Effect of using dampening in rear horns? - Page 2

bzdang · 19th September 2004, 05:14 AM

Quote:

Originally posted by BillFitzmaurice

The best damping material is high density rigid fiberglas but it's hard to find and nasty to work with; inch thick high density polyester furniture batting is a good inexpensive second choice.

Fiberglass ceiling tiles, vinyl one side, around 1/2" thick nasty fiberglass, available at home depot.

Used office-divider panels are also fiberglass, you get two panels per divider.

And all are extremely effective at absorbing sound from power tools and compressors in the workshop/garage.

Geek · 19th September 2004, 09:57 AM

@BillFitzmaurice: Ok, did the params. A wee lower efficiency though.

BillFitzmaurice · 19th September 2004, 01:27 PM

I don't know how you're getting that response; something isn't right at all. I'm getting a much flatter response with 105dB sensitivity. Show me your input parameters.

Geek · 20th September 2004, 10:46 AM

Quote:

Originally posted by BillFitzmaurice
I don't know how you're getting that response; something isn't right at all. I'm getting a much flatter response with 105dB sensitivity. Show me your input parameters.

'k

The over large VRC, LRC and TAL are simulating free space.

BillFitzmaurice · 20th September 2004, 12:29 PM

Many errors. The Sd is off by a decimal point, should be about 206 cm/sq. Es for 1 watt= 2.83 v.
Vrc and Lrc should be 0; for a rear horn you don't use the 'rear chamber' as the 'rear chamber'position is swapped to the front where the cone fires directly to air, so there is no rear chamber. The Vtc is going to be the volume of the actual rear chamber that the rear of the cone faces, in this case at least 1000 cm/3. Try these alterations and you'll see a far different result.

Geek · 20th September 2004, 11:33 PM

Ok, I shall correct all but the Sd - it is correct (see attached)

BillFitzmaurice · 21st September 2004, 12:24 PM

The Sd is 206 sq cm, not 20.6. The cone radius is about 8 cm, that makes its area 206 Cm Sq, give or take. You'd find an Sd of 20.6 in a two inch driver.

Geek · 26th September 2004, 11:11 AM

D'OH! My bad

I shouldda been smart the first time and used my converter program.

Here attached is SPL with corrected values. Look better?

Geek · 26th September 2004, 11:13 AM

I also changed the design from exponential to conical - more practical

BillFitzmaurice · 26th September 2004, 01:11 PM

Much better, and the conical thing works too. Plus, when it comes to actually figuring the geometry conical is very easy to work with.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
My 103E Rear loaded horns	shporsche	Full Range	17	15th July 2009 11:16 PM
Dampening in Tapped Horns??	atilsley	Subwoofers	25	20th June 2009 08:24 AM
Rear-loaded horns: disadvantages?	Taterworks	Full Range	4	3rd October 2007 05:22 PM
Resonance in rear horns	Jaime	Full Range	1	2nd March 2007 10:10 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

19th September 2004, 01:27 PM	#13
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	I don't know how you're getting that response; something isn't right at all. I'm getting a much flatter response with 105dB sensitivity. Show me your input parameters.

20th September 2004, 12:29 PM	#15
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	Many errors. The Sd is off by a decimal point, should be about 206 cm/sq. Es for 1 watt= 2.83 v. Vrc and Lrc should be 0; for a rear horn you don't use the 'rear chamber' as the 'rear chamber'position is swapped to the front where the cone fires directly to air, so there is no rear chamber. The Vtc is going to be the volume of the actual rear chamber that the rear of the cone faces, in this case at least 1000 cm/3. Try these alterations and you'll see a far different result.

21st September 2004, 12:24 PM	#17
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	The Sd is 206 sq cm, not 20.6. The cone radius is about 8 cm, that makes its area 206 Cm Sq, give or take. You'd find an Sd of 20.6 in a two inch driver.

26th September 2004, 01:11 PM	#20
BillFitzmaurice Banned Join Date: May 2004 Location: New Hampshire	Much better, and the conical thing works too. Plus, when it comes to actually figuring the geometry conical is very easy to work with.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)