seems to me the prime reason to use isobariks is to reduce distortion and box size.
now to attain the same sens as 1 12" woofer they need 4 (2 isoarik sets) that is the tradeofff. so in effect they are using a box that is a bit larger than that required by 1 woofer. keeping the same sens of a 1 woofer box and reducing distortion.
now to attain the same sens as 1 12" woofer they need 4 (2 isoarik sets) that is the tradeofff. so in effect they are using a box that is a bit larger than that required by 1 woofer. keeping the same sens of a 1 woofer box and reducing distortion.
I only became aware of this thread today, but I will give some input. Eggelston is still in business. Here is the link:
EgglestonWorks
I can't comment on the company today, but I knew Bill (and his father) and visited the factory several times. Bill sold his share of the company and left to work for Chello in about 1998.
The Andra was the speaker that was named speaker of the year by Stereophile. It was named after his sister. The base in the Andra was a ported Isobaric. The space between the base drivers was sealed and the back chamber was vented in the back. The midrange was not isobaric, but was two transmission lines with one driver each. The speaker had an efficiency of 87dB and was rated at 8 ohm with a minimum impedance of 5.6 ohms. Bandwidth was +/- 3dB from 18 Hz to >24 KHz. The review can be found here:
Stereophile: EgglestonWorks Andra loudspeaker
Bill's father was William Eggleston. More about him here:
William Eggleston - Wikipedia, the free encyclopedia
EgglestonWorks
I can't comment on the company today, but I knew Bill (and his father) and visited the factory several times. Bill sold his share of the company and left to work for Chello in about 1998.
The Andra was the speaker that was named speaker of the year by Stereophile. It was named after his sister. The base in the Andra was a ported Isobaric. The space between the base drivers was sealed and the back chamber was vented in the back. The midrange was not isobaric, but was two transmission lines with one driver each. The speaker had an efficiency of 87dB and was rated at 8 ohm with a minimum impedance of 5.6 ohms. Bandwidth was +/- 3dB from 18 Hz to >24 KHz. The review can be found here:
Stereophile: EgglestonWorks Andra loudspeaker
Bill's father was William Eggleston. More about him here:
William Eggleston - Wikipedia, the free encyclopedia
Why Would You Copy This?
Stereophile's measurements of the $15,000 Andra loudspeaker, shown below:
For the moment, let's set aside the "can bad measurements sound good" controversy and look at the issues of duplicating what looks like a idiosyncratic crossover design. On paper, there are serious phasing and HF level-match issues. Based on the subjective review, it didn't sound that way.
Unfortunately, we have no way of knowing why that particularly reviewer had that particular experience. Maybe they like a certain kind of music; maybe their power amp, CD player, or phonograph has a complementary coloration. We just don't have enough information to go on - which puts the hobbyist that might want to build a "clone" in a very difficult position. To really duplicate the subjective result that the reviewer experienced, you'd need to duplicate not just the speaker (and do so exactly), but their complete system and living room as well - and share their musical tastes.
I've been to the homes of magazine reviewers - and to be honest, I found the sound to utterly bizarre - not even close to good, never mind the best. They probably felt the same way about my system. Based on those experiences, all I can conclude it is risky to assume that you, me or any reader of this forum might have the same tastes as a magazine or internet-site reviewer. To rephrase that, unless you've heard their system for yourself, with your choice of music, the subjective aspect of the review, and the product rating that goes with it, has no meaning.
Sorry to burst any bubbles here, but reviewers aren't gods - they meet the editor's deadlines, and can write to suit the magazine's style guide. Beyond that, anything goes.
OK... I really don't get it. Anytime that I've asked a question in the past that makes reference to an incrediblyh successful manufacturer and their design choices... I usually get a bunch of huge egos that could obviously blow this manufacturer away with their incredible design knowledge. ....and the reason that they aren't as successful as the big designer is because they won't sell out.... like say Mark Levinson or Mondial. C'mon.. please give me a break just this once. All the all of you "sour grapes" people to go to another thread. ....and if it makes you fel better.. then I agree... The world is flat and the emperors new robe is gorgeous. Now for those of you that are real scientists and ask the question "Why it might work?" as opposed making statements about "why it won't work." Well.. Welcome to this thread. We may even start a new trend of optimistic/open minded speaker builders as opposed to the "you're going to fall off the end of the world" type. Afterall, we all know that you can't send sounds thousands of miles away without wire, right? OK.. are all the chest pounding Yahoos gone? LOL.. that may actually include everyone that frequents this website. I guess we'll see.
So.... Any ideas on Eggleston's design choice? Remember, I've already heard all of the "you can't" statements that Eggleston, Wilson Audio, and Carver have obviously not. Let's see if we can figure out why those poor misinformed individuals chose to make such a poor choice OK.. sorry to be so wordy, but "Polarity Responders" belong in later phases of design development. After you've done 90% of what they'll tell you isn't possible.
Stereophile's measurements of the $15,000 Andra loudspeaker, shown below:
For the moment, let's set aside the "can bad measurements sound good" controversy and look at the issues of duplicating what looks like a idiosyncratic crossover design. On paper, there are serious phasing and HF level-match issues. Based on the subjective review, it didn't sound that way.
