Microphone Ground Loop Problem

Vocaroo | Voice message
I missed this sound sample because it didn't have the usual format - but this is extremely useful.
It is NOT a grounding issue, because ground loops are always loud and low (50 or 60Hz) plus a little of the harmonics. This is a high frequency that has data on it - you can hear it. It's coming from the processors, and is generated by the computer internally. It shouldn't of course, be on the audio, but many external and internal audio interfaces handle this very badly, and sometimes it's because of grounding issues, but mostly just poor design of more than one component that on their own, work just about acceptably, but when combined - all hell breaks loose!

The solution is a proper microphone, a proper interface and a computer with a motherboard that people have had success using for audio. Once all these good bits are in place - success is usually guaranteed.
 
Thanks for all the replies everyone, I can't tag everyone so I'll just reply here.

From what I've seen i think its the problem of a bad sound card and I should try to plug the microphone into my laptop without sound card and use it by reducing the external mic volume. By the way, its just as Dave said, its very hard to predict as most of these mic works for the people that i have researched with no problem. (1)So If i were to plug the mic directly w/o sound card, which i did, my laptop doesn't register my microphone, how can i make my laptop detect it?

Note: my laptop has only 1 3.5mm port that acts as the headset output and will have to act as a microphone input as well in this case. Just stating to see if it has any influence.

This is given that im not getting a phantom power source first. (2)And could the problem be solved if i get a phantom power source?
 
fingerdance said:
Thanks for all the replies everyone, I can't tag everyone so I'll just reply here.

From what I've seen i think its the problem of a bad sound card and I should try to plug the microphone into my laptop without sound card and use it by reducing the external mic volume. By the way, its just as Dave said, its very hard to predict as most of these mic works for the people that i have researched with no problem. (1)So If i were to plug the mic directly w/o sound card, which i did, my laptop doesn't register my microphone, how can i make my laptop detect it?

Note: my laptop has only 1 3.5mm port that acts as the headset output and will have to act as a microphone input as well in this case. Just stating to see if it has any influence.

This is given that im not getting a phantom power source first. (2)And could the problem be solved if i get a phantom power source?
Click to expand...

Ah, I think the technical term for your situation there is, you're stuffed!
I have not got/never had a laptop or PC that did not have two (at least) 3.5mm jacks on them. I dare say it would be possible to make or even buy an adaptor (be '3.5mm 4 pole split to 3.5mm 3 pole X 2) but likely cost as much as the mic!

Go and bother the ass off a shop and see if the mic will work with an XLR-XLR cable* into a mixer with phantom power (see 'our' Maplins for shop styles). If it does consider a modest USB interface, taking on board my caveats!

*Tell them you will buy the cable, you will need one anyway.
Dave.
 
fingerdance said:
This is given that im not getting a phantom power source first. (2)And could the problem be solved if i get a phantom power source?
Click to expand...

Use a real interface that has a mic preamp.
I decided to get one of these and its a 48V phantom powered mic. Yes its possible that some could operate at lower voltages, but its not going to sound good because its under powering the buffer circuit.
 
ecc83 said:
I have not got/never had a laptop or PC that did not have two (at least) 3.5mm jacks on them.
Click to expand...

I just bought a HP Laptop 45 days ago and all it had was the headphone out jack. Most everyone is going with the USB Headsets and believe it or not, I had to pay extra to have a R/W CD Rom installed as well.
 
drtechno said:
Use a real interface that has a mic preamp.
I decided to get one of these and its a 48V phantom powered mic. Yes its possible that some could operate at lower voltages, but its not going to sound good because its under powering the buffer circuit.
Click to expand...

I intend to get another one of these mics and I shall tear it apart and check but I suspect the Z converter power is stabilized by a zener so phantom power will make no difference to the supply voltage.

Dave.
 
gianluca68 said:
For the headphones/mic socket, you can buy a headphones/mic splitter for computers.
Click to expand...

Indeed: StarTech.com Headset adapter for headsets with separate headphone / microphone plugs - 3.5mm 4 position to 2x 3 position 3.5mm M/F: Amazon.co.uk: Computers & Accessories

But there is no guarantee it will work and in any case OP will still be going through the laptops $1 grotty soundcard!

If he is in the least serious about recording he should invest in an AI and an XLR cable.

Dave.
 
gianluca68 said:
For a cheap price, it would be better a Behringer or a Samson USB microphone.
Click to expand...

You might think so but my quick tests with a BM-800 showed it to have a better noise performance (via 3.5mm jack) than a £60 Maplin USB mic.

Almost all USB mics are 16 bit and at the mercy of Windows generic USB drivers. Both these things are ok for podding but if people are wanting good quality and a low noise floor for music or VO they need to spend the Wonga on an AI and a better microphone.

Dave.
 
ecc83 said:
Ah, I think the technical term for your situation there is, you're stuffed!
I have not got/never had a laptop or PC that did not have two (at least) 3.5mm jacks on them. I dare say it would be possible to make or even buy an adaptor (be '3.5mm 4 pole split to 3.5mm 3 pole X 2) but likely cost as much as the mic!

