I think it is very well possible, at least in closed boxes. The attached pdf gives some arguments.
There was a 70s box speaker that employed a small translucent plastic bucket as a mid-range enclosure. It was adhered to the baffle with silicon caulk and looked like it came from the food industry. The brand name of the speaker escapes me but I think it starts with an "R"...
Think of the bass enclosure as bass reflex and as a passive radiator.
The passive radiator (mid) is not designed to operate in that condition.
The mid-range will likely be forced to the extremes of its' mechanical excursion which is not optimal for either bass output or mid-range function.
Try it with a mid-range driver that you don't mind destroying.
The passive radiator (mid) is not designed to operate in that condition.
The mid-range will likely be forced to the extremes of its' mechanical excursion which is not optimal for either bass output or mid-range function.
Try it with a mid-range driver that you don't mind destroying.
I don't think destruction lies at hand. The mechanical compliance Cms and the total Rs (=Res + Rms), related to the cone area, are such that the moving cone hardly will reach extremes unless the woofer will also reach extreme amplitudes. But it will move and as such destroy good midrange reproduction. Still a no-no.
You want to use a closed back midrange and solve all your problems.
Open back midranges need the right size space behind them to ensure proper operation in the low end of their range. Excessively large space will depress this region. Not to mention that the acoustic and electrical interaction between the woofer and mid becomes pretty complicated.
Open back midranges need the right size space behind them to ensure proper operation in the low end of their range. Excessively large space will depress this region. Not to mention that the acoustic and electrical interaction between the woofer and mid becomes pretty complicated.
Indeed the small midrange moves around its resonance frequency due to the movement of the woofer. But to what extent is the midrange disturbed, and by what mechanism (FM modulation ?). Can you quantify the degree of disturbance ?
Monitor Audio stated for its MA 1 that they did not put the mid driver in a dedicated enclosure. I think the mid here is a B&W 5 or a 6 inch, the bass driver is the KEF B139. The MA1 is a vented design, though. Still curious to hear how this speaker sounds.
We could hypothesize… but local pressure variations as on the midrange cone in the box don’t relate to the woofer movement. Suffice to say Bl/xvar isn’t linear and neither is the suspension compliance set against a variable cone displacement.
Incorrect!
If the woofer did not move there would not be any pressure variation.
Pressure variation is what makes the mid-driver think that it is a passive radiator.
Bl(x) and compliance(x) need not be linear to be quantified.
The "disturbance" need not quantified. It can be measured with a in box pressure microphone. (impulse response)
The woofer moves causing delta pressure, delta pressure moves the passive radiator.
The MatLab script is the homework assignment.
In the days when hi-fi shops had dedicated listening rooms, they never even placed another set(s) of speakers in the same room since these passive (unconnected) speakers were excited by the main (playing) speakers and you heard them doing something to the sound. You had to book your listening session and they only had what you wanted to listen to in the demo room. What you are trying is far worse, the midrange will not only be excited and amplitude modulated by the back pressure but the phase lag between the two would smear the midrange and make your efforts moot. You don't need be an audiophile to hear this. Look up the specs of the midrange driver and what enclosure size is suggested and just do this. The enclosure need not be made of wood, you may even find a plastic drinking cup of the right volume and seal the midrange back in your box with hot melt glue.
Thanks for the explanation.
I should emphasize that the analysis in the PDF is only valid if the drivers are connected directly in parallel and directly to the voltage source. If the drivers are filtered separately, which is usually the case with a woofer and midtone, the situation is quite different.
What if the other speakers were shorted ?
I have also sometimes heard that, on the contrary, as many speakers as possible are placed in the demo room to act as bass traps.
I reread my post and you are right. The word ‘simply’ was missing. There of course is a relationship, but it is not that easy to describe. While linear within constraints, dynamic pressure at a given point in the enclosure is also dependent of standing wave patterns inside the enclosure. And think e.g. of the influence of a vent (if present).
To alleviate the problem that the other amps don't interfere you also have to short the incoming mains
Iirc that indeed can be done, preferably with shorted terminals. A good switching board does so. But even a not shorted loudspeaker actually damps pretty good, better than the equivalent air volume.
What you are suggesting then to be able to recreate the sound in the demo room you buy all the speakers and try to set them up in the same way that was done in the demo room? Unfortunately I have a limited budget,
Best not to use switching boards since the contact resistance can make a big difference. Besides can you prove your damping theory, I am sure there are folk here that can purchase several B&W 800s for bass traps. What size wire do you suggest for shorting speaker, should it be audiophile grade, silver coated or any other recommendation. Does the water in the pool rises when you get into the pool?
Are U angry with me? 😉
The ultimate problem with comparing speakers the way you suggest is that the human perceptual system isn't able to compare that way. After give or take half a minute one's memory on how a speaker sounded begins to fade. So there you are, rolling speakers in and out and losing reference in the process.
The ultimate problem with comparing speakers the way you suggest is that the human perceptual system isn't able to compare that way. After give or take half a minute one's memory on how a speaker sounded begins to fade. So there you are, rolling speakers in and out and losing reference in the process.