[JohnnyTwoTone]

For the longest time I was under the impression that it was a 'bad' thing to send more watts RMS from your amp than the component (let's say a mid-bass woofer for argument's sake) is rating to take. Ie. My mid-bass woofer is rated at 150watts RMS at 4ohms, I have an amp that outputs 150watts RMS at 4ohms per channel so I, as I understood it, everything was as it should be.

But, I read all the time of people sending more power than the component's rating on purpose claiming it to be a good thing.

So, my question is how does one go about knowing how much power is the optimal amount?

I ask this now because I plan on getting a new set of tweeter to run active but I have two amps - one runs at 85watts RMS per channel and the other runs at 150watts per channel. I certainly don't want to fry any tweeters so what is the ceiling as far as tweeter power ratings go? Can i use a set of tweeters rated at 50watts RMS with that 85watts RMS per channel amp? How about 40watt tweeter, etc?

 

[tspence73]

More powa, more SQ's. That's how I see's it. But people have been known to disagree with me before...

 

[killerb87]

headroom.

 

[JohnnyTwoTone]

More powa, more SQ's. That's how I see's it. But people have been known to disagree with me before...

Haha, well that doesn't really answer my question. Just HOW do people know when it's 'enough' and not 'too much'?

Basically, how low rated of a tweeter can I use on a 85watt RMS 4ohm amp before I risk damaging it?

 

[mikey7182]

A lot of it has to do with setting your gains. Honestly, you could run an amp rated at 1000x2 to a pair of mids, and as long as the gains are set appropriately, you're not hurting anything. Just because an amp is rated to output a certain amount doesn't mean it is always putting that power out, or that your speaker is seeing that much power. The reason you see people here running amps that may appear to do 2-3 times the RMS of their drivers is for several reasons. First off, RMS tests are done on a bench, usually with pink noise (IIRC) for a certain period of time. It is a good general indication of what the speaker will handle, but by no means the final authority on how much power to send your speakers. Second, while playing music, amplifiers do not output constant wattage. It fluctuates with the demands/dynamics of the music playing. So you may have 10-40 watts playing, with peaks upwards of 150, but those peake will not be constant. A lot of people, myself included, run larger amps for headroom. If you're only wanting say 100w/driver on tap, and you can pick up an amp that is rated at 300w/channel, you're able to keep your gains low, which helps your amp run cooler, more efficient, and ultimately, provide a cleaner signal to your drivers.

Edit: Just realized I went off on a tangent rather than answering your question. As far as knowing what is "optimal" to run to your speakers, there really isn't a range. There are a variety of factors that play into how much power a speaker will handle. For a mid, how low is it crossed, and at how steep a slope? HP your mids at 125hz at a steep slope, and send them 100w. Now HP the same mid at 63hz at a more shallow slope and see how they like the same power. If it is a robust mid, it may do fine. If it isn't designed to play that low at high output, you will likely damage the driver. I go back to my original statement that it has to do with setting the gains conservatively and intelligently, and that more comes with experience than following a guide, because of the factors involved. Hopefully that helps.

 

[shadowfactory]

Also what he said ^

More powa, more SQ's. That's how I see's it. But people have been known to disagree with me before...

Jokes that aren't funny still count as threadcrapping especially when you offer up no real contribution to the thread.

To add to the thread, power is not absolute, there is a gain knob on the amp and levels in the processor that can be adjusted to make more power workable, you just have to be careful that you don't accidentally introduce more distortion and go beyond thermal limits of drivers by overpowering them.

 

[tspence73]

A lot of it has to do with setting your gains. Honestly, you could run an amp rated at 1000x2 to a pair of mids, and as long as the gains are set appropriately, you're not hurting anything. Just because an amp is rated to output a certain amount doesn't mean it is always putting that power out, or that your speaker is seeing that much power. The reason you see people here running amps that may appear to do 2-3 times the RMS of their drivers is for several reasons. First off, RMS tests are done on a bench, usually with pink noise (IIRC) for a certain period of time. It is a good general indication of what the speaker will handle, but by no means the final authority on how much power to send your speakers. Second, while playing music, amplifiers do not output constant wattage. It fluctuates with the demands/dynamics of the music playing. So you may have 10-40 watts playing, with peaks upwards of 150, but those peake will not be constant. A lot of people, myself included, run larger amps for headroom. If you're only wanting say 100w/driver on tap, and you can pick up an amp that is rated at 300w/channel, you're able to keep your gains low, which helps your amp run cooler, more efficient, and ultimately, provide a cleaner signal to your drivers.

Edit: Just realized I went off on a tangent rather than answering your question. As far as knowing what is "optimal" to run to your speakers, there really isn't a range. There are a variety of factors that play into how much power a speaker will handle. For a mid, how low is it crossed, and at how steep a slope? HP your mids at 125hz at a steep slope, and send them 100w. Now HP the same mid at 63hz at a more shallow slope and see how they like the same power. If it is a robust mid, it may do fine. If it isn't designed to play that low at high output, you will likely damage the driver. I go back to my original statement that it has to do with setting the gains conservatively and intelligently, and that more comes with experience than following a guide, because of the factors involved. Hopefully that helps.

x2. I like this explanation.

