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QSC GX3 power amp comparable to SVT output?

Discussion in 'Amps and Cabs [BG]' started by bthiemann80, Sep 15, 2008.


  1. I'm looking to build a portable rig in lieu of my SVT. The SVT has 300 watts RMS of output and I know that technically a watt is a watt is a watt etc. However, I also know that there is percieved volume that seems to differ from the technical side in which a lot of times tube wattage sounds louder than solid state.

    Anywho, i'm thinking a good comparable solid state power amp to rival the 300 watt SVT would be the QSC GX3. I would be running it at 4 ohms, which would be 425 watts per side/cabinet. I'd be running 2 Avatar b410's or one b210 or one b210 and one b410.

    My only concern is that the GX3 would not be able to give me the kind of power/volume I'm used to with the SVT. Or that the 425 watts of output per side (or speaker cabinet) from the GX3 wouldnt be enough to push the 1000 watt b410's, thus frying them. Has anyone out there had any experience in this kind of situation
     
  2. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Watts is watts. The only reason it sounds louder is because tubes distort in a pleasing way that doesn't always sound distorted.
     
  3. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    True. The result is that if you push both 300-watt amps to, say, 400 watts, the SS amp will either have a lot of mostly odd-order distortion or its clip limiter (if it has one) will cut back the gain, while the tube amp will distort much more gently.
     
  4. Thats pretty much what I suspected. The thing is, I've never had the need to push my SVT to the point of distortion. I've never really had to have the volume past 3:30/4:00 o'clock and gain never really set past noon. At that volume the SVT doesnt sound distorted to me at all. Now it is entirely possible that the SVT is in fact distorting at the higher volumes but due to the all tube nature of the amp it sounds fine. Whereas the GX3 being pushed to the same or similar output may exhibit audible distortion. I guess I would have to A/B both the SVT and GX3 side by side with the same speaker setup to see if they would possess the same output. Thanks for all your input guys!
     
  5. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Could be. Even substantial "soft" distortion may not sound like distortion; it might actually be very pleasant sounding.
     
  6. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I missed this part last night...you do not blow speakers by underpowering them. You blow them by trying to force them past the limits of what they can take. Hard to do that if you're underpowering them. I turned my 25w B-15 up past clipping into a 300 or 400w speaker many times and it's still going strong.
     
  7. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    I missed that part, too.
    If lower power somehow fried loudspeakers, we could never turn our rigs off, or even stop playing. ;)
     
  8. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    LOL! I could picture that..."Man, I really gotta go to the bathroom, but if I quit playing, my rig'll blow! What do I do???" ;)
     
  9. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Or "Jimmy! Put that damn bass away and come to bed already!"

    "I can't, honey! It'll fry my speakers!"
     
  10. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    There is a school of thought that says that if you drive an adequately-rated speaker (let's say 500 watts) with an overdriven, clipping output from a lower-powered solid state amp (let's say 300 watts), that the nasty transients from the amp will cause over-excursion of the speaker and will indeed cause damage.

    Obviously, overdriving a solid state amp is not good, whether it causes speaker damage or not. The solution: more power. If your speakers can't handle the power, you will hear it and (hopefully) turn down. Then you will go buy more and/or better speakers.

    To the OP's question: 425 QSC solid state watts per side into a pair of 4-ohm cabinets will certainly match or exceed the loudness of the SVT's 300 tube watts. However, if you're only driving one side (425 watts) into a single cabinet, you may indeed get less loudness than the SVT. Can your QSC be bridged to operate as a mono amp, and will it safely drive a 4 ohm load when bridged? If so, you will be able to throw more power to that single cabinet - maybe 1,000 watts or so, if it is spec'd like my Crown amp.

    And of course no one really uses all that power - it's just there for "headroom"!
     
  11. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    That's a school of not enough thought. ;) "Nasty transients" don't cause overexcursion.

    Lower frequencies cause longer cone excursion, 4× for every drop of an octave. Below the tuning frequency of the cabinet, it'll increase even more, to where even moderate power levels at a low enough frequency can cause the cone to bottom out.

    When an amp clips, it produces power in excess of its rating. That can be dangerous, just as too much "clean" power can be.
     
  12. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    If those transients cause a speaker to blow, then they're coming in at higher wattages than what the speaker(s) can take. Clipping in and of itself will not cause a speaker to blow. Take a SS head and turn the gain way past clipping but keep the master low. It's not going to blow the speaker.
     
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  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    No, not true.
     
  15. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    That's the truth to that school of thought. Sorry about the "nasty transients" part. Clipping is the observed symptom, overpowering is the root cause.

    You're right, of course. OP is asking about using a power amp - just volume, not gain & master. And in that case clipping at high volume levels = overpower, which my most-children-left-behind school incorrectly attributed to transients.
     
  16. gerryjazzman

    gerryjazzman Supporting Member

    Dec 31, 2006
    New Jersey
    Basically you can get 500 watts with only one channel driven because the power supply can actually supply a bit more voltage with only one of the channels loading it, so there is a bit more output voltage swing into the load resulting in a little more power. This is essentially the same phenomenon as "sag" that g****r players sometimes like in their tube amps.

    If there is any question about having enough power from one channel, for 100 bucks more there is the GX5 : 700 watts/ channel into 4 ohms, 850 watts / 4 ohms with one channel driven.
     
  17. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    The GX series amps are not made to be bridged. They're targeted toward a really entry-level segment of the audio market (and it might be better if they do not bridge their amps). ;)
     
  18. I am aware of the GX5. But I would like to save that extra money that would be the difference between GX5 and GX3 for some other gear. I'm not concerned with having an excess of power, just enough to rival the SVT output.
     
  19. Where do you guys see the PLX series? The -04s are SO light. However, I wouldn't want to be accused of being "entry level". ;)
     
  20. rok51

    rok51

    Sep 2, 2002
    Crawfordville, FL
    I cannot say enough good things about my PLX2 1804. IMHO, it's the perfect output for so many of my needs...I'd like to replace all of my lead sleds with them, but it will have to wait awhile...Meanwhile, paired with my F-1X, it powers all four of my GS112s with considerable authority...does real nice with a pair, too...or even one, for that matter.

    Kim
     

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