Hey Unitron,

Sorry for the late response.

(unitron) writes:

Randy Yates wrote in message ...
Hello,

Our church is considering installing an array of single-driver,
in-ceiling speakers. It would seem that, given N^2 speakers,
configuring an N by N array in which N columns were connected
in parallel with each of the N speakers in a column connected
in series would be the way to go. This would provide the amplifier
with the impedance of one speaker and would evenly divide the
power among the N^2 speakers.

Is this a bad idea? Are there other considerations to be made?
Any comments otherwise?

Fellow NC resident (and church sound guy) here. I suppose you can do
the series/parallel thing with an almost infinite even number of
speakers, but you'll probably need to divide the total number of
speakers into the output wattage of the amp to see if each speaker
will get enough wattage to drive them all.

Yeah, but that's true in some sense anyway. That is, the basically
problem of having a lot of speakers and the corresponding amount of
power to drive them to usable levels is going to be there no matter
what interface (70V or series/parallel) you use.

Also, if all these
speakers are going to be in the same room, like say the sanctuary or
fellowship hall, you may find that the acoustic properties of the room
may require that not all the speakers run at the same volume.

What acoustic conditions could result in this scenario? I could see it
if the room was irregular (especially if the ceiling was lower in some
sections).

On the
other hand if you're looking to distribute sound to several different
rooms like the vestibule, choir room, bridal room, nursery, etc., then
a 70 Volt system is pretty much the only way to go.

We do want to include those rooms. That could be a deciding factor.

You may want to
consult a professional sound contractor. Tri-Tronics over in
Lillington (910-893-4183) have been at it a long time and seem to have
some idea what they're doing.

Thanks, but I think I'd like to keep it DIY. I've got a couple degrees
in electrical engineering, so I oughta' be able to handle it. But
thanks for the reference. Could you believe that our pastor was just
going to go out and buy another couple of speakers to replace some
oldies we have hanging up front and call it good? And one of his main
concerns was feedback while in front of the pulpit for communion!

Speaking of feedback, it seems that an array is going to be better
than two up-front speakers, no? Because the loop gain from the
microphone through the system and back is going to be less since the
power is distributed spatially over all the speakers and only a few
speakers in the array will be significant in the acoustic path.
--
% Randy Yates % "How's life on earth?
%% Fuquay-Varina, NC % ... What is it worth?"
%%% 919-577-9882 % 'Mission (A World Record)',
%%%% % *A New World Record*, ELO
http://home.earthlink.net/~yatescr

Randy Yates wrote in message ...
Hey Unitron,

Sorry for the late response.

(unitron) writes:

Randy Yates wrote in message ...
Hello,

Our church is considering installing an array of single-driver,
in-ceiling speakers. It would seem that, given N^2 speakers,
configuring an N by N array in which N columns were connected
in parallel with each of the N speakers in a column connected
in series would be the way to go. This would provide the amplifier
with the impedance of one speaker and would evenly divide the
power among the N^2 speakers.

Is this a bad idea? Are there other considerations to be made?
Any comments otherwise?

Fellow NC resident (and church sound guy) here. I suppose you can do
the series/parallel thing with an almost infinite even number of
speakers, but you'll probably need to divide the total number of
speakers into the output wattage of the amp to see if each speaker
will get enough wattage to drive them all.

Yeah, but that's true in some sense anyway. That is, the basically
problem of having a lot of speakers and the corresponding amount of
power to drive them to usable levels is going to be there no matter
what interface (70V or series/parallel) you use.

Also, if all these
speakers are going to be in the same room, like say the sanctuary or
fellowship hall, you may find that the acoustic properties of the room
may require that not all the speakers run at the same volume.

What acoustic conditions could result in this scenario? I could see it
if the room was irregular (especially if the ceiling was lower in some
sections).

On the
other hand if you're looking to distribute sound to several different
rooms like the vestibule, choir room, bridal room, nursery, etc., then
a 70 Volt system is pretty much the only way to go.

We do want to include those rooms. That could be a deciding factor.

