Please correct me if I'm wrong but all things being equal, a smaller box will require more EQ to achieve similar low-end extension compared to using a larger enclosure.
More EQ means more power is needed. But in terms of actual excursion used, there is no difference between a small box + EQ and a large box without EQ - same amount of excursion needed to achieve similar extension?
So the only real downside to using a small box is the potential for reaching thermal compression? Is that all correct?
More EQ means more power is needed. But in terms of actual excursion used, there is no difference between a small box + EQ and a large box without EQ - same amount of excursion needed to achieve similar extension?
So the only real downside to using a small box is the potential for reaching thermal compression? Is that all correct?
Hi,
You have it pretty much right. You can reduce box volume for the
same excursion at the expense of needing more power. Most
commercial subwoofers fit into this category, they are EQ'd.
Given a driver, with a given excursion, how far you can take
this, smaller box and more power, is a thermal issue. But
more power means more money, so for a given driver
there is balance involved regarding power and box size.
rgds, sreten.
You have it pretty much right. You can reduce box volume for the
same excursion at the expense of needing more power. Most
commercial subwoofers fit into this category, they are EQ'd.
Given a driver, with a given excursion, how far you can take
this, smaller box and more power, is a thermal issue. But
more power means more money, so for a given driver
there is balance involved regarding power and box size.
rgds, sreten.
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For some reason I assumed that a small box needed more excursion to hit the desired F3 compared to a larger box. But it all evens out.. in some way. You just need more power.
Sorry, just to add : is it true that larger boxes don't require as much EQ to reach F3 as a smaller box?
Correct.
Think of it like this - a given cone area and excursion results in a certain SPL at any given frequency.
If the box is small, the cone is being held still (moreso than a larger cabinet), so you must put more power in to make the cone move the amount required to produce that SPL at that frequency.
Efficiency changes, but maximum SPL (so long as you're within thermal limits) does not.
If the above doesn't make sense, ignore it. I'm 90% sure you know what's going on anyway.
Chris
I saw this on the net where someone countered the big box less EQ argument (below) :
"The F3 of the system in the small box can be dropped as low as desired by increasing the mass of the cone, and then no eq is required to offset the effects of a higher F3. Designers have the option not adding the extra mass, but then F3 rises and they need more LF eq. The trade off is that system with the higher F3 has more efficiency at F3 and above. The point is that either situation can be obtained in a small box with different drivers.
A key point is that the difference in equalization required for comparable response is based on where F3 is, and is required to provide the same excursion versus frequency versus cone area. Equalization boost comes at the cost in amplifier power, but it doesn't reduce the ability of a given cone area and linear excursion to provide clean bass."
So I'm a little confused now. So then what is the point of using a bigger box? I assumed bigger box, less EQ, less power required and hence less chance for thermal compression but the above is confusing a bit. Not sure if the above is valid or not.
"The F3 of the system in the small box can be dropped as low as desired by increasing the mass of the cone, and then no eq is required to offset the effects of a higher F3. Designers have the option not adding the extra mass, but then F3 rises and they need more LF eq. The trade off is that system with the higher F3 has more efficiency at F3 and above. The point is that either situation can be obtained in a small box with different drivers.
A key point is that the difference in equalization required for comparable response is based on where F3 is, and is required to provide the same excursion versus frequency versus cone area. Equalization boost comes at the cost in amplifier power, but it doesn't reduce the ability of a given cone area and linear excursion to provide clean bass."
So I'm a little confused now. So then what is the point of using a bigger box? I assumed bigger box, less EQ, less power required and hence less chance for thermal compression but the above is confusing a bit. Not sure if the above is valid or not.
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Yes that is exactly what it means.
It is all very well adding mass to lower Fs, but as the person pointed out it also reduces efficiency. So you still need to add more power to get the same SPL as before you added the mass.
It always will.
What matters is how much compression - loosing 0.1dB to thermal losses isn't a problem - nobody's going to notice.
Its when it gets above 2 or 3dB that the problems start - when you lose 3dB to power compression, you may as well put half the power in (2x power = +3dB) and reduce your losses.
Chris
Hi,
What is missing from the above is if you vary the cone mass to keep
Fbox constant you need more power for the higher mass, as the
efficiency drops, and a bigger magnet too, to maintain Qbox.
The point regarding box size often boils down to using a bigger
amplifier (than needed say for a Qbox of 0.7) and a smaller
box with a linkwitz transform, simply for size convenience.
rgds, sreten.
What is missing from the above is if you vary the cone mass to keep
Fbox constant you need more power for the higher mass, as the
efficiency drops, and a bigger magnet too, to maintain Qbox.
The point regarding box size often boils down to using a bigger
amplifier (than needed say for a Qbox of 0.7) and a smaller
box with a linkwitz transform, simply for size convenience.
rgds, sreten.
Hi,
Of course that is possible if you choose the right driver.
Depends what you mean by flat though, it will roll-off
at a certain bass frequency depending on parameters.
rgds, sreten.
Of course that is possible if you choose the right driver.
Depends what you mean by flat though, it will roll-off
at a certain bass frequency depending on parameters.
rgds, sreten.
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Well if you use a large box with a given driver, you put that same driver in a small box, it's possible that driver (whatever you use) may have flat response in the small cabinet but not in the large cabinet. So then you would have to use EQ to correct for it.
Is that possible?
Is that possible?
I'm busy arguing with a guy (big time expert apparently) who tells me that I must have flunked thermodynamics as he tells me that more heat does not necessarily mean higher temperatures re more amp power means higher chance of reaching thermal compression.
His name is Arny ... had a few debates with John Wilkinson over at Stereophile so the guy apparently has some credibility. I'm obviously not anywhere in his league, but I find his comments strange.
His name is Arny ... had a few debates with John Wilkinson over at Stereophile so the guy apparently has some credibility. I'm obviously not anywhere in his league, but I find his comments strange.
Hi,
Generally there would be very little point putting a driver flat in a small
cabinet into a larger cabinet. However it depends on the sealed box Q
that is your target. Lower Q's need bigger boxes as do vented boxes.
rgds, sreten.
Generally there would be very little point putting a driver flat in a small
cabinet into a larger cabinet. However it depends on the sealed box Q
that is your target. Lower Q's need bigger boxes as do vented boxes.
rgds, sreten.
So you can't hit a lower target Q in a smaller box unless you use a specific driver designed for it?
Hi,
Yes that is true, its all compromises, the driver
design decides the compromises available to you.
rgds, sreten.
Yes that is true, its all compromises, the driver
design decides the compromises available to you.
rgds, sreten.
Well more power is more heat, but without seeing any of the context of what he is saying it's not possible to comment.
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