Usually, we compensate impedance peaks in order to provide a coherent impedance for the frequency crossover to work properly.
Therefore, for a woofer with low x-over, it is obvious to compensate the speakers resonance peak.
I was wondering if it makes sense to compensate also the vent tube impedance peak? Does the vent still work with compensation? Will it result in a flatter phase response and higher sound quality?
Is there a chance to control better the frequencies below fsvent?
Many thanks!
Therefore, for a woofer with low x-over, it is obvious to compensate the speakers resonance peak.
I was wondering if it makes sense to compensate also the vent tube impedance peak? Does the vent still work with compensation? Will it result in a flatter phase response and higher sound quality?
Is there a chance to control better the frequencies below fsvent?
Many thanks!
No, you'd be simply spending for large unnecessary components, and stressing your amplifier for no benefit... some would disagree though, see the 'Elsinore" xover for an example
I have compensated the lower peak at times. Eg when crossing subs. Only if it makes a difference and sometimes it does. This may or may not mean the lowest of vented peaks, you need information to know whether it helps.
Compensating the peaks does not prevent the driver from doing its job. It shouldn't do anything to phase, assuming you are properly designing your crossover.
Compensating the peaks does not prevent the driver from doing its job. It shouldn't do anything to phase, assuming you are properly designing your crossover.
Impedance peak compensation can flatten the electrical phase (aka phase angle). Basically this creates an overall lower impedance response but smaller variations in phase angle. But needs very large (often impractical) value passive parts.
Active crossovers usually doesn't have impedance corrections and sounds better than passives (a can of worms have just spilled out), especially at low xo points. Draw your conclusion.
Active crossovers usually doesn't have impedance corrections and sounds better than passives (a can of worms have just spilled out), especially at low xo points. Draw your conclusion.
The Elsinore does not compensate the impedance peak of the vent.
I would guess that compensating that peak would eliminate the function of the vent. However, this would imply that it is possible to lower the effect of the vent - Im my eyes, an interesting option.
Clearly, components will cost something.
I am not asking if this makes sense. But what is the effect to the "control" below fs?
Best wishes
I would guess that compensating that peak would eliminate the function of the vent. However, this would imply that it is possible to lower the effect of the vent - Im my eyes, an interesting option.
Clearly, components will cost something.
I am not asking if this makes sense. But what is the effect to the "control" below fs?
Best wishes
The vent does not have a corresponding impedance peak. The tuning frequency of the vent is between the frequencies of the two peaks.
An impedance peak makes the woofer play louder at the frequency range of the peak, louder than expected when it would behave as a pure resistive load. It does not affect the acoustic performance of the vent.
An impedance peak makes the woofer play louder at the frequency range of the peak, louder than expected when it would behave as a pure resistive load. It does not affect the acoustic performance of the vent.
If the properties of the load impedance are critical to the amp, then why isn't this compensation just as important when not using a passive filter?
Make sure you fully simulate the power dissipation in any components used, it can be quite high.
I mean, a passive filter can create extreme electrical phase angles because of the impedance peaks and a filter close to it. Of course it can be compensated, but the total impedance will be lower.
It can be compensated for an active system too, but a good dimensioned box have far more amplifier-friendly impedance than with a passive filter (when uncompensated).
For example: a passive lowpass filter create an additional, unwanted 4dB peak around 100Hz and if you want to remove it passively, you need impedance correction with additional passive elements (with questionable power handling). So lame (in the light of active filtering), sorry.
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The driver has plenty of impedance variation without any components. Your idea that a crossover makes this worse is arbitrary and doesn't make sense.
Edit: (overpost edit)
Edit: (overpost edit)
Speaking in electronics generally, impedance compensation is nothing to be ashamed of. Your comments sound like audiophile rantings to me.
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As long as the peak frequency is far away from where the filter roll off kicks in, the impedance peak will not have a large effect on the filter transfer function.
Any impedance peak may have an effect on the "amplifier control", especially if the amplifier has a high output impedance. Impedance peaks go along with large phase angles, which may cause additional trouble to such amplifers. Depending on the amplifier, it may therefore be useful to compensate the lower impedance peak.
That said, the lower impedance peak of a bass reflex system occurs below the bass cut-off frequency, where the loudspeaker does not produce a lot of sound anyway. I therefore prefer to just put a high-pass filter (smallish capacitor) to the input of a "weak amplifier" in order to attenuate all sound below the bass cut-off of the loudspeaker, so the lower impedance peak is out of the game.
Any impedance peak may have an effect on the "amplifier control", especially if the amplifier has a high output impedance. Impedance peaks go along with large phase angles, which may cause additional trouble to such amplifers. Depending on the amplifier, it may therefore be useful to compensate the lower impedance peak.
That said, the lower impedance peak of a bass reflex system occurs below the bass cut-off frequency, where the loudspeaker does not produce a lot of sound anyway. I therefore prefer to just put a high-pass filter (smallish capacitor) to the input of a "weak amplifier" in order to attenuate all sound below the bass cut-off of the loudspeaker, so the lower impedance peak is out of the game.
That's your opinion. My opinion is that, a passive lowpass for bass duties makes things always worse on the electrical side, no matter what. It can be somewhat tamed with compensation, but that's it.
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Additionally, compensating the impedance peaks will reduce the speaker's efficiency because the impedance and the frequency magnitude will be lower at the same time.
No. The driver/loudspeaker sees the same drive voltage with or without the impedance compensation. It will therefore produce the same SPL, no matter if impedance compensation is applied or not.
Sorry you are wrong, it sees the same voltage that's right, but requires much more current because the lower impedance, and the spl stays the same or lower.
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Doesn't need. Or you compensate the impedance peaks by lifting the impedance to the top of the peaks?
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