Have box size, need advise

NoDad

Member
2017-10-06 1:54 am
Almost first time DIY’er here. Built a speaker kit many, many moons ago (back it the 70’s). Looking at building a pair of sub-woofers. Have done a lot of research, but it seems the more I read the more confused I get.


My bookshelf speaker are wonderful, but are lacking a little in the bass, -3dB at 50Hz. I would like to extend this downwards a little. Don’t need wall shaking bass, but there are cases where I do miss something going a little further down.



What I’m considering is to build two sub-woofers as stands for the bookshelf speakers. The bottom of speakers are about 11" x 11" and need to be approx. 26” off the floor. May be able to add an inch or so to these measurements, depending on how the box/stand is designed.



Even though the stereo is also doing double-duty providing the sound for Netflix and movies the most (only) important reason for adding the subs is the music.


Downloaded WinISD and have been playing with it and Dayton Audio 8" woofers, but I'm not quite sure what I'm doing.



Any ideas how to go about this? Should I go sealed? Or ported? Is 8" enough or is it possible to squeeze in a 10" woofer?
 

NoDad

Member
2017-10-06 1:54 am
Hi, if you go sealed you get a woofer for 34 Liters. If you prefer BR (for home cinema like) you look for 28/30 Liters NET as a starting point. Those are taking you on different directions. Sealed vs. BR.


BR = ported?



The most important role for the subs is to play music. Whatever extra they give to movie watching is good, but not as important.


If I understand correctly, sealed will start the downward slope (frequency wise) earlier, but not as steep. Ported will be "straight" further down, but drop off faster when it starts to drop. Is this correct?



With my preference for music, is there a preference for one type over the other?
 
Subs

Just thought about something. When you say two woofers, do you mean two woofer drivers per enclosure or that there will be two enclosures, each with one driver?

NoDad:

You have a good sized room, especially with the additional volume of the hallway. Some suggestions for you to get started:

1. No one will be able to tell you what is going to appeal more to you. They have no way of knowing.

2. Sealed subs are easier to build, and less likely to result in a less than desirable outcome. Personally, I much prefer the sound of sealed subs, and am building a set now.

3. Stick to one driver per cabinet. If you desire to go with 2, such as your 8" idea, it will likely be cheaper to buy one better 10".

4. You will want to build it very sturdy, and you won't want it to dance around your room with your bookshelf speakers on top. From the description you gave of your listening habits, that doesn't seem likely anyway. If the other speakers are 11 x 11, you might consider making the sub just a bit bigger to give them a nice sturdy surface to sit on. And that could allow for a larger driver, which generally helps with subs.

5. There are great knock-down kits (pre-cut) from people like Parts Express and DIYSG.

6. Subs TEND to be built with larger drivers than you originally stated, just because IN GENERAL they end up impressing the audience more. I remember when I had 8", then 10, 12, 15, it never ends.........:)

7. You will want to think about material...some basic choices being MDF and plywood. I like Baltic Birch.

Have fun!
 

NoDad

Member
2017-10-06 1:54 am
Homebuilder - Great points.

Your points got me thinking. If I go 12" both width & depth on the cabinet then I can put some small "side wings" on the sides on top. Got the idea from Ellipticor-4 , but make mine much smaller. Maybe 1/4" to 1/2" inch tall.

I'm also considering designing some feet or base plate wider than the box itself. Just to get some additional stability.

Also, going 12" wide would allow a 10" driver. Bigger is always better, right :) Looking at the Dayton Audio RSS265HF-8 10" Reference HF Subwoofer 8 Ohm, Parts Express recommends 0.88 cuft sealed box. Which would work for me. Is this a good fit? Any other drivers I should look at?

I was planning to use Baltic birch as I really like the light wood look. When you say sturdy, would 1" thick be enough? Would I still need bracing?
 
Subwoofer

Homebuilder - Great points.

Your points got me thinking. If I go 12" both width & depth on the cabinet then I can put some small "side wings" on the sides on top. Got the idea from Ellipticor-4 , but make mine much smaller. Maybe 1/4" to 1/2" inch tall.

I'm also considering designing some feet or base plate wider than the box itself. Just to get some additional stability.

Also, going 12" wide would allow a 10" driver. Bigger is always better, right :) Looking at the Dayton Audio RSS265HF-8 10" Reference HF Subwoofer 8 Ohm, Parts Express recommends 0.88 cuft sealed box. Which would work for me. Is this a good fit? Any other drivers I should look at?

