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JohnnyJ 17th August 2005 05:47 PM

Powering Crazy Car Setup In Bedroom
Hello Everyone :)

I have been thinking about what I want to do in terms of audio in my bedroom, and I decided that I will try this. I know it is a bit insane but it has been done before, and this is exactly what I want to do.

Okay so I found this other posting board (forum), and a user posted the following:

I went out and grabbed 3 lead acid car batteries from a junk yard for $5 each. They all worked enough to hold a charge and start a car.
I checked the water and electrolytes in the batteries and made sure they were up to par.
Went to a truck (big rig) supply store and bought heavy guage wire and battery terminals. They are MUCH cheaper here than at an car audio store. Compare 3 or 4 dollars to 35 or 40 for wire. I also picked up a 12 volt battery charger that had settings for "trickle" 3amp 5amp and 10amp. Total spent so far was around $65.
Set all 3 batteries on a piece of wood. Avoid concrete or carpet. Concrete is bad for the battery and carpet isn't good if the battery leaks.
Wire all 3 together in parrallel. That's positive to positive to positive to amp positive and with another (different) wire hook negative to negative to negative to negative of the amp. Now hook the charger to one of the batteries.
Use a small piece of wire to connect your "remote" lead on the amp to the positive of the batteries and your amp should start right up. Leave the changer in the trickle mode at all times and you should be able to jam for hours on end without pulling the batteries too low. When you are not using the amp remove the "remote" wire and they charge back up.

_________________, I know that it seems like a big hassle etc, but I really want to do this and need some help. If I did the same this guy did, except buy brand NEW equipment, 3 car batteries (12volt +), a battery charger [just plugged in at an ordinary house wall plug outlet], and the necessary wires/leads - would it actually work?

I have a Pioneer TS-W5000SPL Subwoofer, a Pioneer PRS-D5000SPL Amplifier and a SPL Optimized Ported Enclosure Subwoofer Box. I need to purchase: home studio speakers (x2), a car head unit and the rest of the necessary equipment to make this work. Whatever other equipment I need, please let me know.

The subwoofer is EXTREMELY powerful at 5000watt/2000rms, and the amplifier can handle a maximum of 3000watt/1500rms. This is a concern to me because I don't know whether those 3 car batteries will be feeding this amplifier/subwoofer enough power (or whatever you want to call it in the world of physics, amps?) in order to reach it's full potential. I don't want to limit my setup to perform under it's full capabilities, whether it be because of the car batteries, or whichever piece of equipment - it would suck.

Full specifications on the subwoofer and amplifier can be found here: Amplifier (Pioneer PRS-D5000SPL) and here: Subwoofer (Pioneer TS-W5000SPL)

Please give your constructive thoughts and suggestions/input, that is what I am looking for.

Thank you very much in advance,

Tweeker 23rd August 2005 02:49 AM

Stiffening capacitor(s) might be a good idea. Seen 1 Farad per 1,000 watts amp recommended by a few places (that sell them mind you). 20V+ rating is advisable. They would supply the peaks that your batteries couldnt.

I dont see why it wouldnt work.

A constant voltage/potential welder with 14VDC setting. It would laugh in your amps general direction. :att'n: :hot: :hot: :hot: :hot: :bigeyes: ;)

Basic Car Audio Electronics article on stiffening capacitors.

JohnnyJ 24th August 2005 03:29 PM

I am confused.

I need some equipment that will result in 6.5volts [maximum, and preferably] at 560amps [maximum current draw] DC input, from a standard AC house electriciy outlet. I don't have a fortune to blow in terms of cash either, the cheapest solution that produce those output results is exactly what I'm after..I just need to know what that equipment IS and how it will function!

Please help me I am getting extremely frustrated...I've been working on this for hours per day for the last week-WITH NO SOLUTION!

All help VERY much appreciated, thanks.

Tweeker 24th August 2005 06:05 PM

Er why do you need 560 amps of 6.5V? Not sure what an ordinary household outlet is in Australia, but thats 3,640 watts. With an 85% efficient converter, which is pretty good, that would be ~4280 watts and probably more VA. It would pull 19+ amps at 230V.

If your using batteries and capacitors you dont need to supply peak power from the outlet and that helps alot. I assume average consumption isnt 3kW+?

Also, do you mean a supply of +/- 6.5V?

zagisrule! 24th August 2005 06:39 PM

Why bother getting a car head unit to power your home speakers? I would assume for price reasons? Because you would get much better audio and power output from a home receiver (assuming you were not going to amplify the speakers) than you would from a car head unit. But of course, you will pay for it probably $400 or so for a CD player and receiver. If you want to really do it on a budget (and still come out better than a car head unit) I would get a cheap DVD player and a decent receiver for a total of maybe $200. You should still be able to use pre-outs on the home receiver to send signal to your sub amp.

You will also encounter another issue when you get the sub and it's enclosure inside. The boxes and the subs themselves are usually designed for a constricted volume environment in which they must produce the maximum SPL (especially on SPL equipment :) ). I would be willing to bet that once you are inside the house with that equipment, you will find it not even as loud as a simple small powered sub costing a couple hundred bucks. I have heard of people getting around this fact by installing the sub under a bed or in a closet to simulate the limited volume of a car's usable acoustic enviroment. But if you do that, rattles, size constraints, and other issues will present themselves.