 

[JohnnyTwoTone]

Okay, how about this (current) scenario: I have a tweeter rated at 10watts RMS. If I hook it up directly to the 85watt RMS amp, set the gains correctly and dick with my Eclipse deck (CD8454) I can assure that I won't blow said tweeter? Or is a tweeter of that low watt rating something that needs to be left in a passive system?

Or how about the idea of hooking the tweeter directly to the deck's power output and have the woofers on the amp then use the deck's cross-over options to tweak accordingly?

 

[capnxtreme]

If you have the HP high enough, and the gain low enough, it should be fine.

 

[JohnnyTwoTone]

...how come my signature isn't showing up?

EDIT: Oh, there we go.

 

[SQplease]

my rule of thumb is that I like to double what ever the speaker rms is and 1 1/2 times that at the least. the reason being that one: you can drive it to a reasonable volume without clipping( headroom) two brings out better performance in your drivers and saves the life of your amp. ofcourse you are not going to turn it up full volume nor do most people go 3/4 of they way. bottom line the amps can preform inside its spec's without being over work and loosing SQ. this is only my beliefs and testing.

 

[mikey7182]

Okay, how about this (current) scenario: I have a tweeter rated at 10watts RMS. If I hook it up directly to the 85watt RMS amp, set the gains correctly and dick with my Eclipse deck (CD8454) I can assure that I won't blow said tweeter? Or is a tweeter of that low watt rating something that needs to be left in a passive system?

Or how about the idea of hooking the tweeter directly to the deck's power output and have the woofers on the amp then use the deck's cross-over options to tweak accordingly?

I'd use the 85w/channel amp on the tweeters and the 150w/channel amp on the mids, like you planned. If your plan is to run them active, you'll probably want the gains on your tweeter amp a notch above minimum. Without a scope, it's hard to say exactly, but I think the preout voltage on that Eclipse is pretty strong (8V?) so your amps will be getting a strong signal. You can still use the active xover on the deck to send the appropriate signals to both mid and tweeter.

Here's what I'd suggest: after setting your xover points, get a cleanly-recorded album, i.e. Dire Straits, Dave Matthews, Days of the New, etc, and use it to set your gains. Listen for any clipping, mild popping, etc as you turn it up one notch at a time. If you start to hear any clipping, back the gains down a bit. This is assuming you're going to set the gains by ear (the only way I've ever done it). In 11 years, I've never blown a driver, amp, deck, or other piece of equipment. Just don't get zealous with the gains and you'll be fine.

 

[TREETOP]

Power ratings can be altered by tweaking the frequencies that a speaker receives, also.
For example, let's say a midrange is rated at 80 watts RMS. It was likely meant to handle that 80 watts from its natural bottom rolloff to its natural top rolloff- let's say 60hz-6khz just as an example. BUT if it were crossed over bandpass to say 400hz-3.5khz, it can usually handle plenty more power. Reason being, it's now in the frequency range that it handles best, without either too much excursion or top-end breakup.

Make sense?

 

[JohnnyTwoTone]

^^Thanks! That's what I'll be doing for sure. I'll use the Titan (85watts per channel) amp for the tweeters, the first two channels of the PDX for the woofers, and bridge the back two channel on the PDX for my sub. Personally I hate subs but when I figured out that I'd have to build some sorta' contraption to put proper mid-bass woofers into, to get proper bass without a sub, I figured I'd just buy a thin line sub in it's corresponding box and call it a day.

Now I just need to find a high quality set of main tweeters that aren't ear bleedingly harsh like the CDT's I have are.

 

[Lanson]

You'll probably fry your ears before you fry a tweeter if you are making clean power for them, and if they are crossed over appropriately.

"Sending power" to a speaker doesn't really mean much unless you enjoy listening to test tones or something, because music is dynamic and the power you are using changes constantly.

The ability to push out tons of power to a speaker is essentially headroom. Don't forget that wattage squares w/ volume, so it doesn't take long before all your extra power is used up.

 

[npdang]

You're making 2 incorrect assumptions.

#1 - That the "power rating" of the speaker is meaningful. Ask yourself, under what conditions and for what length of time is that rating accurate? Can I even begin to guess the answer to that question?

#2 - That your amplifier is continuously operating at maximum output. Music is dynamic in nature; there are parts of a song that can be quite loud, and others that are not so loud. The output of your amplifier will vary depending on how "loud" you are listening as well as how "loud" a portion of the song being played back is.

How does one go about determining the optimal power requirements? Generally experience.... however some factors to consider are these:

1. how efficient are your speakers?
2. how far away are you sitting from the speakers?
3. how loud do you typically listen?
4. how loud is the ambient environment?
5. are there any obstructions (trunk wall, door panel, seat) blocking the sound?

Unless size or budget is a constraint, I would always err on the side of more power. It's always easy to "setup" an amplifier such that it never uses anywhere near it's maximum output capability... however, it is not advisable to try to squeeze more output from an amp than what it is rated for.