Creating a bike trailer to play music

[Gabriel98]

Hi there,

I am trying to create a bike trailer with speakers so that I can play music and cycle at a protest event (critical mass). I already have a trailer (see below).

https://www.ebay.co.uk/itm/Folding-Bicycle-Cargo-Storage-Bike-Trailer-Enclosed-Cart-Removable-Cover-Hitch/352255353353?var=&hash=item52040e2209

I am now looking to get batteries and some speakers. I want to make the system as loud as possible with plenty of bass but I also want to keep it cheap and spend ideally under £400 on batteries and speakers ( I'm willing to buy secondhand stuff off gumtree, ebay etc.)

As I am no electrician, I thought I would ask around on this forum to see if anyone has some recommendations for batteries/speakers/general setup. 

However I am currently considering buying a leisure battery of around 100AH and a Mackie Thump 15A speaker (1300W). I am guessing I would also need an inverter to transfer from 12v DC to 230v AC from the battery to the speakers. I could maybe start off with one speaker and see if that is enough and then buy another if not.

The speaker will need power for roughly 3 hours and will be used roughly once a month so will need to be recharged once a month.

Many thanks for your help

 

[Richard-the-Ninth]

Not sure about the bass aspect, but did you know you can get 12v systems?

 

[Geoff1946]

Yes, I wouldn't go for an invertor. It's just inefficient to convert voltage up for a 230 volt amplifier which internally just converts it down again.

First, have a look what mobile low voltage public address (PA), amplifiers you can get.  You may find a 24 volt unit is more readily available and suitable, in which case you would want two leisure batteries to wire in series. That will still be cheaper than a decent invertor.

 

[phil d]

CPC farnell do some 'mobile' pa systems, failing that have a word with a car radio shop, or even better, find one of those annoying young chavs in your area, they have massive sound systems in their cars.

 

[Gabriel98]

Does it make a difference that the Mackie speaker is active and therefore does not need an amplifier? 

 

[phil d]

Does it make a difference that the Mackie speaker is active and therefore does not need an amplifier? 

Do you have the Mackie speaker already? If not then I'd use something else. I know of a place near me who'd be happy to advise you on how to do it, no need for inverters, all 12v, they do some really loud kit and have been in several big competitions

K & M Acoustics

Car Audio & Entertainment Systems

0 reviews on Yahoo

Seven Stars Road, Wigan, WN3 5AT

(01942) 820174

Give them a ring, they'll sort you out, they're very well known in the car audio world.

 

[apprentice87]

Your sums do not add up.. You say the speaker draws 1300W.. Ok, that is, at 12v, 108A Your battery will not supply that.... A 100ah battery WILL NOT supply 100a for an hour. It may well supply 5A for 20 hours, but no way will it supply 100A for a hour. You are on about three hours though.. Just buy a generator and be done with it...

john..

 

[ProDave]

Your sums do not add up.. You say the speaker draws 1300W.. Ok, that is, at 12v, 108A Your battery will not supply that.... A 100ah battery WILL NOT supply 100a for an hour. It may well supply 5A for 20 hours, but no way will it supply 100A for a hour. You are on about three hours though.. Just buy a generator and be done with it...

john..

You have to get used to "Hi Fi Speak"

A "1300W" amplifier in "hi Fi speak" probably equates to 130W of  real rms power consumption.

 

[apprentice87]

Ahhhh, i see..

john....

 

[Geoff1946]

Yes, the power ratings quoted relating to amplifiers and speakers can be most misleading. "Music power" and "Peak (music) power", bear little relation to actual power that can be related back to the actual electrical power supplied into a system.  IMHO these figures are quoted in advertising mainly to mislead, or at best to baffle non-technical buyers. The true measure of an amplifier's capability would be RMS output power, which is rarely quoted.

To come back to the original question however I still maintain that using an invertor to power an amplifier intended for mains use is NOT the best way to go.

It will work, but you will be wasting perhaps half of your battery capacity (and hence running time), in the power conversion processes.

I think the recommendation to go for car audio gear will best serve your purpose. You could perhaps even source your gear from a car breaker's yard  but you will need someone with the technical knowhow to help wire it up for you.

 

[Tony S]

It comes down to speaker efficiency, my four Jamo 266’s are rated at 266W RMS their output music power is well over 1000W each. In my lounge the four channels tick over at about 2 to 4 W to give quite a loud music output, for classical music it will be <2W.