help with three subs

[xman]

So I got a custom box(for free) that fits 3 10" subs. The subs are
going to be the sony xplod 10's, and I was wondering if there is a way
to wire them so that I have stereo from two subs, and mono from the
middle? Is it possible to do it all with only one amp? Thanks.

[MOSFET]

> So I got a custom box(for free) that fits 3 10" subs. The subs are
> going to be the sony xplod 10's, and I was wondering if there is a way
> to wire them so that I have stereo from two subs, and mono from the
> middle? Is it possible to do it all with only one amp? Thanks.
>

Your question is a little confusing. I'm not sure what you're asking here.

Typically your subs are ALL wired in mono. You gain basically nothing by
trying to hook up subs in stereo.

I would DEFINITELY suggest all three of your subs be wired in mono (combine
your left and right channels into one channel and have that go to your sub).
Then use your single amp to drive all three subs.

Make sure that the load all three subs present to the amp does not exceed
the amp's bridged mono capability. In other words, if you have three 4 ohm
subs and you wire them all in parallel, this will present a 1.3 ohm load.
Make sure your amp is capable of driving such a load. I don't know exactly
WHAT subs you have or the amp you have to drive them so I can't specifically
speak to this. If you give us that information, we can better help
recommend a configuration that maximizes the amp and subs.

MOSFET

[Matt Ion]

MOSFET wrote:
>>So I got a custom box(for free) that fits 3 10" subs. The subs are
>>going to be the sony xplod 10's, and I was wondering if there is a way
>>to wire them so that I have stereo from two subs, and mono from the
>>middle? Is it possible to do it all with only one amp? Thanks.
>>
>
>
> Your question is a little confusing. I'm not sure what you're asking here.
>
> Typically your subs are ALL wired in mono. You gain basically nothing by
> trying to hook up subs in stereo.
>
> I would DEFINITELY suggest all three of your subs be wired in mono (combine
> your left and right channels into one channel and have that go to your sub).
> Then use your single amp to drive all three subs.
>
> Make sure that the load all three subs present to the amp does not exceed
> the amp's bridged mono capability. In other words, if you have three 4 ohm
> subs and you wire them all in parallel, this will present a 1.3 ohm load.
> Make sure your amp is capable of driving such a load. I don't know exactly
> WHAT subs you have or the amp you have to drive them so I can't specifically
> speak to this. If you give us that information, we can better help
> recommend a configuration that maximizes the amp and subs.
>
> MOSFET

"The subs are going to be the sony xplod 10's..."

[xman]

Ok, thanks, I didn't know if wiring subs in stereo would sound better
than mono, because I've had two different systems in my car before, and
I wired one in stereo, and it sounded awesome. The amp I'm getting will
definitely be 1 ohm stable, too. Probably the kenwood excelon x812d.

[Captain Howdy]

I'm sure that you'll get awesome stereo sound out of your subs with the
kenwood excelon x812d mono block amplifier. Really, I think that you will. LOL



In article m>, "xman"
> wrote:
>Ok, thanks, I didn't know if wiring subs in stereo would sound better
>than mono, because I've had two different systems in my car before, and
>I wired one in stereo, and it sounded awesome. The amp I'm getting will
>definitely be 1 ohm stable, too. Probably the kenwood excelon x812d.
>

[KOA]

wire mono( parallel). that amp can take it no problem


--
KOA

[e-nigma]

"KOA" > wrote in message
...
>
> wire mono( parallel). that amp can take it no problem
>
>
> --
> KOA

Captain's point was that amp is mono so you can not even hook it up stereo
if if you wanted to....

[MOSFET]

"e-nigma" > wrote in message
...
>
> "KOA" > wrote in message
> ...
> >
> > wire mono( parallel). that amp can take it no problem
> >
> >
> > --
> > KOA
>
> Captain's point was that amp is mono so you can not even hook it up stereo
> if if you wanted to....
>
Yes, but if that Kenowood mono amp is one ohm stable, you should be able to
connect all three Sony subs in parallel no problem. It should work GREAT
for you!

MOSFET

[Captain Howdy]

Never mind should. It will work great until that poor kenwood melts.



