Searching \ for '[OT]: Headphone network..' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=headphone+network
Search entire site for: 'Headphone network..'.

Exact match. Not showing close matches.
PICList Thread
'[OT]: Headphone network..'
2000\08\09@203426 by Ahmed Abasiry

picon face
Dear All...
I would like to design an audio network similar to what you see in aircrafts
where they have a central cassette player/radio and they tap out many points
connected to the seat of every passenger. The passenegers simply plug-in a
speaker headset to listen to the music. I really do not not where to start
from or what i should be looking for. Is it a simple audio amplifier with
the output tied to many jacks for users (matching problems!!??).. I'm
talking about 80+ users knowing that all users may or may not be connected
at the same time...

I appreciate any response from you all..
Thanks and Regards
Ahmed Abasiry

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

--
http://www.piclist.com hint: To leave the PICList
spam_OUTpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu>

2000\08\09@204931 by Lance Allen

picon face
On 9 Aug 2000, at 18:23, Ahmed Abasiry wrote:

> Dear All...
> I would like to design an audio network similar to what you see in aircrafts
> where they have a central cassette player/radio and they tap out many points
> connected to the seat of every passenger. The passenegers simply plug-in a
> speaker headset to listen to the music. I really do not not where to start
> from or what i should be looking for. Is it a simple audio amplifier with
> the output tied to many jacks for users (matching problems!!??).. I'm
> talking about 80+ users knowing that all users may or may not be connected
> at the same time...
>
What you have here is a Public Address (P.A.) application.
The standard way to implement this is with a 100volt (or 70 volt)
line.
What that is basically is a powerful enough audio amplifier drives
an audio transformer that produces the nominal 100volt balanced
signal on the secondary, this is distributed far and wide to the
various places the output is needed (this overcomes much of the
I2R losses). Wherever you want to "tap off the line" you fit another
transformer, with the primary in parallel with the line, the secondary
impedence matches the headphones and drives the headphones
with a suitable low voltage.This overcomes the variable impedence
problem as the transformers are always in the line and the
headphones are plugged in and out.
This is a long established technique and there are many books that
will help with further details. The transformers are all sold as
standard too, "P.A. 100 volt line equipment".
_____________________________

Lance Allen
Technical Officer
Uni of Auckland
Psych Dept
New Zealand

http://www.psych.auckland.ac.nz

_____________________________

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestKILLspamspam@spam@mitvma.mit.edu>

2000\08\09@210259 by David Duffy

flavicon
face
At 06:23 PM 09/08/00 -0600, you wrote:
>Dear All...
>I would like to design an audio network similar to what you see in aircrafts
>where they have a central cassette player/radio and they tap out many points
>connected to the seat of every passenger. The passenegers simply plug-in a
>speaker headset to listen to the music. I really do not not where to start
>from or what i should be looking for. Is it a simple audio amplifier with
>the output tied to many jacks for users (matching problems!!??).. I'm
>talking about 80+ users knowing that all users may or may not be connected
>at the same time...

You could use 70/100V distribution or perhaps a simpler way is to use an
amplifier with a 4 ohm output to drive all the headphone sockets in parallel
via 330R 1W series resistors. (160 resistors all up) The amplifier lines can
loop in & out of each socket point with the 330 ohm resistors between the
amplifier line & the headphone socket. This means that even if every socket
had a short on it you still won't blow the amplifier. The amplifier won't need
to be too large, I'm guessing about 20W per channel may do. The resistors
will ensure that the volume won't vary as the number of active headphones
changes. This is how I've seen it done before in gyms,etc.
Regards...

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestspamKILLspammitvma.mit.edu>

2000\08\10@012540 by Ries van Twisk

flavicon
face
If you don't need the 'channel' future in the your setup so people can listen to different channels i would go for a buffered situation where you have one signal wire to every headset. At or near the headset you put one of these little 1W applifiers to boost up to signal to the apropriate level.
This has the advantage that everybody can choose there own listening volume. The other advantage is that the impendance in your 'network' stays the same all the time so you don't load your 'main' source differently whenevery one connects.
This assumes that you have only one audio channel.

Ries

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\10@032042 by Jinx

face picon face
I've built a 10-set system that used a whole TL074 for each channel
of each set of phones (20 TL074s altogether). All four outputs of
each IC connect to the common speaker line by 15R resistors. The
op-amp +ve inputs were connected together, driven by a master
volume. -ve i/ps were connected to op-amp outputs, ie unity gain.
Worked great on +/-12VDC. You don't need much wattage to get a
reasonable volume

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\10@040802 by Alan B. Pearce

face picon face
My understanding of the aircraft system is the signal is distributed as a
digital stream, and when you select a channel, you pick the appropriate bit out
of the digital stream. This allows the distribution of video as well, with a
minimum of wiring (read weight) around the aircraft.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

2000\08\10@082210 by Simon Nield

flavicon
face
Andy Howard's suggestion of a digital system seems pretty sensible if you need a multichannel
system.
If you are not after particularly high bandwidth (speech only) then it's even easier, as the digital
stream won't be so fast.

For an analog suggestion I would go for one buffer amplifier driving the distribution wiring, then
seperate buffer amps at each headphone socket.
If you want to make this into a multichannel system then just have multiple buffer amps driving
different wires, and fit an analog mux on the input of each headphone buffer amp (4051 for example).

Simon

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]: PIC only [EE]: engineering [OT]: off topic [AD]: advertisements

More... (looser matching)
- Last day of these posts
- In 2000 , 2001 only
- Today
- New search...