It is impossible to seal a box electronically !
Loudspeakers are in no case minimum phase !
That's not elaborating, nor coming with any arguments, but just repeating the same statement over again.
Which brings zero constructive value to any discussion.
I am mostly confused why you keep doing that?
Sure, you have the right to have your opinion, it's only not really convincing that way, especially after previous discussions and information that have been shared from quite some skilled, knowledgeable, experienced and respected members.
Besides the fact that for certain subjects, having an opinion isn't really relevant or even a question to begin with.
But that's a whole different story all together.
So let me rephrase the question, why are you not willing to share some more information on your thoughts?
Hello. I am going to build 2 sealed bass cabinets with 2x 10" Seas drivers. They should have 25-40 liters each. What is best solution; seperate chambers or back to back ( vibrations canselling) Today my speakers are Mirage OM6 with dual 8" back to back. The other solution is to put the one in the front high in the cabinet and the one in the back low in the cabinet like Mirage M1. Should I separete the woofers in each chamber or should the play in the same? Could the cabinet be smaller when they share chamber?
@Norlenning It depends on the amplification you wil use if you connect the woofers parralel they may share the same volume, but it must be twice the volume what is needed for 1 woofer.
2x4 ohm woofers in parallel give a 2 ohm load on the amp, look at the specs of the amp if it can handle 2ohm load.
If you use a 2 channel amp for example 2x500w i think its better to give each woofer his one sealed enclosure, for if the amps have not exact the same output.
I use a Hypex FA501 amp in parallel for powering 2 scan speak discovery 12 inch woofers (its a dual opposed subwoofer), the FA501 can have a 2ohm load.
If the driver needs 40 liter you can make it 20% smaller and adding polyfill , the wool make the woofer behave like its in a 20% bigger space.
2x4 ohm woofers in parallel give a 2 ohm load on the amp, look at the specs of the amp if it can handle 2ohm load.
If you use a 2 channel amp for example 2x500w i think its better to give each woofer his one sealed enclosure, for if the amps have not exact the same output.
I use a Hypex FA501 amp in parallel for powering 2 scan speak discovery 12 inch woofers (its a dual opposed subwoofer), the FA501 can have a 2ohm load.
If the driver needs 40 liter you can make it 20% smaller and adding polyfill , the wool make the woofer behave like its in a 20% bigger space.
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Yes, I think you're right...that the pre-echo is low-passed induced due to not having any commentary xover offset.
i watch the dip in the sub's impulse response before it's peak go away when the rest of the speaker is added.
Here's a quick example with just the next driver up, covering 100-250Hz, when added to the sub.
Red sub, blue woofer, and black their summation...if not obvious to others.
The black summation impulse...the left side dip is already a little less than the right side dip....with just the addition of the 100-250Hz woofer.
As sections are added, mid, then HF, VHF....I watch the left side dip melt into flatness.
Thanks for pointing out that the look of the slopes on the transfer function I posted, didn't seem right....
Yes, the low pass should be 96dB oct, but I can see it was falling short of that.
I'm learning a new FIR generator and goofed..
Here's sub redone...same 96 dB/oct lin lpf, and same 20Hz IIR bu3 hpf
Have to retune speaker and check for further goofs...only got to adding woofer so far, like above example.
Can/will, show full speaker with sub for impulse when done.
@Norlenning look in winisd or speakerboxlite or other speaker design software what volume the driver needs for a qtc arround 0.707.
You can also see the power handling and xmax.
You can also see the power handling and xmax.
One key moment for me re audio was being given the opportunity to sit by the conductor for the BBC Philharmonic Orchestra during rehearsals just in case one of the mics needed adjustment. It's as much the feeling of the performance e as the sound. Another inspiration is Evelyn Glennie
https://en.m.wikipedia.org/wiki/Evelyn_Glennie
I really believe we must have some kind of miscommunication or misunderstanding about the term "Minimum Phase".
To demonstrate the point in a practical way, I took the measured response of a driver I have, Satori MW16TX-4. I measured the frequency response, capturing both magnitude and phase.
Next I used analog filter elements, which are minimum phase, to mimic the driver's response as closely as I could. The resulting filter is made up entirely of minimum phase elements.
If we compare the magnitude and phase response of the driver and the filter, it is clear that they are very close, and the difference is insignificant for any kind of design purpose. If the driver had a phase response which was drastically different than the filter phase, we could conclude that the driver was not minimum phase. But this is not the case. The driver follows the minimum phase response very closely. So from a practical standpoint, this driver is minimum phase.
Perhaps you mean something different by the term "minimum phase" ?
From sections 7.1 and 7.2 of the original Oppenheim & Schafer book, in the Fourier Transform of a real, causal, stable minimum-phase sequence, the logarithm of the magnitude, and the unwrapped phase angle, will form a Hilbert Transform pair. Logarithm has to be base "e" and phase has to be in radians. There may be a gain term that depends upon the scaling applied to the Fourier Transform.
I have a pair of 3-way towers with double woofers. Neardield measurement tells that vertical standing wave in the box makes difference around 800Hz. Insignificant in 3-way...
Thx, a powerful song, both music and message....one that I hadn't heard before.
I have a pair of speakers I've heard Metallica used for drum monitors...gonna pull them out and give it a listen.
I'm nowhere as knowledgeable as most here but I've been reading a lot and chose to build sealed subs for my living room HT/stereo set.
Here an RTA with peaks values from a movie at elevated volume while maintaining an exceptionally clean and fast sound. I see a dip in the low teens but would I really miss those frequencies? What movies really have meaningful content that low these days? I already get the impression that some music and movies have exaggerated LFE in the 30Hz region.
Here an RTA with peaks values from a movie at elevated volume while maintaining an exceptionally clean and fast sound. I see a dip in the low teens but would I really miss those frequencies? What movies really have meaningful content that low these days? I already get the impression that some music and movies have exaggerated LFE in the 30Hz region.
Ok, following up on info i said I'd provide in #405.....in discussion of pre-echo potential.
Here are the impulse responses from each section of a 5-way speaker.
All are acoustic measurements, made close to the speaker indoors.
Each clearly has a lot of dip below zero before it's impulse peak. (and after)
Xovers @100, 250, 750, & 4000Hz...all linear phase 96dB/oct.
Here is the full speaker's impulse in Black, iow all impulses summed together. (along with the sub's impulse again, for reference),
System impulse kinda says it all, i think..
Here are the impulse responses from each section of a 5-way speaker.
All are acoustic measurements, made close to the speaker indoors.
Each clearly has a lot of dip below zero before it's impulse peak. (and after)
Xovers @100, 250, 750, & 4000Hz...all linear phase 96dB/oct.
Here is the full speaker's impulse in Black, iow all impulses summed together. (along with the sub's impulse again, for reference),
System impulse kinda says it all, i think..
Well. my undergrad math minor is long forgotten....
So nowadays my definitions tend to rest on "what does a term mean, and what can I do with it".
For me, minimum phase means I can successfully EQ the dang thing.
That I can use IIR EQs to correct frequency magnitude response, and that will simultaneously correct phase......
and that the corrections hold up spatially.
If so, it's min phase. If not so, it's not min phase.
Works for me ! 😀