[fiftyone50]

Hi all, this is re: an old thread of mine.
http://www.avsforum.com/forum/155-diy-speakers-subs/1505635-diy-12w7-subs.html

Back on the table now....
6 ft/3 enclosures per 12w7. 18 Hz tuning frequency.

I think I really want to go passive radiator.
Looking at these definitive technology ones:

http://www.ebay.com/itm/Definitive-...554?pt=LH_DefaultDomain_0&hash=item27b4b448da

I'm no passive radiator expert...... Would one of these be enough to pair with a 12w7?


Or maybe two of these?

http://www.ebay.com/itm/Definitive-...777?pt=LH_DefaultDomain_0&hash=item2eae49fbc1

Any help appreciated. Thanks much!

 

[LTD02]

passive raditors have statistics that help determine how they will function.
I didn't see them listed.
vas qms fs sd xmax etc.

 

[fiftyone50]

Definitive won't release the "proprietary specs" of the radiators. :/

I was hoping someone had some somewhere, to get an idea on the excursion. They look pretty healthy, and the SD should be bigger than the 12w7 cone....

I assumed since the tuning is adjustable on radiators, that it should be easy enough to figure out where the tuning is at, and tweak it from there, I just want to be sure I have enough radiator for the active sub, so it doesn't just annihilate.

 

[Jay1]

Well If I take this 15" pr with 33mm of throw

http://creativesound.ca/details.php?model=APR15

and put it in a 6ft3 box with 405g added mass for an 18hz tune, and add an 18hz high pass filter it only takes 300 watts to bring the pr to its full 33mm excursion. The 12W7 can handle 1500 watts in that box. You really need two of the 15" prs

 

[fiftyone50]

That sounds like a lot of mass to get there.... and doubling the radiating surface then requires doubling the mass?
I would've figured a bigger Sd PR with more as much or more stroke would've been close.

 

[Jay1]

That sounds like a lot of mass to get there.... and doubling the radiating surface then requires doubling the mass?
I would've figured a bigger Sd PR with more as much or more stroke would've been close.

The APR15 that I linked come with 900g of mass discs (20ea 45g discs). A pair of those PRs with 810g added to each in 6ft3 will tune you right at 18hz. Add an 18hz HPF an you could put 1200 watts on the JL before PR excursion becomes an issue.

 

[noah katz]

Well If I take this 15" pr with 33mm of throw...

Not sure that's a useable 33 mm; it says "Xsus", which may mean that the suspension is taut.

If that's the case output may have started to compress well before that.

 

[fiftyone50]

The APR15 that I linked come with 900g of mass discs (20ea 45g discs). A pair of those PRs with 810g added to each in 6ft3 will tune you right at 18hz. Add an 18hz HPF an you could put 1200 watts on the JL before PR excursion becomes an issue.

Would you happen to know if multiple PR's are used @ different masses (tunings), what the effect would be?

Also, you seem to be "on" the modeling this stuff, how does a 12W7 model with 3 of the 12" APR's?
Should be roughly similar Sd, with enough excursion?

I'm thinking about throwing an inuke 6000dsp at the pair of subs. I thought about twin 3000s but P.E. says don't go lower than 4 ohm mono. Headroom is good, especially with lows.

I might also drop to a little smaller cabinet /higher freq ~4.5ft/3 (+/-), I was originally shooting for pretty flat 20-20k, then was suggested to try for even lower.... which sounds good in theory, but I really won't use these but for music - and don't listen to much pipe organ. Plus, who knows what kind of actual in room response there will be, until they're actually in the room? They will be crossed over low.... under 50hz for sure, my mains won't really need help at 35-40hz.

I don't *mind* a big box, but want the performance to be worth the extra size.
Between that, and I can hear port noise exceptionally well, are part of why I'm at the PR approach.
I like watching diaphragms flex thru excursion also...

 

[Jay1]

Would you happen to know if multiple PR's are used @ different masses (tunings), what the effect would be?

Also, you seem to be "on" the modeling this stuff, how does a 12W7 model with 3 of the 12" APR's?
Should be roughly similar Sd, with enough excursion?

I'm thinking about throwing an inuke 6000dsp at the pair of subs. I thought about twin 3000s but P.E. says don't go lower than 4 ohm mono. Headroom is good, especially with lows.

I might also drop to a little smaller cabinet /higher freq ~4.5ft/3 (+/-), I was originally shooting for pretty flat 20-20k, then was suggested to try for even lower.... which sounds good in theory, but I really won't use these but for music - and don't listen to much pipe organ. Plus, who knows what kind of actual in room response there will be, until they're actually in the room? They will be crossed over low.... under 50hz for sure, my mains won't really need help at 35-40hz.

I don't *mind* a big box, but want the performance to be worth the extra size.
Between that, and I can hear port noise exceptionally well, are part of why I'm at the PR approach.
I like watching diaphragms flex thru excursion also...

I'm pretty sure the cabinet will only tune to a single frequency even if you have prs with varying mass. There isnt any way to predict the results that I know of other then seeing for yourself.

3 APR12s would work very well. If you're not using this sub for movies and plan on crossing under your mains there may not be any reason to bother with a sub like this honestly. Anyway, a 4 ft3 box with 3 APR12s with 630g mass each will get you right at 20hz. You should be good for using a nu6000dsp with a 20hz filter in place. PR excursion is reached with 1650 watts.

 

[fiftyone50]

I'm pretty sure the cabinet will only tune to a single frequency even if you have prs with varying mass. There isnt any way to predict the results that I know of other then seeing for yourself.

3 APR12s would work very well. If you're not using this sub for movies and plan on crossing under your mains there may not be any reason to bother with a sub like this honestly. Anyway, a 4 ft3 box with 3 APR12s with 630g mass each will get you right at 20hz. You should be good for using a nu6000dsp with a 20hz filter in place. PR excursion is reached with 1650 watts.

I think I might end up snatching a few of the definitive tech 14"s after all. They dropped in price to $60.
Given the ease in changing tuning, I figure they're worth a shot, specs or no.... at the price.

Yes, no sub was necessary to begin with, but I've run one and it brought up the lows noticeably.
I have 2 12w7's and 2 13w6v2's laying around that aren't going in cars though, I was planning to use the 12's in the music sub pair, and thought about building a twin 13w6 big sub to augment the preludes in my theater.

Decisions, decisions.... lol