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post #1 of 13 Old 09-16-2016, 12:30 PM - Thread Starter
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Quad Sonosub LLT RSS390HO-4

It is time, after much time spent perusing these and other forums, to venture into the world of DIY speaker building. To keep things simple, I am starting with subwoofers. In a nutshell, I am wanting to build (4) Sonosub LLT subwoofers (hence the title). For starters I will give as much information about where I am in the build process, but I would love some feedback from more experienced builders prior to finalizing the design details. If I’ve got something all wrong, let me know. I will be taking the whole process pretty slow as I am obviously doing this for the first time. Also, I have a job and am a full time student. I’ll try to include a bunch of pictures to keep things interesting . . .

In terms of properly designing a LLT, I have attempted to keep everything from this write up in mind:

http://www.hometheatershack.com/foru...explained.html

Overview of important purchased materials:

(4) Dayton RSS390HO-4
Crown XLS 2500 amps
Mini DSP Balanced 2x4 (2-way Adv plugin, UMIK-1 and REW)
(2) 12’ Sections of 18” Sonotube
(2) 10’ Sections 6” SCH40 PVC Pipe

Overview of Design:

By pure coincidence, it seems that the RSS390HO works with nearly the exact criteria laid out in the above link . . . I had actually ordered parts before ever reading that write up.

Room Volume ~1900 cuft (odd shape, L-ish with an octagonal section)
Internal Volume (less port volume): <=250L
Tuning: 14 Hz (15 Hz would increase 1st port resonance if need be, currently 171 Hz)
HPF: I think inevitably I will require some filtering in case content reaches below 13Hz
80% movies/20% music.

I only have so much sonotube for (4) enclosures, so to maximize the internal volume of a given layout I wanted to reverse mount the driver. This orientation is more space efficient than a typical sonosub layout that essentially has a riser to keep a down-firing sub off the floor and would net about 7L in volume. Also, the Drivers have nice wire terminals built in, providing easy access outside of the enclosure. A reverse mount should also provide better cooling to the coils . . . though I don’t think I will be pushing them that hard.

Side note: The Dayton HO were chosen over the HF to produce relatively smaller footprint enclosures, which is more of a concern with (4) subs . . . In this way I was hoping to end with more even distribution of bass across all listening positions rather than absolute lowest extension.

Otherwise, the construction will be pretty typical with big round endcaps and flared ports. If you have used the “Sonosub” design software, the animation provides an excellent representation of what these things should look like. Software: http://www.subwoofer-builder.com/sonosub.htm

I was thinking I might also put in an internal brace to hold the port inside, rather than have it’s only support be the top cap. This would also provide a means to separate any stuffing from the driver.


This is what WinISD predicts without a HPF, excursion will always be an issue below tuning . . . so I assume I should plan on a HPF just in case?


This is the curve with a 2nd order butterworth HPF at 15 Hz, this seems to still increase group delay around 20 Hz . . . I don't know how much on an issue it will be. Btw, when I was playing around with WinISD I have the signal set for ~280 watts.


Initial Questions:

Will reverse mounting the driver actually produce any noticeable variance? I would assume the backside of the driver actually has slightly less Sd than the front, equal or less than the area of the dust cap . . . would this cause the port output to be greater than WinISD predicts? Or is the difference negligible?

How much of an issue will 1st port resonance of 170hz be with ~80 Hz crossover? Pushing the tuning up seems to help a lot with this, I am just wondering which is more important: Lower tuning or port resonance?

Given that LLT designs plan ahead for room gain, is it worth while to do preliminary testing using REW and my existing subwoofers to determine where room gain begins and attempt to fine tune the enclosures to align with this information?


Current Setup:

Vizio M60-C3
Denon AVR-910W (MultEQ only)
2x Dayton SUB-1200
2x Fluance SXHTB speaker systems:
Center: SXC Center
FR/FL: Classic Elite Series 2-way
SR/SL: Classic Elite Series 2-way
SBR/SBL: SXSS surround speakers

Quickie Review of current setup:

Sub-1200s are being replaced obviously, but were great. For a total of $240 shipped, the SUB-1200s really are value kings, easily whomping any “HT in a box” subs. The SUB-1200s did most everything I asked until they approached the infrasonics, where they promptly called it a day and went home. I have a very oddly shaped room, which is why I am doubling up on subs, and increasing size/power. When in doubt, power out?

