Hi,
I'm currently planning a 3 (eventually 4) way set up.
I have a Behringer iNuke NU4 6000 with 4 channels and I'm planning on the following:
-Channel 1 & 2: Bridged @8 Ohms for 1500W to drive 2 18" subwoofers (parallel/series wired to stay at 8 Ohms, each with 700W RMS).
-Channel 3: 860W @ 4 Ohms to drive 2 12" mids parallel wired (400 RMS each).
-Channel 4: 440W @ 8 Ohms to drive 1 Compression driver (80W RMS).
I'm new to all of this and was wondering if it's okay to have one same amp with channels with different impedance each and outputting such different power. Or if you see any problem with this proposed setup or it there is anything else I should pay attention to.
Thanks!
I'm currently planning a 3 (eventually 4) way set up.
I have a Behringer iNuke NU4 6000 with 4 channels and I'm planning on the following:
-Channel 1 & 2: Bridged @8 Ohms for 1500W to drive 2 18" subwoofers (parallel/series wired to stay at 8 Ohms, each with 700W RMS).
-Channel 3: 860W @ 4 Ohms to drive 2 12" mids parallel wired (400 RMS each).
-Channel 4: 440W @ 8 Ohms to drive 1 Compression driver (80W RMS).
I'm new to all of this and was wondering if it's okay to have one same amp with channels with different impedance each and outputting such different power. Or if you see any problem with this proposed setup or it there is anything else I should pay attention to.
Thanks!
yes, you will blow everything to pieces.
No such a thing.
* drive each woofer with its own amp channel, forget bridging.
* drive each mid with its own amp channel.
* drive compression drivers with *another* amp. 60/120W RMS will do.
* be very careful with electronic crossover setup and very very careful on how you set up each channel limiters, specially for the horn drivers, or they will not survive the first cymbal crash.
Why? Technically his proposal is possible, although i would suggest running the 18" woofers without bridging, one channel each.
Semorales, two drivers can only be connected in series OR parallel. Series/parallel connection is only possible with more drivers, usually four. The trick is to first make two pairs in series connection, and then connect these two pairs in parallel.
Semorales, two drivers can only be connected in series OR parallel. Series/parallel connection is only possible with more drivers, usually four. The trick is to first make two pairs in series connection, and then connect these two pairs in parallel.
Thanks for the replies!
So why is bridging not recommended?
Do you mean avoid bridging in general or for this specific setup?
It's the only way I can think of of getting enough power for the subwoofers. Each channel has only got 440W @ 8 Ohms. And each subwoofer is 700W RMS.
Knowing I can't do parallel/series for just 2 drivers then I'd have to have Ch1+Ch2 doing 1600W @ 8 Ohm for 1 subwoofer, and Ch3+Ch4 for the other.
Or am I missing something? is there a way to lower an individual driver's impedance?
JMFahey, why do you recommend having each 12" driver on a different channel? Is parallel wiring to reduce to 4 Ohm not recommended? or you think 860W is too low for the two 12"? I want to understand the reason.
Also, why do you say it would all blow up? what would be the specific problem?
From your answers I assume there's no problem with having some channels with 4 Ohms and others with 8 Ohms, is that correct?
Looks like I will be having to get another amp.
So why is bridging not recommended?
Do you mean avoid bridging in general or for this specific setup?
It's the only way I can think of of getting enough power for the subwoofers. Each channel has only got 440W @ 8 Ohms. And each subwoofer is 700W RMS.
Knowing I can't do parallel/series for just 2 drivers then I'd have to have Ch1+Ch2 doing 1600W @ 8 Ohm for 1 subwoofer, and Ch3+Ch4 for the other.
Or am I missing something? is there a way to lower an individual driver's impedance?
JMFahey, why do you recommend having each 12" driver on a different channel? Is parallel wiring to reduce to 4 Ohm not recommended? or you think 860W is too low for the two 12"? I want to understand the reason.
Also, why do you say it would all blow up? what would be the specific problem?
