mono recording sounds terrible, stereo sounds good

[tolworthy]

When recording from a microphone, mono sounds awful - muffled and distorted. but stereo sounds fine. Has anyone else found this problem?

System details:
Audacity 2.2.1,
Windows 10 32 bit,
Tried on two different physical mikes. Tried both the "aux in" 3.5mm jack on my speakers and the similar one at the back of the computer.
I had the problem n an older version of Audacity, so I uninstalled it and got the latest version. Same problem.
The computer reports the microphone input as being "Connexant HD audio", and under "properties" I think everything is either default or a reasonable setting, but it is possible that I maybe changed some Windows setting months ago. If I did I don't remember it!

[DVDdoug]

Tried on two different physical mikes.

Exactly what mics? Are those "computer mics" or stage/studio mics?

Tried both the "aux in" 3.5mm jack on my speakers and the similar one at the back of the computer.

You should plug-into "mic-in". An Aux-in is line-level. It's not a mic input. And, I assume the one on your speakers goes directly to the speakers, bypassing the computer.

[kozikowski]

Do the microphones have this kind of connection on the bottom?



If so, the cable or interface between that and the computer is causing the problem. That kind of microphone naturally produces two different sounds that don't mix well and there is no convenient, simple, cheap way to get it into a computer.

I use a Behringer UM2 interface. It's simple, cheap, works well and it's certified for musical overdubbing if you're using it for music.

Screen Shot 2018-01-09 at 09.59.29.png (51.06 KiB) Viewed 229 times

That's it on the left.



Koz

[tolworthy]

Thanks for the detailed reply! The first mike is in a headset designed for computers, the second is a studio type mike (both are pictured). BTW, this isn't a problem now that I know about it: I can easily record in stereo, then convert to mono later. But it was frustrating for the couple of days when I couldn't work out what was wrong.

[kozikowski]

I can easily record in stereo, then convert to mono later.

By either splitting, flipping one side over (Effect > Invert) and adding; or deleting one side, right?

As you found, you can't simply jam Left and Right together.

That kind of microphone is desirable in long cable runs. Done with a good XLR interface, there is effectively no limit to the length of the cable. 100 foot mic runs are common. Compare that to the USB and consumer grade microphones with about a four foot limit.

Koz

[DVDdoug]

The first mike is in a headset designed for computers

That should work as long as you have the correct connection. Sometimes they have separate connectors for the headphones & mic, and sometimes there is a combination 4-conductor TRRS connector. If the connections on the computer & headset don't match, you need an adapter cable.

the second is a studio type mike (both are pictured).

Stage/studio mics are not compatible with regular consumer soundcards or the mic input on a laptop, and computer mics are not compatible with mixers, PA systems, or mic preamps, or USB audio interfaces.

Stage/studio mics have a balanced (3-wire) low impedance connection. The two signal wires are out-of-phase, which helps to cancel noise/hum pick-up.* The differential input on the mic preamp amplifies the difference signal and kills the common signal (which is noise-only). The mic input on a computer is not a differential amplifier and it's not designed for stage/studio mics.

If you use an adapter and split one signal to the left and the other to the right, they will be out-of-phase. If you just kill one channel and make mono, you might get acceptable results. If you combine those two signals together to make mono, everything cancels. If you listen to the out-of-phase stereo you'll get some "phase weirdness" as some of the sound waves mix and cancel in the air.

Studio condenser mics also require 48V phantom power (supplied by the preamp, mixer, or interface). A computer can only supply 5V for an electret condenser mic. Dynamic mics (like the famous Shure SM57/58) don't require any power. There are some stage electret condenser mics with an internal battery.

I'm pretty sure you have an electret condenser mic that designed to look and work like a studio mic. (I don't know if it can work properly from 5V.) A real studio condenser mic usually costs $100 USD or more.


* It's only for electrical noise pickup... The balanced connection doesn't help if your dog starts barking in the middle of your recording session.

[tolworthy]

Thanks for all the insights. Much appreciated! So could I summarise the advice as:

1. this is not some bug in Audacity, it's that real life engineering is fundamentally complicated
2. .,.which is why serious audio users pay serious money for multiple pieces of kit
3. ... and why cheap equipment is only designed to do certain things out of the box (e.g. stereo not mono)

Just to clarify, as you probably guessed, when I said "studio mike" I was speaking from ignorance. I just meant that it had the studio type cable, and was better than the ridiculously cheap mikes used in headsets. As far as I can tell they are extremely good for the price I paid (about £10 and £20), but of course not suitable for professional work.

[kozikowski]

#3 is more complicated than that. It doesn't work in stereo, either. Out of Phase stereo can sound like the performer is standing behind you rather than in front and as you noted, if you supply a production to a client, there's a chance it's going to fail for "magic" reasons, like the client is listening in mono. There's an industrial version of that, too. Supply a production to five clients and two of them fail for no known reason.

Out of phase stereo shows drive the speakers in small laptops and iPads nuts. Some of them use phasing tricks to appear larger than they really are.

That 1/8" socket on the sides of laptops has progressed over the years from full stereo but no microphone on Mac machines and mono microphone but no stereo on Windows machines to a Frankenstein monster of bad stereo and headset connection with low volume that doesn't do anything particularly well, but machine makers can claim it does.

And all those sockets look and fit exactly the same.

It's scary.

Koz