FALSE FINISHES

Volume, temperature, humidity among other factors all could play a role in the problem.

My recommendation is that timing wires (start or finish) should not be used for audio unless there is no other way.

Even thought they are separate wires, the become connected with a common ground inside the timer which connects the ground from your timing wire to your AC Ground to your Audio systems ground if they are both on AP. You if you have 120v leaking accross as I think was suggested that would add to the problem. An opto idolater might help as it will isolate the timing wires from the timers.
Jenna

Jenna's recomendation for keeping timing cables separate from cables for other uses is a very good one. There is not quite enough information in the other postings as to what the set-up was when the problems occurred so I will have to make some assumptions here.

Most of us most likely use some type of telephone cable for our timing wires. The twisted pairs are designed for low signal applications which works great for timing and communications applications. Reading about the problem ecountered, it sound like high power audio was sent in the same cable as the timing pairs. With high power audio in the same cable you could get weird things happening as it sounds like occurred here. Usually if you are going to run audio on telephone cable pairs, it must not be at the high power level but needs to be changed to a 600 ohm impedance which is at a much lower level and generally isolated. Many good paging amplifiers will have a 600 ohm output to feed other amplifiers. If the amplifier does not have a 600 ohm output, you can purchase adapters to get you to the 600 ohms needed. At the other end you need another amplifier to power the speakers or use amplified speakers/horns. Most paging amplifiers will have a TEL/Line input so no special adapters are generally needed at the remote end. Yes it is a bit more expensive and AC at the remote end could be issues but this setup should eliminate the problems described.

I would say it comes down to several options here. One would be to install a second cable along side your timing cable and use the second cable for just audio. Another option would be to install a second amplifier at the remote ends and send low power audio in the same cable as your timing pairs. Unfortunately a good paging system isn't much cheaper than a good timing system but when both work great, you are a hero.

Rib Mtn Timer is mostly correct however the end goal can be done. I suspect the assumption about sending high power audio on the same cable as timing power is right, but lower level (70volt) on the same cable may be possible.

I have seen 70volt systems work on the same cables as timing wire with Horns used for announcing (good for voice, not for music) that was plenty loud without re-amplification. Dartmouth Skiway's system works like this pretty well.

There are other systems out there that send sound a long distance without using re-amplification that use transformers at the speaker end, but these generally are much more expensive and custom built.
Jenna

We use separate cabling in our race hill setup at Bear Creek. We have 2 inch conduit from the top registration building where the upper sound system amp is located to the finish.

From the Registration Building to the Finish Bldg:

2 - Belden 2200 shielded microphone cables for audio "line level" from bottom mixer to upper amp. We use a Fender powered mixer/amp with 2 speakers on tripods at the start.

2 - Cat 5 cables

That conduit joins the main line out near the start ramp.

Start Ramp to Finish

2 - Belden 2200 lines
2 - Cat 5 lines
1 - 4 pair timing line that is terminated with banana plug panels at the start, intermediate point and at the finish line. We were going to put 6 pairs in but the area had this nice 4 pair 18 ga cable surplus from an electrical project that we used instead.

We use 3 lines for timing. We have to use a separate headset line due to data noise (like everybody else)

Our sound system at the finish uses a Soundcraft mixer, Crown Amp, and DBX processing.

All of the connections on the hill are soldered, shrink tubed, etc. We drove a mule with a generator along side the wiring and did it all in one day.

We actually use wireless for the finish line now. Our hill sets up differently due to the snowmaking and grooming. It is easier to use the wireless and move the finish up the hill for the J5 training races than anything else. We use ALGE TED 10tx transmitter with a special dual course break out cable to send signal from the cells that we happen to be using to the timer.

We had this debate a couple of years ago at Gore Mt. The ski club wanted to install speakers most of the way up the hill for coaches, etc to hear the announcer. We have a 12 pair, 18ga solid gel filled, direct burial wire running all the way up the hill. Since I only use a few of the pairs at any race and there are lots of extra pairs, the thought was to use a couple of pairs to drive the speakers. (Even for blind finish races I use only 5 or 6 pairs - 2 start, 2 finish - 2 comm.) After seeing this done at another area, and the subsequent related problems, I convinced them not to do it and spend the money on another wire.
We ended up running 4000 feet of 14/2 direct burial romex wire. (Overkill, I konw but it was 4 years ago and copper was much cheaper then. It cost about $150 per 1000' roll) We have 7 Bogen speakers on the hill, each with individual shut off switches installed at the base of the trees they are mounted on. These speakers run in 70v mode. The amplifier has outputs for both 8 ohm and 70v so there are matching transformers on each end. The system plays music OK, as long as you keep the volume down, but can blast voice across half the mountain if we want to. Its great for getting announcements to the racers and coaches while they are inspecting. The Bogen speakers are pretty expensive. About $125 each. We already had the amplifier. Best of all, there is no conflict with the timing system.

I corrected my post from 70 ohm to 70 volt (my memory failed me), but DG is right.

I don't think $125 for a speaker is a lot at all, not when a photocell mount costs $50. Its the cost of three new gates but they should last 5-10 years or more if you bring them in each summer and well worth the investment!

Jenna

Fred's set-up sounds nice and DG1 system sounds great too. Yes there is a 70 volt system and that is what we use at our hill for the horns at the finish area. Most paging systems use either 25 volt or 70 volt systems. When I use to install comercial sound systems, the 70 volt cables were always run along side the telephone cables and we never ran 70 volt on the telepone cable themselves. If you needed paging in another location, a 600 ohm feed was taken off the main paging amplifier and then run on telephone cables. Another amplifier was installed at the remote location with it's own 70 volt system. There are paging horn out there that will take the 600 ohm input directly and the horn has a built in amplifier that uses a 24 volt power supply.

Yes you might get away with running paging in the same cable as with your timing but it is not a good idea.

Steve

The other thing to consider if you are going to consider 600ohms is a powered speaker thta takes digital or analogue audio. There are many powered speaker options now that take digital or analogue audio over a single pair of wires or digital over cat 5. The speakers are generally bigger and few of them are rated for outdoor use but they certainly would allow music. You would need power (120vlt) at each speaker but very little or no pre-amplification. This would work well for an area that has power up and down their run, maybe from lighting.
Jenna