You may want to
consult a professional sound contractor. Tri-Tronics over in
Lillington (910-893-4183) have been at it a long time and seem to have
some idea what they're doing.

Thanks, but I think I'd like to keep it DIY. I've got a couple degrees
in electrical engineering, so I oughta' be able to handle it. But
thanks for the reference. Could you believe that our pastor was just
going to go out and buy another couple of speakers to replace some
oldies we have hanging up front and call it good? And one of his main
concerns was feedback while in front of the pulpit for communion!

Speaking of feedback, it seems that an array is going to be better
than two up-front speakers, no? Because the loop gain from the
microphone through the system and back is going to be less since the
power is distributed spatially over all the speakers and only a few
speakers in the array will be significant in the acoustic path.

I should probaly snip, but not sure where,so...

70 Volt distribution is used for the same reason that CP&L (Progress
Energy since they bought that Florida outfit) doesn't run 220 the
whole way from the plant to your house--higher voltage means lower
current at same wattage means smaller, cheaper wires for long cable
runs.
For the vestibule, choir room, bridal room, nursery, etc., you don't
need as "hi-fi" a signal as you do to the sound reinforcement speakers
in the sanctuary, so you can send a separate signal from the board
into a, by comparison, cheap mono Bogen PA amp with 70 volt output for
those rooms and wall mount an "L" or "H" (forget which) pad type
volume control in each. If the praise team is wailing away practicing
in the sanctuary, which goes through the board and that cheap Bogen,
and the traditional choir is trying to rehearse in the choir room and
they're trying to get the babies to sleep in the nursery it helps for
each room to be able to vary their speaker from loud down to off.
Most sanctuaries don't have flat 8' ceilings so in-ceiling speakers
will be farther away from some of the audience than others depending
on how high the ceiling is directly above them. I'd be wary of
in-ceiling in a sanctuary anyway. Remember, in sound reinforcement
you want to be able to close your eyes, point to where you hear the
sound coming from, and then open your eyes to find yourself pointing
at the original sound source, usually the stage, pulpit, and/or choir
loft. That doesn't necessarily mean that all your loudspeakers have
to be mounted there, but the extra sound which you add electronically
to that which is already present acoustically should only be loud
enough to add in to (and arrive at the same time as) the acoustic
sound without being loud enough to change the perception of direction.
Those 2 upfront speakers may need augmenting rather than replacing
and the feedback problem may be best handled by re-positioning them.
You may need to borrow some equipment--extra speakers and amps and
such--(and dragoon some church personnel) and experiment with the
sanctuary setup to see what does and doesn't work (although this will
probably take longer/be more trouble than hiring somebody that
specialises in this sort of thing, even if you just get them to do the
design and supply all the labor yourselves).
If you want to bat this back and forth over the phone email me
) when's a good time to call (assuming that
number on your page is valid :-)
P.S. In my earlier post about wireless assisted listening systems
that should have been "miracle", not "mracle". God may save me, but
not, unfortunately, from my typos.

Randy Yates wrote in message ...
Hey Unitron,

Sorry for the late response.

(unitron) writes:

Randy Yates wrote in message ...
Hello,

Our church is considering installing an array of single-driver,
in-ceiling speakers. It would seem that, given N^2 speakers,
configuring an N by N array in which N columns were connected
in parallel with each of the N speakers in a column connected
in series would be the way to go. This would provide the amplifier
with the impedance of one speaker and would evenly divide the
power among the N^2 speakers.

Is this a bad idea? Are there other considerations to be made?
Any comments otherwise?

Fellow NC resident (and church sound guy) here. I suppose you can do
the series/parallel thing with an almost infinite even number of
speakers, but you'll probably need to divide the total number of
speakers into the output wattage of the amp to see if each speaker
will get enough wattage to drive them all.

Yeah, but that's true in some sense anyway. That is, the basically
problem of having a lot of speakers and the corresponding amount of
power to drive them to usable levels is going to be there no matter
what interface (70V or series/parallel) you use.

Also, if all these
speakers are going to be in the same room, like say the sanctuary or
fellowship hall, you may find that the acoustic properties of the room
may require that not all the speakers run at the same volume.

