could blow a mic here ahhh (help advice please)

J

jimbo.jams

New member
Hey all,
well kind of exited home studio sorted . stand for two mics , stand for h4npro NOW THE PROBLEM , i have a bullet condenser mic in input one and my shure sm58 into input 2 ,, now i knew i needed phantom power for my bullet mic ,, sat down with me guitar , had a final read only to find out you cant have phantom power just to one input ,, ive read it goes to both only ?? wow could have damaged my sm58 ,, i dont get this how they missed this in the design , being such a good tool ,,, OR AM I WRONG and can you separate ,
thankyou in advance for help jim:mad::guitar:
 
Once plugged in, phantom power will not harm a dynamic mic. However, it is advisable to connect/disconnect with the phantom off.
 
Like said above, phantom won't hurt a dynamic mic.

What do you mean by bullet mic? A Shure "green bullet" is a crystal mic which doesn't need phantom.
 
bouldersoundguy said:
Like said above, phantom won't hurt a dynamic mic.

What do you mean by bullet mic? A Shure "green bullet" is a crystal mic which doesn't need phantom.
Click to expand...

I am guessing JJ means the 'Silver Bullet' capacitor mics? They are a very low cost but well regarded microphone. I tried to buy a pair a day or two ago but they seem to have gorn.

Yes, phantom power is safe for all types of common microphones (maybe don't connect a 50yr old, $4000 ribbon? ) The only possible problem can be in the XLR cable if wires become disconnected/short. I urge ALL musos to buy a test meter and check cables a couple of times a year.

'Hot Pluggin' will cause loud bangs through the system and might damage cans or speakers but I have never seen a documented case. Don't do ears and nerves any good mind!

Dave.
 
I have a CAD drum kit that I bought some years back. I had two of the TSM411 mics go out at the same point. The only commonality was that I had plugged them into a recorder with phantom power on. I checked both with a multimeter and both showed as an open circuit on both capsules. I even wrote to CAD and asked if those mics were sensitive to phantom power and they replied that they should be fine. It may have been plugging in while the 48v was on that produced a surge. I'll never know. Never had a problem with my Sennheisers or Shure dynamic mics.

Luckily MF had them on a Stupid Deal of the Day for about $15 a pop, so I replaced them. I could never figure out any other reason why they would have fried. I still use them, but I am careful to put them on channels without power.
 
TalismanRich said:
I have a CAD drum kit that I bought some years back. I had two of the TSM411 mics go out at the same point. The only commonality was that I had plugged them into a recorder with phantom power on. I checked both with a multimeter and both showed as an open circuit on both capsules. I even wrote to CAD and asked if those mics were sensitive to phantom power and they replied that they should be fine. It may have been plugging in while the 48v was on that produced a surge. I'll never know. Never had a problem with my Sennheisers or Shure dynamic mics.

Luckily MF had them on a Stupid Deal of the Day for about $15 a pop, so I replaced them. I could never figure out any other reason why they would have fried. I still use them, but I am careful to put them on channels without power.
Click to expand...

I would say CAD were right and it was just a massive coincidence. I have a cheapo plastic mic here and I am going to put phantom power through the capsule. I shall parallel up pins 2 and 3 and apply the 48V to core and screen(it is wired unbalanced on single core)

My prediction is that there is NOT enough power from a spook juice source to burn out a mic coil.

"Oil be beck!" (maybe dripping egg!)

Dave.
 
ecc83 said:
...'Hot Pluggin' will cause loud bangs through the system and might damage cans or speakers but I have never seen a documented case. Don't do ears and nerves any good mind!

Dave.
Click to expand...

Wes Dooley of AEA warns that plugging/unplugging dynamics with phantom engaged risks magnetizing the transformer which will compromise performance. In addition, if your monitors are up loud enough, you can blow a driver.
 
RRuskin said:
Wes Dooley of AEA warns that plugging/unplugging dynamics with phantom engaged risks magnetizing the transformer which will compromise performance. In addition, if your monitors are up loud enough, you can blow a driver.
Click to expand...

I cannot see how you can magg up a transformer when no net current flows in said transformer? Unless of course you have a misswire as already stated.

The BBC's OB vans had 48V on ALL mic channels and NO switches or lights. They would not have done that if peeps had been buggering 4038s and Ball and Biscuits all over the shop!

Been out ('er feet y'know) bu will do test ASAP.

