Home Theater Forum and Systems banner

1 - 11 of 11 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
So, I've got this Tang band w8-1363sb 8" subwoofer and dayton pe100 plate sub amp that I kind of wish I hadn't bought.. I'm having a really hard time coming up with a ported enclosure design that's going to work well.. All of the designs I come up with in winISD call for extremely long ports (100+ inches) if I don't want a really high port speed.

Anyways, it got me thinking that maybe what I should just do is go with a sealed design.. It definitely means lower output, and a higher roll off on the low frequencies, but if I bump the signal up a bit coming out of my receiver (say by 3db) and go with a lower QTC then I think it might do me alright.

So if I put the sub in a .5 cu ft sealed enclosure, I end up with a transfer magnitude graph that looks like this:
http://i.imgur.com/C2K0T.jpg

The F3 is really high, like 80hz.. But if I've bumped my signal up by 3db, then my effective f3 is more like 50hz.. Is this a reasonable way to look at this?

Finally, if I do build this arrangement, Do I need to worry about filtering out the really low frequencies?

Here is the cone excursion graph in winISD
http://i.imgur.com/Dt1Mt.jpg
Why is it so low?
I was thinking I might want to add some sort of a hpf since I don't believe this PE amp has one built in, but is it a concern?

Thanks for any help on this.
 

·
Premium Member
Joined
·
19,397 Posts
Your file has the wrong Xmax, it should be 12 mm. This driver would work in a 1 cu.ft. box with a passive radiator, have you considered this option?

.3 cu.ft. sealed compared to 1 cu.ft. tuned to 22 hz with a single 10" PR from CSS.

http://creativesound.ca/details.php?model=APR10

Both modeled with the 100 watt Dayton amp which has a hi-pass filter at 18 hz.

tang band.JPG
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #5 ·
Maybe the PR is the way to go, I didn't consider that.
Is that hump between 20 and 30 hz an issue?

Your file has the wrong Xmax, it should be 12 mm. This driver would work in a 1 cu.ft. box with a passive radiator, have you considered this option?

.3 cu.ft. sealed compared to 1 cu.ft. tuned to 22 hz with a single 10" PR from CSS.

http://creativesound.ca/details.php?model=APR10

Both modeled with the 100 watt Dayton amp which has a hi-pass filter at 18 hz.

View attachment 33412
 

·
Premium Member
Joined
·
19,397 Posts
No, it's less than half a db. The actual response you get will depend on any room gain you get. The advantage of a CSS PR is you can tune the sub from the front side of the PR, adding or subtracting one washer at a time will give you the best in room response with a bit of experimenting. The 23.3 hz tuning is 6 washers, the 19.7 hz tuning is 9 washers.

css.JPG
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #7 ·
Cool. I think this is the way to go for sure.
Thanks.

No, it's less than half a db. The actual response you get will depend on any room gain you get. The advantage of a CSS PR is you can tune the sub from the front side of the PR, adding or subtracting one washer at a time will give you the best in room response with a bit of experimenting. The 23.3 hz tuning is 6 washers, the 19.7 hz tuning is 9 washers.

View attachment 33413
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #8 ·
This is an oldie.. But I finally built this. It seems to work pretty good, but I'm having to toy around with stuff to adjust for cone excursion on the sub, and group delay.. For some reason I kind of overlooked these.

I have to run a minimum of 405 grams of weight in this PR to not exceed the cone excursion of the tangband above 18hz (built in 18hz hp filter in the amp).


But the group delay is high.. And I can hear a delay when the sub is active (primarily with music, or where timing is very important)


When I lowered the weight in the PR to 270G, the delay seemed to be tolerable, but the cone excursion on the sub was being exceeded..

Any thoughts on this?
 

·
Registered
Joined
·
490 Posts
that 100w dayton amp has a hp filter at 18hz.so it may not actually be going over xmax.you need to set that filter under the eq filter tab.if you havent already.
 

·
Registered
Joined
·
261 Posts
But the group delay is high.. And I can hear a delay when the sub is active (primarily with music, or where timing is very important)


When I lowered the weight in the PR to 270G, the delay seemed to be tolerable, but the cone excursion on the sub was being exceeded..

Any thoughts on this?
It seems unlikely you can actually perceive a change in group delay at 20Hz between the two tunes especially when the group delay at 20Hz looks to be well under 100ms.

You probably more likely have an issue with the integration of the sub with the mains when using the lower tune. However, if your receiver is any good you can adjust the subwoofer distance relative to the mains in order to really dial in your sub to get it to blend with your mains where they overlap. However, this will require measuring with something like REW and making the appropriate adjustments based on the measurements and measuring after to confirm the new settings work as expected.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #11 ·
It seems unlikely you can actually perceive a change in group delay at 20Hz between the two tunes especially when the group delay at 20Hz looks to be well under 100ms.

You probably more likely have an issue with the integration of the sub with the mains when using the lower tune. However, if your receiver is any good you can adjust the subwoofer distance relative to the mains in order to really dial in your sub to get it to blend with your mains where they overlap. However, this will require measuring with something like REW and making the appropriate adjustments based on the measurements and measuring after to confirm the new settings work as expected.
Ah interesting point.. I have an Onkyo receiver with Audyssey calibration.. I ran it before having the sub, but not since.. Stupid me for not running it again. I'll try that.
 
1 - 11 of 11 Posts
Top