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-   -   10" cabinet transformation? (http://www.diyaudio.com/forums/subwoofers/227192-10-cabinet-transformation.html)

Rullknufs 7th January 2013 12:28 AM

10" cabinet transformation?
 
Hello!

I currently have a pair of 10" subwoofers, cabinets are ~45l sealed.
The driver is a noname el cheapo I got from a sale. They play pretty nice but I'd like some more action below ~45Hz which is where they stop now. I was thinking to maximize performance 30Hz and up. I have a massive room peak at ~50-55Hz so I will EQ them down 7-10dB there if it matters. They will be crossed over at 60-80Hz or something to a pair of floorstanders with two Morel CAW638 per cabinet.

This is the T/S parameters I've got from the datasheet
http://i.imgur.com/MYSM1.png
But maybe it's better to re-measure them? How can I find out how to do that? I have a multimeter (cheap one but have access to better ones).

Impedance chart shows this
http://i.imgur.com/Ubwxt.png

I was thinking to either add a port to my current cabinets or build new, bigger cabinets (of birchply instead of particle board) and include a port.

Questions are, what would you recommend me to do? Would this driver fit in any type of horn, transmissionline or such or is vented the thing to aim for? What cabinet size/tuning do you recommend? WinISD says that ~70l tuned to ~25Hz is ok.

Edit: This it how the driver looks like
http://i.imgur.com/IHwBs.png

Inductor 7th January 2013 01:44 AM

The EBP recommendation is sealed (42).
It should complement the pour bass extension of the Morels (good for Quarter wave).
Quote:

I have a massive room peak at ~50-55Hz so I will EQ them down 7-10dB there if it matters.
Try a bigger box then. Make Qt=<0.8
Quote:

cabinets are ~45l sealed

Rullknufs 7th January 2013 08:31 AM

A bigger sealed box doesn't give me anything at all really.

http://i.imgur.com/VCRzZ.png

chris661 7th January 2013 09:54 AM

A bigger sealed box will give you more low bass and less energy in the 60-80Hz range, but maxSPL (as shown in the graph) remains constant, as its simply a function of frequency, Xmax and Sd.

Have you tried playing with Linkwitz Transforms?
You'll be able to get a response that's more to your taste, but if you're running out of excursion now anyway, you're going to need to go ported/TH/T-TQWT or something.


Looking at the midbass you're crossing over to, you might be better off giving the midbass some more cabinet space, and think about doing away with the subs altogether: the Morel drivers are of much higher quality (so the question there is quality or quantity of bass?).


Chris

Rullknufs 7th January 2013 10:03 AM

Haven't played very much with linkwitz transform, but modeled with it once and I ran out of excursion very quickly that way. The midbass cabinets will stay as they are, they are in a ~51l (if I remember correctly) cabinet that is kind of aperiodic. It has a slot port but it has quite a bit of damping material in it. They reach down to 30Hz well but not loud at all and I run out of excursion on the Morels quickly at ~40Hz.

So what I need is quantity, mostly like 50Hz and below. Above 50Hz the Morels are fine, at 50Hz anything is fine because of my room gain but at like 40Hz and below I want some more grunt.

Inductor 7th January 2013 11:15 PM

People make such an effort to get low extension from poor woofers that are made and better for car audio that have more gain in that frequency band, inside the car. I don't know why people make such an effort to make a bad audio system. The tactics are so wrong. First, it doesn't work, then add subwoofers, then they go active, you name it, plus complicated Linkwitz Transforms and such, when everything people need it's bass extension from their main stereo system. (If this is your case) All I would do, trash the woofers and build from a new set of good woofers with the new T/S parameters required and better quality. You can just post the new requirements, and it's easy to fix.
If what you want it's expressed in this thread, as many others DIY posters, then stay cool.:cool:

GM 8th January 2013 06:58 AM

Quote:

Originally Posted by Rullknufs (Post 3314095)
I was thinking to either add a port to my current cabinets or build new, bigger cabinets (of birchply instead of particle board) and include a port.

Questions are, what would you recommend me to do? Would this driver fit in any type of horn, transmissionline or such or is vented the thing to aim for? What cabinet size/tuning do you recommend? WinISD says that ~70l tuned to ~25Hz is ok.