Dave.
 
ecc83 said:
I cannot see how you can magg up a transformer when no net current flows in said transformer? Unless of course you have a misswire as already stated.

The BBC's OB vans had 48V on ALL mic channels and NO switches or lights. They would not have done that if peeps had been buggering 4038s and Ball and Biscuits all over the shop!

Been out ('er feet y'know) bu will do test ASAP.

Dave.
Click to expand...

I'm operating under the assumption that it's better to be safe than sorry.
 
I have a question for you Dave. I did once have two HDD's die with full platter failure as well as a mobo. All at the same time. After, I bought a UPS to keep power in control.

I only assume that there was a power surge that killed my drives and mobo. Is it possible that a power surge could also change voltage to phantom power and cause this kind of mic destruction.

I ask because you are such an awesome geek when it comes to electronic issues. And I mean 'geek' in the best possible way. :)

Cheers!
 
RRuskin said:
I'm operating under the assumption that it's better to be safe than sorry.
Click to expand...
I remember years ago when I bought a Mackie mixer one of the cautions in the manual was to have phantom power off when plugging or unplugging cables because, if I remember correctly, the sudden surge (which we know happens because there wouldn't be a loud pop if it didn't) can, over time, damage the mic-pre.

Didn't say anything about mics though.
But since then I've always made sure it's off before plugging or unplugging.

Safe rather than sorry is also my motto ...... it's not like it's a difficult burden
 
jimmys69 said:
I have a question for you Dave. I did once have two HDD's die with full platter failure as well as a mobo. All at the same time. After, I bought a UPS to keep power in control.

I only assume that there was a power surge that killed my drives and mobo. Is it possible that a power surge could also change voltage to phantom power and cause this kind of mic destruction.

I ask because you are such an awesome geek when it comes to electronic issues. And I mean 'geek' in the best possible way. :)

Cheers!
Click to expand...

"Surging" phantom power? IMHO no. The 48V is derived in bus powered AIs from a DC-DC converter and are thus stepping UP 5 V from USB, bit more from the now virtually obsolete FussyWire so even if the converter 'punched thru' you cannot get more voltage. Then the amount of power, 'watts' is miniscule, if you dumped ALL the juice from an XLR socket into the right load of 3.4k you would get a smell over 169 milliwatts, most small signal transistors can handle 3 times that power level.

Five volts rms (abt +16dBu) can be had from many 'serious' headphone amps and the is nearly 800mW!

To answer the one about the HDD and MOBO going AWOL...Yes, likely your mains had a massive spike on it and somehow that elevated the 5V and 12V rails in the computer. Did the PSU fail as well?

I have seen a fair bit of lightning damage to TVs, VCRs and some audio and one factor is always the same? They are NEVER the same! Things you think are fragile survive and stuff you thought was of the BSH persuasion is a molten mess. That is for a direct or near direct strike of course but you get periferal secondary damage and that can be equally weird in what is clucked and what is not.

But then 'We' suffer few storms and get even less damage than other countries. I put this down to the very overengineered electrical system the robbing private bastards have inherited and the fact that most of our supply gets into the dwellings underground in armour, i.e. 'shielded'.

Dave (happy to be ANY sort of geek!)
 
"Mackie mixer one of the cautions in the manual was to have phantom power off when plugging or unplugging cables because, if I remember correctly, the sudden surge (which we know happens because there wouldn't be a loud pop if it didn't) can, over time, damage the mic-pre."

Then Mackie have gone down in my estimation. Sure, the charge/discharge of the coupling caps* in a mic pre's front end CAN cause damage to the following electronics but any decent engineer KNOWS that and puts in a couple of diodes to absorb the tiny pulse of current.

There are RULES to designing circuits.
#1, don't beat yourself up...see how the competition did it first.
#2 IF you care about giving the punyter a fair shake and reliable kit you have to assume SHIT'APPEN!

*Worth considering that even when Spook is turned to off those caps are still charged and take fekking AGES to drain away!
Manufacturers put in loads of ass saving ***t because they don't want to get sued. A typical example is the caveat that a valve guitar amp must ALWAYS have exactly the right value speaker load on it. In practice 50% either way is safe if the amp is half way decently made. People that drive the absolute tits off them night after night are going to fek'em anyway.

Dave.
 
ecc83 said:
"Surging" phantom power? IMHO no. The 48V is derived in bus powered AIs from a DC-DC converter and are thus stepping UP 5 V from USB, bit more from the now virtually obsolete FussyWire so even if the converter 'punched thru' you cannot get more voltage. Then the amount of power, 'watts' is miniscule, if you dumped ALL the juice from an XLR socket into the right load of 3.4k you would get a smell over 169 milliwatts, most small signal transistors can handle 3 times that power level.

