Tuning of subwoofer?

[cameron paterson]

Should an enclosure thats tuned at say 34hz have a HPF of 34hz crossover as well?

 

[HuenEye]

No, unless your main speakers also go down to 34 Hz. You need to match the sub to your speakers to get a smooth transition. You need to use REW (I use a Velodyne SMS) to see how low your speakers go.

BTW, you would have to spend a lot of $$$ to get a HP or LP that crosses at 34 Hz as the inductors would have to be HUGE. I design my own crossovers and know prices and I thought of doing something similar for the heck of it and when I looked at the components needed . . . and the size of the inductor, I realized it wouldn't even fit in the speaker enclosure.

 

[ryanosaur]

This is where usage of DSP comes in handy, for managing Subs. And if you don't have a built-in XO on your Receiver, you either do so again with DSP or leave the Speakers to play their full range and manage Subwoofer integration on its own.
Using REW or other measurement program is absolutely a must for fine tuning these systems.

 

[ski2xblack]

Cameron's question is unclear, but he seems to be asking about a hpf to protect a reflex loaded sub on the low end, which is advisable, to prevent damage to the driver. His mains roll off at 120hz or so.

 

[HuenEye]

Cameron's question is unclear, but he seems to be asking about a hpf to protect a reflex loaded sub on the low end, which is advisable, to prevent damage to the driver. His mains roll off at 120hz or so.

If the sub was designed to be used in a ported or other open design you have no worries as that is what they were designed for.

 

[ski2xblack]

What you fail to realize is that Cameron's subs are diy affairs, so any hpf or limiters that a commercial product would employ need to be accounted for. Without such protection, if he feeds a 120db 20hz signal to what he describes in his first post, it is a recipe for driver damage.

 

[ski2xblack]

Should an enclosure thats tuned at say 34hz have a HPF of 34hz crossover as well?

I failed to actually answer. Apologies, Cameron. I think a hpf of 24db/oct. at 25hz would be sufficient. You could use a higher freq if necessary (if you still have an even larger sub you're trying to blend with), but knowing how you'll likely beat on it, I wouldn't go any lower.

 

[TLS Guy]

I failed to actually answer. Apologies, Cameron. I think a hpf of 24db/oct. at 25hz would be sufficient. You could use a higher freq if necessary (if you still have an even larger sub you're trying to blend with), but knowing how you'll likely beat on it, I wouldn't go any lower.

He is using a pro driver that is as tough as nails. I don't think he needs to high pass it, but just let if roll off with its native roll off below F3, which will be 24 db/octave.

 

[ryanosaur]

He is using a pro driver that is as tough as nails. I don't think he needs to high pass it, but just let if roll off with its native roll off below F3, which will be 24 db/octave.

Unless he is boosting it... which is all too common in the DIY field right now. *shrugs

We are speculating here... Cam hasn't posted anything since OP in October and it was a thread-surrection which we are all responding to.

If the Driver/Sub is being boosted at the tuning frequency, then a protective HPF is usually advised. Assuming the box and port tune are appropriate for the Driver, this might not actually be necessary.

On the other hand, if the box and port are pushing extremes, and/or the Driver is being boosted near its limits...

I believe "dog's lunch" is the phrase you like to use sometimes.

Without Cam chiming in... all of this is pretty pointless, though.

 

[TLS Guy]

Unless he is boosting it... which is all too common in the DIY field right now. *shrugs

We are speculating here... Cam hasn't posted anything since OP in October and it was a thread-surrection which we are all responding to.

If the Driver/Sub is being boosted at the tuning frequency, then a protective HPF is usually advised. Assuming the box and port tune are appropriate for the Driver, this might not actually be necessary.

On the other hand, if the box and port are pushing extremes, and/or the Driver is being boosted near its limits...

I believe "dog's lunch" is the phrase you like to use sometimes.

Without Cam chiming in... all of this is pretty pointless, though.

I have worked with this guy enough that I think he knows he can not do that. He wants to use this unit for what he calls mid bass slam.

By the way you should never boost a ported sub. It is useless, damaging and under no circumstances should it be attempted.

 

[ryanosaur]

By the way you should never boost a ported sub. It is useless, damaging and under no circumstances should it be attempted.

I agree. I've seen a lot of folk talk about doing silly things, though.

For me, I don't know what I don't know. And what Cam is actually doing qualifies for that category.

 

[lovinthehd]

Unless he is boosting it... which is all too common in the DIY field right now. *shrugs

We are speculating here... Cam hasn't posted anything since OP in October and it was a thread-surrection which we are all responding to.

If the Driver/Sub is being boosted at the tuning frequency, then a protective HPF is usually advised. Assuming the box and port tune are appropriate for the Driver, this might not actually be necessary.

On the other hand, if the box and port are pushing extremes, and/or the Driver is being boosted near its limits...

I believe "dog's lunch" is the phrase you like to use sometimes.

Without Cam chiming in... all of this is pretty pointless, though.

@cameron paterson has been around....a coupla weeks ago in another thread at least.

 

[cameron paterson]

Could someone please model this sub for me:
B&C 18TBW100-4 18" Professional Subwoofer 4 Ohm (parts-express.com)
The parameters are on the website
I have my reasons to build this subwoofer box this way!
A box that has a 3" high x 20" wide x 22" deep port. tuned at 30hz and 6.5ft3.
I have my reasons. Could you please model this with excursion and SPL and air velocity?

 

[cameron paterson]

Is this correct?

Subwoofer Enclosure Calculators, Parallel, Series, Port Length and Volume (the12volt.com)

Go to Slot Port Length Calculator.
Port width 20" x Port height 3" x Box volume 6.5ft x Tuning frequency 30hz = 21" for the length of the port. Is this the correct length of the port for a 30hz tune?

 

[cameron paterson]

I don't boost any of my subs I run a HPF right where the box is tuned at, at 12db/oct. I have a box tuned at 34hz. Should I have a HPF more like 30hz at 12db/oct?