4 subs installed, only perring 2. Why would 2 be louder than the other 2?

[WOT]

Just curious. One of my txa 1000D's gave out in my 4 15's setup. So only 2 subs were getting power. I completely removed oneamp, wet without bass for a while, then said might aswell put one back in and power 2 subs til the other amp gets fixed.

Well when I hooked it up to the firt set, it didnt seem very loud, so I hooked it up to the otherset of speakers and it was MUCH louder. My box is subs back port up in an suv, and the subs that were the loudest were on the highside of the front of the box. I didnt think there would be a HUGE noticeable difference though, or if something was wrong.

BTW, box is 17 cubes single chamber, 38hz and 230" port area....

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[helotaxi 5,000+ posts]

Not good to only power half the subs in a single chamber box.

 

[WOT]

I know, Im not running it on songs at all, I just felt like testing, thought Id post up the results and see what was said

 

[DidUHearThat? 10+ year member]

You might want to double check the mechanical movement and ohm load of each of the drivers in the quiet pair. Double check your wiring and examine the tinsel leads.

It could be as simple as the relative distance from the driver to the port changing it's output. The other pair of drives might be at a distance to the port that is more efficient.

Or it could just be minor differences in the way they were made or have worn over time.

If they all check out okay, I suggest you connect all of the subs together at a higher ohm load to run them off of one amp (i.e. 4-8 ohm instead of the usual 1-2 ohm or what ever you usually run). The increased cone area should make up for the reduced efficeincy in the amp ohm load operation. You'll get twice the cone area, but half the power, till you get your other amp back. Much better than no subs.

When powering 2 drivers out of 4 in single chamber cabinet the other 2 act as passive radiators and add load to the 2 powered drivers.

 

[WOT]

How do you check the ohm load? There DVC 4 ohms so Ive got each set wired to 1ohm, I used to have all 4 wired to 2 ohm but busted that amp so went back to the 2 amps and seperarted the drivers, So Ive oly got 2 + and 2 - connections coming out of the back of the boAnyway to check it like that?

Like its a night and day difference between the two drivers SPL wise, they both sound sloppy cause of the huge box there in im sure. But the difference is t much for me not to thinksomething else is up,,,,, but they work... the do make bass... so i dont get what could be wrong..

 

[WOT]

bump for some weekendtrouble shooters

 

[helotaxi 5,000+ posts]

It could also be that the different pairs load differently in the vehicle. I wouldn't take anything that happens with them in a box 2x the size as normal as indicative of actual performance. I really wouldn't be too worried about it.

 

[DidUHearThat? 10+ year member]

Just a thought.... Double check to make sure one of the quiet subs isn't out of phase. That would cause a "night and day" difference you describe.

 

[WOT]

and how do you check that

 

[IDSkoT 5,000+ posts]

Take out the sub and make sure they're wired correctly, depending if they're wired in series or what. I'm not really sure how you wired up your subs so I can't really tell you.

But, out of phase, for instance on a single voice coil sub / speaker, it would be out of phase if the positive wire was connected to the negative post, and vice versa. So make sure your ish isn't backwards 'cause that really does impact it... and, as shown before, when it is out of phase,they wear faster and are more likely to burn out because you'll turn it up too much, it's still getting the same amount of power as if it were in phase, but moving a lot less, and BOOM. There goes your sub.

And to check the ohm you need a DMM (Digital Multi-Meter). A DMM is a man's best friend.

 

[DidUHearThat? 10+ year member]

Another way to test phase, if you don't have a DMM, is to unhook the speaker cables from the amp and connect it to a small 9 volt battery. The drivers will jump together in the same direction. If one of them moves down instead of up, then you know that one is out of phase with the others. They should all move in the same direction at the same time. That means they are "in phase" with each other.

You could also use the little battery to test each voice coil, by attaching it to the VC one at a time, to be sure they are all working the same.