advice on guitar spkr cab to use with KPA

    I am trying out a KPA right now. So far it is blowing me away!

    Unfortunately it also blew my Marshall cab. I was cranking the KPA trying to keep up with my lead guitarists 100w Marshall stack and ended up having to go almost flat out on poweramp boost, master and rig volumes while he was cruising at 3 on the master volume. Everything sounded good for a few minutes then the sound of silence happened. I checked my Marshall cab (that I normally use with my 50w head) and it smelled like burned electronics. Guess I am learning the hard way about watts and volume and amps and speakers. Turns out my Marshall 4*12 had 4*60w speakers and thus only supports 240w. My mistake, I just never had to think about that before.

    Anyway, I am looking for advice on what speakers to get for my cab now. The normal Greenbacks and V30's don't rate enough to support the 300w output of the KPA, so what are you guys using? I don't want to lose my vintage Marshall sound. And I really don't want to go FR speakers as I would like to be able to alternate between my Marshall head and the KPA using the same cab.

    And even though I've read about 100 articles on the subject now, can anyone REALLY explain why a 50w tube head at volume 6 is twice as loud as a KPA going flat out at 300w/16 Ohm? The only way the math adds up to me is if the 50w head is putting out a lot more than the nominal 50w, but is that normal even?

    Cheers

    My Marshall 4x12 is rated less than that (30 watt speakers) and A) hasn't burned up (yet) and B) is pretty darn loud with master at 30-40%

    It used to sound way quiet, tho, until I found a little check box in output "power amp boost" or something. Search forum because others have gone thru this low volume thing...

    here's someone's check list I found:
    After you have reintialized Global settings, first check volume levels using only Master Volume. If for some reason, you need more volume output out of your Speaker Output, first got to Output Menu, and boost the Monitor Output Volume.


    Next, If that still isn't enough, turn on the Power Amp Boost control in the Output Menu, and adjust.


    Make sure you have "Monitor Cab/Off" activated, if you are connecting directly to a traditional guitar cabinet.


    Another possibility, is to check any connected volume pedal (if applicable). You may need to recalibrate your volume pedal.

    Yep did all of those. Twice. Gonna check all the volume settings again once I get the cab situation straightened out. But I had them all maxed and was controlling the level via the master

    The cab is definitely blown, I just have to open it up and see how many of the drivers died (hopefully only one). We do rehearse loud I'll admit, but I had definite problems keeping up with the lead guitar that was on a 100w Marshall top with 1960 cab. Running at volume around the 4 mark. Pretty normal volume by our standards. Maybe it's all a coincidence and the cab was failing anyway (but that seems unlikely), so the only thing I can think of is either a fluke power spike or the output from the KPA. I play rythm Malcolm Young style so the sound is pretty clean with just a bit of break-up when I lean into it. I understand that the "percussive" nature of the clean sounds put even more strain on the cab.

    The math adds up, I have four 60w drivers (ie 240w) in my cab and if the KPA output was close to 300w I was definitely overloading the cab. I guess I need to get me either 4*75w (ie 300w) or even greater. I know that for tube amps the recommendation is to have 25-50% margin to the nominal output of the amp, but I don't have a clue if the same goes for a transistor amp. In which case I need to be around 400w instead (at 16ohm). Twice that for 8 ohm.

    So I guess I'm just looking for advice on good speakers since I won't be using V30's or Greenbacks and I don't want to lose the vintage sound.

    Have you tried adjusting the Amp volume in the stack section?

    I had some trial and errors with cab(s) volume as well. After owing a triple rec and an egnator vengeance, I've tried to chase the loud cab volume in the room to the same shaking levels as my guitarist Marshall jcm 2000 which is 100 watts. I blew up an old 2x12 because I got too excited with tone and tried to bump it.

    I also smoked a jbl 1x15+horn too. I don't use power amp boost anymore unless it's a last resort. I raise the master monitor output to almost full blast, and give the preset level and amp volume a boost along with a post stack eq boost

    Whenever I read these "not loud enough" posts, I gotta think that there is either a hardware problem or the profiles that are being used are very very scooped in the mids and just aren't cutting through.

    You could always get 4 EVM12Ls or the Eminence equivalent, they're not going to add any vintage grit but it'll take way more than a Kemper to blow them