PA Wattage Help

[thex-faders]

I have recently bought some Carlsbro 600 watt sub speakers and a 1200 watt amp to power them.
Before buying these subs my system consisted of two NJD Celestion 300 watt speakers and 600 watt amp
What i want to know is if anyone would recommend the best way to set up the system?
Should I just use the 1200 watt amp to power the subs and overheads by linking them through the sub output?
Or should i power the subs with a 1200 watt amp (turned down) send the signal to the 600 watt amp which will then power the overheads?
Any other recomendations will be welcome as im not too hot on power ratings etc.

Thanks all

[Paul James Promotions]

Firstly, hello and welcome to the forum. Would be good if you could tell us a bit about you in the Newbies section :)


Or should i power the subs with a 1200 watt amp (turned down) send the signal to the 600 watt amp which will then power the overheads?


Wiring it up this way runs a risk of damaging your equipment.

With your current set up, I would use your small amp to run your top speakers, and the bigger amp to run your subs. Then, ideally add a crossover to your system which splits the bass and mid/hi frequencies before sending them to the amps, giving you a cleaner sound and more headroom.

Regards,

Jamie

[spin mobile disco]

Turning down an amp doesnt provide less power to them just less volume. This can be very risky to do unless speakers have very high peak value's.
Probably better off doing what jamie said split the signal before amp stage then feed highs to 600 watt amp and lows to 1200 watt amp. I personally dont use a crossover and simply run out 2 signal leads to each amplifier and have 1 amp for tops 1 amp for bottom. Much easier and cheaper to do but it does waste a bit of power. But only a problem if your short on power.

[thex-faders]

Thanks for both of your replies!
So how would i split the highs & lows without a crossover?

Cheers again. Have posted my set up in newbies section.

[Paul James Promotions]

Turning down an amp doesnt provide less power to them just less volume. This can be very risky to do unless speakers have very high peak value's.


As i understood the original post, he was thinking of running from the output of the large amp into the input of the small amp. Could be wrong though, just how it reads to me.


Thanks for both of your replies!
So how would i split the highs & lows without a crossover?



If either of your amps have a link output, you can simply 'daisy chain' the inputs. If not, does your mixer have more than one output?

[Corabar Steve]

Firstly, hello and welcome to the forum. Would be good if you could tell us a bit about you in the Newbies section :)

He already has :P

[Solitaire Events Ltd]

He already has :P

He hadn't at the time though. ;)

[TONYTIGER]

You say the mixer has a sub output this is really like a xover so feed this to the 1200w amp is this amp 600w per chan into 4ohms and what ohms are the subs i would think 8ohms if that is the case you will be safe as the amp will only deliver about 350w per side under this loading.Then just take your normal output to the smaller amp to feed your other speakers you can tweek on your eq,or as the other lads have said buy a electronic xover about £70 for a behringer. TONYTIGER

[Excalibur]

You say the mixer has a sub output this is really like a xover so feed this to the 1200w amp is this amp 600w per chan into 4ohms and what ohms are the subs i would think 8ohms if that is the case you will be safe as the amp will only deliver about 350w per side under this loading.Then just take your normal output to the smaller amp to feed your other speakers you can tweek on your eq,or as the other lads have said buy a electronic xover about £70 for a behringer. TONYTIGER

I think he actually means the output from the sub speakers, which is much more dangerous, if used wrongly.

My easiest way would be 1)-1200 watt amp into subs, linked up to tops from sub output.

You asked for best, which is undeniably 2)-get an active crossover (£70 plus leads), 1200 into subs, 600 into tops, job done.I was amazed one night, when out with mine and five minutes to spare, set up as in 1) sounded very good and thought I had wasted my money on the crossover. I then set up as in 2) and realised I hadn't!:D If you are unsure about anything, just ask on here, somebody will help.

[thex-faders]

Citronic CDM 8.4 Mixer with:
XLR Balanced Output
Unbalanced Output
Booth Output

So i am currently using balanced XLR to amp.
If i wanted to power both amps i would use balanced XLR to 1200 watt amp for subs and use unbalanced output to amp, to power tops?

