Matchless DC 30 / AC 30 style Amps ....... Kemper Support advise that they [ probably ] *cannot* be Direct Profiled ...... !!!

  • Hi all


    Firstly, major thanks and kudos to Kemper Support - over the last 2 weeks I and they have been emailing each other re: the "bug" of not being able to do a Direct 3.0.1 profile of my Matchless / Ceriatone DC30 amp.


    - numerous information emails were exchanged
    - they requested and I sent them my [bad] 3.0.1 Direct Profiles and my [good] 3.0.1 Studio Profiles
    - Kemper Support provided them all to their tech's to examine.


    Last night I received the following email from Kemper Support


    " I talked to our developers about this. It seems that your amp is one of the few that can not be profiled using the direct amp profiling method. AC 30s are quite difficult to profile in general and in the case of your clone it seems to be impossible. This could be because of the way its internal circuits work. Please use the studio profile of your amp. I am very sorry i cannot give you any better answer. "


    All I can think of is that DC 30 / AC 30 style amps have 2 key features in their designs that *may* be causing this issue:-


    - Cathode Bias
    - No Negative Feedback in the Power Amp stage


    Oh well ...... maybe future FW updates can/will address this.

    Maybe some other AC30-style amp owners will try a 3.0.1 Direct Profile and report back :)


    It did surprise and intrigue at the time that the batch of 49 new Merged 3.0.1 profiles released with FW 3.0 did not include an AC 30


    Ben

  • don't all amps have this, if turned up?


    Actually no. Of course, when really cranked you can distort a 50 W poweramp that's powered with 2 6L6's or EL 34's, but this is not how distortion usually is generated. Perhaps CK can chime in on this topic as well.

  • So when people talk about "driving the power tubes hard", it's not really distortion that is happening, typically?


    (would love to understand this better :-))


    I think often there is a misconception about 'driving the power tubes hard'.
    When I still had my Marshall 6100 I could use it in 50W (2xEL34) or 100W (4xEL34) mode.
    Cranking this beast in the powersection even in 50W mode was so deafening loud nobody with a sane mind would do this. I could not get real poweramp distortion from it, but in 100W mode its bass response was more stable and stiff (in lack for a better word).
    An AC 15 or 30 which is, to my understanding) running in class A will contribute a good portion of poweramp distortion when cranked (still VERY loud) ;)


  • I think often there is a misconception about 'driving the power tubes hard'.
    When I still had my Marshall 6100 I could use it in 50W (2xEL34) or 100W (4xEL34) mode.
    Cranking this beast in the powersection even in 50W mode was so deafening loud nobody with a sane mind would do this. I could not get real poweramp distortion from it, but in 100W mode its bass response was more stable and stiff (in lack for a better word).
    An AC 15 or 30 which is, to my understanding) running in class A will contribute a good portion of poweramp distortion when cranked (still VERY loud) ;)


    Yeah, I get the loudness issue for higher-wattage amps :)


    But so many people talk about getting the power amp tubes cookin' in order to get the best tone, hence they go for lower wattage amps, for instance in the studio. But this seems to be a separate issue? Or is the profiler not able to profile ANY amp which is turned up to that point? (and I know that maybe only kemper can answer :-))

  • I have successfully direct profiled a Vox AC4TV at full volume which is all about power amp distortion, so I don't think that's the problem with AC30.


    On the other hand, I was not able to profile GT Soul-a-Single, which is single ended class A. Go figure.

  • well bearing in mind a lot of the old good sounding vox AC30's don't have a speaker out jack anyway.. so you cant do a DI of this amp even if you wanted too. - same with some of the older h/w fenders that are solderd speaker connecters direct to board.


    Some things we just cant ever have...

  • The OP was talking a clone tho :)


    FWIW ..... as Gianfranco notes, my Ceriatone DZ30 is a direct clone/copy of the Matchless DC30 .....which in turn is [ essentially ] a very souped-up AC 30 ...... imagine an AC 30 that sounds like a classic AC30 but only more and better :)


    The AC4TV has 1 x 12AX7 and 1 x EL84 ........ AC 30 / DZ 30 / DC 30 has 3 x 12AX7 + 1 x EF86 + 4 x EL84.


    AC4TV is a great sounding amp, but electrically its a lot different to a full-blown AC30 style amp ...... BUT ...... the fact that you were able to DI profile it is VERY promising :)


    Also ..... the issue I had was on both the speaker-out-DI [ 3.0.1 ] -and- the pre-amp-out !?!?!?


    I guess its *possible* that the Kemper just does not like AC 30 style amp DI feeds ?!?!? .......


    Surely it is only a matter of time before the FW is "fixed" (?) and/or someone else does and posts a succesfull AC30 / DC30 set of Direct DI profiles :)


    I mean seriously, can you imagine have a Kemper with Merged / Direct profiles of holy grail Marshalls & Fenders but no Vox AC 30's ........ that's 1/3rd of the holy trinity of amps missing !!!!:):):):)


    Ben

  • AC4TV is a great sounding amp, but electrically its a lot different to a full-blown AC30 style amp


    Sorry, I was not clear. I didn't mean to imply that AC4TV would be similar to AC30. My point was that you can definitely direct profile amps with a lot of power amp distortion.


    Try my 'axAC4 95' as an example of that.