Super Compact Subwoofer Design

[grahamgraham]

Hi all,

Total newbie here so I hope someone can help me with some questions please!

I've done extensive couch-based research and searched the forums here but I can't find definitive answers...

I want to make a super compact subwoofer for my kitchen (girlfriend won't tolerate large cabs) and I have in mind the Tang Band 5 1/4" subwoofer driver which I would like to put in a very small cab which I have attached an image of.

My questions are:

1. The manufacturer specifies "Vented Volume0.26 ft.³" - does this have to include the port volume area as well?

2. How small could I make a vented sub with this driver? I want to make it very thin and long to fit under a table.

3. In the (very) rough design I sketched I have a t-line like vent. Will this benefit the sub in the most compact cabinet I can use?

Like I said, very much a newbie to this craft so would really appreciate some help, thank you!!!

 

[MartyMG]

http://techtalk.parts-express.com/showthread.php?238765-Voxel-a-mini-sub&p=1929280#post1929280

This may be helpful to your project Graham.

 

[richie00boy]

The volume occupied by the port is in addition to the recommended "box volume". Your proposed design is a good way to make a compact sub.

 

[TBTL]

The box you sketched will behave as ported, not as a transmission line. You might want to reduce the number of bends, as each bend induces losses and port noise. A straight port works best. If you have to make bends, make the bending radius as large as possible.

 

[AndrewT]

You will find that a tube port wastes less space than a slot port.
Besides wasting space, a slot port is also much heavier.

You cannot make a slot port from 3mm thick plastic/plywood/mdf, you can make a tube port from 3mm plastic.

 

[grahamgraham]

Voxel - a mini-sub+ - Techtalk Speaker Building, Audio, Video Discussion Forum

This may be helpful to your project Graham.

Thank you, very helpful!

He has it tuned to 35hz with a round port, how would I adapt his design to a slotted port?

I can't use the same volume area as the round port as it would make the slot too thin and introduce noise...

 

[grahamgraham]

The volume occupied by the port is in addition to the recommended "box volume". Your proposed design is a good way to make a compact sub.

Great, I'm glad I'm on the right trail.

This sub requires tuning to 35hz, how long and wide would I have to make my slotted port?

Above an article suggested a length of 9" with a 1.5" round port. Can I use the same length but make the port 1" wide (utilising one full end height of the cabinet)?

I understand I can't have too narrow a port or it will whistle(!).

 

[grahamgraham]

Thank you for your replies!

How would I pick a suitable width and length for tuning to 35hz. I have read a 9" circular port would do this. Would this type of vent need to be 9" long?

My presumption is that a 0.75-1" width port that is about 6" high with a length of 9" should be suitable? Would this work?

Thank you all again!

 

[tb46]

Hi grahamgraham,

Post #1: "...help me with some questions please!...I can't find definitive answers..."

Here are some links:

1. Brian Steele's page: The Subwoofer DIY Page then:

2. subwoofer builder on ports: Port Flares and:

3. Elliott Sound: DIY Audio Articles

That should get you started.

I recommend learning Hornresp to simulate your enclosure.

I'll attach a simulation using the data you provided: bass-reflex enclosure for a Tang Band W5-1138SMF: net volume of rear chamber Vrc=7.36 liter (.26ft^3), and 1.5"Dia.(area: Ap=11.4cm^2) by 9" long (length Lpt=22.86cm) port (duct/vent).

The ***.txt file can be exported into Hornresp. Hornresp is available as a free download here: Hornresp

There is a lot of support here @ diyaudio, and elsewhere for Hornresp, and it comes w/ a good help file. Also, to get you started:

Hornresp for Dum... hmm... Everyone - Home Theater Forum and Systems - HomeTheaterShack.com

I'll attach some data on ports posted by bjorno. You can search the diyaudio subwoofer forum advanced search for, e.g.: Keyword: ports User Name: bjorno, or ports/GM, and you'll find all kinds of entries.

I would recommend a slightly larger enclosure, and a bigger cross-section port (maybe 2"Dia.?). But, you can fiddle around in the Wizard in Hornresp, and make up your own mind.

Good luck w/ your project.

Regards,

 

[tb46]

Post #9

Hi again,

I messed up in Post #9, and posted the simulation/SPL for a dual driver box using the W5-1138SMF. Load simulation into Hornresp, under Tools - Driver Arrangement choose 'Normal Nd' click OK, and the Input screen field that now says 'Nd 2S' should say 'Nd 1'. Then you can play around w/ the volume, etc...

Regards,

 

[Djim]

I want to make a super compact subwoofer

Hi grahamgraham,

A passive radiator instead of a port can reduce the volume even more.

Regards,
Djim

 

[wolf_teeth]

Yep:



Have fun contorting the box to be shallow and long....Keeping volume intact,
Wolf

 

[tb46]

Hi Y'all,

H Djim, yes, a passive radiator would be a better solution for this driver. I like a single Dayton 8" as shown by wolf_teeth in Post #12, or maybe two 6.5" Dayton SD175-PR. Hornresp now has passive radiator functionality, see 'Help' file.

Regards,

 

[grahamgraham]

Wow!!! So much info, thank you so much I have a lot to learn!

I am about to post a second revision of my design and would love your opinion!

Thanks!

G.

Hi grahamgraham,

Post #1: "...help me with some questions please!...I can't find definitive answers..."

Here are some links:

1. Brian Steele's page: The Subwoofer DIY Page then:

2. subwoofer builder on ports: Port Flares and:

3. Elliott Sound: DIY Audio Articles

That should get you started.

I recommend learning Hornresp to simulate your enclosure.

I'll attach a simulation using the data you provided: bass-reflex enclosure for a Tang Band W5-1138SMF: net volume of rear chamber Vrc=7.36 liter (.26ft^3), and 1.5"Dia.(area: Ap=11.4cm^2) by 9" long (length Lpt=22.86cm) port (duct/vent).

The ***.txt file can be exported into Hornresp. Hornresp is available as a free download here: Hornresp

There is a lot of support here @ diyaudio, and elsewhere for Hornresp, and it comes w/ a good help file. Also, to get you started:

Hornresp for Dum... hmm... Everyone - Home Theater Forum and Systems - HomeTheaterShack.com

I'll attach some data on ports posted by bjorno. You can search the diyaudio subwoofer forum advanced search for, e.g.: Keyword: ports User Name: bjorno, or ports/GM, and you'll find all kinds of entries.

I would recommend a slightly larger enclosure, and a bigger cross-section port (maybe 2"Dia.?). But, you can fiddle around in the Wizard in Hornresp, and make up your own mind.

Good luck w/ your project.

Regards,

 

[grahamgraham]

Thanks everyone for the input!

I have had a really good look at the Voxel Sub and taken onboard the suggestion that it needed a slioghtly larger cabinet and port.

So I have attached my new design (MK3 doodle and model) that has an 8 litre cabinet with around a .5l port which is 5" high by 8.5" long.

I am a little concerned the port is a bit too large, can anyone advise on this?

Thank you!!!

 

[grahamgraham]

Just to clarify, the port is 8.5" x 5" by 0.5" and is flared on the intake section and the output section.

 

[grahamgraham]

Yep:



Have fun contorting the box to be shallow and long....Keeping volume intact,
Wolf

I think I have contorted them to them to the best I can! See above photos! Thanks for the advice!!