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power amp selection for mixed rig

Discussion in 'Amps [BG]' started by Bluzeman90, Feb 5, 2013.

  1. Bluzeman90

    Bluzeman90

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    Hello everybody! Thanks to the knowledge of this forum I have purchased and am waiting on a tech 21 vt bass deluxe.now it's time to get some POWER!

    I currently have an ampeg 810e (800w @4 ohms/ ~58hz-5khz) and a hartke 215xl sub module (400w @4 ohms/ 30hz-2.5khz).

    I use a passive peavey grind 5

    Now for the questions.
    I've noticed the 810 (my constant cabinet) is a little lacking in the low end balls, but I love the responsiveness and punch that the sealed cabinet has. Since I already have a hartke 215xl, I figure hey, use it like a sub! So my next purchase will be a power amp of sorts and I'm thinking crossover (variable) would be the best way to run mix matched cabs. My big problem is wattage.my original thought was something about 400w so I don't destroy the 215 when I use them both and just match the other side. Then maybe use the 810 with the amp bridged when using it solo? The crown xls's stood out a bit to me, but I'm really unsure which power rating to get.

    Sorry for the lengthy post, but I figured as much information as possible would probably only help.

    Thanks in advance!
  2. Downunderwonder

    Downunderwonder

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    XTI2000, all the power, all the processing in one. Don't be expecting much from the 2x15, it's a bass cab right? It won't bring huge sub lows to 8x10, maybe only a 2x10 worth of lows depending on how you crossed it over.

    Consider a 3015LF sub can do its work with a single 6" mid, you can see how flawed your biamp plan is looking? You would be carting a huge cab for nothing much gained.
  3. Lowactnsatsfctn

    Lowactnsatsfctn

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    Sell the Hartke cab and get a real sub to go with your PA.


    If you put "sub" bass with enough power through it to compete with an 810, your gonna end up with a big heavy box that smells funny.
  4. bassman10096

    bassman10096

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    You can run most two channel power amps in parallel mode (it's easy on the XLS's). In parallel, you put a single, full range preamp signal into channel one of the power amp. The amp then just sends the signal to both channels, allowing you to control the volume for each separately from the other. That allows you to balance the power and volume you take from each cab according to its rating and best sound. I wouldn't bother with the crossover - it's just not gaining you anything.

    Carrying a 215 to make up for lack of lows in an 810 seems more like a very heavy solution. Maybe the 810 isn't all you want it to be. There are lots of other 810s out there.
  5. oerk

    oerk

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    +1

    Either that and carry both of those big cabs, separately volume controlled _without_ a crossover, or sell both and get one cab that suits your needs.
  6. Bluzeman90

    Bluzeman90

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    Thanks for all the responses guys! Seems like I'm hauling around 110 lbs of nostalgia.

    For those of you that know, the 810e states it has a useable low frequency of 40hz @-10db. Does this mean if I hpf it at 40hz and boost the eq near that frequency by 10+ db I'll get more bass? I've been using a 1976 musicman hd130, which doesn't offer very much as far as features are concerned and I'm pretty sure is not nearly pushing that cab to its potential. Do you think a proper eq with an appropriate power amp would give me better low end? More so with the +10db around 40hz?

    Thanks again guys, you're really the best! :bassist:
  7. Bluzeman90

    Bluzeman90

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    That xti 2002 is a pretty sexy power amp by the way.
  8. bgavin

    bgavin Supporting Member

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    A quality two-channel power amp (mine are QSC PLX) combined with an active crossover (mine are Rane) will do what you want.

    The active crossover is not affected by impedance variations in the cabinets.
    The Rane and similar crossovers offer individual gain controls for each channel.
    The better crossovers go as low as 70 Hz, perhaps lower.

    PLX or similar power amps are 21 pounds, a wide range of power ratings, and are professionally reliable.
    Both active crossover and PLX power amps fit in a standard rack.
    The Rane are 1RU and the PLX is 2RU.

    The Carvin HD series "might" fit into a more shallow effects rack.
    Check the measurements closely to be sure.
    I've not used the Carvin, but the design is appealing, and the price is right.

    By design, a sealed 810 won't have a big bottom. It is what it is.
    The charts I've seen are not authoritative, but appear to roll off at the sealed rate of 12db/octave from 100 Hz and down.
    You have to do your homework to figure out your requirements in the bottom octave.
    Many players don't require much between 40 and 80 Hz, others do. YMMV.

