Cheap preamp/amp on high end speakers?

[shadyJ]

So the main problem is the energy going to the Tweeter.

If the amp clips, additional power may be shifted toward the Tweeter.

But even if the amp doesn't clip, the if the tweeter gets more than 20 or 30 Watts, it would still overheat the voice coil.

Case#1.
Speaker is rated for "500W". Amplifier is 200 Watts.

Silk Dome Tweeter Power Handling (ScanSpeak 9500):
https://www.scan-speak.dk/datasheet/pdf/d2905-950000.pdf

100h RMS noise test = 150 W
Long-term Max power = 460 W

If the amp clips, up to 400W goes to the total speaker (all drivers). But perhaps a lot of that 400W goes to the Tweeter.

In this case, the tweeter might possibly handle the clipped energy since the peak power handling is 460W.

Case#2.
Speaker is rated for "500W". Amplifier is 200 Watts.

Diamond Dome Tweeter Power Handling (Seas Excel T29D001):
https://www.madisoundspeakerstore.com/diamond-dome-tweeters/seas-excel-t29d001-diamond-dome-tweeter-matched-pair/

Short-term = 150W
Long-term = 55W

If the 200W amp clips, a lot of the possible 400W could go to the Tweeter. Short-term or long-term, this tweeter is fried.

But what if the amp is 1,000W and doesn't clip, but volume is almost at max? Couldn't 200W of the 1,000W amp go to the tweeter anyway and fry the tweeter even if the amp NEVER clips?

Or for long-term, couldn't more than 75W of power go to the tweeter even if the amp never clips?

Nature of the signal matters here. These drivers can handle a lot more power in short bursts than continuously. The drivers can be destroyed not just by overheating, but also by over-excursion. Obviously, over-excursion happens at lower frequencies where overheating is more likely at higher frequencies, so the frequency of the signal matters. So all of these specs are a bit ambiguous. They are ball-park, rounded-off numbers, not precise points of failure. Furthermore, its not the distortion itself that harms the drivers, but just receiving too much current. The driver doesn't know that the signal is distorted. A lot of music is filled with intentional distortion anyway that isn't much different than what the voltage waveform looks like with amp clipping anyway. What is more, measures can be taken within the crossover to protect the tweeter from too much current, such as the implementation of polyfuses. The bottom line is that if you are playing your content loud, and something sounds off, you should back down on the volume right away right away.

 

[AcuDefTechGuy]

Nature of the signal matters here. These drivers can handle a lot more power in short bursts than continuously. The drivers can be destroyed not just by overheating, but also by over-excursion. Obviously, over-excursion happens at lower frequencies where overheating is more likely at higher frequencies, so the frequency of the signal matters. So all of these specs are a bit ambiguous. They are ball-park, rounded-off numbers, not precise points of failure. Furthermore, its not the distortion itself that harms the drivers, but just receiving too much current. The driver doesn't know that the signal is distorted. A lot of music is filled with intentional distortion anyway that isn't much different than what the voltage waveform looks like with amp clipping anyway. What is more, measures can be taken within the crossover to protect the tweeter from too much current, such as the implementation of polyfuses. The bottom line is that if you are playing your content loud, and something sounds off, you should back down on the volume right away right away.

Very interesting about the intentional distortion in music that looks like the waveform amp clipping.

Woofer = Mechanical (excursion) Damage
Tweeter/Midrange = Thermal (heat) Damage

Any speakers out there using poly-fuses to protect the tweeters? I heard the RBH speakers have tweeter protection in their crossovers.

I think this topic is huge and many people wonder about it.

What's more dangerous, more power or less power? Of course, it depends, but the specifics are good to know.

I think Audioholics could use a detail article on this topic.

 

[shadyJ]

Very interesting about the intentional distortion in music that looks like the waveform amp clipping.

Woofer = Mechanical (excursion) Damage
Tweeter/Midrange = Thermal (heat) Damage

Any speakers out there using poly-fuses to protect the tweeters?

I think this topic is huge and many people wonder about it.

What's more dangerous, more power or less power? Of course, it depends, but the specifics are good to know.

I think Audioholics could use a detail article on this topic.

Well, both the woofer and tweeter can be overdriven with excursion or overheated with thermal overload. It all depends on what signal they are being fed.

RBH uses polyfuses in their speakers, to name one manufacturer.

