Rate my Subwoofer Design

[yellowcurrypaco]

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

2. SPL

3. Rear Port Velocity

4. Rear Port Gain

5. Impedance

6. Impedance Phase

7. Cone Excursion

8. Group Delay


Do you see anything that is not good, any issue? Any more information you need/want?

 

[prateekatasniya]

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?

Go for ported only if your room is huge or if you need really high SPL.

Go for ported only if your room is huge or if you need really high SPL.

What's your room size btw ??

 

[yellowcurrypaco]

What's your room size btw ??

13 x 16 x 8.5
I do plan to go with a ported sub. What would you consider this room size to be, small, medium, large?

 

[prateekatasniya]

13 x 16 x 8.5
I do plan to go with a ported sub. What would you consider this room size to be, small, medium, large?

It's small..
And with your budget you can easily make a powerful enough sealed subwoofer.

 

[mpw]

13 x 16 x 8.5
I do plan to go with a ported sub. What would you consider this room size to be, small, medium, large?

What's the driver size of the simulation ?

13 x 16 x 8.5
I do plan to go with a ported sub. What would you consider this room size to be, small, medium, large?

Your room size is S/M.

A 10 inch should do you fine either case IMO

If your application is mainly movies..then ported

If mainly music..then sealed...it's simpler I think.

What's the rest of the setup like ?

 

[prateekatasniya]

Your room size is S/M.

A 10 inch should do you fine either case IMO

If your application is mainly movies..then ported

If mainly music..then sealed...it's simpler I think.

What's the rest of the setup like ?

For any given scenario sealed is better if it can pump sufficient SPL. Movies or music it doesn't matter.
for his budget and room size he can get sufficient SPL from a sealed subwoofer.

However if he wishes to buy a branded sub.. I would surely recommend a ported sub in that budget for movies.

 

[yellowcurrypaco]

For any given scenario sealed is better if it can pump sufficient SPL. Movies or music it doesn't matter.
for his budget and room size he can get sufficient SPL from a sealed subwoofer.

However if he wishes to buy a branded sub.. I would surely recommend a ported sub in that budget for movies.

Do you think this sealed design will be good for a room of 13X16X8.5?
It has a boost of 4db at 30Hz. They are of 2 different volumes, with everything else the same.
Or should I still go for the ported one which can go much lower?

What's the driver size of the simulation ?

The driver is 12".
Also, please see my reply above.
Gave away my previous system so, I don't have anything right now!

 

[prateekatasniya]

Do you think this sealed design will be good for a room of 13X16X8.5?
It has a boost of 4db at 30Hz. They are of 2 different volumes, with everything else the same.
Or should I still go for the ported one which can go much lower?
View attachment 44855

Is it a closed room or open room ( like a living room) ?
Sealed can go much lower and cleaner.

 

[adas]

Is it a closed room or open room ( like a living room) ?
Sealed can go much lower and cleaner.

Incorrect , sealed maybe cleaner but definitely not lower .

 

[prateekatasniya]

Incorrect , sealed maybe cleaner but definitely not lower .

Sealed goes lower.. but more power is needed to produce higher SPL.
Sealed subs can play under 10hz..
Very very few ported subs can match that.
Jtr being one of them..

( my custom 18" sealed subwoofer can produce 105db at 9hz in room)

 

[keith_correa]

Sealed can go much lower and cleaner.

As compared to what?

"Clean" is subjective.

In the sims that are posted where do you see the sealed sim going lower than the vented sim?

Everything depends upon the driver and it's parameters. Like the Shakira song goes - "Sims don't lie"!

 

[adas]

Sealed goes lower.. but more power is needed to produce higher SPL.
Sealed subs can play under 10hz..
Very very few ported subs can match that.
Jtr being one of them..

