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Considering a DIY Sub - got a favorite?

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Dec 24, 2019
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#1
I built a pair of Zaph ZD5 speakers a couple of years ago and finished the matching center channel speaker a few months ago. After that, I was thinking I was done building speakers for a long time. They're always WAY more work than I inticipate and I've got plenty of other distractions.

I've been considering a second subwoofer and have been eyeing a Hsu Research ULS-15 mk2 which just happens to be on sale now for $729. It would join the Hsu VTF-1 mk2 I already have.

And then I started clicking around seeing comments like, "DIY subs provide by far the best bang for the buck!" so I'm being lured back into considering a build. Clicking around I found lots of views and opinions and specs but I really don't want to do all the up-front research. I would prefer to just use an acclaimed design that I can just order the driver, amp, etc. and build the cabinet myself. I like the ULS-15's relative compact sealed design vs larger ported beasts so something along those lines would be preferred but I'm open to suggestions. Budget would probably be <$750. I'll be using Audyssey so I don't know that I need DSP but, again, I'm open. I have a wide open home floorplan and listening is a mix between music and HT.

Got a favorite design you can link me to?

Center channel speaker-1-sm.jpg
 

digitalfrost

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#3
I really don't like bass reflex bass tubes, but I appreciate the added performance, especially in the bass, of the drivers rearward generated sound, so passive radiators it is. I would go for something like this http://www.troelsgravesen.dk/26W-4558T00.htm they come in 10" and 12" variants with fitting passive radiators and you can choose between a cube with the passive radiator at the side or built a "tower" with both chassis on the front. Volume required is not overly large so these can be put into any shape/form box you see fit.

That said. Building subwoofers is really easy compared to anything else in speakers. Since all the performance happens around the resonance frequency and the room influences a lot below Schröder anyway, simple simulation programs to a really good job. So think about how much box volume you want and what your loudness requirements are, find a chassis you like, simulate it, and built away.
 

digitalfrost

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#4
You could replace your speaker stands with subwoofers. You need them anyway right. If you find a good 6"/7" chassis you could put two per side on the front given the volume the stands already provide, with the stands keeping the current width. Or put a bigger woofer on the side, maybe even back to back if you find ones that are shallow enough. Or if you're willing to go with bigger stands, anything is possible.
 
OP
MrPotatoHead
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Thread Starter #5
V.B.S.S

or anything with a Dayton Ultimax 18!
I have seen the Dayton Ultimax 18 mentioned quite a lot so that says something. And the Parts Express bundle is appealing and surprisingly compact at 23" x 20" x 20.75". I've always been a little snobby about flat pack cabinets but this seems like it would satisfy my desire to build something without putting in too much effort. Interestingly their bundle price is more than the total for individual pieces so I sent them an email. I've got a design idea in my head for some stained Baltic birch ply on the sides...

I really don't like bass reflex bass tubes, but I appreciate the added performance, especially in the bass, of the drivers rearward generated sound, so passive radiators it is. I would go for something like this http://www.troelsgravesen.dk/26W-4558T00.htm ...

That said. Building subwoofers is really easy compared to anything else in speakers...
Thanks for that. Now that I've read a little more, it does appear that it's just a driver in a box with an amp strapped to the back!

You could replace your speaker stands with subwoofers...
It turns out that's an illusion. The inerior of the cabinet extends below the bottoms of the curved side panels and the crossover housing is below that.
 

bigjacko

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#6
@MrPotatoHead For subwoofer flat pack is not a bad thing because subwoofer box is so hard to get wrong. As long as dimension is right and box is rigid enough it is good enough, there is not internal standing wave and diffraction to concern about. If you have the hardware you can also do multiple smaller subwoofers to get the room modes out., it is way better than single expensive high quality sub.
 
OP
MrPotatoHead
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Thread Starter #8
I really like my Overdrive10 project!...
Ooh, this is interesting and I love the tiny size. I read your threads on P-E and DIYAudio. Have you made any discoveries or do you have new ideas since the original design?

Re. tuning you wrote: "Just remove the amp and hook up the driver to a T/S generator and run a sweep. The dip between Z peaks is your tuning freq. Or, just use the mass as I described in the layout." Does that mean below and above 50Hz there will be resonant peaks were the PR has greater, obvious excursion?

It appears that the Yung amp with boost at 25Hz is no longer avialable. I think you noted that that boost might not be necessary. Ya?

Thanks for the tip.
 
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#10
Yes it is:
https://www.parts-express.com/yung-...-amplifier-module-with-6-db-at-25-hz--301-514

I am still using it as designed and stated. Make sure you are looking at the final graphic, as the length was initially misstated. It is 15.5" long total, including the rear-recessed wall for the amp mount.

Below and above the 50Hz tuning of the PR will be higher impedances, but not necessarily resonances. In a bandpass, the tuning is basically close to the midpoint of the design, and is the minimum impedance magnitude.
 
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#11
oh- and the boost really is needed for the extension unless 35 Hz is all the lower you want to go. Since I use mine for music and HT, the extension is required.
 
OP
MrPotatoHead
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Thread Starter #12
Yes it is:

Make sure you are looking at the final graphic, as the length was initially misstated. It is 15.5" long total, including the rear-recessed wall for the amp mount.

Below and above the 50Hz tuning of the PR will be higher impedances, but not necessarily resonances.
Ah, thanks, I somehow ended up on a restocked amp page.

To verify, the internal dimensions are 11-1/4 x 11-1/4 and the space behind the driver is 7-3/4 inch deep and the space between the front of the baffle and the rear of the PR panel is 4 inch. Correct?

Finally, are you measuring the impedances below and above 50 Hz by looking at the current output from the signal generator?

Thanks.
 
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MrPotatoHead
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Thread Starter #15
wow. the black part totally look like stands.
The interior cabinet extends below the curved side panels and the crossover housing is in the bottom. Here's an old cross section view - that divider near the bottom didn't happen so the crossover housing goes all the way to the bottom to space the two boards farther apart.

zd5-floor-pair-cross-1-sm.jpg
 
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#16
Yes- you are correct in dimensions.

I use a WT2 device to measure impedance. You can make a limp-jig to use ARTA-Limp to measure the impedance if you don't want to purchase something like a DATS V3. These devices all work by using a USB outboard soundcard and software to translate to the graph.
 
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#18
The interior cabinet extends below the curved side panels and the crossover housing is in the bottom. Here's an old cross section view - that divider near the bottom didn't happen so the crossover housing goes all the way to the bottom to space the two boards farther apart.

View attachment 96646
Isnt it a bit oversized for that woofer? It probably helps the bass extension.
 
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#19
Rythmik has servo kits. I've been investigating their F12 dual subwoofer. You can split them into two separate ported or sealed and use the one amp. A hair under $1k for the pair (normally one f12 would be $1k)
 
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