Hmm, I thought these specs looked familiar. There's lots of good info with some good, low tuned designs, so why the new thread? Makes me feel like I have already wasted too much time on you.

http://www.diyaudio.com/forums/subwo...hose-subs.html

GM

Rullknufs 8th January 2013 07:47 AM

Quote:

Originally Posted by Inductor (Post 3315609)
People make such an effort to get low extension from poor woofers that are made and better for car audio that have more gain in that frequency band, inside the car. I don't know why people make such an effort to make a bad audio system. The tactics are so wrong. First, it doesn't work, then add subwoofers, then they go active, you name it, plus complicated Linkwitz Transforms and such, when everything people need it's bass extension from their main stereo system. (If this is your case) All I would do, trash the woofers and build from a new set of good woofers with the new T/S parameters required and better quality. You can just post the new requirements, and it's easy to fix.
If what you want it's expressed in this thread, as many others DIY posters, then stay cool.:cool:

Yes, but at $30 per woofer it was a good deal. I know I should build better woofers but I want to try how far I can get with these first. Remember I'm still a high school teenager and I recently spent a little more than $1700 on my main speakers, that's more money than I earn in a year! A pair of good subwoofers including new amplifier would cost me at least another $1000 or maybe even more. But improving my current subwoofers would cost me less than ~$100-150. I have many other things I'd wish to spend money on, car, parties, traveling, gym stuff and so on.


Quote:

Originally Posted by GM (Post 3316017)
Hmm, I thought these specs looked familiar. There's lots of good info with some good, low tuned designs, so why the new thread? Makes me feel like I have already wasted too much time on you.

http://www.diyaudio.com/forums/subwo...hose-subs.html

GM

What do I need? A way to achieve good SPL down to ~30Hz while still keeping it as cheap as possible. You adults who have jobs may think that $1000 isn't very much, if you want you could get that much spare money in a month without problems. For me it would take almost a year, see the difference? Yes, If I could I would just go buy a pair of Scan-Speak 32W/4878T00 and be happy but that would require me to save money for one and a half year and not buy anything else during that period.

But if you guys are so pessmistic I'll just go with what WinISD says and see what happens. Might not be the best but it should get me closer to my goals.

Moonfly 8th January 2013 12:43 PM

Quote:

Originally Posted by Rullknufs (Post 3314512)
Haven't played very much with linkwitz transform, but modeled with it once and I ran out of excursion very quickly that way.

Chances are you modelled incorrectly for the addition of the circuit. If you add in a LTC, then you need to reduce the signal power used. Look at the amplifier apparent load graphs, and reduce the main signal input until the maximum power simulated in the apparent power graph matches you original max input signal. So, if you used 500 watts input power, then added in a LTC, you then need to modify the input signal so your apparent power graph maxes out at 500 watts. Reducing input power to 10% is usaully a good place to start.

What you will notice is that your original response shape changes, but if your target frequency was say 15hz, you get pretty much the same spl at that frequency (because thats the limits of the system), but everything above it is flattened out.

Something else you will then notice is how cone excursion and group delay are reduced in the upper range (thus improving the upper bass character of the sub), and all the high excursion and increased GD will have been pushed lower down the FR. If your using a large driver (15" or more, or multiples of smaller drivers), then a 10hz target with a .707 or less target system Q will give the best result. With a 10hz target, all the cone excursion and GD above 20hz is reduced dramatically. These properties below 20hz will increase above and beyond what the maximums were in the un-eq'd response, but this isnt very important because its all pushed below the 20hz threshold where your ears simply wont pick up on them due the frequency being too low.

Inductor 8th January 2013 01:24 PM

Quote:

Originally Posted by Rullknufs (Post 3316058)
Yes, but at $30 per woofer it was a good deal. I know I should build better woofers but I want to try how far I can get with these first. Remember I'm still a high school teenager and I recently spent a little more than $1700 on my main speakers, that's more money than I earn in a year! A pair of good subwoofers including new amplifier would cost me at least another $1000 or maybe even more. But improving my current subwoofers would cost me less than ~$100-150. I have many other things I'd wish to spend money on, car, parties, traveling, gym stuff and so on.

Hi, and thanks for explaining, I now understand. Not a easy way out. Take your time.:D
Edit: I like your main speakers. Your problem must be just new subs.
http://www.diyaudio.com/forums/subwo...ml#post3006227
Some car guy will buy that (subs) from you. Just embark in a new project. Post with question for the best suitable sub for you with set-up you already have and cost you want to achieve. Components and amps are also expensive I have to agree. (More) In this case simple is better. Be appreciative of others spent time with your thread and they will help.
I might be wrong but it seems you are doing it fine... "12dB boost at ~25-30Hz to extend the bass a little further" (you said and seem pretty happy) so what's exactly that you need?


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