From your answers I assume there's no problem with having some channels with 4 Ohms and others with 8 Ohms, is that correct?
Looks like I will be having to get another amp.
You loose 3 dB of final output power. The behringer is not rated for 2 ohm per channel (bridging two channels into 4 ohms is 2 ohm load per channel).
you will be fine with 400 watts. If you really need the last three dB, you should think about eventually getting another amp. 2 x 400 watts gives you about 30 dB additional output compared to 1 W, check your 18" woofers sensitivity and do the math. You will easily get above 120 dB, probably 125ish if your woofers are not crap.
you will be fine with 400 watts. If you really need the last three dB, you should think about eventually getting another amp. 2 x 400 watts gives you about 30 dB additional output compared to 1 W, check your 18" woofers sensitivity and do the math. You will easily get above 120 dB, probably 125ish if your woofers are not crap.
I don't know where you read this nonsense.
A pair of bridged amplifiers delivers exactly the same power as the pair of amplifier before they were bridged.
i.e. a bridged amp delivers twice the power into twice the impedance compared to the single amplifier.
Two 8ohms capable amplifiers delivering 100W each will when bridged deliver 200W into 16ohms.
If you have two 8ohms speakers you need to connect them in series to create a 16ohms load. The bridged amplifier will deliver twice the power into this combined load.
But the two amplifiers driving each 8ohms load will deliver EXACTLY the same power into the two separate speakers.
Now let's look at it a different way:
take your two 8ohms speakers and connect them in parallel. That creates a 4ohms load.
Take two amplifier and bridge them to drive that 4ohms combined load. Each amplifier of the bridged topology needs to be able to drive half the equivalent impedance. i.e. you need two 2ohms capable amplifiers to drive the 4ohms combined load when you bridge the two power amplifiers.
Do you have two 2ohms capable Power Amplfiers?
And finally, two separate amplifiers each dedicated to a single driver used in a PA set set up, leave the paying audience hearing something they paid for if you get ONE amp, or speaker failure.
Bridging two amplifiers to drive into two speakers means a riot if any one component fails !!!
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Again, thanks for replying,
I think the one I have does have 2 Ohm per channel, according to the user manual:
4-Channel
2 Ohm per channel 4x1600W
4 Ohm per channel 4x860W
8 Ohm per channel 4x440W
Bridge connection
4 Ohm per bridged pair 2x3000W
8 Ohm per bridged pair 2x1600W
As you've pointed out I can't use a bridged pair of channels @8 ohm for 1600W for 2 speakers, as there's no way to have 2 8 ohm drivers wired to stay at 8 ohms (it would be either 4 ohm parallel or 16 ohm series).
So your suggestion is using 1 channel for each subwoofer. This will output 400W @8 ohm, which means around 125dB as the drivers sensitivity is 98. This leaves me 2 channels for other uses and some unused driver potential.
Assuming I wanna use the full 700W potential the only other option with this amp and drivers is to bridge each pair of channels to 1600W @ 8 ohm. This would let me go up to the 700W RMS reaching 127dB. So a pair of channels for each driver. No unused channels but full driver potential used.
Finally, if I understand the user guide, each channel does have 2 ohm, so bridged pair can work at 4 ohm. So I could parallel wire the 2 drivers, being total 1400W @4 ohms.
And the bridged pair of channels @ 4 ohm could deliver 3000W, plenty of headroom for both drivers. This leaves the 2 other channels unused.
So, this last option looks ideal to me: full use of the drivers' potential and 2 spare channels. Is this somehow not desirable? does bridging bring any disadvantage or is riskier someway? Is working with 4 ohms riskier as it approaches the lower limit of the amp capabilities?
I think the one I have does have 2 Ohm per channel, according to the user manual:
4-Channel
2 Ohm per channel 4x1600W
4 Ohm per channel 4x860W
8 Ohm per channel 4x440W
Bridge connection
4 Ohm per bridged pair 2x3000W
8 Ohm per bridged pair 2x1600W
As you've pointed out I can't use a bridged pair of channels @8 ohm for 1600W for 2 speakers, as there's no way to have 2 8 ohm drivers wired to stay at 8 ohms (it would be either 4 ohm parallel or 16 ohm series).