What acoustic conditions could result in this scenario? I could see it
if the room was irregular (especially if the ceiling was lower in some
sections).

On the
other hand if you're looking to distribute sound to several different
rooms like the vestibule, choir room, bridal room, nursery, etc., then
a 70 Volt system is pretty much the only way to go.

We do want to include those rooms. That could be a deciding factor.

You may want to
consult a professional sound contractor. Tri-Tronics over in
Lillington (910-893-4183) have been at it a long time and seem to have
some idea what they're doing.

Thanks, but I think I'd like to keep it DIY. I've got a couple degrees
in electrical engineering, so I oughta' be able to handle it. But
thanks for the reference. Could you believe that our pastor was just
going to go out and buy another couple of speakers to replace some
oldies we have hanging up front and call it good? And one of his main
concerns was feedback while in front of the pulpit for communion!

Speaking of feedback, it seems that an array is going to be better
than two up-front speakers, no? Because the loop gain from the
microphone through the system and back is going to be less since the
power is distributed spatially over all the speakers and only a few
speakers in the array will be significant in the acoustic path.

I should probaly snip, but not sure where,so...

70 Volt distribution is used for the same reason that CP&L (Progress
Energy since they bought that Florida outfit) doesn't run 220 the
whole way from the plant to your house--higher voltage means lower
current at same wattage means smaller, cheaper wires for long cable
runs.
For the vestibule, choir room, bridal room, nursery, etc., you don't
need as "hi-fi" a signal as you do to the sound reinforcement speakers
in the sanctuary, so you can send a separate signal from the board
into a, by comparison, cheap mono Bogen PA amp with 70 volt output for
those rooms and wall mount an "L" or "H" (forget which) pad type
volume control in each. If the praise team is wailing away practicing
in the sanctuary, which goes through the board and that cheap Bogen,
and the traditional choir is trying to rehearse in the choir room and
they're trying to get the babies to sleep in the nursery it helps for
each room to be able to vary their speaker from loud down to off.
Most sanctuaries don't have flat 8' ceilings so in-ceiling speakers
will be farther away from some of the audience than others depending
on how high the ceiling is directly above them. I'd be wary of
in-ceiling in a sanctuary anyway. Remember, in sound reinforcement
you want to be able to close your eyes, point to where you hear the
sound coming from, and then open your eyes to find yourself pointing
at the original sound source, usually the stage, pulpit, and/or choir
loft. That doesn't necessarily mean that all your loudspeakers have
to be mounted there, but the extra sound which you add electronically
to that which is already present acoustically should only be loud
enough to add in to (and arrive at the same time as) the acoustic
sound without being loud enough to change the perception of direction.
Those 2 upfront speakers may need augmenting rather than replacing
and the feedback problem may be best handled by re-positioning them.
You may need to borrow some equipment--extra speakers and amps and
such--(and dragoon some church personnel) and experiment with the
sanctuary setup to see what does and doesn't work (although this will
probably take longer/be more trouble than hiring somebody that
specialises in this sort of thing, even if you just get them to do the
design and supply all the labor yourselves).
If you want to bat this back and forth over the phone email me
) when's a good time to call (assuming that
number on your page is valid :-)
P.S. In my earlier post about wireless assisted listening systems
that should have been "miracle", not "mracle". God may save me, but
not, unfortunately, from my typos.

Randy Yates wrote in message ...
Hey Unitron,

Sorry for the late response.

(unitron) writes:

Randy Yates wrote in message ...
Hello,

Our church is considering installing an array of single-driver,
in-ceiling speakers. It would seem that, given N^2 speakers,
configuring an N by N array in which N columns were connected
in parallel with each of the N speakers in a column connected
in series would be the way to go. This would provide the amplifier
with the impedance of one speaker and would evenly divide the
power among the N^2 speakers.

Is this a bad idea? Are there other considerations to be made?
Any comments otherwise?

Fellow NC resident (and church sound guy) here. I suppose you can do
the series/parallel thing with an almost infinite even number of
speakers, but you'll probably need to divide the total number of
speakers into the output wattage of the amp to see if each speaker
will get enough wattage to drive them all.

