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Cab selection question ? (wattage)

Discussion in 'Amps and Cabs [BG]' started by Gman, Nov 17, 2001.


  1. Gman

    Gman

    Jan 4, 2000
    Indianapolis, IN
    I just bought my SVT-3 Pro. I have some questions about what cab(s) I should have.

    The SVT3-Pro is rated at 450 watts, at 4 ohms. I wanted to get a SVT-15E, and a SVT-210E, both are 8 ohm. These cabs are both rated 200W RMS, 400W program. Believe it or not, GC didn't have these cabs. Special order. So I ended up leaving there with a STV-410HE. This cab is rated 400W RMS, 800 Program, 8 ohm. My plan was to get the 1-15 to go with it later.

    I used it tonight, and it sounded great, compared to the B-100R I'm used to, but I just don't think the cab is being driven to it's best potential due to the high wattage rating. So I'm thinking about taking the 4x10 back and having them order the 2-10 and 1-15.

    Is my thinking way off, or am I on the right track as far as matching power ratings. I understand the impedence, just not sure about matching power ratings.

    Thanks in advance,
    Dave
     
  2. Gman

    Gman

    Jan 4, 2000
    Indianapolis, IN
    bump
     
  3. The amount of power a cab can handle has no bearing on how the cabinet sounds. As long as the cab is rated to take the maximum clean power that your amp can deliver you should be fine. There's not really any such thing as underpowering a cab and by the numbers you're quoting it's about exactly right. I'd keep the 410, unless you're concerned about portability. It should sound deluxe with the 15!
     
  4. cassanova

    cassanova

    Sep 4, 2000
    Florida
    you can underpower a cab, its when you dont have enough power to properly push the cab, The end result is your amp/head clipping.

    ex:120 watt amp run thru a 600 watt cab.

    major clipping at high sound levels, due to underpowering the cabinet.
     
  5. Gman

    Gman

    Jan 4, 2000
    Indianapolis, IN
    Keep 'em comin' guys. If we get enough replies, eventually we'll get a majority on one side or another. :D

    Thanks,
    Dave
     
  6. CrawlingEye

    CrawlingEye Member

    Mar 20, 2001
    Easton, Pennsylvania
    There's no cab that you *should* use with it.

    That's all pure prefrence. :)
     
  7. I bet it would sound pretty good with the 2x10 and the 15. If it were me I would probably go with another 4x10. Try to find them somwhere and try them out w/your head and bass.

    jtbp
     
  8. Gman

    Gman

    Jan 4, 2000
    Indianapolis, IN
    I know it's mine, and I can do whatever I want with it, but what I'm looking for is technical advice on OPTIMIZING my rig. I want the cabs that will make the most of my head and vice versa.

    bgavin ? Joris ?

    Thanks,
    Dave
     
  9. RebelX

    RebelX Guest

    Oct 27, 2001
    Merrimack, NH
    I agree with Cassanova on this one. The underpowering condition that causes damage is when you have to continually push your amp to keep up volume wise. If you start clipping your amp trying to push your cab, then you run into problems.

    With that said, if you don't have to drive your amp that hard to be heard, you're fine. Stay with the 410 if you like the sound of it. This also gives you soom room to grow. It's too bad you couldn't try out the 15 & 2x10 at the same time as the 4x10. I like the extra cone area you get with the 10's, but that's just me. You could also see if GC has one of the 4 Ohm 4x10's (the SVT-410HLF comes to mind, I just got one and love it) and try that out. You'll cut out your room for additional cabs with the head only, but it may work better for you. Just use your ears and don't push the amp into clipping.

    Keep it low,

    Rebel X
     
  10. This is a question of semantics. The case you mentioned is more a case of an underpowered rig than actually underpowering the cabinet. You have a valid point in that if you choose to let the amp be driven into severe clipping it will damage the cabinet. But having enough power and underpowering a cabinet are two different things. If you have to drive the 120 watt amp like you're suggesting, it doesn't matter how much power the cabinet can take, you just plainly don't have enough power (or an extremely inefficient box). This has nothing to do with cabinet power ratings. If the same 120 watt amp was connected to the same cabinet and not driven into clipping, would the cabinet behave any differently than if it was being sent 120 watts by a much more powerful amp? No! Even if the rated power for the cab was 10000 watts. Obviously, you'll get better overall performance with more power and I'd generally not reccommend a 120 watt amp to power a 600 watt cabinet, but from a purely physical point of view, there isn't any such thing as underpowering a cabinet. If you have that 120 watt amp hooked up to a 600 watt cabinet and it isn't loud enough, changing to a cab with a lower rated power isn't going to help. In fact you'll blow the speakers faster in the lower rated cabinet.
    Is what I'm saying here clear? I'm finding it a little hard to express what I'm trying to say.:p
     
  11. Gman

    Gman

    Jan 4, 2000
    Indianapolis, IN
    <Mr. Rogers voice on>
    Amp rated 275 watts at 8 ohms. 8 ohm cab rated 400 watts RMS, 800 watts peak. Good or bad ?

    Would I get better sound if : cab rated 200w RMS and 400 peak?

    <voice off>

    RebelX,

    I nearly did get the 410-HLF. I only decided against it because of portability and not being able to add on. I LOVED to tone of it, but found that I could get pretty close with 10's and a 15.

    Dave
     
  12. No! All other things equal, there won't be any difference in sound. The first situation is absolutely fine, as long as the amp is powerful enough to give you the level you want without clipping (too much). If you're really driving the amp to get the volume you need, you need a bigger amp or more speakers. Of course the number of speakers you can add is limited by the minimum impedence (ohms) your amp can drive.
    In my opinion (and experience) the 410 + 115 setup would be just about ideal for that amp.
     