Unfortunately, we have no way of knowing why that particularly reviewer had that particular experience. Maybe they like a certain kind of music; maybe their power amp, CD player, or phonograph has a complementary coloration. We just don't have enough information to go on - which puts the hobbyist that might want to build a "clone" in a very difficult position. To really duplicate the subjective result that the reviewer experienced, you'd need to duplicate not just the speaker (and do so exactly), but their complete system and living room as well - and share their musical tastes.
I've been to the homes of magazine reviewers - and to be honest, I found the sound to utterly bizarre - not even close to good, never mind the best. They probably felt the same way about my system. Based on those experiences, all I can conclude it is risky to assume that you, me or any reader of this forum might have the same tastes as a magazine or internet-site reviewer. To rephrase that, unless you've heard their system for yourself, with your choice of music, the subjective aspect of the review, and the product rating that goes with it, has no meaning.
Sorry to burst any bubbles here, but reviewers aren't gods - they meet the editor's deadlines, and can write to suit the magazine's style guide. Beyond that, anything goes.
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I've had two isobariks in my life, the first one was a 1991 B&W isobarik small subwoofer mixed with a pair of JBL ProIII speakers. Very small sub and it went deep--not very efficient but had great sound quality.
The second isobarik sub is sitting in my living room. Had a pair of Cerwin Vega V15E PA speakers in really nice 3/4" ply boxes with blown midranges. Found the specs on the woofers--calculated the correct box size at around 5.6 cubic feet. The stock box with horns removed is 3.5 cubic feet--sooo... space taken up by the woofers/passive radiator/crossbraces I'm down to around 3 cubic feet.
The woofers were 4 ohms and rated 300 watts, the amp is rated 600 watts RMS so I'd need two woofers in series to handle the amp. Then I remembered Isobarik alignment--my stock box would work, I can use two woofers for 8 ohms and power handling. Sure, I lost 3 dB over one woofer but they are rated at 95dB and the 3dB I get back with double the power handling.
It has a completely different bass response and sound. The original tuning was a vented cab at 40Hz--now it is a PR cab isobarik tuned to 22 Hz. The old cab was LOUD (it is a PA box) the new cab is not as loud but goes an octave lower, it sounds "sealed" with music and when the PR gets jumping below 30Hz--the house shaking HT sub shows up.
A female friend of my wife was over and commented on how well the sound system sounded. She spotted the grey carpeted box off in the corner and asked what it was..told her the subwoofer. She said it was the first one she ever heard that didn't sound like a boom boom boom box--sounded very nice--smooth, accurate (she is a pianist) She hung out listening to classical, rock and some rap/R&B and liked the sound.
I would say the sound is a mix of the distortion reducing push/pull isobarik and the very low tuning of the PR to drive down the group delay to below perception.
Would I purposely go out and buy two woofers and build an isobarik? Yes if the box had to be really small, the woofers could handle a lot of power and it needed to go deep. The oddest isobarik I've ever seen had 4 woofers in a bandpass enclosure in a car. It was very small but could handle a ton of power, sounded good (for a bandpass) and MOST importantly--was 3 times smaller than the original box. The guy got married and learned what WAF means.
The second isobarik sub is sitting in my living room. Had a pair of Cerwin Vega V15E PA speakers in really nice 3/4" ply boxes with blown midranges. Found the specs on the woofers--calculated the correct box size at around 5.6 cubic feet. The stock box with horns removed is 3.5 cubic feet--sooo... space taken up by the woofers/passive radiator/crossbraces I'm down to around 3 cubic feet.
The woofers were 4 ohms and rated 300 watts, the amp is rated 600 watts RMS so I'd need two woofers in series to handle the amp. Then I remembered Isobarik alignment--my stock box would work, I can use two woofers for 8 ohms and power handling. Sure, I lost 3 dB over one woofer but they are rated at 95dB and the 3dB I get back with double the power handling.
It has a completely different bass response and sound. The original tuning was a vented cab at 40Hz--now it is a PR cab isobarik tuned to 22 Hz. The old cab was LOUD (it is a PA box) the new cab is not as loud but goes an octave lower, it sounds "sealed" with music and when the PR gets jumping below 30Hz--the house shaking HT sub shows up.
A female friend of my wife was over and commented on how well the sound system sounded. She spotted the grey carpeted box off in the corner and asked what it was..told her the subwoofer. She said it was the first one she ever heard that didn't sound like a boom boom boom box--sounded very nice--smooth, accurate (she is a pianist) She hung out listening to classical, rock and some rap/R&B and liked the sound.
I would say the sound is a mix of the distortion reducing push/pull isobarik and the very low tuning of the PR to drive down the group delay to below perception.
Would I purposely go out and buy two woofers and build an isobarik? Yes if the box had to be really small, the woofers could handle a lot of power and it needed to go deep. The oddest isobarik I've ever seen had 4 woofers in a bandpass enclosure in a car. It was very small but could handle a ton of power, sounded good (for a bandpass) and MOST importantly--was 3 times smaller than the original box. The guy got married and learned what WAF means.
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