what size amp ?

[mkindy]

what size amp do you run ?

open question i know..... i have a 600w amp so thats 150 per channel at 4ohms, doesn't seem man enough to me, just dping local village halls, birthday / weddings.

[Daryll]

Bi amp system for me.
W-Audio horizon 1300 for tops. http://www.djanddiscostuff.com/sound-c16/amplifiers-c40/w-audio-w-audio-horizon-1300-amplifier-p501
Quoted power.
Stereo power: 2 x 430W @ 8ohms

Stereo power: 2 x 650W @ 4ohms

Bridge power: 1300W ( to be taken with pinch of salt.........;) )


Behringer EPQ 2000 for subs http://www.thomann.de/gb/behringer_epq_2000_europower.htm?sid=c174aafca08e0 f1130d094049b263ab8

Quoted power
2 x 700 Watts into 4 Ohms; 2 x 500 Watts into 8 Ohms ( er...more salt...........;) )

Good for 100 people max , village halls WMC , small /med weddings.

Daryll

[Corabar Steve]

Surely this will depend on your speakers capabilities, which you haven't told us.

[super-hero]

I run QSC pl236 amps that do 1200w per side at 4ohms. I run one amp for the bass cabs, and one amp for the top cabs. I have a loudspeaker management system controlling them.
This seems a bit overkill but I use the amps and lms to run various different setups, and it means I can change all the settings at the press of a button.

[Paul James Promotions]

You want to be feeding speakers with at least their RMS rating, ideally a bit more.

[Excalibur]

Surely this will depend on your speakers capabilities, which you haven't told us.

Correctamundo. Without this information we're simply guessing. Jamie's advice tallies with what many people recommend, and I wouldn't disagree with it for a second.

Please remember to compare like with like, ie RMS values for the amp with RMS values for the speakers. Let's pick a couple of values out of the air. If your cabs were rated at 150 watts RMS, and they were 8 Ohms, I'd say a suitable size for the amp would be anywhere between 150 Watts RMS and 300 Watts at 8 ohms.


Give us the ratings of your cabs, and we can give some better advice.

[mkindy]

i'll fill in the details later when i get home and have a look at the ratings, i currently have my amp plugged into the subs then into the tops, do most people run two amps then ?

[Excalibur]

i'll fill in the details later when i get home and have a look at the ratings, i currently have my amp plugged into the subs then into the tops, do most people run two amps then ?

Most? Probably not ( though running a poll on it might be informative ), although there is little doubt that this is by far the best solution, especially if the frequencies are split by an active crossover. It has the bonus that should an amp die in this mode, it is possible to wire as you presently do, and finish the night on one amp, but all speakers.

Often it's possible to keep your existing amp ( usually to drive the tops ) and buy a more powerful one for the subs. This does at least remove some of the financial outlay.

[Daryll]

There are loads of permutations of amp/speakers, active/passive , and a combination of both
I use a bi amp system for two reasons , firstly more control over power levels to subs and tops , via the crossover , there fore the sound can be adjusted to the room, and at a push , if one amp fails , the system can be run from one amp , at reduced power , but not something I would like to do for a whole gig for reasons set out below
Secondly , I made a mistake..............tops are 4 ohm cabs , so are the subs , so wired amp-sub-top would have the amp seeing 2.6 ohms , you need a good quality amp that can run at 2 ohms nominal.

Daryll

[Excalibur]

There are loads of permutations of amp/speakers, active/passive , and a combination of both
I use a bi amp system for two reasons , firstly more control over power levels to subs and tops , via the crossover , there fore the sound can be adjusted to the room, and at a push , if one amp fails , the system can be run from one amp , at reduced power , but not something I would like to do for a whole gig for reasons set out below


Agreed totally.


Secondly , I made a mistake..............tops are 4 ohm cabs , so are the subs , so wired amp-sub-top would have the amp seeing 2.6 ohms , you need a good quality amp that can run at 2 ohms nominal.

Daryll
I wonder if you may have made another one. If wired in parallel, the two fours would present a two ohm load to the amp. Joining an eight and a four gives 2.66 Either load would require a 2 ohm capable amp of good quality. That's not for the fainthearted, the novice, or me.

If the subs have a high pass filter, and you run the tops from that, then often the cabs are effectively running as one unit, but in two separate boxes. ( That's not a very good description, but I understood it )

[Daryll]

Agreed totally.


I wonder if you may have made another one. If wired in parallel, the two fours would present a two ohm load to the amp. Joining an eight and a four gives 2.66 Either load would require a 2 ohm capable amp of good quality. That's not for the fainthearted, the novice, or me.

If the subs have a high pass filter, and you run the tops from that, then often the cabs are effectively running as one unit, but in two separate boxes. ( That's not a very good description, but I understood it )

yep, I was typing before brain engaged.............;) , you are right peter , 4 + 4 = 2 ohm load , and 8 + 4 = 2.6.

[mattydinx]

what size amp do you run ?

open question i know..... i have a 600w amp so thats 150 per channel at 4ohms, doesn't seem man enough to me, just dping local village halls, birthday / weddings.

While everyone thus-far has been correct in saying your amp's output power should equal or preferably exceed your speaker's given RMS rating at it's given impedance, You need to remember that power/wattage is no indication of sound volume level or quality. That all depends on the efficiency and build of your speakers.

For example, say you're currently feeding your speakers 150w, they've got a sensitivity of 98dB and you're measuring how loud they are 1m away. You'd get an approximate reading of 123dB. Say you upgrade your amplifier to double that, so 300w per speaker, taking the same reading your max SPL would only increase by 3dB to 126dB. Not a massive leap, although 120dB+ is still bloody loud.

Don't get too hung up on how powerful your sound system is, So long as it sounds crisp and clear, no distortion and you aren't driving your amp to clip or red-lining on your mixer you'll be alright. If you're finding that your PA doesn't go loud enough for your current needs, or you're coming close to maxing everything out (no headroom), you may need to look for a better-matched amp, or better speakers. That being said, you can often do more damage to a loudspeaker with an under-powered amp running into clip than you can by over-powering/driving the same speaker into distortion.

I was working a hotel a few years ago along with another operator who was bragging about his "4000w RMS rig" (claiming he'd even shattered windows with it because it could go so loud! :daft:) At the time my PA was powered by a 1200w Amp (600w RMS per channel @ 4Ohm), we had similar-sized rooms yet I'd have put money on it to ask anyone which system sounded better (clearer, deeper/punchier bass, etc)...they'd have said mine.

I discovered last year when I got my new PA that while technically it's more than twice as powerful as my old rig, because it's of much higher quality and the music is so much clearer, most of my gigs are actually quieter than before.

[mkindy]

ok i'm home and just had a look

subs are 300w RMS @ 8ohm
tops are also 300w rms @ 8ohm my amp

i power them from one 150w, 8ohms per channel amp, pluged into the sub then sub to tops

so bigger amp required then, so question is

anyone got a nice very cheap amp for sale please ;-)

[mattydinx]

You're probably presenting a 4Ohm impedance to your amp by running your speakers like that, so it's more likely that you're getting 300w p/c @ 4Ohm.

What are the make & model of both your speakers and your amp?