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Jim Weir- need help on aux audio inputs to PM-3000 intercom



 
 
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  #1  
Old June 6th 06, 02:56 AM posted to rec.aviation.homebuilt
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Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Hi Jim,

I spoke with you earlier today about this.
I have 3 aux audio inputs that I want to run through my PM-3000
intercom. The problem is the PM-3000 does not support any unswitched
aux inputs. I had tried running them through the entertainment input
but this results in the audio only playing through one speaker (stereo
system). If I run them to both the left and right inputs this
permenently shorts the left and right sides and I end up with a mono
entertainment system. Can I run these on the same line as the com radio
input? Is there something available to to make this work or do I need
to buy an audio panel?


Thanks,
Danny

  #2  
Old June 7th 06, 12:06 AM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Danny ...

Sorry, but I stay as far away from stereo systems as I possibly can...

Here's the canned answer:

******************************

Stereo In The Aircraft

RST does not produce any stereo intercoms, audio panels, headsets, or other
devices that reproduce stereo music. If you are absolutely determined to
have stereo in your aircraft, you might just as well stop reading now,
because anything we have to say isn't going to change your mind.

We made a conscious business and engineering decision not to produce any
product for stereo. There are good aviation and engineering reasons for
this.

First, a little background music or listening to the ballgame in a cockpit
environment isn't all that bad. Sometimes flying is miles and miles of
nothing but miles and miles. On the other hand, I know from my own love of
music that when there is a particularly good cut playing on my home stereo
and I have the headphones on (try "Sweet Sir Galahad" by Baez or "Minstrel
Of The Dawn" by Lightfoot at somewhere slightly below the threshold of pain
in the 'phones to see what I mean) that I get totally lost within the music
and the world just sort of blurs away. Just about the LAST thing I want in
an airplane is a pilot that has zoned out on music and is just holding the
controls to have something to do with their hands. That's item #1.

Second, stereo is expensive. Yes, I understand that FLYING is expensive,
too, but to go to the expense of specially-designed headphones, intercoms,
audio panels, and all the rest of it seems to us to be on the other side of
reasonable. Our company thrust has, and always will be, to make flying
affordable for everybody. That's point #2.

Now to the engineering stuff. Suppose you try and take your stereo headset
and fly in somebody else's airplane that is "regular airplane". Will your
stereo headset work without the trick little switch on the cable to convert
it to a monophonic headset? No, you will hear one ear of the conversation
only. And what did that little switch do? It put both earphones in
parallel, which cut the impedance of the headset in half. Properly
designed, this MIGHT not be noticeable to the aircraft radio, or it might.
Since airplane radios weren't designed to figure out whether or not you were
messing around with a stereo headset, the manufacturer didn't worry about
making sure his radio would drive that low of an impedance.

Even worse, if somebody else takes his standard aircraft headset and puts it
into your stereo airplane jack, it will short out one of the channels.
Depending on the design of the intercom, the best you can hope for is that
one stereo channel will be dead in everybody's headphones. Second worst is
that the short on that channel will blow out the amplifier for that channel.
In a really lousy design, that short will cause the whole intercom/audio
panel to fail, leaving you without any headphone audio at all.

Given all these reasons, RST has decided not to produce any stereo
equipment. While it probably won't sway your decision for stereo in your
airplane, we thought you should at least consider these problems.

Jim

**************************************************
"Danny" wrote in message
oups.com...
Hi Jim,

I spoke with you earlier today about this.
I have 3 aux audio inputs that I want to run through my PM-3000
intercom. The problem is the PM-3000 does not support any unswitched
aux inputs. I had tried running them through the entertainment input
but this results in the audio only playing through one speaker (stereo
system). If I run them to both the left and right inputs this
permenently shorts the left and right sides and I end up with a mono
entertainment system. Can I run these on the same line as the com radio
input? Is there something available to to make this work or do I need
to buy an audio panel?


Thanks,
Danny



  #3  
Old June 7th 06, 12:07 AM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom


"Danny" wrote in message
oups.com...
Hi Jim,

I spoke with you earlier today about this.
I have 3 aux audio inputs that I want to run through my PM-3000
intercom. Thanks,
Danny


I stay as far away from stereo in the aircraft as I can, so I'm sorry I
don't have an answer for you.

HEre's my "canned" answer::

******************************

Stereo In The Aircraft

RST does not produce any stereo intercoms, audio panels, headsets, or other
devices that reproduce stereo music. If you are absolutely determined to
have stereo in your aircraft, you might just as well stop reading now,
because anything we have to say isn't going to change your mind.

We made a conscious business and engineering decision not to produce any
product for stereo. There are good aviation and engineering reasons for
this.

