Home |
Search |
Today's Posts |
#1
|
|||
|
|||
Phantom Power Filtering (removal of phantom power)...
Hey Everyone. I can't seem to find the answer and/or product to
satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Thanks, Chris |
#2
|
|||
|
|||
"Chris Breitner" wrote in message
m Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Measure the resistance from pin 2 and 3 to pin 1 using an ohm meter with limited current, such as a good DVM.. If it is infinity, you don't have a problem, and then stop worrying. |
#3
|
|||
|
|||
"Chris Breitner" wrote in message m... Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Two options : 1:1 Isolation Transformer - The better Transformers usually cost more and it is not difficult to spend $100 on a decent Transformer ... Capacitors in Series with the Signal - 47uF is usually adequate but can depend on the input impedance of your mixing desk - typically 1K or so which will give you low Frequency rolloff with a -3dB point of 3Hz Of course the Desks internal Decoupling Caps will be in Series with this so this will probably raise your -3dB point to 7 Hz or so. D Pin 2 ---------------||--------------- Pin 2 of the Mic e +ve s Pin 3 ---------------||--------------- Pin 3 of the Mic k Pin 1 ------------------------------ Pin 1 of the Mic Arent Ribbon Mics a bit delicate to take on the road ??? Regards Richard Freeman |
#4
|
|||
|
|||
"Arny Krueger" wrote in message ... "Chris Breitner" wrote in message m Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Measure the resistance from pin 2 and 3 to pin 1 using an ohm meter with limited current, such as a good DVM.. If it is infinity, you don't have a problem, and then stop worrying. Of course it could have a Transformer isolated output in which case he could read a near short and still not have to worry .... |
#5
|
|||
|
|||
|
#6
|
|||
|
|||
Chris Breitner wrote: Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Thanks, Chris If its your board, go into one of the channels and remove the two phantom resistors from the channel you want to use the ribbon on. It will just cost you some time (if you know what your doing that is) Otherwise, a good isolation transformer as some else suggested externally Bob -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 100,000 Newsgroups - 19 Different Servers! =----- |
#7
|
|||
|
|||
Chris Breitner wrote:
Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Someone will, I hope, correct me if I'm wrong, but couldn't you just lift the ground and go with a floating ground? The potential is between pin 1 (the ground) and pin 2 and between pin 1 (the ground) and pin 3. There is no potential between pins 2 and 3 because there are equal value resistors between them and the +48V of the phantom power. I'm assuming, of course, that cutting the ground near the mic will still provide you with adequate noise shielding, etc. - Logan |
#8
|
|||
|
|||
"Richard Freeman" .. "Arny Krueger" "Chris Breitner" I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Measure the resistance from pin 2 and 3 to pin 1 using an ohm meter with limited current, such as a good DVM.. If it is infinity, you don't have a problem, and then stop worrying. Of course it could have a Transformer isolated output in which case he could read a near short and still not have to worry .... ** You better **re-read** what Arny posted - ie test from pins " 2 and 3 to pin 1 " !!!!!!! .................... Phil |
#9
|
|||
|
|||
"Chris Breitner" wrote ...
Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? It might help to actually reveal the make/model of your microphone. It may be one that tolerates phantom power just fine without any mucking about. Especially if it is a newer one that presumably survives life on the road. (?) |
#10
|
|||
|
|||
"Logan Shaw" Someone will, I hope, correct me if I'm wrong, but couldn't you just lift the ground and go with a floating ground? The potential is between pin 1 (the ground) and pin 2 and between pin 1 (the ground) and pin 3. There is no potential between pins 2 and 3 because there are equal value resistors between them and the +48V of the phantom power. I'm assuming, of course, that cutting the ground near the mic will still provide you with adequate noise shielding, etc. ** Why don't you try out your own idea and check your assumption ??? ............... Phil |
#11
|
|||
|
|||
"philicorda" wrote in message news On Wed, 30 Jun 2004 17:44:19 -0700, Chris Breitner wrote: Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Thanks, Chris You could use a battery phantom power supply box for this. It may sound silly, but if it's off and has no batteries in it, it should just block the dc and pass the mic signal. You should check with a meter, just to make sure. But if it uses polarized capacitors (quite likely), they will be facing in the wrong direction. |
#12
|
|||
|
|||
Phil Allison wrote:
