burning speakers?

[Mauskar]

How loud were you playing those? They are 8 ohms and in room has about 93 dB sensitivity. It will be loud with 1 watts applied.

volume is around 70-75%. Its loud but nothing like the showroom where i auditioned them. There is no real sound til about 50% volume.

Note this is after I used the speaker calibration tool that comes with Onkyo and lowered the gains slightly based on the polk tech's recommendation.

 

[Seth=L]

I can't imagine those RTi10s stay around 8 ohms.

 

[mtrycrafts]

volume is around 70-75%. Its loud but nothing like the showroom where i auditioned them. There is no real sound til about 50% volume.

Note this is after I used the speaker calibration tool that comes with Onkyo and lowered the gains slightly based on the polk tech's recommendation.

The problem with such volume guides, 50% and 75% is that it has no meaning at all Are there numbers on the display; what was it reading?

Now you say you calibrated your system. Do you have an SPL meter to check the calibration the Onkyo did? Where was the master volume control when this was occurring? How loud was the test tone in this condition?
What do you mean you reduced the gain? Where?

 

[mtrycrafts]

I can't imagine those RTi10s stay around 8 ohms.

Too bad there is not a good measurement of its impedance curve.
However, that Onkyo has a decent dynamic rating all the way down to 3 ohms, so it should be able to drive it up to the amp design limits and still produce volume at high levels.

 

[Seth=L]

Too bad there is not a good measurement of its impedance curve.
However, that Onkyo has a decent dynamic rating all the way down to 3 ohms, so it should be able to drive it up to the amp design limits and still produce volume at high levels.

I don't think that the Onkyo TX-SR605 would be stable with such a load, and would not be able to handle such low impedance as 3 ohms for more than a second or two without some fault occurring. Onkyo's published ratings on lower impedance loads may also inaccurate and/or assume optimal conditions (which I don't exactly know what that would be, maybe the protective circuitry removed?).

I am still thinking in the back of my mind maybe one of the speakers is the origination of the problem and maybe they should be returned in favor of another set of the same model.

Was the speaker wire gauge problem assessed? That could also cause some issues, but I would think such an issue would occur at the AVR and not the speaker.

 

[Mauskar]

The problem with such volume guides, 50% and 75% is that it has no meaning at all Are there numbers on the display; what was it reading?


Well the volume display goes from 0-100- I normally play music and watch movies at volume 50-75..


Now you say you calibrated your system. Do you have an SPL meter to check the calibration the Onkyo did? Where was the master volume control when this was occurring? How loud was the test tone in this condition?
What do you mean you reduced the gain? Where?

Don't have an SPL meter. Master Volume was set to 10- it didnt specify any volume in the manual. Not sure how loud the test tone was, so I will say that it was noticable enough to detect the speakers? I reduced gains based on the polk tech's recommendation- in the speaker menu, there is a calibration section and I reduced all speakers (fronts and subs) by -3db's.

 

[Mauskar]

Also, the volume display goes from 0-100- I normally play music and watch movies at volume 50-75..that was the answer to your first question

 

[TLS Guy]

I just don't buy that under powering caused his voice coils to overheat, even if they did. Under powering can blow tweeters but not woofers. The reason this comes about is that distortion products are harmonics of the fundamental. So if you clip a 1000Hz tone, the second harmonic will be 2000 hZ and the fourth 4000 Hz and so on. In this way too much power is sent to the tweeter and it can fry.

This used to be a big problem until the invention of ferro fluid. This is a magnetic fluid that is placed in the magnetic gap of tweeters in almost all speakers these days. This ferro fluid accomplishes two functions. It thermally couples the tweeter voice coil to the magnet pole pieces, so that power handling is very significantly increased. It lowers the free air resonance of the tweeter, and allows a lower crossover point, and avoids harshness by operating tweeters too close to resonance.

Woofers are damaged by overpowering, never under powering. Somehow you were driving those speakers too hard. Modern amps put a lot of power to the voice coils, especially the woofer. Just think for a moment how hot a 100 watt light bulb gets. If you put a sustained power of a 100 watts to a speaker voice coil it will get just as hot. The heating is time and power related, so the program material being played is a significant factor contributing to over heating. For instance electronic instruments and organs have notes that can be sustained over infinite periods of time, and are potentially loudspeaker killers if you are not careful.