First, a little background music or listening to the ballgame in a cockpit
environment isn't all that bad. Sometimes flying is miles and miles of
nothing but miles and miles. On the other hand, I know from my own love of
music that when there is a particularly good cut playing on my home stereo
and I have the headphones on (try "Sweet Sir Galahad" by Baez or "Minstrel
Of The Dawn" by Lightfoot at somewhere slightly below the threshold of pain
in the 'phones to see what I mean) that I get totally lost within the music
and the world just sort of blurs away. Just about the LAST thing I want in
an airplane is a pilot that has zoned out on music and is just holding the
controls to have something to do with their hands. That's item #1.

Second, stereo is expensive. Yes, I understand that FLYING is expensive,
too, but to go to the expense of specially-designed headphones, intercoms,
audio panels, and all the rest of it seems to us to be on the other side of
reasonable. Our company thrust has, and always will be, to make flying
affordable for everybody. That's point #2.

Now to the engineering stuff. Suppose you try and take your stereo headset
and fly in somebody else's airplane that is "regular airplane". Will your
stereo headset work without the trick little switch on the cable to convert
it to a monophonic headset? No, you will hear one ear of the conversation
only. And what did that little switch do? It put both earphones in
parallel, which cut the impedance of the headset in half. Properly
designed, this MIGHT not be noticeable to the aircraft radio, or it might.
Since airplane radios weren't designed to figure out whether or not you were
messing around with a stereo headset, the manufacturer didn't worry about
making sure his radio would drive that low of an impedance.

Even worse, if somebody else takes his standard aircraft headset and puts it
into your stereo airplane jack, it will short out one of the channels.
Depending on the design of the intercom, the best you can hope for is that
one stereo channel will be dead in everybody's headphones. Second worst is
that the short on that channel will blow out the amplifier for that channel.
In a really lousy design, that short will cause the whole intercom/audio
panel to fail, leaving you without any headphone audio at all.

Given all these reasons, RST has decided not to produce any stereo
equipment. While it probably won't sway your decision for stereo in your
airplane, we thought you should at least consider these problems.

Jim

**************************************************


  #4  
Old June 7th 06, 01:08 AM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Hi Jim,
Thanks for taking the time to answer. I respect your opinions so OK, I
can live without stereo and install a PM-1000 that I have but what is
the best way to interface the aux audio input into a system that does
not provide for any other inputs other than COM from the radio and a
music input. I know I can use the music input but this gets muted
anytime someone speaks.

Danny

Danny
RST Engineering wrote:
"Danny" wrote in message
oups.com...
Hi Jim,

I spoke with you earlier today about this.
I have 3 aux audio inputs that I want to run through my PM-3000
intercom. Thanks,
Danny


I stay as far away from stereo in the aircraft as I can, so I'm sorry I
don't have an answer for you.

HEre's my "canned" answer::

******************************

Stereo In The Aircraft

RST does not produce any stereo intercoms, audio panels, headsets, or other
devices that reproduce stereo music. If you are absolutely determined to
have stereo in your aircraft, you might just as well stop reading now,
because anything we have to say isn't going to change your mind.

We made a conscious business and engineering decision not to produce any
product for stereo. There are good aviation and engineering reasons for
this.

First, a little background music or listening to the ballgame in a cockpit
environment isn't all that bad. Sometimes flying is miles and miles of
nothing but miles and miles. On the other hand, I know from my own love of
music that when there is a particularly good cut playing on my home stereo
and I have the headphones on (try "Sweet Sir Galahad" by Baez or "Minstrel
Of The Dawn" by Lightfoot at somewhere slightly below the threshold of pain
in the 'phones to see what I mean) that I get totally lost within the music
and the world just sort of blurs away. Just about the LAST thing I want in
an airplane is a pilot that has zoned out on music and is just holding the
controls to have something to do with their hands. That's item #1.

Second, stereo is expensive. Yes, I understand that FLYING is expensive,
too, but to go to the expense of specially-designed headphones, intercoms,
audio panels, and all the rest of it seems to us to be on the other side of
reasonable. Our company thrust has, and always will be, to make flying
affordable for everybody. That's point #2.

Now to the engineering stuff. Suppose you try and take your stereo headset
and fly in somebody else's airplane that is "regular airplane". Will your
stereo headset work without the trick little switch on the cable to convert
it to a monophonic headset? No, you will hear one ear of the conversation
only. And what did that little switch do? It put both earphones in
parallel, which cut the impedance of the headset in half. Properly
designed, this MIGHT not be noticeable to the aircraft radio, or it might.
Since airplane radios weren't designed to figure out whether or not you were
messing around with a stereo headset, the manufacturer didn't worry about
making sure his radio would drive that low of an impedance.

Even worse, if somebody else takes his standard aircraft headset and puts it
into your stereo airplane jack, it will short out one of the channels.
Depending on the design of the intercom, the best you can hope for is that
one stereo channel will be dead in everybody's headphones. Second worst is
that the short on that channel will blow out the amplifier for that channel.
In a really lousy design, that short will cause the whole intercom/audio
panel to fail, leaving you without any headphone audio at all.

Given all these reasons, RST has decided not to produce any stereo
equipment. While it probably won't sway your decision for stereo in your
airplane, we thought you should at least consider these problems.

