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PostPosted: Fri Mar 10, 2017 9:05 pm 
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I don't think these are suited for that. They appear to do best with small box volumes but F3 won't be very low. The original sealed enclosures only left about .5CF of air volume after amp and speaker displacement. This is sealed of course. I'm sure the amp did have some bass boost.


dr.joe wrote:
What's the sensitivity of those subwoofers?

I'm on a quest to defy Hoffman's Iron Law: subwoofers that will have an f3 no higher than 32 Hz, in a cabinet of no more than 170 litres (6 cf), with a sensitivity of no less than 95 dB!

TIA,

Joel.


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PostPosted: Sat Mar 11, 2017 3:58 am 
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those are more like 86 d/b 1 watt /meter type of driver, any real subwoofer drivers are all very low sensibility.


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PostPosted: Sat Mar 11, 2017 5:46 am 
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Location: Waterdown, ON, CA
dr.joe wrote:
What's the sensitivity of those subwoofers?

I'm on a quest to defy Hoffman's Iron Law: subwoofers that will have an f3 no higher than 32 Hz, in a cabinet of no more than 170 litres (6 cf), with a sensitivity of no less than 95 dB!

TIA,

Joel.


:shock: Good luck with that.


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PostPosted: Sat Mar 11, 2017 6:51 am 
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svtcontour wrote:
I'm going to measure the parameters tonight and see what kind of sub I can DIY out of them :)


I'm not familiar on how to measure the parameters of a driver.

Is this the method you used ?
http://sound.whsites.net/tsp.htm

If not, is there a reference for your measurement method ?


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PostPosted: Sat Mar 11, 2017 7:33 am 
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Location: Toronto, ON, CA
Teo Audio wrote:
So you are looking for a slot loaded 24" with a ++20lb magnet structure. As for the box loading, it may not work in 6 cubes.

It might if you fib a bit and go transmission line. Then you can hit your 32hz at 95db at 1 watt. Maybe. It's real real close.

With room lift added in, it should be doable.


Teo Audio,

You're right, I don't see a 24" driver workilngin a six cubic foot cabinet. But, for that matter, I don't see using a 24" driver. I had a pair of 21" subs for a short while, in sealed cabinets, but I got better LF response from a pair of 18" drivers in 7 cu.ft. ported cabinets.

It may be best, in the end, to stick to a pair of TAD TL-1601b in 170 litre cabinets: they're okay to 32 Hz, though the sensitivity has fallen quite a bit by that point. EQ like the old subwoofer designs for the JBL 2235 and 2245 drivers?

From what I've seen so far, transmission line designs are usually lower sensitivity than bass reflex designs. Can you suggest any sources for the type of transmission line designs you have in mind?

Thanks!

Joel.


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PostPosted: Sat Mar 11, 2017 8:37 am 
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That will work but an easier way would be to purchase the Dayton woofer tester.

Uunderhill wrote:
svtcontour wrote:
I'm going to measure the parameters tonight and see what kind of sub I can DIY out of them :)


I'm not familiar on how to measure the parameters of a driver.

Is this the method you used ?
http://sound.whsites.net/tsp.htm

If not, is there a reference for your measurement method ?


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PostPosted: Sat Mar 11, 2017 10:27 am 
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May I suggest you build two cabinets and run one driver per box. Front loaded or downward firing. They both have their pros and cons but building a larger cabinet and arranging two drivers to work in tandem and not interfere with one another is for the boys that know what they are doing. Not a recommended DIY project. Not saying it can't be done but without knowing all the parameters of the drivers as well as a proven cabinet design, you may create a large box of disappointment.

J.


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PostPosted: Sat Mar 11, 2017 11:02 am 
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There wouldn't really be any interference as long as the T/S parameters are very close between the drivers (need to be measured). In close proximity to one another in the same airspace, they will couple. The key is to do the measurements first and ensure there is no large variance between the drivers. Bracing can also be an issue with a larger cabinet but that's part of the build. Having two separate subwoofers would be better for integration into a room so there is a plus that way as well.



Prosoundman wrote:
May I suggest you build two cabinets and run one driver per box. Front loaded or downward firing. They both have their pros and cons but building a larger cabinet and arranging two drivers to work in tandem and not interfere with one another is for the boys that know what they are doing. Not a recommended DIY project. Not saying it can't be done but without knowing all the parameters of the drivers as well as a proven cabinet design, you may create a large box of disappointment.

J.


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PostPosted: Sat Mar 11, 2017 11:42 am 
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svtcontour wrote:
That will work but an easier way would be to purchase the Dayton woofer tester.

Uunderhill wrote:
svtcontour wrote:
I'm going to measure the parameters tonight and see what kind of sub I can DIY out of them :)


I'm not familiar on how to measure the parameters of a driver.

Is this the method you used ?
http://sound.whsites.net/tsp.htm

If not, is there a reference for your measurement method ?

Old school method works fine if you already have the equipment. Otherwise, the Dayton audio tester looks to be a snap.

_________________
To a hammer, everything looks like a nail


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PostPosted: Sat Mar 11, 2017 11:59 am 
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When coupling identical drivers, the trick is to place them in separate chambers with different tuning. Otherwise the resonant peaks of the two drivers being the same and coupled will produce an even larger peak centred at one frequency. It is much preferred to have two smaller bumps as opposed to one very large one when you are striving for as linear a response curve as possible. This is why I suggest building two smaller cabinets; one for each driver which can be placed in a more traditional stereophonic set-up. You will have more flexibility with placement. Unless you have a proven design for twin 10 inch woofers, I fear your results will be less than ideal. If you insist on going forward with a two driver-one cabinet design, I would strongly recommend a push-pull configuration.

That's my 3 1/2 cents worth.


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PostPosted: Sat Mar 11, 2017 2:15 pm 
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if I was you. you say they are the same as used in revel sub B 110. so take same cabinet measurement. they did all the research for you. just copy them.


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PostPosted: Sat Mar 11, 2017 2:28 pm 
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svtcontour wrote:
Ya they are sweet. Now they are not suited for ultra low HT bass as I measured their FS at 34 and qts of .34, but they will make for very clean snappy bass for music. Something paired with some small bookshelf speakers. Also the suspension is silent which is nice.


alladione wrote:
wow awesome !!!!!
Thx

The manual claims a -3db of 28Hz anechoic which should be good to 20Hz in room.
http://www.specsserver.com/CACHE/MEYYDFKGVMLT.PDF


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PostPosted: Sat Mar 11, 2017 8:10 pm 
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That's with the help of bass boost from the original amplifier to lift the low end when placed in a small cabinet. Without the original amp relying on the low end lift, we're now dealing with the natural response of the drivers only within the cabinet.

oddio1 wrote:
svtcontour wrote:
Ya they are sweet. Now they are not suited for ultra low HT bass as I measured their FS at 34 and qts of .34, but they will make for very clean snappy bass for music. Something paired with some small bookshelf speakers. Also the suspension is silent which is nice.


alladione wrote:
wow awesome !!!!!
Thx

The manual claims a -3db of 28Hz anechoic which should be good to 20Hz in room.
http://www.specsserver.com/CACHE/MEYYDFKGVMLT.PDF


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PostPosted: Sat Mar 25, 2017 6:44 am 
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Location: Regina, SK, CA
+1 for the Dayton audio tester. Its easy to use and accurate as anything else available to the DIY'er

LIMP is another worthwhile tool to measure T/S and its free. You need to build a jig to make it all work. http://www.artalabs.hr/


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