    3015LF drivers have an Fs around 42~43 Hz.
    These are wonderful drivers (I own several), but they are limited to the 4-string low E under high power use.
    The current version of 3015LF requires nearly 8 cubic feet to reach its full bass potential. This is a BIG box.
    Check into the response charts for the fEarful at 40 Hz and notice the roll-off.

    For almost 10 years I played a pair of 1x15 true subs + tens + rack combination for the big bottom with a 4-string.
    This is useless in bars, but very useful outdoors for gigs without big PA support.
    Hauling all those cabs and rack is heavy and annoying, especially in bad weather.

    Think it through before yielding to GAS and rushing into something expensive.
  9. 5 Wire

    5 Wire

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    Yes and +1 for the XLS. Affordable, reliable, versatile and ballsy. I have had mine in my rack for 2 years and never been disappointed.

    Like you I have more than one cabinet so, I use it with as a stereo amp with a dual 15 band EQ. Channel one to my main cab(s) and channel 2 to whatever or nothing depending on the size of the gig. EQ's are easily gotten on ebay.
    Good Luck!
  10. Gearhead17

    Gearhead17 Supporting Member

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    -10db at 40hz: I used to think that was true, however, you have to realize this spec is telling you where the cabinet is trailing off for low end response. Boosting here is going to push your cabinet very hard to reproduce sounds it is not truly designed for. It's a waste to do this.

    Musicman HD130 - I am guessing 130 watts of tube tone at 4 ohms? This may be the culprit for lack of low end. Tube amps do NOT have the ability to stay clean at middle to higher volumes. They will distort. The distortion will slowly knock off low end response based on how the unit was designed and how many watts you are dealing with. If you want more low end, you need to go MOSFET for the amp section. Or, go for a bass tube amp that equals 300 watts or better.

    The Hartke 215 is not going to add much low end below 60hz to your overall rig. Invest in a different head for the Ampeg 810e and see what happens.
  11. Downunderwonder

    Downunderwonder

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    bgavin gave you a good serve of reality check.

    The 810e aren't the greatest cab for 5 string when guys try to get sub lows out of them. You could get a big GK with a 5 string button to "boost lows" but you will blow your drivers. Do a search.

    Since you really like your 8x10 you should invest 100 and some in a f-deck hpf. Use that to cut everything below 60 hz and see how it goes with a bass boost on your EQ. It may still flab before you get enough low B.

    You could invest in PA gear and a much much smaller cab for monitoring. It wouldn't be any worse than lugging 8x10 and 2x15 etc.

    What is your gigging situation?
  12. Bluzeman90

    Bluzeman90

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    My gigging situation is mainly small bars, etc. We play VERY heavy blues with a loud freaking drummer, so just about everywhere we go our stage volume bleeds into the audience quite a bit. Some small places we just Mic vocals and bass drum. We are trying to get some bigger good though (might have some arena openings available :hyper:)

    All in all, I think you might be right about the tube amp. That's why I'm looking for a power amp that will complement my cabinet well, and I guess I really haven't heard the 810 open up so I might not even need the 215....

    So glad you guys are here.

    On another note, the can states 800rms, if I ran 700 clean to it, is it still clean from the cab, or is it going to be a fart box? Since I haven't had the pleasure of running one wide open with that kind of wattage, what can I expect from this particular cab (if anyone knows)

    Thanks guys!
  13. oerk

    oerk

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    800W is, most likely, the thermal power handling of the cab. If it is like most cabs, it's going to distort a lot sooner (half the power is a good guess). Manufacturers tend to state the thermal power handling of their speakers (because it's the bigger number, surprise!), not the mechanical.
  14. bgavin

    bgavin Supporting Member

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    If you have full PA support, a big stage rig interferes with the house system, which earns you the ire of the sound man.
    Consider a standard rack with components of your choice, and a variety of speaker cabs for different venues.
    I take bass horns and tops for a big sound outdoors, and a single 10" for intimate restaurant venues.

    Tall 'N Skinny cabs offer a lot of benefit, so I roll my own.
    Going "tall" is much more space-friendly on a tight stage.
    They wheel about easily, have a small stage foot print, and fit under micro amps such as the LM-III.

    If you want Big Noise and Big Bottom, you have to use Big Cabs.
  15. Bluzeman90

    Bluzeman90

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    I see a lot of people going this route. I've learned from guys that played in the 70's and 80's, the used massive rigs with massive power. I've already obtained some different cabs, hartke 215xl 410xl, peavey 215 (needs some love), musicman 212 (same as peavey), and the 810e. No one tens, but there are times I can be more subtle.