I hope this helps you understand what is going on.

 

[Seth=L]

I just don't buy that under powering caused his voice coils to overheat, even if they did. Under powering can blow tweeters but not woofers. The reason this comes about is that distortion products are harmonics of the fundamental. So if you clip a 1000Hz tone, the second harmonic will be 2000 hZ and the fourth 4000 Hz and so on. In this way too much power is sent to the tweeter and it can fry.

This used to be a big problem until the invention of ferro fluid. This is a magnetic fluid that is placed in the magnetic gap of tweeters in almost all speakers these days. This ferro fluid accomplishes two functions. It thermally couples the tweeter voice coil to the magnet pole pieces, so that power handling is very significantly increased. It lowers the free air resonance of the tweeter, and allows a lower crossover point, and avoids harshness by operating tweeters too close to resonance.

Woofers are damaged by overpowering, never under powering. Somehow you were driving those speakers too hard. Modern amps put a lot of power to the voice coils, especially the woofer. Just think for a moment how hot a 100 watt light bulb gets. If you put a sustained power of a 100 watts to a speaker voice coil it will get just as hot. The heating is time and power related, so the program material being played is a significant factor contributing to over heating. For instance electronic instruments and organs have notes that can be sustained over infinite periods of time, and are potentially loudspeaker killers if you are not careful.

I hope this helps you understand what is going on.

I seriously doubt that the Onkyo TX-SR605 is capable of overpowering the RTi10s, have you seen the RTi10s?

Back to my theory that the speaker was just faulty from the factory, it seems no one is considering this, like it's impossible or something.

 

[TLS Guy]

I seriously doubt that the Onkyo TX-SR605 is capable of overpowering the RTi10s, have you seen the RTi10s?

Back to my theory that the speaker was just faulty from the factory, it seems no one is considering this, like it's impossible or something.

If you look at the beginning of my post, I doubted it too, but I've given up second guessing the ways people find to abuse an destroy speakers. Somehow they continue to find a way.

 

[mtrycrafts]

Don't have an SPL meter. Master Volume was set to 10- it didnt specify any volume in the manual. Not sure how loud the test tone was, so I will say that it was noticable enough to detect the speakers? I reduced gains based on the polk tech's recommendation- in the speaker menu, there is a calibration section and I reduced all speakers (fronts and subs) by -3db's.

OK, so that -3 dB was in the trim pots which would reduce the volume as well which might be compensated by increasing the volume control asking for more power, back to the beginning.

If the receiver was calibrated with the master volume at -10, that may have been too high or not. On some THX receivers, 0 is where it is calibrated but the control can also go to + 15 or +18. this is why I think the -10 may have been on the hot side.
Your levels of -50 and -75 seems about right although that is far from -10 that would be your so called reference level. So you never got even close to that.

 

[Seth=L]

I am also pretty certain that underpowering can destroy any type of dynamic compression driver if sustained long enough.

 

[TLS Guy]

I am also pretty certain that underpowering can destroy any type of dynamic compression driver if sustained long enough.

No it won't. That's folk lore. You see it all the time, but it's bunk. Tweeters yes, but even these days that is very rare. It was a problem before ferrofluid in the voice coil tweeter gaps.

One thing that contributed to the myth is that some older amps had no DC speaker protection. Some of those when overloaded would produce DC offset associated with the overload. That condition was a speaker fryer. No modern receiver is going to do that.

 

[PENG]

No it won't. That's folk lore. You see it all the time, but it's bunk. Tweeters yes, but even these days that is very rare. It was a problem before ferrofluid in the voice coil tweeter gaps.

One thing that contributed to the myth is that some older amps had no DC speaker protection. Some of those when overloaded would produce DC offset associated with the overload. That condition was a speaker fryer. No modern receiver is going to do that.

I believe buckeyeFan1 measured the resistance of the RTi10 before with a multimeter. Those meters can only measure resistance, i.e. d.c. resistance, but not impedance. If I remember correctly, he got 4 ohms, so I would agree with you that it will be very difficult for an underpowered receiver to blow the woofers in the RTi10 if they in fact offers 4 ohms even to a d.c. voltage. There just isn't enough d.c. resulted from the distorted/clipped output voltage to burnt those heavy voice coils.

