What Size Amp?

[MartinH82 0]

Hi Guys and Gals,

 

I am just starting out with mobile disco'ing and have 90% of the equipment i need.

 

The problem i have is that i am uncertain as to what size amp i will need.

 

I am running 2 Dap K-112 tops with an output of 300wrms each and 2 Intimidation bins with 375wrms each.

 

Could anyone advise me on the basics to run these as when it comes to outputs and rms i just end up confusing myself. Any tips on what makes are recommended would also be greatly appreciated.

 

Many thanks.

 

Martin

[dj_dex 0]

Assuming your amp only has two outputs, one for left & one for right, and you pair your speakers two to a channel giving you 675Wrms/channel I'd be thinking of a 1000W amp (500W/channel) , that way you know it can't blow your speakers. Blowing the amp is much less of a problem nowadays, they all tend to have overload protection.

 

As long as your amp can't supply more than the rms rating of the speakers you connect, you should be fine.

Personally I run a 1000W Carlbro mixeramp into 2x 400W Peavey's and 2x 300W Gemini's.

 

Edited April 1, 2009 by dj_dex

[Andy Dunn 0]

Hi Guys and Gals,

 

I am just starting out with mobile disco'ing and have 90% of the equipment i need.

 

The problem i have is that i am uncertain as to what size amp i will need.

 

I am running 2 Dap K-112 tops with an output of 300wrms each and 2 Intimidation bins with 375wrms each.

 

Could anyone advise me on the basics to run these as when it comes to outputs and rms i just end up confusing myself. Any tips on what makes are recommended would also be greatly appreciated.

 

Many thanks.

 

Martin

 

Oh well here we go again!,

 

We could really do with some more information before we can advise you further.

 

1. What impedance are your speakers, ie 300w rms into 4 or 8 ohms?

 

2. Do you want to run everything off one amp or do you want to run your system 2 way active, ie one amp

for your bass and one amp for your mid-hi?

 

3. What is your budget for your amp/amps/x-over?

 

Also and this is where you will find varying opinions,some will say use an amplifier which is lower powered than your speakers,some will say use an amplifier which is of a higher rating than your speakers.

 

Believe me you are far more likely to damage your speakers with an amplifier which is not powerful enough to run them than one which has plenty of overhead available.

 

I hope this helps and we await your reply!

[superstardeejay 0]

As long as your amp can't supply more than the rms rating of the speakers you connect, you should be fine.

 

This is misleading information. An amp that is even very much smaller than the speakers can damage the speakers if the amp is run too hard.

 

 

[Robster 0]

An amp that is even very much smaller than the speakers can damage the speakers if the amp is run too hard.

 

I totally agree with superstardeejay

In my experience this is very much the case and what i used to see all the time in home Hi Fi ..small amps driven too hard losing control and clipping resulting in blown drivers.

[Andy Dunn 0]

Funny,I could have sworn that's what I posted earlier in this thread !!

[dj_dex 0]

This is misleading information. An amp that is even very much smaller than the speakers can damage the speakers if the amp is run too hard.

 

I bow to your greater knowledge - it's never happened to me tho' on several rigs and many many cars - surely if you 'run the amp too hard' you're gonna get some warning signs, those flashing red lamps and the hideous sound quality as it clips your signal? Ignore those and you deserve all you get!

 

[TonyB 0]

I bow to your greater knowledge - it's never happened to me tho' on several rigs and many many cars - surely if you 'run the amp too hard' you're gonna get some warning signs, those flashing red lamps and the hideous sound quality as it clips your signal? Ignore those and you deserve all you get!

 

I agree with you but its a case of hitting your head against a brick wall. Little wonder sound techies despair at DJ's

[superstardeejay 0]

you're gonna get some warning signs, those flashing red lamps

 

Yes! It sounds like you're a responsible person!

 

However, this and many forums like it are awash with people who report they have blown their speakers and thought they were safe because they had a tiddly little amp!

 

It's very easy to get caught up in the heat of the moment, nudging the volume up and up as a venue gets fuller and fuller and the clients get drunker and noisier..and you get deafer and deafer!!

 

I once blew my tweeters in my lounge after a couple of cans of beer and some exuberant dance music.

