What Components for DIY Passive Sub? - AVS Forum
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Old 03-20-2013, 08:15 PM - Thread Starter
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Trying to put together a component list for building a passive sub (not radiator) to see if I might want to go the DIY route. Obviously I need a cabinet, driver, and binding posts, but what else? (I assume my receiver can handle the high bypass filter and I have an external amp for power) Do I just wire the driver to the binding posts?

David
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Old 03-20-2013, 08:27 PM
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- what amplifier will you use (how much power)?
- how large a box can you live with?
- budget?

Whatever you do, don't just start buying parts without some kind of plan. There are lots of good options, and lots of experienced folks here who would likely be happy to help.
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Old 03-20-2013, 08:39 PM
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Quote:
Originally Posted by crussader View Post

Trying to put together a component list for building a passive sub (not radiator) to see if I might want to go the DIY route. Obviously I need a cabinet, driver, and binding posts, but what else? (I assume my receiver can handle the high bypass filter and I have an external amp for power) Do I just wire the driver to the binding posts?

Yes, you build a specific box for a specific driver, wire the driver to a binding post/terminals in the cabinet, connect that to the output of the amp, which is connected to your receivers LFE output. That is all that is needed for a sealed build. if you go ported you will need either an amp with a high pass filter built in, or have an external one added to the chain between the receiver and amp (something like a miniDSP).
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Old 03-20-2013, 09:32 PM - Thread Starter
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Originally Posted by antisuck View Post

- what amplifier will you use (how much power)?
- how large a box can you live with?
- budget?

Amp - Amplifier from Emotiva. I don't need house shaking bass, so I wasn't planning on going high power. Would initially run off a UPA-500 (120 watts into 4 ohm) and later go to a dedicated two channel amp. Optionally, I have an old Kenwood KA-801 that has plenty of power I can use for a while.

Size - I'm looking to run a pair of the smallest boxes I can get away with and still get under 30hz. Right now I have an Energy S10.3 and would like to go smaller. The same cubic feet would be fine if I could put it a cabinet that was narrower.

Budget - I was looking at buying a pair of Outlaw M-8s before they ran out of stock, so something less than that ($500).


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Whatever you do, don't just start buying parts without some kind of plan. There are lots of good options, and lots of experienced folks here who would likely be happy to help.

That much I did know. Hence this thread. biggrin.gif

David
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Old 03-20-2013, 09:34 PM - Thread Starter
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Originally Posted by Jay1 View Post

...if you go ported you will need either an amp with a high pass filter built in, or have an external one added to the chain...

There's some key information I didn't know. I guess sealed it is.

David
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Old 03-20-2013, 09:51 PM
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Do you have two channels available from your amp for the sub? A pair of subs for under $500 would be pretty easy if you already have the amplification. Another consideration, a small box with very little power equals low output. Not that you cant have a very nice sub, just dont expect anything crazy
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Old 03-20-2013, 10:03 PM - Thread Starter
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Originally Posted by Jay1 View Post

Not that you cant have a very nice sub, just dont expect anything crazy

That's good to hear. Don't need anything crazy. I don't need to feel the bass. Just want to round out the bottom end of my 5.0.

Amplification is available and is outside this budget.

David
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Old 03-20-2013, 10:33 PM
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Originally Posted by crussader View Post

That's good to hear. Don't need anything crazy. I don't need to feel the bass. Just want to round out the bottom end of my 5.0.

Amplification is available and is outside this budget.

So, is that amp completely open for the sub(s), or is there only a single channel from it available?
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Old 03-20-2013, 11:19 PM - Thread Starter
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I can get whatever amp I need. That's a separate budget. I was thinking about adding a 2nd UPA-500 using 2 channels for rear surrounds, 2 channels for subs, and one open channel left. I also have a Kenwood amp that could power the subs. Or if neither of those works well, I can add some other two channel amp.

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Old 03-20-2013, 11:23 PM
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Quote:
Originally Posted by crussader View Post

That much I did know. Hence this thread. biggrin.gif
Excellent cool.gif Hope I didn't come off wrong, just seen one too many threads that start out "what do I need" and 3 hours later move on to "I have decided to go with [inappropriate driver x] and put it in [random box], what do I use to cut the hole?" biggrin.gif
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Old 03-20-2013, 11:43 PM
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Quote:
Originally Posted by crussader View Post

I can get whatever amp I need. That's a separate budget. I was thinking about adding a 2nd UPA-500 using 2 channels for rear surrounds, 2 channels for subs, and one open channel left. I also have a Kenwood amp that could power the subs. Or if neither of those works well, I can add some other two channel amp.

