Dr V's Twin Acoupower 18" Build - Page 9 - Home Theater Forum and Systems - HomeTheaterShack.com

 View Poll Results: Ported or Sealed? Yellow -Sealed LT 7ft. 13 30.23% Purple - Ported 14ft. Tuned to 15hz 26 60.47% Orange - Ported 16ft. Tuned to 21.68 Hz 1 2.33% Green - Ported 20cft. Tuned to 18Hz 3 6.98% Voters: 43. You may not vote on this poll

Old 02-14-08, 12:24 AM
CIBELTRAN
Inactive

Posts: n/a
Re: Dr V's Twin Acoupower 18" Build

Noah,

I agree part of this is counterintuitive.....you are almost there.....let's hit the definition:

Entrainment (According to Merriam-Wesbter):

Transitive Verb:
1 : to draw along with or after oneself
2 : to draw in and transport (as solid particles or gas) by the flow of a fluid

And lets look at this first phrase from Wikipedia:
"One fluid moving in another can push or pull the other along with it."

Let's talk about the air moving through a typical 4" port tube at pretty high level- just to have a scale most people here can relate to. The outflows, as discussed earlier, leave the port tube like a jet of water. The inflows, grab air evenly from all around the port tube opening. Now imagine you are a chunk of air out in front of the port tube by about 1 ft. Every time the port blows out, you are going to get pushed away from the port. When the port sucks back in, you don't feel much at all. When this happpens to you several times in a second....the net result is you get pushed back. More over, and more importantly, once you get moving, you will tend to take your neighbors with you. This is what entraiment really is.

In the case of the Acoupower driver, there is a net DC airflow behind the driver. The air around the back hole is getting sucked into the hole, and tossed out rather violently straight our the back. As the hardware video on our site shows....this airflow is pretty serious.

Well, it is late....I hope this helped. Dr. V., it is not the Whos down in Whoville you should be thinking about, it is the Grinch himself.

Time for

Carlos

Old 02-14-08, 01:50 AM
Noah

Join Date: Jun 2007
Location: Mountain View
Posts: 75
Re: Dr V's Twin Acoupower 18" Build

Carlos,

Ah, so you were saying that the DC flow is in the area behind the driver, moving heat away, not that there was a DC flow through the driver.

Right?

I'd still like to know what happens w/continuous high power in a sealed and stuffed box.

I presume it wouldn't last long, as has been pointed out, average power in any realistic usage situation will be a fraction.
noah katz is offline
Old 02-14-08, 07:46 AM Thread Starter
Senior Shackster
vinculum

Join Date: Feb 2007
Location: York, Pa.
Posts: 105
Re: Dr V's Twin Acoupower 18" Build

This entrainment is an interesting subject. Since you use port flow as an example, i would assume this also happens on the other side of the port, on the inside of a box.

A Passive radiator design would completely eliminate the chance of any noise emanated from the driver being heard outside the box.

However from a thermal standpoint, Noah brings up a good question about power dissipation from a closed box. Acoupower's website's recommended enclosure page tells us that "the 18 inch driver in a 5-6cuft box is awesome." I know from our talks, this is a closed box. Sealed enclosures might be best built out of thick aluminum plate, like the one Funk Waves did on that LMS4000. http://www.hometheatershack.com/foru...m-lms4000.html

I'll try and keep that Grinch guessing!
Dr V
vinculum is offline
Old 02-20-08, 01:04 AM
Senior Shackster

robert

Join Date: Jan 2008
Location: new orleans
Posts: 464
Re: Dr V's Twin Acoupower 18" Build

Just came across this thread. Believe it or not, right around the time acoupowe came up on the web, I was starting to look into building my LFE speakers. I really thought they were the coolest looking things I ever saw. I definitely like the tooling and the surround is a dynamite design. Well, I started looking more and more and then came across all the other subs including the 5400. I went back and forth on acoupower-5400. I even went as far as designing enclosures for the acoupowers with those glorious ports. Lots of back and forth, But I could not get enough info to make the actual purchase. Then, one day when I decided to get the acoupowers and the ports, I could not get the web site, and I could not get an answer on the phone. I tried going through "Bully" website, but nothing. I was crushed. TC was my choice, but even then it took me almost a year to decide which ones and how many. Anyway, I am currrently building a system with 4 5400's and 8 passives as some of you know, and I MUST finish this. It is really starting to eat at me.

