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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: chris broadway on March 26, 2014, 09:42:38 AM
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I'm assuming someone with 'electrical' knowledge will be able to answer this question. I have three amps. One goes to a single house speaker, one goes to two house speakers (because of existing wiring we have these daisy chained), and one going to a monitor. I have always noticed that the amp with the daisy chained speakers showed a higer level than the other house speaker. Occasionally it would even clip while the other amp level was very low. This past weekend I wanted to daisy chain a monitor off the one monitor running off a dedicated amp. Immediately I noticed this amp now was clipping. I unplugged the daisy chained monitor and the issue went away. This leads me to believe that a daisy chained speaker has more draw on the amp and doubles the load and level. Can anyone with an electrical background explain this to me?
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What model(s) are the amp(s) in question? What models are the speakers in question?
Without knowing the specs of either we can't really give you a definitive answer.
However, what you may be doing by "daisy chaining" the speakers is putting a load on the amp outside of what it can handle. While it's common practice to do this (the daisy chaining, not overloading) it's very important to make sure that the resulting final load is within your amp's specs. If your amp is only rated to 4 ohms and you put a 2ohm load to it, it won't be happy and could cause damage to your rig. Also, using the existing wiring might be causing you issues as well if you haven't verified that there's nothing else on the circuit.
Some more details on your equipment will go a long way, so start there.
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Crown CTS 600 amps
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Forgot to add the house speakers are EV-122S94. I cannot remember the monitor model.
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It would help to know the models of the amps, and speakers that you are using. Or at least the resistance (ohm rating) of each speaker that is in the chain. Also are all of the amps being fed the same signal or are they from different feeds?
Adding speakers reduces the resistance on the amp witch does let more power through on most amp models. If you are looking for a lengthy technical description look up Ohms law. The short description is that if you connect two speakers that are 8 ohms to one amp channel your total resistance is 4 ohms. Two at 4 ohms would be 2 ohms. The math gets a little more complex with 3 speakers or two speakers of different resistance.
HOWEVER
The lights on the front of the amps usually represent the input signal coming into the amp and as far as I know are not affected but the load that you are putting on the output.
Again if you let us in on the make and model of the equipment you are using it might shed some light on the situation.
Luke
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Forgot to add the house speakers are EV-122S94. I cannot remember the monitor model.
The EV speakers are 8 ohms, and look like they want between 500 and 1000 watts to run at peak performance. The CTS600 is not getting near that. When you put 3 together you are running at a 2.6 ohm load witch in the case of this crown amp starts to decrease its output power. So it is likely that you are turning the system up to compensate.
I would recommend more power if you can afford to do it.
as far as the lights on the front of the amp I am not that experienced with these particular crown amps and how their meters read so hopefully someone else here may be able to shed some light on the situation.
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It would help to know the models of the amps, and speakers that you are using. Or at least the resistance (ohm rating) of each speaker that is in the chain. Also are all of the amps being fed the same signal or are they from different feeds?
Adding speakers reduces the resistance on the amp witch does let more power through on most amp models. If you are looking for a lengthy technical description look up Ohms law. The short description is that if you connect two speakers that are 8 ohms to one amp channel your total resistance is 4 ohms. Two at 4 ohms would be 2 ohms. The math gets a little more complex with 3 speakers or two speakers of different resistance.
HOWEVER
The lights on the front of the amps usually represent the input signal coming into the amp and as far as I know are not affected but the load that you are putting on the output.
Again if you let us in on the make and model of the equipment you are using it might shed some light on the situation.
Luke
So it looks like I need to learn 'ohms' and what they are. thanks for the ohms law reference. So without having looked at ohms law yet, here is my guess. If I have two amps set at the same output level, and one speaker plugged into each amp, theoretically I should get the same output and visually see this on the LED level indicator. Once I add a like speaker in a daisy chain fashion to one of the existing speakers, the resistance is less causing a higher output (hotter signal) from the amp? Is this a high level understanding for a lay person?
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The EV speakers are 8 ohms, and look like they want between 500 and 1000 watts to run at peak performance. The CTS600 is not getting near that. When you put 3 together you are running at a 2.6 ohm load witch in the case of this crown amp starts to decrease its output power. So it is likely that you are turning the system up to compensate.
I would recommend more power if you can afford to do it.
as far as the lights on the front of the amp I am not that experienced with these particular crown amps and how their meters read so hopefully someone else here may be able to shed some light on the situation.
Just plugging another speaker in should NOT, by itself, make the clip lights come on. Performance of the speaker/amp combination is another matter.
I'm suspecting a shorted speaker cable or a cable that is wired "funny."
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Just plugging another speaker in should NOT, by itself, make the clip lights come on. Performance of the speaker/amp combination is another matter.
I'm suspecting a shorted speaker cable or a cable that is wired "funny."
But this behavior was seen over two different amps and two different speakers. It could not be a cable or speaker issue.
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But this behavior was seen over two different amps and two different speakers. It could not be a cable or speaker issue.
Think again.
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Faulty wiring knows no bounds.
