I have a KAC-7251 kenwood. Below is the power specs. I want to run two comp
10" subs. The subs are 8 ohms each. It is a two channel amp and I want to
run both channels. Will using 8ohm subs cause any damage to the amp? Would I
be better off with 4ohm subs? I am new to this so, any thoughts would be
helpful.

Bridged Power Output at 14.4V (1kHz, 0.8% THD): 460 Watts x 1
- Maximum Output Power: 800 Watts
- Power Output at 2 Ohms, at 14.4V (1kHz, 0.8% THD): 230 Watts x 2
- Power Output at 4 Ohms, at 14.4V (20Hz-20kHz, 0.08% THD): 150 Watts x 2

In article 3kTzb.427668$Tr4.1207405@attbi_s03,
"Rich" wrote:

I have a KAC-7251 kenwood. Below is the power specs. I want to run two comp
10" subs. The subs are 8 ohms each. It is a two channel amp and I want to
run both channels. Will using 8ohm subs cause any damage to the amp? Would I
be better off with 4ohm subs? I am new to this so, any thoughts would be
helpful.

Bridged Power Output at 14.4V (1kHz, 0.8% THD): 460 Watts x 1
- Maximum Output Power: 800 Watts
- Power Output at 2 Ohms, at 14.4V (1kHz, 0.8% THD): 230 Watts x 2
- Power Output at 4 Ohms, at 14.4V (20Hz-20kHz, 0.08% THD): 150 Watts x 2



One of the suggested operating configurations is bridged mode with a 4
Ohm load for 460W RMS. Put the two 8 Ohm subs in parallel and you'll
have a 4 Ohm load. Each sub will get 230W RMS.

You could run the subs in stereo mode just fine. Each sub will get
about 75W RMS. The amplifier has a lot of current still available so
you can still add another pair of 4 Ohm speakers and another pair of 8
Ohm speakers to bring the impedance per channel down to 2 Ohms.

Amp's ratings from Crutchfield:
150 watts RMS x 2 at 4 ohms
230 watts RMS x 2 at 2 ohms
460 watts RMS x 1 bridged output at 4 ohms

To add Ohms in parallel, take the inverse of the sum of the inverses.

4 Ohms in parallel with 8 Ohms = 1/(1/4 + 1/8) = 2 2/3 Ohms

4 Ohms, 8 Ohms, and 8 Ohms = 1/(1/4 + 1/8 + 1/8) = 2 Ohms

On Thu, 04 Dec 2003 21:47:10 -0800, Kevin McMurtrie
wrote:

In article 3kTzb.427668$Tr4.1207405@attbi_s03,
"Rich" wrote:

I have a KAC-7251 kenwood. Below is the power specs. I want to run two comp
10" subs. The subs are 8 ohms each. It is a two channel amp and I want to
run both channels. Will using 8ohm subs cause any damage to the amp? Would I
be better off with 4ohm subs? I am new to this so, any thoughts would be
helpful.

Bridged Power Output at 14.4V (1kHz, 0.8% THD): 460 Watts x 1
- Maximum Output Power: 800 Watts
- Power Output at 2 Ohms, at 14.4V (1kHz, 0.8% THD): 230 Watts x 2
- Power Output at 4 Ohms, at 14.4V (20Hz-20kHz, 0.08% THD): 150 Watts x 2



One of the suggested operating configurations is bridged mode with a 4
Ohm load for 460W RMS. Put the two 8 Ohm subs in parallel and you'll
have a 4 Ohm load. Each sub will get 230W RMS.

You could run the subs in stereo mode just fine. Each sub will get
about 75W RMS. The amplifier has a lot of current still available so
you can still add another pair of 4 Ohm speakers and another pair of 8
Ohm speakers to bring the impedance per channel down to 2 Ohms.

Amp's ratings from Crutchfield:
150 watts RMS x 2 at 4 ohms
230 watts RMS x 2 at 2 ohms
460 watts RMS x 1 bridged output at 4 ohms

To add Ohms in parallel, take the inverse of the sum of the inverses.