So your suggestion is using 1 channel for each subwoofer. This will output 400W @8 ohm, which means around 125dB as the drivers sensitivity is 98. This leaves me 2 channels for other uses and some unused driver potential.
Assuming I wanna use the full 700W potential the only other option with this amp and drivers is to bridge each pair of channels to 1600W @ 8 ohm. This would let me go up to the 700W RMS reaching 127dB. So a pair of channels for each driver. No unused channels but full driver potential used.
Finally, if I understand the user guide, each channel does have 2 ohm, so bridged pair can work at 4 ohm. So I could parallel wire the 2 drivers, being total 1400W @4 ohms.
And the bridged pair of channels @ 4 ohm could deliver 3000W, plenty of headroom for both drivers. This leaves the 2 other channels unused.
So, this last option looks ideal to me: full use of the drivers' potential and 2 spare channels. Is this somehow not desirable? does bridging bring any disadvantage or is riskier someway? Is working with 4 ohms riskier as it approaches the lower limit of the amp capabilities?
Sorry i didnt check the actual rating of your amplifier.
Please do note, that you should be able to bridge only one pair of the inuke, while having the other two channels in normal mono mode.
Mono bridging for bass/sub bass is very demanding on the amplifier, and the inukes are made to a low price point. bridging two channels into sub and running it very hard will likely shorten the amplifiers life. But since the manufacturer has specified 4 ohm bridge, it should work. Just experiment and see what works best for you. Try one 18 per channel 8 ohm first, then 4 ohm parallel on one bridged channel pair. I would stick to 1 driver per channel if it gives enough output.
One thing about the impedance ratings: The impedance of the load determines how much electrical power the amplifier has to output. U/R=I, so the amplifier has to be able to deliver enough current for a given voltage. The lower the impedance, the more current. More current means more heat and stress on the semiconductors.
Please do note, that you should be able to bridge only one pair of the inuke, while having the other two channels in normal mono mode.
Mono bridging for bass/sub bass is very demanding on the amplifier, and the inukes are made to a low price point. bridging two channels into sub and running it very hard will likely shorten the amplifiers life. But since the manufacturer has specified 4 ohm bridge, it should work. Just experiment and see what works best for you. Try one 18 per channel 8 ohm first, then 4 ohm parallel on one bridged channel pair. I would stick to 1 driver per channel if it gives enough output.
One thing about the impedance ratings: The impedance of the load determines how much electrical power the amplifier has to output. U/R=I, so the amplifier has to be able to deliver enough current for a given voltage. The lower the impedance, the more current. More current means more heat and stress on the semiconductors.
Right, some misinformation here so lets see what we can do...
The NU4-6000 is basically the un-bridged version of the NU6000. Here's a bench test: Behringer inuke NU6000 vs KAM KXD7200 bench tested - Speakerplans.com Forums - Page 1
The NU4-6000 will do around 300w/ch into 8ohm, 600w/ch into 4ohm and 1000w/ch into 2ohm, all channels driven. The NU6000, being four of those channels bridged down to two, will do 1200w/ch @8ohm and around 2000w/ch into 4ohm, both channels driven.
If you put a 4ohm load across CHs1&2 bridged, it'll be fine. It's rated for (and the bench test above shows) running 4ohm on each side when bridged. That's all channels of the NU4-6000 running into 2ohm.
If you put the 18"s across ch1&2 (bridged) and then run the last two channels in stereo with 4ohm and 8ohm loads, the amplifier is actually having a fairly easy time.
I'd expect 2KW for the subs, 600w for the mids and 300w for the highs.
