10" Subwoofer simulation graphs - please add your suggestions

[Naveenbnc]

just learnt that GROUP DELAY is not at all good.
In some forums they say ideally it should be zero.... but practically it is impossible.
for low frequencies, any where between 2 to 5msecHz is good ....
Im not sure if i can achieve that .... need to work further

 

[Naveenbnc]

Gradual slope.

Once you have your box volume, tuning frequency and port dia, the simulation tool will tell you the length of the port needed.
Use 2.5" as port dia and see the results in simulation.

tried for gradual slope...... it is possible, but with that shape,...F3 is not going below 50Hz
If i try to lower F3 below 50hz, the graph is no longer gradual slope ...its coming with a big peak and a dip.
With lot of adjustments and trail and errors, I managed to keep the graph above -3dB

 

[diyaudio]

Group delay too will get lost in the room. No need to worry.

 

[Naveenbnc]

Group delay too will get lost in the room. No need to worry.

ooh....that's a relief
il give a try if i can reduce it further

 

[venki7744]

IMO group delay will be problematic in two cases:

* Integration with other components (sound takes longer to reach the sub output)
* Large variance in GD in the passband causing it sometime to sound odd (don't remember the exact technical jargon for this)

Venki

 

[diyaudio]

Group delay is lost in the room. Room reflections cause far greater delay than group delay. We dont hear direct bass, we hear bass that has been reflected several times before the ear registers as bass. Bass thus is steady state sound to the ear and not transient sound.

 

[Naveenbnc]

My small room is cluttered with too many objects. So the bass is surely reflected so many times from multiple surfaces before I hear it.

But just to see how to make it better...I tried to reduce the group delay..... But i have to sacrifice somewhere or the other like higher F3 etc.....

If I settle for higher F3, the group delay is getting reduced, and the curve is also much smooth with a gradual slope. But there is no point in building a sub with higher F3 (as far as I can think)

So il tame the group delay a little, and go ahead for the build.....

 

[diyaudio]

Sealed alignment has lower GD

 

[Naveenbnc]

Well.....if I'm correct with this below data...this driver is best suitable for ported...

 

[diyaudio]

With ported, higher GD is a given

 

[Naveenbnc]

One more question..... In the design phase...how to know if the bass will sound tight or boomy ???


I mean, what design principles we should apply to make the bass sound tight and precise???

Or how to make it sound boomy if we like ??
Any suggestions please....

 

[diyaudio]

The room is the culprit in almost all the cases. It causes wide changes in SPL across the frequency bandwidth, as much as dips of 12+dB are common.
Fast bass, slow bass, tight, boomy etc, are all terms used to describe room problems. The sub or its design is hardly the cause.
There is nothing that can be done at the design phase IMHO. The room WILL dominate the response.

Measure a boomy sub outside and the boominess disappears.

 

[Naveenbnc]

The room is the culprit in almost all the cases. It causes wide changes in SPL across the frequency bandwidth, as much as dips of 12+dB are common.
Fast bass, slow bass, tight, boomy etc, are all terms used to describe room problems. The sub or its design is hardly the cause.
There is nothing that can be done at the design phase IMHO. The room WILL dominate the response.

Measure a boomy sub outside and the boominess disappears.

Got it !!! Thank you....
I haven't tried subwoofer crawl earlier.
This time I should definitely try it .....

 

[elangoas]

Got it !!! Thank you....
I haven't tried subwoofer crawl earlier.
This time I should definitely try it .....

Hope you are planning for two subs?..

 

[Naveenbnc]

Ya....two subs will even out the bass I'm guessing. Currently I have a 12" sub. For my permanent use, il build and add one more 12" sub.

These 10" are only for fun & learning. I'm also curious to compare 10" and 12" performance. Il use these for a few months..

Later on, i may build a 2.2 by adding FR drivers to these 10" subs. (FR will be on a slim baffle without a box)

Or may be 3 way towers by adding a mid driver+tweeter.

But one thing il make sure is....il keep everything modular. So that mix and match of bass drivers, mid, or tweeter is possible by changing crossovers.

Will keep building as long as I enjoy doing it... lets see how the journey goes.

 

[Naveenbnc]

these are going to be my final set of graphs
im getting the following values ....
35.5Hz @ -3dB
28.3Hz @ -10dB

Internal box volume is around 38L (may slightly increase with bracing)

 

[Naveenbnc]

now i have to choose the size and shape of the box from the below
the left one is 12W X 16D X 20H
middle one is 12W X 12D X 30H
the right one is 15W X 15D X 15H

Of course, i haven't considered any golden ratio etc
I have a huge space crunch in my room ...so a slim and tall model may work
i can put it in any corner, and rotate it to any direction.

 

[Naveenbnc]

I have a question....if i choose the slim and tall model (middle one)
is it better to mount the driver as close to the floor as possible ???

 

[elangoas]

I have a question....if i choose the slim and tall model (middle one)
is it better to mount the driver as close to the floor as possible ???

Wish i could help you with DIY subwoofer build.. Your modelling of the enclosure is really good..

I haven't seen someone build speakers & subwoofers back to back on the forum so quickly.. Cheers..

You want to mount the driver closer to the floor for weight distribution & not letting the tallish sub tilt over accidentally?..

 

[Naveenbnc]

driver at the bottom is definitely good in terms of stability ....
when it comes to performance im not sure if placing the driver close to the floor is better ....
(bass is non directional any way ....)

Actually i just realized ... both options can be tried simply by placing the box upside down ..
Unless we add some legs (spikes etc)