4 Ohms in parallel with 8 Ohms = 1/(1/4 + 1/8) = 2 2/3 Ohms

4 Ohms, 8 Ohms, and 8 Ohms = 1/(1/4 + 1/8 + 1/8) = 2 Ohms

Good example of the math involved, but you would never parallel
speakers with different impedances together, because if you do, not
all of the speakers will receive the same amount of power.

Scott Gardner

In article ,
(Scott Gardner) wrote:

On Thu, 04 Dec 2003 21:47:10 -0800, Kevin McMurtrie
wrote:

In article 3kTzb.427668$Tr4.1207405@attbi_s03,
"Rich" wrote:

I have a KAC-7251 kenwood. Below is the power specs. I want to run two
comp
10" subs. The subs are 8 ohms each. It is a two channel amp and I want to
run both channels. Will using 8ohm subs cause any damage to the amp? Would
I
be better off with 4ohm subs? I am new to this so, any thoughts would be
helpful.

Bridged Power Output at 14.4V (1kHz, 0.8% THD): 460 Watts x 1
- Maximum Output Power: 800 Watts
- Power Output at 2 Ohms, at 14.4V (1kHz, 0.8% THD): 230 Watts x 2
- Power Output at 4 Ohms, at 14.4V (20Hz-20kHz, 0.08% THD): 150 Watts x 2



One of the suggested operating configurations is bridged mode with a 4
Ohm load for 460W RMS. Put the two 8 Ohm subs in parallel and you'll
have a 4 Ohm load. Each sub will get 230W RMS.

You could run the subs in stereo mode just fine. Each sub will get
about 75W RMS. The amplifier has a lot of current still available so
you can still add another pair of 4 Ohm speakers and another pair of 8
Ohm speakers to bring the impedance per channel down to 2 Ohms.

Amp's ratings from Crutchfield:
150 watts RMS x 2 at 4 ohms
230 watts RMS x 2 at 2 ohms
460 watts RMS x 1 bridged output at 4 ohms

To add Ohms in parallel, take the inverse of the sum of the inverses.

4 Ohms in parallel with 8 Ohms = 1/(1/4 + 1/8) = 2 2/3 Ohms

4 Ohms, 8 Ohms, and 8 Ohms = 1/(1/4 + 1/8 + 1/8) = 2 Ohms

Good example of the math involved, but you would never parallel
speakers with different impedances together, because if you do, not
all of the speakers will receive the same amount of power.

Scott Gardner


That's not something that needs to be avoided, but it is something to be
aware of when choosing speakers, amplifiers, and placement. I should
have mentioned it.

When in parallel, the power of each speaker consumed is inverse to its
impedance. An 8 Ohm speaker will consume half as much power of a 4 Ohm
speaker consumes. For 230W into 4 Ohms, 8 Ohms, and 8 Ohms parallel (2
Ohms total), you'd get 115W, 57.5W and 57.5W.

On Thu, 04 Dec 2003 23:59:11 -0800, Kevin McMurtrie
wrote:


To add Ohms in parallel, take the inverse of the sum of the inverses.

4 Ohms in parallel with 8 Ohms = 1/(1/4 + 1/8) = 2 2/3 Ohms

4 Ohms, 8 Ohms, and 8 Ohms = 1/(1/4 + 1/8 + 1/8) = 2 Ohms

Good example of the math involved, but you would never parallel
speakers with different impedances together, because if you do, not
all of the speakers will receive the same amount of power.

Scott Gardner


That's not something that needs to be avoided, but it is something to be
aware of when choosing speakers, amplifiers, and placement. I should
have mentioned it.


I would certainly try to avoid using mismatched subs in a
series, parallel, or series-parallel arrangement.
The only reason to use mismatched subs would be if you
happened to have several different subs lying around, and you had your
heart set on using all of them in an installation.
Mismatched subs introduce more problems than they're worth.
First, you have to have subs with power ratings such that the supplied
power can differ by a factor of two or more between the various subs
without overpowering or underpowering any of them. Then, you have to
consider whether your subs behave differently enough at different
power levels to affect the sound inside the car.
If you can think of a compelling reason to have multiple subs
being fed the same signal at different power levels, I'd like to know
it. I haven't heard of one yet.

Scott Gardner