Easy, inexpensive cabinet for 12 inch subwoofer

[RickS]

Intended some outdoor measurements, but is too hot this week...

Listened to some of Amir's music and have been very pleased so far. Have not tried his bass torture tracks as yet. May be best to do with a subsonic filter on. My music is mainly on FLAC from CDs. His was streamed via Amazon Echo link streamer and Apple Music. May have to use my WiiM as some tracks are not being found despite being available on Apple Music. My old Macbook might do the trick too.

 

[RickS]

Weather does not stop some nearfield measurements though...

Green trace is woofer and yellow the port. These further confirms the sims. Notably a cabinet resonance just around 440 Hz that may need some attention. You will see this show up readily in the Bassbox group delay graph posted earlier. Also, a 2nd harmonic around 900 Hz.

 

[pablolie]

I have heard -several times- of DIY people that built sub cabinet enclosures out of concrete and swore by those.

 

[Andysu]

Up in the right corner. My subwoofer made of cardboard casting tubes. Dual 12 inch JBL bass drivers in saucer configuration, down firing.
View attachment 469154

Fascinating is that I did not experience resonances from the tubes themselves. However, I had to brace the plates on the top and bottom with side beams, to reduce vibratones. I was able to play loud as hell with that subwoofer. Unfortunately, I then destroyed the drivers by gluing the drivers together , glue that then also flowed out and destroyed them...but before that it was a high SPL fun seald subwoofer.

It was a cheap fun DIY subwoofer project.

Edit:
Two of these JBL bass drivers were in my tube subwoofer. Bought them cheap from a teenager. Actually for car bass but in a sealed box they worked well for home hifi.
View attachment 469155View attachment 469156

one of those yamaha active servo subs

 

[DanielT]

Weather does not stop some nearfield measurements though...

View attachment 469906

Green trace is woofer and yellow the port. These further confirms the sims. Notably a cabinet resonance just around 440 Hz that may need some attention. You will see this show up readily in the Bassbox group delay graph posted earlier. Also, a 2nd harmonic around 900 Hz.

Notably a cabinet resonance just around 440 Hz that may need some attention.

Okay, but why? If you have a, lets say a 24 dB LP filter with a cut off frequency at 100 Hz, then at 440 Hz it is well below the audible range in relation to the speakers. Then that problem is already solved, so to speak.

I have heard -several times- of DIY people that built sub cabinet enclosures out of concrete and swore by those.

Seems unnecessary for subwoofers. Unnecessarily heavy. As far as I understand it, plywood is great for subwoofers. Plywood has the right density and is relatively light.

Concrete for speakers. Maybe so. Probably overkill. In any case, here you can read about a test carried out on a Rauna concrete speakers:

'Rauna Freja Vintage 2-Way Loudspeaker Measurements'

Dec 3, 2023

Today I present measurements on a pair of Rauna Freja, aka affectionately as 'Swedish Tombstones'. They are a small 2-way in a concrete cabinet. I believe that Bo Hansson was involved with the design. I would appreciate any information members have regarding this nice little speaker.

These were made in the '80s, they are 100% original. Out of a discussion on another thread about the imagined virtues of avoiding measurements, I used the Rauna as an example of a speaker with weak bass but that still has a strong interaction with room modes and boundaries. Here I present...

• MAB
• Replies: 23
• Forum: Speaker Reviews, Measurements and Discussion

• 

one of those yamaha active servo subs

That's right, a Yamaha YST- SW90. Old but it was good. You can usually buy one of those for, well, barely any money at all.
But a thirty-five year old subwoofer. Who knows, it could give up any day. Humming amplifier in it and so on and so forth. That's what you should also consider when buying a used one.

 

[thewas]

That's right, a Yamaha YST- SW90.

The YST-150 and its successor 160 were measured from @puffreis as some of the lowest in distortion and can be also gotten cheap, I also bought and use some of them.

 

[RickS]

Notably a cabinet resonance just around 440 Hz that may need some attention.

Okay, but why? If you have a, lets say a 24 dB LP filter with a cut off frequency at 100 Hz, then at 440 Hz it is well below the audible range in relation to the speakers. Then that problem is already solved, so to speak.

Good point, except was considering using the same woofer as a bass module. My current use as a subwoofer makes it simpler to test the low end of the design and evaluate sound quality.

Seems unnecessary for subwoofers. Unnecessarily heavy. As far as I understand it, plywood is great for subwoofers. Plywood has the right density and is relatively light.

