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The Basic Stereo Explanation Wanted

Old 11-13-2008, 04:06 AM
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The Basic Stereo Explanation Wanted

Hi everyone,

My name is Tom and I started a party bus company 6 years ago. I have taught myself how to paint, fabricate seat, and do upholstery.

The one thing I do not know how to do is --> the stereo system set up.

I would appreciate an explanation of how a stereo gets set up, what components are involved, and how things work.

I realize this is very basic, so your patience is appreciated.

To the ambitious and eagers ones who give me lots of detail, thanks in advance.

If you want, I can also arrange to receive a diagram as well.

Thank you very much.
Tom
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Old 11-13-2008, 05:49 AM
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First, determine your needs. Stunning SQ (sound quality) or knock your socks off rattle and roll. Big difference.

First (A), budget. Seriously. For a large bus, 2k to 50k plus with video, etc, etc.

Lets pretend we are talking about a car here. All reference to watts (power) should be in RMS (Root Mean Square) everything else you can pretty much ignore. RMS is what counts.

The BASIC idea is Head Unit (The in dash "radio" part).

Door speakers, either coaxials (woofer/tweeter together) but better to go with components which are seperate mid bass, tweeters, etc. Individual speakers more or less.

Amplifier for the door speakers or components. 2 channel for 2 speakers, 4 channel for 4 speakers. Head units (GENERALLY) blow hard for power and will not provide anywhere near what an amplifier will. Say a couple hundred watts easy.

Subwoofers are next. They produce the loud, low tones that a small door speaker has no hope of reproducing. Sky is the limit here. 10" 12" 15" 18"
1-2-3-4 whatever you want.

Amplifier for the subs. We are talking a THOUSAND Watts RMS for 2 subwoofers easily. You can go lower, you can go higher, but its best to match your subwoofers with the correct amplifier AND THE CORRECT SUBWOOFER ENCLOSURE (or box).

I have left out so many, things (tired) that my answer is almost useless, but learn as much as you can, read, read, read, then ask questions.

Congrats on the business... It aint easy.

Cheers

John
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Old 11-13-2008, 08:52 AM
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To elaborate on what John was saying...

You could get a powerful enough four channel amp to sufficiently supply power to 8 or 16 speakers, 4 or 8 per side of bus. You could wire 2 or 4 speakers onto each channel. I'll draw a diagram in a minute. I believe it may be a more efficient way of filling that bus with sound. Instead of buying 4 speakers and trying to put copious amounts of power through them to achieve the volume you'd need, 8 or 16 well powered speakers may end up lasting longer.

Then get two or four 10" or 12" speakers in a proper enclosure, with sufficient power and you'd be in good shape.

But like John mentioned it really comes down to budget, and whether you're trying to achieve quality, or quantity. I would imagine that shortly after your clients have boarded they're too intoxicated to really appreciate a system built entirely for high-quality sound. Volume and bass is what'll impress them.

Rockford Fosgate: T8004 800 Watt 4-Channel Amplifier (200W x 4 @ 1-Ohm RMS) or (400W x 2 @ 2-Ohms bridged RMS)

Boston Acoustics GT42 (120W x [email protected] 2-ohm) or (350W x 2 @ 2-ohm bridged RMS)

Hifonics Zues ZXi 8408 880-Watt A/B-Class MAP: $ 729.95 (220Watts x 4 @ 2-Ohm RMS) or (440Watts x 2 @ 4-Ohms bridged RMS)

MB Quart RSI 216
6-1/2" 140W Component Speaker System



So speakers 1 through 4 are on the front bridged channels. And 5 through 8 are on the right bridged channels, in this diagram. The speakers you're going to get are most likely going to have an impedance of 4 ohms. If you wire speakers 1-2 and 3-4 in series, each pair will equal an 8 ohm load. When you wire the pairs in parallel you'll bring the resistance back down to 4 ohm. Having said that, if you were to use the Hifonics Zues ZXi, since you've bridged channels you'll supply the rated 440W to the 2 channels you created. Since you have four speakers on each of those channels, the power is divided evenly between them, giving each speaker 110Watts.

In this picture you're utilizing all 4 channels of the amp. Each channel has a pair of speakers wired in parallel on it. A pair of 4ohm speakers wired in parallel puts a 2ohm load on the amp. In this case you could use the Boston Acoustic amp which will provide 120W per channel with that 4 ohm load. That 120W would be shared between the pair, giving them 60W each, which is 3 times what a decent head-unit would be able to provide.

Anyway, that's a good place to start. I'll help out as much as I can.

Good luck.
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Old 11-13-2008, 09:36 AM
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To join in with John and TragicMagic - you will also need to consider wires, and power supply.

Everything runs off the 12V electrical system in the bus. You should consider upgrading the battery (potentially adding 2, 3 or more additional battery's) to something like an Optima Yellowtop battery. Consider also upgrading the alternator to a high-output alternator - you've got the room in the engine compartment, make use of it!

While you are working under the hood, you should beef up the main electrical wires that connect your battery, alternator and ground to the chassis (also known as 'The Big 3.' Increase these wires to 0 AWG or 0/1 AWG. The wires are: 1) Chassis (ground) to battery negative, 2) battery postive to alternator positive 3) Alternator negative to chassis (some consider this last one unnecessary as the alernator is bolted to the chassis, but it is always best to find a clean bare part of the chassis to ensure maximum current flow). If you decide to use multiple batteries, connect them to each other with the same big gauge wire - all the positive terminals connected, then all the negative terminals connected.