Alright, a pair of dual driver subs is going to get you the most bang for your buck. Four of these RS10's is a hair over $500

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-442

The subs are 8 ohm each, so the pair wired down to 4 ohms gets you a very nice sensitivity gain over any other 10" sub. Below is a slim baffled box option for a pair of woofers. Actual volume is about the same as the Energy sub.


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Old 03-21-2013, 01:17 AM
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Quote:
Originally Posted by crussader View Post

I can get whatever amp I need. That's a separate budget. I was thinking about adding a 2nd UPA-500 using 2 channels for rear surrounds, 2 channels for subs, and one open channel left. I also have a Kenwood amp that could power the subs. Or if neither of those works well, I can add some other two channel amp.

Why not use a proamp? Get a ton more watts for your sub rather than Emotiva. You could easily pump 700-800 watts into the sub with a proamp for the same price. Probably closer to 1000 now that I think about it. Then again, if you care about aesthetics and don't need it to bump, why not get Emotiva.
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Old 03-21-2013, 09:10 AM - Thread Starter
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Originally Posted by Jay1 View Post

Alright, a pair of dual driver subs is going to get you the most bang for your buck. Four of these RS10's is a hair over $500


What if that was scaled down just a bit to four 8" drivers? How much would I give up in terms of performance?

David
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Old 03-21-2013, 09:13 AM - Thread Starter
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Originally Posted by tential View Post

You could easily pump 700-800 watts into the sub

I would think that would probably be a bit of overkill for my purposes.

David
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Old 03-21-2013, 09:19 AM
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Originally Posted by crussader View Post

What if that was scaled down just a bit to four 8" drivers? How much would I give up in terms of performance?

Those 10"s I linked are really in a sweet spot performance wise as far as box size, low end extension, and sensitivity are concerned. You would give up a lot IMO.
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Old 03-21-2013, 09:39 AM - Thread Starter
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Originally Posted by Jay1 View Post

.. as far as box size, low end extension, and sensitivity are concerned. You would give up a lot IMO.

Can you quantify that a little bit? Can I get to 25hz with four 8s? Sensitivity greater than 86?

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Old 03-21-2013, 10:19 AM - Thread Starter
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Are there differences in the drivers used for automotive applications as opposed to home theater applications?

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Old 03-21-2013, 01:30 PM
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Quote:
Originally Posted by crussader View Post

Can you quantify that a little bit? Can I get to 25hz with four 8s? Sensitivity greater than 86?

Are you talking about four 8"s in a single box? The sealed box extension is going to be lacking from most 8" drivers, and if you do happen to find one with great extension it will require a very large cabinet, and likely not have enough xmax. I'm not aware of any that will do the job near as well as the 10s in a very reasonably sized box.

Car audio drivers can be used, but dont go off of any manufacturers guidelines for enclosure size (or sensitivity), as they are strictly talking about in car use, which is completely different from in room.
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Old 03-21-2013, 03:20 PM - Thread Starter
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Originally Posted by Jay1 View Post

Are you talking about four 8"s in a single box?

Two eights in a single box. Same configuration as you listed above, just in slightly smaller form factor.
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not aware of any that will do the job near as well as the 10s in a very reasonably sized box.

I really do understand that. I am just trying to quantify what the actual difference is.

David
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Old 03-21-2013, 05:03 PM
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The first problem is going to be finding suitable 8" drivers with an 8ohm impedance. Pick a driver you think would work and I can show you a comparison vs the 10s.
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Old 03-21-2013, 05:18 PM
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Why not go dual-opposed and cancel out vibrations? If you're going with 4 drivers, that makes the most sense to me. It's not like the dimensions change at all, and you get output reflecting off of different surfaces (walls, etc.) to potentially help even response just a little bit more.

I agree, though, 4x 10" in two sealed cabs is a great option when space is concerned.

Edit: also agree that a pro amp is the way to go. Assuming 4x 10" drivers spread across two sealed boxes, wire the two boxes for 4ohm loads, then use an EP4000 (with fan mod) to power them. That would be a killer setup using very little real estate!
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Old 03-21-2013, 06:18 PM - Thread Starter
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Originally Posted by Jay1 View Post

Pick a driver you think would work and I can show you a comparison vs the 10s.

I was thinking the 8" version of the driver you recommended. Would this be it ?

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-459

Put those in a box like you recommended except make it 2 inches narrower and 3 or 4 inches shorter.

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Old 03-21-2013, 06:42 PM
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Originally Posted by crussader View Post

I was thinking the 8" version of the driver you recommended. Would this be it ?

http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-459

Put those in a box like you recommended except make it 2 inches narrower and 3 or 4 inches shorter.

