Most important parameters for deep bass in a small box?

[Mr Sinister]

As the topic states, I'm curious what woofer parameters are most important for getting deep bass in a small box. Low Fs and high Xmax come to mind. But what else? Low Vas?

[Chris Roemer]

F3 is determined by Fs and Qts(higher is better). Vb is determined by Vas and Qts(lower is better).
At a Qts right around 0.40 you can usually get F3 to = Fs, and Vb to = Vas.
As Qts rises, F3 goes down and Vb goes up. Going below 0.40 Qts, F3 rises and Vb goes down.

Look at TangBands W5-1138 and W6-1139 for inspiration.

Port length becomes problematical.

[Ugg10]

Remember that for any speaker you have to trade Low frequency output with box size with sensitivity, if you want low frequency and small box you will have low sensitivity and therefore need lots of power and probably a separate amp.

[aarond]

$$$ is the most important parameter

Lots of money for a big motor on the driver, lots of money for a big amp to effectively drive an inefficient setup, lots of money to get a capable passive radiator because the port lengths in a small box aren't practical.

[DeZZar]

...deep bass in a small box.

Chris has provided all the facts. It's a game of trade off's essentially. But 'deep' and 'small' are fairly subjective - what's small for you and what's deep? And what's the application - that's probably the biggest factor here. There is also an SPL limitation/compromise. Small woofer, small enclose, playing deep bass = low output. High output = larger woofer, larger enclosure, higher x-max and thermal power handling....

For full spectrum music reproduction nothing, (IMO), NOTHING can hold a candle to a large, high sensitivity woofer in a large (make that 'appropriately' sized) enclosure, except two of them.

Movies, different story - in that application you can easily put up with some forced/active bass from a subwoofer, go small box, high excursion woofer, eq it to satisfaction.

[devnull]

Hofmann's iron law, pick two out of three....

1. Low bass reproduction
2. Small enclosure size 3. High sensitivity

Because you want the first two you need to look for a low efficiency driver and throw a boatload of power at it. So lots of Xmax and amp power.....

[Mr Sinister]

Thank you everyone for the replies! That gives me something to think about. I'm just brainstorming ideas at this point, no specific project in mind yet!

[fpitas]

$$$ is the most important parameter

Lots of money for a big motor on the driver, lots of money for a big amp to effectively drive an inefficient setup, lots of money to get a capable passive radiator because the port lengths in a small box aren't practical.

Of course you *can* run the port outside the box, like a crazy exhaust header.

[DaveFred]

Money.

[fpitas]

Be practical about your expectations. Bragging rights aside, music doesn't usually have much below 40Hz, and in the normal listening room you'll get cabin gain, which will tend to boost the lowest frequencies.

[wogg]

Be practical about your expectations. Bragging rights aside, music doesn't usually have much below 40Hz, and in the normal listening room you'll get cabin gain, which will tend to boost the lowest frequencies.

...usually...

When something in my playlists shows up with 30 something content that I know should be there, but isn't reproduced... that makes me very sad :(. Granted, that's a small percentage of my listening, but that small percentage is important and really cool when reproduced. I shoot for mid to low 30's myself for music, and low 20's for movies.

[fpitas]

...usually...

When something in my playlists shows up with 30 something content that I know should be there, but isn't reproduced... that makes me very sad :(. Granted, that's a small percentage of my listening, but that small percentage is important and really cool when reproduced. I shoot for mid to low 30's myself for music, and low 20's for movies.

Sure, I agree. But I bet you're not expecting miracles from a tiny subwoofer, either.

[wogg]

Sure, I agree. But I bet you're not expecting miracles from a tiny subwoofer, either.

Very true, lower SPL as required by physics. That was sort of unrelated to the topic.

[Brian Steele]

Look into passively-assisted sealed systems. Other than using PRs, it just might be the best way to get a lower F3 in a small box.

[Steve Lee]

https://www.jstor.org/stable/44721690