The classic elite floor standing speakers are the shining gems of the main speaker package. Similar performance to something along the lines of the Klipsch R26F for less money, and you essentially get the smaller surrounds to fill out a 7.1 for free. The floor standing units actually impressed me, the surrounds get the job done. As a package the biggest complaint is the center channel. The center, in no way, keeps pace with the larger units. I will most likely replace the center with something from DIYSG in the future, as the hobby continues to grow.

Initial Pictures: (I use a 32" monitor, if my pictures are still too large for some people let me know)


These are the spring terminals I figured I could use with a reverse mounted driver. They have seemingly stiff springs in them.


Topside of a driver, if you somehow haven't ever seen one. 3 more in the boxes behind.


Something I learned during this process: the only place in my house that will fit 12' sonotube was the living room. These things are tall . . .
Also, for those of you with access to Menards, at least in northern Illinois they can order many different sizes of Sonotube.
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post #2 of 13 Old 09-17-2016, 11:48 PM
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I wouldn't worry too much about the port resonance. I've seen tests in this forum where stuffing the enclosure nearly eliminates the port resonance, though at the expense of 2-3dB in peak output. Can't recall which thread or post where I saw that...

Mike
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post #3 of 13 Old 09-18-2016, 09:28 AM
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Seriously digging those chicken things seen in your last pic

Those SUB-1200s are great for the money. Where are you located? Have you posted those in the Classifieds yet?

Looking forward to this build!

------------------------------------------------
Receiver : Denon x5200
Front Stage : L/R - Statements by Jim Holtz
Surround Speakers : Klipsch RF-82II x 4 / RP-280F x 2
Subwooferage : 6 UM18/4 HT18 Subwoofer Log
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post #4 of 13 Old 09-18-2016, 06:41 PM - Thread Starter
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Quote:
Originally Posted by mhutchins View Post
I wouldn't worry too much about the port resonance. I've seen tests in this forum where stuffing the enclosure nearly eliminates the port resonance, though at the expense of 2-3dB in peak output. Can't recall which thread or post where I saw that...

Mike
Ok, good to know. I will eventually have to play around with stuffing and/or damping, but it's good that it can be effective.

Quote:
Originally Posted by bgtighe23 View Post
Seriously digging those chicken things seen in your last pic

Those SUB-1200s are great for the money. Where are you located? Have you posted those in the Classifieds yet?

Looking forward to this build!
If you look around that picture some more, you might find ducks as well

I am in northern Illinois, but for the moment the Sub-1200s are not in the classifieds. Until I get these built they are my only subs. I will most likely be using them to get a feel for using REW, determining acceptable sub placements, playing around with types/amounts of stuffing, etc.
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post #5 of 13 Old 09-18-2016, 07:09 PM
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What made you decide on this particular driver?

------------------------------------------------
Receiver : Denon x5200
Front Stage : L/R - Statements by Jim Holtz
Surround Speakers : Klipsch RF-82II x 4 / RP-280F x 2
Subwooferage : 6 UM18/4 HT18 Subwoofer Log
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post #6 of 13 Old 09-19-2016, 11:12 PM - Thread Starter
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A bunch of things led me to the RSS390HO, one of which was probably inexperience . . . but otherwise my other thoughts follow:

I have a very oddly shaped room, and I am concerned with the distribution of bass across the listening positions. The plan was to build 4 subs, so the individual driver cost had to be on the lower side. The quantity of subs pushes out most 18" options, though the PA460 seems be very popular now . . . and is a driver I never really knew anything about.

The Dayton reference series seemed to have a very good reputation and had been used successfully in many DIY projects. My intention had always been to pursue sound quality over sound quantity (ultra high dB), the reference series appeared to be well balanced drivers . . . having less excursion than some other options, but more control over what excursion it offers at its price point. This was my interpretation anyways.

