Marshall 4x12 cab and KPA PowerRack

  • I totally understand your concerns, I did have them myself some time back. A few months ago I moved away for music school, bringing with me a shitload of gear including a Marshall stack and the Kemper Powerhead.


    I have played a lot of guitar since then; live gigs, but mostly in a steamy and sweaty practice room with two or three other equally sweaty guys. Long story short: after fighting it way too long all the tube amps have to go, because the Kemper is simply the superior piece of kit in every way!


    I mostly use it with custom Zilla cabs strategically ordered to maximise volume and headroom (8 ohm and 100db speakers), and when I try to turn the volume past five I start to get complaints and have to turn down again... Haha! If you get the cab rewired and it still won't play loud enough, you should borrow another cab with max 8 ohm and 100db speakers like V30s or G12H30s. I did actually notice a larger difference between 97/100db speakers than 8/16 ohm.


    Just my two cents :)

  • I run a 412 EVH Cabinet (16 ohms) and a Marshall with two V30's and two EVH GB's (all 16 ohm) running the two cabs in parallel to get me 8 ohms.
    This is LOUD and comparable to my 50 watt Marshalls or EVH 5150iii 50 watt head.

  • Cheers, this all sounds great, thanks for your input, I dunno who else reads this stuff but as a Pro working musician I have gone beyond the patience threshold of changing my entire rig or buying even more speakers that are just thrown around in order to fix a problem that shouldn't exist.


    One reaches a point in gigging guitar life when it no longer is a n option to find oneself carrying more gear than necessary or throwing bad money after good in order to chase a problem...


    If anyone out there can tell me if my old Marshall cab which is 4 x 25w Celestion 16 ohm
    greenback speakers when reconfigured to 4 ohms and whether the result would be access to more volume SAFELY from the KEMPER and not suffer loss of tone?


    I would be grateful....


    Much love to my fellow KEMPERNISTAS :thumbup:

  • I run a 412 EVH Cabinet (16 ohms) and a Marshall with two V30's and two EVH GB's (all 16 ohm) running the two cabs in parallel to get me 8 ohms.
    This is LOUD and comparable to my 50 watt Marshalls or EVH 5150iii 50 watt head.

    My Marshall cab was wired in stereo until buying the Kemper: 4x16 ohm speakers split in pairs, which I believe would have been 2 lots of 8 ohms.


    I rewired the cab back to mono 16 ohm for the PowerRack speaker output... maybe I should have left it?


    SO, if you run two speakers how do you configure the single speaker output from Kemper to connect two speakers?

  • I run basically the same step up - high gain profile on Powerhead into a 16 ohm vintage Marshall cab (with mix of Black and Creamback's, approx. 120 watts) and it is loud as f*@k, at least inside... as I recall I did need to go thru all those settings / menus a couple times to sort out the outputs... check em again? Probably something simple. I'll check my parameters tonight and post back.


    PS: outdoors you might have to dime it...


    Master: 5.0
    Monitor volume: -13.7 db
    Power amp boost: 12 db


    My settings at rehearsal, usually don't have to change at gig (stage volume determined by a fairly loud drummer). We play screechy punk horror metal, relying heavily on feedback and jumping around.


    Rehearsal into 2 x 12 (half a shitty peavey 4 x 12 cab I wired to stereo in the 90's - modern 75 watt Celestions, can't remember ohmage...),


    Gigs, into a vintage Marshall 4 x 12 similar yours (30 watts black/creambacks, 16ohm). (I replaced the back of the cab with a nice piece of birch, that can help tone).


    I also have custom 2x12 with reissue Greenbacks (total, 16 ohm) that's plenty loud, as well.


    Plenty of headroom for most situations with any of the above, tho outdoors seems like the sound can disappear but I'm sure that's with any set-up. I guess the only difference is the back/cream backs speakers vs the greenbacks.. altho my 2x12 tears it up.... can you borrow another cab just to make sure it's not your settings?

  • If your 4x12" has four 16 ohm speakers you could easily rewire it if the cables have lugs (not requiring soldering). Rewiring everything to parallel (two and two speakers wired in parallel with each other, and then the pairs wired in parallel with each other.) will result in a 4 ohm load, and if you take a picture of the original wiring it is very easy to reverse. Unfortunately you cannot achieve an 8 ohm load with four 16 ohm speakers, but 4 ohm is safe as confirmed by Kemper.