Yeah, but that's true in some sense anyway. That is, the basically
problem of having a lot of speakers and the corresponding amount of
power to drive them to usable levels is going to be there no matter
what interface (70V or series/parallel) you use.

Also, if all these
speakers are going to be in the same room, like say the sanctuary or
fellowship hall, you may find that the acoustic properties of the room
may require that not all the speakers run at the same volume.

What acoustic conditions could result in this scenario? I could see it
if the room was irregular (especially if the ceiling was lower in some
sections).

On the
other hand if you're looking to distribute sound to several different
rooms like the vestibule, choir room, bridal room, nursery, etc., then
a 70 Volt system is pretty much the only way to go.

We do want to include those rooms. That could be a deciding factor.

You may want to
consult a professional sound contractor. Tri-Tronics over in
Lillington (910-893-4183) have been at it a long time and seem to have
some idea what they're doing.

Thanks, but I think I'd like to keep it DIY. I've got a couple degrees
in electrical engineering, so I oughta' be able to handle it. But
thanks for the reference. Could you believe that our pastor was just
going to go out and buy another couple of speakers to replace some
oldies we have hanging up front and call it good? And one of his main
concerns was feedback while in front of the pulpit for communion!

Speaking of feedback, it seems that an array is going to be better
than two up-front speakers, no? Because the loop gain from the
microphone through the system and back is going to be less since the
power is distributed spatially over all the speakers and only a few
speakers in the array will be significant in the acoustic path.

I should probaly snip, but not sure where,so...

70 Volt distribution is used for the same reason that CP&L (Progress
Energy since they bought that Florida outfit) doesn't run 220 the
whole way from the plant to your house--higher voltage means lower
current at same wattage means smaller, cheaper wires for long cable
runs.
For the vestibule, choir room, bridal room, nursery, etc., you don't
need as "hi-fi" a signal as you do to the sound reinforcement speakers
in the sanctuary, so you can send a separate signal from the board
into a, by comparison, cheap mono Bogen PA amp with 70 volt output for
those rooms and wall mount an "L" or "H" (forget which) pad type
volume control in each. If the praise team is wailing away practicing
in the sanctuary, which goes through the board and that cheap Bogen,
and the traditional choir is trying to rehearse in the choir room and
they're trying to get the babies to sleep in the nursery it helps for
each room to be able to vary their speaker from loud down to off.
Most sanctuaries don't have flat 8' ceilings so in-ceiling speakers
will be farther away from some of the audience than others depending
on how high the ceiling is directly above them. I'd be wary of
in-ceiling in a sanctuary anyway. Remember, in sound reinforcement
you want to be able to close your eyes, point to where you hear the
sound coming from, and then open your eyes to find yourself pointing
at the original sound source, usually the stage, pulpit, and/or choir
loft. That doesn't necessarily mean that all your loudspeakers have
to be mounted there, but the extra sound which you add electronically
to that which is already present acoustically should only be loud
enough to add in to (and arrive at the same time as) the acoustic
sound without being loud enough to change the perception of direction.
Those 2 upfront speakers may need augmenting rather than replacing
and the feedback problem may be best handled by re-positioning them.
You may need to borrow some equipment--extra speakers and amps and
such--(and dragoon some church personnel) and experiment with the
sanctuary setup to see what does and doesn't work (although this will
probably take longer/be more trouble than hiring somebody that
specialises in this sort of thing, even if you just get them to do the
design and supply all the labor yourselves).
If you want to bat this back and forth over the phone email me
) when's a good time to call (assuming that
number on your page is valid :-)
P.S. In my earlier post about wireless assisted listening systems
that should have been "miracle", not "mracle". God may save me, but
not, unfortunately, from my typos.

Randy Yates wrote in message ...
Hey Unitron,

Sorry for the late response.

(unitron) writes:

Randy Yates wrote in message ...
Hello,

Our church is considering installing an array of single-driver,
in-ceiling speakers. It would seem that, given N^2 speakers,
configuring an N by N array in which N columns were connected
in parallel with each of the N speakers in a column connected
in series would be the way to go. This would provide the amplifier
with the impedance of one speaker and would evenly divide the
power among the N^2 speakers.

