Phase probably not as important as it would be for a single point source full range driver. I was just trying to see how to get better SQ from the miniDSP EQ approach that Zobsky said he tried and found the analog EQ in the Bose box better. I am not sure why that should be the case? Maybe the ADC/DAC in the minDSP is not as good as the all analog EQ? Even with direct reflecting speakers, if you excessively EQ a speaker, there is a distinct 'phasiness' sound that is just plain bothersome if you can hear it.
Wednesday's pontifications...
Hi xrk: I've discussed using the MiniDSP as a 901 EQ elsewhere, including made a tutorial for the Co.'s web site (using REW to make a custom curve.) I'll admit that I rarely used the Bose EQ units. Not because they didn't work or even sound bad (itself a good feat for forty year old electronic box.) No, I was won over to the dark side of room EQ ever since the DEQ2496. I am satisfied with the sound through the after market EQ.
It would be informative to have a more thorough test of one or more real Bose units vs. a replica EQ via a 21-st century box
We already have that, how about more data? I dusted off my Ethan Winer book and he is pretty dismissive of claims that phase differences (in electronics) are audible.
Hi xrk: I've discussed using the MiniDSP as a 901 EQ elsewhere, including made a tutorial for the Co.'s web site (using REW to make a custom curve.) I'll admit that I rarely used the Bose EQ units. Not because they didn't work or even sound bad (itself a good feat for forty year old electronic box.) No, I was won over to the dark side of room EQ ever since the DEQ2496. I am satisfied with the sound through the after market EQ.
It would be informative to have a more thorough test of one or more real Bose units vs. a replica EQ via a 21-st century box
We already have that, how about more data? I dusted off my Ethan Winer book and he is pretty dismissive of claims that phase differences (in electronics) are audible.
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A drive unit that might work.
SB Acoustics :: 4? SB12NRX25-4
I was speculating about 9 off these in an enlarged version . It doesn't bottom easily so will accept EQ .
Eminence Beta-12LTA 12" Full-Range/PA Driver
SB Acoustics :: 4? SB12NRX25-4
I was speculating about 9 off these in an enlarged version . It doesn't bottom easily so will accept EQ .
Eminence Beta-12LTA 12" Full-Range/PA Driver
sometimes. I understand completely. I love 901's and have built an OB speaker using 12Lta around similar engineering requirements . My Pro Audio friends helped me get it right . Then it hit me, the 901 was looking for something like 12Lta if it was to impressed the Pro Audio guys . Bose seems to have upset them as in Pro Audio applications Bose were being dismissive of the existing industry . They said too forcefully they were better . Grudgingly my friend John says they are good mid-ranges . For hi fi at sensible levels they will work with EQ . Then it hit me , if size is not too critical 9 x 12 Lta might work . Hummer version .
I like this idea of excess in paying homage to what may perhaps be Amar Bose's finest achievement.
Although I am not sure the 12LTA is the way to go because of its Qts and Vas parameters - tend to make its cabinets huge, even for a single driver let alone x9. The size would just be impossible to fit together in a box that has the same proportions as the 901. I think you want something with lower Qts and more xmax and then let the EQ do its magic to eek out the bass and top end.
I am thinking of a PA driver that has a fairly wide range but not necessarily full range. Take care of that with several drivers that have HF capability via CD-horns in a coax: use qnty 9 x B&C 12CXT with CD coax horns to give the wide band sound stage and 98 dB efficiency. The Qts is lower so the box will be more compact relative to 12LTA. I would bi-amp and run DSP XO's and EQ of course.
Wiring 9 drivers in series - parallel gives 8 ohms nominal so that works well and the efficiency is going to be +9dB? if I did the math right that will be 107dB at 1 meter and 2.83v. The cone area is equivalent of qnty 4 x 18 in drivers so this puppy will move a lot of air and the bass will be incredible.
It will be pretty expensive but to be expected for an over the top Hummer of a speaker.
Although I am not sure the 12LTA is the way to go because of its Qts and Vas parameters - tend to make its cabinets huge, even for a single driver let alone x9. The size would just be impossible to fit together in a box that has the same proportions as the 901. I think you want something with lower Qts and more xmax and then let the EQ do its magic to eek out the bass and top end.
I am thinking of a PA driver that has a fairly wide range but not necessarily full range. Take care of that with several drivers that have HF capability via CD-horns in a coax: use qnty 9 x B&C 12CXT with CD coax horns to give the wide band sound stage and 98 dB efficiency. The Qts is lower so the box will be more compact relative to 12LTA. I would bi-amp and run DSP XO's and EQ of course.
Wiring 9 drivers in series - parallel gives 8 ohms nominal so that works well and the efficiency is going to be +9dB? if I did the math right that will be 107dB at 1 meter and 2.83v. The cone area is equivalent of qnty 4 x 18 in drivers so this puppy will move a lot of air and the bass will be incredible.
It will be pretty expensive but to be expected for an over the top Hummer of a speaker.
If you look at SB 4 inch it is a full range in the sense of the Bose way . It truth the Bose never really was a full range unit and the Pro World thought it a money making exercise using mid range units . The truth is somewhere between the two .
