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 Post subject: Passenger car public address sytems
PostPosted: Wed May 30, 2018 2:45 pm 

Joined: Sun Aug 22, 2004 11:06 am
Posts: 476
Location: NE PA
What works and what doesn't? We are looking to start from scratch on a passenger car public address system and want to know what everyone uses and learn from other's mistakes as well as successes. The maximum train length will be around 12 coaches. Thank you in advance for your input.
Mike Tillger


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 Post subject: Re: Passenger car public address sytems
PostPosted: Wed May 30, 2018 3:05 pm 

Joined: Mon Aug 23, 2004 9:37 pm
Posts: 251
Location: Niles Canyon Railway, near Sunol, CA
System requirements include:

Not all cars need the same volume from the speakers. Each RR car should have an easy way (ideally a knob located where a short train crew member can reach it) to adjust loudness / volume for that car, including an "off" position, or an on/off switch.

Car-to-car connectors, if used, should pull loose from car ends without self-destructing. (Sooner or later a brakeman will forget to uncouple the connector cable when uncoupling cars.)

- Doug Debs


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 Post subject: Re: Passenger car public address sytems
PostPosted: Wed May 30, 2018 3:39 pm 

Joined: Mon Aug 23, 2004 12:53 pm
Posts: 187
Location: Manchester, NH
We don't use one on the WW&F. However, I was visiting Downeast Scenic in Ellsworth, Maine this weekend and was impressed with the clarity of their system. It was also rigged to a GPS so that a pre-recorded narration played automatically during the journey.

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Please help the WW&F construct a Narrow Bridge Ahead!


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 Post subject: Re: Passenger car public address sytems
PostPosted: Wed May 30, 2018 4:04 pm 
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Joined: Thu Oct 08, 2015 11:54 am
Posts: 256
Location: Orrville, OH
Each of our cars were done old school. Each car had it's own PA system and they were also daisy-chained back to a master station in one car in the center of the consist for general train-wide announcements or background music when required. We did that with 5 to 7 cars. If you go with one PA amp for the whole consist, see if you can go for 70v line out with audio transformers in each car. You can get the analog signal farther that way. We also had a parallel video system for safety and educational videos or for a "view from the front porch" of the locomotive.

At one time, I was working with a commercial audio/video company to replace all the analog equipment and come up with one expandable, fully digital system that could do both audio and video without having to worry about analog signal quality or loss. It became a moot point when we exited the excursion business. I'd suggest that you give that a shot if you're considering video also. Digital packets of data will travel better down a long wire and the little boosters and converters aren't all that expensive.

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 Post subject: Re: Passenger car public address sytems
PostPosted: Wed May 30, 2018 5:11 pm 

Joined: Mon May 24, 2010 10:22 am
Posts: 465
Back when I was helping doing excursions with mostly rented cars, a couple of us came up with a design for a portable train PA system.

The idea was to take a plastic toolbox, mount a couple of PA speakers on the toolbox and put a radio receiver, amplifier and battery in the toolbox.

We planned on tossing one or two into the luggage racks of each of the cars, securing it with a bike lock.

Then when someone needed to make a announcement, they could turn their radio to "channel B" and broadcast to the whole train.

-Hudson


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 Post subject: Re: Passenger car public address sytems
PostPosted: Thu May 31, 2018 2:01 pm 

Joined: Mon Aug 23, 2004 12:08 pm
Posts: 255
Location: Western Railroad Museum - Rio Vista
I would suggest using a 70 volt PA system on the train. Each loudspeaker will need a transformer to match voice coil impedance to the 70 volt feed. These transformers are fairly cheap (typically about $5 each). On Niles Canyon Railway we power 15 car train PA with one 70 volt PA amplifier. Each car has a minimum of six loudspeakers. We use 1/4 inch stereo headphone plugs on jumpers between cars. If a brakeman forgets to unplug a car when switching, plugs pull out with no damage. Sockets on ends of cars are parallel with rails.

A basic problem is children who don't want to listen to the PA system competing with the PA system by talking loudly to each other.


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 Post subject: Re: Passenger car public address sytems
PostPosted: Thu May 31, 2018 3:35 pm 

Joined: Thu Feb 26, 2009 3:07 pm
Posts: 473
Location: B'more Maryland
Just throwing ideas out there, but what about wireless?

If you have 110vac in your cars, you might be able to use a system like Sonos.