Is this a bad idea? Are there other considerations to be made?
Any comments otherwise?

Fellow NC resident (and church sound guy) here. I suppose you can do
the series/parallel thing with an almost infinite even number of
speakers, but you'll probably need to divide the total number of
speakers into the output wattage of the amp to see if each speaker
will get enough wattage to drive them all.

Yeah, but that's true in some sense anyway. That is, the basically
problem of having a lot of speakers and the corresponding amount of
power to drive them to usable levels is going to be there no matter
what interface (70V or series/parallel) you use.

Also, if all these
speakers are going to be in the same room, like say the sanctuary or
fellowship hall, you may find that the acoustic properties of the room
may require that not all the speakers run at the same volume.

What acoustic conditions could result in this scenario? I could see it
if the room was irregular (especially if the ceiling was lower in some
sections).

On the
other hand if you're looking to distribute sound to several different
rooms like the vestibule, choir room, bridal room, nursery, etc., then
a 70 Volt system is pretty much the only way to go.

We do want to include those rooms. That could be a deciding factor.

You may want to
consult a professional sound contractor. Tri-Tronics over in
Lillington (910-893-4183) have been at it a long time and seem to have
some idea what they're doing.

Thanks, but I think I'd like to keep it DIY. I've got a couple degrees
in electrical engineering, so I oughta' be able to handle it. But
thanks for the reference. Could you believe that our pastor was just
going to go out and buy another couple of speakers to replace some
oldies we have hanging up front and call it good? And one of his main
concerns was feedback while in front of the pulpit for communion!

Speaking of feedback, it seems that an array is going to be better
than two up-front speakers, no? Because the loop gain from the
microphone through the system and back is going to be less since the
power is distributed spatially over all the speakers and only a few
speakers in the array will be significant in the acoustic path.

I should probaly snip, but not sure where,so...

70 Volt distribution is used for the same reason that CP&L (Progress
Energy since they bought that Florida outfit) doesn't run 220 the
whole way from the plant to your house--higher voltage means lower
current at same wattage means smaller, cheaper wires for long cable
runs.
For the vestibule, choir room, bridal room, nursery, etc., you don't
need as "hi-fi" a signal as you do to the sound reinforcement speakers
in the sanctuary, so you can send a separate signal from the board
into a, by comparison, cheap mono Bogen PA amp with 70 volt output for
those rooms and wall mount an "L" or "H" (forget which) pad type
volume control in each. If the praise team is wailing away practicing
in the sanctuary, which goes through the board and that cheap Bogen,
and the traditional choir is trying to rehearse in the choir room and
they're trying to get the babies to sleep in the nursery it helps for
each room to be able to vary their speaker from loud down to off.
Most sanctuaries don't have flat 8' ceilings so in-ceiling speakers
will be farther away from some of the audience than others depending
on how high the ceiling is directly above them. I'd be wary of
in-ceiling in a sanctuary anyway. Remember, in sound reinforcement
you want to be able to close your eyes, point to where you hear the
sound coming from, and then open your eyes to find yourself pointing
at the original sound source, usually the stage, pulpit, and/or choir
loft. That doesn't necessarily mean that all your loudspeakers have
to be mounted there, but the extra sound which you add electronically
to that which is already present acoustically should only be loud
enough to add in to (and arrive at the same time as) the acoustic
sound without being loud enough to change the perception of direction.
Those 2 upfront speakers may need augmenting rather than replacing
and the feedback problem may be best handled by re-positioning them.
You may need to borrow some equipment--extra speakers and amps and
such--(and dragoon some church personnel) and experiment with the
sanctuary setup to see what does and doesn't work (although this will
probably take longer/be more trouble than hiring somebody that
specialises in this sort of thing, even if you just get them to do the
design and supply all the labor yourselves).
If you want to bat this back and forth over the phone email me
) when's a good time to call (assuming that
number on your page is valid :-)
P.S. In my earlier post about wireless assisted listening systems
that should have been "miracle", not "mracle". God may save me, but
not, unfortunately, from my typos.

