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Discussion Starter · #1 · (Edited)
Hi all, I have JBL Northridge speakers with an S center. A few months ago I bought a Onkyo TX NR5008
receiver. I recently noticed distortion from my center speaker. I'm fairly certain the center speaker is blown, The crossover board looks fine. I checked the watt output on my receiver and found that it has three watt outputs listed and wondered why....

Output Power / Channel
145 Watt, 175 Watt, 185 Watt

My concern is that my speakers cant handle the power ..
I never play them really loud and use no kind of compression via the receivers ability to do so..I use no EQ.
Is this receiver too much for my speakers?

any advice would be great..

George
 

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From the manual:

145 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven from 20 Hz to 20 kHz, with a maximum total harmonic distortion of 0.05% (FTC)
175 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.7% (FTC)
185 watts minimum continuous power per channel, 6 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.1% (FTC)

Are the differences obvious? The 145W number is the most relevant.

I wouldn't worry about the receiver being too much, as long as you don't drive the speakers to painful volume levels for long periods.
 

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Hi,

No, you didn't cook them with too much power. That power rating is continuous when actually attenuated to max output with the volume control. It's not the full wattage out of the gate with no way to attenuate that level. Instead, your receiver is likely down at -25db to -10db or something (guessing) and it's barely using 15~35 watts in reality to do your listening level. Maybe less, maybe a bit more. But if you're not sitting at your volume maxed out, you're not touching the full rating of the continuous output ability of those amps.

If your center speaker's woofers, voicecoil or crossover has a fault somewhere, that has nothing to do with a little load from a receiver. It just failed. It maybe failed earlier than it should have. But that's all it is. Don't read it into it like you overpowered some speakers with a receiver.

Very best,
 

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Discussion Starter · #4 ·
From the manual:

145 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven from 20 Hz to 20 kHz, with a maximum total harmonic distortion of 0.05% (FTC)
175 watts minimum continuous power per channel, 8 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.7% (FTC)
185 watts minimum continuous power per channel, 6 ohm loads, 2 channels driven at 1 kHz, with a maximum total harmonic distortion of 0.1% (FTC)

Are the differences obvious? The 145W number is the most relevant.

I wouldn't worry about the receiver being too much, as long as you don't drive the speakers to painful volume levels for long periods.
Silly question but how does my center know what watt rating to use? Is there a setting?


Now the next question if I may. I have serveral JBl speakers from the same series. Would I be able to use a slightly larger speaker in my center from a surround speaker or would that put a strain on the crossover board?
 

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Now the next question if I may. I have serveral JBl speakers from the same series. Would I be able to use a slightly larger speaker in my center from a surround speaker or would that put a strain on the crossover board?
You can use any speaker as a center. Ideally, a full range big one since in movies, it's most of the information so it really needs to be the best most competent speaker (not the smallest, unfortunately, which seems to be what everyone is selling as `centers'!).

What do you mean put a strain on the crossover board? The passive crossover separates the frequencies between the woofers/tweeters. Has nothing to do with use as a center or main or anything.

Very best,
 

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Hi all, I have JBL Northridge speakers with an S center. A few months ago I bought a Onkyo TX NR5008
receiver. I recently noticed distortion from my center speaker. I'm fairly certain the center speaker is blown, The crossover board looks fine. I checked the watt output on my receiver and found that it has three watt outputs listed and wondered why....

Output Power / Channel
145 Watt, 175 Watt, 185 Watt

My concern is that my speakers cant handle the power ..
I never play them really loud and use no kind of compression via the receivers ability to do so..I use no EQ.
Is this receiver too much for my speakers?

any advice would be great..

George
What’s the speaker power ratings/specs? Most times speakers are killed from the power amp or receiver clipping.
 

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Discussion Starter · #7 ·
You can use any speaker as a center. Ideally, a full range big one since in movies, it's most of the information so it really needs to be the best most competent speaker (not the smallest, unfortunately, which seems to be what everyone is selling as `centers'!).

What do you mean put a strain on the crossover board? The passive crossover separates the frequencies between the woofers/tweeters. Has nothing to do with use as a center or main or anything.

Very best,
My bad, I should have clarified, Im still going to use the same JBL s center but just switch out the blown speaker with another speaker from the same series, (The surrounds) take out the bad speaker and replace it...its the same series, just a tad bigger speaker but it fits..
 

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Over the years I have found that more people blow out speakers with underpowered amps and receivers.
The reason is that they are driving the amp into distortion. I have rarely seen a higher powered amp blow a speaker.
Not saying that this can't happen if one blasts it into distortion but it is unlikely.

