Confusion about wiring subs to amp.

[jimbo_limited]

Amp is Pyle PLA-4280 4 channel 1400w Max


A buddy of mine purchased 2 rockford fosgate SVC 8 ohm subs Punch 2 (200w RMS). He didnt know they were the 8 ohm version. I sold him my old Pyle 1400w 4 ch amplifier. the main question is should he wire his subs bridged on the amp with a 8 ohm load or wire them parallel to a single bridge channel for 4 ohm load and use the other 2 channels to power his 6 1/2 spkrs.

The specs on the amp follows...

350W x 4 output
700W x 2 bridged output (350W x 2 + 700W x 1)

and i believe this is Max power output

[D.Kreft]

On Feb 13, 7:42 pm, jimbo_limited <jimbo_limited.
> wrote:
> Amp is Pyle PLA-4280 4 channel 1400w Max
>
> A buddy of mine purchased 2 rockford fosgate SVC 8 ohm subs Punch 2
> (200w RMS). He didnt know they were the 8 ohm version. I sold him my
> old Pyle 1400w 4 ch amplifier. the main question is should he wire his
> subs bridged on the amp with a 8 ohm load or wire them parallel to a
> single bridge channel for 4 ohm load and use the other 2 channels to
> power his 6 1/2 spkrs.

If he doesn't have an amp to run his mids and highs, then I would
recommend the latter configuration (subs in parallel on a bridged pair
of channels, mids & highs on the other two stereo channels).

-dan

[mfreak]

> 350W x 4 output
> 700W x 2 bridged output (350W x 2 + 700W x 1)
>
> and i believe this is Max power output

Max, bridged, and running at 22 volts I'm sure.... Anyway, "700"x2@4
ohms will be something like "350"x2@8. No matter how you set it up,
you'll only get "350" to each sub. So you might as well get those
"700" watts out of 2 channels instead of all 4. Then as D.Kreft
said, you could use the other 2 channels to send "700" watts to your
fronts or something.

[jimbo_limited]

So i would hook up his subs parallel and run them to a 4 ohm load for 350w RMS. Its shy 50w but its better than an 8 ohm load and losing over 100w to each.


Thnx

[D.Kreft]

On Feb 15, 1:35 pm, jimbo_limited <jimbo_limited.
> wrote:

> So i would hook up his subs parallel and run them to a 4 ohm load for
> 350w RMS. Its shy 50w but its better than an 8 ohm load and losing
> over 100w to each.

Well, that all depends upon your definition of "better."

If you're concerned at all about:

* amp overheating,
* wear and tear on the subwoofers
(being driven so close to their maximum rating doesn't make
'em last any longer),
* dynamic headroom, or
* damping factor
* keeping the subs "in balance" (output wise) with the mids +
highs

then "better" may very well be to use the subs as an 8-Ohm stereo pair
on two channels using the other two to run the mids and highs.

But if your only concern is making this thing as loud as possible,
then all this is moot--wire it up in any sane way that gets you the
most power from your amp.

-dan

[mfreak]

I think getting the most power out of an amp outweighs most of the
items you bring up below:

> * amp overheating,

Add a relay and some fans if it's an issue, it's a lot cheaper than
getting a 2nd amp

> * wear and tear on the subwoofers
> (being driven so close to their maximum rating doesn't make
> 'em last any longer),
> * keeping the subs "in balance" (output wise) with the mids +
> highs

Either way, you're sending appx. the same power to each sub, so I dont
understand what point youre trying to make? Speaking of balance, the
subs will be perfectly balanced to each other, you won't have to set 2
gains as the amp will only be pushing one channel.

> * dynamic headroom, or

I know what headroom is in a general sense, wouldn't you ideally want
to push an amp as hard as possible without clipping? Would an amp
clip easier aat the same RMS if it was bridged? Would your quiet
parts be disproportionally noisier?

> * damping factor

My understanding is you want the highest possible damping factor for
SQ reasons, correct? Does halving the amp's load's impedance cut the
damping factor in half? Or worse? I've always known that subs running
on bridged amps lose some SQ, but idk how much, it could be negligible
for all I know. I've ALWAYS run subs on bridged amps, in every single
system I've ever had, for purely economical reasons. I've always been
content with my sound, but who knows, but maybe idk what I'm missing.
My system isn't THAT great, but I've never heard any better one, I
just don't know anyone else into car audio...