"Richard Freeman" .. "Arny Krueger" "Chris Breitner" I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Measure the resistance from pin 2 and 3 to pin 1 using an ohm meter with limited current, such as a good DVM.. If it is infinity, you don't have a problem, and then stop worrying. Of course it could have a Transformer isolated output in which case he could read a near short and still not have to worry .... ** You better **re-read** what Arny posted - ie test from pins " 2 and 3 to pin 1 " !!!!!!! Never heard of a centre-tapped transformer as often used in what would now be vintage gear ? Nice DC R connecting all the pins. Had a real problem once ( thankfully a long time ago ) when given some gear to set up for a 'society event' with CT balanced outputs that had to be connected to unbalanced inputs. I'll leave you to guess which way the cables were wired. Thankfully I was able to troubleshoot it on the spot. The hired DJ ( a well known radio celebrity ) had kittens quietly while I fixed it. Needless to say, I wasn't best pleased. Thank goodness these days for floating balanced outputs. Graham |
#13
|
|||
|
|||
"Pooh Bear" wrote in message ... Phil Allison wrote: "Richard Freeman" .. "Arny Krueger" "Chris Breitner" I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Measure the resistance from pin 2 and 3 to pin 1 using an ohm meter with limited current, such as a good DVM.. If it is infinity, you don't have a problem, and then stop worrying. Of course it could have a Transformer isolated output in which case he could read a near short and still not have to worry .... ** You better **re-read** what Arny posted - ie test from pins " 2 and 3 to pin 1 " !!!!!!! Never heard of a centre-tapped transformer as often used in what would now be vintage gear ? Nice DC R connecting all the pins. ** Got any idea at all why the ohm meter tests are being suggested at all ????????????? It would **really ** help if you pulled your fat head out of your bum prior to posting, Pooh. ................. Phil |
#14
|
|||
|
|||
On Wed, 30 Jun 2004 17:44:19 -0700, Chris Breitner wrote:
Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Thanks, Chris You could use a battery phantom power supply box for this. It may sound silly, but if it's off and has no batteries in it, it should just block the dc and pass the mic signal. You should check with a meter, just to make sure. |
#15
|
|||
|
|||
One possibility I didn't see presented is a separate mic pre for the ribbon,
which then goes into the line in rather than through the mic input. There are a couple of "buy it now" Studio Projects VTB1s on ebay right now for $129. Not an un-useful purchase anyway, and it easily fits your requirements. http://cgi.ebay.com/ws/eBayISAPI.dll...38307 79&rd=1 -- Roger W. Norman SirMusic Studio "Chris Breitner" wrote in message m... Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Thanks, Chris |
#16
|
|||
|
|||
Hey Everyone. I can't seem to find the answer and/or product to
satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? Blocking caps will remove DC, but that won't do anything for the thump when you power it on. A transformer will remove DC, but again you need to plug it into the power supply first, then plug the mike into it, because it doesn't do anything about the thump from an imbalanced phantom supply. And, unless it's an RCA mike with a center tap that hasn't been lifted, the power-on-thump from a badly built phantom supply with mismatched resistors is the only problem. What is this mike, anyway? If it's an M-500, don't worry about it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#17
|
|||
|
|||
"Logan Shaw"
Someone will, I hope, correct me if I'm wrong, but couldn't you just lift the ground and go with a floating ground? The potential is between pin 1 (the ground) and pin 2 and between pin 1 (the ground) and pin 3. There is no potential between pins 2 and 3 because there are equal value resistors between them and the +48V of the phantom power. When this is actually the case, there's no problem at all using phantom power with a ribbon. The reason it can be a problem (aside from mikes with center ground taps on the transformer secondary) is that sometimes those resistors are not very equal values. I'm not going to mention any particular brand of mixers, but suffice it to say that some of the cheaper ones out there don't match the supply resistors very well. This also badly degrades common mode rejection as well as making for an issue with dynamic mikes. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#18
|
|||
|
|||
|
#20
|
|||
|
|||
Richard Freeman wrote:
Arent Ribbon Mics a bit delicate to take on the road ??? No, the ribbon mikes I own are plenty rugged. Besides, people bring their violin on the road, don't they? And their girlfriend? My BK-5's are less delicate than my girlfriend by a wide margarine. ulysses |
#21
|
|||
|
|||
Chris Breitner wrote:
Hey Everyone. I can't seem to find the answer and/or product to satisfy my needs: a phantom power filter/remover. I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. Does anyone know of a DIY homebrew solution? You've gotten plenty of good advice so far, but the one thing barely mentioned is that besides a center-tapped output transformer, a defective microphone cable is just about required in order for phantom power to damage a ribbon mike. So buy yourself a nice $25 mike cable that's a different color than all your other mike cable. Treat it gingerly and label it "only for XXX ribbon mike." Don't let anybody step on it, tug on it, tie it in knots, or run it over with a rack full of heavy equipment. This will cost a heck of a lot less than a good isolation transformer. ulysses |
#22
|
|||
|
|||
In this place, Justin Ulysses Morse was recorded saying ...