Or do you guys recommend Balanced output to 1200 watt amp, send to subs and subs send to tops. (Subs have speakon output for linking with tops)
Bearing in mind the tops are only 300 watts & subs 600 watts, so would this blow the tops speakers using a 1200 watt amp?

Hope thats cleared up the issues over the mixer output etc.
Cheers again

[Tony Scott]

Turning down an amp doesnt provide less power to them just less volume. This can be very risky to do unless speakers have very high peak value's.
.

Turning down the volume controls on an amp sends some of the input signal to ground via a variable resistor (potentiometer) which decreases the voltage being supplied to the input stage of the amp.
This DOES provides less power to the speakers because an amp will only give an output directly proportional to the supplied input.


Citronic CDM 8.4 Mixer with:
XLR Balanced Output
Unbalanced Output
Booth Output

So i am currently using balanced XLR to amp.
If i wanted to power both amps i would use balanced XLR to 1200 watt amp for subs and use unbalanced output to amp, to power tops?

Or do you guys recommend Balanced output to 1200 watt amp, send to subs and subs send to tops. (Subs have speakon output for linking with tops)
Bearing in mind the tops are only 300 watts & subs 600 watts, so would this blow the tops speakers using a 1200 watt amp?

Hope thats cleared up the issues over the mixer output etc.
Cheers again

Run the balanced XLR to your 1200w amp and link from your 1200w amp to the 600w amp. Supply the bass from 1200w & tops(overheads) from the 600w amp.

or as tony t said get a 2way electronic x-over from behringer, if you go down this route ask and you will be given advice on setting this up. really easy!

:)

[Excalibur]

Turning down the volume controls on an amp sends some of the input signal to ground via a variable resistor (potentiometer) which decreases the voltage being supplied to the input stage of the amp.
This DOES provides less power to the speakers because an amp will only give an output directly proportional to the supplied input.



Run the balanced XLR to your 1200w amp and link from your 1200w amp to the 600w amp. Supply the bass from 1200w & tops(overheads) from the 600w amp.

or as tony t said get a 2way electronic x-over from behringer, if you go down this route ask and you will be given advice on setting this up. really easy!

:)

Pedants corner, and I stand to be shot down in flames, but is there actually a sub output from a Citronic8:4 ? Two of us have already suggested best option is active crossover plus separate amps for top and bottom.

Mr Scott, we have had this one before, about how to link amps. When I was a lad, everything had a slave out. I am dubious about joining inputs to inputs, rather than outputsto inputs, which is fine by me. Not spoiling for a fight, honestly, just elucidation.

[TonyB]

Pedants corner, and I stand to be shot down in flames, but is there actually a sub output from a Citronic8:4 ? Two of us have already suggested best option is active crossover plus separate amps for top and bottom.

Mr Scott, we have had this one before, about how to link amps. When I was a lad, everything had a slave out. I am dubious about joining inputs to inputs, rather than outputsto inputs, which is fine by me. Not spoiling for a fight, honestly, just elucidation.

If an amp has two inputs such as XLR and TRS jack (or phono), they are connected internally in parallel. Using one as input and one as output is much the same as using a splitter cable (i.e. the connections would be the same). It is an industry standard way to daisy chain amps and I have seen a bank of 10 amps connected this way in a club. The strength of the signal does reduce a bit the more amps you daisy chain together but not normally enough to worry about.

1) Therefore the options are to daisy chain the amps and use one to power the subs and one to power the tops. The downside will be a slight loss of power sending full range signals when full range aren't needed and the tops will be duplicating some of the frequencies produced by the bass bins.

2) Using the one 1200w amp to power all four using the high pass to to the tops from the bass bins. Downside is the Celestions will probably have a higher SPL than the Carlsbro Bass Bins and it may sound a bit toppy and you won't get the extra benefit of using both amps

Both the above options would probably benefit from a good GEQ

3) Use a crossover to split the signal before it reaches the amps which would be the best option. The Behringher CX2310 would be a worth while investment at around £70.

