Need advice on setting up my wakeboard tower audio

[Bronzefish72]

I have a 4 channel amp (see specs below) and 4 wakeboard tower speakers rated at 150w rms / 300w peak. I want to run the speakers in parallel (unless series is better). The speakers are 6.5" with 1" dome tweeter. I am not sure if my amp is proper for my intended setup and need to know if I should buy a 2 ch amp instead. Per the vendor I bought the amp from, I was told this amp won't work for my setup and I should purchase a high power two channel amp instead.

Here are the specs of my 4ch amp:

• CEA Power Rating: 260 Watts (4 x 65 Watts) @ 4 Ohms and 1% THD+N • RMS: 800 Watts (4 x 200 Watts) @ 2 Ohms • RMS: 2 x 400 Watts @ 4 Ohm Bridged Mono • Peak Power: 1600 Watts • Minimum THD at Rated Power: <0.05% • Frequency Response: 10Hz - 40KHz • Sensitivity: 100dB @ 1w / 1m • Damping Factor: > 200 @ 100Hz • Three 20 Amp Maxi Fuses • Dimensions: ( W x H x L ) 8.6˝ x 2˝ x 13.7˝

• Crossover Band-Pass Control • Fully Adjustable 12dB Bass Equalizer • 2 Ohm Stable Stereo • 4 Ohm Mono Bridgeable • 3 Channel Mixed-Mono Capable • Mute and Delay Soft Start System • High Level Input with Smart Auto Turn-On • Full IC-Controlled Protection Circuitry

Because the amp is rated at 4 ohms when bridged, I apparently can't run my 4 ohm speakers in a pair a parallel as that presents a 2 ohm impedance per pair. I would be doing 2 speakers in parallel, one pair for left and one pair for right (not doing all 4 in parallel to one channel.)

So can I safely bridge channels 1&2 for the left pair in parallel and then bridge channels 3&4 for the right pair in parallel? The vendor is suggesting I purchase a comparable output amp but with only 2 channels instead of 4. This leads me to believe I can only bridge one set of channels on this amp.

I currently have a pair of 14 awg wires pulled through the tubing of the wakeboard tower. I don't want to drill and pull 2 more wires as there are other existing wires I'm contending with. I realize 4 separate speaker wires would be the best route here, but it's not a practical solution due to wiring limitations. I called a local stereo shop and was told I can safely bridge ch1&ch2 AND simultaneously bridge ch3&ch4.

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[Doxquzme Premium Member]

Something doesn't mesh with the specs listed. Run all 4 off a single channel each of the four. You're splitting hairs (well watts) when doing anything else.

What is the amplifier?
What are the speakers?

What is the layout of the speakers? Dual r/l upper rail/canopy, all four corners? Pics of what you are going to does far as mounting them?

 

[Bronzefish72]

Running 2 pairs of 4 ohm speakers. Each pair wired in parallel, so 2 ohm impedance. Alternatively, could wire series if I have to.

The amp is Rockville Phenom RXMF3

Speakers are Rockville WB65

I routed two speaker wires internally in the tubing of the tower, using 14 awg. So I have wires for a 2 channel setup.

It's a wakeboard tower on a boat (similar to a roll bar on a truck) so running all 4 in a row hanging from the tower's top cross bar.

 

[Doxquzme Premium Member]

Okay, kind of what I figured. Speaker separation is not a factor. The amp is only 2 ohms stable. you have only two options. One, run two pair in series then bridge the channels to the amp in a 2 channel operation (8 ohms bridged x 2) or just run a single channel to each speaker 2 channels Right, 2 channels Left.

That is it. Keep it simple, run a channel to each or get new 2 ohms speakers, you don't have other options with the equipment you have. THe amp is rated at 2x200 at 4 ohms bridged, you can't run this as you have 4 ohms speakers. the output at 8 ohms (series) is going to be about half the output or 100x2 so no difference than 4 at 65 watts.

The other option is as was mentioned, a high powered 2 channel amp that is 2 ohm stable or a higher output 4 channel that puts out at 4 ohms (better option)

VAD10004 1000W RMS V-Series Full-Range Class-D 4-Channel Amplifier (Marine Certified)

Product Details: NVX V Series Class D 2 ohms Stable 4-Channel Amplifier RMS Power Rating: 4 ohms: 150 watts x 4 channel 2 ohms: 250 watts x 4 channel Bridged, 4 ohms: 500 watts x 2 channel Total power output: 1000 watts CEA-2006 Compliant Amplifier Heavy-duty aluminum alloy heat-sink LED...

nvx.com

150 watts x 4 at 4 ohms.

 

[1aespinoza 10+ year member]

I routed two speaker wires internally in the tubing of the tower, using 14 awg. So I have wires for a 2 channel setup.

Is it difficult to run another set of wires? You could tie a string to the current wire and pull it out. Tie the two sets of wire and pull that string back through. I agree with Doxquzme, just use the Phenom at one channel per speaker. 65w RMS per speaker will be loud.

 

[Doxquzme Premium Member]

Is it difficult to run another set of wires? You could tie a string to the current wire and pull it out. Tie the two sets of wire and pull that string back through. I agree with Doxquzme, just use the Phenom at one channel per speaker. 65w RMS per speaker will be loud.