Chris
The NU4-6000 is basically the un-bridged version of the NU6000. Here's a bench test: Behringer inuke NU6000 vs KAM KXD7200 bench tested - Speakerplans.com Forums - Page 1
The NU4-6000 will do around 300w/ch into 8ohm, 600w/ch into 4ohm and 1000w/ch into 2ohm, all channels driven. The NU6000, being four of those channels bridged down to two, will do 1200w/ch @8ohm and around 2000w/ch into 4ohm, both channels driven.
If you put a 4ohm load across CHs1&2 bridged, it'll be fine. It's rated for (and the bench test above shows) running 4ohm on each side when bridged. That's all channels of the NU4-6000 running into 2ohm.
If you put the 18"s across ch1&2 (bridged) and then run the last two channels in stereo with 4ohm and 8ohm loads, the amplifier is actually having a fairly easy time.
I'd expect 2KW for the subs, 600w for the mids and 300w for the highs.
Chris
Thanks for the replies, they've been of great help.
Now that we've cleared that up, 2 more questions about how to actually execute this.
1) Can any pair of drivers be parallel wired to work at 4 ohms? Does the "Re" thiele-small parameter has anything to do with this?
2) The amp has 3 modes for each pair of channels: Stereo, Mono, Bridged. As I understand them based on the diagram on page 7 of the manual (https://media.music-group.com/media/PLM/data/docs/P0B1R/NU4-6000_P0B1R_QSG_WW.pdf):
Stereo: Each channel works independently. 2 inputs, 2 outputs.
Mono: Takes 1 input and sends it through 2 outputs.
Bridged: Takes 1 input, using the power of 2 channels and sends 1 output.
So according to what we've discussed in this thread if I use the mono setting, I'll be using Bob's advice: sending same signal to each driver but the driver's impedance stays at 8 ohm. So each channel still works independently, it just saves me the step of having 2 xlrs with the same input for bass (which I would have to have if using stereo mode).
Does it work that way?
Or using mono means that inside the amp a parallel connection is taking place and the impedance goes down to 4 ohm or some other thing? (i don't know if this is even possible, I would think not?)
Sorry for asking so much stuff, but I wanna double check as I'm new to this and can't really afford damaging any of this equipment.
Now that we've cleared that up, 2 more questions about how to actually execute this.
1) Can any pair of drivers be parallel wired to work at 4 ohms? Does the "Re" thiele-small parameter has anything to do with this?
2) The amp has 3 modes for each pair of channels: Stereo, Mono, Bridged. As I understand them based on the diagram on page 7 of the manual (https://media.music-group.com/media/PLM/data/docs/P0B1R/NU4-6000_P0B1R_QSG_WW.pdf):
Stereo: Each channel works independently. 2 inputs, 2 outputs.
Mono: Takes 1 input and sends it through 2 outputs.
Bridged: Takes 1 input, using the power of 2 channels and sends 1 output.
So according to what we've discussed in this thread if I use the mono setting, I'll be using Bob's advice: sending same signal to each driver but the driver's impedance stays at 8 ohm. So each channel still works independently, it just saves me the step of having 2 xlrs with the same input for bass (which I would have to have if using stereo mode).
Does it work that way?
Or using mono means that inside the amp a parallel connection is taking place and the impedance goes down to 4 ohm or some other thing? (i don't know if this is even possible, I would think not?)
Sorry for asking so much stuff, but I wanna double check as I'm new to this and can't really afford damaging any of this equipment.
You're correct about the stereo/mono/bridge settings. I'd refer to the "mono" setting as "parallel", since bridged output is technically mono.
I'd recommend bridging the first two channels and putting the subs on there. If the driver's nominal impedance is 8ohm, putting them in parallel will be fine. You'll get around 1000w per 18", which is a useful increase over the 300w per 18" you'd get by using the channels in parallel. If the drivers can handle it, you'll notice the increase in headroom.
Bridged amplifier: both channels are working to make one output. One amplifier is driven out-of-phase with the other amplifier. When you take the signal across the two outputs, you've got twice the voltage swing, and 4x the power so long as the amplifiers can deliver that. Each one is effectively working into half the load impedance. So, if your amplifier is rated for 2ohm stereo use, it'll only work for 4ohm bridged since each side is still seeing 2ohm.
