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Slaving questions

Discussion in 'Amps and Cabs [BG]' started by Southpaw5, Oct 22, 2010.


  1. Southpaw5

    Southpaw5

    Jul 18, 2009
    Boston
    Hi Folks,

    I've been reading in bits and pieces about slaving but I'm just not getting the full picture. It seems like this should be in the amps FAQ section but I couldn't find anything. It seems peoople like to use it to get the same nice tones they get out of vintage gear(like an ampegB25B) that is sent(or received?) to(from?) a more powerful amplifier, but I don't really understand the process. Please... educate me.

    Thanks in advance!
     
  2. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Slaving used to be common, but today the better option with a low powered vintage amp is to just mic it into the PA. Much of vintage tone comes from the speaker, and a mic is the only way to capture that.
     
  3. Soreinsun

    Soreinsun

    Oct 22, 2010
    I too am very interested in learning about slaving. St. Victor Wooten runs two 1000 watt Hartke's these days, and as near as I can tell the two are linked together. I don't know if slaving is the deal there, but that's when I had the thought to try it.

    I thought I might try running two BX500's using the direct out from one to roll into the other. I'm not sure what that would buy me but more acoustic output (and the obvious awesome feeling of running two stacks).
     
  4. Southpaw5

    Southpaw5

    Jul 18, 2009
    Boston
    I'd mostly be using this at may practice space so miking won't be done. regardless of how common it is these days, I'd like to learn more about it.

    Thanks
     
  5. One thing I wonder about is this - does anyone with a smaller wattage amp (Like a B-15) who needs more power, ever just "self-mike" on the stage?

    So have your little amp, mic, little mixer, and a powered mackie speaker?
     
  6. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Slaving can only be done if both amps have a preamp OUTput, and poweramp INput. You wouldn't use the XLR out, as that's intended to be used in a mixing board, (line level) If any of the 2 amps are tube amps, they MUST be connected to a load, (speakers). The whole idea is to increase power to achieve more volume, but without sufficient speakers, it's pointless.One amp acts as the master, you plug your bass into it and control the tone. from that amps preamp OUT, you connect to the slave's poweramp IN.
     
  7. Dude, slavery is wrong.



    ;)
     
  8. Soreinsun

    Soreinsun

    Oct 22, 2010
    Sartori, I will whip and beat my bass amplifiers until they dun picked all God's cotton...
    :-D lol

    But in all seriousness... Rickenboogie... I THINK I understand what you are saying... in other words the signal that goes into the SECOND power amp is the ALREADY boosted power from the preamp. INTERESTING... so you're just using the amplification properties of a higher powered amplifier with the "tone" properties of the first amplifier.

    In a nutshell if you wanted to be more efficient with this, someone could just purchase a (power amplifier) and use the (preamp out of their first amplifier) to run into the (power amp). Well that's not very exciting at all. Slaving sounded way sexier when I assumed somehow you can increase actual volume by COMBINING two amps.

    The whole idea behind my XLR direct out idea was to run a line level INTO the next amp, therefor I wouldn't end up destroying that amplifier with the boosted sound from the first and be able to set new tone controls and run a 2 or 4 ohm 500 watt secondary stack at the same time. Is there any reason why this wouldn't be a good idea? Aside from the obvious cost prohibition...
     
  9. Oren Hudson

    Oren Hudson

    Dec 25, 2007
    Gastonia, NC
    Southpaw5 - You mention a B25B Ampeg head. I have a '72 matching head and cab with the optional Altec 421A speakers. A very very desirable tone with nominal power. I bought a 70s Acoustic Control Corporation slave amp that runs about 125 watts RMS. I then paired it up with the B25B rig and used an older 1-15 semi folded horn Dean Markley cab to complete the deal. Exactly what I was looking for. Enough boost to put some pretty thumpin' bass out in a fairly loud band scenario. The slave amp doesn't flavor the B25B head, just adds power. Just remember that with many rigs, particularly the older ones, you have to use another cab to properly and safely use a slave amp with another rig. :cool:
     
  10. Slaving an amp, to my understanding, doesn't disable to the power amp of the first amplifier.

    This is very important to remember with tube amps.

    For an example, say you have two SVT's. You would run each of them to a cab (or, more awesome, two cabs each), but if you slaved them together, you would control all the tone and such from the first one. Both would still be connected to the speakers, but you could adjust any EQ from one.
     
  11. Soreinsun

    Soreinsun

    Oct 22, 2010
    So in effect you are using two "separate" amplifiers at once in the sense that they are producing their own power and each have their own loads. You DON'T run the power of one amp into the other or some such nonsense and get a billion watts. The whole purpose then is to maintain all tone controls from one preamp AND maintain that sound through the slaved power amp?

    INTERESTING! So in effect, if I could send out a preamp mixed signal from my Direct Out (granted it would be line level, but that's easy to fix) into another amplifier's 'preamp' and leave that preamp alone... Slavery: you're doing it right?
     
  12. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Again, as far as I know, (first flaw) you DO NOT want to use the DI for any of this. The DI has one purpose, to send a line level signal to a mixing board for a PA or recording console. Sending a line level signal into a preamp is bad. Very bad.
     
  13. Soreinsun

    Soreinsun

    Oct 22, 2010
    Rickenboogie... I must warn I'm a few beers deep tonight as I write this so if I come off a little belligerent, forgive me!

    A line level is far less potent than an instrument level. Especially for bass. Basses for some reason send out really hot signals. Hence the need for a line level. I fail to see what would be so bad about my idea of running the direct out of one amp into a preamp of another. If you could plainly tell me, however, I would be much obliged. The line level is FAR less potent than an instrument signal.

    Please correct me if I'm wrong!
     
  14. Bassdirty

    Bassdirty

    Jul 23, 2010
    CT

    +1


    ?

    .
     
  15. Soreinsun

    Soreinsun

    Oct 22, 2010
    Yessir.
     
  16. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    That's why I began that post with these ^ words. Because, obviously, I'm confusing this thread with some other unrelated thought process of unknown origin- hence, the flaw being my thinking. Continue on, I'll be in the other room.
     
  17. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Line level runs about ten times the voltage as instrument level, which is at least ten times the voltage as microphone (XLR send) level.
    +1, and if those speakers aren't identical to those of the primary amp then the tone from them won't be either.
     
  18. RickenBoogie

    RickenBoogie

    Jul 22, 2007
    Dallas, TX
    Ah, thanks Bill. You are the man.
     
  19. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    As best I can recall it was primarily Sunn that was into the master/slave concept. They had an amp as the master, and the same amp's power section sans pre-amp as a slave. Each drove an identical cab. That was in the late 60s/early 70s when good PA didn't exist and there was justification to using a pair of 2x15s. Good PA came along and the master/slave thing went away.
     
  20. Soreinsun

    Soreinsun

    Oct 22, 2010
    Did I mention that my Direct out IS an XLR send?
    That means that it's NOT line after all, I guess.
    An engineer (notorious for being wrong) once told me that the XLR send on my amp was sending at low level... (maybe he said "low z"... whatever that means...)
     

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