See below:
"Under powered amps will wreck your speakers because people over drive them, when you over drive an amp it obviously clips. Clipping is the most common reason for blown tweeters. Under powered amps will wreck your speakers because people over drive them, when you over drive an amp it obviously clips"

Good explanation:
 

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My understanding of the problem with clipping is that is generates harmonics from low frequencies. (The amps usually need to produces lot more power at low frequencies than for the highs, to make normal sound levels.) The harmonics fry the tweeters.

Audiophiles sometimes like to have amps that can produce peak powers that are much higher than the speakers can tolerate for long periods. The commonly used term is "headroom".

For normal listening, efficent speakers may only use a few Watts.
 

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OK, quite simple

Speakers are damaged either thermally or mechanically. They are damaged thermally by applying too much power for too long which then overheats the voice coil. The voice coil can get so hot it burns off the varnish on the coil which can char, jam the coil in the gap or burn the coil in half. You can smell them getting hot as the varnish starts to off gas, you then see smoke if you are lucky before it utterly fails. Congrats, you just voided your warranty!

The second way is mechanically, you apply too much power at a frequency that demands the cone/dome/ribbon to move farther than it is able to do without damage. This can do several things, in a cone it can create so much pressure/force that the cone deforms and buckles (easy to spot that) It can eventually tear the spider or the coil that holds the back of the cone in place and or rip the surround around the cone. Worst case scenario, it can drive the voice coil into the magnet which damages the voice coil, deforms it and jams it in place. Congrats, you just voided your warranty!

This tends to happen when wine, women and song become involved and your golden ears are now clay thanks to the spirits that move you. The next morning, you can spot creased or buckled cones, ripped surrounds by looking at them. Take a good sniff and you might smell the burned varnish of thermal failure. Lightly press on the cone, if it has a crunching sound (burned voice coil char) or is frozen in place--you trashed the driver. You can also burn up power resistors in the passive crossover, blow out a capacitor (look for leaks/burn marks) or, if equipped, the crossover might have fuses or lightbulbs that are blown.

A multi-meter helps, when you remove the driver with the wires disconnected--ohm it out. If it has infinite resistance, you burn the voice coil in half. Rarely will it be shorted as that demands the varnish to burn off exposing the copper coil then jamming it into the conductive magnet. It can happen but not very often. Either way, it's toast.

If both drivers look OK, they smell OK...if you can look at the voice coil color--looks like copper and not charcoal (subs with vented spiders are easy to see) then you can check the woofer or mid by wiring it direct to the amp IF it measures approx the stock resistance. Play some music through it or talk radio (better if a mid) and if it's good, then look at the crossover. If your other speaker works, you can swap crossovers to see if it works. If it does, then you have a damaged crossover, crossover fuse or a blown self-resetting breaker.

Both of those scenarios be they thermal failure or mechanical failure as long as the drivers were not defective is caused by too much power applied. Thermally is obvious, you turned your voice coil into an expensive fuse and burned it. This is caused by a higher thermal or electrical AVERAGE load than it can handle. Mechanically is also related to too much power, if you have say... a 5" two-way speaker that is tuned to 45Hz through the port and rated at 100 watts for example. Now play something that has a 22Hz tone in it at 100 watts, that demands the cone to move 4 times farther than it would at 45Hz. Uhhhh.... if it is at it's linear limits at 45Hz then 22 Hz will attempt to drive it 4 times farther and goodbye driver! You applied too much power outside the speakers pass band of operation...play Bass I Love You with dropped bass tones hitting 8Hz and get an idea.

Too much power... clipping in and of itself does not damage speaker drivers. Clipping will cut the top off waveforms but even true square waves do not destroy speaker drivers. My test disc for testing speakers has square waves of varous tones--no, the drivers don't blow up. What clipping DOES do is compress the signal--that creates very, very high AVERAGE power applied to the voice coil. For example, say the speaker can handle 100 watts from a signal that has 10dB of dynamic range. Soft parts at 10 watts, loud parts at 100 watts in it's passband. Now drive it into "soft clipping" and the soft parts are at 20 watts while the hard parts are at 100 watts. Drive it into "hard clipping" or 6dB of clipping and the soft parts are 40 watts and the loud parts are 100 watts clipped.

The average power keeps jumping strongly even though the peaks are chopped off. Eventually, you burn up the smallest voice coil first (tweeter) as the average power is so high it can't dissipate the heat. Tweeters are at a strong dissadvantage here because they barely move, more like shimmer so don't have air pumping action to cool the coil like a woofer or subwoofer does. They have very small diameter voice coils, very short because they don't move far and are generally encased in plastic for consumer dome tweeters. Compression drivers for pro sound, horn loaded systems can handle a lot more power because they are metal, large magnets to absorb heat, larger voice coils (generally 1.5 to 2 inches or larger) and at least 10 times or more output due to very high efficiency.

