Home Theater Forum and Systems banner

Build thread! Unknown 12" Sony driver...

13K views 40 replies 6 participants last post by  favelle 
#1 · (Edited)
Well, I decided to start a new project. Not for my home theater, but just for fun. Had an old 150W Sony SA-WM500 sub. A 12" home theater sub bought back in 2000 when I thought low frequency meant 25-30hz (LOL). Well the sub has been silent for about 5 years now so with all my spare parts lying around I decided to "rebuild" it to try and squeeze some more performance out of it.

This may end up turning to as there was no way to find the T/S parameters of the driver, but nothing ventured, nothing gained. If it works out, I'll likely give the sub to a family member that has been slowly getting into home theater after being over a couple times. So it will go to a good home if it works.

So here's the driver:





12". Nothing special. Certainly not what we extreme DIY sub freaks are used to. But again, this is just a fun PROJECT. Nothing serious.

Next up is the parts list. All spare parts from my basement, just going to waste. This will be an 80L build. 16" diameter Sonotube cut to 27" long will form the main cabinet. 4" PVC cut to 21 inches will be the port. This will give the enclosure roughly a 21-22hz tuning. Probably more than the driver can handle, but we'll be careful. Or NOT! Ha ha, if the driver fries, it fries. Part of the fun.



 
See less See more
4
#3 ·
Thanks man. Yeah, searched around the net for days for info on the driver....couldn't find a thing. We know it came from a 1 cub ft box, tuned to 40hz, being fed 150W @ 6 ohms. So it will be interesting to see how it performs, LOL. Got my SPL meter ready. Got the endcaps cut, port tube cut, sonotube cut,.....just got a few minor things to do before I put it together for some test runs!
 
#5 ·
40 hz tune isnt that low by todays standards, and the original box was small. Your tuning twice as low and putting it in a box almost 3 times the size. I'd make sure you dont put any more than 100 watts (which is even probably pushing it a little) into this, and use a HPF if you have one. I get the feeling there is a good chance you could fry this driver otherwise :devil:
 
#6 · (Edited)
We're using the same amp that came with the sub, so chances are, it already has a HP filter on it. The build literally will cost no money, its purely for fun. If it works out in any way better than a HTIB sub or $250 box-store sub, then I'll gladly give it to someone to get his home theater addiction started, LOL!
 
#9 ·
Yeah, the hope is the amp's HP filter was set a little lower than the tuning of the original box and also the driver having a lower Fs than what it was tuned for. If those 2 things are true, we can definitely squeeze a little more out. How much is up for debate and that's what the testing will be for. I'll likely start at -12db below reference and work from there. If I can get it to out put flat to 30hz, it will be better than it was. And if it makes some kind of noise at 25hz or even 22hz, then its all gravy. Part of the fun!
 
#10 ·
Endcaps cut (except hole for 4" port). Just rough cut with a jig saw. No sanding or anything. Trying not to do extra work until I know it sounds ok, even though a 22hz tuned box will be useful and I'll likely find a driver amp/combo for it eventually if this doesn't pan out.

As it is, I have access to a drill press that fits hole-saw bits, so I am going to use that to cut the port hole in the top endcap tomorrow. I may offset the port like it is in the 2nd pic to give more clearance from the driver. We'll see.

3rd pic shows a counter-sunk screw. I did 2 of these in the port endcap because it wasn't staying properly and my clamps are not available to me right now. Everything about this build spells "weekend warrior". Literally anyone could make this sub. That's kind of the goal as well. For literally a fraction of the cost of a box-store sub, better can be built!






 
#11 ·
Pic of the bottom endcap sitting in place. Just wanted to see how it fit. You can see the driver flush-mounted inside. Fits like a glove. Which is good. Air leaks will NOT be tolerated!!!

In this pic, the sub is upside down. I am searching for the dowling for the legs.

 
#12 ·
Some more work today:

First up is the pilot hole for the port tube hole. Needed to go all the way through because its going to be 3 layers of 3/4" MDF so I'll have to do two passes with the hole saw. One pass from each side:



Port tube (4" PVC) fits like a glove!!



Only problem, port is too long! I wanted at least 1.5 times the diameter of the port clearance from the driver magnet. Well its closer than that. Like 3.75 inches away. So I had to cut 4 inches off and now I'll get either a 45 degree elbow or a long-sweep 90 degree. Precisely why I offset the port from the center. Just in case. ;)



Lastly, I counter-sunk the screws that will go into the 1" dowling that will act as the cab's legs. Should work out great!

 
#13 ·
Port tube length HELP!! Ok, so I got a "long sweep" elbow so I could fit my 21" 4" PVC port. Only problem is, the elbow is LONG. How do I calculate my port length now? Surely the elbow is adding length so its not going to just be 21" of straight tube + the elbow?

Any opinions?

21" port tube cut into 17" and 4" pieces:




With the elbow in place. Look how much longer it makes it!

 
#15 ·
Use a tape measure and measure the length along the inside of the bend, then the length along the outside of the bend. Subtract the two numbers, then add half that difference to the length along the inside of the bend. This gives you the length along the middle, which is what you need.
 
#17 ·
Well, everything is cut and ready to go. Here's the cab with the port endcap in place and the driver endcap with driver beside it!






And here it is all together. This is just a dry-fit. Going to tape all the seams and then fire it up for a few test tones and demos. I don't want to do all the finishing work only to have it sound like poo. So fingers crossed. Got the SPL meter all charged up and my demo material lined up, ready to go. Sometime tomorrow, I'll be givin' it the trial run! :)

 
#18 ·
I remeber the Sony SA-WM500 they were very popular for a cheap subwoofer. I know a few people who extended the port to get a lower tune.

