matching impedances
 

I need to take an output from a 25 volt speaker line and feed it to an
amplifier to service a remote area for additional power. I plan to
tie the .25w tap of the primary of a 25 volt matching transformer to
the line and then connect the secondary to the booster amplifier
balanced line input. I suspect that the level at the transformer
secondary will be too high, so I envision having to pad or attenuate
it down substantially. I would do this by adding series resisters to
each secondary side. I know this may not exactly match the amplifier
impedance but I'm not too concerned about that. Does anyone have a
feel for the values of series resisters that I can use on the
secondary of the transformer to bring the line down to a level so that
the balance line input of the amplifier will not be overloaded?
Thank you very much for any advice

-Lenny

matching impedances
 

" wrote:

I need to take an output from a 25 volt speaker line and feed it to an
amplifier to service a remote area for additional power. I plan to
tie the .25w tap of the primary of a 25 volt matching transformer to
the line and then connect the secondary to the booster amplifier
balanced line input. I suspect that the level at the transformer
secondary will be too high, so I envision having to pad or attenuate
it down substantially. I would do this by adding series resisters to
each secondary side. I know this may not exactly match the amplifier
impedance but I'm not too concerned about that. Does anyone have a
feel for the values of series resisters that I can use on the
secondary of the transformer to bring the line down to a level so that
the balance line input of the amplifier will not be overloaded?
Thank you very much for any advice


I always used a 10k resistor to a 5 K pot, and set the level from
there. If it is here it can be tampered with, you might want to put an
internal 100K pot, then set the level control to around 74% of the level
you want with the internal pot. Also, don't bond the primary and
secondary commons toothier to avoid a ground loop.


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The first sign of insanity is denying that you're crazy.

matching impedances
 

On Sep 25, 8:53*pm, "Michael A. Terrell"
wrote:
" wrote:

I need to take an output from a 25 volt speaker line and feed it to an
amplifier to service a remote area for additional power. *I plan to
tie the .25w tap of the primary of a 25 volt matching transformer to
the line and then connect the secondary to the booster amplifier
balanced line input. I suspect that the level at the transformer
secondary will be too high, so I envision having to pad or attenuate
it down substantially. I would do this by adding series resisters to
each secondary side. *I know this may not exactly match the amplifier
impedance but I'm not too concerned about that. Does anyone have a
feel for the values of series resisters that I can use on the
secondary of the transformer to bring the line down to a level so that
the balance line input of the amplifier will not be overloaded?
Thank you very much for any advice

* *I always used a 10k resistor to a 5 K pot, and set the level from
there. *If it is here it can be tampered with, you might want to put an
internal 100K pot, then set the level control to around 74% of the level
you want with the internal pot. *Also, don't bond the primary and
secondary commons toothier to avoid a ground loop.

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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

Thanks Michael. I'm bringing a lot of spare parts to the job with me
today and I'll let you know how it all works out. Best regards, Lenny.

matching impedances
 

" wrote:

Thanks Michael. I'm bringing a lot of spare parts to the job with me
today and I'll let you know how it all works out. Best regards, Lenny.


You're welcome. I used to build those a couple at a time, to have
extras in my truck. :)


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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

matching impedances
 

On Sep 26, 10:51*am, "Michael A. Terrell"
wrote:
" wrote:

Thanks Michael. I'm bringing a lot of spare parts to the job with me
today and I'll let you know how it all works out. Best regards, Lenny.

* *You're welcome. I used to build those a couple at a time, to have
extras in my truck. :)

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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

Michael
I used two 10K resistors off the secondary of a 70.7V transformer. I
felt that this would maintain a balanced line input to my amp. The
primary was tied to the incoming 70V line and was tapped at 4W. The
only balanced line inputs to the amp were mic 1 and mic 2. With the
10K resistors in series the level into the balanced mic input of the
amp was perfect. The amplifier was a Bogen 60W unit. We added two more
speakers to the system for a total of 4 all tapped at 4W. This is a
commercial kitchen with the unbelievable noise level of a subway
tunnel. Now they'll have no trouble hearing the pages. Thanks again
for the advice. Another fire put out. Best regards, Lenny.

matching impedances
 

" wrote:

On Sep 26, 10:51 am, "Michael A. Terrell"
wrote:
" wrote:

Thanks Michael. I'm bringing a lot of spare parts to the job with me
today and I'll let you know how it all works out. Best regards, Lenny.

You're welcome. I used to build those a couple at a time, to have
extras in my truck. :)

Michael
I used two 10K resistors off the secondary of a 70.7V transformer. I
felt that this would maintain a balanced line input to my amp. The
primary was tied to the incoming 70V line and was tapped at 4W. The
only balanced line inputs to the amp were mic 1 and mic 2. With the
10K resistors in series the level into the balanced mic input of the
amp was perfect. The amplifier was a Bogen 60W unit. We added two more
speakers to the system for a total of 4 all tapped at 4W. This is a
commercial kitchen with the unbelievable noise level of a subway
tunnel. Now they'll have no trouble hearing the pages. Thanks again
for the advice. Another fire put out. Best regards, Lenny.


You're welcome. If that was a typical Bogen amp, the inputs are
transformer isolated 150 or 600 ohm impedance.


Try putting in a system in a corrugated box plant sometime if you
want noise! ;-) 35 watts covered the whole plant, except near the
corrugators, and each had their own 100 watt amp, with PA horns six feet
away from each operator.


