BillFitzmaurice.info

I have had some issues the past couple weeks with my Crown XTI 4k's

Tuesday last week.. setup at the gig running only half of my rig. Outdoor .. didn't need it any louder than that.

Using a single XTI 4000

Hooked to Channel 2 - Wired per plans -
1 - Shorty SLA Pro
1 - Tall SLA Pro

Hooked to Channel 1
2 - T39's 3012LF - Parallel

I turned the amp on and POP! Channel 2 went out.

I had to run the tops off the XTI 2002 I have for backup in the rack. No problems.

I have ran that amp with all 4 SLA's on Ch2 and all 4 T39's on Ch1 for about a year now without issue.

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I bought another amp Thursday .. XTI 4002 .. newer amp.

Tested it at home with all 8 speakers hooked to it. Seemed to run fine.

Get to the gig on Saturday.. it ran for 30 mins and then it shut off! Would not turn back on. It would start the boot sequence then shut off again. There was a spark inside the amp when I tried to turn it back on. Switched to the 2002 again. Sounded like crap compared to the 4002, muddy .. I didn't have the gain structure tuned for maximum output. I will do that now.

I ran the 2002 for the rest of the night. About 4 hours without any problems.

The 4002 is still under warranty so I will send it in.

I just would hate to get it back and it blow again for something wrong with my system.

Would loose wiring in the speakers cause this issue? I have tested all the ohm's and they seem fine... although they look low.

T39's are measuring 5.7 .. they are 8 ohm. I heard they go up when voice coil gets warm.

Is there a problem with them?

I have a Furman Power Conditioner .. would that cause an issue?

Thanks for any advice

LJ

DJ.LJ wrote: Would loose wiring in the speakers cause this issue?

It could, as could loose cable connectors.

T39's are measuring 5.7 ..

That's DC resistance, not impedance, and it's normal.

I have a Furman Power Conditioner .. would that cause an issue?

Maybe. They're totally unnecessary and can cause problems.

The early XTI 4000s had a known problem of not working well under a low power line voltage condition. But that typically just reduced power output. I doubt it could cause the channel to blow. Any chance your line voltage was low?

It seems like the new 4002 most likely had a manufacturing defect. The XTI amps have built-in fault protection which should engage if there is a problem with the speakers.

I prefer not to run an amp with a 2 ohm load. I know it's convenient to run all on one amp. But it is significantly harder on an amp because the heavy 2 ohm load draws twice as much heat-generating current as a 4 ohm load. Heat will definitely shorten the life of an amp. The XTI isn't a true class D amp, so it does tend to run a little warmer.

Bill Fitzmaurice wrote:

DJ.LJ wrote: Would loose wiring in the speakers cause this issue?

It could, as could loose cable connectors.

I'm going to take apart all the cable ends and check them today. People mess around behind the subs sometimes. I found a broken connector once a couple months ago.

It may be a bad power source. If you have a long extension chord of a light gauge going to a circuit that is being shared with several other things, the amps will sound distorted if they power on at all.

Meter your outlet and get the amps as close to the outlet as possible. Find a dedicated circuit and keep your run at 25' with 12-14 gauge or 50' 10-12 gauge power.

What exactly does the Furman do for your setup?

To reset the amp:

1: Unplug
2: Remove the top cover
3: Replace fuse by the power supply
4: Re-assemble and power up



I have had this type of issue a few times, but I have yet to see sparks.

Something sounds odd when you can power up everything at home without incident, then get a problem with half the gear on the same amp when out,especially when it worked like that for half an hour.

Did someone step on a lead about the time you got the problem?
Sure, check your connectors, but also check your leads for a short (With continuity tester on your multimeter, you will get a continuity tone if you put the probes on +1 and -1 for example, if a short condition exists).

Sounds like the amp went into protect mode and because the fault condition still existed with the cabs all hooked up, blew the fuse.

If you don't find a short or the fault isn't in the lead, then the problem could be in the cabs...

I have found one cable so far with a loose connection inside the speakon.

Maybe it could have shorted against one of the other wires inside. This is a 4 cable wire running 2 channels across the system. The first short was on just one channel of the first amp. That amp actually is displaying a fault of "short 2". Channel one is working fine.

At the gig I was moving cables trying to find problem so I may have temporarily moved the wire inside so that it did not short out the channel again because I hooked it up to the 2002 and it worked.

When the other amp went out... could have been the bass to jiggle the loose cable to short out that amp all together.

Baffled at this point.

I am going to continue to check the cables and then remove a speakon from one of the subs. It looks as though something was spilt down the back right over the connectors.

Would this still be a problem now that it is dry? Probably an alcohol drink of some sort spilled on it. People set drinks on them and I don't notice until it is too late.