The Bargain Hunter's subwoofer ...

[mpw]

I'll send you the bill. hyeah:

i knew it

which is why i offered :cheers: and not the bill for a drink :lol:

rgds

 

[keith_correa]

I'll give you a free tip which could earn me more beer:

Look up Basotect. They are sold retail under different brand names - Mr. Clean etc. Considering what they can do, they are inexpensive. Line the inner walls with these. Then stuff the box. If you use these, you can get away with using 0.75" thick walls too.

My sister works for BASF and she has used this for soundproofing her kids rooms. She vouches that they work very well. She can buy them very cheap (practically free) direct from BASF and I've requested her to bring a lot for me when she visits us next. I'm waiting eagerly!!!

 

[quad]

Google shows up generic Indian (Mumbai) made melamine acoustic foam.
These may be cheaper, but not sure if BASF has some proprietary/patented
magic in the Basotec.

My sister works for BASF and she has used this for soundproofing her kids rooms. She vouches that they work very well. She can buy them very cheap (practically free) direct from BASF and I've requested her to bring a lot for me when she visits us next. I'm waiting eagerly!!!

 

[Hari Iyer]

Won't addressing room modes and applying golden ratio to speaker placements be somewhat better, easier, aesthetically pleasing and cheaper option?

 

[mpw]

Hari bhai

Let's get the woofer done and then we look at what's next.

One step at a time..

Rgds

 

[keith_correa]

Hari bhai

Let's get the woofer done and then we look at what's next.

One step at a time..

Rgds

I think he's talking about NOT building the sub and doing what he suggests instead. No?

OK, one more suggestion: Apply craft foam to the inner walls. They are easily available at all stationery shops. Will mass load, damp yada yada. Account for the volume taken by them too since they are closed cell foam.

 

[Hari Iyer]

I think he's talking about NOT building the sub and doing what he suggests instead. No?

Not really, i am suggesting to build the sub and look at treatment options far later. You never place the speakers considering the treatment options. In fact treatment should be considered at the end after everything else fail,because they are not very easy to implement, difficult to simulate, Buy and install. Also the results could be very subjective.

 

[mpw]

After validating an internal volume requirement of 30 liters, my total cabinet Outer dimensions will be as under :-

30 Liters cabinet internal volume
+
volume of the driver itself = 5.90 liters ( volume of cylinder approximation )
+
volume of MDF ( 5 sides each side 1 inch by 16 inch by 16 inch ) = 5 x 4.19 = 20.95 Liters
+ volume of MDF ( 1.5 inch thick front baffle ) = 1.5 inch*16 inch*16 inch = 6.30 liters
+ volume of sealed cabiner on the rear of the subwoofer for the Hypex DS 4.0 = 285 mm * 285 mm * 100 mm = 8.15 liters

So our total cabinet volume works to = 30+5.9+20.95+6.3+8.15 = 71.30 Liters ( OUTER DIMENSIONS ) = 4350 cubic inches

Therefore, for decor sake if i take a 15 inch width and a 15 inch height, then the depth will be = ((4350/ ( 15 * 15 )) = 19.33 inches approx ( including the 4 inches for the Hypex DS 4.0 )

Alternately, if i were to take 16 inches width and 16 inches height, then the depth would be = 4350/256 = 16.99 inches = 17 inches ( including the 4 inches width at the back for the Hypex DS 4.0 )

The latter option would look better i guess.

Any thoughts on the calculations ?

I am not adding anything for damping material as i think i will go with a layer of tar sheet or acoustic foam and also polyfill on the insides.


regards
mpw

 

[Hari Iyer]

Cubes are not considered good for sound. Try golden ratio if the volume and size allows, there will be fewer standing waves to tackle later internally. Exact cubes suffer from standing waves issues.

 

[mpw]

plan to use good bracing and damping.

Golden ratio, i fear, leads me to obtuse figures which wont suit my decor.

regards

 

[keith_correa]

For a stuffed box, I doubt that standing waves will be an issue. Bracing and damping will play a bigger role than standing waves.

mpw, what sort of bracing are you thinking about implementing?

Edit: with bracing, depending on the type of bracing structure, you can implement it in a golden ratio

 

[mpw]

keith,

the bracing part will discuss with the person who is making the cabinet. There are many images of bracing for subwoofer cabinet on google baba.

by today we hope to complete the drawing.

also will give a thought to the type of joint - maybe batten type....

I suppose i would have to order the tar / foam sheets if i plan to use them on the inside walls immediately after MDF cutting.


regards
mpw

 

[captrajesh]

Even if i were to buy that kit ( which i will not ), i am afraid i would have to go thru the same thing = to buying a good driver and a good plate amp separately and figuring out the cabinets etc.

Not really the same thing. You don't need to figure out what the box dimensions would be et al. The vendor, GR Research is providing you the exact dimensions. All you have to do is cut the MDF sheets and fix them.

i think it better to go thru this learning curve than sit on the sidelines passing comments on "subwoofer integration".

Designing a subwoofer from ground up and subwoofer integration are two different things. One doesn't need to design a subwoofer to figure out how to integrate a subwoofer. Don't understand your POV.

Lastly - what is a proven design captain ??

I'm sure you understand what a proven design is.

The design maybe proven but the workability for me / you in our rooms is not.