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But this behavior was seen over two different amps and two different speakers. It could not be a cable or speaker issue.
Most modern amps will indicate clip when current limiting (like from too heavy load impedance or wiring fault). While a wiring fault will usually cause audible artifacts.
JR
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Most modern amps will indicate clip when current limiting (like from too heavy load impedance or wiring fault). While a wiring fault will usually cause audible artifacts.
JR
Here is an example for my questions:
1) If I have two amps with one speaker plugged in each. Lets call the amp/speaker sets "A" and "B".
2) both amps are at the same output level and visual LED on the front and sound is good
3) And then I grab another speaker of the exact same type and daisy chain it to set "A"
4) SET "B" amp and speaker that have not changed are still the same while set "A" amp and speaker now visually clipping and I hear the 'overdrive sound'
5) I remove the extra speaker from set "A" and now daisy chain it to set "B"
6) set "A" is back to normal and set "B" now visually clips and I hear the overdrive sound
The problem followed the daisy chain over two diverse paths. How is this a cabling issue?
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Here is an example for my questions:
1) If I have two amps with one speaker plugged in each. Lets call the amp/speaker sets "A" and "B".
2) both amps are at the same output level and visual LED on the front and sound is good
3) And then I grab another speaker of the exact same type and daisy chain it to set "A"
4) SET "B" amp and speaker that have not changed are still the same while set "A" amp and speaker now visually clipping and I hear the 'overdrive sound'
5) I remove the extra speaker from set "A" and now daisy chain it to set "B"
6) set "A" is back to normal and set "B" now visually clips and I hear the overdrive sound
The problem followed the daisy chain over two diverse paths. How is this a cabling issue?
Since the cable appears to be the only thing common to both setups, one would highly suspect it to be faulty. Assuming that something can't be the problem without testing or proof sabotages the problem solving process.
So many times people have persisted in saying "it couldn't be XXX" only to come back after 5 pages of posts and say "It was XXX after all".
Check your cables.
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As Dick is saying Short in cable or short in patch panel.
On another note, Are you bridging these amps?
CTS 600's current limit 2 ohm st and 4 ohm bridge and are basicly useless at either of these tasks.
Wrong tool for the job.
Regards,
Nate
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Here is an example for my questions:
1) If I have two amps with one speaker plugged in each. Lets call the amp/speaker sets "A" and "B".
2) both amps are at the same output level and visual LED on the front and sound is good
3) And then I grab another speaker of the exact same type and daisy chain it to set "A"
4) SET "B" amp and speaker that have not changed are still the same while set "A" amp and speaker now visually clipping and I hear the 'overdrive sound'
5) I remove the extra speaker from set "A" and now daisy chain it to set "B"
6) set "A" is back to normal and set "B" now visually clips and I hear the overdrive sound
The problem followed the daisy chain over two diverse paths. How is this a cabling issue?
Did we determine loudspeaker impedance, and amp drive capability?
OK allow mw... Crown CTs600
300W @ 8 Ohm,
300W @ 4 ohm,
150W @ 2 ohm
Daisy chain is not a technical term. Can I ASSume you mean connected in "parallel", which would drop the speaker impedance in half, requiring 2x the current from the amp at same level setting?
As I already posted a wiring fault is usually more severe with the amp barely making any output at all, while they happen occasionally where there is only a partial short. A wiring fault "could" be in the same wire you use to attack the same extra speaker, while I consider that a low probability.
More likely scenario is simple amp current limiting from too much speaker load, while most amps can drive two speakers, that model Crown does not look happy with heavier loads.
In general when you load an amplifier with 4 ohms it will make roughly 2x the power that it would at 8 ohms. Your amp makes the same power at 4 ohms, so guess what? It is already current limiting at 4 ohms so paralleling two 8 ohm cabs makes the same 300W as one 8 ohm cab but now split between two boxes so 1/2 the original power per box. Adding a third cab would actually result in less total power out.
My advice is you need a lot more amp...
JR
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Since the cable appears to be the only thing common to both setups, one would highly suspect it to be faulty. Assuming that something can't be the problem without testing or proof sabotages the problem solving process.
So many times people have persisted in saying "it couldn't be XXX" only to come back after 5 pages of posts and say "It was XXX after all".
Check your cables.
I know I am the one seeking the answers and need to be receptive to all comments...but how many more times can I say there is no common cable? Read the original question in the original post. the example I gave was to try and 'decomplicate' the issue. These are two separate diverse paths with no common anything between the two.
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The EV speakers are 8 ohms, and look like they want between 500 and 1000 watts to run at peak performance.
Just to clarify, speakers do not "want" power, you deliver power into them and all the speaker power rating indicates is the maximum power you can safely put into them, not how much power it "wants". The power rating also has nothing to do with peak performance, only maximum output. If the speakers get as loud as you need them to be then the amp being rated less than the speaker power rating is irrelevant.