As far as more or less power being more dangerous, it's not so much sheer quantity as where and how that power is being distributed.

Regarding an Audioholics article, there already is a great series: Loudspeakers and Power Handling: Parts I, II, and III.

 

[PENG]

Very interesting about the intentional distortion in music that looks like the waveform amp clipping.

Woofer = Mechanical (excursion) Damage
Tweeter/Midrange = Thermal (heat) Damage

Any speakers out there using poly-fuses to protect the tweeters?

I think this topic is huge and many people wonder about it.

What's more dangerous, more power or less power? Of course, it depends, but the specifics are good to know.

I think Audioholics could use a detail article on this topic.

You made a lot of good points in your several posts. Unfortunately as you said it yourself, it really depends. For example, you have linked the data sheets of two tweeters and obviously one can handle a lot more heat than the other so it doesn't seem right to generalize. I can tell you one thing for sure that a 300 W/500 W 8/4 ohm rated power amplifier will have a much greater chance of damaging the tweeter of a speaker than a 125 W rated AVR would, in the wrong hands.

I understand M Code's point, but as you alluded to, we really don't know the full context of his conversations with those "chief engineers". When an engineer answers a technical question, he/she may not always fully understood what is being asked, and some of the so called engineers may not even be engineers qualified to answer the specific questions correctly. For example, he/she may be a loudspeaker design specialist in crossovers and enclosures, but may not have a strong background in all things related to power, energy, harmonics, their inter relationship, heating effects etc.

Take a look of the Salon2's impedance curve:
https://www.soundstage.com/measurements/speakers/revel_ultima_salon2/

The impedance of a driver is quite complex, but even if you look at the voice coil of the one you linked in isolation all by itself (without considering the crossover and the enclosure effects),it has resistance and inductance. The inductive reactance (the inductive part of the total impedance) will naturally increase with frequency. So I am quite sure the impedance increasing trend starting at 10K will keep on rising as frequency increase, and that means the higher frequencies voltage components due to clipping will see higher impedance of the tweeter as the frequency of the harmonics increase. That would have the tendency to limit the increase in the harmonic currents due to the clipped voltage waveform. There are many factors and variables to consider, making it hard to generalize in one way or another.

 

[M Code]

Are they saying just the distortion itself, regardless of the Power or Energy going to the drivers, is causing all the damage?

I assume they mean "a lot of distortion" in the form of "clipping" that causes more ENERGY (and high-frequency energy shift) to go to the drivers (especially tweeters).

But it makes sense to me that the excess ENERGY is what causes the damage.

If distortion occurs but the resulting energy is less than the limits of the drivers, how would this damage the drivers?

Distortion/power equals energy.. But note it is not just tweeters, even though a woofer has a bigger motor structure(magnet, voice coil, gap) extreme distortion increases the voice coil temperature often resulting in it coming apart(debonding) due to higher temperatures. Also a woofer cone tends to twist, and vibrate under high distortion conditions, sometimes exceeding its excursion specs and coming out of the gap.

Wouldn't AVRs have built-in speaker protection circuits that would cause the AVR to go into Protection Mode if clipping occurs?

Maybe, really depends if the distortion is continuous or simply a instantaneous dynamic peak. If the condition is instantaneous the protection circuit may be too slow to protect the loudspeaker. Either condition is very hard on a loudspeaker be it a subwoofer, mid-range or tweeter.

The Tone Controls point is interesting. I do know some people who love to use Tone Controls and Manual EQ to boost certain frequencies. If they were to boost the Treble frequencies, that could definitely push even more Energy toward the tweeter.

Any type of EQ can cause increased distortion, this is a significant problem especially when the tone control circuit is analog. Later digital tone circuits done within the audio DSP tend to have less distortion. Also remember Room EQ software can introduce boost as well depending upon setup conditions.

Bottom line..
My comments go far beyond conjecture or speculation..
In my career I have been VP of Marketing/Product Development for certain well-known audio brands who did significant sales $ not only in electronics but loudspeakers too. In this capacity I had direct access to field failures and warranty claims. If the loudspeaker was the weak link, it was my responsibility to test and validate the failure, and then institute design/component updates as to minimize future failures..

Just my $0.02...

 

[Cjamrr]

I’m going to figure this loudspeakers and power handling out pretty soon, I am happy to hear from everyone with your knowledge and experience.