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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.

matching impedances
 

On Sep 27, 1:33*pm, "Michael A. Terrell"
wrote:
" wrote:

On Sep 26, 10:51 am, "Michael A. Terrell"
wrote:
" wrote:

Thanks Michael. I'm bringing a lot of spare parts to the job with me
today and I'll let you know how it all works out. Best regards, Lenny.

* *You're welcome. I used to build those a couple at a time, to have
extras in my truck. :)

Michael
I used two 10K resistors off the secondary of a 70.7V transformer. I
felt that this would maintain a balanced line input to my amp. The
primary was tied to the incoming 70V line and was tapped at 4W. The
only balanced line inputs to the amp were mic 1 and mic 2. With the
10K resistors in series the level into the balanced mic input of the
amp was perfect. The amplifier was a Bogen 60W unit. We added two more
speakers to the system for a total of 4 all tapped at 4W. This is a
commercial kitchen with the unbelievable noise level of a subway
tunnel. Now they'll have no trouble hearing the pages. Thanks again
for the advice. Another fire put out. Best regards, Lenny.

* *You're welcome. *If that was a typical Bogen amp, the inputs are
transformer isolated 150 or 600 ohm impedance.

* *Try putting in a system in a corrugated box plant sometime if you
want noise! ;-) *35 watts covered the whole plant, except near the
corrugators, and each had their own 100 watt amp, with PA horns six feet
away from each operator.

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There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.- Hide quoted text -

- Show quoted text -

This is an interesting group
I just had an impedance issue i got help with on a project that I am
working on, in summary
I used CO sensors in a parking garage the rating on the comunication
bus is 2000ft, When I designed the project during estimation I took a
risk to strech to 3000 based on the probability that the voltage drop
would not migatate me. Anyhow to make a very long story short, it
turned out between my low volatge sub and my inherient nature for
taking small calculated risks, the com was 3500 ft, I tried to figure
out the best end of the line terminator , going back to the impedance
matching topic that sparked my interest, after calling some experts, I
got the matched impedance, but still need to and another 50VA
transformer.... lesson learned on my part

Thanks for sharing
Allan J Federman

matching impedances
 

This is an interesting group
I just had an impedance issue i got help with on a project that I am
working on, in summary
I used CO sensors in a parking garage the rating on the comunication
bus is 2000ft, When I designed the project during estimation I took a
risk to strech to 3000 based on the probability that the voltage drop
would not migatate me. Anyhow to make a very long story short, it
turned out between my low volatge sub and my inherient nature for
taking small calculated risks, the com was 3500 ft, I tried to figure
out the best end of the line terminator , going back to the impedance
matching topic that sparked my interest, after calling some experts, I
got the matched impedance, but still need to and another 50VA
transformer.... lesson learned on my part

Thanks for sharing
Allan J Federman


Mr. Federman, your writing verges on the incomprehensible. I have little
idea what you're talking about or trying to say.

I hope communications with your customers aren't so opaque.

matching impedances
 

On Sep 28, 11:04*pm, "William Sommerwerck"
wrote:
This is an interesting group
I just had an impedance issue i got help with on a project that I am
working on, in summary
I used CO sensors in a parking garage the rating on the comunication
bus is 2000ft, *When I designed the project during estimation I took a
risk to strech to 3000 based on the probability that the voltage drop
would not migatate me. Anyhow to make a very long story short, it
turned out between my low volatge sub and my inherient nature for
taking small calculated risks, the com was 3500 ft, I tried to figure
out the best end of the line terminator , going back to the impedance
matching topic that sparked my interest, after calling some experts, I
got the matched impedance, but still need to and another 50VA
transformer.... lesson learned on my part

Thanks for sharing
Allan J Federman


Mr. Federman, your writing verges on the incomprehensible. I have little
idea what you're talking about or trying to say.

I hope communications with your customers aren't so opaque.

I think he'd be talking DC signals from the CO sensors, not
impedances? But no expertise here concerning remote indicating sensors.

matching impedances
 

On Sep 29, 5:19*pm, terry wrote:
On Sep 28, 11:04*pm, "William Sommerwerck"





wrote:
This is an interesting group
I just had an impedance issue i got help with on a project that I am
working on, in summary
I used CO sensors in a parking garage the rating on the comunication
bus is 2000ft, *When I designed the project during estimation I took a
risk to strech to 3000 based on the probability that the voltage drop
would not migatate me. Anyhow to make a very long story short, it
turned out between my low volatge sub and my inherient nature for
taking small calculated risks, the com was 3500 ft, I tried to figure
out the best end of the line terminator , going back to the impedance
matching topic that sparked my interest, after calling some experts, I
got the matched impedance, but still need to and another 50VA
transformer.... lesson learned on my part

Thanks for sharing
Allan J Federman


Mr. Federman, your writing verges on the incomprehensible. I have little
idea what you're talking about or trying to say.

I hope communications with your customers aren't so opaque.

I think he'd be talking DC signals from the CO sensors, not
impedances? But no expertise here concerning remote indicating sensors.- Hide quoted text -

- Show quoted text -

I don't feel so badly now, as I couldn't really figure out what he was
talking about either. However it did sound interesting so if the OP
could please rephrase it a little better we all might be able to
participate. I always proof read my work.Lenny.