FWIW, Arc recommends setting gain with the small indicator **** on the gain dial pointing between the letters "a" and "i" in the word "gain" on the amp.

Again, FWIW, I have the Harman Kardon head unit, Arc 125.2 amp, gain set as described, Infinity Reference 2 ohm 6.5" speakers and listen to CD MP3 music at 4 or 5 bars on the volume setting while riding.

Keeping your 4 ohm speakers won't hurt anything. If you check Arc's website, the 125.2 amp is rated at 125W per channel @ 2 ohm, and 70W per channel @ 4 ohm. Using 4 ohm speakers simply means that you'll need to run the volume setting at a moderately higher level on the head unit than you would with 2 ohm speakers.

Check the gain setting. It's essentially a potentiometer so the lower the setting the higher the head unit volume setting for the same sound level out of the speakers; but, set too high, you have very little adjustment of volume through the head unit. Try Arc's recommended gain setting described above.

Carl

 

I gotta agree with Carl. Nothing wrong with the speakers you have now unless the higher indicated volume setting just drives you nuts. Like I said, I have 4 ohm speakers and have to turn the volume up to 23 or so on my Kenwood. Not sure if 30 is max or what, but it's as loud as I ever need it to be.

Now, if sound quality is the issue and I mis-understood your initial post..... Not much help there since sound is relatively subjective and, IMO, it will never sound as good as in a cage.

 

Wiring two 4 ohm speakers in series (+ radio channel wire to speaker #1 + terminal, and then a separate wire from the speaker #1 - terminal over to the + terminal of speaker #2 and then a third wire from speaker #2 - back to radio channel) will result in an 8 ohm load. The sound will be really poor.
I believe someone stated that wiring 2 4 ohm in series would put the ohm load at 2. To get a 2 ohm load with two 4 ohm speakers, the speakers will need to be wired in parallel, but the sound will be mono. Parallel is wiring the + wires together and connecting to radio channel +; then wiring the - wires together, and connecting to radio channel -). If the amp is not rated for 2 ohm load, it will tend to overheat.

My $0.02 worth... Good luck...

 

Yeah, you are right. It's been quite a while since my boom boom days of college. Series wiring increases the ohms and parallel decreases them. I had 4 10" subs that were wired parallel (8 ohms each) and presented a 1 ohm mono load to the amp when bridged. It got really hot, but was rated stable at 1 ohm mono and never had a problem.

Anyway, thanks for calling my attention to that.

 

Ohms = measurement of electrical resistance. Less resistance = more power.

You have 4 ohm speakers. Wire them to the 2 ohm posts as depicted in your manual.
In this configuration you will be pushing 75W to each speaker. More than enough usually.
I would look at your gain settings like the others already mentioned.

If you wanted to output 125W per channel you have two options:

1) Return the 4 ohm speakers and buy a set of 2 ohm speakers. Wire them to the 2 ohm posts on your amp. The End.

or

2) Buy another set of 4 ohm speakers and wire them in parallel with the other set of speakers.
Two four ohm speakers wired in parallel per side = 2 ohm. Wire them in series = 8 ohms.
Regardless, I doubt you have enough room for 4 speakers so I'm thinking you should go with option 1.

Again, 75W is usually plenty. Check your gain settings and ensure the Filter is set to FULL.

Also "Bridging" an amp is what makes it MONO. Running speakers in parallel is still stereo...well as long as you are still running two sides/channels.

lp

 

I was going to say something to all those who don't understand the affect of series vs. parallel connections on impedance. But, I see that their inaccurate descriptions of what happens when impedances are connected in series or in parallel have been corrected.

 

I can't take those speakers back. I'm just going to purchase some 2ohm speakers and put these Alpines up for sale.

Now the question becomes, which speakers do I get?

One more thing, these speakers I have are components so I have the tweeters in two of my open gauge holes ('09 EGS), would there be any way to keep them just to add more to it? I guess I could essentially just wire them to the radio instead of the amp correct? I need to take a look at the Alpine head unit manual to see if I can control the bass to just the tweeters if wired to the radio.

 

You could probably do that, but I think you would need a high pass crossover installed (unless the head unit has one build in) to filter out the mid-low frequencies. There are many different kinds of crossovers, but you would probably want to get the passive inline ones for simplicity and space savings.

 

Took the plunge and ordered the J&M 2ohm 7.25's today. By what I have read in this thread, they should provide more volume because they are 2ohm instead of my current 4ohm Alpines.

 

About 2ohms. Impedence rating of the coil in the speaker. Half as many ohms draws twice as many watts from the amp. Make sure your amp is rated for the impedence rating of your speakers. All else being the same as far as speaker ratings I doubt you would hear a difference.