In article >, "MOSFET"
> wrote:
>
>"e-nigma" > wrote in message
...
>>
>> "KOA" > wrote in message
>> ...
>> >
>> > wire mono( parallel). that amp can take it no problem
>> >
>> >
>> > --
>> > KOA
>>
>> Captain's point was that amp is mono so you can not even hook it up stereo
>> if if you wanted to....
>>
>Yes, but if that Kenowood mono amp is one ohm stable, you should be able to
>connect all three Sony subs in parallel no problem. It should work GREAT
>for you!
>
>MOSFET
>
>

[xman]

what about running them with the kenwood 7252(that's what I meant for
stereo), my choice for mono parallel was the excelon. Also, does anyone
know if the kenwood 9152 would work for mono-parallel wiring in my
schematic; is it 1 ohm stable?

[D.Kreft]

xman wrote:
> what about running them with the kenwood 7252(that's what I meant for
> stereo), my choice for mono parallel was the excelon. Also, does anyone
> know if the kenwood 9152 would work for mono-parallel wiring in my
> schematic; is it 1 ohm stable?

Wiring subwoofers in stereo is not going to provide you with any sonic
benefits because the human ear cannot localize sub-bass
frequencies--especially not in a highly reflective environment such as
an automobile interior. How the human brain localizes sound is rather
complex, but basically the brain has a very tough time localizing
frequencies whose wavelength is greater than the width of your head
(see http://www.ausim3d.com/about/AuWeb_perception.html). This is why
you can put a subwoofer in your center console, in the trunk of your
car, or even underneath your dashboard and get roughly the same results
in either case, something you most definitely cannot do with a tweeter
or a midrange speaker--which are *very* finicky w.r.t. placement.

There's another good reason not to do this "stereo-mono" thing. If your
box is one big chamber, you're going to open yourself up to modulation
distortion--where differences in the signal in one speaker has an
adverse affect on the others. The result may be "inaudible" but yet
still noticeable; meaning that you may not be able to put your finger
on it but you'll notice that something isn't quite right--the bass
response may very well be muddy. Even if your box is constructed of
three individually-sealed chambers (which it really should be), you're
still going to have an uneven amount of power going to all your
speakers....one sub may have 2x the power of the other two. All this is
going to do is wear-out one of your subs twice as fast as the others
and again probably muddy-up your sub-bass response.

So any way you slice it, this really doesn't make any practical sense.
Wire 'em all up in mono is such a way as to make your amplifier happy,
and in such a way as to deliver the *same* amount of power to each
speaker (i.e. don't wire two in parallel and one in series with the
parallel pair or something goofy like that). The idea here is to get
all your subs doing the same thing at the same time and all at the same
intensity. Anything other than that is going to result in a system
that's destined to fail to live up to its potential.

Lastly, you mention you bought a custom box but I didn't catch whether
or not you had it custom-built for the speakers you have. If you
didn't, then it's not really a custom box...at least not for your subs.
All boxes are not the same, and not all subwoofers require the same
volume (or even type) of enclosure to achieve optimum performance. If
you have not done so already, please check with the manufacturer or a
dealer of your subwoofers and have them look things over--taking this
extra step may very well save you frustration over a
less-than-satisfying-sounding system and even may save you money;
improperly-sized enclosures can drastically reduce the life expectancy
of any speaker.

Check out the tutorials entitled "Designing Subwoofer Enclosures" and
"The Myth of the Magic Box" on the JL Audio website
(http://mobile.jlaudio.com/support_pages.php?page_id=141) for more
detail on the points I've brought up here.

-dan

[xman]

Thanks a lot for all the help guys. The verdict is I'm going with the
Kenwood excelon x812d wired in parallel-mono, and probably some added
fans or a custom box for the amp with dual fans to keep an air path,
since I'm sure that 919 watts will generate A LOT of heat. I'm also
getting a 3 farad power acoustik capacitor; and I work on cars a lot,
so should I just charge that with my battery charger before I stick it
in my car?

[Captain Howdy]

I hate to say this, but you'll never see 919 watts out of that amp, not even
on a good day.