  13. RebelX

    RebelX Guest

    Oct 27, 2001
    Merrimack, NH
    Do you have all the volume you currently need using the 275 watts (see sidenote below) you have right now? Or is your master volume always pushed up around the 7 or 8 mark. The cab choice is going to to make more of a difference in sound than the extra 175 watts (assuming the cab is linear within its rated power range) if you have the volume you need now. If you don't have enough volume and have to keep cranking it to keep up, the I would suggest you do the cab swap.

    I've always found it better to have enough headroom in the amp to make sure the speakers are getting nice clean power up around the top of their spec'd out range. Then again, I've always played with loud guitarists and drummers. I also like to convince guitarists to turn down by playing my rig louder than theirs (I had gotten out that habit until today, see my "new toys" post).

    Sidenote. Rant On What is it with Ampeg's web site and their specs sheets. The SVT3-Pro specs say that it's 300 watts into 8ohms, not the 275 you and the owners manual mention. The 410HLF web specs say 400/800 watts, while the cab itself says 500/1000. The web specs also says -10db at 28hx while the "Back/Front" picture says -10db at 40hz. Maybe they're just trying to say "get over the specs already and play some music". Rant off

    Keep it low,

    Rebel X
     
  14. cassanova

    cassanova

    Sep 4, 2000
    Florida

    im not saying your wrong on this, cos im definatly no electronics expert, but ive been told by techs and even a few ppl here, that you can underpower a cab and the end result is clipping.


    and no that wasnt all that clear, but i kinda get what your saying.
     
  15. "Underpowering a cab and clipping" is wrong terminology. What it really is is "Pushing your power anp too hard and clipping". It's just that your trying to get too much out of your power amp and your speakers suffer from it. When you push your power amp too hard to get louder, then the power amp "clips", which is harsh on the speaker cones. Simple enough? So, obviously, its not the brightest hting to power a 1000 watt RMS cab with a 50 watt power amp, but if you like the sound, and 50 watts is all you need, and you arent clipping the 50 watt power amp while playing, then there is no problem. (No matter what cab you are using, if you push the power amp too hard, it will clip and hurt the speakers, it doesnt matter how much power the cones can handle...)

    Get it?
    Good
     
  16. Exactly. There isn't any inherent problem with using a small amp to power a cab that can take many times the power. It only becomes a problem if the amp can't give you the SPL that you need. Connecting a cabinet that can take 600 watts to a 100 watt amp will not cause the amp to clip. If that combination will produce 100dB (for example)of clean SPL but you require 110dB, there's where the problems start. If you only need the 100dB or less, there is no problem.
     
  17. MikeyD

    MikeyD

    Sep 9, 2000
    I agree with Spacegoat here. "Underpowering a cabinet" is a myth. The fact of the matter is "underpowering" really means you need more volume than the *system* can deliver. The remedies are:
    (a) get the others to turn down,
    (b) get a head with more power,
    (c) get more or more efficient cabinets,
    ...or any/all of the above.

    Another myth is that overdriving and clipping damages any cabinet. This is not true. I have an old Kustom 2x15 with a Kustom 200 head (probably puts about 50-80 watts sine into it) that I could plug in and clip hard for a year or two and those speakers wouldn't sneeze at it. This is because the speakers can probably take at least 200 watts, yet the head can only deliver about twice its sine rating (i.e., about 160 watts max.) fully clipped. There are no tweeters in this particular situation, I should note.

    - Mike
     
  18. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    I agree with Mike, Spacegoat and Grahams Groove, but I would not say 'underpowering a cab' is a myth, I would just call this phrase misleading.

    If you have an 810 you will expect this thing to be very loud. If you hook up a 50W amp this will not meet your expectations so you crank the amp and it will run into clipping.
    You can say the cab is underpowered, because it does not get enough power to be driven to it's full potential, you can say the amp is underpowered because your situation requires more than those whimpy 50Watts - see what I mean?
    Kind of splitting hairs IMO, but I still appreciate you explanations very much!

    Wether a clipping 50W amp can damage a cab rated 10 or 20 times higher or not - I don't know, I have never tried it out.

    But here comes my question:
    A friend of mine claims that any cab needs to be driven with some minimum amount of power to get a good sound.
    I really don't believe that. Who's right? :rolleyes:

    Matthias
     
  19. MikeyD

    MikeyD

    Sep 9, 2000
    When you are running at an average of 1 watt or 10 watts output into a system built for 100 or 1000 watts, then it's much more likely it is operating in its linear range. When you push a system (amp and/or speaker) near its limits, you are definitely getting into nonlinear regions of operation. Many find this kind of sound "good". It's overdrive resulting in distortion, and sometimes that gives a desirable sound - whether it's from the power amp or from large movements of speaker cones. I myself never feel like I need or want to drive my system near its limits. If, for example, I have a 600-watt amp/speaker combination, I'd have to be sitting somewhere between 500-700 watts (partially clipped) output to get that sound. If I back off my average level even 3 dB, then I'm at 250-350 watts, and back into the linear region. That is not much of a volume difference. Can you see my point? The only way you get that "sound" is when you are driving it hard during peaks or if you are compressing the heck out of the signal and "running it against the rail" all the time. If your friend likes the distortion, then he's right - he likes to push the system to its limits to get that certain edge.
    - Mike
     
  20. Matthias

    Matthias

    May 30, 2000
    Vienna, Austria
    Thanks, Mike!
    As we were actually speaking about PA cabs I guess it's me who is right... :)

    (to be exact we had a little debate on turning down our volume in a small club, I insisted to turn down (bassists are always the wise guys ;)) and he said something like: "you can not play softer than that with our PA because it will sound like s**t, these speakers need a minimum amount of power to move" - crap like that)

    Matthias

    ps: I'm gonna be off for 2 days now, so I won't be able to respond to this one soon.