I was planning to use Baltic birch as I really like the light wood look. When you say sturdy, would 1" thick be enough? Would I still need bracing?

NoDad: I cannot comment on that particular driver, because I've never seen, or heard it. But, there are LOTS of really good, reasonably priced woofers available. Keep reading up on this site. You will see a lot of good ideas.

You don't need 1" plywood for a smaller sub, 3/4" would be fine. You will get more benefit from bracing than from the extra thickness of wood. But, double up on your baffle, and put a nice big round-over on the inside.

If you have some skill with woodworking, your idea of making the base or feet wider is a good one. You could also make the cabinet similar to a pyramid with the top cut off for your speaker to sit on.

My advice is to look at larger woofers. You are likely to do this once, so why not? That is a pretty good size room...a 12" or 15" would be great. Take a look at the DIYSG buyout sub for $150 each. They are incredible. I'm building a set now.

Make sure you use plenty of glue, brace the heck out of it, take your time. Have fun.
 

NoDad

Member
2017-10-06 1:54 am
Have fun.

That's my actual signature for my work email :) And, I try to live up to it.

Again thanks for your tips. Good news about the plywood. I'm sure 3/4" is easier to work with. I was planning to double-up the baffle & I'll remember to brace it. Any minimum size the holes have to be in a brace?

I'm not sure the wife want larger cabinets. She vetoed a pyramid cabinet earlier. I'm thinking 10" is about max I can go. Hoping it will be enough as I really don't need to go lower than 30-40 Hz.

Anyone have a suggestion for a good 10" woofer? Doing some calculation I can go up to about 38 liter (1.3 cuft) inside cabinet volume. Is it better to stay close to the recommendations I sometimes see for the woofer elements? Will increasing the cabinet volume be better?
 
10" subwoofer

That's my actual signature for my work email :) And, I try to live up to it.

Again thanks for your tips. Good news about the plywood. I'm sure 3/4" is easier to work with. I was planning to double-up the baffle & I'll remember to brace it. Any minimum size the holes have to be in a brace?

I'm not sure the wife want larger cabinets. She vetoed a pyramid cabinet earlier. I'm thinking 10" is about max I can go. Hoping it will be enough as I really don't need to go lower than 30-40 Hz.

Anyone have a suggestion for a good 10" woofer? Doing some calculation I can go up to about 38 liter (1.3 cuft) inside cabinet volume. Is it better to stay close to the recommendations I sometimes see for the woofer elements? Will increasing the cabinet volume be better?

NoDad: Take a look at Peerless woofers. A lot of people use them and are very happy with their performance. SBA are really good too. What is your budget?
 
Subwoofer

I haven't really set a budget yet, as I haven't researched all I need to complete the project. I guess I'd like to come in at less than $1000. Am I correct in assuming the woofers themselves will be the biggest cost?

NoDad:

$1000 is a pretty reasonable budget to work with for a pair of small subs. It depends a lot on what you need to complete the job. If you are thinking of using plate amps to power these, that is going to chew up a substantial part of your budget. Do you have existing amp channels you can use? Do you have the requisite outputs on your equipment to provide a signal for the subs? Etc.

It sounds to me like you are going to build something about 1-2 cubic feet in volume. A couple sheets of plywood is going to take care of that. Or, you can pick up a knock down cabinet from DIYSG for a very reasonable cost. You have plenty of time to do this, so you can look for bargains. Don't be in a hurry.

I'll jump on a soapbox here for a minute or two: in the last couple of decades, there have been some incredible advances in material technology for drivers, amplifiers, digital processors, etc. It seems most people (on this forum at least) are headed into DSP, very high powered amps, etc. Personally I don't get excited watching special effects on movies, because to me, once you've seen a few, you have seen them all. I'll never be in the camp of 2000-4000 watt amps so you can "feel" yet another special effect. I just like good music. To each his own.

If you listen at normal levels as you indicated early on, there are lots of really good amps for reasonable prices that will power a quality woofer to satisfactory levels. I'd much rather own separate amps, because they can be sold or traded up if you like, rather than something like a built in plate amp. Perhaps you are one of the people who wants to build your own amp??? I have no idea. I don't have the time or skills to do that, and don't want to learn how.

A couple things you could consider:

1. If you really like your bookshelf speakers, you could extend the cabinets to become a floor stander, and house additional woofers, or a sub. That would take more effort than just building a sub, if you want to get it right.

