly like that, and it is the 21n, but it doesn't have a pigtail connector (whatever that is?), it has a cannon. Now, i just need to work out how to switch it, and if it is the case.
 
Last edited:
"And just putting an XLR on it doesn't make it balanced. "

As I am always informing people thusly C! Last resort, put the mic somewhere warm and very dry for 24 hours. A heated airing cupboard is ideal but no clothes! That MIGHT dry it out and make it work but I doubt it.

Getting a 1/2 decent recording of a piano is challenge enough! Don't start with ***t kit!

(as ever, look at the NI KA6)

Dave.


Could heating the Mic help even if it wasn't, and never appeared to be damp? I disassembled it all the way down to the capsule, everything looks fine.
 
But you still have to get the right XLR pins to the right 3.5mm pins. A given XLR-3.5mm adapter isn't guaranteed to work with every XLR mic and every 3.5mm input, while a proper interface is much more likely to work. Either way, the first thing to do (before spending money) is to try the mic on something with a known working XLR mic input.

But it seems to me, that if any signal is received by the computer at all (and it is, albeit quiet), then the adapter is working, and the problem is with the mic. Or is that flawed reasoning?
 
Back
Top