I have an under the Table sound system I have built. I use a Lenz set -100 to run my layout and the Sound decoder. All I have is a Sound decoder in an electrical enclosure under the layout. I hook up the power wires to the Right and Laft rail wires on the DCC system and then I have 2 Speakers rated at 6 Ohms Under the layout. Now I have a Soundtrax decoder that has been working fine for about a year.
I just bought a Digitrax Sound bug which is a sound only decoder. I hooked it up to my system just like the Manual said to do. When I turned on the system the decoder Hissed. Now I assume that is the default Steam Idel noise. But that is all it ever did. Then the next night it wouldn't make a sound. I called Digitrax tech support and the guy told me I probably over drove the speakes. He said the Ohms were to low and it probably ruined the decoder?
Can someone explain what I need for speakers ? How many can I have of a certian Ohm ?? And which Ohm is best. It came with a 32 Ohm and he said it will work with a 16 or 8 Ohm. He acted like I was really bothering him and I guess I was. He probably wishes smarter people would buy there products. I am sorry but I really don't know what to do. I like the under the table sound system I have. Can anyone help???
Pat ....Indiana
Are you sure your speakers are 6 Ohms? That's not a common value at all. Most speakers are 4, 8, or 16 Ohm.
firechief811 wrote:I have 2 Speakers rated at 6 Ohms Under the layout.
Can someone explain what I need for speakers?
How many can I have of a certian Ohm?
And which Ohm is best.
It came with a 32 Ohm and he said it will work with a 16 or 8 Ohm.
He acted like I was really bothering him
Pilot is correct. An ohmmeter measures only the DC resistance portion of the speaker impedance.
That being said, it is safe to use this resistance number in your calculations since the actual speaker impedance will be at least this much and more is safe unless the mismatch is severe. (Less may not be safe.)
Also when hooking multiple speakers in series or parallel, try to match polarities if there are any markings. This is called "phasing" the speakers. In phase speakers will tend to reinforce each others sound.
Good luck,
Karl
The mind is like a parachute. It works better when it's open. www.stremy.net
Did this decoder know when you were applying throttle to commence other sounds? If all it did was idling sounds, it was working properly unless it also new that it was being called upon to produce motion sounds...chuff...turbodiesel...whatever. So, it needed an address and then it needed an input depicting acceleration and speed.
Perhaps I have not understood the question.
i'm curious how speaker size relates to all this . i'm guessing the speaker under the layout isn't the typical 1" speaker that is used with a decoder in a model train . would an 8" 8 ohm speaker work fine ? would it just be very quiet ?
He acted like I was really bothering himSounds like the Soundtraxx people. They talk down to everyone. They act like they are the only ones who know anything about sound at all. I like their systems, but getting any technical information out of them is like pulling teeth.
Sounds like the Soundtraxx people. They talk down to everyone. They act like they are the only ones who know anything about sound at all. I like their systems, but getting any technical information out of them is like pulling teeth.
you might be right about the soundtraxx people , but if you reread the original message you'll see that Pat called digitrax tech support
Yes It was DIGITRAX I talked to. And I think I see my problem. They do say six Ohm on the back of the speaker. They are cheap stereo speakers I have had for years. I have then wired in parralell. When you put an ohm meter on the total speaker terminal I get about 3 or 4 Ohms. Now I see that is was to low. I think i will just get some better speakers.
Now if I understand right, as long as the total Ohm going into the decoder is more than its smallest rating it is OK ??? Thanks for all your help folks.
Pat....Indiana
ereimer wrote:would an 8" 8 ohm speaker work fine? would it just be very quiet?
ereimer wrote: gandydancer wrote:Sounds like the Soundtraxx people. They talk down to everyone. They act like they are the only ones who know anything about sound at all. I like their systems, but getting any technical information out of them is like pulling teeth.you might be right about the soundtraxx people , but if you reread the original message you'll see that Pat called digitrax tech support
gandydancer wrote:Sounds like the Soundtraxx people. They talk down to everyone. They act like they are the only ones who know anything about sound at all. I like their systems, but getting any technical information out of them is like pulling teeth.
"Ohms" measures electrical resistance, think of a bottleneck on the freeway.
The more ohms, the tighter the bottleneck.
Split the road, so each branch has a bottleneck, you can move twice as much traffic as you can with just one branch, you halved the resistance, and halved the ohms. That road would be wired in parallel.
Put two bottleneck on one road, the traffic has to slow down and merge twice. You double the bottleneck, and double the ohms.
Now you've got the general principle, DO NOT use this to calculate effective resistance. This is for ILLUSTRATION ONLY. It's not even resistance, it's impedance, which is the same, only different. It's complicated, ok? Look up Kirchoff's law if you really want to get a headache.
Now, if traffic is too slow...well everybody gets impatient, but so what? No real problem.
If traffic runs too fast, there are crashes and burning cars, pedestrians getting run over, and worst of all the roads get torn up and the cars overheat and warp the heads and never run right after that.
Not enough ohms is traffic running too fast. Ohms are good. Less ohms are bad.
Now....efficiency.....
A fast car will make better time on a good road than on a road construction road with lots of bottlenecks. Less ohms equals louder sound. Until you have too few ohms, and blow up the car's engine. Or your decoder's amplifier circuit.
That's the general rule. Generally, huge speakers require more power to get a certain amount of sound. They move more air, they do better bass, and bass takes power. But not always. Sometimes tiny speakers have more ohms than big speakers, and an amp will sound louder with the big speaker. Sometimes, not.
AFTER you get the ohms right, then you look at efficiency. Efficiency is measured in "loudness" when driven by an amp at 1 watt, measured at 1 meter. 85 decibels at 1 watt, 1 meter is mediocre. 105 decibels at 1 watt, 1 meter is outstanding. If and ONLY if the ohms are right, then more decibles (db) are better than less.
With me so far?
Good, now lets talk about clipping.
Clipping is like when you run your car too fast and the piston rods disconnect from the pistons, break into pieces, and blow the engine block into smithereens.
Sort of.
Because when a speaker clips, it is because it doesn't have ENOUGH power, not too much power. it's pretty hard to overpower a speaker if the ohms are right. You could do it, but your talking about running a speaker rated at 10 watts on a 200 watt power amp and melting the little wires inside (called the voice coil).
That almost never happens on home stereos or train layouts. Instead, people turn the sound up too high, and the amplifier can't generate enough power to make a sound wave that powerful. Instead of a nice smooth rounded power curve, you have power that ramps up, cits off at amplifier maximum, then ramps steeply back down.
Viewed from the side, the speaker does that too. Speakers like smooth power curves, so they can flex forward, slow to a smooth stop, smoothly accelerate rearward, another smooth stop, repeat, repeat, etc.
When the amp clips, the speaker cone slams forward, stops abriptly, and then slams into reverse.
Speaker cones are made of paper.
Paper tears easily.
Over drive your amp, into clipping and you tear the speaker paper, and the speaker sound fuzzy for ever afterward.
When you turn up your amp and hear "fuzz", turn it right back down till the fuzz goes away.
Fuzz is bad.
Now you know more than the $5 an hour phone tech.
Call him back and tell him to byte one.
Guys like him give good sound a bad name.
jeffers_mz wrote:It's complicated, ok? Look up Kirchoff's law if you really want to get a headache.
It's complicated, ok? Look up Kirchoff's law if you really want to get a headache.
Good analogies and you didn't even need to cover the differential equations.
Don't forget Norton if you really want the migrane. Don't forget Fudd's first law of opposition either. It's important.