Parallel: both channels are putting out the same signal. Some amplifiers will let you connect the two outputs together to drive very low impedances - the old Macrotechs could drive down to 1ohm this way. I wouldn't recommend connecting the outputs of the iNuke together. For your purposes, it just means both channels will do the same thing.
Stereo: the amplifier is working as two totally independent amplifiers that happen to be in the same box.
Chris
I'd recommend bridging the first two channels and putting the subs on there. If the driver's nominal impedance is 8ohm, putting them in parallel will be fine. You'll get around 1000w per 18", which is a useful increase over the 300w per 18" you'd get by using the channels in parallel. If the drivers can handle it, you'll notice the increase in headroom.
Bridged amplifier: both channels are working to make one output. One amplifier is driven out-of-phase with the other amplifier. When you take the signal across the two outputs, you've got twice the voltage swing, and 4x the power so long as the amplifiers can deliver that. Each one is effectively working into half the load impedance. So, if your amplifier is rated for 2ohm stereo use, it'll only work for 4ohm bridged since each side is still seeing 2ohm.
Parallel: both channels are putting out the same signal. Some amplifiers will let you connect the two outputs together to drive very low impedances - the old Macrotechs could drive down to 1ohm this way. I wouldn't recommend connecting the outputs of the iNuke together. For your purposes, it just means both channels will do the same thing.
Stereo: the amplifier is working as two totally independent amplifiers that happen to be in the same box.
Chris
I don't think Chris' interpretation of "mono" is correct.
Sem has stated
Sem has stated
This does not mention paralleling and I interpret that as two independent channels. Each is rated for 2ohms duty. Each channel can coast along driving separate 8ohms speakers. If at a later date one acqures extra 8ohms speakers, then one can parallel the 8ohms to give an effective 4ohms load. Each channel can easily drive this combined 4ohms load. i.e. two 2ohms rated channels in "mono" mode can drive two sets of paralleled 8ohms speakers (four speakers on two channels).
Chris explained everything perfectly, and since he has practical experience with your particular inuke model, i retract my recommendation to use parallel mono instead of bridge mode. just a little bit more about impedance:
I think you have understood the concepts already quite well. The most important thing you have to keep in mind is that the individual loudspeakers NEVER "change" or "lower" their own, proper impedance. An 8 ohm speaker is a 8 ohm speaker, the electrical parameters dont change when you connect a loudspeaker in series or parallel connection. You are creating a different circuit, and since ohms law applies to this circuit, the load impedance that the amplifier has to work with, is different. The individual components of the circuit have still the same properties.
I think you have understood the concepts already quite well. The most important thing you have to keep in mind is that the individual loudspeakers NEVER "change" or "lower" their own, proper impedance. An 8 ohm speaker is a 8 ohm speaker, the electrical parameters dont change when you connect a loudspeaker in series or parallel connection. You are creating a different circuit, and since ohms law applies to this circuit, the load impedance that the amplifier has to work with, is different. The individual components of the circuit have still the same properties.
The "mono" switch on the iNukes effectively connects the channel B input to the channel A input, except it's after the gain control. Both sides of the amplifier will output the same signals. I use that switch when I want an NU6000 to run all my subs but I don't want to run 2x XLR cables to do it.
Old iron amplifiers that didn't mind having their outputs connected together would be able to drive a 1ohm load (assuming each can do 2ohm) when the "parallel mono" setting is activated. I expect the iNukes would not enjoy having their outputs connected together, so I'd only recommend using it in cases similar to mine, where you want to power a few of the same cabinets.
Chris
That´s why I suggested a very conservative and reliable connection and setup.
This said with due respect: beginners always try to "use up to the last watt" .... while that´s not the point, the system must be balanced in all its components.
