Well that's why I designed my amp with an input buffer, you can increase the gain if need be. If you have to add a preamp then use a TDA 7630 or TDA1524 and build a dedicated preamp. I use the TDA 7630 in my Camm EquiTone preamp and it is the best preamp that I have heard. I am currently building a new preamp to test the TDA1524 chip.
Arty I stand corrected on the 8560, the 1562 is an class H amplifier.
DIY Preamplifier - The Book Worm
Mac
Sorry guys, the preamp ic is TA7630p, got too many tda's in my head
so.. say You drive 4 ohm speakers.
from a single 12v battery this chip will have something like 8v max output voltage.
we assume this swing.
so, 8/4 = 2A current.
this is stereo, so it will be closer to 4 A.
7/4 is 1,75 hours at full blast volume.
Does not sounds a lot.
but consider, that You will more than sure not run it at full blast.
I would estimate at least 3 hours of loud music.
//notice, one may argue that the amp has a certain % of efficiency, and a number of losses are to be included. But allso notice that speakers have impedance, my estimation is based on an ohmic load and constant current draw. //
from a single 12v battery this chip will have something like 8v max output voltage.
we assume this swing.
so, 8/4 = 2A current.
this is stereo, so it will be closer to 4 A.
7/4 is 1,75 hours at full blast volume.
Does not sounds a lot.
but consider, that You will more than sure not run it at full blast.
I would estimate at least 3 hours of loud music.
//notice, one may argue that the amp has a certain % of efficiency, and a number of losses are to be included. But allso notice that speakers have impedance, my estimation is based on an ohmic load and constant current draw. //
see datasheet.
test condition RL = 4 ohm
output power = 17w @10% THD.
P = U*I
P as power, U as voltage, and I as current.
I = U/R
where R is our load.
so P = Uˇ2/R
or sqrt(P*R) = U
witch is sqaure root of 68.
A tiny bit over 8 volts.
btw, it was only estimated.
Real life figures will differ.
It will be less output voltage since 10% THD sounds terrrible.
I would say that from a single 12v rated battery 8 volt output swing is on the edge.
Most likely You won't even utilise half of it.
It will be loud enough, given You use more or less efficient speakers.
test condition RL = 4 ohm
output power = 17w @10% THD.
P = U*I
P as power, U as voltage, and I as current.
I = U/R
where R is our load.
so P = Uˇ2/R
or sqrt(P*R) = U
witch is sqaure root of 68.
A tiny bit over 8 volts.
btw, it was only estimated.
Real life figures will differ.
It will be less output voltage since 10% THD sounds terrrible.
I would say that from a single 12v rated battery 8 volt output swing is on the edge.
Most likely You won't even utilise half of it.
It will be loud enough, given You use more or less efficient speakers.
The capacity is determined using a much lower current draw from the battery.
For example, a battery can actually provide 700mA for 10 hours. The capacity of that battery is 7Ah. If 7 amps are drawn, it can only provide that power for 38 minutes.
These numbers are hypothetical; I haven't referred to any battery datasheets. But they are somewhat realistic.
In fact, I believe the amp-hours standard is based on 20 hours of use. So a 7Ah capacity is determined by 350mA draw for 20 hours.
For example, a battery can actually provide 700mA for 10 hours. The capacity of that battery is 7Ah. If 7 amps are drawn, it can only provide that power for 38 minutes.
These numbers are hypothetical; I haven't referred to any battery datasheets. But they are somewhat realistic.
In fact, I believe the amp-hours standard is based on 20 hours of use. So a 7Ah capacity is determined by 350mA draw for 20 hours.
grab the cheapest possible battery charger You can get from Your favourite mega-junk store complex, roughly a nother 5-6 $.
A simple relay can put the battery on charger when the unit is off.
and ta-da, you got plenty of power for reasonably sensitive speakers, no problems with main's voltage junk, and possibly the cleanest DC powersupply one can have.
A simple relay can put the battery on charger when the unit is off.
and ta-da, you got plenty of power for reasonably sensitive speakers, no problems with main's voltage junk, and possibly the cleanest DC powersupply one can have.
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