I need your advice on this diy sub.

Riaad · 29th August 2003, 06:39 AM

Hi

I have ordered a Sub kit locally. Its the only one I could find.I am new to the Diy scene and need help.
It Kit includes:

12"
1x 4inch port - 100mm
Fs 22Hz
Vas 120L
Qts 0.50
RMS 250W
Xmax 8mm(one way)
100W Amplifier

Output 70W RMS at 1% distortion
100W Max at 10% distortion
Load 4 - 8 ohm

Both amplifiers are panel mount with an electronic crossover. The features are as follows:

Volume control
Phase switch
Variable cut off frequency
High and low level inputs

According to Winisd, its more suited to a sealed box but I tried both vented and sealed .

Sealed :
Volume:4.439 ft^3
Qtc: 0.7
FC: 31.16Hz

Vented
Volume: 5ft^3
Tuned to 20hz
4inch port
Port length:13.67

Do these look right?. I would prefer a smaller box but these seem to give the smoothest response.Which Box should I go for .It will be used mostly for home theater, say 80 HT - 20 Music.
Can you also maybe suggest any other configs?.

My room is not big - 10ft x 12ft.

Riaad

AndersP · 29th August 2003, 10:13 AM

Sealed by all means.

I would suggest a bigger box though, to get Qtc closer to 0.6. Stuff it good ( loose but full ) with mineral wool. Big pieces doesn´t tend to get inside the motor assembly.

Don´t use a vented alignment with that 12".

Are you building 1 or 2 subs? You say you have two amps, but I don´t understand how many drivers you have?

Riaad · 29th August 2003, 03:56 PM

What response can I expect from a sealed design taking into account room gain?.

I am just building one , sorry my mistake i just have 1 amp.

Why do you suggest I dont go vented .Any particular reason?.

Thanks

Riaad

mikee12345 · 30th August 2003, 11:06 AM

Qts is high for a ported box

120L and 22hz tuning+ peaky midbass,but perhaps you would like that extra boost
<using isd online i dont have winisd on this pc>

room gain- perhaps 6db at 20hz ?

it really depends.

rossco · 30th August 2003, 11:21 PM

Go ported.........Qts is fine if you get your calculations right

Riaad · 1st September 2003, 07:21 AM

Is the port length ok? 13.82 inches.

The kit only contains 1 x 100mm port. I would have to get a longer port then. will normal 4inch PVC pipe be ok?.

Also can I just connect the port so thats it flush with the surface of the box or should I router the the side of the hole?.(flared ).

Thanks
Riaad

29th August 2003, 06:39 AM	#1
Riaad diyAudio Member Join Date: Aug 2003 Location: Johannesburg	I need your advice on this diy sub. Hi I have ordered a Sub kit locally. Its the only one I could find.I am new to the Diy scene and need help. It Kit includes: 12" 1x 4inch port - 100mm Fs 22Hz Vas 120L Qts 0.50 RMS 250W Xmax 8mm(one way) 100W Amplifier Output 70W RMS at 1% distortion 100W Max at 10% distortion Load 4 - 8 ohm Both amplifiers are panel mount with an electronic crossover. The features are as follows: Volume control Phase switch Variable cut off frequency High and low level inputs According to Winisd, its more suited to a sealed box but I tried both vented and sealed . Sealed : Volume:4.439 ft^3 Qtc: 0.7 FC: 31.16Hz Vented Volume: 5ft^3 Tuned to 20hz 4inch port Port length:13.67 Do these look right?. I would prefer a smaller box but these seem to give the smoothest response.Which Box should I go for .It will be used mostly for home theater, say 80 HT - 20 Music. Can you also maybe suggest any other configs?. My room is not big - 10ft x 12ft. Riaad

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29th August 2003, 10:13 AM	#2
AndersP diyAudio Member Join Date: Aug 2002 Location: Middle Sweden	Sealed by all means. I would suggest a bigger box though, to get Qtc closer to 0.6. Stuff it good ( loose but full ) with mineral wool. Big pieces doesn´t tend to get inside the motor assembly. Don´t use a vented alignment with that 12". Are you building 1 or 2 subs? You say you have two amps, but I don´t understand how many drivers you have?

29th August 2003, 03:56 PM	#3
Riaad diyAudio Member Join Date: Aug 2003 Location: Johannesburg	What response can I expect from a sealed design taking into account room gain?. I am just building one , sorry my mistake i just have 1 amp. Why do you suggest I dont go vented .Any particular reason?. Thanks Riaad

30th August 2003, 11:06 AM	#4
mikee12345 diyAudio Member Join Date: Nov 2002 Location: NZ	Qts is high for a ported box 120L and 22hz tuning+ peaky midbass,but perhaps you would like that extra boost <using isd online i dont have winisd on this pc> room gain- perhaps 6db at 20hz ? it really depends.

30th August 2003, 11:21 PM	#5
rossco diyAudio Member Join Date: Jul 2003 Location: UK	Go ported.........Qts is fine if you get your calculations right

1st September 2003, 07:21 AM	#6
Riaad diyAudio Member Join Date: Aug 2003 Location: Johannesburg	Is the port length ok? 13.82 inches. The kit only contains 1 x 100mm port. I would have to get a longer port then. will normal 4inch PVC pipe be ok?. Also can I just connect the port so thats it flush with the surface of the box or should I router the the side of the hole?.(flared ). Thanks Riaad

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