As to the Chris's issue, it may be important to note that they apparently have one amp driving one house speaker, one amp driving two daisy chained (assuming meaning parallel wired) house speakers and one amp driving one monitor. So all three amps seem to be operating in a single channel mode and thus likely bridged mode. In bridge mode the CTs is rated at 600W into 16 Ohms or 8 Ohms and 300W into 4 Ohms. So different numbers than JR presented but otherwise the same concept regarding it being related to current limiting.
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Just to clarify, speakers do not "want" power, you deliver power into them and all the speaker power rating indicates is the maximum power you can safely put into them, not how much power it "wants". The power rating also has nothing to do with peak performance, only maximum output. If the speakers get as loud as you need them to be then the amp being rated less than the speaker power rating is irrelevant.
As to the Chris's issue, it may be important to note that they apparently have one amp driving one house speaker, one amp driving two daisy chained (assuming meaning parallel wired) house speakers and one amp driving one monitor. So all three amps seem to be operating in a single channel mode and thus likely bridged mode. In bridge mode the CTs is rated at 600W into 16 Ohms or 8 Ohms and 300W into 4 Ohms. So different numbers than JR presented but otherwise the same concept regarding it being related to current limiting.
I think you and JR hit the nail on the head. thanks.
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Just to clarify, speakers do not "want" power, you deliver power into them and all the speaker power rating indicates is the maximum power you can safely put into them, not how much power it "wants". The power rating also has nothing to do with peak performance, only maximum output. If the speakers get as loud as you need them to be then the amp being rated less than the speaker power rating is irrelevant.
As to the Chris's issue, it may be important to note that they apparently have one amp driving one house speaker, one amp driving two daisy chained (assuming meaning parallel wired) house speakers and one amp driving one monitor. So all three amps seem to be operating in a single channel mode and thus likely bridged mode. In bridge mode the CTs is rated at 600W into 16 Ohms or 8 Ohms and 300W into 4 Ohms. So different numbers than JR presented but otherwise the same concept regarding it being related to current limiting.
I forgot to add...this is the line from JR I am going to follow up on "In general when you load an amplifier with 4 ohms it will make roughly 2x the power that it would at 8 ohms". If I understand this correctly, running parallel will decrease the impedance from 8 to 4 ohms which then makes the amp send twice as much power. this makes sense why I can have to amps one in parallel and one not, both set at the same output level, and the parallel one shows twice the output on the LED.
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I forgot to add...this is the line from JR I am going to follow up on "In general when you load an amplifier with 4 ohms it will make roughly 2x the power that it would at 8 ohms". If I understand this correctly, running parallel will decrease the impedance from 8 to 4 ohms which then makes the amp send twice as much power. this makes sense why I can have to amps one in parallel and one not, both set at the same output level, and the parallel one shows twice the output on the LED.
You are still not understanding how this all works. You do not "set the output level", rather, you set the input sensitivity. The amp ALWAYS puts out its rated power. The knobs or controls that you consider to "set the output" are simply there to tailor the input signal to the amp for optimum signal level.
And running an amp bridged does not change the impedance. The number of speakers and their rated ohmage determines the load that the amp sees. The specs for "stereo/bridged" loading are to designate what kind of load the amp can tolerate in each mode.
The fly in your ointment/flaw in your reasoning is a basic misunderstanding of how this stuff all works together. You assume a certain level of knowledge but don't really have it. Neither do I, for a lot of stuff. As such, your trouble-shooting is skewed and you end up shooting way off target.
I at least know enough to know what I don't know. Not trying to be hard on you, just realistic. I wish you all the luck in the world. May all your problems be this small.
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Just to clarify, speakers do not "want" power, you deliver power into them and all the speaker power rating indicates is the maximum power you can safely put into them, not how much power it "wants". The power rating also has nothing to do with peak performance, only maximum output. If the speakers get as loud as you need them to be then the amp being rated less than the speaker power rating is irrelevant.
As to the Chris's issue, it may be important to note that they apparently have one amp driving one house speaker, one amp driving two daisy chained (assuming meaning parallel wired) house speakers and one amp driving one monitor. So all three amps seem to be operating in a single channel mode and thus likely bridged mode. In bridge mode the CTs is rated at 600W into 16 Ohms or 8 Ohms and 300W into 4 Ohms. So different numbers than JR presented but otherwise the same concept regarding it being related to current limiting.
I took those numbers from Crown's website but didn't read down to the bridged numbers.
So yes 1x 8 ohm speaker bridged is 600 W, 2x8 ohm in parallel bridged is 300W total so not as loud. The OP would get more power from 2x 8 ohm speakers attached to the different channel outputs (not parallel). But still only 600W total.
Get a bigger amp.
JR
PS: JR said "in general when you load an amp with 4 ohms it makes 2x the power as 8 ohms", unless it is a Crown CTs600 which does not, because it is apparently current limited below 8 ohms .
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+1 on JR's last post. All amplifiers do not have the same characteristics at different loads, especially in bridged mode. IF the amps are in bridged mode it is not surprising at all that you are having these issues. And, as Dick pointed out, the knobs do not control the output, only the input, but the meters are (I suspect) indicative of the output.
You need different amps if you want to make any changes along the lines of what you are doing.