Connecting a XLR mic to a Computer

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?

If the 3.5mm input has stereo contacts but sums the tip and ring, you might get something like what the OP described with any good mic.
 
"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)."

Peeps do get their underwear in a tangle over matters of 'impedance'! Context is all: in microphone parlance, 'low' would certainly be anything at or under 600Ohms, tho' you did have very low Z mics of 30R, even 15! The attenuation due to cable is really only of concern for mics designated 'high' impedance and that means around 50k that were used by the early bands because EVERYTHING went into one valve amp with unbalanced, fairly low sensitivity jacks. (N.B. 'High' Z for valve amps means 1,000,000 Ohms, the 'Magic Meg')

The attenuation is however caused by cable capacitance and increases with frequency. Most mic companies suggested a maximum cable length of around 18feet for a response to about 15kHz. You would need 50mtrs or more cable on a 600R mic to make any appreciable droop in the HF response. Of course, those old 50k mics were unbalanced so as well as HF loss, longer cable could worsen hum pickup. (and the CB nutters of the era!)

Dave.
 
If the 3.5mm input has stereo contacts but sums the tip and ring, you might get something like what the OP described with any good mic.

Auctually yes, that makes sense. I'll chop the jack off the adapter and solder it to another stereo jack to make sure the tip and ring are separate. Thanks! I'll let you guys know if that worked when I do it - for future reference.
 
Auctually yes, that makes sense. I'll chop the jack off the adapter and solder it to another stereo jack to make sure the tip and ring are separate. Thanks! I'll let you guys know if that worked when I do it - for future reference.

Nope, not that way.

If your going to chop and solder you want to use a TS type plug that's wired sort of like below. You'll want to tie the wires together that come from pin 1 & 3 of the XLR together and solder those to the sleeve connection of the 3.5mm plug and pin 2 to the tip. This creates an unbalanced mono connection to the mic input on your computer.
Alternatively if you don't have a TS plug handy, bridge the ring and sleeve connections together on the 3.5mm TRS plug and connect pin 1 & 3 wires from the XLR there. If you need me to sketch that up I can.

In most computers the ring connection of the jack may provide a low bias voltage for cheap electret mics that do not have a battery like the mic you have. That connection is not intended to carry audio signal from a plug that has a ring connection of a TRS plug.
 

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Auctually yes, that makes sense. I'll chop the jack off the adapter and solder it to another stereo jack to make sure the tip and ring are separate. Thanks! I'll let you guys know if that worked when I do it - for future reference.

It's the computer sound card mic input that might have the tip and ring connected, in order to accommodate stereo sources going into a mono input without losing one channel. The tip and ring of your adapter are probably not shorted together. Half a minute with a DMM could confirm that.

Arcaxis' suggestion might work.
 
Nope, not that way.

If your going to chop and solder you want to use a TS type plug that's wired sort of like below. You'll want to tie the wires together that come from pin 1 & 3 of the XLR together and solder those to the sleeve connection of the 3.5mm plug and pin 2 to the tip. This creates an unbalanced mono connection to the mic input on your computer.
Alternatively if you don't have a TS plug handy, bridge the ring and sleeve connections together on the 3.5mm TRS plug and connect pin 1 & 3 wires from the XLR there. If you need me to sketch that up I can.

In most computers the ring connection of the jack may provide a low bias voltage for cheap electret mics that do not have a battery like the mic you have. That connection is not intended to carry audio signal from a plug that has a ring connection of a TRS plug.


Well Thomas clearly didn't think that one through! Luckily there are smart people like you and others here willing to help him :p.

Thanks Arcaxis! That makes sense, I should have a ts somewhere here, I'll do what you described, thanks for the sketch too!

Thanks guys, I really appreciate the help a lot! :)
 
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This rather sums up why any computer with a 3.5mm stereo input needs experimenting with because it has to cope with all kinds of I out bodges. So ground to the sleeve is standard, but feeding the signal to tip, no ring or ring no tip, or tip and ring combined may all work and produce I out on one channel or both channels. For what it's worth, I discovered one of my computers needs tip and ring being commoner for a mono input, while another on the same cable has a strange hollow sound, which is because one of the channels is the opposite polarity, which results in one of the pair of audio channels it creates being inverted, which of course partially cancels in mono!

Clearly, the often quoted opinion that computer sound card inputs are generally rubbish is spot on!
 
This rather sums up why any computer with a 3.5mm stereo input needs experimenting with because it has to cope with all kinds of I out bodges. So ground to the sleeve is standard, but feeding the signal to tip, no ring or ring no tip, or tip and ring combined may all work and produce I out on one channel or both channels. For what it's worth, I discovered one of my computers needs tip and ring being commoner for a mono input, while another on the same cable has a strange hollow sound, which is because one of the channels is the opposite polarity, which results in one of the pair of audio channels it creates being inverted, which of course partially cancels in mono!

Clearly, the often quoted opinion that computer sound card inputs are generally rubbish is spot on!

The other thing that may throw a curve is a laptop which may have a combo mic/headset input jack that takes a TRRS type of plug.
 
It worked Arcaxis! Since the adapter already had a trs on it, i just re-soldered the wires how you said, and bridged the ring and sleeve connections. It's not awesome quality, but it works!

Thanks very much everyone, this has been a very helpful and productive thread!
 
Good to hear it works a bit better. I have an old Sony stereo electret mic that is of a similar vintage as the one you have that was intended to be used with tape recorders. Like your mic, mine is 'not awesome quality, but it works' :).
 
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