Cone Excursion Exceeding

[Tarun Nigam]

Hi folks, more inputs please.

 

[AudiOhm]

What are your crossover frequencies?

How did you calculate the box volume, port width and length?

Did you add internal bracing and insulation?

Ohms

You did not respond to my earlier questions.

This information will help us help you...

Ohms

 

[fpitas]

Making the box smaller will help limit excursion to some degree, although two things will happen: the bass extension won't be as good, and if you tune the port higher you'll be in more danger from low bass causing over-excursion.

 

[Prana Ferox]

The reality is that the DC130A-8 will hit xMax at 70-80hz at ~10 watts. Either that's good enough for you or it's not, there's not much box tuning can do there. The Dayton DC series are 'classic' woofers which aren't very sophisticated and have old-school specs including xmax, and this is what they can do. The 5 1/4" is good for fairly small speakers with fairly high rolloff, for nearfield listening, and the bass probably reinforced by having the speaker on a bookshelf or other flat surface near a wall.

 

[fineMen]

Thanks for appreciating FineMen, Can you please elaborate more on how bass will reduce to 20W, I cannot see this from the graphs anywhere. The woofer are 40W RMS.

Again, easy. When listening to music, that consists of many 'frequencies' simultaneously. Each musical tone would bring with it a series of overtones. E/g that's the reason fo having a (western) tonal system, the just intonation and so forth. The overtones are 2, 3, 4 ... times the base tone.

That is especuially true for bass, as bass wouldn't be identifiable in the musical context at all, because human hearing can't dicriminate the tone by itself, but uses the overtone series (nearly) alone ... The lowest tone (41Hz) of my bass guitar(s) is accompanied by a first overtone (82Hz) that is 6dB stronger (!!) than the base tone, and a second overtone (123Hz) that is as loud as the base tone. That is NOT distortion, but originates in the mechanical properties of the instrument and is actually highly appreciated.

So, feed the bass range with all the power that the amplifier is able to deliver ... nothing left for the overtones ... clipping distortion ... no music anymore.

Estimate of thumb: from the 40 leave at least half for the basses overtones and other irrelevant content, and you get to 20.

Anyway, all those calculations are only estimates - I mean the enclosure simulation. With higher excursion the f-speaker will change, Vas will change, Qms, Qe will change and so forth, let alone density etc changes to the air due to ... weather!

You're too much focused on a singled out, tiny bit of speaker optimization With regular use you won't destroy the speaker.

 

[fineMen]

Hi folks, more inputs please.

Not necessary, me thinks. It doesn't take a new design, but it takes some care in using the speaker. Most of all speakers around are designed with a power spec that is way too high for the bass range, if the latter was pushed alone with the watts specified. And now think of how often a speaker' woofer is blown off. You better come to understand the wider context, the simulation tricked you.

You did not respond to my earlier questions.

This information will help us help you...

Ohms

I think x-over is irrelevant here anyway.

Making the box smaller will help limit excursion to some degree, ..

Simply put, no. It would only throw away efficiency. You would better destroy that precious amp power in an electrical resistor in front of that woofer.

The Dayton DC series are 'classic' woofers which aren't very sophisticated ...

As said above, the "overexcursion" is a common feature of nearly all loudspeaker around.

 

[fpitas]

Simply put, no. It would only throw away efficiency. You would better destroy that precious amp power in an electrical resistor in front of that woofer.

I agree, but the subject (I think?) was over-excursion.

In any event I think the exercise is pointless. Be careful with the bass, or use a larger driver are the sensible choices.

 

[fineMen]

I agree, but the subject (I think?) was over-excursion.

You can make anything you want from my input. Once it is understood that music has overtones, the case is closed. Maybe this helps further:

Let's think of a speaker that is excursion restricted to what the amp delivers, e/g an amp of 100Watts and a speaker/enclosure combination that restricts the woofers excursion so that it would remain "linear" -- whatever that means anyway, with that 100Watts.

Now the system is fed with a real musical signal originating in a bass guitar, base tone 60Hz (most demanding for common ported boxes) plus overtones 120Hz and 180Hz an 240Hz and so on. Let's assume the series of base and overtones has a quite realistic distribution of levels as such: 60Hz : +/-0dB, 120Hz: +3dB, 180Hz: +/-0dB, 240: -6dB

The overtones consume more than three times (!!) the base tone's portion of the amplifier power, that is the +3dB at 120Hz (+3dB: double) plus an additional 0dB (equal to base tone) at 180Hz and so forth.

In order to keep the amp in non-clipping mode, within its specs, the base tone (60Hz) would consume 25Watts, and the overtones (120Hz, 180Hz, ...) 75Watts. With that 25Watts for the base tone one would only use 1/4 of power, while it was designed to be limited at 100Watts, so half of the available excursion is wasted (a 1/4 power == -6dB == half excursion).

