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."

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."

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."

"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."

"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."

"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."

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

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

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

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

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

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

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]

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]

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]

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

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

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

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

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

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

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."

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."

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."