tower speaker diagnosis

So I was out on the lake the other day and I noticed my tower speakers (1 pair of Bullet Hollow Point 650 HLCD approx 2 years old powered by infinity amp approx 125x2) were not sounding as good as they used to. Further inspection revealed one of the tower speaker not functioning properly. I will try to put into words what I heard:

-quieter
-tinny
-empty
-highs only
-unable to make out any music

I checked the mid-bass driver and it was not moving. I trouble-shot the amp and wiring and ruled them out as the problem. Only thing left is it must be the speaker. I do not have the funds to buy a new pair. Any thoughts on what might be wrong or how to fix it? I will be contacting Bullet as well, but I know a lot of guys on here know their stuff. Thanks for the help.

-Kyle

Kyle,
It appears from your description that one of the midbass drivers is out. There is an internal passive crossover so one of the positive or negative wires could have come off either the crossover board or the midbass driver terminals. Simply pull the four outer screws, remove the speaker and grill and check the internal connections. There are four more connections between the crossover and tweeter that shouldn't interest you. While the polarity of all this is marked on both the speakers and crossover, please be cautious and take note of everything.
Manually see if the midbass driver is frozen so that it will not move. If that is the case it has been permanently damaged from heat (by too much power). If that is the case you will also notice a distinct burnt smell when you remove the speaker from the pod.
If you have a multimeter you can check continuity across the midbass driver terminals. You should get a DC resistance reading of between 3 to 4 ohms. If it reads 'open' then this is another indication of damage. If you don't have a multimeter then you can check the midbass driver by circumventing the passive crossover and jumpering the crossover input directly to the midbass driver. DO NOT try this technique on the tweeter. This will also eliminate or confirm the passive crossover has an issue.
You can also switch the left and right drivers while leaving the crosovers in place to isolate either the midbass driver or crossover.
Bullet has discontinued the HollowPoint 650 HLCD some time ago so replacements may not be available. If it comes to needing a replacement midbass driver only I may know where to find one among the dealer network.
Let us know how it goes.

David
Earmark Marine

Awesome I will get on that after the Holiday. Thanks!

I just checked the resistance of the mid-bass and the tweeter. The tweeter is showing 6.7 ohms while I am getting 0 on the mid-bass. Does this mean the mid-bass driver is shot?

The tweeter impedance is 8-ohm so a DC resistance reading of 6.7 is normal. If you have checked the midbass driver directly and independent of the passive crossover then an 'open' of 0-ohms would indicate a failed speaker. However, you may have missed something like an 'open' where the braided tinsel leads connect to the speaker terminal. So give it a thorough visual inspection before deciding to discard the midbass driver.
Before you start a search for a replacement you want to make sure that you do not have an existing issue with amplification that could carry over to the replacement speaker. The HP650 driver is very hard to damage so I'm a bit suspect given that its just one side. If you have a leaky transistor in your amplifier it could be sending DC current to the speaker. The tweeter would be protected from this condition by the series capacitor in the passive crossover while the series inductor in the lowpass section of the crossover provides no DC protection for the midbass driver.
Jamie with Bullet Speakers can do a voice coil inspection of the bad driver which can sometimes provide a tell. Or we can do the same.
At this point it would appear that you have narrowed it down.

David
Earmark Marine

What would be a good cost effective amp to drive them sufficiently? I have been contemplating a new amp for the towers. I will look closer at the speaker. Thanks again!

Kyle,
If you have a single pair of 6.5" HLCDs then you need a minimum of 150 watts per channel to each speaker. 200 watts per channel would even be better to always keep the amplifier running in a conservative mode. The most cost effective way to get this power is with a small to moderate four-channel amplifier that is bridged into two channels. This would be available from a number of good name brand manufacturers inexpensively. The amplifier would also have to have a variable crossover rather than a fixed crossover.
As for DC its impossible for a functional amplifier to impose a true DC signal on an AC waveform by over-driving the amplifier into clipping or compression. That has been a common myth. Its a misconception by people who misinterpret the appearance of a squared off AC waveform. However, within the specific context of a faulty amplifier with a defective part and in need of repair then its possible that the amplifier could pass a component directly from the amplifier power supply to the speaker. These are two entirely different events and two entirely different discussions. An expert knows the difference.
So Kyle, if your amplifier is working correctly you have nothing to fear. If your amplifier has a bad part then you don't want to carry this forward to a replacement speaker. A damaged speaker VC will provide a clue as will a few measurements on and a bench check of the amplifier.

David
Earmark Marine

Cool thanks!