High efficiency sub amp needed!

[Eric Desrochers]

Hello! I'm looking for an high efficiency sub amp in the 500 watts
range, on a 4 ohms load. Low idle current would be nice too.

I was initially set on a JL Audio 500/1 until I come by a review that
revealed an abysmal efficiency of 57%.

I'm now looking at Kenwood KAC-9102D, Pioneer Premier PRS D2000T and
Alpine MRD-M605,

Since all those are fairly new models, reviews are scarce and I could
not find the efficiency number anywhere. Anyone got them numbers?

This is going in a small RV where battery operation at moderate volume
for long time is needed, hence the high efficiency requirement.

Comments and suggestions welcomed!

--
Eric (Dero) Desrochers
http://homepage.mac.com/dero72

Hiroshima 45, Tchernobyl 86, Windows 95

[[email protected]]

Eric Desrochers wrote:

> Hello! I'm looking for an high efficiency sub amp in the 500 watts
> range, on a 4 ohms load. Low idle current would be nice too.


Then you want to stay away from anything labeled "Class A", that's for
sure. Your best bet would be a Class B or, depending upon your
application and the amp itself, a Class D. Google is your friend if you
want to know why.

> I was initially set on a JL Audio 500/1 until I come by a review that
> revealed an abysmal efficiency of 57%.

That actually doesn't sound so bad to me. Fifty-seven percent is pretty
darn good.

> Since all those are fairly new models, reviews are scarce and I could
> not find the efficiency number anywhere. Anyone got them numbers?

I don't think you're going to find efficiency numbers. Traditional
amplifiers are typically <50% efficient. The only reason a company
would have to publish such an unusual spec is because the efficiency
their amp boasts is unusually high. If the amp you're looking at is one
of JL's Class D designs, then I would say that's definitely the case.

> This is going in a small RV where battery operation at moderate volume
> for long time is needed, hence the high efficiency requirement.

You've got an RV? Surely you have room for another battery? If you want
to play the system at "moderate volumes" (whatever that means) then
your best bet is to make sure that you have an ample supply of
electrons, preferably on an isolated electrical system (i.e. one
battery for the RV's electronics, one for the sound system with an
isolator between the two so they can both be charged by the same
alternator). That way, you can crank it up all you want until the thing
dies, then start your engine back up and recharge the sound system's
battery. :-) Keep in mind, though, that the more batteries you add, the
more of a load that'll present on your alternator!

Also, if you're trying to reproduce low-frequencies (i.e. you have
subwoofers in your Winnebago), then that's going to gobble up even more
power than if you have just a couple sets of 6x9's doing your
bidding--it takes a lot of juice to reproduce those sub-bass
frequencies.

All in all, I believe you'll be wasting your time trying to shop for
amps based upon efficiency numbers--percentage-wise, I just can't see
it making that big of a difference for you. Playing your system with
the engine off for 55 minutes versus 60 minutes before killing the
battery isn't really worth the potential sacrifice you'll be making in
the quality of the amplifier. Buy what sounds the best for the amount
of money you're willing to shell-out...shopping for anything else is
likely only going to leave you disappointed ("Wow Eric, you sure can
play your system a long time at moderate values with the engine shut
off...too bad it doesn't sound very good.")

Just my $0.02. Your mileage may vary.

-dan

[Kevin McMurtrie]

In article >,
(Eric Desrochers) wrote:

> Hello! I'm looking for an high efficiency sub amp in the 500 watts
> range, on a 4 ohms load. Low idle current would be nice too.
>
> I was initially set on a JL Audio 500/1 until I come by a review that
> revealed an abysmal efficiency of 57%.
>
> I'm now looking at Kenwood KAC-9102D, Pioneer Premier PRS D2000T and
> Alpine MRD-M605,
>
> Since all those are fairly new models, reviews are scarce and I could
> not find the efficiency number anywhere. Anyone got them numbers?
>
> This is going in a small RV where battery operation at moderate volume
> for long time is needed, hence the high efficiency requirement.
>
> Comments and suggestions welcomed!

Power is measured with a sine wave. A Class AB amp is less than 50%
efficient at making a full amplitude sine wave. Class H can be more
than 50% efficient under limited conditions. Class D has no limit to
efficiency but in practice they're given some analog qualities to make
them react more smoothly, like the proprietary Class T.

