2 broken 12" speakers in the same day with powerhead¡¡¡¡¡¡¡¡gggggggggggCAUTION

Ouch, that's bad! What is the Ohm-age of the cabs?

So you connect a 600W amp to a 100W speaker, crank it up and wonder why the speaker is blown? Seriously?
Don't get me wrong though, I feel sorry that you've blown some money. But you could have known better.

I don't think you're stupid, man. But I think you made a mistake.
One reason for this to happen is that you generated some spikes that were to much for the speakers. Maybe you had the Power Amp Booster at a low setting, allowing lots of headroom for hard attacks and transients ... as opposed to a higher Power Amp Booster setting which would lower the headroom by compressing the signal.
Read page 27 & 28 in the english Kemper Profiler The Basics and Profiling Guide ... or page 29 & 30 in the spanish Kemper Profiler The Basics and Profiling Guide.

Correct me if I'm wrong, but the Kemper power amp is putting out 600w total and you have a cabinet with TWO 100w speakers, so you have 300w per channel feeding one 100w speaker. Sounds like great clean headroom, but if you drive to distortion, you may blow the speaker.

Unless you have a limiter on it. Typically you play it clean, turn it up to where it just breaks up. But if you turn it past breaking, you may easily have a problem.

Now this is where it gets confusing for me. I had a 100w JCM 900, feeding a 4x75w half-stack. I was told that the 100w fed 4 speakers of 75w, or 300w of speakers. No overloading there. (All assuming the Ohms are the same for Amp and Cabinet here) But I was told this 100w was to get better headroom for a CLEAN tone, which I really liked, so good for me.

However, if I wanted MORE distortion than clean headroom, I should get an amp (same amp) with 50w instead! So less watts on the amp would have less clean headroom and drive the speakers to distortion much easier. I don't understand it, now lower wattage drives more distortion.

But that would lead me to think that 600w would have amazing headroom for clean tones, but not be as good as a lower watt for driving quicker and safer rock distortion?!? If that's the case, wouldn't a Camplifier be a better alternative?

Help me out folks. Tell me what I got wrong, and write (yes, a pun)

I remember reading somewhere that the KPA powerhead is "as loud as a 100-watt tube head" (can't find the correct thread right now, if it ever existed...). This doesn't necessarily mean that a 100-watt speaker would be ok though, but that number was given as a guideline for choosing a suitable cab. Or am I being misinformed here?

If the unfortunate event of the OP was exclusively due to a small wattage number of the speaker, then I would like to understand what is the minimum safe value. For instance, I have a 4x12 cab that is rated 240 W at 8 Ohms; is it safe to run the powerhead as loud as, say, the Peavey 6505 head I used to have (which was insanely loud already when the master vol was 3-4 or something like that)? I.e., should I trust my ears only or is there something else that comes into play? I got the impression that the OP tried to be careful in selecting the appropriate volume level.

Another scenario that comes to mind is that one might be forced to couple the powerhead to whatever cabinet there is on a, say, smallish venue for monitoring purposes. How to make sure that nothing explodes in such a case?

Quote from laardi

... one might be forced to couple the powerhead to whatever cabinet there is on a, say, smallish venue for monitoring purposes. How to make sure that nothing explodes in such a case?

Increase the Power Amp Booster parameter to reduce the headroom and thus potentially harmful attacks and transients.

Quote from db9091

However, if I wanted MORE distortion than clean headroom, I should get an amp (same amp) with 50w instead! So less watts on the amp would have less clean headroom and drive the speakers to distortion much easier.

No, not the speakers (we don't want speaker distortion!!) but the poweramp gets driven into saturation more easily because there is less headroom in a 50 W tube amp than in a 100 W.

Quote from db9091

But that would lead me to think that 600w would have amazing headroom for clean tones, but not be as good as a lower watt for driving quicker and safer rock distortion?!? If that's the case, wouldn't a Camplifier be a better alternative?

Help me out folks. Tell me what I got wrong, and write (yes, a pun)

With the poweramp of the powerhead/powerrack being as neutral as possible we don't want it to distort EVER (contrary to a tube poweramp). You're right about the amazing clean headroom the 600W poweramp in the powerhead provides.

Really sad situation, but, I think this time its user error under-estimating the power output.

Ouch. That must hurt. Your other guitarist must be mad at you.

I played my powerhead with the power amp boost at +10db into a Bogner 2x 12 cab 8 ohm for two months now, and no problem with the speakers this far ( Celestion vintage 30s )
A also played four times with the same volume into a 1x12 celestion 8 ohm vintage30 speaker with the same high volume and also that single speaker could take it with no problem at all.
If I want to go as loud as my Engl 1x12 8 ohm 100 watt amp I have to turn the power boost to max (+12db ) and still the celestion speaker takes it.

Sounds like you badly clipped the output of the Profiler. The heavyly clipped signal may have fried the speakers easily.

I think you just have to get used to the dynamics, the Profiler is capable to produce. When you adjust the volume while noodling a little bit on your guitar, you forget the peaks you can generate e.g. when you slap the low E-String hard. This can generate a peak in your speaker that fries it. So to prevent that you have to compress / soft-clip the signal before the power amp and that's what the Power Amp Boost does. It's not so important to do this with high-gain profiles because they're most likely compressed already. Much less dynamics there. But if you play a Bluesbreaker and you enjoy its dynamics picking from soft to very hard, then you certainly produce power peaks. The overall volume might still sound low, but the peaks can easily exceed the max. allowed load of the speaker. Hope you understand what I'm trying to say. The power amp can easily produce power peaks of up to 600W while you still think its overall volume sounds like 50W only ... without using the Power Amp Booster.

Quote from Dorrus

I played my powerhead with the power amp boost at +10db into a Bogner 2x 12 cab 8 ohm for two months now, and no problem with the speakers this far ( Celestion vintage 30s )
A also played four times with the same volume into a 1x12 celestion 8 ohm vintage30 speaker with the same high volume and also that single speaker could take it with no problem at all.
If I want to go as loud as my Engl 1x12 8 ohm 100 watt amp I have to turn the power boost to max (+12db ) and still the celestion speaker takes it.

Exactly, same here....I'm not sure why the OP had a problem.

Quote from estocastico7

thanks friend.probably it was that happen to me.I was playing with a clean profile in low volume,but suddendly in some notes,the sound disappear,and the speakers burn.....i think that power amp boost where a extra volume in cases that master volumen where insufficient.

jjjjjjjjj

In my experience you hear the amp distorting long before the speaker blows. it gets worse until 'poof', no sound and you smell something burning.

At least that's what happened to me back in the day, I was running a stereo tube amp (Mesa 290) and forgot to turn on one side at a gig. Maybe solid state amps react differently, never blown a speaker with one yet.