    My question to you is, how do you (or anyone else for that matter) hear you over a drummer and guitar. I've battled being able to hear myself and the drummer really counts on hearing me as well. Haven't met a competent sound man in a while so maybe that is the problem?

    Any how, thanks for the reply and that is the route I'm heading towards. Very modular.

    On another thought, are in ear monitors worth the money? I've seen bands use them and maybe that would fix a lot of problems?
  16. Gearhead17

    Gearhead17 Supporting Member

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    A competent sound man with decent monitor cabinets on stage will solve all of that. I set my bass rig on stage so I can hear it. If someone else wants to hear you, ask for bass in the monitor speakers. Granted, the monitor cabs need to be good enough to pump out bass tones.

    IEM systems are worth the money if you buy decent gear, put in the time to learn how to use it, and work together as a band on it. The idea is less stage noise and everybody can hear everybody no matter where they stand.
  17. bgavin

    bgavin Supporting Member

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    In-ears: do use two or there is a serious risk of deafness as you turn up the in-ear to compensate for noise in the other ear.
    Hearing on stage: lift cab up to ear level. Or, cage the drummer in Plexiglas.

    When I do FOH for youth bands, caging the drummer is very worth while.
    This has the added advantage of keeping drummer-wash out of the stage mics.

    I play a geezer cover band, so my appearance doesn't count for much.
    I have a set of noise-blocking headphones that look dorky, but work when needed. Ear plugs suffice most of the time.
    But... we don't play at youth loudness levels, and we use a MIDI drummer that we can turn down. :D

    Look first at what provides you the greatest payback.
    Is it Size, Bottom, Loudness, Footprint, Tone, or ??
    These features are where multiple cabs come into play.
    I favor tall 'n skinny, or vertical stacks to save foot print space and increase horizontal dispersion.

    One amp, that I can understand, but one cabinet, that is not civilized, it is not generous. -Sheik Ilderim
  18. oerk

    oerk

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    At first, I was bringing a 1x15 simply to bring the 4x10 up to ear level. The 1x15 itself was totally unnecessary, but I finally could hear myself.

    Nowadays, I'm relying on tiltback combos and cabs, positioned at the side and firing across the stage. The drummer still needs a bit of bass in his monitor, but the rest of the band can hear me fine.
  19. Bluzeman90

    Bluzeman90

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    Thanks for the responses guys!

    I've been doing some research and some calculations looking at power amps because I'm getting a lot of different opinions on matching watts power to watts cabinet. The 810 is 800 watts, as I understand it, that is a constant, doesn't change. Now we get into the headroom issue. Crown explains that you want x amount of db spl extra for peaks, but should I realistically limit the amp to 800 watts so the peaks go over into "program power". Or should I get 1600 watts and run it to taste. Our even less so the peaks don't exceed the 800watts rating?

    I know there is a lot of bs from manufactured as far as accurate power ratings, but this is a popular cab and someone might know its "real" rating, etc.

    Side note, did an spl to watts calculation on crowns website. For 100 db at 14 meters with a cabinet with a sensitivity of 100db @ 1w/1m is 798 watts. Don't know if that helps...
  20. bgavin

    bgavin Supporting Member

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    I own three QSC PLX, two are 3002 which are 550w into an 8 ohm load, each channel.
    These are capable of driving a 10" driver without blowing it up, cuz I don't over drive the ten.
    You don't have to turn it all the way up...

    Most power circuits are 15 amps, so you are not going to get anything more than 15a*120v = 1800w input to your amp.
    I've not yet seen a stage that has a 240v/50a arc welder circuit for bass players... :D
    The laws against perpetual motion are still in place, so you are not going to get 3000w output from 1800w input.
    (This opens the door to TB nitpicking about instantaneous power, ad nauseum. Go for it.)

    Most of the noise you make is with the first 100 watts.
    Every doubling of power is worth +3dB to your ear. +10dB power sounds 2x louder to the ear.
    Every parallel-doubling of speakers adds +6dB to the noise level, at the same amplifier output voltage.

    The advantage to a big power amp is a higher output voltage.
    This is useful to drive series-parallel wired cabs (i.e 4x10) to their rated power.
    Very few cabs will produce bass output at full rated power, due to speaker limitations.

    Use more cabs.

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