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Rate my Subwoofer Design

Wharfedale Speakers

keith_correa

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Jan 17, 2009
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Location
Mumbai
Short answer: if the OP is building with the driver he simmed and he's OK with the box size, he should build it vented for low extension.
 

yellowcurrypaco

New Member
Joined
Mar 11, 2020
Messages
17
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Location
Delhi
I can go lower & louder with a single 12inch iwai in ported with lower power requirement.
105db at 20hz
Single iwai 12inch
75L
250W

And
105db at 18hz
Dual 12inch Iwai
150L
500W

considering boundary and room gain, one will get more SPL a lot more infact.

And when you apply eq your power requirements are not flat at 400W , the eqed frequency needs a lot more power more like 800W..


Regards
Aniket
Mumbai
Do you have the .wdr file for the Iwai driver. I tried to manually input the values but when I try to design it winisd, its having some problems.

Pls see the excellent app note from Peerless http://www.tymphany.com/wordpress/wp-content/uploads/2018/10/Appnote-xlssub12inch.pdf

A ported can take a lot of load off the driver around the tuning frequency, it translates into clean sound. A sealed is fine too and easiest to build but needs one driver size bigger as compared to ported. So what 10" ported can do, a 12" selaed will be needed to match it. Ported gets a bad name coz it couples to a room mode and excites it, but if one tunes a ported very low like 20Hz or so then its not a problem at all. Typical rooms will not have any mode down that low.

Prateek has a very big size driver where a 'sealed vs ported' really does not matter. In home listening situation the pro grade driver will just loaf around.

Get 2, 12" drivers, put them on opposite sides of the cabinet, now port to very low freq. Eq in the room. Have enough amp power. You'll have a very fine system. Car drivers do perform very well in small cabinets.
Also, a good sub will do justice to both HT as well as music.
Thanks for that, should be fun to read!
Have you heard anything about the Iwai drivers and if they're comparable to other well known brands?

Short answer: if the OP is building with the driver he simmed and he's OK with the box size, he should build it vented for low extension.
Yeah I'm okay with it but the small volume and ease of construction of the sealed sub is giving me a dilemma.
 

prateekatasniya

Well-Known Member
Joined
Oct 27, 2016
Messages
1,005
Points
83
Location
Hyderabad
I can go lower & louder with a single 12inch iwai in ported with lower power requirement.
105db at 20hz
Single iwai 12inch
75L
250W

And
105db at 18hz
Dual 12inch Iwai
150L
500W

considering boundary and room gain, one will get more SPL a lot more infact.

And when you apply eq your power requirements are not flat at 400W , the eqed frequency needs a lot more power more like 800W..


Regards
Aniket
Mumbai
The single driver ported is a real good option for big room and small budget.

However for smaller rooms and relatively higher budget sealed is anytime better..
And that 400 watts I mentioned is for 25hz.
 

adas

Member
Joined
Mar 17, 2017
Messages
50
Points
18
Location
mumbai
The single driver ported is a real good option for big room and small budget.

However for smaller rooms and relatively higher budget sealed is anytime better..
And that 400 watts I mentioned is for 25hz.
What would the power requirements be say at 10hz or 80hz ?
 

kapvin

Well-Known Member
Joined
Jul 23, 2009
Messages
1,082
Points
83
Location
Mumbai/ Thane
A friend of mine gave me the parameters of a subwoofer driver without telling me the name/model and this is what I came up with.

Volume: 50 L
Tune Freq: 23 Hz
The port is a rectangular port which is to be folded.
Port Dimension (cm): 20(W) X 4(D) X 83(L)

Filter:
Lowpass (Butterworth n=4, fc=80Hz)

System Input Power = 250W

Graphs:
1. Transfer Magnitude Function
View attachment 44839
2. SPL
View attachment 44840
3. Rear Port Velocity
View attachment 44841
4. Rear Port Gain
View attachment 44842
5. Impedance
View attachment 44843
6. Impedance Phase
View attachment 44844
7. Cone Excursion
View attachment 44845
8. Group Delay
View attachment 44846

Do you see anything that is not good, any issue? Any more information you need/want?
I assume he gave you SD and other stuff.

couple of observations

1. to deliver this kind of tuning into a 50L box, either the woofer is hugely inefficient or a driver with very high motor force (So not cheap), or maybe both. Its also likely not to be a 12" woofer, good 10" woofers model this way. Am very curious as to which model if its 12", pray share.

2. the 83 cm port is way too long. you will definitely have port resonance at about 200hz or maybe below and it will honk like crazy. And such a narrow slot is likely increase port resistance and reduce effectiveness of the port (but also reduce the honk). With such tuning parameters, a passive radiator is almost always a better idea.

Edit: chart 7 shows excursion of 9mm at 30hz with 250w (as per your specs).. so not very efficient at all.. is the xmaxx really 15mm? that at 23hz tuning at 50litres makes it one of those mega magnet 12" (if it is 12") and definitely redlining your budget. youve got me very curious now.
 
Last edited:

yellowcurrypaco

New Member
Joined
Mar 11, 2020
Messages
17
Points
3
Location
Delhi
I assume he gave you SD and other stuff.

couple of observations

1. to deliver this kind of tuning into a 50L box, either the woofer is hugely inefficient or a driver with very high motor force (So not cheap), or maybe both. Its also likely not to be a 12" woofer, good 10" woofers model this way. Am very curious as to which model if its 12", pray share.

2. the 83 cm port is way too long. you will definitely have port resonance at about 200hz or maybe below and it will honk like crazy. And such a narrow slot is likely increase port resistance and reduce effectiveness of the port (but also reduce the honk). With such tuning parameters, a passive radiator is almost always a better idea.

Edit: chart 7 shows excursion of 9mm at 30hz with 250w (as per your specs).. so not very efficient at all.. is the xmaxx really 15mm? that at 23hz tuning at 50litres makes it one of those mega magnet 12" (if it is 12") and definitely redlining your budget. youve got me very curious now.
1. It is 12" and has a sensitivity of about 84dB I think. I'll let you know when I get to know the exact model.

2. Yeah this driver requires a very long port so I have to fold it once in this design. 1st port resonance shouldn't be problem I think since the simulated port resonance is 206.77 Hz and with a high pass filter, this sub will barely just cross 200 Hz. Passive would be nice but the added cost is a problem.

3. Yes Xmax really is 15mm. This is one of the reasons why I like this driver even though the volume is big.
 
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