How Many Speakers?

[djmick 0]

Needing some advice here, I,m using a peavey ipr1600 and want to use four speakers, All speakers are rated at 300w rms, The first two speakers have a "Link" output (NJD,s), the other speakers just have the normal input,

Question is, will this overload my amp? will it harm the speakers? is it worth it (It does sound better when I have had a quick preview),

All the speakers are also 8ohms but i read somewhere that 4 speakers take it to 4ohms from the amp?

It,s all very confusing this ohm,s stuff,

So here,s the set up,

Speaker cables from amp go to NJD,s, other speaker cables go from NJD,s Link to the other two speakers,

is this ok to do?

 

 

[McCardle 1]

2x 8ohm speakers = a 4 ohm load to the amplifier

 

You are (I assume) connecting two speakers to the left channel, and two speakers to the right channel, therefore the amplifier will be running 4 ohms per channel - a load which is perfectly compatible with the majority of amplifiers.

 

In addition, the IPR1600 is also specified to take loads down to 2 ohms, and so running 4 ohms off each amplifier channel will be perfectly OK. In this situation, you would get 530 watts RMS per channel from the amplifier according to its specification on the Peavey website

 

Yes, you can plug the NJD's into the amplifier, and then link out of the NJD's and into the other speakers. Just make sure that you use decent twin core cable throughout, and not bell wire or signal leads!

[djmick 0]

Thanks for that, yeah, they will be linked by speakon cables (god quality).

The only concern i had was that the speakers are rated at 8ohms and the amp would be turning out 4ohms, or have i got that wrong?

 

[McCardle 1]

The amplifier doesn't 'turn out' 4 ohms

 

The ohms number is simply the amount of 'load' or resistance that is presented to the amplifier

 

If you were to connect 1x 8 ohm speaker to each channel of the amplifier, then the amplifier would have an 8 ohm load connected to it.

 

If you connect 2x 8 ohm speakers to each channel (as you are doing) then the combined load of two 8 ohm speakers, equals a total of 4 ohms to the amplifier

 

Most modern amplifiers will happily run into 16 ohms, 8 ohms and 4 ohm loads, some newer amplifiers will run right down to 2 ohms (which would be 4x 8 ohm speakers per channel!!!)

 

The only thing which changes depending on the number of ohms connected to the amplifier is the amount of power (watts rms) which the Amplifier produces. Generally the lower the ohms number, the more power that the amplifier will output.

 

Think of Amplifier vs Ohms load as a water tap analogy on a sink.

 

With 8 ohms connected the tap is only half open, so you get about half of the available capacity flowing through the tap.

 

With 4 ohms connected the tap is open further, and so more water flows through

 

With 2 ohms connected, the tap is fully open as far as it goes, so you get the maximum flow

 

So, in other words, your amplifier will produce more power (wattage) when it is connected to 2x 8ohm speakers (a total of 4 ohms) per channel, than if it was just running with 1x 8 ohm speaker per channel. However the total output power would be split equally between the two speakers which are connected.

 

 

 

[djmick 0]

That,s brill, I doff my cap to your knowledge sir,,

[DJTREV 0]

On a cautionary note,dont push too much power to your speakers as they are only classed as 300w rms.

[djmick 0]

Yeah I was pretty careful to watch my levels, keeping it well out of the red, I must say it may just be my ears playing tricks but it deffinately sounded better, The only problem is that when you play a badly encoded mp3 it stands out a mile,

[McCardle 1]

I must say it may just be my ears playing tricks but it deffinately sounded better

 

Probably just a placebo effect . Adding extra speakers will sound louder as it will drive extra wattage from the amplifier, and it will sound more linear as the sound is being spread across four speakers, rather than two, however it won't increase the quality of the amplifier or magically make it sound better.

 

The only exception to this point would be if the second set of speakers you had connected was of a higher quality and had a better SPL rating than the other pair, as by connecting these you would get an improved response and an overall clearer sound, and it would be noticeable over a lower quality pair, especially when run alongside them from the same source.

 

When choosing an amplifier and speakers its always a good idea, to buy a bigger system than you actually need, so this way you will be getting the power output you need without stressing either the amplifier or speakers. Needless to say, a room that requires 1000W of audio power to make for useable sound levels, would be far better served by a 2000 watt amplifier running at 50% of its capacity, rather than a 1000 watt amplifier running flat out at 100% of its capacity

[Megasong 0]

Probably just a placebo effect . Adding extra speakers will sound louder as it will drive extra wattage from the amplifier, and it will sound more linear as the sound is being spread across four speakers, rather than two, however it won't increase the quality of the amplifier or magically make it sound better.

 

The only exception to this point would be if the second set of speakers you had connected was of a higher quality and had a better SPL rating than the other pair, as by connecting these you would get an improved response and an overall clearer sound, and it would be noticeable over a lower quality pair, especially when run alongside them from the same source.

 

When choosing an amplifier and speakers its always a good idea, to buy a bigger system than you actually need, so this way you will be getting the power output you need without stressing either the amplifier or speakers. Needless to say, a room that requires 1000W of audio power to make for useable sound levels, would be far better served by a 2000 watt amplifier running at 50% of its capacity, rather than a 1000 watt amplifier running flat out at 100% of its capacity

 

A few points worth mentioning here, some pretty pedantic but when discussing technical matters it is often best to ensure that everyone is using the correct terminology to avoid misunderstandings.

 

1) Adding an extra pair of speakers with the same sensitivity as the originals will give you an additional 3dB before considering the extra power the amp will be able to deliver, so you would expect an additional 6dB at 1M from the speakers if all else remains the same (the amp delivering twice the power through the paralleled load of the additional speakers)

 

2) There are a lot of misunderstandings about SPL so just to clarify; The reference SPL is how many dB the speaker will deliver at 1M with 1Watt of power, this should ideally be tested using weighted pink noise. The Maximum sustained and peak SPLs are what the speaker is capable of delivering under these conditions. If a second speaker is 10dB more sensitive that speaker will sound twice as loud as the original and as stated, if it is a better quality unit this will improve the overall sound. If the new speaker is any less than 3dB more sensitive you may just about notice an improvement but not by much.

 

 

3) Audio Power has a complicated relationship with your amplifier and speakers. Most of the speakers we (DJs) will be using will be between 0.5% and 1% efficient. An average venue needs about 4-5 watts of audio power to fill it with loud music, hence an amplifier of about 1000W would be needed if the speakers were 0.5% efficient. Standing next to a rocket taking off would be unlikely to present 1000W of audio power! Apart from the technical error using audio power as a reference the point however largely stands but.... Since it is actually audio power that is 'heard' and not the amplifier's power the efficiency of your speakers will play a much bigger part in perceived loudness than the amplifier power.

[djmick 0]

Ta for the replies guys, all very helpful,,