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-   -   Bobbo's sub build (pics) (http://www.diyaudio.com/forums/subwoofers/219815-bobbos-sub-build-pics.html)

bobbobobbo 16th September 2012 05:49 AM

Bobbo's sub build (pics)
 
Finally finished up my project. Special thanks to everyone that helped me out.

Figured I'd post some pics. It's a Peavey Low Rider 18" paired with a bridged Behringer EP2000. It's a 5.5 cube box tuned to around 32hz.. It's purely for music and parties.

I did all this on my porch and party room, definitely not a master wood worker or have done audio work like this before. Yes I know things could/should have been done differently but turned out quite nice. Hits decent, though I think it overall needs some adjusting.. (will touch on that at the end)


http://cdn.avsforum.com/f/f7/350x700...75ea3d3_1.jpeg
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
http://www.avsforum.com/content/type...350/height/700
4 cans of truck bedliner. Still have to put on the grill guard.


As I was mentioning earlier I think it needs some adjusting.. it hits hard, but not nearly as it should. Some songs it barely hits at all... (when my old sub would be going hard) It just sounds empty on a lot of bass heavy songs. I currently have the amp set up as follows.

Clip limiter on
Low cut filter 30hz (as opposed to 50hz)
Low cut filter on
Bridge mode on

The signal is coming from a home theater receiver "subwoofer out" through a thick subwoofer rca cable into a 1/4 mono TRS adapter, into the amp. The amp is hooked up to the driver using very thick copper stranded speaker wire.

Not sure where the issue is.. (maybe amp settings wrong / perhaps I need to use a speakon connector / maybe the box is at fault / maybe it's tuned all off)

weltersys 16th September 2012 06:38 AM

Quote:

Originally Posted by bobbobobbo (Post 3166749)
Not sure where the issue is.. (maybe amp settings wrong / perhaps I need to use a speakon connector / maybe the box is at fault / maybe it's tuned all off)

Bob 3,

Testing the box tuning would be the way to see what is happening.
Put a silver or white dot on the cone, sweep a sine wave (or down load sine waves if you dont have a tone generator) around your predicted tuning, the cone will have minimum excursion at Fb.

32 Hz Fb is pretty low for a Peavey Low Rider in that small of a box (it will have a very rolled off LF response), to get some kick out of it you should raise the tuning to around 38 Hz, if your box actually comes in at 32 Hz Fb, saw off a bit of the port shelf and test.

Art

bobbobobbo 16th September 2012 07:18 AM

Quote:

Originally Posted by weltersys (Post 3166776)
Bob 3,

Testing the box tuning would be the way to see what is happening.
Put a silver or white dot on the cone, sweep a sine wave (or down load sine waves if you dont have a tone generator) around your predicted tuning, the cone will have minimum excursion at Fb.

32 Hz Fb is pretty low for a Peavey Low Rider in that small of a box (it will have a very rolled off LF response), to get some kick out of it you should raise the tuning to around 38 Hz, if your box actually comes in at 32 Hz Fb, saw off a bit of the port shelf and test.

Art

Thanks Art! I shall put on that white dot and do the sweep.

Should the low cut (high pass) filter be set to on? 30hz or 50hz? Maybe that has something to do with it also.

32hz must be way too low.. I agree. I'm just looking for that chest pounding bass. Sound quality is nice, yet not as critical. I have no problem sawing that shelf. Further, I have a ton of polyfil, I could stuff the crap out of it..? Likely gain an extra cube.

Ps why 38hz? Balance between quality and output?

weltersys 16th September 2012 03:05 PM

Quote:

Originally Posted by bobbobobbo (Post 3166803)
Thanks Art! I shall put on that white dot and do the sweep.

Should the low cut (high pass) filter be set to on? 30hz or 50hz? Maybe that has something to do with it also.

32hz must be way too low.. I agree. I'm just looking for that chest pounding bass. Sound quality is nice, yet not as critical. I have no problem sawing that shelf. Further, I have a ton of polyfil, I could stuff the crap out of it..? Likely gain an extra cube.

Ps why 38hz? Balance between quality and output?

Leave the low cut (high pass) filter "off" while determining Fb.
Polyfill will reduce output.
"Chest pounding bass" is generally 60-120 Hz, 32 Hz is more "pants leg flapping", a 38 Hz tuning in your box should give you a bit of both, but the low tuning you (may) have sacrifices both.

bobbobobbo 16th September 2012 07:41 PM

Quote:

Originally Posted by weltersys (Post 3167151)
Leave the low cut (high pass) filter "off" while determining Fb.
Polyfill will reduce output.
"Chest pounding bass" is generally 60-120 Hz, 32 Hz is more "pants leg flapping", a 38 Hz tuning in your box should give you a bit of both, but the low tuning you (may) have sacrifices both.

Will leave filter off. Should I leave off indefinitely? If not, 30hz or 50hz?

Polyfill will reduce output? Assuming I cut the port down, polyfill lined should make the enclosure a bit larger, helping overall? If still tuned to 38hz. Or not worth it.