I can't remember if the amp has a high pass filter on it, as long as it is not too resctrictive I think this subwoofer will very much surprise you with its output.
 
#19 · (Edited)
Right you are brother!

Ran it through some tests today and I was hella surprised!! I couldn't believe it was the same sub. This was just a dry fit with air leaks everywhere, no damping material inside and the port was just sitting in the hole, not quite fitted properly. So it wasn't very scientific....more just a gauge of whether or not I was wasting mine (and yours!) time. Well, I'm confident that I can now "finish" the sub properly.

I first ran the test tones at -8dB below reference. I normally run my subs at -4dB but I wanted to be careful with this one. I don't mind frying it, but I wanted it to last longer than 30 seconds, LOL! This is what I got:

60hz = 94.0dB
50hz = 84.1dB
45hz = 94.3dB
43hz = 97.9dB
40 hz = 94.6dB
36hz = 92.6dB
35hz = 93.0dB
33hz = 91.4dB
32hz = 91.9dB
30hz = 88.3dB
20hz = 72.9dB

I couldn't find all my 20's test tones so there's a bunch of missing data. Clearly the amp has a HP filter on it. So, when everything is all sanded and finished, I am going to run a test through my 500w plate amp with NO HP filter. Should give me a better indication. But aside from all that, this little bit of work has produced a sub that literally crushes the earlier, commerical store-bought configuration. Its night and day. I am also going to raise the tuning a little bit. I think 21hz is pushing the limit of the driver. I am going to try 24hz and see if that hits the sweet spot. Either way, should make an excellent "little" 12" sub for someone for movies, games, or music!
 
#21 ·
Thanks man! :)

Clearly, the driver can handle more. It didn't even seem like it was stressing. Its the amp that's holding it back. Even a 240W plate amp with no HPF would be better. But that said, this totally rumbles all kinds better than the previous configuration. Makes sense though. 1cu ft tuned to 40hz vs nearly 3 cu ft tuned to 22hz. LOL! No contest!
 
#25 ·
Thanks man. Ran a 100hz to 20hz sweep at reference today and it hit 110.3 on the SPL meter. The old sub would NEVER be able to do that. Not sure what the freq was, but the sub never bottomed out and the amp never clipped. I'd like to push it more. We'll see once its finished and sealed properly.
 
#27 ·
Its gotta be the size factor. Cost to ship, cost to build, cost for storage. No other sensible reason. The people in the market for a $250 sub aren't likely to want something 3 feet high and 80 lbs!

But yeah man, I think the driver is capable of more. How much more, I'm not sure. When its fully finished, I will temp hook up my 500W BASH amp and run some more vigorous tests. If the results are again night and day, then I'll have no choice but to swap out the amp for a 300W BASH or something like that. It really depends on who the sub ends up going to. If they guy wants to put some money into it, then I have no problems ordering and installing a new amp. But I'm not keeping the sub, so I wouldn't be buying a new one for my self.

I'll keep you updated. I have fully sanded 1/2 of one endcap and I have located some black felt for wrapping the tube. So all that's left is to finish sanding the endcaps, lining the damping material in the sonotube, and then assembling/sealing/painting. Should be good!
 
#28 ·
Well, got some serious painting done today. Nothing fancy, just Krylon acrylic. This is literally the ONLY thing a had to buy for this build!

Port endcap in place, painted:



Driver endcap painted:



Legs painted:



All was fine and dandy. 3 coats on everything. Decided to try out a new clear coat.....BAD IDEA. It reacted with the paint and HUGE "orange-peeling" everywhere. Basically ruined the port endcap. Luckily, it was the only one I experimented on. So the sub is basically built, but the port endcap will have to be re-sanded and painted again. Tomorrow is sunny so hopefully by tommorrow night...it'll be DONE!
 
#32 ·
Port endcap is painted. Done. Its SILKY smooth. Just waiting for it to dry. Its 2pm now. By 5pm, this thing will be done and together. I'll leave it for 24 hours to fully dry some more, then we haul it to the theater room for some testing goodness!!!!!!!

 
#33 ·
Well folks, done and done. Here's the final build pics! Some minor stuff to be done, but as I am probably passing this sub along, I'll let the next owner do the final cosmetic stuff.

Securing the port tube. Yes it fits tight, like a glove, but I always get paranoid that eventually over time it'll fall and hit the driver, LOL!



The sub, all secured, sealed and together waiting for the port covering:



Material lined up to cover the sonotube:




All done!! Going to let the caulking dry for 3 hours.......then its time to fire it up and let the action fly!!!



 
#34 ·
Ok, ran some real-world tests on this bad boy. SPL meter in hand, I played the following Blu-ray test scenes:

1) Kung Fu Panda: Tai Long escape scene. Slo-mo crossbow had my eyes opening WIDE. I had to replay it twice to see if it was actually sounding this way. Fast-forwarded to the slow motion climb up the falling rocks....WOW! Finally, I skipped to the end to the "skiddoosh" scene. 104dB.....and this was running -6 from reference with the old 150W amp that likely has a 30-40hz HP filter on it!!

2) Transformers Revenge of the Fallen: Opening scene with the Primes. The bass sweep when they show the seeker being built. WOW.

3) Terminator Salvation: Gas station scene. BOOM....BOOM!

4) Transformers: IronHide flip. Hit 108dB.....I couldn't believe it. From this sub? What would it sound like if I swapped the amp for a BASH300 with the HP disabled? Amazing.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top