In article . com>, "xman"
> wrote:
>Thanks a lot for all the help guys. The verdict is I'm going with the
>Kenwood excelon x812d wired in parallel-mono, and probably some added
>fans or a custom box for the amp with dual fans to keep an air path,
>since I'm sure that 919 watts will generate A LOT of heat. I'm also
>getting a 3 farad power acoustik capacitor; and I work on cars a lot,
>so should I just charge that with my battery charger before I stick it
>in my car?
>

[MOSFET]

> I hate to say this, but you'll never see 919 watts out of that amp, not
even
> on a good day.
>
Unless you've ALSO installed a 200 ampere HO alternator, I'm afraid Howdy is
EXACTLY right. You will NEVER see 919 watts, no matter how many farads of
capacitance you add.

MOSFET

[xman]

well about how many can I expect with my current alternator? It's a 96
trans am with a 140 amp alt.

[Captain Howdy]

You'll get about 500-550 watts, How clean it's going to be in that area is
hard to say. This amplifier has 2x30amp fuses. The power ratings on this amp
are shady at best (see online manual), all of Kenwoods power ratings on this
amplifier are at 100hz when you set the cross-over at 60 - 80hz as most people
do, you'll see the power ratings drop big time.


140amp alternator is more then enough for it.

In article . com>, "xman"
> wrote:
>well about how many can I expect with my current alternator? It's a 96
>trans am with a 140 amp alt.
>

[D.Kreft]

xman wrote:

> I'm also
> getting a 3 farad power acoustik capacitor; and I work on cars a lot,
> so should I just charge that with my battery charger before I stick it
> in my car?

Your capacitor should come with a small resistor on the order of
something like 1kOhm. Whatever 12V source you use, make sure you charge
that thing with the resistor in series with your power supply (be sure
to hold it with a pair of pliers--it'll likely get kinda hot). A
discharged capacitor looks like a dead short to DC until it starts
charging up, and if you just slap 12V on it immediately, you're likely
going to pop a fuse/breaker and/or create a nasty scar wherever the
circuit is closed (from the arcing).

Remember, three Farads is a LOT of capacitance--treat that thing like
it's filled with lightning and don't try to charge it until *after*
you've securely mounted it in your vehicle (and have a means to protect
the terminals). And remember...NEVER EVER EVER lick a capacitor's
terminals like you would a 9V battery...ever. Seriously. Don't.

-dan

[GregS]

In article om>, "D.Kreft" > wrote:
>xman wrote:
>
>> I'm also
>> getting a 3 farad power acoustik capacitor; and I work on cars a lot,
>> so should I just charge that with my battery charger before I stick it
>> in my car?
>
>Your capacitor should come with a small resistor on the order of
>something like 1kOhm. Whatever 12V source you use, make sure you charge
>that thing with the resistor in series with your power supply (be sure
>to hold it with a pair of pliers--it'll likely get kinda hot). A
>discharged capacitor looks like a dead short to DC until it starts
>charging up, and if you just slap 12V on it immediately, you're likely
>going to pop a fuse/breaker and/or create a nasty scar wherever the
>circuit is closed (from the arcing).
>
>Remember, three Farads is a LOT of capacitance--treat that thing like
>it's filled with lightning and don't try to charge it until *after*
>you've securely mounted it in your vehicle (and have a means to protect
>the terminals). And remember...NEVER EVER EVER lick a capacitor's
>terminals like you would a 9V battery...ever. Seriously. Don't.

I'm running the calculator and the first formula I come across is time
in secs. times farads = 1K times 3 Farad = 3000 secs. I think I would use no more than 100
ohms and about a 2 watt resistor. A 12 volt lamp is also good to use.

greg

[KU40]

you'll just be wasting your money on that cap. You have plenty of
alternator power to keep up with that amp.


--
KU40

[D.Kreft]

KU40 wrote:

> you'll just be wasting your money on that cap. You have plenty of
> alternator power to keep up with that amp.

Well, that kinda depends upon how you define "keep up with", I think.

If you're talking about consistent, relatively steady current draws of
up to 140A, then yeah, that alternator will "keep up". But music is not
typically sinusoidal--it's dynamic.

What the alternator is not likely to keep up with are large transient
spikes (especially those occurring in rapid succession) in current
demand that cause supply voltage fluctuations. After all--automobile
alternators were not designed for highly dynamic loads--they were
designed to provide power to relatively static loads like lights and
your A/C...the dynamic loads they *do* serve (intermittent wipers, turn
signals, horns, etc.) are peanuts compared to the demands of a
high-powered audio amplifier. It's a whole 'nother world.

