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Using power amps...

Discussion in 'Ask Mike Watt [Archived]' started by LaSalle Dioxide, Apr 13, 2003.


  1. Hi Watt --

    I'm the guy who razzed you in Salt Lake City about not answering my previous post on this site, you remember. I just want to know about using power amps. I see you use an Eden pre-amp into a power amp... I'm thinking of getting a Crown K1 or K2 power amp to help out my Gallien Krueger 700RB... I like the sound I get with just that head but I think it distorts abit at my preferred volume. I generally have the volume set just slightly past 12 o'clock. My GK has 350 watts... I'm thinking that I could use the GK as a preamp into a power amp and get most of the power I need from that. I don't know much about power amps, but the Crown sounded appealing because of its high "dampening factor", which I guess makes your sound punchier. I read that it has lots of a signal that sucks the speakers back in immediately after the speaker cones are pushed out. Any thoughts or suggestions regarding power amps?

    Oh, and like I said to you at the show in SLC, I loved watching you play. You play gracefully and I can't remember seeing anyone who seemed to having such a thoroughly good time. Anyway, I had a thoroughly good time.
     
  2. Subculture13

    Subculture13 Jamming Econo

    Apr 9, 2003
    Toronto, Ont. Canada
    Are you only using one cabinet with this setup? One thing you have to be careful about when using a powered head as a preamp ONLY is that certain brands and/or models (I would have to research the make you have to know if it's one of them or not) of amps still send a full signal to the speaker output even if there is no speaker attached. Some have a built in defeater that is active whenever a cable is inplace, meaning there is no "load" being sent until a cable is hooked up. If your amp is one that still sends a full powered signal then you may also have to look into setting up some sort of a dummy load resistor or "hotplate" to absorb the excess energy of the amp. If you do not do this you risk serious damage to your amp as it will overheat rather quickly. This is especially true in a tube amp, but can still occur in solid state as well.
     
  3. Hmm... I'm using one ampeg 8 by 10 cabinet, a Gallien Krueger 700 RB, and a SansAmp bass driver unit. As I said, I was hoping to use my GK as a preamp into, possibly, a Crown K series poweramp for more head room.
     
  4. Where are the settings on your amp? Level, Boost and Woofer?

    I think one of the problems that your experiencing has to do with the type of cabinet you're using. The Ampeg 810 is what's called a 'sealed' or non ported cabinet. The advantage of that is it pretty much sounds the same no matter how close or far you stand from it. The disadvantage is that it's not very efficient power-wise. A ported cabinet will reproduce the signal much more efficiently and has much better punch and low end. The disadvantage is that it will sound kind of thin when you're standing only a couple of feet away from it, but get about 10 or 20 feet out, and it'll sound great.

    Regardless, you shouldn't be getting distortion from the amplifier. The GK heads were designed to handle being driven hard. That being said, if you still want to use the GK as just a preamp, you'll need to use the send jack which is just after the EQ and just before the boost, or the DI out which is just after the boost in post mode.
     
  5. Level: five or six region

    Boost: five

    Woofer: six

    Like I said, I love my GK and the character of the sound I'm getting through my existing setup. I just feel that I'm pushing the limit of what my setup can deliver. Whenever I add a little more volume, gain, or woofer, I start to clip, etcetera. I don't need much, if any, more volume, but I'd like a slightly cleaner, punchier signal at the level I'm currently using. I'd also like to be able to have a loud, clear, punchy signal at a slightly higher volume if I felt a certain section of a song needed that.

    The idea of a super high dampening factor and more head room is what initially attracted me to Crown K series power amps. I didn't have a clue about dampening factor until I checked out their site. Apparently, the K series has a greater than 5000 dampening factor. Of course, I don't know what that really means, aside from the idea that it's a higher than usual signal designed to suck your speaker cones back in the moment they get pushed out. I understand that the higher the dampening factor, the greater the potential punch.

    I found out that my GK has around a 300 dampening factor.

    The idea of extra head room and mad punch sounds extremely attractive as I'm really into playing Big Black, Jesus Lizard - type influenced stuff. You know, a really aggressive, staccato, mean sounding style of playing.
     
  6. Do you have an active or passive bass? Is the -10dB pad in or out?
     
  7. I play a Travis Bean TB2000, which has passive pickups. I used to play a Music Man Stingray and the Bean sound seems much cleaner.

    I use a SansAmp Bass Driver to get a little more "teeth" and warmth in my sound.

    My -10dB pad is out.

    I keep most of my knobs set near 12:00 o'clock except for the low and high mids, which I set more close to 3:00 o'clock.
     
  8. Try it with the -10dB pad in, or reduce the output volume from the Sansamp then boost the woofer and tweeter volume on the 400RB to whatever you want. It's possible you're overdriving the preamp section a little.
     
  9. I gave that a try, pushed in the -10dB pad, turned the woofer and tweeter up to 3 o'clock, and I think some of the distortion did clear up and I'm still retaining all of the guts in my sound. That did help.

    Thanks.
     
  10. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    I recently found out that the speaker cable you use has more effect on the damping factor than the power amp. So don't get hung up on damping factor - just buy a thicker speaker cable. (See Bob Lee's posts in the amp forum for more clarification).

    Alex
     
  11. watt

    watt TalkBass Pro Supporting Member

    lasalle,

    sorry about not getting to your post but getting ready for tour and then tour itself can be so intense on me. no offense intended. sorry.

    on idea might be to run two cabinets, maybe a small 2x10 w/the gk on top of the svt cab (maybe you could put your amps on the ground, next to the cabs) and then have the power amp run the svt cab.

    the power amp I'm using is an eden wt-1000 and it has two 500 watt amps - I have each powering an 4x10 eden cab.

    as for dampening and all that - I use big speaker cables (I mean thick). trust your ears though - try stuff out before buying and not rely on hype.





    on bass, watt