Don't forget about speaker efficiency. Car subs tend to have
ridiculously low efficiencies. Use a sub made for a large enclosure if
you can build such a setup in your car.

[Matt Ion]

wrote:
> Eric Desrochers wrote:
>
>
>>Hello! I'm looking for an high efficiency sub amp in the 500 watts
>>range, on a 4 ohms load. Low idle current would be nice too.
>
>
>
> Then you want to stay away from anything labeled "Class A", that's for
> sure. Your best bet would be a Class B or, depending upon your
> application and the amp itself, a Class D. Google is your friend if you
> want to know why.
>
>
>>I was initially set on a JL Audio 500/1 until I come by a review that
>>revealed an abysmal efficiency of 57%.
>
>
> That actually doesn't sound so bad to me. Fifty-seven percent is pretty
> darn good.
>
>
>>Since all those are fairly new models, reviews are scarce and I could
>>not find the efficiency number anywhere. Anyone got them numbers?
>
>
> I don't think you're going to find efficiency numbers. Traditional
> amplifiers are typically <50% efficient. The only reason a company
> would have to publish such an unusual spec is because the efficiency
> their amp boasts is unusually high. If the amp you're looking at is one
> of JL's Class D designs, then I would say that's definitely the case.
>
>
>>This is going in a small RV where battery operation at moderate volume
>>for long time is needed, hence the high efficiency requirement.
>
>
> You've got an RV? Surely you have room for another battery? If you want
> to play the system at "moderate volumes" (whatever that means) then
> your best bet is to make sure that you have an ample supply of
> electrons, preferably on an isolated electrical system (i.e. one
> battery for the RV's electronics, one for the sound system with an
> isolator between the two so they can both be charged by the same
> alternator). That way, you can crank it up all you want until the thing
> dies, then start your engine back up and recharge the sound system's
> battery. :-) Keep in mind, though, that the more batteries you add, the
> more of a load that'll present on your alternator!
>
> Also, if you're trying to reproduce low-frequencies (i.e. you have
> subwoofers in your Winnebago), then that's going to gobble up even more
> power than if you have just a couple sets of 6x9's doing your
> bidding--it takes a lot of juice to reproduce those sub-bass
> frequencies.
>
> All in all, I believe you'll be wasting your time trying to shop for
> amps based upon efficiency numbers--percentage-wise, I just can't see
> it making that big of a difference for you. Playing your system with
> the engine off for 55 minutes versus 60 minutes before killing the
> battery isn't really worth the potential sacrifice you'll be making in
> the quality of the amplifier. Buy what sounds the best for the amount
> of money you're willing to shell-out...shopping for anything else is
> likely only going to leave you disappointed ("Wow Eric, you sure can
> play your system a long time at moderate values with the engine shut
> off...too bad it doesn't sound very good.")
>
> Just my $0.02. Your mileage may vary.

Make that $0.04... I'll second everything Dan said :) Efficiency is a very rare
spec to find published for any amp, including professional sound-reinforcement
and "audiophile" home amps (at least until you start getting into the really
esoteric stuff, where "specs" make all the imagined difference, and the quality
of wires is judged by listed oxygen content).

[Eric Desrochers]

Hello!

> > I was initially set on a JL Audio 500/1 until I come by a review that
> > revealed an abysmal efficiency of 57%.
>
> That actually doesn't sound so bad to me. Fifty-seven percent is pretty
> darn good.

No. Try 91%, which is the case with the Eclipse XA2000! Further
searching revealed the Pioneer Premier PRS D2000T have 80%. xtant 1.1i
the same. This is no longer 1992 hehehe! :)

> > This is going in a small RV where battery operation at moderate volume
> > for long time is needed, hence the high efficiency requirement.
>
> You've got an RV? Surely you have room for another battery?

That's an old VW bus, not that roomy! I already have an Odyssey 100
amperes AGM auxiliary battery covering a fridge and interior lighting
and plan on adding another identical one as the starting/sound system
battery.

Another sound system (400 watts total) I had in another car lasted for
about 3 days with the kind of using I usually do, on an 55 amperes
Optima Yellow top. I'm now basically doubling the system's power AND
battery but it would have been great to increase autonomy on top of it.

Thanks!

--
Eric (Dero) Desrochers
http://homepage.mac.com/dero72

Hiroshima 45, Tchernobyl 86, Windows 95