I use that really lightweight Oral B "Glide" Kevlar loose dental floss, **** it through with a vacuum on one end then tie the floss to the wire at the other end and pull it through. Works like a charm!

 

[Doxquzme Premium Member]

Another really GREAT option if you only have the two leads is something like this - reasonable at $179

VAD8402 840W RMS V-Series Full-Range Class-D 2-Channel Amplifier (Marine Certified)

Product Details: Marine Certified Full Range Class D 2-Channel Amplifier CEA-2006 Compliant Peak Power Rating: 1680 Watts RMS Power Rating: 4 ohms: 300 watts x 2 chan. 2 ohms: 420 watts x 2 chan. Bridged, 4 ohms: 840 x 1 chan. LED power (blue) and protect (red) indicators Conformal Coated Marine...

nvx.com

420 watts x 2 at 2 ohms

 

[Bronzefish72]

So to clarify, I can bridge ch1+ch2 for one pair of speakers, then bridge ch3+ch4 for the other pair of speakers. Is there a performance loss if I wire as series instead of parallel? I know there's an impedance difference, but is there a watts to speaker difference wired as series versus parallel?

Running 2 more wires isn't practical as I'd either have to drill out larger ports for the wires or run them on the opposite side of the wakeboard tower and string a bunch of wire to the other side of the boat. The tower is aluminum tubing and has a rope attachment point for pulling skiers, wakeboarders, tubes, etc. I don't want to compromise the structural integrity of the tower by drilling into it a bunch.

 

[Doxquzme Premium Member]

So to clarify, I can bridge ch1+ch2 for one pair of speakers, then bridge ch3+ch4 for the other pair of speakers. Is there a performance loss if I wire as series instead of parallel? I know there's an impedance difference, but is there a watts to speaker difference wired as series versus parallel?

Running 2 more wires isn't practical as I'd either have to drill out larger ports for the wires or run them on the opposite side of the wakeboard tower and string a bunch of wire to the other side of the boat. The tower is aluminum tubing and has a rope attachment point for pulling skiers, wakeboarders, tubes, etc. I don't want to compromise the structural integrity of the tower by drilling into it a bunch.

You can only run that amp bridged with the speakers wired in series (8 ohms a channel) That leaves you with about 100 x 2. You cannot wire the speakers in parallel as that gives you a 2 ohm load, the amp sees half the load in bridged mode so half of 2 ohms is 1 and the amplifier is not 1 ohms stable. Doing this would fry the amplifier. You can do it, series at 8 ohms a side, yes, it is the least desirable way to do it. Return the amp and get that NVX and run it at 2 x 400 watts to the 4 ohm speakers run in two sets of parallel wired sides (2 ohms each set to the amp per channel) R/L and you're golden.

 

[Bronzefish72]

So does that mean with this amp I can only bridge 2 channels? I assume that's why they are saying it's "bridged mono" on the specs.

 

[Doxquzme Premium Member]

Bridging is the combining (bridging) of two channels into 1. 2 channels into 1, 4 channels into 2, 6 channels into 3, etc.

In bridged mode, the amp sees half the speaker input load. A four ohm speaker is seen as a2 ohms speaker to a bridged channel. So two 4 ohms speakers wired in parallel (2 ohms) is seen by that bridged channel as a 1 ohms speaker, an 8 ohm load as 4, etc.

With four, 4 ohm speakers, you can;t wire them to 4 ohms a pair, it's either 2 ohms in parallel or 8 ohms in series or 4 ohms individually, which you don't want to run the wires to get that done, understand but that limits what you will be able to do.

One of these will trounce that rockville all day long and twice on Sundays and it is 2 channel 2 ohms stable high powered marine rated amplifier at $50 off regular price. You won't need additional wires to use it.

VAD8402 840W RMS V-Series Full-Range Class-D 2-Channel Amplifier (Marine Certified)

Product Details: Marine Certified Full Range Class D 2-Channel Amplifier CEA-2006 Compliant Peak Power Rating: 1680 Watts RMS Power Rating: 4 ohms: 300 watts x 2 chan. 2 ohms: 420 watts x 2 chan. Bridged, 4 ohms: 840 x 1 chan. LED power (blue) and protect (red) indicators Conformal Coated Marine...

nvx.com

 

[Bronzefish72]

OK, I didn't realize that a 4 ohm speaker is seen as 2 ohms in bridge mode. So then wiring 2 four ohm speakers in series would be seen as half of 8 ohms in bridge mode (aka 4 ohms)?

So then could I bridge ch1+ch2 for a pair of series wired 2 four ohm speakers? Then do the same for ch3+ch4 for the other identical pair, wired in series?

 

[Doxquzme Premium Member]

Yes, that could be done. The amp will put out about 100 watts x 2 (split to 4 so about 50 x 4) in bridged mode to both sets wire in series or roughly the same as it would if you ran all 4 on a single channel in 4 channel mode. That leaves a lot of volume on the floor as those speakers are rated to 3 tims that level or about 150 RMS a speaker. 150 watts is about 40% louder than 50 watts and on a boat, that is significant.

 

[Bronzefish72]

Yeah, thinking I'm going to ditch my 4 channel amp. Unfortunately, I can't return it. I may have use for it down the road in something else.

 

[Doxquzme Premium Member]

Better now than later