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Need help with very strange amp/cab problem

banditcosmo

banditcosmo

Jul 12, 2002
1,148
275
Charlottesville, Va.
#1
I just got a new LDS 15/6 cab and it sounds great and have used it the last coupe of days with no problems.

Tonight I connected my G-K MB2-500 amp to it and when I do the amp makes this loud steady clicking noise and the power button flashes with the click. The clicking happens whether a bass is plugged in or not. When I plugged my other cab into the amp (by itself) the amp works fine no clicking. The clicking still happens with both cabs plugged in. I've tried both a speakon and 1/4" cable with the same results.
Then when I plugged my Markbass LMT800 into the LDS cab there was no clicking noise and it sounded normal.
What the heck is going on ? I'm at a loss.
 
#5
The crazy thing is the LDS cab works fine with the LMT800 amp and the G-K amp works fine with my other cab. Also on Sat the G-K amp worked with the LDS cab. This just started last night. I did take the LDS to practice so maybe something happen when it got moved around ? Really strange and hard to pinpoint.
I emailed Don at LDS to see if he has any idea's. I'm going to email G-K to see what the noise means. I think like B-String said it may be some kind of overload protection.
 
#8
Ask LDS to draw a full schematic of the cab, including drivers and crossover components, with ALL values and with ALL part numbers so specs can be independently verified. Have them email that drawing to you. Now you forward that drawing to G-K, and they'll duplicate that circuit on their test bench. Call them first and get their okay. Then they'll connect an MB2-500 and they'll see if they can duplicate the problem. I guarantee you G-K will want to know about this.

EDIT: I withdraw this advice. I missed the fact he'd run this amp with this cab successfully at least once before. Apologies to the board.
 
#9
Well now I really don't know what to do. I talked to Brian at G-K and he said it's not the G-K amp that's causing the sound , it has to be the cab. Don at LDS says it's not his cab it's the amp. Well the noise is coming from the cab so I'm thinking that it has to be the cab. I tried a 3rd cab and it works fine with the amp.

Here's a sound file of the noise it's making.

[Invalid or Expired Link Removed]

Anyone heard a noise like that before ?
 
#11
banditcosmo said:
Well now I really don't know what to do. I talked to Brian at G-K and he said it's not the G-K amp that's causing the sound , it has to be the cab.
Click to expand...

The cab don't make the sound when there isn't a speaker attached to it, cause it can't, has to be the amp.

You said it is in time with a flashing light, is the light normally flashing, but not usually making a sound? Is it some sort of warning light? Spent ages trying to figure a ticking sound coming out of an amp that only happened when a dude was playing his bass. Turned out to be his watch over the pickups.
 
#12
Mr. Foxen said:
The cab don't make the sound when there isn't a speaker attached to it, cause it can't, has to be the amp.

You said it is in time with a flashing light, is the light normally flashing, but not usually making a sound? Is it some sort of warning light? Spent ages trying to figure a ticking sound coming out of an amp that only happened when a dude was playing his bass. Turned out to be his watch over the pickups.
Click to expand...

But the amp works fine with my other 2 cabs.
The noise happens after the amp warms up and the light turns blue (takes 2 seconds or so) and the light does blink with the noise. The noise happens whether a bass is plugged in or not plugged in. Also I can turn the amp on without the speaker connected and the light does not blink (solid blue) but the second I connect the cab the noise starts immediately.
Also the noise happens even with the mute switch engaged on the amp.
 
#13
banditcosmo said:
But the amp works fine with my other 2 cabs.
The noise happens after the amp warms up and the light turns blue (takes 2 seconds or so) and the light does blink with the noise. The noise happens whether a bass is plugged in or not plugged in. Also I can turn the amp on without the speaker connected and the light does not blink (solid blue) but the second I connect the cab the noise starts immediately.
Also the noise happens even with the mute switch engaged on the amp.
Click to expand...

The amp is the power source for the noise, so possibly something in the cab is interacting, but the amp still has to be supplying the necessary energy. I don't have a great understanding of the internals, but I reckon it will be funny interaction with the crossover, since it is a true crossover, whereas the other cabs I'd guess are woofers, with a high passed tweeter. Mostly that's the only difference I can see between the cabs. Is the sound only coming from the mid or can you feel the woofer moving too?
 
#16
Still saying the protect circuit. There maybe a cold solder joint on the cabs crossover that changed the load seen by the MB2-500? If it worked before with the cab and now doesn't then something in the cab must have changed. If it never worked then I'd say the MB2-500 is the one not playing by the rules. :)
 
#17
I'm guessing something in the cab rattled loose or makes an intermittent connection that the amp perceives as a short, while the other amp doesn't. Open up the cab and check for loose components or cold solder.
 
#18
A few months back there was some discussion about a certain type of crossover that would interact negatively with a certain type of amp, and create some weird sonic phenomenon when paired together.

Unfortunately this is all I can remember about the subject, but maybe someone who's familiar will see this thread and chime in.
I almost remember one of the Genz Benz guys (Hasbeen or Agedhorse) might have provided the explanation, but I could be mistaken.

If the cab is fine with other amps, and the amp fine with other cabs, it has to be something unique like this.
 
#19
lbwdog said:
A few months back there was some discussion about a certain type of crossover that would interact negatively with a certain type of amp, and create some weird sonic phenomenon when paired together.

Unfortunately this is all I can remember about the subject, but maybe someone who's familiar will see this thread and chime in.
I almost remember one of the Genz Benz guys (Hasbeen or Agedhorse) might have provided the explanation, but I could be mistaken.

If the cab is fine with other amps, and the amp fine with other cabs, it has to be something unique like this.
Click to expand...

Thanks Dog, that seems like a possibility. I'll have to do a search to see if I can find that thread.
 
#20
lbwdog said:
A few months back there was some discussion about a certain type of crossover that would interact negatively with a certain type of amp, and create some weird sonic phenomenon when paired together.

Unfortunately this is all I can remember about the subject, but maybe someone who's familiar will see this thread and chime in.
I almost remember one of the Genz Benz guys (Hasbeen or Agedhorse) might have provided the explanation, but I could be mistaken.

If the cab is fine with other amps, and the amp fine with other cabs, it has to be something unique like this.
Click to expand...

Thanks again lbwdog, I found that thread.

problem with my shuttle 6.0: protect-circuit

Now I just need to wait for Don at LDS to reply to my emails to see what he says.
 

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