These fluctuations will mean degraded transient response ("attack") to
one degree or another. Whether these fluctuations will produce
*audible* differences in the system being discussed is, well, quite
dependent upon just how keen the listener's ears are. But I'm pretty
sure the amp will notice a difference and may thank you for it by
running a bit cooler, particularly if the amp has a regulated power
supply (which draws more current to compensate for voltage sags). Every
amplifier has some degree of input volatage capacitance, but nothing
like a big ol' quart-sized can of "dielectric sandwich".

To the original poster: if you haven't purchased the capacitor already,
my suggestion would be to install your system without it and see if
your dealer would be amenable to giving you a "test drive" in your
vehicle in the parking lot to see if the thing is going to be worth
your while. If you've already purchased it, well, then go ahead and
install it...unless you do the "test drive" on your own and determine
that it doesn't make any difference in your system. If you're nice (and
haven't boffed the capacitor), maybe they'll let you return it.

-dan

[keith]

D.Kreft wrote:

> Remember, three Farads is a LOT of capacitance--treat that thing like
> it's filled with lightning and don't try to charge it until *after*
> you've securely mounted it in your vehicle (and have a means to protect
> the terminals). And remember...NEVER EVER EVER lick a capacitor's
> terminals like you would a 9V battery...ever. Seriously. Don't.
>
> -dan
>

LOL!! Seriously, welcome back dKil.

Nice posts.

KeithS

[KU40]

a couple weeks ago when my big amp went down i only had my two smaller
ones going, and they pull probably about 50 amps at full tilt. I only
have a 105 amp alternator and my voltage never dipped below normal.
his amp will only pull 10 more, and he has 35 more amps from the alt.
I'm fully confident he'll have no problems unless either the alt or
battery are already weak.


--
KU40

[D.Kreft]

KU40 wrote:

> a couple weeks ago when my big amp went down i only had my two smaller
> ones going, and they pull probably about 50 amps at full tilt. I only
> have a 105 amp alternator and my voltage never dipped below normal.

Did you have your headlights and A/C on? Auto manufacturers typically
only outfit their vehicles with enough alternator to run the car
itself, nothing else, so when you're driving around on a hot, humid
night with your high-beams and A/C on, listening to Depeche Mode at
full volume (as I was prone to do in my younger days), things can get
kinda rough, electrically speaking.

> his amp will only pull 10 more, and he has 35 more amps from the alt.
> I'm fully confident he'll have no problems unless either the alt or
> battery are already weak.

This very well may be true, which is why I was careful to note that it
would be a good idea to test the system with and without the cap.
before making a "from-the-hip" decision either way.

-dan

[xman]

Well, my battery is brand spankin new, one of those gold-level
batteries. My alt, doesn't really matter, because I have an extended
warranty on my car, so if it dies, I just get a new one for free! The
only reason I was thinking about getting a cap is because I always
heard that if you have a high end system, you should run 1 farad of
capacitance per 1k watts, and I also forgot to mention that I was also
looking at some boss audio amp that put out 1200 watts RMS(3000 max),
and that's why I was looking at a 3 farad cap.

[KU40]

D.Kreft Wrote:
>
> This very well may be true, which is why I was careful to note that it
> would be a good idea to test the system with and without the cap.
> before making a "from-the-hip" decision either way.
>
> -dan
I agree. I say to always try before making adjustments.

and xman, if you're looking for a true 1200 watts, don't get that Boss.
It'll give you 600. If you want over a kilowatt, provide us with a
budget and we'll point you to some good equipment.