But if I wanted good sound quality, why did I choose the HO instead of the HF? This was a result of needing (wanting) 4 subs and not being in a dedicated home theater. Size constraints are a concern, and this is no small issue when I will be trying to place 4 units. The dual voice coil, and lighter cone of the HF would have provided slightly more low end extension and perhaps greater fidelity . . . but this would come at the expense of needing much larger enclosures. The four layer voice coil, and higher moving mass of the HO offered comparable output while needing a smaller enclosure. Aiming for a similar configuration, the HO and HF produce very similar frequency response, so I traded some sound quality for a smaller footprint. If using the HO allows for 4 subs instead of 2, I may still end up with better in room performance than I otherwise would have. While we are talking about size constraints, an 18" driver would have made for a much wider footprint, and width is much harder for me to accommodate than height . . . and again for the price I would be looking at 2 units instead of 4. Here is what WinISD produces for HO vs HF with a 14 Hz tune, both drivers powered until they touch their respective Xmax, HO in 250L and HF in 450L enclosures. In the same size enclosure, HF seems to have less low end than HO . . . a 450L enclosure would require 22" sonotube to fit under 8' ceilings, and would take up enough foor space to fit 2 more HO units:


The colors are a little messed up, but the HO is yellow and HF blue

While I am not in a dedicated HT, it is a closed off environment (~1900 cuft) where I should have a reasonable amount of room gain. My understanding is that the LLT design accounts for room gain, aiming for a 4dB/octave rolloff before tuning, unfortunately it appears I may only achieve 2dB/octave with a 14 Hz tune so I may still end up a little "hot" in this regard.
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post #7 of 13 Old 12-30-2016, 01:34 PM - Thread Starter
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The Build Begins

I am on winter break now, so the building has commenced. I have a friend coming to visit late next week, the plan is to have these things functional by then. Most likely the decorative processes will not take place until warmer weather lets me get the sprayer out.

I have decided on going with the conventional layout with the driver positioned facing out, and no internal bracing.

All of the initial circles are the largest ones from which the rest will be cut from. In total there will be 16 larger than the tube diameter, and 16 of the internal tube diameter.




I started cutting outside because I was worried about dust accumulation inside the garage, however this wasn't too much of a problem. With a 1/8" bit, the vacuum, and the fact the a bunch of the dust gets trapped in the kerf . . . dust is pretty well contained. I am sure something is wrong with my cut/feed speed that prevents the dust from getting pulled out, but the cuts are clean so I am happy. Btw, we have recently had some nice winter days here in Illinois, the temperature outside was about 33F.



Speaker of 1/8" bits, I got a 10 pack of bits from amazon (sold out atm, but listed below) that have been working wonderfully. I have the router (DW618) set at about 20k RPM, and I approximated my feed speed at about 150 ipm. As far as life span goes, doing 3 cuts per circle to get through 3/4" mdf, I made ~270' of 1/8" x 1/4" grooves before I managed to snap one. The cut quality was still acceptable, it was most likely user error, but I find this rate to be fine given that they cost ~$1 each.

The bits, https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Also, the reducing sleeve I am using to bring the 1/4" collet down to 1/8". The only issue is that you have to press out any bits that you break

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1



The foam I will be using for the interior lining arrived, and is nearly the last of the materials that I need. It is simply 1" acoustic wedge foam. Purchased from here:

http://www.thefoamfactory.com/acoust...wedgefoam.html

I also have 3" 2.5 lb/cuft fiberglass for the top cap (not entirely sure how I will secure this yet)(Not Pictured).



I eventually moved inside, where I will complete all of the interior circular cuts. At this point, all of the largest cuts have been made. Most of the pieces that will only need port cutouts are done (8 done, 4 I forgot about). All that I really have left are speaker cutouts, and the round over piece for the internal end of the port.

Couple more phoenix connectors to make for the MiniDSP and it is all set.

Oh, and then I have to cut the sonotube and pvc ports . . . but those should be easy right?

More to come.
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post #8 of 13 Old 12-30-2016, 05:13 PM
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post #9 of 13 Old 01-03-2017, 11:45 PM - Thread Starter
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Quickish update:

A little behind where I wanted to be at this point, but I was at work all weekend.



Got the balanced minidsp all wired up. It is ready to be attached to some amps after I figure out how many volts my AVR puts out . . . though according to the minidsp manual, with an unbalanced input from the minidsp will take up to 1.8 volts on the 0.9 volt jumper before saturation so I would be surprised to be using anything else. The manual also says that it will output 2Vrms with an input of @Vrms, the crown amps have an input sensitivity of 1.4v . . . does this mean that even with the balanced minidsp my avr has to output 1.4v in order to use all the amps power? Or will augmenting the gains in the plugin resolve this?



Finished cutting out all the the pieces on Monday . . .