El Meda wrote
Randy Yates wrote:
I suggest however that you connect the
N speakers in each column in parallel, and then each parallel array in
series with each other. That way, if one of the speakers goes bad and
opens, it won't mute the entire column it is in.
But then you have the alternate problem - one speaker which shorts will
take down the whole array. But thank you for provoking some more thought
on the matter.
Not the whole array, only the column it's in: the total impedance will
only be reduced by R/N. Besides in my experience the speaker won't
usually short, and frequently open.

Nonetheless, huge series-parallel arrays can be a right pain to
faultfind on and are rather inflexible.

If it's essential to use speakers without inbuilt transformers, then
I'd suggest running the main runs in 70V and having one cluster of 4
speakers in series-parallel per transformer. That cuts down the
number of xfrs required to 1/4 of the ceiling speakers, and gives the
other benefits of 70V line, i.e. easy parallel connection, easier
fault finding, easy to adjust individual speaker (or each cluster)
levels, taking feeds out to side rooms, etc.

Owain

El Meda wrote
Randy Yates wrote:
I suggest however that you connect the
N speakers in each column in parallel, and then each parallel array in
series with each other. That way, if one of the speakers goes bad and
opens, it won't mute the entire column it is in.
But then you have the alternate problem - one speaker which shorts will
take down the whole array. But thank you for provoking some more thought
on the matter.
Not the whole array, only the column it's in: the total impedance will
only be reduced by R/N. Besides in my experience the speaker won't
usually short, and frequently open.

Nonetheless, huge series-parallel arrays can be a right pain to
faultfind on and are rather inflexible.

If it's essential to use speakers without inbuilt transformers, then
I'd suggest running the main runs in 70V and having one cluster of 4
speakers in series-parallel per transformer. That cuts down the
number of xfrs required to 1/4 of the ceiling speakers, and gives the
other benefits of 70V line, i.e. easy parallel connection, easier
fault finding, easy to adjust individual speaker (or each cluster)
levels, taking feeds out to side rooms, etc.

Owain

El Meda wrote
Randy Yates wrote:
I suggest however that you connect the
N speakers in each column in parallel, and then each parallel array in
series with each other. That way, if one of the speakers goes bad and
opens, it won't mute the entire column it is in.
But then you have the alternate problem - one speaker which shorts will
take down the whole array. But thank you for provoking some more thought
on the matter.
Not the whole array, only the column it's in: the total impedance will
only be reduced by R/N. Besides in my experience the speaker won't
usually short, and frequently open.

Nonetheless, huge series-parallel arrays can be a right pain to
faultfind on and are rather inflexible.

If it's essential to use speakers without inbuilt transformers, then
I'd suggest running the main runs in 70V and having one cluster of 4
speakers in series-parallel per transformer. That cuts down the
number of xfrs required to 1/4 of the ceiling speakers, and gives the
other benefits of 70V line, i.e. easy parallel connection, easier
fault finding, easy to adjust individual speaker (or each cluster)
levels, taking feeds out to side rooms, etc.

Owain

El Meda wrote
Randy Yates wrote:
I suggest however that you connect the
N speakers in each column in parallel, and then each parallel array in
series with each other. That way, if one of the speakers goes bad and
opens, it won't mute the entire column it is in.
But then you have the alternate problem - one speaker which shorts will
take down the whole array. But thank you for provoking some more thought
on the matter.
Not the whole array, only the column it's in: the total impedance will
only be reduced by R/N. Besides in my experience the speaker won't
usually short, and frequently open.

Nonetheless, huge series-parallel arrays can be a right pain to
faultfind on and are rather inflexible.

If it's essential to use speakers without inbuilt transformers, then
I'd suggest running the main runs in 70V and having one cluster of 4
speakers in series-parallel per transformer. That cuts down the
number of xfrs required to 1/4 of the ceiling speakers, and gives the
other benefits of 70V line, i.e. easy parallel connection, easier
fault finding, easy to adjust individual speaker (or each cluster)
levels, taking feeds out to side rooms, etc.

Owain