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Author Topic: Bridging Subwoofers?  (Read 17318 times)

Bob Leonard

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Re: Bridging Subwoofers?
« Reply #10 on: April 02, 2014, 02:38:48 pm »

Bob is right... You would not be running your system in stereo Subwoofers I mean) however you would simply just be using one Side of the amp and not both to power the subs... So you would have a free channel on the amp. You can still use the sub out on your crossover and use the other sub in parallel as stated above. You would just be driving one channel and not both bridged. Musicians friends offers a package to run one sub per side of the amp. Not for the amp to be used bridged. Did this answer your question?


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What I'm saying is don't bridge the amp and run one (1) sub from each channel.
 
The amp is only working as hard as it needs to in order to supply the required output. Running at a low impedance will work the amp harder, another reason I'm not in favor of bridging the amp.
 
If you feel the speakers will handle the output and you want to do the job right then buy an amp that will produce 800 watts per channel at 8 ohms. Just be aware the additional 400 watts is for headroom, not for driving your cabinets to destruction.
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Corey Scogin

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Re: Bridging Subwoofers?
« Reply #11 on: April 02, 2014, 03:20:27 pm »

I would rather have my subs overpowered than under powered. I have always heard what you mentioned about powering subs 1.5-2x their continuous power rating and that it is worse for your sub to be underpowered by a low amp because the amp is working harder than the speaker then. So you are saying I should be able to daisy chain them like my first post said and leave it in bridged mode? I mean everything should be ok as long as I don't clip right?

There is no problem with powering speakers with an amp that's rated for less than the speakers can handle.

The answer to both your questions is yes.

Also read what Bob Leonard writes and take heed.
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Justin Smith

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Re: Bridging Subwoofers?
« Reply #12 on: April 02, 2014, 03:29:19 pm »


What I'm saying is don't bridge the amp and run one (1) sub from each channel.
 
The amp is only working as hard as it needs to in order to supply the required output. Running at a low impedance will work the amp harder, another reason I'm not in favor of bridging the amp.
 
If you feel the speakers will handle the output and you want to do the job right then buy an amp that will produce 800 watts per channel at 8 ohms. Just be aware the additional 400 watts is for headroom, not for driving your cabinets to destruction.

Ok. Thank you. So follow that chart then basically? Connect one speaker to each channel and put it in parallel mode? That way I can use a mono input to the amp? Also, this would still be underpowering my subs right at 350 watts per channel?
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Brad Weber

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Re: Bridging Subwoofers?
« Reply #13 on: April 02, 2014, 04:50:39 pm »

I would rather have my subs overpowered than under powered. I have always heard what you mentioned about powering subs 1.5-2x their continuous power rating and that it is worse for your sub to be underpowered by a low amp because the amp is working harder than the speaker then. So you are saying I should be able to daisy chain them like my first post said and leave it in bridged mode? I mean everything should be ok as long as I don't clip right?
The whole point is to run the system within its capabilities and to not try to get more than it can give.  Running more power may move up the point at which you will exceed the system's capabilities but can do so at the tradeoff of perhaps paying a bigger penalty if you do exceed the system's capabilities.
 
Also don't get misled by wattage numbers, the difference between 350W and 650W per speaker is +2.7dB and thus likely related to a just noticeable increase in perceived volume.
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John Jackson

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Re: Bridging Subwoofers?
« Reply #14 on: April 02, 2014, 05:42:38 pm »

The Crown website advises power amp owners to choose amps that are rated at 2-4 times the continuous power rating of the speaker load. That is what I go by.

That means a speaker rated at 400W RMS/800W Program/1,600W Peak should have 800 - 1,600 watts of power available to each cabinet.

Based on this formula, I would recommend powering two speakers rated 350W RMS with a single bridged power amp that puts out between 1,600 and 3,200 watts peak power. This will give you 2-4 times the continuous power rating of the speaker which is within the Crown website specs.

Having more amplifier headroom vs. less will keep you from clipping your amps, which is the most-common cause of driver damage. When you drive an amplifier too hard it causes distortion and clipping, whereas a properly power speaker system will avoid distortion and clipping.