--
KU40

[KU40]

D.Kreft Wrote:
>
> Did you have your headlights and A/C on? Auto manufacturers typically
> only outfit their vehicles with enough alternator to run the car
> itself, nothing else, so when you're driving around on a hot, humid
> night with your high-beams and A/C on, listening to Depeche Mode at
> full volume (as I was prone to do in my younger days), things can get
> kinda rough, electrically speaking.
> -dan

I know my A/C pulls a ton of current. It drops my voltage down about a
volt by itself, with nothing else running. That's about equal to a
large, full volume bass hit with my 1000 watt sub amp (and other two
amps running full tilt as well). So one could say that the A/C affects
the electrical system as much as my stereo does. Add them together and
it would be bad when running around town, stopping at lights and
whatnot. If I keep the speed (and subsequently RPM's) up, I'll usually
sustain about 1 volt down from normal with both running full tilt. but
it's ok for me, because I'm more of a windows-rolled-down kind of guy
except on long highway trips, and I'm not going to listen to my stereo
at even 1/4 volume the whole way.

so I can see your point. However I still think he'll be fine with his
140 amp alt. and 60 amp-pulling amplifier and A/C. With the topic of
transients and dynamic range in music that you were talking about
earlier, I think it helps my case as well. I read an article a few
months ago (afraid I can't find the link) that did a test on these
transients and the normal power being supplied by the amplifier, and
IIRC it found that on average, even at full tilt, an amp is only
supplying something like 10% of it's rated power. It only has small
instances where the actual output goes up to RMS rating or beyond.
However I would imagine this varies quite a bit with the music being
played especially when comparing bass lines, which in many systems have
the largest amplifiers. For example rock, with it's quicker kick drum
hits, has just those small spikes in output followed by pretty much
nothing until the next hit. Some rap, meanwhile, has extended bass
drops that require an amp to put out more power for longer periods.
Athough it still may be fairly low given impedence rises in sub
systems, some go over 20 ohms at certain frequencies (my sub actually
spikes over 40 ohms at 52 hz! that's a whopping 25 watts from my 1000
watt amp).

so anyways, that was a long-winded pile of tangents. I think the moral
is.......put it in your car and we'll see from there. ha


--
KU40

[MOSFET]

And remember...NEVER EVER EVER lick a capacitor's
> terminals like you would a 9V battery...ever. Seriously. Don't.
>
> -dan
>
LOL
That was great!

[MOSFET]

And remember...NEVER EVER EVER lick a capacitor's
> terminals like you would a 9V battery...ever. Seriously. Don't.
>
> -dan
>

Actually, a long, long time ago when I was young and stupid (well, OK, just
young), I was working on a friend's car and I needed to cut the positive
wire that ran from a .5 farad cap (the rest of the system was disconnected
from the battery) but the cap was fully charged. I used a thin bladed razor
knife to cut the wire and SOMEHOW while I was cutting the wire it must have
made contact with the car's chassis.

It wasn't so much as a spark, but an explosion. It VAPORIZED a whole
section of the razor knife I was using (a square inch chunk just
disappeared).

I'm trying to imagine what that would do to your tongue....

MOSFET

[GregS]

In article >, "MOSFET" > wrote:
> And remember...NEVER EVER EVER lick a capacitor's
>> terminals like you would a 9V battery...ever. Seriously. Don't.
>>
>> -dan
>>
>
>Actually, a long, long time ago when I was young and stupid (well, OK, just
>young), I was working on a friend's car and I needed to cut the positive
>wire that ran from a .5 farad cap (the rest of the system was disconnected
>from the battery) but the cap was fully charged. I used a thin bladed razor
>knife to cut the wire and SOMEHOW while I was cutting the wire it must have
>made contact with the car's chassis.
>
>It wasn't so much as a spark, but an explosion. It VAPORIZED a whole
>section of the razor knife I was using (a square inch chunk just
>disappeared).
>
>I'm trying to imagine what that would do to your tongue....


I was wondering if anybody had done that, like sticking a screwdriver
across the cap. Of course I have stuck a screwdriver across a battery.
The battery which was a large one inside an Army van which
I opperated and charged batteries to run remote radio planes. Well,
the battery caps were off. I heard a rushing sound and leaped out
of the van. Looking back saw gushers of battery acid hitting the ceiling
of the van. Man, I used to get all kinds of holes in my clothes
from those batteries.

greg

[xman]

I would just like to thank everyone for all the help; I ended up
getting the two sony P5 12's with a kenwood 9152D Amp, and I got the
cap because at least, it couldn't hurt anything, and since I could get
it for a good deal. This new system POUNDS. Thanks everyone for
everything.

xman