 

[TLS Guy]

I believe buckeyeFan1 measured the resistance of the RTi10 before with a multimeter. Those meters can only measure resistance, i.e. d.c. resistance, but not impedance. If I remember correctly, he got 4 ohms, so I would agree with you that it will be very difficult for an underpowered receiver to blow the woofers in the RTi10 if they in fact offers 4 ohms even to a d.c. voltage. There just isn't enough d.c. resulted from the distorted/clipped output voltage to burnt those heavy voice coils.

I just don't believe any current amp or receiver will produce any significant DC offset. The damage comes from the distortion products, as I explained yesterday, that will be in the tweeter range. There could conceivably be a problem for certain mid ranges in three ways, but that I think is unlikely. When speakers are blown, it is nearly always overpowering and not under powering.

The problem is that any speakers power rating is bound to be approximate, and related to average program material. There is always the problem of unusual program material.

 

[PENG]

I just don't believe any current amp or receiver will produce any significant DC offset. The damage comes from the distortion products, as I explained yesterday, that will be in the tweeter range. There could conceivably be a problem for certain mid ranges in three ways, but that I think is unlikely. When speakers are blown, it is nearly always overpowering and not under powering.

My goodness, I was only trying to agree with you! I did not say there is any offset did I? Even if I was not totally clear I definitely did not imply any such offset would be significant. Okay let me try and clarify my point, I meant to say even (not that there is) if there is d.c. involved say due to a little bit of offset, I doubt an underpowered amp would be able to deliver enough current to burnt the woofers that reportedly (could be wrong) has a d.c. resistance of 4 ohms. That's all I was trying to say.

Again, I agreed to your point about the high order odd harmonics in a clipped signal that would potentially damage the tweeter but not the woofer.

 

[TLS Guy]

My goodness, I was only trying to agree with you! I did not say there is any offset did I? Even if I was not totally clear I definitely did not imply any such offset would be significant. Okay let me try and clarify my point, I meant to say even (not that there is) if there is d.c. involved say due to a little bit of offset, I doubt an underpowered amp would be able to deliver enough current to burnt the woofers that reportedly (could be wrong) has a d.c. resistance of 4 ohms. That's all I was trying to say.

Again, I agreed to your point about the high order odd harmonics in a clipped signal that would potentially damage the tweeter but not the woofer.

I don't know why you think we are so far apart. I was just questioning the DC produced by distortion. I agree you can clip so hard that you produce a square wave. You could if you wanted regard the anti nodes of the square wave as DC. However it would be of short duration with rapid changes of polarity. So there would be a lot of back EMF generated by the voice coil of the woofer. This is not the sort of thing that would take down a voice coil. However the rapid rise and fall of the waveform is made of the HF harmonics, and that is the tweeter destroyer. After all it is the the nice sharp corners of a square wave produced by an amp on a scope fed a square wave, that is one of the best guides to its HF performance.

The only DC I'm aware of at over drive would be DC offset from the direct coupled power transistors, and we have already had that discussion.

 

[PENG]

The only DC I'm aware of at over drive would be DC offset from the direct coupled power transistors, and we have already had that discussion.

I only said even if, in order to make a point, independent of yours. I guess we are both familiar with Fourier analysis and how amps work, and there is no disagreement here at all!!

Back to the OP's question, it is unlikely that the 605 has enough power to damage the RTi10's woofers but it may be capable of damaging the tweeters, or, like Seth said the speaker might have a defect in it to begin with.

 

[Soundman]

That dont sound good,seems to me to be a design flaw in the speakers wiring or xover,overpowering/underpowering issues aside i would think for saftey reasons any reputible manufacturer woud take these issues into consideration durring the design process.

[/IMG]

If this is speaker burn in, count me out! BTW, love the pic.

 

[krzywica]

I have to admit JG, I never got the honor of smelling the "new speaker burn" with mine...

I think he is referring to the little bit of excess flux that is sometimes prevalent in new electronics. And sometimes when used for the first time it burns off and gives off that "new speaker smell". However this is much more common with, say, an amp and not speakers. lol.