Go and bother the ass off a shop and see if the mic will work with an XLR-XLR cable* into a mixer with phantom power (see 'our' Maplins for shop styles). If it does consider a modest USB interface, taking on board my caveats!

*Tell them you will buy the cable, you will need one anyway.
Dave.
Click to expand...

So what you are saying is basically get a XLR-XLR cable and a phantom power source?
I see...
 
fingerdance said:
So what you are saying is basically get a XLR-XLR cable and a phantom power source?
I see...
Click to expand...

I just re-read your entire post and if you could, can you explain it is you want to record? If it is for Podcasting, you may be able to get fair results or maybe not, depending on your recording environment. If it is for music, your set up just doesn't meet the criteria. You are already fighting an up hill battle by having to use your 1/8 th mic input.

You need to realize that every step you use in audio, will degrade it slightly. What that means is your mic is plugged into an xlr to 1/8 inch cable. That cable is plugged into your cable adapter needed due to your laptop only having one 1/8 inch input, that cable is now plugged into your computer. That = 6 steps. Now combine that with, and there is really no other way to say it and I mean no disrespect, a cheap mic.

Now combine that with your audio having to go through a sound card, that is not sold to be used on a "Professional Level" for recording and combine that with windows does not supply the power needed to power your mic, and if it does, it will not be what is referred to as clean gain. You can start to see why you may be having these issues once you combine all these things together.

If you can afford to, you may want to look into something like a ATR 2100. You can plug it into your USB and I think they are around $79.00s new. You can also pick up used ones for 30 to 40 bucks, but it is really not a good idea to do so, unless it is from a music store that will give you some type of warranty. Just so you know, even this may not work depending on the specs of your laptop/sound card.

I know this is not what you want to hear, but sometimes it needs to be said so you don't spend weeks trying to solve a problem that has no solution, as well as wasted money, going down the rabbit hole.
 
I just got a PM and I'm bringing it out onto the thread for all to benefit from my reply:

Forum User PM's me:
"Hey, you seem to be pretty up to date concerning computer issues. My questions is this. If you use a condenser mic run into a phantom power supply and than into the 1/8th jack on the computer, does any of the voltage needed to power the condenser come through the jack as well, or is it just the boosted signal?

I am asking as there are many opinions that say yes it does and just as many as say, no it does not. I have read enough of you post to feel like I can trust your advice. I know that in my experience, the only mic that ever sounded good was the old desk top mics back in the day when you could get a phone card for your computer.

Everyone I know that tries to run the new cheap mics using phantom power, all have the dreaded hiss or high noise floor. I was told that it was mostly due to the input jack as it is not designed to receive any external power. So when you raise the mic input level, you simply raise the static as well. That makes sense to me, but it is just my opinion. "
Click to expand...
Well a phantom power brick AKA phantom power supply will not pass DC to its output. 48V is only present at the input connection (that you connect the mic to)

There isn't any real noise generated excessively however, you guys need to keep in mind the microphone inputs on a computer are always unbalanced. So any referencing to ground or power is going to inject noise on the signal.

As far as getting around this issue, you could try not referencing the ground nor the 5V power of the computer. This is accomplished by taking the 3.5mm TRS plug (the reader refers to this as an 1/8" plug) and just use the tip and the sleeve, The tip of the connector would go to pin 2 of the XLR and the Sleeve connects to pin 3 of the xlr. This removes the 5V that is present on the ring out of the circuit, and we isolate both grounds so there shouldn't be any noise injection Tom-foolery going on anymore.

Just to let you know, most of the microphones that were packaged with telcom cards were dynamic mics. (that is why they were t-s)
 
fingerdance said:
So what you are saying is basically get a XLR-XLR cable and a phantom power source?
I see...
Click to expand...

No*, What I am saying is, get the mic tested on a known good device, probably a mixer that has phantom power and buy an XLR mic cable. IF the mic delivers clean sounds THEN look at buying a basic Audio Interface. Faffing about with a 48V power supply and the crap jack input is a waste of time and money. The phantom supply will cost $20-$30 and that's 1/3rd to 1/2 way to an Alesis i02! If you can find a S/H i02 you will probably get it for almost $30!

At the risk of repeating myself (old, meds y'know) DO NOT buy one of the bog S single mic input AIs. You WILL regret it.

*(with nods to Mack's & DrT's posts)

Dave.
 
One of the problems I see in using a computer's mic power is that its not always on the ring too, and on standard 48V phantom microphones, they don't always pick up the phantom voltage on pin 3. So this is why the brick power supply. But a standard interface that has a standard mic preamp is going to give you a better connection because it is designed for these microphones (because its balanced ,which will be the lowest noise operation) and will properly power the microphone.


Using the microphone jack is a poor choice because of its unbalanced connection as well as the jack itself is not standardized (sometimes power is on tip, others on ring).
 
@drteckno, thanks Brother. I booked marked your answer and I am sure it will be something to the effect of "Just go read this written by drtechno, we need to start there and I am 99.9% sure that is your problem".

Maybe we can get @jimmys69 or another mod to make your answer sticky in the proper forum or maybe you could even do a write up on the issue if you had time. With the recent flood of these mics, and I mean they are popping up all across the www in other audio communities from podcasting to narration, your answer could be applied to all.

Great explanation!
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