Subwoofer linked ?

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ok Thanks. would i overload it if i had 2 500wspeakers and a 250w sub linked to a 1000w then ??

It's not just the wattage, it's the resistance. If your speakers are all 8ohms, (THEY VERY WELL MAY NOT BE, SO CHECK) and you connect 2 speakers in parallel, the resistance drops to 4ohms. Disregarding wattage, the lower the resistance, the more current an amp draws (and the more easily it blows up) which is why amps have a minimum resistance rating per channel. Make sure your amp is rated for 4ohms per channel before you connect them together like this. (it probably is, but always always double check)

Now, in regard to the other part of your question here, 3 speakers on 2 channels is not exactly a good idea. Firstly, you should be using a crossover with the sub on a separate channel. I'll assume you don't have a crossover, since it wasn't mentioned. Some amps have what's called 'tri-mode,' where you can bridge the sub between the 2 channels. Lacking a proper crossover, this is the only recommended way to hook it up.

Posting specific models always helps us help you better.
 
It wouldn't damage the amp. The amp is going to put out 1000w regardless if it is a 1w headphone speaker or 2000 watt sub. You will be slightly underpowering your speakers though which can be bad but 250 shouldn't make a huge difference, but your not going to get the full potential out of your speakers. If you want to get your moneys worth, I would get another amp just for the sub. 250 watters wont be to expensive, probably will find them though either 300w or 500w.



*Very sorry if I am incorrect! Someone may correct me.
 
Isn't the XTR-400 a powered subwoofer that was part of a packaged sub and satellite system? I believe that the crossover and amplifiers for both the sub and the satellites are built into the subwoofer, you would run line level to the XTR-400 and then connect the other speakers to the amplifier built into it, you would not use a separate amplifier. If you connect the XTR-400 inputs to another amplifier you will probably damage both.

Depending on the existing speakers and amp and what you are trying to do, I'm not sure that trying to incorporate an XTR-400 makes much sense.
 
It wouldn't damage the amp. The amp is going to put out 1000w regardless if it is a 1w headphone speaker or 2000 watt sub. You will be slightly underpowering your speakers though which can be bad but 250 shouldn't make a huge difference, but your not going to get the full potential out of your speakers. If you want to get your moneys worth, I would get another amp just for the sub. 250 watters wont be to expensive, probably will find them though either 300 or 500.



*Very sorry if I am incorrect! Someone may correct me.

PLEASE PLEASE IGNORE THIS. not because it's wrong, but because it's dangerous.

You should never underpower your speakers, just like you should never overpower your speakers. The closer to max you push an amp, the more noise you're sending out, which can damage speakers. Your amp's capacity should be greater than your speaker RMS rating, but lower than your speaker's max rating as a general rule of thumb.

The second part of your statement is the complete ignorance of impedence. If you connect too many speakers to your amp, no matter what the wattage, you can blow it up.

Have a looksee here.
 
Thanks for the replies and on my amp there are 3 channels 2 for each speaker and a bridge ? would i be able to put the amp on a bridge ?

also the XTR-400 is a powered amp but i brought the sub not the amp with it lol.

Thanks
 
Very sorry, I think I meant to add not to push the amp though.

I have a 800 watt amp running two 1200 watt cabs (Personell) but the amp is never at its max.
I was surprised that 400~ watts was enough to move the cones.

(Note this is a junky system I got for nearly free and used in my home)
 
what would happen if i had 2 500w speakers on 2 seprates and i had the sub on bridge ??

heres my amp by the way : Power Amp 1600 - Free Delivery : Lights & Sounds : Maplin
No, your amp does not support tri-mode. You can use either stereo or bridged mono, not both simultaneously.

I'm still missing how you have a powered subwoofer that isn't powered...

Now theoretically you could wire it so that your speakers are wired normally, and your sub is using a + off of one channel and a - off of another channel, which is how tri-mode works, but I wouldn't recommend playing with the wires like that unless you know what you're doing.