Five volts rms (abt +16dBu) can be had from many 'serious' headphone amps and the is nearly 800mW!

To answer the one about the HDD and MOBO going AWOL...Yes, likely your mains had a massive spike on it and somehow that elevated the 5V and 12V rails in the computer. Did the PSU fail as well?

I have seen a fair bit of lightning damage to TVs, VCRs and some audio and one factor is always the same? They are NEVER the same! Things you think are fragile survive and stuff you thought was of the BSH persuasion is a molten mess. That is for a direct or near direct strike of course but you get periferal secondary damage and that can be equally weird in what is clucked and what is not.

But then 'We' suffer few storms and get even less damage than other countries. I put this down to the very overengineered electrical system the robbing private bastards have inherited and the fact that most of our supply gets into the dwellings underground in armour, i.e. 'shielded'.

Dave (happy to be ANY sort of geek!)
Click to expand...

I invested in the UPS after the failure. The power supply was fine. Just two 7200 1tb Seagate drives and soon after the MOBO failed. I don't remember the model # of the mobo. The power supply is still kicking as I am typing with that PC now. It is my internet computer. After that happened I built a new recording PC. And new interfaces as well since.

I was just curious if that sort of situation could also affect phantom power.
 
Ok. The Test!
Attached is a terrible, hummy recording but it at least proves the mic works. The mic is a Philips SBC MD150 with a plastic body and metal mesh similar to a '58. Unbalanced its DC resistance pre test was 758 Ohms (Fluke 83 DMM)

I used a Mk1 8i6* for the test as it has a 2A 12V supply and should deliver full spec spook. Actually measured 46V off load which is only 'jeee'ust' in spec!

I connected the mic coil across pin 2 and pin 1 and the phantom voltage collapsed, 0.002V. There should have been 4.55V across the mic coil so this turns out to be a somewhat abortive test becuase the F'rite obvioulsy current limits the phantom output, a good thing so long as it delivers enough!

Post test the mic cell still measured 758Ohms. N very B! Throughout these tests I was handling bare wires with 48V on them and twisting and shorting them like ans ape'***t b'std. At NO time did I recieve even the slightest tingle nor see any sparks!

I do NOT of course suggest in ANY way MY cavalier approach to electronics to the uninititated!

I don't use the AI very much but it is pretty good and stand a good comparison to my NI KA6 in terms of sound quality and mic pre performance. What was NOT evident during the couple of hours I worked with it was the stability and 'goodness' of the KA6's drivers!

*Several times the 8i6 locked up Sam SE8 or ProX Silver and it took a shut down and re plug of the USB cable to sort it out.
I have seen several threads on this and other forums about Focusrite instabilities. Never, AFAIK for the KA6.

All this was done on an old but servicable HP i3 laptop. W7, 8G ram 360G HDD about 1/2 filled. In the next day or so I shall try to get the F'rite working on my W10 Lenovo T510 and report back.

Bottom line on 48V...Be aware but don't worry too much.

(got to go out now but be back in about 2 i.e. 1pm GMT)

Dave.
 

Attachments

  • phil mic01.mp3
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I have NEVER followed the advice to kill the phantom because it's often meaning a long walk! Often the fader gets left up and there is a big crack. Been doing this since my first condenser in around 1979. never lost a studio monitor, although clearly the bang is disconcerting and something a fader drop takes care of. Sticking 48V up the spout of any microphone has never ever caused a problem, and like many others, phantom switching is in my view pointless - and on old analogue desks, the actual switch would make the application of the voltage swing wild, again often thought of as bad, as will plugging in an XLR connector - the voltage will always be applied to pin 2 or 3 first - and this never kills mics. Indeed, the only mic I ever saw die was an SM58 that was plugged into the dangling XLR, that had been mistakenly connected to the remote control socket for a cheap smoke machine. God knows why they used XLR-3 for the connector but they did - with 240V between pin 1 and 2!!!! It wasn't spectacular at all, just a kind of pop.

Fader down before connection = good move. Actual 48V turnoff? Unnecessary.
 
On the Tascam M-2600 Mk II that I use regularly my procedure is to switch the input from mic to line when making or breaking connections. That at least keeps the pop from getting into the system.
 
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