[Excalibur]

If an amp has two inputs such as XLR and TRS jack (or phono), they are connected internally in parallel. Using one as input and one as output is much the same as using a splitter cable (i.e. the connections would be the same). It is an industry standard way to daisy chain amps and I have seen a bank of 10 amps connected this way in a club. The strength of the signal does reduce a bit the more amps you daisy chain together but not normally enough to worry about.

1) Therefore the options are to daisy chain the amps and use one to power the subs and one to power the tops. The downside will be a slight loss of power sending full range signals when full range aren't needed and the tops will be duplicating some of the frequencies produced by the bass bins.

2) Using the one 1200w amp to power all four using the high pass to to the tops from the bass bins. Downside is the Celestions will probably have a higher SPL than the Carlsbro Bass Bins and it may sound a bit toppy and you won't get the extra benefit of using both amps

Both the above options would probably benefit from a good GEQ

3) Use a crossover to split the signal before it reaches the amps which would be the best option. The Behringher CX2310 would be a worth while investment at around £70.

Thank you for that, Tony. I think we agree on 99% of this. I will defer to you on daisy chaining this way, as it's not a way I have done it. Still reckon best by far is to get a crossover. Think they all seem to be £70.

[Tony Scott]

If an amp has two inputs such as XLR and TRS jack (or phono), they are connected internally in parallel. Using one as input and one as output is much the same as using a splitter cable (i.e. the connections would be the same). It is an industry standard way to daisy chain amps and I have seen a bank of 10 amps connected this way in a club. The strength of the signal does reduce a bit the more amps you daisy chain together but not normally enough to worry about.

1) Therefore the options are to daisy chain the amps and use one to power the subs and one to power the tops. The downside will be a slight loss of power sending full range signals when full range aren't needed and the tops will be duplicating some of the frequencies produced by the bass bins.

2) Using the one 1200w amp to power all four using the high pass to to the tops from the bass bins. Downside is the Celestions will probably have a higher SPL than the Carlsbro Bass Bins and it may sound a bit toppy and you won't get the extra benefit of using both amps

Both the above options would probably benefit from a good GEQ

3) Use a crossover to split the signal before it reaches the amps which would be the best option. The Behringher CX2310 would be a worth while investment at around £70.


Agree totaly on the daisy chaining and the X-over suggestions. I have a
CX2310 and a CX3400 and can highly recommend either. 24db slope, very musical and great value for money.

[spin mobile disco]

Actually you will find an amp provides the same amount of power whatever you do with the volume pots. Reason being the volume pots on an amp only control the input stage of the signal the amps power normally about 40x the input stage remains constant. This is attenuated by the input signal being raised. And when the input signal X amp power reaches maximum that is when clipping would occure.
That is what the manafacturer handbook for a crown amplifier says and also as stated on my old peavey handbook.

[Tony Scott]

Actually you will find an amp provides the same amount of power whatever you do with the volume pots. Reason being the volume pots on an amp only control the input stage of the signal the amps power normally about 40x the input stage remains constant. This is attenuated by the input signal being raised. And when the input signal X amp power reaches maximum that is when clipping would occure.
That is what the manafacturer handbook for a crown amplifier says and also as stated on my old peavey handbook.

Yes I agree the potential for maximum power is always present at the output stage but unless it is given a voltage from the input by turning up the pots the semicoductors will not start conducting and will therefore not produce any power output.

Input clipping. A clipped input signal will only damage a speaker if it causes an amplifier to produce a power that would exceed the drivers thermal, electrical or mechanical limits. By turning down the pots you are limiting this signal, clipped or otherwise, which in turn limits the power to the output stage & speaker.
A clipped squarewave signal will not damage a speaker unless that signal has sufficient power.

Again I state turning down the pots (volume controls) DOES limit the power being fed to the speakers, it's simple electronics!

The only time I could forsee a problem in running an amp that is too big for the speakers is if the amp DC'd or developed a fault that would send the full signal to the output stage & all of the overpowered amp's power to the speakers. This would probably kill them. :D :)