From my stereo dealer, I can get a huge discount on the floor model Amps:
(1) Anthem MCA325 - $1800
(2) Anthem STR power amp - $4800/obo
(3) Anthem MCA225 (dealer would have to order, negotiable price not yet.)

Can I get a vote on which of the 3 from you.

I have:
Onkyo TX RZ 1100
Focal Kanta No. 2 (fronts)
Focal Chorus CC700 (center)
JL Audio E112 (sub)
JBL S310II (surround)

 

[PENG]

I would also add that the rated voltage of a 200 W amp is going to be 1.414X that of the 100 W amp, all else being equal. So even based on the scenario when a tweeter is damaged by a badly clipped signal, a 100 W amp has lower odds because one would hear the warning sign, i.e. audible distortions from clipping much sooner and at a lower voltage, i.e. lower current. Again, I am not drawing conclusion, just saying let's not generalize, as it truly depends, on many things.

 

[PENG]

I’m going to figure this loudspeakers and power handling out pretty soon, I am happy to hear from everyone with your knowledge and experience.

From my stereo dealer, I can get a huge discount on the floor model Amps:
(1) Anthem MCA325 - $1800
(2) Anthem STR power amp - $4800/obo
(3) Anthem MCA225 (dealer would have to order, negotiable price not yet.)

Can I get a vote on which of the 3 from you.

I have:
Onkyo TX RZ 1100
Focal Kanta No. 2 (fronts)
Focal Chorus CC700 (center)
JL Audio E112 (sub)
JBL S310II (surround)

(1) and (2) are reasonable prices but I think you can negotiate them a little more as they are floor models, $1500-$1600 would be more reasonable imo, for the MCA 325.

You really don't need the STR. On money no object, go for it, but in recent years I am getting increasing reluctant to spend more than I have to, considering nowadays they tend to jam much complexity and the associated electronics, including ICs (processors, multiplexers, tone controls, volume control, protection etc.) in one box. As soon as anything goes wrong, I would feel the pain of having to pack and send an expensive and typically heavy unit out for repair. I actually enjoy my HT set up more now that I replaced my $3000 AVP with a $1100 AVR.

So the MCA 325 gets my vote, but I would offer them $1500 to start and may accept $1600, otherwise walk and wait.. Or offer $150 more for one in a sealed box.

 

[AcuDefTechGuy]

I can tell you one thing for sure that a 300 W/500 W 8/4 ohm rated power amplifier will have a much greater chance of damaging the tweeter of a speaker than a 125 W rated AVR would, in the wrong hands.

Yes. Thank you. I got something right. That has been my understanding from trying to comprehend this topic.

The impedance of a drive is quite complex, but even if you look at the voice coil of the one you linked in isolation all by itself (without considering the crossover and the enclosure effects),it has resistance and inductance. The inductive reactance (the inductive part of the total impedance) will naturally increase with frequency. So I am quite sure the impedance increasing trend starting at 10K will keep on rising as frequency increase, and that means the higher frequencies voltage components due to clipping will see higher impedance of the tweeter as the frequency of the harmonics increase. That would have the tendency to limit the increase in the harmonic currents due to the clipped voltage waveform. There are many factors and variables to consider, making it hard to generalize in one way or another.

If it limits the increase in Current (Heat Energy), does that mean less Heat Energy could go to the tweeter?

 

[PENG]

Yes. Thank you. I got something right. That has been my understanding from trying to comprehend this topic.



If it limits the increase in Current (Heat Energy), does that mean less Heat Energy could go to the tweeter?

Absolutely, the relevant formula is:
Power = Current)^2 x Resistance (P = I^2 x R), therefore the heat developed in a resistor:

Energy = Power X Time (duration) = I^2 x R x T

The inductance of the voice coil won't contribute to heat, but it helps limiting the current especially at the higher frequencies, thereby also helps (only helps) limiting I^2 x R x T (I being the current, note the square relationship).

Another note, more heat energy means higher temperature and that means the resistance (R) of the voice coil will also increase, further reducing the current increase due to the increase in harmonic contents.

Again, I am not saying that a flat topped wave form created high order harmonics won't threaten a tweeter, because it certainly could, and may.. Just that one should not overrate this point to a make blanket/generalized statement about less power being more dangerous than too much power. All I can say is, and you said yourself, it depends, that's all.