[D.Kreft]

On Feb 16, 8:24 am, "mfreak" > wrote:

> > * amp overheating,
>
> Add a relay and some fans if it's an issue, it's a lot cheaper than
> getting a 2nd amp

Fans are not always possible, and in some cases, where they are
already installed, they may not be sufficient.

> > * wear and tear on the subwoofers
> > (being driven so close to their maximum rating doesn't make
> > 'em last any longer),
> > * keeping the subs "in balance" (output wise) with the mids +
> > highs
>
> Either way, you're sending appx. the same power to each sub, so I dont
> understand what point youre trying to make?

Given an amp that advertises 100W x 2 @ 4 Ohms, it's safe to assume
that you're going to get 50W x 2 @ 8 Ohms (unless you've got a fancy
amp that doesn't care what your speaker's impedance is and adjusts
output to produce the same amount of power no matter what you slap on
it).

Just to clarify, all of my recommendations have been assuming that two
channels would be used for the subs, and the other two for the mids &
highs. With that in mind, given this particular setup, you would
either get:

700W x 1 @ 4 Ohms (2 - 8 Ohm subs wired in parallel)

OR

175W x 2 @ 8 Ohms (2 - 8 Ohm subs, stereo)

Since the original poster never mentioned any other amps in the
system, I can only assume that this is the only sane recommendation to
make. If there *is* some mystery amp somewhere out there in the car,
then you could effectively turn this 4-channel amp into a 2-channel
amp:

700W x 2 @ 8 Ohms

In which case, yes, one would get just as much power per sub (350W) as
he would using my first recommendation, above.

> Speaking of balance, the
> subs will be perfectly balanced to each other, you won't have to set 2
> gains as the amp will only be pushing one channel.

By "balance" I was referring to the "tonal balance" as in having bass
that complements, not overpowers the rest of the system. Granted,
though, if this amp truly does create 350W x 4 @ 4 Ohms, then the
problem the owner is likely to face is not whether his bass overpowers
his mids and highs, but rather whether his mids and highs can take
this. Even with careful gain tweaking, the potential for destroying
the smaller, more delicate speakers is going to be high.

Of course, this amp *is* made by Pyle--so I'm not sure I'd trust those
specs any further than I could throw 'em. :-)

> > * dynamic headroom, or
>
> I know what headroom is in a general sense, wouldn't you ideally want
> to push an amp as hard as possible without clipping? Would an amp
> clip easier aat the same RMS if it was bridged? Would your quiet
> parts be disproportionally noisier?

Think about it for a second...if your "baseline" volume is higher, you
have less room for dynamic transients and are more likely to run into
amp clipping problems.

Imagine jumping on a trampoline inside a building with a 15' ceiling.
You're happily "tramping" along at a leisurely rate and your head gets
no closer than 6' of the ceiling--plenty of space. Suddenly, you get
the urge to "give it all ya got" and you jump as hard as you can. This
move brings you to within 3' of the ceiling.

Now, imagine that you come back several weeks later after working out
and maybe even taking anabolic steroids (or maybe someone put longer
legs on your trampoline--either approach works for this analogy). You
exert the same amount of effort in your leisurely rate, but now,
instead of having 6' of headroom, you now only have 3'--and you're not
even trying. Then, you get "that urge" again and jump as hard as you
can...what happens? Yeah, cracked cervical vertebrae and paralysis
from the neck down--you've been clipped.

See what I'm getting at now? If your normal listening is already
running near the limits of your equipment, you're not going to have as
much to give when you place a sudden demand on your system (like a
particularly dynamic piece of music).

Of course, my assumption here is that you've got speakers that can
handle whatever you throw at them. :-)

> > * damping factor
>
> My understanding is you want the highest possible damping factor for
> SQ reasons, correct?

Yes.

> Does halving the amp's load's impedance cut the
> damping factor in half? Or worse?

The damping factor is directly and linearly proportional to the
impedance of the load:

http://en.wikipedia.org/wiki/Damping_factor

> I've always known that subs running
> on bridged amps lose some SQ, but idk how much, it could be negligible
> for all I know.

Whether it is audible or not depends upon you and your equipment. In
the informal (read "non-scientific") tests that I've performed, I
actually tended to prefer an 8-Ohm bridged load over a 4-Ohm bridged
load on the same amp, using the same enclosure and speaker. Your
mileage, of course, may vary.

-dan