That's precisely why you should exercise an available option of playing the already existing subwoofer in your set up rather than building something grounds up and later realising that it doesn't work for your room.

Tell me, how would you know that the one you are trying to build would work in your room?

 

[mpw]

Not really the same thing. You don't need to figure out what the box dimensions would be et al. The vendor, GR Research is providing you the exact dimensions. All you have to do is cut the MDF sheets and fix them.


Designing a subwoofer from ground up and subwoofer integration are two different things. One doesn't need to design a subwoofer to figure out how to integrate a subwoofer. Don't understand your POV.


I'm sure you understand what a proven design is.


That's precisely why you should exercise an available option of playing the already existing subwoofer in your set up rather than building something grounds up and later realising that it doesn't work for your room.

Tell me, how would you know that the one you are trying to build would work in your room?

Captain,

i think you mean well....but..

i have passed thru this make vs kit vs buy debate and i am going it this way only. As mentioned in the thread the driver and the amp are here already.

I have no intention to buy even in a kit form as i think i can get it done at a better cost with all due respect to GR research / Rythmik etc..

I have a feeling it will be a better or atleast = sound wise.

Request you to please not focus on what has already passed and see if you can use your experience to help me with a few things i asked for.

Rgds
mpw

 

[captrajesh]

As mentioned in the thread the driver and the amp are here already.

Oh good lord! I seem to have missed it. That was fast!

I have no intention to buy even in a kit form as i think i can get it done at a better cost with all due respect to GR research / Rythmik etc..

I sincerely wish and hope that you would succeed.

 

[mpw]

captain,

Dayton RSS26510 HF ( 4 ohm ) 10 inch driver + Hypex DS 4.0 plate amp

Dayton is from diyaudiocart

Hypex from Hypex Electronics B.V. Webshop

last night, made a sketch of the cabinet drawing and gave it for cabinetry.

the overall outside dimensions are 16 inch by 16 inch by 21 inch deep ( incl 4 inches sealed enclosure within this cabinet for Hypex DS 4.0 plate amp )

Bracing - was decided on and the cabinet will have 1 strong brace inside. Maybe 2 if we are not satisfied.

Jointing - the MDF - will be done by suitably as well with a joint to ensure a heavy & tight cabinet.

The cabinet might take longer if i travel on work as i have told my friend i want to be at his workshop when the assy tales place. and that means only weekends available.

hope to get some bitumen sheets, felt sheets and foam to do some internal damping.

I want to do a piano black finish and i will have to take the cabinet to an auto garage to get it done but all that is very far away at the moment.

waiting is hard ..

)

mpw

 

[Hari Iyer]

Good to know developments, btw what is the speaker system Q for this dimension?

 

[mpw]

Will hear and find out

)

 

[Fantastic]

The damping is only used for a sub if required. The simple explanation is that it makes the cabinet volume appear bigger ...up to a point. So the overall Q of the speaker can be adjusted a bit by this if it turns out to be a bit smaller than it should be. This only affects the bass signals. Your sub , hopefully, is rolled off above 100Hz at ( at least ) 24dB/octave . You don't want any low frequency male vocals to come out of it.

I measured the system Q of my Lab12 in a 39 cm cube again last night.
Qtc is 0.67 and the resonant frequency is 43.5 Hz. No box damping required as it is already below the nominal Q of 0.707 . The good thing about a lower Q is that usually it works very well with close wall placement without having a hump in the response. Of course that is also room dependent. I'll be measuring that soon. Unfortunately the room is crowded with a lot of things. But some measurement is better than nothing. I can also compare room center with near wall placement. I'm going to measure it at the listening level rather than 2 m away on the floor.

 

[mpw]

Your sub , hopefully, is rolled off below 100Hz at ( at least ) 24dB/octave . You don't want any low frequency male vocals to come out of it.

while i do not exactly understand how this roll off happens, the Hypex plate amp will be set at about 50 Hz - 55 Hz and they do mention something like an 18 dB roll off in the instruction manual.

i did check with a few folks and i understand this is a nice plate amp and i left it at that.

TECHNICAL DATA:
Continuous output power (8 Ohm): 210 Watts (+0, -0.5dB)
Continuous output power (4 Ohm): 400 Watts (+0, -0.5dB)
Subsonic-filter: 12Hz / -3dB, 24dB/Octave
Phase: 0 - 180, 180 - 360
Crossover frequency subwoofer: 30Hz - 120Hz, 18dB/Octave
Bassboost: 20Hz - 50Hz
Bassboost level: 0dB - +6dB
Damping factor: 1000
Protection: Output shortcut / DC-error
Crossover filtering: Linkwitz-Riley, 18dB/Octave
Input impedance RCA: 10kOhm
Input impedance high level: 1kOhm
230/115Vac switchable

MECHANICAL DATA:
Dimensions: 267mm x 267mm x 70mm (W x H x D)
Weight: 4.1Kg


If some bleating does come out of the sub :lol: .... well... we will figure it out..

i guess... i will know how the pudding tastes.... ... once its ready for trials.


PS1 : I am aware i may not be technically as proficient as many of you are but i am going by best available knowledge to me and ofcourse my instinct.

PS2 : I apologize if some of my questions or understanding of technicalities are a trifle under cooked.

regards
mpw