I am confused as to why you need a 6V supply, all the consumer car audio stuff I have worked with needs 10-16V. I would guess that you just forgot the "1" before your 6 in your post, and you want 16V at a couple hundred amps. This is easily doable in terms of a linear power supply with or without regulation (if you can supply enough AC). The simplest thing to do is aquire a large tranformer with secondaries that when rectified will produce your desired voltage. But there we run into problems. Most common (read relativly inexpensive) toroids are up to 1500VA or so, equating to roughly 100A usable at 15V. Because I know for a fact that with normal music (not just bass sines) and listening levels and a sub enclosure that is anywhere close to optimum, you will not be coming close to 500A like you said. Another issue you will encounter is that of rectifying the output of the toroid at 100A+. It will be fairly simple because of the low frequencies involved, but you will likely still need to parallel diodes. The most daunting of all issues is getting that amount of power from a "standard" outlet. The Sorensen supplies we are using at work (1750W units if I remeber correctly) require a 20A outlet to be safe, and they are incredibly efficient switching units. You would be asking for a fire or popped breaker to plug the supply I describe above into a "standard" 10A outlet.

In the end, a standalone battery and a dedicated charger are the only economical solution. However, I will say, that it is a terrible idea to take 3 different old batteries and parallel them, that is a more logical approach than designing and constructing a line-based supply. I would use only one battery in your shoes though...too much possibility of mismatch over time with this sort of thing.

Looking at the specs on the amp, it has a max current draw of 70A (note here on a different note that it is not possible to obtain 1100W of continuous output at 14V with that spec) then we can assume at 2 ohm load (your sub with parallel voice coils) then say a max current of 150A. You don't need 500A or more if all you are powering is your sub amp off 12V.

Hope this helps a bit.


Tweeker 24th August 2005 06:45 PM

That was max current draw at 4ohm, his speaker is 2ohm.

Eva 24th August 2005 06:52 PM

That Pioneer gear is almost worthless, it's not worth the effort at all, and those power numbers are just car-audio ratings (ie: outrageous, not real).

If you want something really loud in your room, just buy some second hand PA gear (hey, it's not so crazy an idea, I enjoy a DIY three way all-horn-loaded system with a 10" midrange and a bass horn bigger than a washing machine in mine).

Tweeker 24th August 2005 06:57 PM

I think those rating are real, but bear in mind its spl comp gear, its only meant to run 30 seconds at a time, overheating is possible beyond that and they dont care a lick about distortion. Also fs is 32hz.

Eva 24th August 2005 07:53 PM

It's more like 3 seconds the time required to win an SPL contest, and blowing the entire equipmpent is allowed. It's a crazy world.

Even Cerwin Wegas and things like that are far overrated in comparison with products of other markets. I have two blown Stroker 12" here for reconing and their voice coils are similar to the ones you'll find in PA drivers rated at 400Wrms, altough these were rated at 1000Wrms. However, these voice coils didn't even had enough time to heat up and burn because the drivers are so badly designed and glued that the voice coil former broke and split from the cone and the inner spider because the materials and junctions were just not capable of whitstanding the required forces. I'm still trying to figure out how to glue the replacement cone, spider and voice coil set in a more reliable way (spiders and epoxy don't cope well).

JohnnyJ 25th August 2005 11:34 AM

No, it's voltage input is a maximum of 6.5v (it's a class D specifically for SPL designed amplifier). Unless I'm reading or interpreting the specifications wrong, I understand that the maximum voltage input is 6.5v. Some notes about some posts:

The amplifier can pump 1500RMS continuous @ 2Ohm, with a maximum of 3000watts. The sub gives out 2000rms continuous at 2Ohm, maximum 5000watts. I'm no audio EXPERT, but putting basic physics formulas into play with those amp readings, and the way that I interpret those specs, that's 70amps per 4Ohms, 70x4 = 280, times that by 2 for a 2Ohm reading and you get 560amps @ 2Ohm, which is the same reading I got from using various current calculators from sites such as Unless that reading means 70amps AT 4Ohm (and not PER 4Ohm) that would mean that it would need 140amps at 2Ohm, plus you want some leverage seeing as it's minimum 80% efficient, so add an extra 20% onto that figure and you get 168amps. However I think that I was corrent in the frist instance - that it needs about 560amps at 6.5v to power it to it's full potential. I might be wrong, but I am PRETTY sure.

zagisrule! > Remember, I need that current at 6.5v DC.. not AC... Okay so = if I bought a battery charger that charge the batteries at 6V, and I bought a Sealed Lead Acid Dry Cell Valve Regulated Cyclic battery at 12V and 28Ah, will that mean that if I connect them in series that I will be getting 6V output seeing as I'm charging the battery at 6V? Also, I could buy 3 or more of them even so that it is more stable, but I'm not sure about how I would connect/wire all those up together to give 6V output. 28Ah means that it can supply 28amps for an hour, 56amps for 30mins, 112amps for 15mins... skip through to 560amps for 3 minutes. That's right is it not? So if I got 3 of those batteries (all brand new) and wired them up in parallel, being charged at 6volts... that should work pretty well. Except, how do I get the OUTPUT from those batteries to be 6v? Will the output be 6v seeing as they are being CHARGED at that voltage, or will they still give a 12v output?

Thanks so much in advance!! I'm getting closer to a solution.

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