Sure, you can still blow up your speakers if you push them too hard even with plenty of amp headroom - but the chance of blowing up your drivers actually decreases with more power vs. underpowering. Treat it like a Corvette... you've got all the power you need, but you don't have to use it all! I'd rather hear and feel a solid kick drum in the subwoofers than a bunch of distortion and mud due to amp clipping in an underpowered sub.

http://www.crownaudio.com/how_much_power.htm

Quote from: CrownAudio.com
How much power can my speakers handle?

You can determine this by looking at the speaker's data sheet. Look for the Nominal Impedance spec. Typically it will be 2, 4, 8 or 16 ohms. Next, look for the loudspeaker specification called Continuous Power Handling or Continuous Power Rating. It might be called IEC rating or Power capacity.

If you can prevent the power amp from clipping (by using a limiter), use a power amp that supplies 2 to 4 times the speakers continuous power rating per channel. This allows 3 to 6 dB of headroom for peaks in the audio signal. Speakers are built to handle those short-term peaks. If you can't keep the power amp from clipping (say, you have no limiter and the system is overdriven or goes into feedback) the amplifier power should equal the speakers continuous power rating. That way the speaker won't be damaged if the amp clips by overdriving its input. In this case there is no headroom for peaks, so you'll have to drive the speaker at less than its full rated power if you want to avoid distortion.

If you are mainly doing light dance music or voice, we recommend that the amplifier power be 1.6 times the Continuous Power rating per channel. If you are doing heavy metal/grunge, try 2.5 times the Continuous Power rating per channel. The amplifier power must be rated for the impedance of the loudspeaker (2, 4, 8 or 16 ohms).

Here's an example. Suppose the impedance of your speaker is 4 ohms, and its Continuous Power Handling is 100 W. If you are playing light dance music, the amplifier's 4-ohm power should be 1.6 x 100 W or 160 W continuous per channel. To handle heavy metal/grunge, the amplifier's 4-ohm power should be 2.5 x 100 W or 250 W continuous per channel.

If you use much more power, you are likely to damage the speaker by forcing the speaker cone to its limits. If you use much less power, you'll probably turn up the amp until it clips, trying to make the speaker loud enough. Clipping can damage speakers due to overheating. So stay with 1.6 to 2.5 times the speaker's continuous power rating.

Hope this helps! I had to learn the hard way by toasting two subwoofer baskets due to underpowering/clipping them. Running a speaker with an amp that only puts out the continuous wattage rating of the speaker (or less) creates a virtual guarantee that you will clip your amps when trying to make the speaker loud enough.
« Last Edit: April 02, 2014, 06:15:20 pm by John Jackson »
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Justin Smith

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Re: Bridging Subwoofers?
« Reply #15 on: April 02, 2014, 06:48:21 pm »

The Crown website advises power amp owners to choose amps that are rated at 2-4 times the continuous power rating of the speaker load. That is what I go by.

That means a speaker rated at 400W RMS/800W Program/1,600W Peak should have 800 - 1,600 watts of power available to each cabinet.

Based on this formula, I would recommend powering two speakers rated 350W RMS with a single bridged power amp that puts out between 1,600 and 3,200 watts peak power. This will give you 2-4 times the continuous power rating of the speaker which is within the Crown website specs.

Having more amplifier headroom vs. less will keep you from clipping your amps, which is the most-common cause of driver damage. When you drive an amplifier too hard it causes distortion and clipping, whereas a properly power speaker system will avoid distortion and clipping.

Sure, you can still blow up your speakers if you push them too hard even with plenty of amp headroom - but the chance of blowing up your drivers actually decreases with more power vs. underpowering. Treat it like a Corvette... you've got all the power you need, but you don't have to use it all! I'd rather hear and feel a solid kick drum in the subwoofers than a bunch of distortion and mud due to amp clipping in an underpowered sub.

http://www.crownaudio.com/how_much_power.htm

Hope this helps! I had to learn the hard way by toasting two subwoofer baskets due to underpowering/clipping them. Running a speaker with an amp that only puts out the continuous wattage rating of the speaker (or less) creates a virtual guarantee that you will clip your amps when trying to make the speaker loud enough.

