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Double Bass Loss in bottom and volume when second cab added

Matt Ides

Matt Ides

May 12, 2004
1,860
420
Minneapolis, MN
www.youtube.com
#1
So I found a deal on a second GB 8T so I figured I would pick it up to have when I needed a bit more power and volume. When I add the second cab there is a significant loss in the low end and volume decreases as well. I assume this is not normal and the opposite should be happening. Each cab by itself sounds great, but together, YUCK. I have always been a combo or 1 cab and head player. So am I missing something here?

FYI: please move to the Amps section.
 
#2
it could be that one of the cabs is out of phase.
i am not an expert, but a similar situation arose with my buddy`s two cabs and one was out of phase.
he found out that one of the cabs`drivers had been repaired and when they wired up the speaker, they wired it backwards. he reversed it and presto!
 
#4
Just reverse the connections to only one of the cabinets.

You might want to check the cables first. It's possible that they are wired
reversed from each other. Otherwise, reverse the connections to the cab's
input jack.
 
#6
The most noticeable traits of an out of phase condition is having less bottom and volume when adding a second cab. Fix/test this theory by reversing the wires to just one of the cabs (use an old speaker cable you cut in half to test with just swap the wires at the splice to test) and try again. One way will be noticeably louder and fuller (more bottom) than the other. Once establishing which way is right make the change in polarity (permanently) as suggested at the jack dish of one of the cabs. It does not matter which cab is changed as the cabs are suspected of being out of phase with each other so changing either one will put both cabs "in phase" with each other.
 
#7
You could try the battery test on the cabinets before re-wiring, just to make sure they are out of phase.

Plus your speaker cable into one of the cabinets. Apply the terminals of a 9 volt batter to the other end of the speaker cable, say positive to the tip and negative to the barel of the jack (you need a 1/4" speaker cable for this, not a speakon). Watch the speaker cone in the cabinet and see whether it pops out or moves in. Repeat on the second cabinet, if it doesn't move the same direction, then they are out of phase.
 
#9
All that matters is that they both move alike (as bassmeknik said). The easiest test is to reverse one and check how they sound. You can even face them right towards each other inches apart. That will make the constructive or destructive interference (in or out of phase) very apparent.
 
#10
HolmeBass said:
You could try the battery test on the cabinets before re-wiring, just to make sure they are out of phase.

Plus your speaker cable into one of the cabinets. Apply the terminals of a 9 volt batter to the other end of the speaker cable, say positive to the tip and negative to the barel of the jack (you need a 1/4" speaker cable for this, not a speakon). Watch the speaker cone in the cabinet and see whether it pops out or moves in. Repeat on the second cabinet, if it doesn't move the same direction, then they are out of phase.
Click to expand...



+1 This will also allow you to check that the individual drivers (multiple driver designs) in each cab are also in phase. Carefully watch the direction of movement of EACH driver in your rig when connecting the 9 volt battery and make sure they all move the same direction together. You will be pleased with the results of your work the difference is obvious when A/B testing.
 
#12
Thanks for the replies everyone. I am to simple minded just to assume they would work since it is the shuttle 3.0 8T w/ the 8T ext. that was made for it. I tried upright, electric, and aux in all with the same result. I'll take your suggestions for testing to make sure they are out of phase, but that seems to be the case.
 
#15
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