Subwoofers - Konfused in Kelowna

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Wow

I am trying to learn about speaker building but am becoming a little overwhelmed! Okay, maybe a lot.

What I would like to do to get my feet wet is to build a subwoofer for my home theater/stereo system. I am reading (and reading) about this subject and am starting to understand SOME of the requirements. My issues revolve around sourcing suitable components (drivers/amps) before I can seriously start running numbers through the calculations. I must also admit that I am not 100% clear on how to interpret the results in order to ensure that I don't build a dud.

My strengths are with woodworking (and to a lesser extent, with electronics), obviously, my weakness is audio design. I am however persistent!

I noticed many Canadians on this site and am hoping that someone will be able to point me to a suitable local supplier (Okanagan, BC) and perhaps recommend a driver to get me started. I would also appreciate any/all advice on design and construction from anyone willing to share their knowledge.

In the meantime, I will go back to reading....

Thanks
 

GM

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Joined 2003
In a nutshell, for HT you ideally want a sub system that can effortlessly hit 115 dB peaks at the listening position with a BW to near DC (typically a multiple sub driver IB), so it's hard to have too big/powerful a sub system and why better for most folks to tell us about their room/HT layout and how big, expensive a sub system they can tolerate.

GM
 
so it's hard to have too big/powerful a sub system and why better for most folks to tell us about their room/HT layout and how big, expensive a sub system they can tolerate.

what are you trying to say?


Check out compound loaded subwoofers.
Go to the Solen website, they supply a speaker data base where you can roughly assess the frequency response for each driver in either closed box or vented box configuration, with the needed vent size.
They also supply all necessary thiele/small parametres for each driver they sell to calculate your won box.
They also supply you with some sample projects. Check out books published or distributed by audioxpress.

For clean subwoofer response, I also like to actively crossover with time alignment. The behringer dcx does a great job.

As per amps - check out some plate amps or some pro amps.
 
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GM said:
In a nutshell, for HT you ideally want a sub system that can effortlessly hit 115 dB peaks at the listening position with a BW to near DC (typically a multiple sub driver IB), so it's hard to have too big/powerful a sub system and why better for most folks to tell us about their room/HT layout and how big, expensive a sub system they can tolerate.

GM

Unless I misunderstand, what you are saying violates the ancient "400,000" rule (bottom freq X top freq should be 400,000). Allowing that it is an arbitrary rule of thumb and has no precision, but I believe systems sound lousy when they have too great a bass (inthe absence of great treble) or too great a treble (etc.).

I love profound bass and for sure the more the better but not without ensuring treble capacity.
 

GM

Member
Joined 2003
While I agree with you, the reality is that the widest BW movies have extremely low frequency BW and a DD reference limit of 20 kHz, so a large IB that when combined with room gain yields a ~flat BW to < 5 Hz is desirable for HT.

GM
 
Start with the limiting factor(s)...

The most important questions to ask yourself before starting any project are, "How much am I willing to spend and how much can I afford?". I always ask my clients those questions first. From custom autosound to custom PC builds, from kitchen renovating to building a garage, those same questions are first in every case.
There are many fine "budget" projects, and there is simply no limit to the other end of the spectrum. When building a sub, beyond expense, size is probably the next limiting factor(And don't forget the Wife). Beyond that is probably the "skill" level of the maker and the availablity of tools.
There is virtually no limit to driver selection, XOs or Power, so don't start there.
Let's Review
1.) $$$
2.) Size(Wife)
3.) Skills/Tools
4.) Let's design this sucker
5.) Breakout the wallet
6.) Let's build this sucker
7.) It's done=Bliss or disappointment
8.) Regardless of the outcome of "7", start drinking(If you have not already).
9. )Next!
 
GM said:


That it's a waste of time to suggest drivers, etc., until we know more about his performance goals and what limitations his room, budget, etc. impose.

GM


Thanks for the help so far. I am not sure of my actual performance goals and would likely be quite happy with almost any sub at this point. Having said that, I would rather "do it right" than simply make noise.

I am willing to accept (think I can sell to the boss) an enclosure of =< 3 cu.ft. If possible, I would like to build it 'down firing' but have heard that not all drivers are suitable for this application. My reasoning is that I have already built most of the cabinets in the room and would like to build the sub into a mathcing cabinet.

Obviously, like all things, budget is a concern, but considering that a mid-level sub in the local audio shops runs between $500-$1k, I am probably resigned to spending about the same. My room is approx 2000 cu. ft. and has hard surfaced floors and is opened at one end onto another room(I have no idea how you factor this into calculations, but there it is).

I have found Creative Audio and am looking at a couple of their "kits" with the idea that hands on is a good way to start learning. I was looking at the SD12 and a Bash-500. Perhaps, as pointed out above, I will take a closer look at the SDX15.

Anything else that I can add that will help? Any comments on the CSS OccamAudio kits?

Thanks
 
Re: Start with the limiting factor(s)...

discreteouts said:
The most important questions to ask yourself before starting any project are, "How much am I willing to spend and how much can I afford?". I always ask my clients those questions first. From custom autosound to custom PC builds, from kitchen renovating to building a garage, those same questions are first in every case.
There are many fine "budget" projects, and there is simply no limit to the other end of the spectrum. When building a sub, beyond expense, size is probably the next limiting factor(And don't forget the Wife). Beyond that is probably the "skill" level of the maker and the availablity of tools.
There is virtually no limit to driver selection, XOs or Power, so don't start there.
Let's Review
1.) $$$
2.) Size(Wife)
3.) Skills/Tools
4.) Let's design this sucker
5.) Breakout the wallet
6.) Let's build this sucker
7.) It's done=Bliss or disappointment
8.) Regardless of the outcome of "7", start drinking(If you have not already).
9. )Next!