Jim

**************************************************


  #5  
Old June 7th 06, 02:46 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

"E Pluribus Unum" (backside of the dollar bill; "Out Of Many, One")

The basic idea is to take each output, terminate it in a resistor of the
impedance it "wants" to see (generally a 560 ohm resistor to simulate a
standard 600 ohm load), the run all the outputs through an isolation
resistor to a summing amplifier, possibly through a switch to turn each one
on or off as desired, and then the output of the summing amplifier into the
COM input of the intercom. I'm very surprised, though, that the intercom
doesn't have an "aux" input other than the music input.

I can't describe a summing amplifier in words without pictures. Anybody got
a lead on a binaries group where I can post a picture of what I'm talking
about?

Or, go to www.rstengineering.com/kitplanes and look at U101 in the August
2002 article for an idea of what I'm talking about.

Jim





"Danny" wrote in message
oups.com...
Hi Jim,
Thanks for taking the time to answer. I respect your opinions so OK, I
can live without stereo and install a PM-1000 that I have but what is
the best way to interface the aux audio input into a system that does
not provide for any other inputs other than COM from the radio and a
music input. I know I can use the music input but this gets muted
anytime someone speaks.



  #6  
Old June 7th 06, 04:24 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Jim,
Many thanks for pointing me in the right direction.
Danny

RST Engineering wrote:
"E Pluribus Unum" (backside of the dollar bill; "Out Of Many, One")

The basic idea is to take each output, terminate it in a resistor of the
impedance it "wants" to see (generally a 560 ohm resistor to simulate a
standard 600 ohm load), the run all the outputs through an isolation
resistor to a summing amplifier, possibly through a switch to turn each one
on or off as desired, and then the output of the summing amplifier into the
COM input of the intercom. I'm very surprised, though, that the intercom
doesn't have an "aux" input other than the music input.

I can't describe a summing amplifier in words without pictures. Anybody got
a lead on a binaries group where I can post a picture of what I'm talking
about?

Or, go to www.rstengineering.com/kitplanes and look at U101 in the August
2002 article for an idea of what I'm talking about.

Jim





"Danny" wrote in message
oups.com...
Hi Jim,
Thanks for taking the time to answer. I respect your opinions so OK, I
can live without stereo and install a PM-1000 that I have but what is
the best way to interface the aux audio input into a system that does
not provide for any other inputs other than COM from the radio and a
music input. I know I can use the music input but this gets muted
anytime someone speaks.


  #7  
Old June 7th 06, 08:23 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

No such group on my newsreader.

Jim



"T o d d P a t t i s t" wrote in message
...
"RST Engineering" wrote:

Anybody got
a lead on a binaries group where I can post a picture of what I'm talking
about?


I suggest alt.binaries.pictures.aviation. It's reasonable
to post an aviation related picture there as an adjunct to
any discussion in the rec. aviation hierarchy.



  #8  
Old June 7th 06, 08:38 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Jim,

My service provider, cableone.net, has alt.binaries.pictures.aviation with a
total of 23,644 postings.

Wayne
HP-14 N990 "6F"
http://www.soaridaho.com/Schreder/HP-14/N990/N990.html
Amateur Radio W7ADK

"RST Engineering" wrote in message
...
No such group on my newsreader.

Jim



"T o d d P a t t i s t" wrote in message
...
"RST Engineering" wrote:

Anybody got
a lead on a binaries group where I can post a picture of what I'm talking
about?


I suggest alt.binaries.pictures.aviation. It's reasonable
to post an aviation related picture there as an adjunct to
any discussion in the rec. aviation hierarchy.





  #9  
Old June 7th 06, 09:14 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

("RST Engineering" wrote)
I can't describe a summing amplifier in words without pictures. Anybody
got a lead on a binaries group where I can post a picture of what I'm
talking about?

Or, go to www.rstengineering.com/kitplanes and look at U101 in the August
2002 article for an idea of what I'm talking about.



If they're JPEG's, sent them to me as e-mail attachments and I'll set them
up to a link.

Type up any info you want to go along with the attached photos.

1. (Easy on the text length - there's a limit. Amount???)
2.
3.
4.
etc.
etc.

This is what photos will look like on Yahoo:
http://makeashorterlink.com/?W26821A3D
(Wait for it...)


Montblack-at
vi
si
[.]
com

  #10  
Old June 7th 06, 09:51 PM posted to rec.aviation.homebuilt
external usenet poster
 
Posts: n/a
Default Jim Weir- need help on aux audio inputs to PM-3000 intercom

Jim is using Wildblue satellite for the ISP; I have no idea who they sub out
their newsgroup server to. I have TONS of alt.binary.photo.sexthissexthat
sites, but no aviation.

Jim



"T o d d P a t t i s t" wrote in message
...
It looks like Jim is using sisna.com, perhaps they don't
carry the binaries? I know a lot of ISPs are dropping
usenet and/or dropping the alt.binaries hierarchy.



 




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