amplifier direction question

[ValveCoverGasket]

thanks! thats a really good explanation

i also see a lot of archived posts of folks recommending the NVX amps from a few years ago (likely the vintage pmk has on his boat) it seems like the latest NVX marine stuff is different than that era? are those still a viable choice?


alright, i promise ill stop side tracking now

[MLA]

is it worthwhile at all to consider the A/B kicker amps?
it seems like the "X" models are the newer D, but crutchfield and other places still seem to have the (i assume older design?) KMA series, or is that too outdated at this point to be worthwhile?

awesome info in this thread - lurking as i have a stereo redo on my list for this winter

The Kicker KMA and KXMA are actually 2 different series rather then an old and new. For the most part, the KXMA counter part offer a higher wattage to the KMA. Take the KXMA 2 chnl v's the KMA 2 chnl for example. The KXMA is also built with better features not offered on the KMA, which puts them in a higher price point. Clip detect, gasketed controls cover.

When I can, I do prefer the class-d over A/B. But I also base the decision on what im going to power and what our goals are.

In the case of this thread, it would take two KMA6004 to equal the wattage of a single KXMA12002. So thats the space for two amp, then splitting the RCA and double the power cables. Also means you would need 4 pair of speaker wires up the tower, one to each pod. With a 2 chnl amp, you can do it with only 2 pair of speaker wires.

Full disclosure, ive got a KMA3604 thats going to power a pair of KM* tower pods bridged for 180W rms each and a KMA 8001 for a pair of 2 ohm KM10 woofers. This fit the goals, space and budget.

[MLA]

ok, I think I understand that with the 8 channel ... now same question on the NVX 2 channel, as it seems to get the 4 ohm the watts per channel is 300 and per speaker is 150 ... right?

NVX VAD8402 – 2 channel 840 watts RMS (what I currently have driving the 4x Rev8s)
Splitting the two channels to the 4 speakers, one channel drives a pair.
2 ohm gives 420 watts per channel (2x) or 210 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

With a pair of 4 speakers wired to a single chnl, you can only have 2 ohm or 8 ohm. No way to get a 4 ohm loaf with a pair. A single speaker p/chnl would be 300W to each.

[ValveCoverGasket]

Ill include the Kicker KXMA1200.2 (if you can find one right now) in this same statement, but at a lower investment.

is it worthwhile at all to consider the A/B kicker amps?
it seems like the "X" models are the newer D, but crutchfield and other places still seem to have the (i assume older design?) KMA series, or is that too outdated at this point to be worthwhile?

awesome info in this thread - lurking as i have a stereo redo on my list for this winter

[pmkkdx]

ok, I think I understand that with the 8 channel ... now same question on the NVX 2 channel, as it seems to get the 4 ohm the watts per channel is 300 and per speaker is 150 ... right?

NVX VAD8402 – 2 channel 840 watts RMS (what I currently have driving the 4x Rev8s)
Splitting the two channels to the 4 speakers, one channel drives a pair.
2 ohm gives 420 watts per channel (2x) or 210 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

[MLA]

hmmm ...

so copying from my above specs post ... how is the bridged 8 channel get to 4 ohm

NVX VAD8402 – 2 channel 840 watts RMS (what I currently have driving the 4x Rev8s)
Splitting the two channels to the 4 speakers, one channel drives a pair.
2 ohm gives 420 watts per channel (2x) or 210 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

JL M800/8 – 8 channel 800 watts, bridging 2 channels for each speaker
At 14.4 vdc:
2 ohm gives 100 watts per channel (x8)
4 ohm gives 75 watts per channel (x8)
4 ohm bridged gives 200 watts per channel (4x) or to each speaker

this is actually quite interesting to me although confusing at the same time

Because you are bridging a 4 ohm load with a rev-8. But because you are wiring the 4 ohm speaker across 2 channels, which is what bridging is, each individual chnl acts as if its got a 2 ohm load wired to it. See the specs;

2 ohm x 8 ( 8 chnl stereo) = 100W each. So if you added the 2 channels together, you get the 200W.
4 ohm x 4 (bridged) = 200W each. When bridging a 4 ohm load, you add the 2 ohm output together to get 200 to a single 4 ohm speaker.