Here's my other thread if you have some time to reference. They're claiming some other things. Bobbo's sub build (pics)

Will do the fb test right now.

Thanks again so much.

bobbobobbo 16th September 2012 08:13 PM

Tuning comes in at 33hz-34hz. I definitely don't want to take it all apart for only a few dbs. Perhaps I'm not getting enough signal as others have mentioned.

turbodawg 16th September 2012 09:15 PM

Personally not a huge fan of the wide slot port, it's not the same as a round port which is optimal. Look into that. Another reason I like round pipe ports is that they are easy to shorten/lengthen. To bring the tune up you're going to have to cut a section of that port from the inside. Also, if you have two 4" round ports, you can plug one or both to get better extension for movies, normal music listening, etc.

That's 3/4" mdf? It's not real stiff in a large panel like that, should have used plywood (cheap 5 ply birch is MUCH stiffer, also lighter). The MDF is absorbing energy.

The rod bracing is not effective. You need to get this properly braced. Get some 1/2" cheap birch ply, cut 1.5" slats to length and glue them lengthwise on the 1/2" side inside the box every 4 to 6" inch. Think of a 2x4 stud wall. This will massively stiffen it and result in more output. Also do similar bracing on the baffle behind the woofer. This can all be done by only removing the woofer. It will help, alot, especially with punch in the 50-100 hz range. Adding this wood will also slightly decrease internal volume, which will increase the tune slightly. Try this first, then shorten the port. Do NOT stuff it.

Another thing to consider is that your old sub was probably a common commercial design that had a peak somewhere in the 60-120 hz region. This will give you that bass presence in most pop music. It's also the reason for kick bins on some PA's. You've got a design that has a real nice gradual rolloff that should combine well with room gain and give a nice flatish response, but it's not a gut busting party sub. Based the plots you linked to and your goals, I would re-tune to at least 40 hz, if not 45hz. Or rework it to a couple 4" round ports that you can use to play with the tune.

Oh and yes, adjust the subwoofer gains on your receiver, just like you mentioned in your other thread.

Otherwise looks real nice and pro!!

turbodawg 16th September 2012 09:42 PM

Oh yeah...reading that other thread it looks like you're thinking about a new receiver. Most AV receivers are.....crap. If you're running just a pair of mains, consider a used pro audio powered mixer from somewhere like guitar center.

turbodawg 17th September 2012 01:41 AM

Also, make sure the box is well sealed and not leaking anywhere, that will cost you output.

bobbobobbo 17th September 2012 01:58 AM

Quote:

Originally Posted by turbodawg (Post 3167512)
Personally not a huge fan of the wide slot port, it's not the same as a round port which is optimal. Look into that. Another reason I like round pipe ports is that they are easy to shorten/lengthen. To bring the tune up you're going to have to cut a section of that port from the inside. Also, if you have two 4" round ports, you can plug one or both to get better extension for movies, normal music listening, etc.

Yeah I hear ya, unfortunately it's too late now. The slot port was much easier for me to do at the time. My next project (that sick 4 12"s you made) I'll do pipe ports.

Quote:

That's 3/4" mdf? It's not real stiff in a large panel like that, should have used plywood (cheap 5 ply birch is MUCH stiffer, also lighter). The MDF is absorbing energy. The rod bracing is not effective. You need to get this properly braced. Get some 1/2" cheap birch ply, cut 1.5" slats to length and glue them lengthwise on the 1/2" side inside the box every 4 to 6" inch. Think of a 2x4 stud wall. This will massively stiffen it and result in more output. Also do similar bracing on the baffle behind the woofer. This can all be done by only removing the woofer. It will help, alot, especially with punch in the 50-100 hz range. Adding this wood will also slightly decrease internal volume, which will increase the tune slightly. Try this first, then shorten the port. Do NOT stuff it.
Yes that's 3/4 mdf. It was the common consensus for what to use. I shall pick up some birch play and reinforce the walls. Pretty simple to do.

Quote:

Another thing to consider is that your old sub was probably a common commercial design that had a peak somewhere in the 60-120 hz region. This will give you that bass presence in most pop music. It's also the reason for kick bins on some PA's. You've got a design that has a real nice gradual rolloff that should combine well with room gain and give a nice flatish response, but it's not a gut busting party sub. Based the plots you linked to and your goals, I would re-tune to at least 40 hz, if not 45hz. Or rework it to a couple 4" round ports that you can use to play with the tune.
Exactly! It definitely hits. Don't get me wrong. Yet I just felt for what this is, it should really be chest pounding and deep. It sometimes sounds kinda flat and empty. Almost boomy.

I was afraid to tune it any higher because I wanted it deep and not boomy and many said I'll only gain a few dbs. Yet it seems that the greater the tune the more "gut busting" as you'd say. As yes this is a party sub. Maybe I just have my facts off.

I'll add bracing and look to reducing that port. I can fit a jigsaw in there. I have two 3" precision ports I can add on top of the slot port, if that works. (though I may have that backwards and need less portage..)


The box is very well sealed up. I have 5 standard jbl speakers to utilize, they use just standard speaker wire. I assumed I'd need a home audio receiver.


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