 

[Cjamrr]

(1) and (2) are reasonable prices but I think you can negotiate them a little more as they are floor models, $1500-$1600 would be more reasonable imo, for the MCA 325.

You really don't need the STR. On money no object, go for it, but in recent years I am getting increasing reluctant to spend more than I have to, considering nowadays they tend to jam much complexity and the associated electronics, including ICs (processors, multiplexers, tone controls, volume control, protection etc.) in one box. As soon as anything goes wrong, I would feel the pain of having to pack and send an expensive and typically heavy unit out for repair. I actually enjoy my HT set up more now that I replaced my $3000 AVP with a $1100 AVR.

So the MCA 325 gets my vote, but I would offer them $1500 to start and may accept $1600, otherwise walk and wait.. Or offer $150 more for one in a sealed box.

Thank you PENG. I am going to bring both home to demo for a week. I like your choice as well for the MCA325, that would give me extra money to put towards something else in the system, possibly matching kanta center speaker or a better record player.

 

[PENG]

Thank you PENG. I am going to bring both home to demo for a week. I like your choice as well for the MCA325, that would give me extra money to put towards something else in the system, possibly matching kanta center speaker or a better record player.

The STR has better specs, but I am 99.9999% sure that 99.99999% of the population cannot tell the two apart in a properly done AB listening test if they are not allowed to use their eyes to listen. I have the MCA20 driving the front two channels for almost 8 years now and it is still in top shape. It has been virtually trouble free, except I don't use the signal sensing any more since it started to get noisy about 6 months ago. I don't think the MCAs will be as long lasting as Bryston's or Anthem's P series, but in terms of value for money, I can't complain.

 

[Cjamrr]

You have a good point. MCA325 sounds good enough for me. Just wanna make sure that it’s a good match.

 

[PENG]

You have a good point. MCA325 sounds good enough for me. Just wanna make sure that it’s a good match.

Of course, your Kanto No.2 has specs very similar to my 1028 Be. Guess what's driving them in the photo attached..



It's the little 5 W amp, and I checked with my RS spl meter, at 70-75 dB it sounded about as good as the big one it's sitting on.

The MCA 325 has 3 channels, that's a huge advantage over the STR if used in your HT set up. For 2 channel use only, if you really want to over kill it with a 2 chanel amp, you may want to consider the Bryston 4B SST3 as a viable alternative to the STR too.

 

[Out-Of-Phase]

Of course, your Kanto No.2 has specs very similar to my 1028 Be. Guess what's driving them in the photo attached..

View attachment 26500

It's the little 5 W amp, and I checked with my RS spl meter, at 70-75 dB it sounded about as good as the big one it's sitting on.

The MCA 325 has 3 channels, that's a huge advantage over the STR if used in your HT set up. For 2 channel use only, if you really want to over kill it with a 2 chanel amp, you may want to consider the Bryston 4B SST3 as a viable alternative to the STR too.

Nice looking Bryston amp.

 

[Verdinut]

I would also add that the rated voltage of a 200 W amp is going to be 1.414X that of the 100 W amp, all else being equal. So even based on the scenario when a tweeter is damaged by a badly clipped signal, a 100 W amp has lower odds because one would hear the warning sign, i.e. audible distortions from clipping much sooner and at a lower voltage, i.e. lower current. Again, I am not drawing conclusion, just saying let's not generalize, as it truly depends, on many things.

With audible distortions from clipping, it may well be too late. Damage is most likely done to the tweeter.

 

[Verdinut]

The odds for the more powerful amp are that it would damage the woofer and mid-range drivers if they are driven beyond their x-max and power handling capacities, and quite possibly without any damage occuring to the tweeter because it is operating within its limits without any clipping.

 

[PENG]

With audible distortions from clipping, it' may well be too late. Damage is most likely done to the tweeter.

No, not if you turn it down soon enough. Unlike large spikes, heat takes time to do damage.

 

[Cjamrr]

I have the demo Anthem MCA325 Amp connected to my system. I’m going to give it to 2 weeks to decide if this is the one to get. The stereo shop will bring the STR in 1 week to do a comparison.

 

[lovinthehd]

I have the demo Anthem MCA325 Amp connected to my system. I’m going to give it to 2 weeks to decide if this is the one to get. The stereo shop will bring the STR in 1 week to do a comparison.

How is that comparison to be conducted/setup?