[pmkkdx]

Yes, the rev-8 is now, and forever will be, 4 ohm. You cant change the impedance of a single speakers, but depending on how you wire two together and connect to a single amp chnl, you can present a different ohm load. Or, when bridging A single 4 ohm across 2 chnls, each of the 2 chnls now "see" a 2 ohm load.

In the case of your current 2 chnl and the proposed 8 chnl bridged into 4 chnls, boat amps would be presented with a 2 ohm load on ALL channels and delivering the same wattage to each each speaker.

No switch on amp, it detects the impedance wired to the output channels.

hmmm ...

so copying from my above specs post ... how is the bridged 8 channel get to 4 ohm

NVX VAD8402 – 2 channel 840 watts RMS (what I currently have driving the 4x Rev8s)
Splitting the two channels to the 4 speakers, one channel drives a pair.
2 ohm gives 420 watts per channel (2x) or 210 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

JL M800/8 – 8 channel 800 watts, bridging 2 channels for each speaker
At 14.4 vdc:
2 ohm gives 100 watts per channel (x8)
4 ohm gives 75 watts per channel (x8)
4 ohm bridged gives 200 watts per channel (4x) or to each speaker

this is actually quite interesting to me although confusing at the same time

[MLA]

I guess the difference between 2 vs 4 ohm is throwing me ... you state the Rev-8 are 4 ohm each ... so no matter what is connected to the Rev-8, it will be 4 ohm?

is there some kind of switch on the amp that determines 2 vs 4 ohm ... if not a physical switch, how does it determine?

so the current NVX versus the JL M800/8 would be 200 watts to each speaker ... is that 2 or 4 ohms?

Yes, the rev-8 is now, and forever will be, 4 ohm. You cant change the impedance of a single speakers, but depending on how you wire two together and connect to a single amp chnl, you can present a different ohm load. Or, when bridging A single 4 ohm across 2 chnls, each of the 2 chnls now "see" a 2 ohm load.

In the case of your current 2 chnl and the proposed 8 chnl bridged into 4 chnls, boat amps would be presented with a 2 ohm load on ALL channels and delivering the same wattage to each each speaker.

No switch on amp, it detects the impedance wired to the output channels.

[pmkkdx]

I guess the difference between 2 vs 4 ohm is throwing me ... you state the Rev-8 are 4 ohm each ... so no matter what is connected to the Rev-8, it will be 4 ohm?

is there some kind of switch on the amp that determines 2 vs 4 ohm ... if not a physical switch, how does it determine?

so the current NVX versus the JL M800/8 would be 200 watts to each speaker ... is that 2 or 4 ohms?

[waterlogged882]

From a wattage standpoint, the nvx xad41 is out as it will only deliver 100W rms to each of your speakers. Thats a 100+ reduction.

The JL M800/8 is 200W rms with all 8 chnls at a 2 ohm load. So same load and wattage as your current 2 chnl IMO, you will not see a return on investment to replace your working existing 2 chnl to go with the $1050 M800/8. Of course, this is presuming the amp is good, so we are just talking wattage. As noted before, to correctly bridge the 800/8, you need 6 RCA splitters and populate all 8 RCA inputs. A 2 chnl requires no splitters and only a single pair of RCA. 200W rms is just hitting the speakers RMS and you've got the amp running full bore to boot.

The SYN-DX2.3HP is going to net 100W rms MORE to EACH speaker for only $50 more then the M800/8. This give you whats called head room. The speaker is going to reach its potential without running the amp's gain to its max. Ill include the Kicker KXMA1200.2 (if you can find one right now) in this same statement, but at a lower investment.

Comparing built quality between JL and NVX, Powerbass, Soundstream, ect, is certainly a worthwhile topic. Comparing the build quality of JL to Wet Sounds and Kicker, is a wast of time IMO. They all build a quality product.

The Rev-8 are 4 ohm each.

Is there anything you do not know about stereos?

Always learn from your input.

.

