I have an Adire DPL12 in a 2.4 cubic foot sealed box and just recently stuffed it completely. The results were not good. It lost SPL and slam factor. So, I opened it back up and removed some stuffing and now it is about 1/2 full like it always was before. The SPL and slam came back. When I was testing it, I had no stuffing in it, and it had even more slam. I might go back to that if I feel like opening it back up. So, in my experience, stuffing was bad.
Stuffing is bad in a sub, and unnecessary. The wavelengths reproduced in a sub are unaffected by stuffing and do not require attenuation within the box as they are too long compared to the box dimensions for standing waves to develop. The idea of using stuffing to increase apparant box size is a carryover from the pre-T/S days and really does not apply to subs. Stuffing/lining is a must for frequencies from about 300 Hz and up.
So what is it about stuffing that takes away slam from subs? I can't see what theory would support the subjective comment!
If it's a sealed subwoofer, then it lowers the Q, which should be a good thing! From a fidelity point of view. Perhaps this perceived loss of slam is actually greater accuracy. As I understand, a lower Q will often mean better transient response, by making the box appear bigger.
I can't see why stuffing a sub should be considered a "pre TS parameters thing."
I have heard that stuffing is not a good idea for a vented box. However, if the vent is not blocked and it is partially stuffed, I'm not sure what effect it might have.
I can see the point however, that small changes in box volume aren't that significant for a sealed sub - the response changes very little. It is more a question of transient response I believe.
If it's a sealed subwoofer, then it lowers the Q, which should be a good thing! From a fidelity point of view. Perhaps this perceived loss of slam is actually greater accuracy. As I understand, a lower Q will often mean better transient response, by making the box appear bigger.
I can't see why stuffing a sub should be considered a "pre TS parameters thing."
I have heard that stuffing is not a good idea for a vented box. However, if the vent is not blocked and it is partially stuffed, I'm not sure what effect it might have.
I can see the point however, that small changes in box volume aren't that significant for a sealed sub - the response changes very little. It is more a question of transient response I believe.
My measured results show that subs are more sensitive and have a smoother response curve without stuffing. That would qualify as 'better' according to most definitions.
As I noted earlier using stuffing/lining in woofers dates to pre-T/S. Back then most hi-fi cabinets were quite large, and the internal dimensions were long enough to allow low frequency standing waves to develop; stuffing and lining helped suppress them. The apparant increase of box volume that could be achieved was also beneficial when box sizes of 8 cubic feet and more were not uncommon.
Also, prior to about 1980 the great majority of speakers used woofers that ran 1kHz or better, and they needed lining/stuffing to suppress internal midbass and midrange reflections, irrespective of cabinet size. That still applies today with speakers that operate to above 300 Hz or so. However, for frequencies below that, with today's smaller cabinet dimensions (less than 1/4 wavelength within the passband), lining and stuffing is by and large detrimental to performance. Most manufactuers of subs continue to use it out of habit more than anything else.
These facts were not lost on speaker designers of yesteryear, especially with regards to reflex designs. It was well known that bass response suffered with stuffing and lining but it was usually employed anyway as the degradation of midbass and midrange performance resulting from a lack of damping was far more injurious to the overall sound than the loss of bass response, especially with the wide range woofers used almost exclusively prior to the invention of the subwoofer concept in the late 1970s.
As I noted earlier using stuffing/lining in woofers dates to pre-T/S. Back then most hi-fi cabinets were quite large, and the internal dimensions were long enough to allow low frequency standing waves to develop; stuffing and lining helped suppress them. The apparant increase of box volume that could be achieved was also beneficial when box sizes of 8 cubic feet and more were not uncommon.
Also, prior to about 1980 the great majority of speakers used woofers that ran 1kHz or better, and they needed lining/stuffing to suppress internal midbass and midrange reflections, irrespective of cabinet size. That still applies today with speakers that operate to above 300 Hz or so. However, for frequencies below that, with today's smaller cabinet dimensions (less than 1/4 wavelength within the passband), lining and stuffing is by and large detrimental to performance. Most manufactuers of subs continue to use it out of habit more than anything else.
These facts were not lost on speaker designers of yesteryear, especially with regards to reflex designs. It was well known that bass response suffered with stuffing and lining but it was usually employed anyway as the degradation of midbass and midrange performance resulting from a lack of damping was far more injurious to the overall sound than the loss of bass response, especially with the wide range woofers used almost exclusively prior to the invention of the subwoofer concept in the late 1970s.
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