Fully agree. Part of the advantage of DIY is doing something that may not be commercially viable but the other side is a tendency to over-engineer too. Due to size and weight, this one is enough for my old back to wrestle around and have not added braces. Unless you make it thicker, concrete can crack and, if it is thicker, weight becomes an issue.

 

[DanielT]

Aha bass boxes, playing higher up in frequency. Then I understand. That's another matter.

Regarding subwoofers as such, which play up to say around max 100 Hz, which have steep cut off LP filters. Are resonances then a problem? Aren't they pushed up in frequency and become inaudible, masked by the sound of the speakers, that is?
If that is the case, why brace subwoofers boxes? Unnecessary work that has no practical significance, that is.

Filling subwoofers with damping, stuffing material then seems counterproductive because it can reduce efficiency.

For subwoofers, that is, for speakers, resonances need to be dampened in a different way. Also applies to bass boxes that play higher up in frequency, as you mentioned.

 

[RickS]

Realized my other RSS315HF was being used in an active subwoofer. So have now sliced another section of tube for a passive sealed subwoofer. This left another 20 inch piece to use to create a matched one later. Will cut some end caps tomorrow.

 

[dualazmak]

one of those yamaha active servo subs

The YST-150 and its successor 160 were measured from @puffreis as some of the lowest in distortion and can be also gotten cheap, I also bought and use some of them.

Sorry to be out of the scope of OP, but as for YAMAHA YST active servo technology...

I still use large and heavy L&R YAMAHA YST-SW1000 (W580xH440xD440 mm, 48.0 kg, 16 Hz - 160 Hz, spec etc. ref. here) !
You can find the latest system setup of my multichannel audio rig in my posts here #931 and here #1,009 on my project thread.
And,,,,
- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495

As for the audio reference/sampler music playlist and music tracks, my threads and posts under the below spoiler cover would be of your interest, I assume;

Spoiler

- An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition

- Music for Testing Treble (High Frequency) Sound

- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

- A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #63(remote thread)

 

[RickS]

Sorry to be out of the scope of OP, but as for YAMAHA YST active servo technology...

I still use large and heavy L&R YAMAHA YST-SW1000 (W580xH440xD440 mm, 48.0 kg, 16 Hz - 160 Hz, spec etc. ref. here) !
You can find the latest system setup of my multichannel audio rig in my posts here #931 and here #1,009 on my project thread.
And,,,,
- Measurement of transient characteristics of Yamaha 30 cm woofer JA-3058 in sealed cabinet and Yamaha active sub-woofer YST-SW1000: #495

As for the audio reference/sampler music playlist and music tracks, my threads and posts under the below spoiler cover would be of your interest, I assume;

Spoiler

- An Attempt Sharing Reference Quality Music Playlist: at least a portion and/or whole track being analyzed by 3D color spectrum of Adobe Audition

- Music for Testing Treble (High Frequency) Sound

- Reproduction and listening/hearing/feeling sensations to 16 Hz (organ) sound with my DSP-based multichannel multi-SP-driver multi-amplifier fully active stereo audio system having big-heavy active L&R sub-woofers: #782

- A nice smooth-jazz album for bass (low Fq) and higher Fq tonality check and tuning: #63(remote thread)

While I like the premise of motion feedback, not sure the benefit is there from a ROI perspective. Also do not like limited choices in drivers and amplifiers for my needs. If I get a chance to hear, may change my mind, but is where I am at today.

 

[RickS]

Well the sealed one should have been first as it was much simpler. Here are the pieces. The back baffle is very simple and is a 18x18 piece of 3/4 inch MDF with a 16.25 inch o.d. groove. The groove is 1/4 inch wide by 3/8 inch deep…



The next part is the front baffle and has an identical groove, but adds a 11 3/16 inch cutout for the driver…



Add a 8 inch section of the 16 inch cardboard tube and this is the dry fit…



Shown with planned binding post location. I plan to test this subwoofer downfiring so need a location that works horizontally or vertically. The best location might be on the tube but it is not as strong or easy to patch if I relocate.

 

[RickS]

The sealed one is up and running and matches the sim well. The f3 is about 50 Hz. Have not done any measurements other than impedance. Am pleased to find that it still sounds pretty good. Does not have the low end grunt that the vented box does but does pretty well for such a compact enclosure.

As I mentioned, for comparison plan to eq to better match the vented low end. When I do so, I notice the group delay becomes very comparable above 30 Hz. So, if sealed sounds better, seems I only the get if I compromise the deeper bass?