I trust your woofers standing 300/400 W RMS for long hours, maybe same for midrange speakers, definitely NOT the high frequency drivers, that´s why I suggested an extra, lower power amp for them, and you will *definitely* need to properly set up limiters on all of them.
Bridging amps to pull up to the last watt will probably murder the woofers
I *regularly* repair speakers with voice coils so burnt that there is a hole in the fiberglass former you can put a finger through, molten twisted deformed Kapton formers, burnt black carbon scales covered VC wire which I have to fish from inside the gap, the works.
In a nutshell: modern Class D technology has put in the hands of users amplifiers with 5X the power of old Class AB/G/H/F ones, 1/5 the weight and 1/2 the price, but speaker technology has NOT advanced that much, by any means, so I see everywhere (except in the hands of experienced Pros) people *murdering* their speakers.
So to wrap it up, when using "mono" mode on this amp, each channel will output around 300W @ 8 ohm, NOT 600W @ 4 ohm. Right?
I'm a bit confused then as to why it's called a "parallel" setting in other amps, as Chris has mentioned. It has nothing to do with driver parallel wiring then?
I got a bit lost here, what do you mean you could connect the 2 outputs together. How would the wiring be done? Not that I wanna try it, but I'm curious as to what that means.
JMFahey; said:
JM, thanks again for the advice. From what I've read I understand the 2 main driver damage causes are:
-Overheating from to much power.
-Over excursion over too low frequencies.
I'll be taking your advice on getting a weaker amp for the compression driver. But I still don't understand why you think the mids or the subwoofers are in such great risk.
2 channels bridged @ 4 ohm will output around 1,8kW for 2 drivers rated 1,5kW RMS combined. Seeing that people usually recommend having anywhere from 1,5x to 2x power on the amp as the RMS of the driver, 150W headroom per driver is well bellow that recommendation. I'd think it's pretty conservative isn't it?
The same for the mids, powering 2x12" rated 800W RMS with a 600W @ 4 ohm channel, seems pretty conservative as well, doesn't it?
On to the limiters subject. I hadn't really thought about it. I was planning on hooking DJ mixer to active crossover to amps.
I just thought of not letting the clip indicator (0dBFS Limit indicator per channel according to manual) light up frequently. Though I have a big question here as I read that the input signal from the mixer could come clipped into the amp and in that case the amps clip indicator wouldn't light up. Anyone any advise on how to avoid this?
Please let me know what you think, really appreciate all the input I've been getting here!
in the "mono" mode there is some disagreement on what your amplifier is capable of doing.
NOT connecting the two output in parallel is safer than connecting them together. Keep the outputs separate.
One speaker or speaker set on one output and a separate speaker or speaker set on the other output.
Generally speaking, amps that are 'stable' into 2Ω will be fine running 4Ω.
The mean time before failure (MTBF) on most amps into 2Ω is very, very short.
I own two Behringer iNuke NU4-6000. I use them for stereo mids and HF, and use a 2Ω rated Crest that weights 70 LBS for low-end duty (that I run at 4Ω).
http://i56.photobucket.com/albums/g196/dkleitsch/COE08-3.jpg
I had to run 2Ω in an emergency situation, an amp-rack had the mid and HF amp puking smoke due the the crossover taking a hike. I had another crossover and enough amps, but the original rack had hi-fi amps and cables, and the Crest stack had to be driven in mono (no one noticed) due to lack of proper cabling.
The mean time before failure (MTBF) on most amps into 2Ω is very, very short.
I own two Behringer iNuke NU4-6000. I use them for stereo mids and HF, and use a 2Ω rated Crest that weights 70 LBS for low-end duty (that I run at 4Ω).
http://i56.photobucket.com/albums/g196/dkleitsch/COE08-3.jpg
I had to run 2Ω in an emergency situation, an amp-rack had the mid and HF amp puking smoke due the the crossover taking a hike. I had another crossover and enough amps, but the original rack had hi-fi amps and cables, and the Crest stack had to be driven in mono (no one noticed) due to lack of proper cabling.
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