 

[TonyB 0]

 

However, this and many forums like it are awash with people who report they have blown their speakers and thought they were safe because they had a tiddly little amp!

 

 

To be honest I've never seen such a thing (and I subscribe to quite a few forums both for DJ's and pro sound). Usually when asked the amp is more powerful than the speakers.

[Kingy 0]

Same old same old.

 

I wish I had a pound in my back pocket for every driver I replaced at the shop destroyed by DJ's (never sound engineers funily enough!) over driving them. Wanting a quart from a pint pot. And yes, many had square waved the amps destroying the drivers, crossovers and tweeters. Loads!

 

The guys with the bigger (better designed) amps and bigger rigs hardly ever seemed to be in for repairs, odd that!!!

[superstardeejay 0]

I wish I had a pound in my back pocket for every driver I replaced at the shop destroyed by DJ's

 

Is that all you charge?

 

 

I agree which is why I said that earlier.

 

I have a nice couple of cabinets here in the workshop that are rated 300W each RMS, ie a 250W 15in woofer and compression driver.

I gained them after the customer almost set fire to them with a 100W/ch powered mixer he had pushed a little too far. He couldnt afford to have the speakers repaired so I got them for free.

 

He said he'd be using a 50W acoustic guitar amp to run his disco from now on, so he had me service that as well.

 

 

 

 

 

[norty303 0]

To comment on your specific speakers, I've got a pair of K112 that i use for monitors or very small systems that go out. they are ok, and I've run them off a selection of amps (mostly QSC RMX2450 and PLX3402 giving 450w and 700w at 8ohms respectively) I've found that they take the power ok, but they tend to start sounding quite nasty before the amp gets up near its max output, and with all these things, you should let your ears be the judge of whether they sound comfortable or not. My biggest issue with them is that they have an exceptionally bright top end on them (although they have the sparkle you get from a dedicated bullet tweeter over a compression driver), enough that I couldn't ever take them out without an EQ to accompany. As a stand alone cab they are not very nice sounding at all (imo). That said, they are good for floor monitors for vocalists as the vox cut through well, but lack any sort of punch in the bass and lower mid region despite drastic EQ, which only pushes them closer to any limits they may have.

 

So, in summary, use a big amp if you want, but treat them carefully and you shouldn't have any problems. And don't be scared of big amps, it takes a reasonably sustained amount of abuse to blow a driver, short peaks that go way over the rating of the driver should not present it any problems if fitted in a cab that loads it correctly. High pass filters on bass bins are critical here.

 

For what its worth, the smallest amps i use now are PLX3402 (2x700w at 8R, 2x1100w at 4R) and these get used to drive everything from bass bins to just compression drivers (rated at 80w each in some cases) The only blowups I've ever had were 2 18" drivers in a bass cab that was getting just under 2.5k from a bridged RMX2450 and that was due to clipping of the amp. Had run flat out for the previous 6 hours (and many previous events) with no problems at all. Would probably only have been the one driver were it not for the fact cab was a bandpass design where one driver failing caused the cab characteristics to change enough for the other to be unloaded.

Edited April 4, 2009 by norty303

[jeffwall 0]

2 options.....

 

option 1

 

run the whole set up with 1 amp, presuming their is a crossover in the subs at 100hz or similar?

 

If their is, your Amp will see a 4 ohm load each side, and give power to each side at 4 ohms load.... most amps will handle this 4 ohm load easily, however it comes at a price, because the lower the OHMs the amp is driving, the more heat it will create... simply because its working harder than say the same amp on a 8 ohm load.

 

Option 2

 

Run 2 amps, one for the bass subs, and one for the tops.

This will mean that each amp is seeing 8 ohms and wont work as hard.

 

As a general rule of thumb, your amp/amps should be rated at approx 30 percent HIGHER than the speakers. And I personally would run the amp at 3quarters output volume.

 

So your set up with 375watts bass plus 300 watts mid/high will give you a total of 675 watts per side RMS

 

The amp I would choose would be 800/900/1000 watts at 4 ohms!

option 2 would require 2 amps at 500 watts per side into 8 ohms

 

option 2 would mean you would need a crossover/speaker controller probably

 

But its a far better rig imo

Edited April 5, 2009 by jeffwall