I just bought these jbl speakers, they should rock

[Jimmytee]

2 Ohms is quite a load - that why they can boast the power rating they do.
1. I would make sure that the amp is capable of a 2 Ohm load. Not sure where to find that out.
2. Do not daisy chain these speakers in parallel- that would give you a 1 Ohm load and will in all likelihood blow the amp.

So some quick "Weapons of Math Destruction:"
To get a 2 Ohm speaker to 55 Watts, that requires a 3.7 amp current at 10.4 Volts.
To get a 4 Ohm speaker to 55 Watts, it only requires 1.85 amps but 14.8 Volts - much less of an amp requirement.
To get an 8 Ohm speaker to 55 Watts, it takes less than 1 amp, and 21 volts.
Obviously the amplifier must be up to task for 2 Ohm loading.
If an amplifier at "full-tllt-boogie" is driving two, 2 Ohm speakers to 55 Watts, not counting electrical losses, that's a 7.4 amp requirement on the bike's electrical system.
I do not know what the OEM spec amp is capable of, even though the Fuse Box has a 40A fuse in the "External Amplifier" slot - don't know if that's the Sound System or something else.

I guess my recommendation is get all the info you can and just be careful.
JimmyTee has very valid points as well. Neos are very lightweight and pack a punch.

The 2 ohm load was my first concern. My experience with the OEM amplifier is that it didn't like a 2.7 ohm load let alone a 2 ohm load. You have to also consider that these impedance ratings are with the cone at zero. As soon as the cone/driver moves the impedance changes and can often dip well below the nominal rating when the cone is at full excursion.

[53driver]

The 2 ohm load was my first concern. My experience with the OEM amplifier is that it didn't like a 2.7 ohm load let alone a 2 ohm load. You have to also consider that these impedance ratings are with the cone at zero. As soon as the cone/driver moves the impedance changes and can often dip well below the nominal rating when the cone is at full excursion.

Jimmytee - do you know if that 40A fuse is for the OEM amp?

Edit: Just found it - yes it is.

[stroguy]

Few thoughts:

2. Anything above 15KHz is usually inaudible to anyone over 40 years old,

I'm 50 and I can't see some keyboards.

Good information here.....thank you gents.

[Jrockr]

You guys are good at this better than me. Also, you did convince that I should do a dry fit sound check first. I just wanted to go a different route than anyone else because of the speaker choices that we have. I will do more some shackles into it if I have to, not a big deal. Everyone on here is like a neighbor down the block coming in the garage to help me out!! Really cool

[53driver]

Okay, I did some phone calling....and I have reason to believe it's true, and you will never see this number published, but the OEM amp could only be 8 Watts a side.
No wonder they can get away with 14 gauge wire!
Putting in "55 Watt" speakers won't get you any more volume unless the Sensitivity is higher than the OEM speakers.

Thread relevancy: So these JBLs have a rated Sensitivity of 91dB.
Let's assume that the amp CAN run a 2 Ohm load (big assumption).
For the same amount of Volts and current that the OEM amp is capable of producing, if the Sensitivity of the OEM speakers is 88dB or less, you should hear one "noticeable" volume increase. For each 3dB difference in Sensitivity, there will be a noticeable increase.

More data:
When the average human ear detects an increase or decrease in sound pressure, that's a 3dB change.
Each 3dB increase requires a doubling of power.
I doubt the OEM speaker sensitivity rating is below 88.

Jimmytee - you measured the resistance on the OEM speakers and they were 4ish?
So the amp at 8 Watts into 4 Ohm speakers is about 1.4 amps and 5.7 Volts per side.
Into a 2 Ohm load, that would try to hit 16 Watts with the same amp and voltage. Something is going to give out...and do it unceremoniously.
Conclusion: this amp is only rated at 8 Watts into 4 Ohm speakers, I wouldn't think about putting in 2 Ohm speakers.

Bottom line: I NEED to upgrade this system on my bike.

[Jimmytee]

Someone had posted somewhere they had heard or read that the OEM amp was rated at 80 watts per channel. My testing calls BS on that one. No way is the amp that powerful. Looking at the OEM amp though, it is fairly hefty. 8 watts x 4 is hard to believe as well. What I can tell you is that I'm pushing probably roughly 80 watts per channel up front and the difference in output is substantial . As measured with a sound pressure meter.

[53driver]

Someone had posted somewhere they had heard or read that the OEM amp was rated at 80 watts per channel. My testing calls BS on that one.

80? No way. I know 80 Watt sound. This ain't it.

[98valk]

Okay, I did some phone calling....and I have reason to believe it's true, and you will never see this number published, but the OEM amp could only be 8 Watts a side.

Hi Guys,
This is all interesting stuff. But, 8 watts per side is a misunderstanding.

When I was adding rear speakers, I used an oscilloscope to see what the OEM amp was outputting. It will output 14v RMS! I realize in the real music world, that power will never be utilized, but it is there.

14v RMS into 4 ohms is about 50 watts. Even more into 3+ ohms.

If I get a chance today, I'll snap a pic of it on a scope.

[98valk]

Okay, here are some o'scope pics into a 4 ohm load.

Interesting thought. I have read several times in different places that this is an 80 watt/channel amp.
With 13v rms, you would get 80 watts into a 2 ohm speaker. Maybe this amp is rated for 2 ohms?! Sure would be nice to know ....



Attachment 13329
Here is some random music over the radio. No where near clipping yet.


Attachment 13327
Here is a 10khz sine wave just starting to clip above 18v.

That is only about 13v rms. Maybe my battery was more charged when I saw 14v, or maybe I was seeing what I wanted to see. Either way, there is a decent amount of power out of this OEM amp.

[DaWadd]

Great info.