What the heck? One subwoofer is louder than 2?

[flyboy1294]

Hey guys, here is my situation:

I have a Boston Acoustics GTA-1105 amp (http://www.crutchfield.com/p_065GTA1105/Boston-Acoustics-GTA-1105.html?tp=35808). It is suppose to be able to put out 400RMS at 2ohms on 1 channel. My old setup was a Kicker CVR10 with 4 ohm dual voice coils wired in parallel to 2 ohms. I was very happy with the system over all, but decided to upgrade for more bass.

Now I have the same amp, 2 Kicker CVR 10's with 2 ohm coils and a dual down firing box. I wired both voice coils in series, so each sub had an impedance of 4 ohms, and then wired the subs in parallel so the final impedance 'should be' 2 ohms. Well I fired everything up and I was extremely disappointed. It actually seemed quieter than my old setup. I double checked with an ohm meter, and I was getting a final load of 2.3 ohms for both speakers.

Well tonight I got frustrated and took everything out and tested it with an ohm meter again. Each sub was at 4ohms. When wired in parallel, they were around 2 ohms again. Then, just out of curiosity I unhooked one of the subs and wired the amp directly to a sub at 4ohms. I was AMAZED. The bass was incredibly loud and had no distortion or anything. I also noticed that the sub that was not hooked up was also moving because of the powered sub sharing a box, I assume.

So here is my question, why is 1 sub at 4 ohms louder than 2 subs at 2 ohms? That 1 sub should only be getting 200 watts RMS, but the two should have been getting 400 RMS. It just doesn't add up. There is a possibility that some of my connections were not perfect ( I did use those crappy terminals that have the spring loaded clip on the outside of the box, unfortunately) but the ohms ratings would not lie, would they?

Please feel free to offer any insight.

 

[Marcos]

Kicker likes more air space, so I think its because the kicker is getting the air it wants with just one sub hooked up, it sounds better.

 

[jdyates]

Maybe your amp can't power both subs. I had a kenwood amp that could only power 1 15" my brother had in a dual 15" box. When i bridged them or connected them R/L, the amp would shut off when too much bass hit, then turn back on after a few seconds. Try bridging them. I am by NO means a sounds expert (took us two days to wire in my amp), just an idea.

 

[Wagonbacker9]

very likely this is as simple as efficiency. Just because its rated for X power doesn't mean it is efficient. Plus the new subs may require more power to light them up. I would bet you would be even happier with a single sub in its own sealed box, as right now your passive radiator (which is what the 2nd sub is functioning as if it shares a chamber) may actually be hurting you.

Proof positive that more != better. That is unless you want to pick up another amp to light up the 2nd sub... and even as was said, if the sub is looking for more cubes than you can offer to the pair, this may not give you the gain you're looking for.

Maybe your amp can't power both subs. I had a kenwood amp that could only power 1 15" my brother had in a dual 15" box. When i bridged them or connected them R/L, the amp would shut off when too much bass hit, then turn back on after a few seconds. Try bridging them. I am by NO means a sounds expert (took us two days to wire in my amp), just an idea.

you were most likely wired below the rated impedance (ohms) of the amp.

 

[flyboy1294]

Everything said so far makes sense, and I tend to think everyone is right.

I have noticed the amp getting hotter. Before it would just be warm after cranking high volume for hours. Now it gets uncomfortable to the touch. Probably not a good sign.

Even though it is a 5 channel amp, the sub channel is mono. The other 4 channels are 75 watts rms and cannot be bridged to the sub unfortunately.

Wagon, how could this passive radiator be hurting my bass? I have heard of the term before, but I do not totally understand how it affects everything.


Thanks guys!

 

[Mean Green]

I would agree with the above statements also. As you have noticed, your amp is working a lot harder now then it was with the previous set up. IIRC the 10" cvr's require right at about .75-1.0 of air volume per driver minimum in a sealed enclosure, so the required air volume for a ported enclosure is generally quite a bit larger! So another factor of the problem may be lack of available air space. The enclosure is a HUGE factor of how the driver performs!

If your looking for more output, you might want to look into a single woofer set up in a large ported enclosure due to space limitations. You could even utilize the entire area under the rear seat for a ported enclosure with more air volume! Maybe take a look into the solobaric series sub woofers, they put out pretty impressive numbers! You would most likely have to look into getting a dedicated amp for a solobaric, but it may be your best bet for more SPL output! That's my input anyway!!

Sent from my Motorola Bravo

 

[Chris6060]

Kicker CVR's are a 400 watt RMS and each one requires atleast 0.8 cubic feet of air space. My CVR 10 has about 1.5 Cubic feet and it sounds perfect.

 

[jmc1997ck]

If the subs are not in phase with one another, they will destructively intefere or even partially cancel eachother out. Double check connections (polarity). A/B'ing one sub at a time will also confirm if thats the case...

 

[sewlow]

I would agree with the above statements also. As you have noticed, your amp is working a lot harder now then it was with the previous set up. IIRC the 10" cvr's require right at about .75-1.0 of air volume per driver minimum in a sealed enclosure, so the required air volume for a ported enclosure is generally quite a bit larger! So another factor of the problem may be lack of available air space. The enclosure is a HUGE factor of how the driver performs!

If your looking for more output, you might want to look into a single woofer set up in a large ported enclosure due to space limitations. You could even utilize the entire area under the rear seat for a ported enclosure with more air volume! Maybe take a look into the solobaric series sub woofers, they put out pretty impressive numbers! You would most likely have to look into getting a dedicated amp for a solobaric, but it may be your best bet for more SPL output! That's my input anyway!!

Sent from my Motorola Bravo

Check the boxes listed in the initial posting of this thread. http://www.gmt400.com/forum/showthread.php?7471-The-Subwoofer-Box-Thread

 

[1low95GMC]

i have two 10 inch dual coil kicker cvr's wired to 2 ohms on a 900 watt "spl" amp bridged behind my seat and it is very loud. you probably need a bigger amp to push them