2 chambers, separate tuning

[AccordSiR87 2]

Has anyone ever had 2 boxes or separate chambers with 2 different tuning frequencies? ie. 2 subs, 1 box/chamber @ 26hz other @34hz. If so, can you explain your thoughts on how well it worked or didnt work for you. I was thinking about this option, but I am beginner enough to not consider all of the pros and cons in depth. Thanks for the input.

[CrownVic 15]

what are your goals?

I havent heard of this before but someone on hear will be able to help.

[AccordSiR87 2]

I dont really have any goals with this concept. I was just strictly entertaining my imagination. Simply just talking it over at this point.

[///M5 2,833]

If you want unusual cancellation at frequencies go for it.

[AccordSiR87 2]

If you want unusual cancellation at frequencies go for it.

Thank you for such a well explained contribution. Could you please elaborate a little further on your suggestion?

[Impious 1,476]

You're idea wouldn't really be the best way to go about things.

If you were trying to increase output over a given bandwidth, you're best option would be to go with a properly designed (i.e. not a prefab) bandpass enclosure.

But without knowing what you were trying to accomplish, it's hard to give any specific recommendations.

[AccordSiR87 2]

Theres not really anything i am trying to accomplish, especially with this idea. The thought just came to mind so I decided to see if anyone had tried it or could shed some insight on the design.

[altoncustomtech 773]

The reason it won't work is because in a ported enclosure the subs have a "group delay" which is kind of like the idea behind time alignment (VERY LOOSELY BASED COMPARISON). The sound wave from the speaker is slightly out of sync with the wave of the input signal. The group delay changes with the diffrent design parameters of the enclosure, one of them being the enclosure tuning. If you were to build a box with seperate chambers tuned to different frequencies it could and most likely would cause cancellations (it would be like when two speakers playing the same frequency are wired out of phase, they move but you hear little to nothing) at frequencies that no one could possibly guess. That is a bad thing for MANY MANY reasons.

Like it was stated, if you had a goal behind trying that kind of design, we could help you find another more productive way to achieve that goal. Otherwise that is about the simplest way I could think of to explain one of the main reasons it won't work.

[blue fury 3]

Like this?

[jcarter1885 995]

Like this?

Thats what I was thinking of when I first read this but he wants one box and two different subs (each sub playing a ported to a different frequency. Basically like a dual ported enclosure but with a divided chamber, one side tuned to 26Hz and the other side tuned to 34hz if Im reading it right.

[AccordSiR87 2]

The reason it won't work is because in a ported enclosure the subs have a "group delay" which is kind of like the idea behind time alignment (VERY LOOSELY BASED COMPARISON). The sound wave from the speaker is slightly out of sync with the wave of the input signal. The group delay changes with the diffrent design parameters of the enclosure, one of them being the enclosure tuning. If you were to build a box with seperate chambers tuned to different frequencies it could and most likely would cause cancellations (it would be like when two speakers playing the same frequency are wired out of phase, they move but you hear little to nothing) at frequencies that no one could possibly guess. That is a bad thing for MANY MANY reasons.....

Thank you Alton for explaining. This was one of the considerations I began to think of, but would the 'canceled' freqs need to be completely out of phase for the cancellation to occur? I guess there could exist varying degrees of cancellation until which point the note would completely canceled itself out. I had just imagined that if indeed the freq needed to be 180 out of phase that the chances of that exact event where not very likely within a small space.

Like this?

I don't think that is what I completely had in mind. But, does that design have a specific name I can go try to read about? It is interesting.

Thats what I was thinking of when I first read this but he wants one box and two different subs (each sub playing a ported to a different frequency. Basically like a dual ported enclosure but with a divided chamber, one side tuned to 26Hz and the other side tuned to 34hz if Im reading it right.

Yes, thats what I was thinking of.

[blue fury 3]

That design I posted is a 6th order bandpass.

[///M5 2,833]

Cancellation occurs whenever any frequency isn't 100% in phase. The levels vary with degrees out of phase, but you will have serious anomalies.

If you have no goals for the idea then generically speaking it makes no sense. If you have a goal in mind, then there is another way to do this.

[altoncustomtech 773]

Thank you Alton for explaining. This was one of the considerations I began to think of, but would the 'canceled' freqs need to be completely out of phase for the cancellation to occur? I guess there could exist varying degrees of cancellation until which point the note would completely canceled itself out. I had just imagined that if indeed the freq needed to be 180 out of phase that the chances of that exact event where not very likely within a small space.

As M5 stated, when any frequency from two sources aren't 100% in phase it can cause some amount of cancellation. What plays into the equation then is the distance the waves travel and the reflections they encounter. This effect can be done in a room with a stereo set of speakers. By simply moving them and yourself around the room and listening to them in different positions you'll find that the sound can/will change depending on listening position and speaker position, and that's with everything the same! When putting a pair of speakers in two different boxes the anomalies are impossible to predict and would far outway any benefit of trying different tuning. As M5 and I said, there are better ways to go about getting the results that you're theorizing could be gained from doing this, all without the horrible results of this particular design.

[AccordSiR87 2]

Cancellation occurs whenever any frequency isn't 100% in phase. The levels vary with degrees out of phase, but you will have serious anomalies.......

Thanks for adding some clarification.

I understood that this idea was not popular, but I was not completely satisfied with why not. I appreciate you all helping me understand more in depth.