Hey all, as the title suggests im currently in the planning phase of trying to build my own portable bluetooth speaker..
my question is, should i pick 4 Ohm speakers or 8...?
The AMP im planning on using is 2.1ch 2x50W+100W, rated for 12-24v operation.
I dont really want to have to build my own battery packs and Im Having a hard time finding a 24v rechargable battery pack.. so planning on using a 12-24v step up transformer aswell just so i can squeez more W out of my amp... (because im guessing the listed Wattage on the amp is at max operating voltage..?)
Im fairly new the while dyi audio scene so any tips regarding anything really is appreciated..!😀
my question is, should i pick 4 Ohm speakers or 8...?
The AMP im planning on using is 2.1ch 2x50W+100W, rated for 12-24v operation.
I dont really want to have to build my own battery packs and Im Having a hard time finding a 24v rechargable battery pack.. so planning on using a 12-24v step up transformer aswell just so i can squeez more W out of my amp... (because im guessing the listed Wattage on the amp is at max operating voltage..?)
Im fairly new the while dyi audio scene so any tips regarding anything really is appreciated..!😀
#1, I'd say, dont use the step up device - unless you really know what you're doing. Can cause more trouble than it's worth...
#2, settle on +18V, because two lead-acid (cheap) 12V batteries, when charged, can go over the max rating of many "24V" class d chips. Finding an 18V charger then becomes the problem... Individually charging 3, 6V batteries also would stink...
You could do 5, 18650 lithium cells and stay below the 24-25V hard max input of many of these amps. Then the problem is "5", as many chargers for these batteries take 4 at a time.
#3, I'd say with the 18V supply, choose the 4 Ohm speakers. Pay attention to the efficiency of the speakers you choose, as in the higher the better and try to match as best you can the efficiency values between the woofer and other drivers - along with everything else needed to make a decent speaker system.
Try not to expect too much; yeah it sez "2x50W+100W" but at the max possible output, class d audio distortion goes up quickly. The amp may actually run much more comfortably at 2x25W+50W... With higher efficiency speakers, this can still be pretty good in terms of how loud you'll be able to play it. Good luck with your new system.
#2, settle on +18V, because two lead-acid (cheap) 12V batteries, when charged, can go over the max rating of many "24V" class d chips. Finding an 18V charger then becomes the problem... Individually charging 3, 6V batteries also would stink...
You could do 5, 18650 lithium cells and stay below the 24-25V hard max input of many of these amps. Then the problem is "5", as many chargers for these batteries take 4 at a time.
#3, I'd say with the 18V supply, choose the 4 Ohm speakers. Pay attention to the efficiency of the speakers you choose, as in the higher the better and try to match as best you can the efficiency values between the woofer and other drivers - along with everything else needed to make a decent speaker system.
Try not to expect too much; yeah it sez "2x50W+100W" but at the max possible output, class d audio distortion goes up quickly. The amp may actually run much more comfortably at 2x25W+50W... With higher efficiency speakers, this can still be pretty good in terms of how loud you'll be able to play it. Good luck with your new system.
Hey, thanks for your inputs 😀
Some follow up questions though..
#1 - in what way could a step up cause more damage then good..?
#2 - when you say i should pick speakers with high efficiancy are you speaking of the dB level..?
When it comes to the amp and the output power im not expecting any extrordanary sound quality aslong as it plays decently loud..
Maybe look around and read some of the Many threads here from All the others that have asked very similar questions about 'boom boxes' etc.
Well if you share the datasheet for the amp, we can check if its good into 4 ohms, that
100W power rating sounds pretty mythological for 24V unless its into 2 ohms.
EMI due to switching probably.
Not the max power, the efficiency. Its usually given as a sensitivity ( dB for 1 watt input at 1 metre distance at 1kHz ), but its really a convoluted way to give the power efficiency of the transducer. A 100% efficient speaker is about 112dB at 1m and 1W. Speakers are not very efficient and range from 85dB to about 100dB sensitivity in practice. Speakers at the higher end of this range will need a lot less power for the same loudness - so much longer battery life. However they tend not to have bass extension (low frequency range) without a large box.
For a portable speaker there's a trade off between size, battery life and bass response - often a ported design is used to help with this.