2. You could build some simple stands, and then put subs in a different location in your room, where they could possibly sound better. If this is a possibility for you, there are some really fun ideas to look at, like making subs out of something like a Sonotube form, a piece of heavy wall sewer pipe, etc. For the size you are talking about, you could get scraps from any construction site for free. (Ask first) That would really extend your budget a lot, because your cabinet cost could be as low as $20 each. I don't know, maybe free.

3. Look at "The cult of the Infinitely Baffled" website for some great ideas on an infinite baffle sub to consider if that could be an idea for your room.

4. Hang out around places that recycle vintage stuff, and pick up some cool old cabinets and re-purpose them. I recently picked up two perfect condition 5cf 1" thick plywood cabinets for $80 total at a Goodwill store. I'm making them into subs now. They were within 1/2" of the size I wanted to build anyway.

5. Sell your bookshelf speakers and build a modern kit that does everything you want, and takes advantage of modern materials., etc. For your budget, you can have an awesome set-up.

Lots of good choices!
 

NoDad

Member
2017-10-06 1:54 am
homebuilder:
I really like my speakers and will probably never get rid of them (famous last words, right!?!?). What started me on the DIY path was that I want to use the subwoofers as stands and couldn't find any commercial sub with the right measurements. Using them as stands limits the measurements to max. 12x12x26" (30x30x66 cm), which equals a net volume of around 37 liters.


I have been playing with WinISD and come up with a couple of ideas. In the picture below, the green graph is an 8" ported design. The blue is a 10" sealed box. Since my goal is to extend the bass to around 30 Hz, which of these is a better choice? For the ported design it shows a port velocity of 3 m/s. Any other specs I should take in consideration?

[IMGDEAD]https://haja.smugmug.com/Subwoofer/n-rqdxgV/i-LBBJLpC/A[/IMGDEAD]
 
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NoDad

Member
2017-10-06 1:54 am
I guess the link in post #16 didn't work. I'm trying again. (Hopefully) below is the screenshot of the WinISD for the two sub projects I created. The green graph is an 8" ported design. The blue is a 10" sealed.
 

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Using them as stands limits the measurements to max. 12x12x26" (30x30x66 cm), which equals a net volume of around 37 liters.

For the ported design it shows a port velocity of 3 m/s. Any other specs I should take in consideration?

3 m/s ?! Maybe at 1 W.

OK, the referenced Dayton Audio RSS265HF-8's classic vented alignment is ~ 36.86 L 'net', so could be a little less to fit the driver, but to get the performance it's capable of requires 350+ W and a large, long vent to keep its vent mach reasonably low [< 20 m/s] which requires nearly 20 L alone, so if you can run the vent outside the cab............[at ~56" mostly rhetorical].

Regardless, With inexpensive DSP, such tiny cabs are best sealed with as big and/or as many drivers will fit and EQ it to best blend in room.

Import the Hornresp file to view, copy, modify, etc.; omit the vent and it looks good sealed with modest DSP. A 'stereo' pair sims near THX reference from 30 Hz and if there's enough room/boundary gain, then could get down to its 20 Hz reference.

GM
 

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NoDad

Member
2017-10-06 1:54 am
3 m/s ?! Maybe at 1 W.

OK, the referenced Dayton Audio RSS265HF-8's classic vented alignment is ~ 36.86 L 'net', so could be a little less to fit the driver, but to get the performance it's capable of requires 350+ W and a large, long vent to keep its vent mach reasonably low [< 20 m/s] which requires nearly 20 L alone, so if you can run the vent outside the cab............[at ~56" mostly rhetorical].

Regardless, With inexpensive DSP, such tiny cabs are best sealed with as big and/or as many drivers will fit and EQ it to best blend in room.

Import the Hornresp file to view, copy, modify, etc.; omit the vent and it looks good sealed with modest DSP. A 'stereo' pair sims near THX reference from 30 Hz and if there's enough room/boundary gain, then could get down to its 20 Hz reference.GM
Sorry for not responding sooner. Work has just been incredible this week and I've been to exhausted to think about this.



You're right, it was 1 W. I hadn't even played with this power level before. I just tried 50 W and the velocity was almost 20 m/s. This ported box was using a Dayton Audio RSS210HO-8 8" Reference HO Subwoofer 8 ohm with a volume of 20 liter with a 2.5" round port. I guess I need to do some more calculating. Thanks for pointing this out. What wattage are you supposed to use when figuring this out?


For the 10" Dayton driver I was planning a sealed box as the volume is too large for a ported. A sealed box is sounding like a better and better choice. Especially since it's my first try with a DIY sub. Although I liked the frequency graph of the 8" ported better.



Any good DSP capable amps to suggest?