Please replicate the calculations by your own. That is why "overexcursion" is actually desired, except one has less briliant people at the power controls.

Before the expected doubt comes up: positively and specifically the overtones' spectrum looks like that. ( I have a bass guitar (a) and evaluated bass heavy synthetic music also (b). Side note: that is why a smaller portion of harmonic distortion (HD2, HD3 ...) is nearly always masked by the music. But not the intermodulation distortion. )

 

[fpitas]

You can make anything you want from my input. Once it is understood that music has overtones, the case is closed. Maybe this helps further:

Let's think of a speaker that is excursion restricted to what the amp delivers, e/g an amp of 100Watts and a speaker/enclosure combination that restricts the woofers excursion so that it would remain "linear" -- whatever that means anyway, with that 100Watts.

Now the system is fed with a real musical signal originating in a bass guitar, base tone 60Hz (most demanding for common ported boxes) plus overtones 120Hz and 180Hz an 240Hz and so on. Let's assume the series of base and overtones has a quite realistic distribution of levels as such: 60Hz : +/-0dB, 120Hz: +3dB, 180Hz: +/-0dB, 240: -6dB

The overtones consume more than three times (!!) the base tone's portion of the amplifier power, that is the +3dB at 120Hz (+3dB: double) plus an additional 0dB (equal to base tone) at 180Hz and so forth.

In order to keep the amp in non-clipping mode, within its specs, the base tone (60Hz) would consume 25Watts, and the overtones (120Hz, 180Hz, ...) 75Watts. With that 25Watts for the base tone one would only use 1/4 of power, while it was designed to be limited at 100Watts, so half of the available excursion is wasted (a 1/4 power == -6dB == half excursion).

Please replicate the calculations by your own. That is why "overexcursion" is actually needed, except one has less briliant people at the power control.

I believe you. In any event, the OP is the one to convince

 

[AudiOhm]

The reason for the questions was to determine the skills, knowledge and tools used to design the speakers.

Just placing drivers in a box is not speaker building and can lead to a world of trouble...

Ohms

 

[audiofooled]

You can make anything you want from my input. Once it is understood that music has overtones, the case is closed. Maybe this helps further:

Let's think of a speaker that is excursion restricted to what the amp delivers, e/g an amp of 100Watts and a speaker/enclosure combination that restricts the woofers excursion so that it would remain "linear" -- whatever that means anyway, with that 100Watts.

Now the system is fed with a real musical signal originating in a bass guitar, base tone 60Hz (most demanding for common ported boxes) plus overtones 120Hz and 180Hz an 240Hz and so on. Let's assume the series of base and overtones has a quite realistic distribution of levels as such: 60Hz : +/-0dB, 120Hz: +3dB, 180Hz: +/-0dB, 240: -6dB

The overtones consume more than three times (!!) the base tone's portion of the amplifier power, that is the +3dB at 120Hz (+3dB: double) plus an additional 0dB (equal to base tone) at 180Hz and so forth.

In order to keep the amp in non-clipping mode, within its specs, the base tone (60Hz) would consume 25Watts, and the overtones (120Hz, 180Hz, ...) 75Watts. With that 25Watts for the base tone one would only use 1/4 of power, while it was designed to be limited at 100Watts, so half of the available excursion is wasted (a 1/4 power == -6dB == half excursion).

Please replicate the calculations by your own. That is why "overexcursion" is actually desired, except one has less briliant people at the power controls.

Before the expected doubt comes up: positively and specifically the overtones' spectrum looks like that. ( I have a bass guitar (a) and evaluated bass heavy synthetic music also (b). Side note: that is why a smaller portion of harmonic distortion (HD2, HD3 ...) is nearly always masked by the music. But not the intermodulation distortion. )

 

[Eetu]

As mentioned before, you should flush mount the tweeter and the woofer. You can see from the shadow that the tweeter is not flush mounted. Even .5mm makes a difference.

 

[Kimbrough Xu]

This is why I'd play around with a low shelf filter and/or a limiter rather than just kill off low frequencies altogether with a HPF. If you get a subwoofer, then using a HPF is a better idea.

But if I need a subwoofer, then I can also keep the sub frequency from the stereo speakers.

 

[fieldcar]

But if I need a subwoofer, then I can also keep the sub frequency from the stereo speakers.

Assuming by "from" you mean "high passed" in regards to the L&R speakers, then that's correct!

Most conventional wisdom is that if you keep your L&R passing full range with a subwoofer, you'll get exaggerated summing and cancellation via room mode interaction. This often sounds like some notes are exaggerated, and others are missing and hollow. With OP's 1-way speakers, you'll also get over-excursion / intermodulation distortion that will cap your listening level if a HPF isn't used. The only way you can keep your L+R channels full range is good room correction and having well designed full range speakers that can handle it, and even then, you will still loose headroom before distortion takes over.