Does a coil of wire care what the waveform looks like? Not really, as long as it can get rid of the heat it won't burn up. This holds true as long as it is alternating current, throw a direct DC signal from a battery on it and it will throw out the diaphram and lock it in the extended and no movement state which will just burn up the coil. This is why you should never connect a 9V battery to your speaker wires and let it sit there...a quick crack across the battery will cause the driver to jump is all you need to know.

How NOT to blow up speakers--never exceed the power the voice coils can safely dissipate. Don't drive the speaker out of it's rated passband, either use high pass filters or subwoofers to protect the woofers from getting hammered. Speakers don't think, they have no soul, they are not magic as they are brushless electric motors that are rated a specific voltage, impedance and thermal handling.

The "clipping" thing... it is not the clipping, it is the power compression. If you have a 150 watt bookshelf speaker, it can be damaged by clipping a 100 watt amp fairly hard for a long enough time to either burn up the voice coils or mechanicaly damage the drivers if used outside of it's rating. The clipping raises the average power due to compression which the 150 watt rating is not rated for (look up the standard of how your manufacturer rates such things) If you purchase a 400 watt amp so it "won't clip"....wanna bet? Crank it, it will clip--kick an interconnect cable out of the back and you'll spike the imputs and clip the amp. Crank it up to 400 watts non-clipping for along enough, with a highly compressed waveform (dance music) and you will damage the driver. Either burn it up from too much power applied or mechanically destroy it from too much movement.

There is not such thing as "underpowering"... if low power applied damaged a speaker all the clock radios of the world, all the ceiling speakers in the malls across the world and car stereos would be on fire. Geez, why would we use volume controls?

More speakers are damaged by underpowering than overpowering. No speakers are damaged by underpower and ALL speakers are damaged by overpowering! Quit parroting garbage....quit reciting what the salesmen told you...understand what you are saying!

If you tend to crank up your music, get an amplifier that has power meters AND clip lights! I own a few of them, they light up the room as the clip light blasts out the lumens and hard to ignore. Most decently made outboard amplifiers have clip lights, they are good for proper gain matching and testing with multi-channel systems. If you don't like the look of power meters or clip lights, then you lose that ability. Avoid amplifiers that don't provide that as it implies you have to use your golden ears to detect it. Since I run multiple amps, I need clip and power lights just to get it setup and it's nice to know if there is an issue.

Don't clip your amp, the power compression heats up voice coils. If you demand more SPL than your speakers can provide on AVR power, you have the option to increase power with outboard amplification. If your speaker is rated 150 to 200 watts, be aware even with double the power you might gain 3dB but power compression from voice coil heating will take at least 1dB of that. Realistically, you need more efficient speakers if you want higher SPL levels--learn that before you purchase speakers to minimize wasting money/time/effort on constant swapping until you are lucky enough to get the right ones by accident.

Clipping amps means you did it wrong. Not enough efficiency from the speaker is the biggest cause. Not hard to get speakers that require 10 times less power to create the same SPL but very hard to find speakers that match the furniture that can handle a true 1,000 watts RMS for an 8 hour house party.

So there ya go, you burn copper in half by applying too much power for too long until it gets so hot it burns the varnish off, starts to melt to the other coils and eventually fails from heat. Voice coils burn up from too much power just like fuses burn up from too much power. Mechanical failure is caused by too much power in the passband or too much power outside the passband. It is up to you to know that and plan accordingly.

Just for those that wonder how it actually works VS being a parrot quoting audio foo that is not based in reality. Another audio quote from Captain Obvious... don't overdrive any part of the audio system to help keep distortion at bay. This means don't clip the source, don't clip the pre-amp, don't overload the inputs to the amp, don't overdrive the outputs of the amp and don't overdrive the speakers. Yep, that is on you so if you care not to break things, read up on how that is achieved. Hint, it is not more power...
 

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@18Hurts, great explanation. Your clipping explanation I understand. Most of us when we say clipping kills speakers it’s because clipping causes distortion. That distortion, understanding your post, causes mechanical problems which can intern also created too much heat at a determined frequency outside of the speaker specs. Eventually causing the speaker or crossover to fail. Guess we all talk too much in generalities for your taste.

How much of your knowledge came from experiencing failures? I know I have had a few. Lol 😆. That over powering speaker post you wrote perfectly described me killing a center channel speaker. Smell and all. 😩😩😩
 
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