BUT, I will be purchasing these acoupowers because I feel that they will live up to the levels of performance that Carlos states. I talked to him as soon as I heard the website might come back. I called him at about 2 in the morning just to see if the answering machine would pick up and the co. really was ready to sell these monsters to us again. He answered the phone and we chatted for a while. He answered all my questions personally and seems to know his driver very well. All you have to do is look at the drivers and see that the materials are top notch and all the tooling is not just off the shelf.

Well, sorry to be so long winded, but I really think you made a good choice with the acoupowers. Can't wait to see the build and get some listening or "feeling" results going.

Good luck Dr. V,

Robert

Hey Ilkka, what about the dampening material? Any info?
robertcharles123 is offline
Old 02-20-08, 02:57 AM Thread Starter
Senior Shackster
vinculum

Join Date: Feb 2007
Location: York, Pa.
Posts: 105
Re: Dr V's Twin Acoupower 18" Build

Hi Robert.

I've been following your threads both here and on AVS with great interest. (Also Michael Hurd's Beast clone). I do recall reading you almost got the Acoupowers. Funny thing is I almost bought the 5400's, then THEY were gone!! You made a great choice acquiring them with matching PRs. After Ilkka's tests, I'm certain many people wish they could have the drivers & PRs you are sitting on! I'm almost certain I'm going to go the PR route as well. Just getting some behind the scenes help before proceeding.

Good luck with project as well. It appears is won't be long before it springs to life!

Dr V
vinculum is offline
Old 02-20-08, 11:55 AM
Senior Shackster

robert

Join Date: Jan 2008
Location: new orleans
Posts: 464
Re: Dr V's Twin Acoupower 18" Build

How is the design and build coming. I was thinking of replacing my pedestal for the seating and creating a sub using the acoupowers, but space will be a definite consideration. Are you going with the sonotube design?

Thanks,

Robert
robertcharles123 is offline
Old 03-27-08, 03:41 AM
Senior Shackster

robert

Join Date: Jan 2008
Location: new orleans
Posts: 464
Re: Dr V's Twin Acoupower 18" Build

How far along are you on this project?
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Old 03-31-08, 12:45 AM Thread Starter
Senior Shackster
vinculum

Join Date: Feb 2007
Location: York, Pa.
Posts: 105
Re: Dr V's Twin Acoupower 18" Build

Not much new to report Robert. Other projects have taken priority. This thread will be updated accordingly.

Today I receive my new pre/pro! (Onkyo PRO-SC885P) My signal chain will totally balanced and I'll have all the latest HDMI audio decoders with Audyssey, THX, Burr Brown DACS. Best of all, my settings won't go out the door when I have to unplug for lighting storms, like they do with my Harmon Kardon 635. Harmon Kardon also imposes a MANDATORY high pass filter on the LFE channel with 15Hz the lowest setting possible. I like options. This unit is one GREAT bargain.

Dr V
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Old 03-31-08, 12:14 PM
Senior Shackster
Arthur

Join Date: Jan 2008
Posts: 120
Re: Dr V's Twin Acoupower 18" Build

I feel the mandatory High Pass filter is not a negative. With a tune around 17-18Hz you would be protected.

For sealed,I fully understand and can see why the high pass is not a bonus. Perperly done sealed need no high pass,I model sealed now to 5Hz. You know Bosso's arguments have merit.
TheEAR is offline

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