Very sorry, I think I meant to add not to push the amp though.
Again, read the site on impedance. It doesn't matter how hard you push the amp.

I have a 800 watt amp running two 1200 watt cabs (Personell) but the amp is never at its max.
I was surprised that 400~ watts was enough to move the cones.

And here we see the difference between what you CAN do and what you SHOULD do. My boss (IT boss, not audio boss) hooked up a powered yamaha board a few days ago with a bunch of speakers, and it was running at 2ohms terribly underpowered while only rated for 4ohms and roasting outside in 90 degree sun. It worked fine, but that doesn't mean it's good, safe, or recommended.

Sure you can run an 800W amp with 1200W speakers, as long as you don't try to get 1200W of sound of them. And most people can realize this. But I'm very accustomed to working with people who, shall we say, are a few cents short of a dollar regarding common sense, so I make a habit of putting VERY CLEAR DISCLAIMERS IN ALL CAPS so that nobody can trace their blown amp back to something I said that was misinterpreted.
 
Oh well of course :p

Im no audio amplification expert, but I know enough to not ty and get triple what I can out of something.

If you are over/underpowering your speakers the best thing to do is just listen for distortion and back off right?
 
PLEASE PLEASE IGNORE THIS. not because it's wrong, but because it's dangerous.

You should never underpower your speakers, just like you should never overpower your speakers. The closer to max you push an amp, the more noise you're sending out, which can damage speakers. Your amp's capacity should be greater than your speaker RMS rating, but lower than your speaker's max rating as a general rule of thumb.
I keep saying this but there is no such thing as an amp being over or under powered for a speaker, it is all a matter of the application. If you can get sufficient output and headroom from a system with an amp rated at 1W then you are not 'underpowered' regardless of what the speaker is rated. And you can run a 100W continuous rated speaker on a 10,000W rated amp all day as long as the application allows it. The problem is not of the amp being over or under powered based on the speaker but rather of being over or under powered based on the application.

A 100W speaker on a 1,000W amp is not a problem unless you try to get more from the system than the speaker can handle. Conversely, a 100W amp on a 1,000W speaker is not a problem unless you try to get more from the system than the 100W amp can support. Run the system within the necessary parameters and either situation can work just fine. The problems typically come in when people push a system outside its safe operating parameters, something more likely to happen with less knowledgeable and experienced operators. This is where the 'rules of thumb' such as 1.5 times the speaker's continuous power rating come in, that is assuming an generic application where you want to get the most output possible from the speaker with a reasonable level of safety. It is in no way suggesting that you can't run with a lower, or higher, rated amp as long as it works for the application.

Also, there is no such thing as RMS Watts. The more proper rating is continuous or long term Watts, reflecting the time period of the test.

Here's the deal with amps, ignore power and start thinking in terms of voltage and current. After all, amps do not output power, they output voltage and current which in turn delivers power into a load, in the case of an audio amp that load is usually one or more speakers. Look at how amp specs identify power at a certain impedance, they are not measuring the power out of the amp but rather the power delivered into that load (which is also an idealized load and not really representative of the complex impedance of a speaker). It is the maximum voltage and current an amp can provide that determines the power it can deliver into a particular load. If the the load is too small, too low an impedance, an amp can have problems providing sufficient current.


As far as the XTR-400, I have no idea what to do. Because it was a packaged system with a crossover and amp, there is apparently no information on the sub itself such as impedance, power ratings, crossover recommendations, etc. About the only potentially relevant info I could find is that the internal amp for the sub was rated at 230W"RMS", apparently into whatever impedance the sub is (probably 8 Ohms but who knows). If you really want to use the XTR-400 that you have without the amp in it, then what you need is a crossover and another amplifier. Line left and right into crossover, left and right high/mid out of the crossover into your existing amp powering the existing speakers in stereo mode. Mono low out of the crossover into another amp in bridge mono mode to power the sub. And hopefully you get the amp and crossover settings right before you fry the sub. And even if you get it right, how beneficial it will be, if at all, is unknown.


