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I tried connecting my 12V lead acid battery to my 2005 model PowerAcoustic amp. My multimeter indicates it is getting power. I touched the leads to the terminals on the amp. At a 20V setting on the multimeter, it reads as 11.93.
The amp does not turn on. The power indicator light does not ignite. I have no idea why not. I checked the wiring, it is correct. Inverted the wiring and blew the fuse. I replaced the fuse, still nothing. So I figured the amp was dead.
I purchased a brand-new amp, but the same thing happens. I connect the leads, the multimeter indicate power on the amp terminals, but it won't turn on.
Does anyone have any idea why this might be happening? 

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Car amps have a switch line in addition to pos & neg.  You can probably just tie the pos and switch terminal together with a wire and then it will turn on whenever you supply power.

The point of the switch terminal is that you can leave the amp connected to power but when you turn the ignition key the amp will switch on.
What Todd said.

The "switch line" is usually labeled "remote".

I just treat it as a second positive when I wire up amps-- one negative and two positives.

Thank god for fuses . . .

Thank god indeed, and thank you gentlemen! Your solution worked. I have two amps and I intend to use them both. :)
Glad to hear. Where are you at with the speaker conundrum?

The speakers proved inadequate to the task at hand, as you likely know. I still have them, but three of the four are dead. If I could clear out the cones and replace them, it might prove a worthy endeavor one day, but I can't begin to figure out how to dismantle this wood without destroying it. Everything appears to be tightly glued together, no screws to unscrew.  


I have managed to procure these:


They have been tested on both amps and seem to have the power needed. Reviews indicated their ability to push out bass was their strength; my new Pioneer amp has borne this out better than the PowerAcoustic. I haven't tested them outdoors yet, blarsted rain. 


I also have a set of these on the way.


Based on research my hope is that they will offer better sound quality at the high end. 


My old sealed lead-acid batteries from 2005 don't seem to hold much of a charge anymore (this is normal, right? Especially since they have been more or less sitting around the house unused for years), so I invested in a Shorai 18Ah 2lb. battery. It should arrive midweek. 


My original plan was to test both sets of speakers and return the lesser pair (or the more expensive one, had they proved comparable), even though in my heart of hearts I wanted to run systems at both the front and back ends of my bike. Now that I have two amps, the temptation to add a second battery to complete set 2 will likely prove overwhelming.


I don't know if I want to spend the big dollars on a second 18Ah battery, but perhaps this is necessary? I would be interested to know your thoughts about this. I recall you telling me once that a lower-power battery will likely yield lower-power sound? I would probably like for the sound at both ends to be close to balanced. 


There are particular goals that are unique to my situation. First, H, you in particular might remember that I built a beautiful trailer in 2005, but had to get rid of it because I lacked storage space. A trailer isn't on the menu for me. My bike has heavy-duty racks on the front and back for cargo and I would like to attach my system to that. Size and weight is a particular concern, since I will be pedaling to events from the suburbs. If I have to compromise power or sound quality, so be it. 


The speakers are housed in plastic and are weatherproof. My rig will likely not be used in the winter.


In addition to my 2005 model PowerAcoustic 120W amp, I now have this larger-than-expected, heavier-than-expected beast:


Any thoughts, particularly about the second battery? I will likely order one tonight.   

One 18 aH Battery can power both amps. You may be underestimating how heavy it is.

Less battery headroom translates to poorer bass response, and vice-versa.

As you've discovered most amps are not built to be light and compact-- in fact they add unneeded extra weight and size as a selling point to "average" car audio consumers.

If you would slow down a bit we could have pointed you to the amps Todd's using for his portable system:

I have the 2-channel version which I have tested but have not got around to setting up in a finished system.  2 12aH batteries in series (=24v) would be about right to power the 4-channel-- I plan to run mine with two 7aH batteries in series.



I will admit to feeling a bit under the gun about this. I have a friend coming from out of town this month just to ride in the mass with me. I was hoping to have a system assembled, tested and ready by then. 


My concern about using only one battery is running a cable from one end of the bike to the other. Last time I did that with a sound cable, it got pulled and caught in the workings of the gears, and subsequently destroyed. For that to happen with a power cable, I imagine such a thing could be very nasty, even potentially dangerous. I do plan to run one sound cable from front to back for the iPod. It is a coiled cable, like the one that ran from the handset to your old landline phone.


I saw that amp board or something similar in Spencer's shopping list thread, but I probably misunderstood how they work. It would be great to have Class D, but tough to find the time to assemble something or to figure out what the appropriate way to assimilate that into my system might be. I might ask Todd to show me how he has built those in before/after the next ride.


It might be more complicated for me to mount those boards and carry them without a trailer (or not). Instead of plywood, the foundation of my system will be heavy-duty plastic crates. I will likely incorporate some wood to secure the amp and battery to the crates. Not sure yet. 


It says here the battery weighs 2.12 lbs.?

 I just ordered a second 12aH battery, based on your suggestion, H. As i wrote above, it feels more like a safety issue than ensuring adequate power. Hopefully it will prove adequate to the task.

My suggestion was that the 18 aH battery you already have would be enough for both amps.

An 18 aH and a 12 aH is a large amount of weight to carry on a bike unless you have some sort of custom rack setup like on Alex's cargo bikes.  I hope it works out anyways.

I cancelled the order for the second battery. Shorai has been so busy filling back orders that they had not shipped either one until Thursday. My 18aH one and charger should arrive tomorrow. 


Tonight someone suggested that using my one 18aH battery to power a (2x180w speakers + 760w amp) + (2x350w speakers + 120w amp) system at a loud volume would result in about half an hour of playing time. Is this a concern?

H3N3 said:

My suggestion was that the 18 aH battery you already have would be enough for both amps.

An 18 aH and a 12 aH is a large amount of weight to carry on a bike unless you have some sort of custom rack setup like on Alex's cargo bikes.  I hope it works out anyways.


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