Those 8"s could go in a box even smaller then that, like 10" x 18" x 14", but here's what you're losing vs the 10"s. Both shown with 120 watts



Thats about 10hz difference in low frequency extension, and 3 db in output. You would also have the option to power the pair of 10s with much bigger amp like a Behringer EP4000 in the future without excursion issues if you wanted to maximize performance.

(sticking the sub in a corner will elevate the low end a lot more then you may think by just looking at the graph, but it is a sealed sub without boost)
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Old 03-21-2013, 06:50 PM
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Originally Posted by Jay1 View Post

Those 8"s could go in a box even smaller then that, like 10" x 18" x 14", but here's what you're losing vs the 10"s. Both shown with 120 watts



Thats about 10hz difference in low frequency extension, and 3 db in output. You would also have the option to power the pair of 10s with much bigger amp like a Behringer EP4000 in the future without excursion issues if you wanted to maximize performance.

(sticking the sub in a corner will elevate the low end a lot more then you may think by just looking at the graph, but it is a sealed sub without boost)

Just to reiterate what I said about going a pro amp like the Beringer(I chose the Crown XLS), you're just getting so much more power, for so much less money, in a smaller box, that is also lighter. Since it will most likely end up in a rack out of sight, why not get the most bang for buck?

Edit: Crown is much lighter less power, Behringer is a monster in terms of power and weight.... Could power a lot of subs with that thing.
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Old 03-21-2013, 07:09 PM - Thread Starter
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Thank you very much!

That graph is extremely helpful. I hate to trouble you further, but I wondering if could run a graph for just one driver in the cabinet so I can see what the two driver configuration brings to the table.

On another note, where does one buy a 12x24x16 cabinet? Does anyone make a pre-cut one, or do I build from scratch?

David
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Old 03-21-2013, 08:22 PM
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Originally Posted by crussader View Post

Thank you very much!

That graph is extremely helpful. I hate to trouble you further, but I wondering if could run a graph for just one driver in the cabinet so I can see what the two driver configuration brings to the table.

On another note, where does one buy a 12x24x16 cabinet? Does anyone make a pre-cut one, or do I build from scratch?

Here's a single RS265HF-4 (4 ohm 10" version) in a 12 x 14 x15 box, compared with the previous 2 subs. All with a 120 watts again.



Green = single rs265hf-4
Red = dual rs210ho-8
Blue = dual rs265hf-8
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Old 03-21-2013, 08:30 PM - Thread Starter
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Wow. One 10 beats two 8s. I didn't expect that. Really puts things into perspective.

David
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Old 03-21-2013, 08:34 PM - Thread Starter
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Assuming one doesn't go to extremes, does the shape of the box make a big difference, or is internal volume the most important factor?

David
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Old 03-21-2013, 08:43 PM
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Quote:
Originally Posted by crussader View Post

Assuming one doesn't go to extremes, does the shape of the box make a big difference, or is internal volume the most important factor?

No the shape isnt really important, just try to at least leave an inch or so of space behind the woofer to allow the vented motor room to breathe. If you go really long in one dimension it can lead to a pressure node, heavily stuffing the cabinet will help.
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Old 03-22-2013, 01:30 AM
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I'm just going to be completely blunt here....no offense just making a point that feel you should understand.

When talking about 30hz and down for sub duty dont even consider an 8" driver unless you want like 20 of them in spaces like media rooms or theaters. You will be extremely dissapointed to say the least.

I had a space issue on time in the living room and thought that if I bought the best commercial setup (paradigm) that fit the space I would atleast get a little of what I was looking for and it didnt even come close and it was the 10" cube. I even had an installer make a horn loaded enclosure for a JL8w6(?) for quite a bit of money for a GTR trying to save as much room as could and it didnt stay in there for more than 1 demo song. I wasted $400 on the enclosure and got credit on the driver towards my next one.

Point is 8" subs will not get you where you need to be in most cases even if you arent trying to rattle stuff on your walls.

I'd stick with the best 4 10"s you can afford right now and skip the amp until can save for a bigger one then just upgrade the amp. You'll have really clean bass for what space you'll be taking up if just design the enclosures to handle the amp that will upgrade to in the future. While your waiting on the upgrade amp one of your others will push them enough that they will sound way better than any 8" design you would have went with while also loafing along at 1/4 of the amount of power they can handle.

Going dual opposed would also help like someone said above. You'll be able to load them off of walls or furniture to help gain a few dbs all while keeping the cabs vibration free. Use the thickest wire you can get if they will be far from the amp too.

Try to choose a high xmax driver and model them in enclosures that will fit what amp you will be comfortable purchasing in the future. You dont build enclosures for the subs so to say, but rather match the enclosure to the amp you want to buy. And, since you're trying to save space that equals lots of power and small enclosure with high xmax drivers (most of the time).
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