Added: Here are some related references, http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm, http://www.crownaudio.com/amp_htm/amp_info/how_much_power.htm and http://www.qscaudio.com/support/library/papers/puzzle.pdf.
 
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I have a 800 watt amp running two 1200 watt cabs (Personell) but the amp is never at its max.
I was surprised that 400~ watts was enough to move the cones.
Why were you surprised? A little food for thought:

The difference in the output of the speakers between 400W and 1,200W is less than 5dB.

If 1,200W is the peak output and you have a fairly typical crest factor of 10-12dB for the signal, then the average output is 76W to 120W.

Say the minimum level in your source is 40dB down from the peak, that's 1,200W versus 0.12W. Make it a 50dB difference and it's 0.012W.

If your amp has a 100dB S/N ratio then with a 1,200W rating that means the noise floor would be a 0.00000012W output.


We typically deal with signals that vary greatly in level, not just peak levels but also average levels, and this is a critical factor when discussing amplifier and speaker power. Probably as many if not more speaker failures result from thermal issues related to excessive long term average levels than from overexcursion related to excessive instantaneous peaks. As always, one really has to consider what you are trying to do and the application rather than just some of the product ratings.
 
When I test my speakers I plug them into the headphone output of a Transistor Radio. This is a max power of 0.2 watt. works great and sounds good too. You would be amazed at how loud 0.2 watt is on an 18 inch 400 watt speaker because they are so much more efficient than a transistor radio speaker.

There is no such thing as underpowering a speaker. Manufacturers of speakers put Minimum power requirements on speakers to sell amplifiers. After all, when you fade the sound down to nothing, you are fading the power to zero and it sounds fine all the way down doesn't it ?
 
There is no such thing as underpowering a speaker. Manufacturers of speakers put Minimum power requirements on speakers to sell amplifiers.
A 500W speaker on a .2W amp is underpowered no matter how you look at it. That doesn't mean it's bad or dangerous, just that the amp is not capable of supplying enough power to drive the speaker to its capabilities.

As for the second statement, the minimum rating is what the manufacturers deem necessary to drive the speaker to its capabilities. Aside from the fact that I've never seen a minimum power requirement (I'm sure they exist), I really don't see how this affects amp sales. (unless you're talking about radioshack-type equipment, which is pretty unrelated anyway)
 
A 500W speaker on a .2W amp is underpowered no matter how you look at it. That doesn't mean it's bad or dangerous, just that the amp is not capable of supplying enough power to drive the speaker to its capabilities.
A 500W speaker on a 0.2W amp is not underpowered unless it cannot fulfill the needs. Your last statement about "drive the speaker to its capabilities" is the critical factor, you are assuming that is the goal when that is not always true. I have a theatre system out for bid right now that as a result of selecting equipment to meet other specific goals (coverage, intelligibility, reliability, etc.) will probably never be run anywhere near its full output. You are assuming a certain goal and that is the critical factor.

As for the second statement, the minimum rating is what the manufacturers deem necessary to drive the speaker to its capabilities.
Absolutely wrong. The continuous rating you see published for speakers is the average power applied for some period of time for which the speaker failed in some manner. It could be a minor failure from which it can recover or a major one that is terminal, you don't know. All you know is that the speaker failed in some manner when a specific signal of that average power was applied for some period of time. It is the maximum, not minimum, recommended long term power for the test signal used.

That gets into another aspect. The test signal most commonly used is a shaped noise spectrum that is intentionally clipped to have a 6dB crest factor (peak level to average level). How much that resembles an actual signal in use depends on the actual signal. It is also why the peak ratings for speakers are typically 6dB or four times the long term or continuous ratings, that peak rating is not measured it is simply the continuous rating with the 6dB crest factor of the test signal added in.

