Thank you Marco for posting these plots. I had these and others on one of my storage devices. Unfortunately, I lost about 250GB of audio related data earlier this year due to an "external factor". Actually, it was 300GB, but had 50GB backed up.
As for the HF1440, it's been more than 1.5 years since the driver was first announced. Someone I know had pre-ordered the driver, until September when he gave up.
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Regarding MJ Audio Technology's credibility, here's what diyaudio member tiefbassuebertr has to say:
“This magazine, founded in 1924 by Mr. Mitsugu Tomabeji, is one of the earliest and most influential radio magazines that I know. In the early years it was Radio experimenter’s magazine (Musen to Jikken = Radio and Experiments). The early publisher of this magazine was the currently brand ITO and the currently publisher now is Mr. Seibundo Shinkosha. In general this magazine is a DIYer magazine and is very technical but is full of great articles on electronics and speaker design, room acoustics, audio history, as well as reviews, news, show reports, etc.”
“This magazine, founded in 1924 by Mr. Mitsugu Tomabeji, is one of the earliest and most influential radio magazines that I know. In the early years it was Radio experimenter’s magazine (Musen to Jikken = Radio and Experiments). The early publisher of this magazine was the currently brand ITO and the currently publisher now is Mr. Seibundo Shinkosha. In general this magazine is a DIYer magazine and is very technical but is full of great articles on electronics and speaker design, room acoustics, audio history, as well as reviews, news, show reports, etc.”
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Interesting comment on manifold drivers that were discussed previously:
"With regard to manifolding -
Multiple drivers on the same horn require some sort of apparatus (manifold) to get them mounted up.
Early WE attempts were clumsy - I remember seeing some of them. Straight pipes screwed into threaded hole bored into a plate mounted to the throat of the horn.
Not very good - LOUD, but didn't sound good.
WE then changed over to the multiple-driver throats most here are probably familiar with, which worked pretty well.
Jensen and Magnavox, along with Harry F. Olson at RCA, all tried different approaches - some worked better than others.
The kicker is getting the waveforms to arrive in phase and combine, rather than subtract from the total SPL - in addition, out-of-phase signals sound pretty nasty.
EV tried manifolding several years ago - their "MT" series was heavily promoted and quite popular for a while. Their big problem was they forgot (if they ever knew) that you don't bend high frequencies around corners - especially at 90-degrees - and they had serious sound quality issues.
Jerry K. Hubbard, then Head of Acoustics at Altec Lansing, solved this problem - he divided the vertical diffraction slot on the MANTARAY horn throat into two parts: upper and lower. He then fed each half into the horn in a gentle, sloping manner. This eliminates the problem right angled manifolds had, and resulted in an overall increase of SPL of 4dB, instead of the theoretical 3 dB!
Sadly, this method only works with horns with straight vertical diffraction slots, like the MANTARAY, but it works REALLY WELL!"
"With regard to manifolding -
Multiple drivers on the same horn require some sort of apparatus (manifold) to get them mounted up.
Early WE attempts were clumsy - I remember seeing some of them. Straight pipes screwed into threaded hole bored into a plate mounted to the throat of the horn.
Not very good - LOUD, but didn't sound good.
WE then changed over to the multiple-driver throats most here are probably familiar with, which worked pretty well.
Jensen and Magnavox, along with Harry F. Olson at RCA, all tried different approaches - some worked better than others.
The kicker is getting the waveforms to arrive in phase and combine, rather than subtract from the total SPL - in addition, out-of-phase signals sound pretty nasty.
EV tried manifolding several years ago - their "MT" series was heavily promoted and quite popular for a while. Their big problem was they forgot (if they ever knew) that you don't bend high frequencies around corners - especially at 90-degrees - and they had serious sound quality issues.
Jerry K. Hubbard, then Head of Acoustics at Altec Lansing, solved this problem - he divided the vertical diffraction slot on the MANTARAY horn throat into two parts: upper and lower. He then fed each half into the horn in a gentle, sloping manner. This eliminates the problem right angled manifolds had, and resulted in an overall increase of SPL of 4dB, instead of the theoretical 3 dB!
Sadly, this method only works with horns with straight vertical diffraction slots, like the MANTARAY, but it works REALLY WELL!"
The theoretical increase in level desired in manifolding drivers is 6dB, 3dB from doubling Sd, plus 3dB for doubling power.
Who was it you were quoting?
Rectification, the quote was from Todd W. White (Owner & Webmaster Altec Lansing's (unofficial) Homepage).
Since it is quiet here, I drop some proper dual manifold horn porn.
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Someone one once suggested a place online to get all my wood from, as well as, have them cut to order....I don't know if I can find it again in the thread....otherwise I think its time to see who can cut my wood for me in my area.
B&C DCM50 converted to field-coil by Wolf von Langa.
A flange was made to attach the drivers to the Altec dual throat adapter.
A flange was made to attach the drivers to the Altec dual throat adapter.
Sorry, but i'm a technical redactor since 20 years and i'm bored to read that my work is porn... i'm not a pornograph.
My wife hates it if someone refers to a car as sexy. I understand.
Now let's get back to the scheduled program.....
Now let's get back to the scheduled program.....