With those upgrades in place you then bring the power to your amplifiers. use the same guage wire. Within the first foot of wire you will need to place a fuse - the fuse protects the whole buss from an electrical fire in case of a short. If the bus is involved in an accident twisted metal can very easily slice into a power line causing arcing and a fire - fuses prevent that. Chose your fuse size based on the total of fuses on all of your amps (Two amps with 40 A fuses + one amp with three 30 amp fuses = 170amps) and you can round up from there - and get a 180 amp or 200 amp fuse.

After the fuse the power wire will run through the firewall into the bus cabin to a fused distribution block. Here the wire will be divided and sent to the individual amps. If you have 4 amps, you will want a block that receive one big wire from the battery, and connect 4 smaller ones to. Again, each independant line shoud be fused because the wire size has decreased (this is like the fuse panel in your house - big main breaker, lots of smaller breakers for individual circuits). Again, the individual fuse for each line should be a close match to the fuse rating on the amp.

Depending on the power each amp draws you will need a smaller guage wire - most amps are 8 - 4 awg, but there are monster sub amps that require bigger wire yet. Use the awg wire for both the + and - on the amp. Be sure when connecting the amp - to the bus ground that you find a clean, unpainted section of metal - sanding/grinding will likely be required. Any dirt, grease or paint will inhibit the flow of electricity.

Besure that when you connect everything that you leave the BIG fuse under the hood to be the very last item that you connect. Installing the main fuse any earlier than last is dangerous because when you are working with the wires there is a danger of accidentally crossing the wires and causing a short.

One other item - each amp requires a remote turn on (you can use a small wire for this 18awg or so). Most Head units have a remote turn on line . . .however it is not adviseable to connect more than 2 amps this line as it has limited current capacity. Instead, if you are connecting multiple amps, be sure to use a relay. That way the relay is the only thing drawing current from the head unit, and when it turns on, it sends 12VDC from another source (like a fuse block) to all of the amps . . . then you can connect as many amps as you would like.

Ask questions as you go, and we'll do our best to help you out
Ryan
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Old 11-14-2008, 07:33 AM
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Not sure how your bus's floor plan is currently laid out, but it would be wise to keep the amplifiers as close to your engine compartment as possible. That would enable you to keep the lengths of the power cables as short as possible, which accomplishes two things. More efficient power supply, and less cost. Of course, you'll need longer run of speaker wires, but that should be less expensive wire.

I also had a thought about your subwoofer enclosure. You could get creative and incorporate the box into some sort of seat/piece of furniture. Again, I don't know how much room we're talking about here. But having a few subwoofers could take up a little space. Of course, I'm thinking way too far ahead.
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Old 11-14-2008, 09:04 PM
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To make your life simple, if we are not talking video, or subwoofers, or enclosures, etc, I have seen on line many self contained speaker cabinets, maybe the size of a Kleenex box with a tweet and small mid in them. They come with a U shaped mounting bracket.

A lot of these are fairly decent quality, steel housing, etc. You could take Tragic's drawing up above and mount 8 of them up near the roof line (out of harms way). With 1 or 2 amps I'll bet the output would be more than enough for the listening area.

Inexpensive, dead nuts simple, clean looking, loud, did I mention inexpensive?

You haven't checked back lately, so I would guess you're hard at work making money, but let us know whats going on, and what your budget / space limitations are.

Cheers

John
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Old 11-15-2008, 12:18 AM
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Hell, they wouldn't even have to be car audio speakers. The speaker style that John is talking about would be easy to find in home audio speakers. The impedance of home audio speakers is usually 6 ohm minimum, but more likely 8 ohm. That would make wiring really easy. Connect all the positives to positives, and negatives to negatives on each channel (wiring in parallel) would bring your final impedance to 2 ohm. Then getting an amp that's capable of producing enough power for all those speakers shouldn't be too difficult, especially when its running at 2 ohm.
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Old 11-15-2008, 06:08 AM
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These are the kind I was talking about, about $150.00 a pair, but you could go lower or higher. These happen to be indoor / outdoor. If you put 50 watts to 8 of these, then a 600-800 watt amplifier would leave you room to spare and could be picked up used for a few hundred.

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Old 11-18-2008, 09:37 AM
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This is an amazing set of explanations and I am truly over-whelmed at the time you all have taken to explain this to me. Thank you so much!

I do need to learn about the sound of the vehicle and how all that works, but the next one that I build will be decked out with video and other equipment. Essentially, I want to build it so it has the ability to advertise anything at the touch of a button. Videos, signage, etc. of products that I have sold advertising for.

That is the big picture, but I think I am off to a great start!

I will message you each individually shortly with my thanks and questions!

- Tom the Party Bus Guy
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Old 11-18-2008, 09:43 AM
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Reading John's posts there, the space I have in the bus is a lot given they are built 35 feet long and 10 feet wide.

However, we now have to consider the seating capacity, the movement and dancing of the people on the bus, and the windows. So I don't really have an answer for you.

When putting in speakers, is there anything wrong with doing it lower than head height? What I was just thinking is --> could you build an upholstered handrail and then build the speakers into them? Would this affect the sound quality?

If we went this route, we would not have to worry about what we do or do not have "space-wise" in the bus up near head height.

We also need to keep in mind that people get wild on my buses and we need to hide anything that can be broken. Therefore, its always good to have something protective in front of them.

Write me back what you think fellas.

Thanks again.
Tom
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