I just installed the JBL GTO628 (2 Ohm, 6.5") speakers in my '08 Electra Glide Classic. Right now I'm running them off my HK radio.

The issue I have is it seems like I have to have the volume all the way up to get the same volume from the JBL's that I did at 1/2 volume from the factory 5.25" speakers.

Any ideas on the volume? Is it just because they are a larger speaker and require more power?

I realize they will sound better with an amp and probably require less radio volume setting. I'm waiting for an amp until I add rear speaker pods (which will be later this summer).

 

Bigger speakers need more power to move the voice coil, I don't know what the HD Head Unit putts out but those speakers are rated 60watts RMS 180 peak. Most head units are around 20watts RMS. Not enough juice to drive them.

 

That is what I was thinking. The OEM radio is rated at 20 watts RMS per channel.

Is there a way to run a 4 channel amp only using 1 set (left and right) of line inputs to power 4 speakers?

 

Yes you can.

 

Just using 1 low level converter to RCA and 1 RCA cable? I assume that will not allow the fade option (my radio doesn't have it anyway).

 

On that particular model you might want to check the polarity. When I had mine way back when, JBL had the polarity reversed. Just reverse the wires and see if it makes a difference.

 

Reversed wires make no difference.

 

I went ahead and ordered an amp and the rear pods to see if it makes a difference. Hopefully the amp makes a great difference. I went with a Clarion XC1410. It is 75watts RMS x4 with 2 Ohm speakers.

 

I've got a bud with 4 of those JBLs and that amp and it sounds pretty damn good. Those JBLs don't pack much bass but are clear and crisp.

 

That is good to know.

I'm going to use the OEM 5.25" speakers in the rear pods for now. I will upgrade them to the JBL's when I can.