My BK-5's are less delicate than my girlfriend by a wide margarine. .... and the prize for quote of the week goes to ... ulysses LOL! (BTW - just how wide IS a margarine?) -- George Newcastle, England Problems worthy of attack Prove their worth, by hitting back [Piet Hein] |
#23
|
|||
|
|||
George Perfect wrote:
In this place, Justin Ulysses Morse was recorded saying ... My BK-5's are less delicate than my girlfriend by a wide margarine. (BTW - just how wide IS a margarine?) From what I understand, margarine is really fat. - Logan |
#24
|
|||
|
|||
Logan Shaw wrote:
From what I understand, margarine is really fat. Petroleum-based artificial fat, at that. |
#25
|
|||
|
|||
Don't mean to be argurmentative, but I have never, ever seen any RCA ribbon mic with a grounded
center tap(including 44A's, PB90's & all the way back). What IS grounded is one end of the primary side of the transformer, because the mic frame is generally used as the return path for one end of the ribbon. This is not a problem for phantom, however. What damages the ribbon, as has been mentioned, is the thump created by unbalanced feed resistors, and also by poor quality cables or connectors. No ribbon mic, other than those with active electronics, are truly "phantom safe". It's just some mics are more sensitive to phantom thumps than others. This has to do with factors like the turns ratio of the mic's transformer, ribbon size, thickness & corrugation type, and magnet strength. Basically, the more efficient that a ribbon mic acts as a speaker, the more prone to phantom damage it will be. And I have personally seen stock Beyer ribbons damaged by phantom. -- Stephen Sank, Owner & Ribbon Mic Restorer Talking Dog Transducer Company http://stephensank.com 5517 Carmelita Drive N.E. Albuquerque, New Mexico [87111] 505-332-0336 Auth. Nakamichi & McIntosh servicer Payments preferred through Paypal.com "Mike Rivers" wrote in message news:znr1088681345k@trad... In article writes: I have a ribbon mic I'd like to gig with, and the PA systems we use normally plug into have an all-channels-on/off for the phantom power. Our vocalist uses a condenser mic, so she needs it on. If the phantom power hits my ribbon mic, it might permanently damage the ribbon element. The factoid that a ribbon mic will be permanently damaged by phantom power is true if the microphone has an internal transformer with a grounded center tap. Older RCA ribbon mics (the Model 44 for sure, perhaps others of the era) had this arrangement because they found that in some cases, it reduced hum pickup. Unless you got an RCA 44 from a collector, chances are any 44 that you'll find now will have that center tap lifted and the mic is not at risk as long as you don't connect it with a cable that's shorted between the shield and one of the conductors. This is the reason for the suggestion that you check for conductivity between pin 1 and each of the other two pins. If it's near a short circuit, there's probably a center tapped transformer. If it's near an open circuit (a few megohms, typically) then your mic is safe. Modern ribbon mics such as those from Beyer and Royer are all "phantom safe" (I have no idea about the modern Russian mics) but it's still a good idea not to hot-plug them, but to connect all the mics and then turn on the phantom power. It's good to be concerned, but the solution may be simpler than you think. Of the proposed solutions, I'd go for the isolation transformer or capacitors rather than fussing with an outboard power supply for the condenser mic. Some day you might have two condenser mics, or five, and will have to solve the problem all over again. -- I'm really Mike Rivers ) However, until the spam goes away or Hell freezes over, lots of IP addresses are blocked from this system. If you e-mail me and it bounces, use your secret decoder ring and reach me he double-m-eleven-double-zero at yahoo |
#26
|
|||
|
|||
Scott Dorsey wrote: The reason it can be a problem (aside from mikes with center ground taps on the transformer secondary) is that sometimes those resistors are not very equal values. How does this cause a problem (other than the rejection issue)? If the same supply is presented to each side, and 1 is open, then current won't flow between 2 and 3 regardless of the mismatch. Bob -- "Things should be described as simply as possible, but no simpler." A. Einstein |
#27
|
|||
|
|||
|
#28
|
|||
|
|||
Bob Cain wrote:
Scott Dorsey wrote: The reason it can be a problem (aside from mikes with center ground taps on the transformer secondary) is that sometimes those resistors are not very equal values. How does this cause a problem (other than the rejection issue)? If the same supply is presented to each side, and 1 is open, then current won't flow between 2 and 3 regardless of the mismatch. I didn't word that very well at all. If there _are_ center ground taps, there is a ground path to pin 1, and therefore the imbalance is an issue. In fact, even with the ground tap, if there are precise enough resistors and a good enough transformer, it's a non-issue. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Power Filtration | Audio Opinions | |||
Power conditioner or power cord or something else | Audio Opinions | |||
Phantom Power Filtering (removal of phantom power)... | Tech | |||
rec.audio.car FAQ (Part 1/5) | Car Audio | |||
Can you run Phantom Power to non-condenser mics? | Pro Audio |