Another aspect, the continuous power ratings are for failure of some type but the performance of the speaker may change significantly before that failure occurs. There has been a push to revise the speaker testing procedures to base the power ratings on a 3dB change in response at any frequency, in other words any generally audible change in response. This is being resisted by many manufacturers as according to the people who do the speaker testing and have applied this approach on an experimental basis, the resulting power ratings would be much lower for many speakers. Thus a speaker tested to such a standard might fair poorly against speakers tested to the current standards when just the numbers are compared and not the test procedure. And how many people buying through Full Compass, Sweetwater, Musician's Friend, etc. are going to be comparing the test procedures used and not just the numbers?

Aside from the fact that I've never seen a minimum power requirement (I'm sure they exist), I really don't see how this affects amp sales. (unless you're talking about radioshack-type equipment, which is pretty unrelated anyway)
Minimum power requirements do not exist in terms of a speaker, they only exist in terms of an application. A speaker would work fine with whatever power is provided.

A major missing element in this discussion is sensitivity. Speakers have a sensitivity rating, which is how effectively they convert the electrical signal applied to an acoustic signal and normally defined as the output at some distance derived from some reference input level, the most common values being 1 Watt input at 1 meter from the speaker. So say you want a specific output, one speaker may have to be driven at its full rated power to provide that output but to get the same result a different speaker with a greater sensitivity can be driven with a lower level signal and provide the same output regardless of it being below its full power rating. Once again, the determining factor is the result and not the power rating.
 
At this point we've lapsed into some serious picking of nits, especially about exactly how 'underpowered' is defined. I couldn't find any good definition of it on the interwebs; I'm using it as a general term to describe when an amp is not capable of driving a speaker to its capability, whereas you're using it as a technical term for an impossible situation.

Considering the fact that I'm sure we both understand each other, I'll just leave this with your (far more in depth and knowledgeable) post above mine there.
 
At this point we've lapsed into some serious picking of nits, especially about exactly how 'underpowered' is defined. I couldn't find any good definition of it on the interwebs; I'm using it as a general term to describe when an amp is not capable of driving a speaker to its capability, whereas you're using it as a technical term for an impossible situation.
It is not picking nits, the idea of a speaker being 'underpowered' based on its power rating is actually one of the most common misconceptions in audio.

The continuous or long term power rating for a speaker is simply how much power a speaker was able to handle during testing based on a certain audio signal and certain conditions before some type of failure occurred. It has nothing to do with how much power a speaker needs or should have, that is determined solely by the application.

Where things usually seem to get confused is in the often unspoken assumption that one always wants to get the greatest output they can, or safely can, from a speaker. This is an easy perception to have when one usually dealings with systems that may not be up to the task at hand and you always seem to be trying to get more from the system that it can deliver. However, that is not applicable to every situation and there are times when you do not need the maximum possible output from the speaker as long as you can get the levels and headroom required for the application. Focusing on the power ratings and ignoring the sensitivity ratings and output can lead to erroneous conclusions.

Here's a simple example. Say you have one speaker rated at 250W continuous and 95dB/1W/1m sensitivity and another speaker rated at 1,000W continuous and 100dB/1W/1m sensitivity. And you have a 500W/channel amp. If one looks at just the power ratings they might say the first speaker is properly powered and the second speaker is very underpowered. Yet based on the rated sensitivities and power that is available, the second speaker is able to generate 127dB/1m, and to do so for long periods or with signals with minimum dynamics, while the first speaker is capable of only 122dB/1m. Is the second speaker actually 'underpowered' when it is 5dB louder than the other one? If the goal is to have 125dB/1m, which system is actually underpowered?

Or look just at the second speaker. If the goal is 125dB then meets that goal with a 316W per channel amp and with 500W per channel is not 'underpowered'. But what if the goal was 130dB/1m, not it needs 1,000W per channel and is underpowered at 500W per channel. Note that the what determined whether it was underpowered or not was the result, the output level, and not the speaker power rating.
 
You get most the the volume you need with the first 10 watts of power that you provide the speaker, in fact many times 1 watt is enough.

Then everytime that you double the power you will only get 3db more volume from the speakers.

I have a 2000 watt system that I use every week, yes it is very loud at 2000 watts max, about 110 DB or so, but think about it.
This system is only 24 DB less volume at 8 watts.
 
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