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 Post subject: Re: Passenger car public address sytems
PostPosted: Thu May 31, 2018 7:20 pm 

Joined: Sun Apr 02, 2017 3:13 am
Posts: 19
We use the same plugs you use for 6x4 box trailers towed by cars. They won't withstand a rough shunt, but they are weatherproof, readily available and easily replaced.

If I was starting from scratch, I'd certainly look at bluetooth or wireless, battery powered equipment and have no wired connections between carriages.


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 Post subject: Re: Passenger car public address sytems
PostPosted: Thu May 31, 2018 11:03 pm 
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Joined: Fri Oct 24, 2008 9:05 pm
Posts: 710
Location: MA
kew wrote:
We use the same plugs you use for 6x4 box trailers towed by cars. They won't withstand a rough shunt, but they are weatherproof, readily available and easily replaced.

If I was starting from scratch, I'd certainly look at bluetooth or wireless, battery powered equipment and have no wired connections between carriages.


Bluetooth has problems reaching 20 feet never mind a whole train


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 Post subject: Re: Passenger car public address sytems
PostPosted: Sat Jun 02, 2018 9:13 pm 

Joined: Thu Feb 03, 2005 9:32 pm
Posts: 256
If you already have 120v power in every car small separate amps or a wireless system makes some sense. But being familiar with 70 volt systems, they are the old bulletproof standby.
One pair of wires from the amplifier with 70V output. Then however many speakers with the 70 v transformer attached in parallel as you need. Two to four per car is a rough guess, cube types staring around $40 or so. Each speaker/transformer has a tap or switch to vary the loudness of that speaker as needed.
Bogen has a design PDF if your interested in details.

http://www.bogen.com/support/productcat ... ysDsgn.pdf


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 Post subject: Re: Passenger car public address sytems
PostPosted: Sun Jun 10, 2018 2:06 pm 

Joined: Sun Aug 02, 2009 10:23 pm
Posts: 8
At Monticello we use a 70v mono PA trainline with (currently) a single 300w amplifier (a JBL CSA1300Z); this handles 7 cars with 24 speakers so far. The PA trainline is 12 gauge copper wire, and we use heavy-duty 1/4" phone plugs for between-car interconnections. This is not remotely weather-proof but has not been a problem so far in the last 15 years.

Each car has an autotransformer which can locally attenuate the volume in that car (Atlas AT100 or equivalent).

We use mostly JBL speakers; most of ours are the (now discontinued) surface-mount Control 23T; we've also used a number of the 24CT Micro / MicroPlus when they'll fit into existing speaker boxes on the cars. In our ex-Wabash coach 1827, the speakers are mounted in the air diffuser with only a few inches of height available; we used the ones that were already in there when we got the car and they sound pretty terrible. Replacing those is a project which needs to happen pretty soon.

All of this is fairly overkill for general PA announcements, but since we do Polar Express we need to be able to play fairly loud music and have it sound good. The sound for Polar is mission-critical; we have a backup amplifier and several spots in the cars where we can plug an amplifier into the system (again, via a 1/4" phone plug).

For reliability I would recommend against wireless. One advantage of a single- (or few-)amplifier system is that by putting a UPS on the amp and audio feed equipment your whole PA system can keep working through any HEP or local power glitches; again, important for an event like Polar.


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 Post subject: Re: Passenger car public address sytems
PostPosted: Tue Jun 12, 2018 9:58 pm 

Joined: Thu Nov 22, 2007 5:46 am
Posts: 2488
Location: S.F. Bay Area
Ed Kapuscinski wrote:
Just throwing ideas out there, but what about wireless?

That's tricky. Wifi doesn't just want to propagate down a metal train, it may take some clever arrangement of repeaters/bridges to bounce it down the length of a train. Should be possible though.

Bluetooth is out of the question, unless you are only using it to leap 6 feet across couplers.



Quote:
If you have 110vac in your cars, you might be able to use a system like Sonos.

May not even need 120VAC. Most tech gadgets actually run on low voltage DC internally, and use external, commodity
"wall wart" power supplies to convert mains to their working voltage. Often 12VDC.

Partly because it's MUCH easier/faster to clear a UL listing for a low-voltage device. Even if their wall-wart is a custom job like Apple, they can design the wall-wart very early and have it already through UL when the tech is ready.

So it may be a simple matter of a DC-DC converter from car battery voltage. Those are sold by Mouser, Digi-Key or other electronic suppliers. DC-DC have a standby power cost, so feed them through a 12-hour Intermatic rundown timer.

Also remember my trick with the solar panels, been going 5-1/2 years strong with zero maintenance except replacing glazed plexiglass covers at intervals.


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