Got some of the endcaps glued up on Monday as well, but most were done on Tuesday . . . (definitely wishing I owned more clamps)



Here are the bottom caps after they can been glued up. I tightened down the carriage bolts that will be used to connect the legs/bottom plate in order to seat the top of the carriage bolt. I will reinforce the top seat tomorrow so that the bolts will not strip out in the mdf.



This is a picture of various positions of the top caps after gluing.

The far left one is the underside of the cap, the hole in the center will hold the port, which will be supported by 3" of mdf before the top flare. (Thick because it will not be braced anywhere else)

The middle view shows the top of the cap. The extra ring on the far right will be covered in speaker cloth and will be nested between the other two rings to cover the flare (which still needs to be cut.)

Tomorrow the sonotube and pvc will be cut to length. One section of pvc has already been cut in half on the tablesaw, which works very well for achieving square cuts.
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post #10 of 13 Old 01-04-2017, 02:10 PM
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Looking great so far! Sooooo much work cutting out all those disks and rings! I think you making the port exit in the endcap extra-thick is a very smart idea. I would assume you did a test-fit of the 6" PVC in that size hole before you did all that work?

I almost went with 8" PVC ports in the subs I'm currently building but changed my mind at the last minute b/c of previous issues I've had with PVC being out of round, or the hole is 1/32" too small and then you sand and it's 1/16" too big, etc.

Did you make the wiring harness for the miniDSP? That looks pretty sharp.
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post #11 of 13 Old 01-05-2017, 10:54 AM - Thread Starter
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Thanks!

Quote:
Originally Posted by michaelddd View Post

I would assume you did a test-fit of the 6" PVC in that size hole before you did all that work? . . . b/c of previous issues I've had with PVC being out of round, or the hole is 1/32" too small and then you sand and it's 1/16" too big, etc.
I did do some test fits. The out of roundness was not a huge issue for me, the tube I got is not technically solid pvc. It is a pvc foam core manufactured to meet certain rigidity standards, but does not support actual pressure. I cannot flex it by hand, but when I put all my weight (185 lb) onto it there was no problem getting it to deform just enough to slip into the the top cap. All 4 layers of mdf were slathered with 100% silicone caulking to provide an air tight seal and for additional strength. (Which really isn't required, with as tight of a fit as it was there is nothing I or a subwoofer is going to do to pull it out.)

Details on the pipe I am using. (IIRC the wall thickness turned out to be 5/16")
http://www.charlottepipe.com/Documen...werps50_LF.pdf

OH! Also, when I was gluing the top cap together, I used to small section of the pvc pipe to align all of the mdf circles. Had to hammer it out before I put the flare piece on, which only needed to be near centered as I will be using a flush trim bit and 3/4" round over to actually shape it to the pipe.

Quote:
Originally Posted by michaelddd View Post

Did you make the wiring harness for the miniDSP? That looks pretty sharp.
I did. MiniDSP didn't offer connections when I bought my unit. I just did a search for XLR connectors and paired that with the info in the owners manual for the outputs. For the inputs I used the guide provided below:

https://seriousaudioblog.blogspot.co...s-for-2x4.html
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post #12 of 13 Old 01-05-2017, 11:51 AM
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Quote:
Originally Posted by MrChompenstein View Post
I did. MiniDSP didn't offer connections when I bought my unit. I just did a search for XLR connectors and paired that with the info in the owners manual for the outputs. For the inputs I used the guide provided below:

https://seriousaudioblog.blogspot.co...s-for-2x4.html
Nice work with the wiring, and thanks for that link, Chomp! I've been recently looking at the balanced 2x4 and kind of dreading connections... that makes it a little less daunting.
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post #13 of 13 Old 01-05-2017, 01:40 PM - Thread Starter
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Quote:
Originally Posted by OJ Bartley View Post
Nice work with the wiring, and thanks for that link, Chomp! I've been recently looking at the balanced 2x4 and kind of dreading connections... that makes it a little less daunting.
Glad it helps someone else, that link cleared things right up for me. If using XLR connectors, Pin #1 is ground/shield (woven copper wire around conductors), Pin #2 is positive (Red in my case), and Pin #3 is negative (white in my case). A quick google search for XLR connector turns up these Pin# locations; however if you order a full cable from monoprice and snip the ends off like I did, the connector itself will have the numbers cast into the plastic. For checking things, my cheapo multi-meter didn't have a continuity mode but resistance works just fine, as the resistance from pin to bare wire should be next to nothing. (0.1 ohm in my case)

Also from the MiniDSP Manual:

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