Kustom deep end 50watt into ampeg 810

Discussion in 'Amps and Cabs [BG]' started by Arenegadeoffunk, Jan 23, 2021.

  1. Arenegadeoffunk


    Dec 17, 2020
    Hey guys, I'm a guitarist who really enjoys bass equipment and also discussing equip. and reading all you guys have to say basically... anyway I have a Kustom deep end 50watt (de50) I ripped out of a combo and it's a bonafide tone machine(I imagine it sounds alot like an ampeg svt since the same guy designed this line of kustom, probably to save their amps since, let's be honest they're not great) I recently got an ampeg 810 svt cab that is also quite special, really my first cab that adds to the tone real nice. Btw I play through an epiphone DC pro and i like my OCD ge alot. I'm interested in anything you guys have to say in general but here's my real question.. my de50 speaker out is 8ohms, my svt cab is 4ohms. I couldn't resist and I finally rolled the dice and it sounds great, but the amp got warm pretty quick and I dont want to damage it, it's only got a tube preamp, the rest is solid state so I'm sure it's tough as nails, and you all know there's conflicting opinions on ohm matching, especially when solid states involved.. what should I do??
  2. MarkA

    MarkA In the doghouse. Supporting Member

    Sep 26, 2008
    Have a look at page 6 of this manual: Kustom DE50 Owner's Manual (Page 6 of 12) | ManualsLib

    Minimum load for this amp is 8 Ohms (when in the combo, per the manual, the internal speaker is disconnected when you hook up an external cab -- I realize that yours is pulled).

    Running the amp at 4 Ohms is running it out of spec. You might get away with it for a little while or a long while, but "got warm pretty quick" is not a good sign. I would stop using it at 4 Ohms. If your 810 is set up as two, 8 Ohm 410s (some are) you could run one of them.

    BTW, you don't need to "match" impedance (Ohms) with a solid-state power section (like you want to with tubes). The rating given for SS heads is a minimum impedance -- for this one, acceptable loads are 8 Ohms or above.
    Arenegadeoffunk and el murdoque like this.
  3. el murdoque

    el murdoque

    Mar 10, 2013
    This is news to me. To my knowledge, the SVT was designed by two guys (Bill Hughes & Roger Cox), who left Ampeg, but went more or less directly to Fender (maybe someone with real knowledge might chime in?).

    I don't know about conflicting opinions about ohm matching with solid state amps, not at all.
    The last time I checked, all the experts and experienced players here on talkbass agreed to the following:
    When the back of your (SS) amp has only one outlet, which is labeled 'Min X Ohm' it means that the amp will work with any speaker configuration where the total load is equal to or bigger than X Ohm.

    Running less than that is bad.
    The worst case scenario would be that you blow your output transformer which in turn, could hiss out a few volts of death rattle that kill the attached speaker.
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  4. Arenegadeoffunk


    Dec 17, 2020
    Unfortunately I just have the mono, I'm thinking of looking for the speaker out to a stereo svt cab and rewiring it since it would solve alot of problems, it's a real shame bc I knew it would sound great with my de50 and I'm basically just teasing myself, the only amp I have with a speaker out at low enough ohms is my dual rec, which also sounds killer but I like that amp for my highs
  5. Arenegadeoffunk


    Dec 17, 2020
    I'm sure I heard it in a video or somewhere digging around and it makes sense looking at the design, but anyway about the ohms as I understand guitarists are usually less learned on ohms because I read ALOT of conflicting material on ohms, I like to think I know what's right, but alot of guitarists like to get away with things and say things I'm not sure I agree with (because I'm no electrical engineer) like if the transformer is beefy enough it can take it or halving the ohms isn't a problem.. part of why I like this place is not only I play with more bass equipment but you bass guys seem to be a little more learned, especially on equipment.. and we all know some guitarists have big egos and might add to a thread just bc they disagree or "me and my buddy did it this way and nothing went wrong"
  6. el murdoque

    el murdoque

    Mar 10, 2013
    Understandable. In bass playing, solid state amp heads are much more common than with guitars. I mean, that's quite reasonable since most bassists play clean and need a few hundred watts at their disposal whereas guitar players get along with a tenth of that - and a proper bass tube amp is a 80 pound monster that costs a fortune.

    Tube amps and SS amps are very different in the regard of the attached load.
    When you fire up the amp with no speaker attached, the load is unlimited ohms.
    A SS amp will be fine with that and (speaking in layman's terms) produce no watts.
    A tube amp will not at all be fine with that and produce voltage that has nowhere to go, so it blows the output transformer.
    If you attach, let's say 4 8 Ohm cabinets by daisychaining them to the outlet, the combined load the amp will see is 2 Ohm. A solid state amp (again, layman's terms) will feel not enough resistance pushing back and put out more than it safely can, so it might run fine for a while, but eventually the weakest link will give. A well protected amp (good engineering) will shut down to cool off and be functional after a bit. A not so well protected amp (budget engineering) will run hot and melt.
    Do the same thing with a tube amp and it's probably not too bad. A friend of mine did it with his guitar amp all the time (4 ohm cabinet on an 8 ohm outlet) and the amp took it.
    But to be on the safe side of things, the rule is to attach the exact load to a tube amp and not undercut the minimum load for a SS amp.

    The problem described in Post#2 is that the Kustom amp seems to have a 8 Ohms minimum. For a combo, it would be more common that the minimum load printed on the back refers to the minimum load of the ext speaker while the combo speaker is still active. So a combo that has an 8 Ohms internal speaker and a min load of 8 Ohms specified for the ext speaker usually has a real min load of 4 Ohms - because when you join the internal 8 Ohms cab with the ext 8 Ohms cab, you'll get 4 Ohms. In your case, however, @MarkA has deduced from the facts that a) 8 Ohms is the specified minimum and b) when connecting an ext speaker, the internal speaker is shut off, that the min load of the amp is indeed 8 Ohms instead of the much more common 4 Ohms most bass amps have.
    Arenegadeoffunk likes this.