Distorted cab question

[UncleJimmy]

Hi all. I know this will be an elementary question to most, but I just can't seem to wrap my brain around certain gear issues.

I've noticed at a few recent gigs that my cab seems to have an ugly distorted sound after we've been playing for 45 minutes or so. This happens when playing with my louder rock band. I have had a gig in between with the lighter funk band with no issues. I am running a GK700RBII (320 W at 8 Ohms) into a Hartke HX115 (500 W 8 ohms). Volume,boost set at just over 12:00, low mids, bass at 1:00, high mids, treble about 2:00.

I would think the cab should be able to handle anything the amp throws at it as it is rated much higher. Is this correct? Are my settings causing this to happen or am I just pushing too hard? Have I blown the speaker?

Any opinions or feedback will be appreciated.

[Bass_Pounder]

Your 500 watt rating is the THERMAL rating only (point at which voice coil will melt). The physical limits are more like half that.

Also, many amps hit their max output of clean power long before your volume knob is maxed.

It is possible that you did some physical damage to the speaker (cone creasing, etc.) that only manifests itself at louder volumes.

Your "louder" gig probably needs more than a single 15" can provide.

[john m]

One possibility:

The voicecoil is getting a bit hotter with your louder band,
expanding, and rubbing on the supporting structure.

[RickenBoogie]

+1 spkr cab ratings are all but useless, and a 1x15 is hardly sufficient for a loud rock band. 2 of them would be much better, or maybe you need more than that, (?).

[billfitzmaurice]

Originally Posted by john m

One possibility:

The voicecoil is getting a bit hotter with your louder band,
expanding, and rubbing on the supporting structure.

If it did that it would blow. However, voice coils do get hot, and when they do the resistance of the coil goes up. This results in a loss of sensitivity, called thermal power compression. Very often the player will then turn up to compensate, making the coil go even hotter, with an even greater loss of sensitivity. This can spiral out of control, resulting in blown drivers. The cure is to double your driver count.

[jimcroisdale]

I know that I often get carried away as the gig goes on and hit the bass a fair bit harder.

If I'm already on the limits of my cab's volume (which I often am) this can certainly push it into distortion.

Jim