Stereos & Batteries - Read before buying.

[alwaysredee]

I love it! I used to steal that stuff back in the day! Rock on and keep the spandex! It insulates well now that we're older!

 

[alwaysredee]

I used to steal that stuff back in the day! Rock on, brother! Keep the spandex for underwear, though! Insulates well!

 

[B.G.R.]

Charging parts on the way! Found all the goodies for 200 bucks. It matches the 40 amp system now. Fire in the hole.

 

[JW]

I did notice some rather vague applications of Ohm's Law. Remember, if you raise voltage, you lower current, at least on this planet.

Actually....

Depends on the circuit. You're 100% correct if your circuit has a regulated power supply. More voltage = less current in most units. This is true of all stereo amplifiers and head units.

Now, if you have a simple circuit with no regulation, then more voltage will result in more current. Very simplified example: A battery wired to a resistor (such as a light bulb), then back to the battery. The higher the voltage supplied, the more current you'll have running through the circuit. In this case, the voltage drop across the resistor will increase to equal the input voltage.

 

[Jimway]

Hi JW, Jimway here. I respectfully request your permission to pick out the part about me being 100 percent correct. May I say that I like the way you think. You have made my day, For some reason, I don't hear this kind of talk as much as I would like. Now for the voltage drop across the light bulb part. Is this where the light bulb goes from a dull red to a bright blinding white right before darkness happens? I have seen this happen in the past.

 

[JW]

Depends on the light bulb

Better to use a resistor as the example though, because electronics geeks like me also know that the resistance of the light bulb goes UP as the voltage goes up, because the filament gets hotter, so that kinda throws the calculations for a loop.....

So for all non-electronics geeks, Ohms law simple circuit: E = I * R.
Where E is voltage
I is current
R is resistance.

Example 1: 10Vdc = 1 amp * 10 ohm.
Example 2: 20Vdc = 2 amp * 10 ohm.

That's simple circuit. Most 'boxes' or 'units' have a regulated power supply and are made up of hundreds of individual circuits, so you have to break down each circuit in order to apply Ohms law. The purpose of the regulated power supply is to supply those hundreds of circuits with the same voltage despite the input parameters, up to a limit. That's why, when you supply more voltage to a 'unit', the current draw will go down. And vice-versa. Up the voltage to a regulated power supply, and it'll compensate by reducing the voltage within itself, so the circuits it feeds are fed the correct voltage. This reduction results in lower current draw from the outside source.
Lower the voltage coming in, and the regulated power supply will compensate by upping the voltage inside itself by drawing more current to compensate, so that the circuits it feeds can maintain the correct voltage.

Our boats and cars are really missing out compared to the aircraft I work on We operate our components off 24Vdc batteries. When the aircraft are powered up, we actually have ~ 28.5Vdc for our components. Twice what we get from a powered up car or boat. With 28.5Vdc to play with, our components can draw less current.

 

[rhino1653]

I got about 5 key strokes into the explanation you typed J.W. but then I remembered how my recent attempts at humble correction went, so I let it go. On a side note, what kind of aircraft do you work? I'm in the same field. I do Electronic Warfare systems work on E-3's.

 

[thaphillips]

You could run the four highs
(4 ohm) speakers in parallel and get a dual voice coil sub (4 ohm). There you go by wiring the highs in parallel it will drop the 4 ohm speakers to 2 ohm thus doubling the wattage. By getting a DVC (dual voice coil) sub you could hook it up to the two left over channels. The sub would run at 4ohms.


So four speakers in parrellel on channels 3 & 4. The one DVC sub on channels 1 & 2. So six speakers. I think most people here would be happy with 4 speakers and a sub.

After re-reading this the 4 (4ohm) high speakers should be wired in series parallel to channels 3 and 4 bridged. I believe that should be 2ohms.


and the Dual Voice Coil sub could have one voice coil run on channel 1 and the other voice coil ran on channel 2.

Does this make sense?

 

[thaphillips]

All true, and I wanna apologize for my part. Maybe I didnt exercise the best tact in the my replies. I tried to delete my recent messages, but could only delete the last one. Moderators, feel free to eliminate the argumentative stuff. It's apples to oranges, and everyone will have different opinions. Maybe if ThaPhillips is still checking the thread, we could amend a few things in his original posts and make this an audio sticky. Might avoid alot of questions.

Sorry for arguing as well. Unfortunately it doesn't let me edit my posts now, so I can't amend anything in prior posts.

 

[ezflyer]

Sorry for arguing as well. Unfortunately it doesn't let me edit my posts now, so I can't amend anything in prior posts.

glad to see yall could make a mend. we should all respect one's opinion with out disrespecting the others. it is hard to do at times. it mostly depends on how you word something. a little thought can go a long ways when replying to a negative feed back or post. i have learnt that if i dont have the facts, i dont post. i have made my self look like a real ass by speaking out of turn on something i dont know all the facts about. i used to do stereo hook ups when i was younger. i have learned even more in this thread. i must thank all of you for you feed back. i also have learned from other people's mistakes. probly the most important task i ever learned. i am fixn to hook up a stereo system in my bass boat for when i take the kid's and wife out. i will refer to this thread so thanks for all who posted good or bad.

 

[stapletm]

I agree, great thread for reference material, thanks guys. One question that didn't come up - What direction should a sub be mounted to give the optimum output, cone up???

 

[sim]

I agree, great thread for reference material, thanks guys. One question that didn't come up - What direction should a sub be mounted to give the optimum output, cone up???

When you say optimum do you mean greater output (db) or greater clarity and precision?

 

[stapletm]

Genrally?

 

[fireguy]

Generally it wont matter which way the driver is facing, depending on the type of enclosure. Sealed would be preferred in the marine environment. There are gobs of subs out there that perfrom very well with front firing, side firing, and down firing driver placement.

What will be more important will be the sub (enclosure) placement. This could have much more impact on the subs performance. If the sub is located in the cockpit then facing into the cockpit may help. If it is in the cabin (like Noyzee's, ??) then you may get some cabin gain like you get in a car. He says he gets great performance out of his.
If you can place the enclosure where the low frequency sound waves have a bit of opportunity to bounce off an adjacent surface then this my help you achieve a little "cabin gain".

 

[stapletm]

thanks. I have an open bow Eluder, no cabin space, but there is a big space above the passenger's feet wich size wise seems ideal for a fairly square sealed sub box. From that loaction though, the only mounting direction I could use is ponting down, at the pasenger footwell? Wasn't sure about the mounting down facing aspect, or the location, given that it would be directing down into the carpeted floor?

 

[fireguy]

Shouldn't be that big of a compromise, especially if tha tis the only place it can go. The down firing driver shouldn't matter, although some say down firing makes the surrounds and spiders wear out sooner.

The carpet should not matter much because of the length of the sound waves. Bass frequencies have really long sound waves and are much harder to absorb than higher frequencies. Carpet and padding isn't super effective at absorbing frequencies anyway, unless you are talking about a completely carpeted room vs. bare floors in a house.

 

[zcausey]

What type of system setups are you guys running? like rms wise and size(8,10,12s) etc. Me personally if im going to do a system in my predictor I am thinking atleast 500 rms watts total...