The audio bug has bitten--again (wife rolls eyes)

[18Hurts]

Hello All!,

The perfect storm hit, I retired from the military so my "audio gear" that was in storage was placed into my hot little hands. My youngest son hit 18 so I can kick is **** if he nukes it (and won't be charged with child abuse) and those Cerwin Vega V-15B PA speakers were taking up space.

Took a look at the pile, 1999 Infinity Overture 1 (MTM w/8" powered woofer), Onkyo receiver (around 60 WPC surround) 1994 Sony CD player, AR 12" subwoofer and my vintage 1988 Carver M1.5t amplifier.

Wired it up (fixed some problems on the Onkyo) and fired it up. It all worked but I wanted to get louder, lower and deeper bass that went to 18 Hertz... the AR was not cutting it. Took the Cerwin Vega PA speakers apart, repaired a small rip in one of the cones and removed the mid/tweet horns. Measured everything out and had a 3.8 cubic foot with 3/4" thick plywood walls to play with. The closest I could find to match my W15P woofers was their XL version so I went with that.

95dB sensitivity, 7.3 cubic foot Vas, 4.5mm Xmax, 4 ohms, 300W RMS, .394 Qts and 35 Hz Fs which goes along with it being a PA woofer. One of the woofers worked fine but had the patch on the cone and ironically, my cabinet with horns and ports removed was 3.65 cubic feet when accounting for driver displacement. Isobaric anyone?

Went with the Isobaric since it would match perfectly the 7.3 cubic foot Vas AND it would "hide" the woofer that had the patch...and handle the 750 watts of headroom the M1.5t does when running on one channel. Went sealed for awhile, checked it with my Rad Shack meter corrected out to F3 of around 34 Hz. Seemed like a crime to put an Iso group in a sealed box but I'm not a big fan of ported. My old Klipsch Tangent 50s ran a passive radiator in the back so I read up on those--no port noise, easily tuned by adjusting the weights and by adding another 1.5" of plywood on the back, it would clear the sides by quarter inch.

The old Cerwin Vega PA speaker sits there with a face to face clamshell isobaric group with the outer speaker "backwards". I cut the front face off the other PA speaker and mounted it so the grills will cover the "backwards woofer" My wife appreciated that! The Exodus Audio PR18 (18" passive) was loaded to 2.25 pounds total weight and a final tune of 21.4 Hz. Hauled it over to the corner, wired it for 8 ohms (two 4 ohms in series) and fired it up. Played the 1812 Overture and my wife jumped when the cannons fired--she said "Is THAT the passive?" Guess it worked if you wife notices the difference.

Luckily, the box is now 22" deep weighs over 90 pounds so resists rocking when that heavy passive gets motivated. It will vibrate the floor strongly when it gets highly motivated which works well in movies.

Then a buddy of mine has a spare Eclipse 8200 dual 4 ohm voice coil aluminum cone 12" sub that he will give me. Xmax of 32mm, Vas 3.2 cu ft, Fs of 27Hz and insane power handling. Hmmm....what can I do with that?

Then I saw tapped horns--that seems to be the direction I want to go. 8 foot tall sub? Sure! But first, I'll have to finish the surround sound system so I'm thinking Zaph Audio 5" MTM type center channel that I'll build then maybe two Pioneer 8" full ranges to experiment open box for surround effects. If I don't like the open box/baffle--install phase plug--add glue to the cone and have fun experimenting with it. $19 a pop...it will be the hobby part of the bug.

Sorry to make such a long first post--it feels good to be back into the audio realm, 15 years out of it the stuff looks different but Hoffman's Iron Law is still intact. Bose still sells trash but it costs more...some things never change.

Eager to learn horns and tapped horns... my wife might bury me in one--it is about the right size. I promised her THIS time--the bug won't be so expensive...I promise...trust me!

[planet10]

Welcome to the forum

A PR box is a BR. 7.2 ft^3 is big, but not in comparison to the 28.8 fy^3 you'd need if you put the drivers in the box not-isobarik

dave

[SY]

Glad you de-lurked. When I explained to my wife what a horn woofer was, she explained to me what alimony was.

[18Hurts]

Thanks Dave!,

Sorry, I was a little unclear (been awhile!) The box is 3.65 cu. ft. so the Iso group "sees" 7.3 cu. ft. It works well, I tested it with the corrected Rad Shack meter for +3/- 0 dB in the 20 to 40 Hz octave--the 20Hz reading was + 0.5 with at +3 dB rise at 30 to 32Hz. It seems the Fs on my well worn 20 year old woofers dropped from 35Hz to around 31 Hz? I'll have to test it with my amp meter to make sure.

My wife is happy since I got rid on one of the speakers and the PA converted to subwoofer project actually works. She is not too enthused over the idea of an 8 foot 18 Hz tuned tapped horn though. I told her to relax, I have to learn how to model it first so that should take all winter. She does like the idea of finishing the surround sound project so I'm not shacking up with the dog yet.

[DualTriode]

Hello 18Hurts,
Welcome and thank you for your service.
DT
All Just for fun!