View Full Version : Help!! wiring amp to cabin speakers

02-16-2010, 11:10 PM
hi there i have a pioneer 760 watt amp and i want to amp my 2004 xlv's cabin speakers. since there are 6 speakers and the amp is only 2 channels how will i do this.. i know it can be done by the way

specs: RMS Power Range : 250-380 Watts
Number Of Channels: 2
Maximum Power: 760 Watts
Low Frequency response: 10 Hz
High Frequency Response: 50000 Hz
Built In Crossovers: Yes
Channel Separation: Yes

CEA-2006 compliant
RMS Power @ 4 ohm: 125W x 2
RMS Power @ 2 ohm: 190W x 2
RMS Power @ 4 ohm bridged: 380W x 1
Selectable low-pass filter (80 Hz, 12 dB per octave)
Selectable bass boost (0, 6, 12 dB at 50 Hz)
Built-in Crossover has selectable LPF
MOSFET power supply
Speaker- and preamp-level inputs
Fuse rating: 30A x 2
Total Harmonic Distortion only 0.015%
2/1 Channel # Capability
Screw-Type Speaker Terminals
Dimensions: 14-1/8"W x 2-3/8"H x 11-13/16"D

02-17-2010, 12:31 AM
While i'm no expert running six speakers off of a two channel amp is not a recommended method, especially in a boats environment were just keeping things cool can be a challenge at times.

If you series wire them you'll exceed the ohm's at something like 12ohms per channel i think. Parallel wiring will drop it to almost 1 ohm per channel and it doesn't look like a 1 ohm stable amp. Your much better off getting a proper amp for the job.

I'm sure our Stereo experts will chime in on this one.

02-17-2010, 01:27 AM
ok well what about the rear 4 speakers on the 2 channel amp.. lots of people have done this

02-17-2010, 11:13 AM
For three speakers a side, (six speakers total), you would wire a pair in series so that they show an 8-ohm load, then wire that series pair in parallel to a single speaker. That will show a 2.67 - ohm load to the amplifier. The two series speakers will get about 40 watts each, and the speaker that is in parallel to the series pair will get about 80 watts. Oviously, the two series speakers will be half as loud as the other one. This is electrically a real solution but it is far from ideal.

For 4 speakers only, you maybe can wire the speakers in parallel, two per amp channel. that mathematically will deliver 95 watts to each speaker. This is closer to a good solution, but it has its potential for issues... See below for my explanation of why you might run into problems.

A word of caution. Amplifiers commonly show 2-ohm stability these days... This started way beck in the day when we first started loading up amplifers with subwoofers, squeaking every bit of power we could out of the little amps; a 500 watt amp back then was a HUGE amp! Somewhere along the way, largely as a result of market share wars, everybody started building amps that were 2-ohm stable, just so they could advertise bigger power output numbers. This was driven by sales and marketing....

A new generation of mobile audio consumers today feed on the myths and partial truths propagated back in the heyday of car audio. The science is largely lost on a large number of us. So to that point, I provide you a few maxims. David at Earmark has some excellent exceptions to these rules, and he can cite an exception for most every case I present below, but for the majority of us, these are good guidelines to follow:

* Just because an amplifier is rated at 2-ohms is not an indication that you must run it that way. When designing your system, consider using one amp channel for each full range speaker. Save doubling up for the subwoofer section.

* When you are forced to run two full range speakers on an amp channel, realize that the NOMINAL IMPEDANCE of the speaker is 4-ohms, but in action the speakers are often really more like 3.6-ohms each. Two in parallel will result in a load of 1.8-ohms, and that will be too low for some amplifiers, causing them to shut down. In these instances, it is better to wire the speakers in series.

There are more maxims to share, but for this thread, I will leave them out, so I am not accused of a thread hijack! :)

My opinion and recommendation for you would be to consider a good multi-channel amp for the 6 speakers. Maybe even a 4-channel amp and 2-channel amp. You might find that your current 2-channel amp will work as that 2-channel amp, or you might consider using it as a sub amp... You have options, so I throw those recommedations out for ya!!!

You can wire the 6 speakers you have to your current amp, but I have a strong feeling that once you do so, you will be unhappy with the results. Try it, and let us know; I might be wrong... :D

Good luck!


02-17-2010, 11:32 AM
Wow thanks a ton for all that Info. It really helped. So if I get another 4 channel amp, and use my 2 channel amp, what size 4 channel amp do I need?

02-17-2010, 11:43 AM
Really, it depends on the speakers you are using. If your speakers are rated at 75 watts RMS, you can go with an amp that is AT LEAST 75 watts RMS. It is better usually to go higher in power by a little bit rather than underpowering...

Your current amp claims to deliver 125 watts per channel into 4-ohms, I would recommend finding a 4-channel amp that does the same thing into each channel... 125 watts per channel might seem like a little much, but the extra power gives you headroom, (the ability to run the speakers to rated power, and maybe a little more with clean non-clipped power) and allows you to set your gains LOW for less distortion and noise associated with the normal electrical clicks, pops, and buzzing we find in so many boats.

02-17-2010, 11:44 AM
You need to give them more info, what are the speaker brand? Model? What's the head unit? Do you have a sub? Tower speakers?

Phil, David and Brian are awesome and we're extremely lucky to have them here to guide us along with the stereo issues! :p

02-17-2010, 11:47 AM

You'll wire the two left cockpit speakers in series.
You'll add a 25 watt 2-ohm to 3-ohm resistor to the left bow speaker.
You'll tie the 6-ohm bow and 8-ohm cockpit circuits together in parallel. Same for the right channel.

This will balance the amplitude and provide a safe impedance load.

Or, a better option is to replace the resistors with an multi-step autoformer stereo volume control that you'll adjust and conceal away. The advantage is that the autoformer raises the impedance and attenuates the speaker via a magnetic medium without converting power to heat and thus is more efficient.

Earmark Marine

02-17-2010, 11:54 AM

See, David has a different way to look at it... I really apppreciate the insight he brings and agree that this solution is a good one...

Since Razz brought it up, what is the rest of the system?


02-17-2010, 02:38 PM
I must have missed this one last night. Sorry for being late to the party. After reading the thread I'll just let things be...Looks like everyone presented great info. I just hope he doesnt catch his boat on fire with that soldering iron and hand full of resistors. Muahhaha!

good info on here for all :)


02-17-2010, 04:06 PM

The 'fire' joke was probably in bad taste.

He told me he was only accused but never convicted of that arson charge. Besides, the insurance had already run out on that Bayliner anyway.

02-18-2010, 11:35 AM

I thought it was that old Glastron. Tri-hull Swinger model, right?

02-19-2010, 10:57 AM

It sounds like a classic but hey, if we're putting a stereo in a Glastron its my favorite boat of the day.

Earmark Marine