[waterlogged882]

https://www.sonicelectronix.com/item-182869-Kicker-48KXMA12002.html

.

[MLA]

From a wattage standpoint, the nvx xad41 is out as it will only deliver 100W rms to each of your speakers. Thats a 100+ reduction.

The JL M800/8 is 200W rms with all 8 chnls at a 2 ohm load. So same load and wattage as your current 2 chnl IMO, you will not see a return on investment to replace your working existing 2 chnl to go with the $1050 M800/8. Of course, this is presuming the amp is good, so we are just talking wattage. As noted before, to correctly bridge the 800/8, you need 6 RCA splitters and populate all 8 RCA inputs. A 2 chnl requires no splitters and only a single pair of RCA. 200W rms is just hitting the speakers RMS and you've got the amp running full bore to boot.

The SYN-DX2.3HP is going to net 100W rms MORE to EACH speaker for only $50 more then the M800/8. This give you whats called head room. The speaker is going to reach its potential without running the amp's gain to its max. Ill include the Kicker KXMA1200.2 (if you can find one right now) in this same statement, but at a lower investment.

Comparing built quality between JL and NVX, Powerbass, Soundstream, ect, is certainly a worthwhile topic. Comparing the build quality of JL to Wet Sounds and Kicker, is a wast of time IMO. They all build a quality product.

The Rev-8 are 4 ohm each.

[pmkkdx]

yep, my head hurts ... but comparing apples to apples, below are comparisons ... how do ohms come into play??? 2 vs 4 ... is the quality really that much better? I am looking at this being the last time I need to upgrade this system. The guy last night kept stating the JL M800/8 would still be the best with best quality.

Below are specs from individual sites:
NVX VAD8402 – 2 channel 840 watts RMS (what I currently have driving the 4x Rev8s)
Splitting the two channels to the 4 speakers, one channel drives a pair.
2 ohm gives 420 watts per channel (2x) or 210 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

NVX XAD41 – 4 channel 1200 watts (false since 1200 watts is 1 ohm)
2 ohm gives 150 watts per channel (4x) or same to each speaker
4 ohm gives 100 watts per channel (4x) or same to each speaker

JL M800/8 – 8 channel 800 watts, bridging 2 channels for each speaker
At 14.4 vdc:
2 ohm gives 100 watts per channel (x8)
4 ohm gives 75 watts per channel (x8)
4 ohm bridged gives 200 watts per channel (4x) or to each speaker
At 12.5 vdc:
2 ohm gives 60 watts per channel (x8)
4 ohm gives 60 watts per channel (x8)
4 ohm bridged gives 180 watts per channel (4x) or to each speaker

Wet Sounds Syn-DX2.3 HP – 2 channel 1200 watts
Splitting the two channels to 4 speakers, one channel drives a pair
2 ohm gives 600 watts per channel (2x) or 300 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

Wet Sounds Sinister SDX2 – 2 channel 1250 watts
Splitting the two channels to 4 speakers, one channel drives a pair.
2 ohm gives 620 watts per channel (2x) or 310 watts to each speaker (4x)
4 ohm gives 400 watts per channel (2x) or 200 watts to each speaker (4x)

Kicker Kicker KXMA1200.2
Splitting the two channels to 4 speakers, one channel drives a pair.
2 ohm gives 600 watts per channel (2x) or 300 watts to each speaker (4x)
4 ohm gives 300 watts per channel (2x) or 150 watts to each speaker (4x)

are there other viable options? as I think this should cover all the previous recommendations from earlier in this thread.

[pmkkdx]

finally talked to one guy about the changes I suggested (listed on last page) to which he agreed with going to the Clarion or Fusion head unit would be a better choice but also considerably more money over the Kenwood. In discussing the amp to the towers, tossed out 2 ohm vs 4 ohm and sound quality ... my head started spinning again. More to follow later this morning when I can capture all those notes. So looking for the braintrust here for pro/con on 2 ohm vs 4 ohm on right amp to drive towers (if really needed over the NVX).

[pmkkdx]

thanks! I sent the above notes to my wife to go out to the guys that gave us quotes ... stay tuned.