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Need to tame the output of my Alembic F-1X

Discussion in 'Amps and Cabs [BG]' started by secretdonkey, Feb 9, 2005.


  1. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    After blaming it on other things, I've concluded that my Alembic F-1X preamp is capable of overloading the input of my Crest CA-9 power amp.

    With the preamp volume cranked up high, I can induce fierce, speaker-killing distortion on certain transient spikes. No clip light comes on when this happens (in fact, fortunately for my speakers, I've only done this with the amp's attenuators turned way down).

    For now, I'm simply keeping the F-1X's volume at about 5 and this makes a very practical solution. I can't imagine ever needing any more volume than what I get with the pre on five, and both channels of the CA-9 wide open. Never say never, though... and... the first time I accidentally bump that knob, or let someone else use the rig... I could wipe out both of my Accugroove cabs in an instant. That is no good, nosirree!

    BTW, putting my bass into the 6 db pad input of the Alembic will increase the usable volume level, but doesn't eliminate it the problem.

    What can I do to protect my speakers and milk all of the available potential from my rig?

    BTW, this is an older CA-9, and a tech from Crest told me that the input sensitivity isn't configurable on this model, as it is on newer ones.

    Any suggestions?
     
  2. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    I wouldnt turn the gain on the power amp up all the way... probably ever. It should take a stronger signal from the pre to drive the power amp to full output when the gain on the power amp is not all the way up.

    I usually turn my power amp gain between 9:00 and 12:00. Same volume settings on my pre will be sufficient to drive the power amp to full output with the power amp gain @ 9 but will clip the power amp very easily at the 12 gain setting. When I want my sound to get fuzzy I turn it up the pre real high and the power amp real low to avoid power amp clipping. Good luck donkey of secrecy! :D
     
  3. jvbjr

    jvbjr

    Jan 8, 2005
    Remove the knob, tape it into position, put some glue on it so it can no longer rotate, add a db pad on the output, don't bump the knob, don't lend it out....
     
  4. Ostinato

    Ostinato Guest

    Feb 7, 2005
    Toronto ON
    I've never dialed my volume past 11:30.
     
  5. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Ahhh... how do I do that?
     
  6. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    I think I'm overloading the input of the amp because I get this distortion regardless of the amp attenuator settings (I'm assuming - never tried it with attenuators turned up, for fear of hurting my speakers), no clip lights ever illuminate, and it isn't "fuzz" but total "crap-out" uberdistortion. :)
     
  7. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    One thought would be to get a compressor into the signal before it hits the power amp. Set it up in such a way that its not drastically altering your tone, just eliminating the transient peaks that are causing the input of the power amp to become overloaded/clipping.
     
  8. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Yeah, it occurred to me that the solution might be a limiter, compressor or some other box that could regulate signal level. I'd prefer something less invasive than a compressor, though. Any ideas on limiters that affect sonic quality of the sound as little as possible while offering total protection against these transient spikes?
     
  9. Lex P.

    Lex P. You've got it awful loud -Kathy P. Gold Supporting Member

    Mar 19, 2003
    MSP
    I too have an F1-X it is running into a PLX2402 bridged mono into a Bergie 2x10 and Bergie 1x15 cabs. The amps gain knobs are maxed out. The highest I've ever had to set my input gain is 5 and 3/4's. That is with a passive bass. It was REAL loud and sounded great. With an Aguilar 924 box between the bass and cab I place the input in the padded input with the 924's volume at max, bass slightly boosted and treble up just a hair. I run the gain at 5 and it is loud and warm sounding, no distortion whatsoever! I love the F1-X.
    Lex
     
  10. silky smoove

    silky smoove Supporting Member

    May 19, 2004
    Seattle, WA
    All of my compressor experience is with compressors that are less than transparent (BBE, DBX, Digitech, etc.), and then of course the one built into my Mesa/Boogie head. I'm sure there are some pretty transparent ones available though.
     
  11. thejohnkim

    thejohnkim

    Sep 30, 2003
    NYC
    i would definitely go with a nice limiter rather than a compressor, since it won't do anything to your sound until you hit the upper threshold and then it'll be like a brick wall, protecting your amp and speakers
     
  12. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    I know there's a school of thought that says that one should max the attenuators on the power amp and control volume from the preamp. That doesn't quite work for the Alembic, though. As we all know, all of the controls interact with one another, and at lower volume settings, the effect of the "bright" switch is simply too much. I'd like the tonal flexibility offered by having use of the full range of volume knob settings (at higher volumes, the effect of the "bright" switch is increasingly negated).

    With the Alembic's volume at noon, the CA-9's attenuators cranked all the way and both of my Whappo Jr. cabs hooked up, it's hard to imagine wanting more volume than that. There's still something perversely appealing about the ability to be *even louder*, even if I'll never actually need it. :cool:
     
  13. NJL

    NJL

    Apr 12, 2002
    San Antonio
    bump

    i'm curious
     
  14. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Specific recommendations on a limiter, anyone?
     
  15. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    If you have the gain knobs on the power amp all the way up and you are clipping it then you have reached the limit of the amps capability.
     
  16. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Nope, that ain't enough to flash any clip lights. :cool:
     
  17. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    well before i sold my alembic to dirk diggler i used it with a stewart 2.1. the highest i ever played it at was with the alembic's volume on 12 o'clock and the input gains on the stew on 12 o'clock. scary loud. i never experienced any distortion with the alembic (even when plugged into the effects returns of other amps) unless i cranked the volume knob past 3 o'clock or so. I occasionally ran a limiter in between the two for some speaker protection but that can compromise tone. i think you need to experiment more with the gain levels on your stuff or run some kind of pad in between the two.
     
  18. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
    Then either your clip lights arent working or something else is the problem.
     
  19. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    Not sure what you mean by "gain levels on your stuff." Someone earlier suggested a pad and I asked for an explanation. Can you elaborate?

    Thanks!
     
  20. secretdonkey

    secretdonkey

    Oct 9, 2002
    Austin, TX
    The clip lights work. As I speculated in my first post, I *believe* that the problem is that I'm overloading the input stage of the CA-9... an assessment that a number of tech types have agreed with. Explains why no clip lights and also (intuitively, at least) why the distortion doesn't sound like clipping/distortion I've heard in any other circumstance.

    :)