This may be up Dave Plowman's street...
If I buy a cheapo 4 x 7 watts car stereo, and plan to use only two speakers, do I benefit power-wise by ganging 2 outputs together per side? Obviously with the F / R balance set at midway. In other words do I then get 2 x 14 watts?
It's so cheap that the 7w output is probably PMPO too!
Cheers, Ken.
Along with apparently every builder's truck in London this morning? When I'd like to get the car washed. ;-)
I'm afraid this won't work - and don't try it as you'll probably blow things up. You can 'bridge' amplifiers to increase the power, but it's not as simple as just paralleling the outputs - you'd need to alter the inputs to them as well as correct connection of the outputs. Easier to just use an add on unit, unless you like modifying things. ;-)
Yup. About 4 watts is more like it in conventional measuring terms.
Cheers Dave,
Well I don't mind modding things, but since this'd be a new unit (I'd bugger the warranty) *and* the circuit board will be a mess of no name LSI bricks
*and* I've only ever soldered audio connections, I'd probably best leave well alone!Regs Ken.
You can buy a cheapo amp for next to nothing, although several years ago when I went round all the shops buying things and bringing them back (they love me) I found you could get something LOUD for £40 but it made your ears bleed not in a good way. I ended up with a discontinued Tandy amp from their seconds & returns superstore (sadly defunct now) for £35 but even at the original £70 it was a fantastic bargain. Very big, with two big fuses and a claimed 75W or so; I reckon half that in reality, pretty good.
To be fair, if they quote 7wpc it probably really is 7wpc. If they were lying they would make the effort to lie properly I'm sure. And 7wpc is pretty good for a car stereo.
They're probably quoting some form of 'music power'. Unless you use a bridge output stage or a transformer, or lower than normal impedance speakers, the most you can get out of a 14 volt HT rail into 4 ohms is just over 4 watts, quoted in the same way as is common for 'proper' amplifiers.
Although bridged outputs are the norm in car stereos
Yes - but a single bridge design gives 6 watts into 4 ohms from 14.4V. It depends on how you specify the measurement - and car ICE makers tend to be somewhat generous with this.
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