Actually, I had the order something similar to:
1). wife (you want to do what?)
2.) drink
3.) $$$
4.) wife (it's going to cost what?)
5.) drink
6.) design (thank goodness for the internet and diyAudio!)
7.) build (can already build nice cabinets!)
7.a) drink
8.) Hope like hell it works as intended or....
9.) wife (how much did that end up costing?)
10.) even if it works, see number 9 above.
11.) drink

BTW, I may be optomistic in thinking that I can get away with a 3 cu. ft. cabinet. However, if I build it to look like a piece of furniture, perhaps I can sell it? I am thinking that bigger is better and 3 cu. ft. should be (more than?) big enough to make the stereo and video come to life?
 
Sub....terfuge..

If the floor beneath you is hollow(basement, crawl space), you can build an enclosure beneath the floor and open it to the room with a large floor register/grate(i.e. HVAC return grate). These come in all styles from wood to solid brass. The pictured one is rather small, but these can be had with an area suitable to a 15" woofer. If you hide the enclosure beneath the floor, you can make the box as big as required, heck, even 30 cu ft. if necessary.
An infinite baffe sub may also work well in this case.
Keep in mind that in some cases, a single point sub(one sub) may cause a serious "null" in a large room, specially if you cannot mount the opening just anywhere you please. In that case, two subs will usually correct the null(Null=Bass is strong over here, but weak over there).
The wife/boss should care much less about the size of the enclosure if she cannot even see it(when was the last time she entered the crawl space?).
BTW The floor joists themselves may create two sides of your enclosure, the floor the third, so you would only need to provide the fourth side and at least one end cap. Most floor joists are 16" on center(If I remember correctly), so you can start with that. Have fun!
 

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Mikey p said:
The closest to you would be Creative Sound Solutions in Abbotsford, B.C.
http://creativesound.ca/
The SDX15 ia an excellent sub. They also sell plate amps.

JRace said:
If you want a good localish sub, go with the SD from creative sound. Good price. They also have the amps you may need.

Yes, Bob is a good person to deal with. He has always been very accommodating with me. The SDX15 is a fairly new design and incorporates the XBL^2 motor system.
 
That Subduction 15" should be "adequate" for all but the criminally insane. So I'd get two.

Plate amps don't strike me as good value for money. Instead, cruise the pawn shops, classifieds, and eBay looking for used pro or home power amps. Maybe a new Behringer EP-2500, although prices seem to have gone up from what they were a couple years ago.
 
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Re: CSS SD12 Sub with baffle

jeff k said:
You can get the CSS SD12 12" subwoofer with an amp and a CNC baffle at www.occamaudio.com

That might make sense if Kelowna wasn't a short drive (~3 hr) from Bob's. Besides the Occam baffles are MDF. Seems a waste of energy to ship the driver to the USA from Abbotsford then back across the border to Kelowna.

Both the SD12 & the SDX15 simply use 2 pieces of 3/4" with an appropriate hole in them. The hole in the outer piece acts as the rebate.

Both of these are excellent, and even the 12" moves a lot of air (in my big room, a pair of SDX7 does a credible job).

I would recommend the sealed boxes -- the purpose of the vented boxes are for HT people that want a big bump at the bottom.

dave
 
dangus said:

Plate amps don't strike me as good value for money. Instead, cruise the pawn shops, classifieds, and eBay looking for used pro or home power amps. Maybe a new Behringer EP-2500, although prices seem to have gone up from what they were a couple years ago.

OK, so here's where I show my ignorance (again!). Assuming I find a suitable amp, do I simply hook it up as Sub Out from my HTAmp to a Line In on the Sub Amp? Then I would drive the Sub from the speaker out of the Sub Amp. My understanding is that the Sub Plate Amps take care of the frequency cross over.....I suppose I will have to take care of this myself if I follow the advice from DANGUS? ....and this means that I need to design/build/buy a suitable cross over for the sub? I am intrigued by the idea of using another component amp for the Sub, but will need to figure out exactly what this involves as the plate amp (or a dedicated sub amp) certainly seems easier.


:confused:
 
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APLJaK said:
OK, so here's where I show my ignorance (again!). Assuming I find a suitable amp, do I simply hook it up as Sub Out from my HTAmp to a Line In on the Sub Amp? Then I would drive the Sub from the speaker out of the Sub Amp. My understanding is that the Sub Plate Amps take care of the frequency cross over.....I suppose I will have to take care of this myself if I follow the advice from DANGUS? ....and this means that I need to design/build/buy a suitable cross over for the sub? I am intrigued by the idea of using another component amp for the Sub, but will need to figure out exactly what this involves as the plate amp (or a dedicated sub amp) certainly seems easier.

A modern HT amplifier will have a subwoofer out which has a low pass (cross-over) function applied to that. In addition the plate amp will have its own crossover. So you actually have 2 XOs (for this situation you just turn the plate amp XO all the way up -- some may allow you to defeat the XO.

dave
 
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