 

[DanielT]

The sealed one is up and running and matches the sim well. The f3 is about 50 Hz. Have not done any measurements other than impedance. Am pleased to find that it still sounds pretty good. Does not have the low end grunt that the vented box does but does pretty well for such a compact enclosure.

This is a placeholder for the sealed Bassbox sim.

As I mentioned, for comparison plan to eq to better match the vented low end. When I do so, I notice the group delay becomes very comparable above 30 Hz. So, if sealed sounds better, seems I only the get if I compromise the deeper bass?

Regarding the low end grunt.
If you have a fair amount of power reserves/headroom in your subwoofer amplifier and if the sub speaker driver has a fair amount of power, you can use Linkwitz Transform/EQ and extend the lowest frequency. That's because you have a sealed subwoofer that makes it possible.
(a ported sub that rolls off quickly, this cannot be done, you cannot conjure/fix what is not there to be brought out)

As long as you don't play at nightclub levels and stress the amp and speaker driver by pushing down the lower frequency, it should work well. But you have to find out for yourself if Linkwitz Transform/ low EQ boost (or lower the higher bass frequencies) suits you. If you think you need it?

 

[RickS]

Regarding the low end grunt.
If you have a fair amount of power reserves/headroom in your subwoofer amplifier and if the sub speaker driver has a fair amount of power, you can use Linkwitz Transform/EQ and extend the lowest frequency. That's because you have a sealed subwoofer that makes it possible.
(a ported sub that rolls off quickly, this cannot be done, you cannot conjure/fix what is not there to be brought out)

Is what I am doing btw. The subwoofer amp is a bridged NC502MP so power is there. Had considered the Linkwitz transform but for testing just wanted to give the sealed version comparable low end. This only requires about 4 dB peak filter to do. Will be trying later.

As long as you don't play at nightclub levels and stress the amp and speaker driver by pushing down the lower frequency, it should work well. But you have to find out for yourself if Linkwitz Transform/ low EQ boost (or lower the higher bass frequencies) suits you. If you think you need it?

I like having and is useful for home theater. Whether it is absolutely necessary is part of my experiment. If added power handling is needed, can add more subwoofers. My wife would like smaller subwoofers.

 

[RickS]

My initial listening comparison of the sealed subwoofer revealed little difference between the bass with the eq boost vs without for my music. Comparing sealed vs vented will take some more setup and will wait until next week.

 

[Wizard509]

Well the sealed one should have been first as it was much simpler. Here are the pieces. The back baffle is very simple and is a 18x18 piece of 3/4 inch MDF with a 16.25 inch o.d. groove. The groove is 1/4 inch wide by 3/8 inch deep…

View attachment 472763

The next part is the front baffle and has an identical groove, but adds a 11 3/16 inch cutout for the driver…

View attachment 472765

What fixture do you use for routing grooves and cutouts? Are you using a full-size router? Thanks!

 

[RickS]

What fixture do you use for routing grooves and cutouts? Are you using a full-size router? Thanks!

Am using a jasper jig that had to be slightly altered to accommodate a Grizzly cordless compact router. No cord is nice as a corded one can drag (notably after a few passes).

Also using the dust collection attachment as it makes a huge improvement in containing the MDF dust (highly recommended!).

 

[Wizard509]

Am using a jasper jig that had to be slightly altered to accommodate a Grizzly cordless compact router. No cord is nice as a corded one can drag notably after a few passes.

Also using the dust collection attachment as it makes a huge improvement in containing the MDF dust (highly recommended!).

Thanks. I'll look at the Jasper jig. I have quite a few cordless Dewalt tools and a cordless router has been on my "wish list" for a while. I'll have to see if a dust collection system is available for it. If not, then I will look at other options.

 

[RickS]

Have been doing some more listening. In one setup, I moved the vented subwoofer into the corner and disconnected the sealed one. I am testing subwoofers with my CBT24s and noticed how the vocals would sound like they came from the subwoofer when centered in between the stereo pair. Noticed this still was the case with the sealed subwoofer disconnected. Confirmed my own bias/biases by placing the sealed subwoofer higher. The vocals moved with the subwoofer. Will spend a bit more time trying other positions. However…

My main goal is to work on bass quality so next will measure distortion from each subwoofer. Am also considering a dual opposing build for comparison. I have done some initial design and have enough tube to spare. If really want to AB compare them, need to invest in a couple more drivers.