That is exactly what I always heard as well from different website and also YouTube videos and what not. That is why I am so confused that everyone is giving me different answers. Like you said, I would rather have more headroom on the amp side than the subwoofer side because you don't have to use all of the power. If I do end up damaging the subs from trying to use too much power, then I could buy another sub that is more powerful and most likely already have the amp that would power it so I wouldn't have to worry about getting another amp that is more powerful. Just a good way to look at it I guess lol. Thank you for the advice and information from the website!
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John Jackson

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Re: Bridging Subwoofers?
« Reply #16 on: April 02, 2014, 06:58:15 pm »

That is why I am so confused that everyone is giving me different answers.

Welcome to the world of live sound lol. I have found that the topic of how much amp wattage to use per speaker is the most controversial debate of all. Not sure why, but people get downright hostile and derogatory over it. Glad to put it to rest for you.  8)
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Bob Leonard

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Re: Bridging Subwoofers?
« Reply #17 on: April 02, 2014, 09:08:15 pm »

OK, let's be more accurate. My remarks have to do with you having a working, good sounding, safe system utilizing the hardware you own.

If your goal is to upgrade then the approach that I have preached for better than 40 years concerning power to the cabinets is two (2) times the long term power rating. This "rule of thumb" is what the industry practices and preaches. This is what JBL, EV, and most reputable manufacturers will recommend.

There are two ways to destroy your cabinets. The first is to over power the cabinets, and if you're going to use an amplifier rated 2,3,4 times the long term power rating you need to understand your speakers capabilities and insure the additional power is used as intended. Not to drive the cabinets another 3db louder, but to allow for additional power to meet the instantaneous short term needs of the program material.

If you need more output than what your cabinets will handle safely then you need to upgrade, end of subject.

The second way to destroy your cabinets and probably your amplifiers is to drive them into hard clip. clipping and amplifier can produce a minimum of two times the rated output voltages. I'm not going into detail on the subject because it's been covered here a thousand times. Just be aware that the little red light is there for a reason, and that reason is to tell you bad things are about to happen.

In the end the choice is yours. Either live with a few db lass output, or push your cabinets to their limit and trust you know enough about controlling sound to keep them from being destroyed.
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BOSTON STRONG........
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I did a gig for Otis Elevator once. Like every job, it had it's ups and downs.

Justin Smith

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Re: Bridging Subwoofers?
« Reply #18 on: April 02, 2014, 09:29:56 pm »

OK, let's be more accurate. My remarks have to do with you having a working, good sounding, safe system utilizing the hardware you own.

If your goal is to upgrade then the approach that I have preached for better than 40 years concerning power to the cabinets is two (2) times the long term power rating. This "rule of thumb" is what the industry practices and preaches. This is what JBL, EV, and most reputable manufacturers will recommend.

There are two ways to destroy your cabinets. The first is to over power the cabinets, and if you're going to use an amplifier rated 2,3,4 times the long term power rating you need to understand your speakers capabilities and insure the additional power is used as intended. Not to drive the cabinets another 3db louder, but to allow for additional power to meet the instantaneous short term needs of the program material.

If you need more output than what your cabinets will handle safely then you need to upgrade, end of subject.

The second way to destroy your cabinets and probably your amplifiers is to drive them into hard clip. clipping and amplifier can produce a minimum of two times the rated output voltages. I'm not going into detail on the subject because it's been covered here a thousand times. Just be aware that the little red light is there for a reason, and that reason is to tell you bad things are about to happen.

In the end the choice is yours. Either live with a few db lass output, or push your cabinets to their limit and trust you know enough about controlling sound to keep them from being destroyed.

Thank you for the advice and concern! I am not sure exactly what I will do yet. I guess I could try either way and see which works best for me and make sure their aren't any issues with whatever way I choose. However, the first step is to get the second sub which I have not done yet. So I have some time to think/try. But thanks again for the info!
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Rob Spence

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Re: Bridging Subwoofers?
« Reply #19 on: April 02, 2014, 09:51:45 pm »

Thank you for the advice and concern! I am not sure exactly what I will do yet. I guess I could try either way and see which works best for me and make sure their aren't any issues with whatever way I choose. However, the first step is to get the second sub which I have not done yet. So I have some time to think/try. But thanks again for the info!

Take the bass & most drums out of the PA.
You do not have "enough rig for the gig" to improve the bass & guitars and cymbals and snare. You need significant subs to deal with rock kick and bass.


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Re: Bridging Subwoofers?
« Reply #19 on: April 02, 2014, 09:51:45 pm »


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