So I got a question as I think there's either something wrong with my measurements or my understanding of crossovers and alignment.
I currently use 2 Jbell SS15 subs with an MKH 130 on top and Spl runt copies on top per side.
Sadly I can currently only measure in room.
My steps were:
1. Set main system target
2. Set individual targets for the individual speakers
3. Set crossovers to follow my desired targets.
4. Now some weird things happen:
I used asymmetrical crossovers. for example SS15 -> low pass 85hz 18db Butterworth to meet the MKH130 which was high passed at 80hz Linkwitz Riley 24db
5. so far so good, they meet my target...
6. I used sub align to verify the point where I should place my mic for an even distribution of phase shift. (but in a 5m long room, there wasn't very much difference)
7. weird thing is: they time and phase align perfectly without using any delay.... did my crossovers shift the phase in a certain way so that the 2 speakers got time and phase aligned by simply using specific crossovers? or am I measuring it wrong.
9. After that I tried using different crossover settings and now the mkh130 needs some delay to match phase with the SS15.
I also did a A/B listening test and couldn't really tell any difference, but also the room is pretty bad, without any acoustic treatment for bass.
My main question is: could it possibly be that those specific crossover settings just "work" without any delay or should I try measuring the whole thing outside to verify?
Thanks in advance
Johannes
I currently use 2 Jbell SS15 subs with an MKH 130 on top and Spl runt copies on top per side.
Sadly I can currently only measure in room.
My steps were:
1. Set main system target
2. Set individual targets for the individual speakers
3. Set crossovers to follow my desired targets.
4. Now some weird things happen:
I used asymmetrical crossovers. for example SS15 -> low pass 85hz 18db Butterworth to meet the MKH130 which was high passed at 80hz Linkwitz Riley 24db
5. so far so good, they meet my target...
6. I used sub align to verify the point where I should place my mic for an even distribution of phase shift. (but in a 5m long room, there wasn't very much difference)
7. weird thing is: they time and phase align perfectly without using any delay.... did my crossovers shift the phase in a certain way so that the 2 speakers got time and phase aligned by simply using specific crossovers? or am I measuring it wrong.
9. After that I tried using different crossover settings and now the mkh130 needs some delay to match phase with the SS15.
I also did a A/B listening test and couldn't really tell any difference, but also the room is pretty bad, without any acoustic treatment for bass.
My main question is: could it possibly be that those specific crossover settings just "work" without any delay or should I try measuring the whole thing outside to verify?
Thanks in advance
Johannes
Your specific crossover settings may "work" without any delay but still be a cycle off.
See if your method concurs with Merlijn Van Veen's:
https://www.merlijnvanveen.nl/en/st...gnment-the-foolproof-relative-absolute-method
See if your method concurs with Merlijn Van Veen's:
https://www.merlijnvanveen.nl/en/st...gnment-the-foolproof-relative-absolute-method
What do you mean by „a Cycle off“
Phase traces match perfectly, also Impulse response in REW peaks at the same time.
Phase traces match perfectly, also Impulse response in REW peaks at the same time.
On 360 degree cycle, one wavelength duration off could phase align without time alignment, I overlooked you had written time and phase aligned.
The difference in phase shifts between "different crossover settings" may be around 90 degrees per order, roughly 3.5ms at 80Hz difference between 18/24dB.
In bass reflex (phase inversion) enclosures the port output is lagging by one wave period from the upper response, the phase at the acoustic crossover of the Spl Runt copies would depend on the alignment, sealed or ported.
The difference in phase shifts between "different crossover settings" may be around 90 degrees per order, roughly 3.5ms at 80Hz difference between 18/24dB.
In bass reflex (phase inversion) enclosures the port output is lagging by one wave period from the upper response, the phase at the acoustic crossover of the Spl Runt copies would depend on the alignment, sealed or ported.
At 85Hz the steady state behaviour is significant, as it takes time to become aware of lower frequencies.
Alright thanks,
Additionally: as a General rule of thumb as merlijn van veen says its best to use lowest order crossovers as often as possible?
Additionally: as a General rule of thumb as merlijn van veen says its best to use lowest order crossovers as often as possible?
The merits of DSP are the possibility to have steep filters and move them along the Freq. axys. I don't see It useful to have two voices overlying for a large part,
On the other hand, relying on band-pass behaviour of a speaker and use low phase shift filters ( the speakers themselves make phase rotation along their pass band ) is the essential basic crossover technique.
This is true until the speakers meet their limits. First limit is a boundary! A room has 6 boundaries...
This is true until the speakers meet their limits. First limit is a boundary! A room has 6 boundaries...
Merlijn's implication is to use the order that results in an acoustic crossover of the desired order, the majority of the industry using 4th order crossovers with 24 dB per octave slopes.
From Merlijn Van Veen's article Subwoofer Alignment: The foolproof relative / absolute method
Which order to choose:
"The majority of the industry appears to have settled for 4th order crossovers ...with 24 dB per octave slopes....this constitutes 4th order acoustical crossovers which is the compound result of electronics in concert with the mechanical-acoustical properties of the loudspeakers themselves..However, the loudspeakers themselves come with natural "native" frequency roll-offs which define their operational range.
Figure 7 contains red arrows indicating actual 4th order, 24 dB per octave slopes. Notice that the 4th order electrical filters in concert with the natural roll-offs, produce slopes which are too steep in the frequency range of interest, for no good reason! That's why I encourage restraint with electronic filters and recommend to start with lower-order filters first.
Typically, 2nd order, this close to the natural roll-offs, works nicely while avoiding the unnecessary introduction of extra, unjustified, phase shift, inherent to higher-order filters, to a part of the frequency spectrum where most loudspeakers are already sluggish by design!"
Tapped horns don't exhibit "typical natural roll-offs" or phase response in the upper range, so lower orders may not "work nicely" ;^).
Alright thanks, is there any reason on why to try to get an acoustical Crossover of 24db per octave? Is it just a sweet spot where it just „works“?
Next week i‘m back at my system and can experiment a bit more.
If i for example use 12db per octave acoustical targets, what should i expect? or for example 36db or steeper targets?
Next week i‘m back at my system and can experiment a bit more.
If i for example use 12db per octave acoustical targets, what should i expect? or for example 36db or steeper targets?
Rather than trying to achieve a certain slope, you might try to deal with the issues using at least the minimum needed slope, but preferrably not steeper.
You can expect to hear badly reproduced vocals from a TH crossed at only 12dB per octave, and excessive excursion from the top cabinet causing intermodulation distortion.
24dB per octave is steep enough to avoid those problems, though out of band EQ is generally needed too.