( my custom 18" sealed subwoofer can produce 105db at 9hz in room)

Incorrect again , it's no where written that a sealed sub can play below 10hz and a ported can't. There is unloading below tuning frequency in ported sub but there are ways of mitigating that. It all depends on the SPL required and at what frequency. Sealed gives better transient response but can never go as low as ported , if you do use eq to makeup the lost lower frequency in sealed you run the risk of power compression and exceeding xmax.
Speaker design is a trade-off between achievable parameters , can't have it all.
Its good that your sub reaches 105db SPL at 9hz but that's with room gain , using a 18inch prodrivers is not always feasible in homes.
Using a single or dual 10-12 tuned to 20-25hz is a lot more feasible.

Regards
Aniket
Mumbai

 

[prateekatasniya]

My posts are in relation to his requirement.
For his room size and budget.
He can make a subwoofer with dual iwai drivers in a sealed cabinet.
Use a crown xti amp to EQ and get frequency response flat down to 20hz or even lower.
So in this case why does he need a ported subwoofer.

Incorrect again , it's no where written that a sealed sub can play below 10hz and a ported can't. There is unloading below tuning frequency in ported sub but there are ways of mitigating that. It all depends on the SPL required and at what frequency. Sealed gives better transient response but can never go as low as ported , if you do use eq to makeup the lost lower frequency in sealed you run the risk of power compression and exceeding xmax.
Speaker design is a trade-off between achievable parameters , can't have it all.
Its good that your sub reaches 105db SPL at 9hz but that's with room gain , using a 18inch prodrivers is not always feasible in homes.
Using a single or dual 10-12 tuned to 20-25hz is a lot more feasible.

Regards
Aniket
Mumbai

I clearly mentioned about the SPL aspect.
What size do you need to achieve 10hz in a ported sub? Is that feasible ?

Almost Everyone will have room gain.
And much higher SPL is possible however presently my amp isn't powerful enough.
And under 20hz is a thing to experience.

 

[adas]

My posts are in relation to his requirement.
For his room size and budget.
He can make a subwoofer with dual iwai drivers in a sealed cabinet.
Use a crown xti amp to EQ and get frequency response flat down to 20hz or even lower.
So in this case why does he need a ported subwoofer.

Have you actually checked how much eq will be needed to reach 20hz , coz I have and it's a lot ...
A single sub ported sub tuned to 25hz can fullfill his requirements very well ..
And I think he already has a sub !!

 

[prateekatasniya]

As compared to what?

"Clean" is subjective.

In the sims that are posted where do you see the sealed sim going lower than the vented sim?

Everything depends upon the driver and it's parameters. Like the Shakira song goes - "Sims don't lie"!

I have simulated above a hundred drivers before I made my subwoofer.

Have you actually checked how much eq will be needed to reach 20hz , coz I have and it's a lot ...
A single sub ported sub tuned to 25hz can fullfill his requirements very well ..
And I think he already has a sub !!

25hz is past..
Yeah it needs EQ.. I look at the end result.. without caring about the EQ needed..
Watch movies like Aquaman etc.. With a ported vs a sealed subwoofer.. note the difference.

I have compared my ported (genelec 7060b ) with my 18"sealed sub..
I cannot go back to ported subwoofer anymore for my present room.

 

[adas]

25hz is past..
Yeah it needs EQ.. I look at the end result.. without caring about the EQ needed..
Watch movies like Aquaman etc.. With a ported vs a sealed subwoofer.. note the difference.

I have compared my ported (genelec 7060b ) with my 18"sealed sub..
I cannot go back to ported subwoofer anymore for my present room.

Tell me the power needed at 25hz with 2iwai subs ...

 

[prateekatasniya]

Tell me the power needed at 25hz with 2iwai subs ...

400 watts
105db
At 25hz
Dual 12" iwai
80 litres cabinet

consider boundary and room gain, one will get more SPL.

 

[adas]

400 watts
105db
At 25hz
Dual 12" iwai
80 litres cabinet

consider boundary and room gain, one will get more SPL.

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

 

[mpw]

a good sub will re-inforce the music instead of lower and louder being the criterion.

 

[diyaudio]

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.