Yeah, no. Badly designed crossovers can certainly sound bad, but the rest of this doesn't make sense. I'll go through it.
That's not how that works. Inductors are used mostly as low pass filters in passive crossovers. The value corresponds with the T-S parameters of the driver, the desired crossover corner frequency, etc etc.
Amps add crossover distortion. If you mean the components in the crossover adding distortion, then sure, poor quality ferrous core inductors and inappropriate capacitors can... But otherwise, no. Chances are good it'd be swamped by the distortion inherent in the actual drivers though - exceptional drivers have 0.1% distortion.
All filters do this because all filters ring, and all non-FIR filters rotate phase. Each pole rotates phase 90 degrees. Thankfully, we are almost entirely immune to phase rotation unless truly pathological. But if this concerns you, use a FIR DSP crossover where phase and magnitude can be adjusted separately, or do what PSI does and cascade all-pass filters after an analog active crossover to linearize the phase.
Non sequitur. Unrelated.
No. In fact, simple crossovers are usually worse in most respects! You end up with drivers playing stuff at significant level that they really don't want to, along with a wide stopband - which means the drivers will interfere with each other more. This shows up in off-axis measurements - as well as on axis if it's bad enough!
Yes. Active crossovers are substantially better in all regards. The crossover doesn't rely on the driver's electromechanical qualities, the amp is connected directly to the driver, you can do both positive and negative EQ to correct response, you can correct for filter phase rotation (whether or not this is necessary is another story), you can integrate driver protection limiters. I see little reason these days to use a passive crossover if you don't need to.
Or use the 8 ohm hookup and don't bother with anything else. You get the same power to the speakers for free.
Sure but if your speakers have low impedance dips, and your amp gets unstable into low impedances.... the sound will degrade.
When you have an amp rated at 100W +, running into your nominal 4 ohm speakers, with a 1.6ohm minimum, and it runs things without any trouble at reference levels... but doesn't sound great... then you replace it with an amp rated at 2ohm - and suddenly the sound totally clears up, and sounds the way your system should.... My suspicion is a stability issue.
So are you speaking of some undefined speaker? Or are trying to answer the OPs question? He has a choice of a 2 ohm load or 8 ohms. His amp doesn't like 2 ohms apparently. Your choices are add a resistor wasting roughly half the power or use 8 ohm connections getting probably half the power or a little less depending upon the amp. The amp sees 4 ohms half being wasted or sees 8 ohm producing half the power without the waste.
Heck if there is an existing 8ohm connection (yes I missed that!) - then I would absolutely use that and move on!
He has two voice coils. Paralleled as 2 ohms or series connected as 8 ohms. His amp is apparently okay at 4 ohms, not at 2 ohms.
I like your points, i was just looking at the situation from a theoretical point of view : pros and cons of simple and complex crossovers into low impedance loads, and effects on amp stability. Can't find much about it on the other forums. Thanks !
Did you measure the Integra to ensure it was not clipping? And look for oscillations or other signs of instability? That sounds like a power limitation, not a stability issue. "Lacking in current" is a power limitation, not a stability issue. I do not know where you get your power numbers, but bass takes much more power than midrange, is very dependent upon the source material, and peaks can easily be 50 to 100 times higher in power than the average level. Clipping on peaks will make he sound harsh and so forth.
Clipping is a very obvious and distinctive (horrible!!!) sound signature - this sounded OK... average person would probably say the setup sounded fine - but having run the setup with other amps/AVR's I recognised it could sound better - and could identify aspects that were less than ideal.
No, not necessarily. It is often fleeting and imparts just a harsh overtone or buzz to the sound. It is often perceived as simply making the sound "less clear" or "foggy".
OK.
Peaks may clip without indicators -- it depends upon how the clipping indicators are designed. While I do not know the specifics of Crown's current designs, IME they (Crown, and pro amps in general) are designed to light when clipping is more sustained than for very brief periods like a cycle or three. Note that the peak to average ratio of music is around 17 dB, a factor of 50, so at 4 W the amp could be outputting peaks of 200 W. For movies, the ratio is higher (as much as 100x), probably due to explosions and such (where clipping might not be noticed anyway).
AVRs are notoriously overspec'd, especially since the amplifier rules changed many years ago. And see comment above about peak to average levels.
The signal coming out of the AVR includes all frequencies above the sub and LFE crossover (if you have a sub), typically 80 Hz. Look at equal loudness curves to observe how much of the power may be in the bass region even above the crossover. Clipping is most often perceived in the midrange, as it affects all frequencies, and midrange frequencies are easiest for us to hear. Among the biggest problems of clipping, which is usually due to bass signals, is that average power increases significantly (due to the change in waveshape from sinusoidal to square'ish) and HF energy increases (destroying tweeters). This article discusses clipping in a bit more detail:
www.audiosciencereview.com
That does not mean lower-power amps are unstable, which implies oscillation. Instability leads to oscillation leads to amplifiers shutting down and/or blowing up, often taking the speakers with them. Instabilities usually cause ringing and oscillation at very high frequency, where the feedback loop "opens" at the limit of the amplifier's bandwidth. Most of the time we do not hear anything; the amp and/or speakers just die when the amp goes unstable.
That is one of the key indications of clipping. Severe harshness occurs when clipping is severe, but audible degradation can occur well before that point. It can be a rather subtle effect before becoming overtly noticeable. I tend to use "harshness" for what you describe as "congestion".
Measurements could end this argument but you do not need tools to hear clipping. Alternate amps provided more power. Your definition of "unstable" clearly differs from mine (as an engineer and audiophile), as does your diagnosis of the root cause, and equally clearly nothing I can say will convince you otherwise so I'll drop this.
I read "unstable" as "oscillating or near to it", not as "running out of power"...
It's not a topic often discussed in other forums. Unless they have a loudspeaker and crossover design forum.
Any added resistance would also clobber the benefit of the damping factor of the amplifier as well, possibly resulting in boomy flabby bass.
I just remembered that Benchmark has a discussion on series resistance (i.e. high damping factor) and the change in frequency response. There is a calculator that estimates that frequency response variation expected for a given amp and speaker combo. It doesn't take the detailed impedance vs. frequency of a given speaker into account, but it does give ranges. And, to be clear the resistor values you would use to get a higher impedance make the details rather irrelevant. Adding a 6 Ohm resistor is like using 1500 feet of 13-gauge speaker cable, and the resulting frequency response errors are very large (>>5dB) depending on the actual impedance of your sub driver...