    If you for some reason don't want to do it, I would strongly recommend you to try another cabinet. 97db speakers and 16 ohm will lower the perceived volume/power to 150w compared to 300w with 100db speakers and 16 ohm. I sincerely hope you will find a solution to this issue! It isn't just a pain when gear doesn't work as it should or expected, but you also deserve to experience what it is like to gig a Kemper without worries! Because it is simply a wonderful thing :)

  • If your 4x12" has four 16 ohm speakers you could easily rewire it if the cables have lugs (not requiring soldering). Rewiring everything to parallel (two and two speakers wired in parallel with each other, and then the pairs wired in parallel with each other.) will result in a 4 ohm load, and if you take a picture of the original wiring it is very easy to reverse. Unfortunately you cannot achieve an 8 ohm load with four 16 ohm speakers, but 4 ohm is safe as confirmed by Kemper.


    If you for some reason don't want to do it, I would strongly recommend you to try another cabinet. 97db speakers and 16 ohm will lower the perceived volume/power to 150w compared to 300w with 100db speakers and 16 ohm. I sincerely hope you will find a solution to this issue! It isn't just a pain when gear doesn't work as it should or expected, but you also deserve to experience what it is like to gig a Kemper without worries! Because it is simply a wonderful thing :)

    Yes this is the best solution. Couldn't be explained better.

  • Regarding settings... make sure this little box is checked. If not the "cab" part of profile is going to your monitor output and your sound will be completely jacked up. When I first tried a KPA out the Guitar Center guys didn't know this so it sounded like ass. It's counter intuitive to have to click a box on to turn a feature off.... Please double check this and the "Monitor Output" volume before you rewire a cab - I had to go thru the same thing to get my stage volume.


    FYI Kemper manual warns against loads of less than 8 ohms.
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  • I run my powerhead into a Splawn 4x12 with Creambacks and its super loud. Make sure your Monitor volume is up and linked to your Master Volume. Also maybe your profile amp volumes are down? I have no problem keeping up with my bandmates 100 watt JCM800

  • Regarding settings... make sure this little box is checked. If not the "cab" part of profile is going to your monitor output and your sound will be completely jacked up. When I first tried a KPA out the Guitar Center guys didn't know this so it sounded like ass. It's counter intuitive to have to click a box on to turn a feature off.... Please double check this and the "Monitor Output" volume before you rewire a cab - I had to go thru the same thing to get my stage volume.


    FYI Kemper manual warns against loads of less than 8 ohms.

    Thanks for taking the time to explain and photograph your unit.
    I have checked the monitor cab off thanks... I am still perplexed as to why the ADA & Rocktron Poweramp combination is way louder than the Kemper.... both poweramp are rated at 150w into 16 ohms and 300w into 8 ohms. I use the same cab and the same settings of a medium output on the individual master programs but the Rocktron is blowing the Kemper on almost full out of the water whilst only on about 4 !!!

  • Geez - I wish I could be more helpful... it doesn't add up, hardware wise, which still leads me to believe there is a setting that needs adjustment somewhere... you got the "monitor output" volume up? I thinks its on the next (or previous) page of the dialog screen I posted.

  • It is really nice of you to be involved mate...Thanks.


    I have linked the monitor out to the master so I can turn up monitor output from the master volume pot which is the best solution for live.


    I have tried to check that the monitor is indeed linked properly to the master volume and it looks to be fine...


    A small but relevant problem is that my cab is in storage until we next play a show, so I cannot fully check and adjust until the next gig. I may however rent a rehearsal studio room and try it through a hire cab. Saying that, you can never fully test without a full band being present....


    Kind regards to all Kemperites :-)

  • Hi mate, it is not resolved as such, simply because my cabs are in storage, I am out gigging this weekend and will try some adjustments and see if I can improve things. It is awkward not having my cabs to hand but even then it's impossible to get a true picture until the whole band are playing....


    I will let you know if things are improved over the next few shows - best wishes :-)

  • Dude this isn't right. I have done the opposite and rewired my 4 x12 from 4 to 16 Ohms (more amps have 16ohm output than 4). I therefore run mine live into 16 ohms ( Celestion G12's and V30's) and I never go above quarter volume...and its loud.


    I also had a volume issue ( no volume in first part of volume travel, then lower/inconsistant volume).


    It turned out to be a linked volume issue ( with monitor), so I would suggest unlinking all volumes first before you re-wire anything. Otehrwise raise a support ticket.


    The power amp is loud and should be as loud if not louder than your Rocktron...I'm convinced its a settin but its irritating when you can't find it!