12Lta is almost exactly as the Bose was . That is with a bit of EQ reaching 14 kHz and better than 35 Hz . My tests of 12 Lta show the wizzer to be better than many dedicated midranges if passive EQ . That is if fed from low Z they behave well . What is lost in the crude device is won back by not having an electrical crossover .
I was in Bonn Germany in 1982 . I saw a very beautiful and excellently proportioned lady walking down the street towards me ( she didn't need Dow Corning ) . To my amazement I got the glad eye in return . Then it became clear . She was 7 feet tall . I should have noticed her related to the street furniture . She was my super Bose as a woman . I am 6 foot 2 . I would have been intimidated . Hey Ho as we Brits say . The worst of it is she looked to be a very nice person and what a fool not offer to buy her a coffee .
12Lta is almost exactly as the Bose was . That is with a bit of EQ reaching 14 kHz and better than 35 Hz . My tests of 12 Lta show the wizzer to be better than many dedicated midranges if passive EQ . That is if fed from low Z they behave well . What is lost in the crude device is won back by not having an electrical crossover .
I was in Bonn Germany in 1982 . I saw a very beautiful and excellently proportioned lady walking down the street towards me ( she didn't need Dow Corning ) . To my amazement I got the glad eye in return . Then it became clear . She was 7 feet tall . I should have noticed her related to the street furniture . She was my super Bose as a woman . I am 6 foot 2 . I would have been intimidated . Hey Ho as we Brits say . The worst of it is she looked to be a very nice person and what a fool not offer to buy her a coffee .
(warning - tongue in cheek)
That is why they are labelled BOSE (Buy Other Sound Equipment).
Peace!
I wonder why I haven't seen a DIY of the 901 using some high quality but inexpensive full range drivers? I think it might work out very well especially with something like Vifa TC9FD. With a minDSP to do the EQ and a simple foam core enclosure one can quickly build a 901 that has drivers truly capable of hitting 18khz and as low as 50 Hz. Visaton FR10's or Faital Pro 4FE35's may work too. Hmm...
Something tells me that an XXL version of Bose 901 using 9 Lta 12 drivers or similar, driven by 1.5w tube amp, wouldn't sound that bad The main problem would be to get them in the house (and that is purely physical...regardless of WAF). But then, I think that most extraordinary creations came because someone said "Why not" and just did it
The main problem would be to get them in the house (and that is purely physical...regardless of WAF). But then, I think that most extraordinary creations came because someone said "Why not" and just did it Just so you know 12Lta is a wonderful sounding device . It does need low output impedance amps so might favour Dynaco etc. High Z makes it shout. Shame as voice quality is exceptional , it should be mediocre if looks meant a thing. Using an old Quad 303 suits it fine. Quad is old school excellent that suits old school excellent if 12Lta. I suspect the 12Lta equals the old Goodmans Axiom that go for silly money.
I guess the Bose is a sideways line array? I like dipole speakers . Bose might be saying the mistrusted bit is in fact the advantage.
12Lta made in USA. It must be the last hope saloon for quality low cost country of origin designs? Actually cheaper in UK!
I would vote for Heath EL 84 tube amp also. Leak TL15 plus ( not with KT66 ) with 84's also.
I guess the Bose is a sideways line array? I like dipole speakers . Bose might be saying the mistrusted bit is in fact the advantage.
12Lta made in USA. It must be the last hope saloon for quality low cost country of origin designs? Actually cheaper in UK!
I would vote for Heath EL 84 tube amp also. Leak TL15 plus ( not with KT66 ) with 84's also.
Hi xrk971,
Post #75: "... why I haven't seen a DIY of the 901..."
Maybe because the main interest in the Bose 901s was in the early 1970s? I build a set in 1974(?) using a 4-1/2" 8 Ohm fullrange sold by McGee Radio, Kansas city, MO. I made the boxes a bit larger (about 50% more volume), and we compared them to the original 901s. The copies had a bit more low frequency extension, but, just like the originals, they sounded better with the equalizer.
The little Vifas should sound great in this application. They would make for nice HT speakers, but careful consideration has to be given to the room.
Hope you'll build a foam core test set, and let us know what you find.
Regards,
Post #75: "... why I haven't seen a DIY of the 901..."
Maybe because the main interest in the Bose 901s was in the early 1970s? I build a set in 1974(?) using a 4-1/2" 8 Ohm fullrange sold by McGee Radio, Kansas city, MO. I made the boxes a bit larger (about 50% more volume), and we compared them to the original 901s. The copies had a bit more low frequency extension, but, just like the originals, they sounded better with the equalizer.
The little Vifas should sound great in this application. They would make for nice HT speakers, but careful consideration has to be given to the room.
Hope you'll build a foam core test set, and let us know what you find.
Regards,
in reply to why no DIY 901 activity, may I also point out the real thing is available cheap on Ebay and elsewhere. I just bought a working pair of Series II for $125. If I'd paid shipping it still would have been < $200. This is unusually good; sane prices (that is, what people actually pay), you can get working pairs of these older ones (I, II) for up to $300 or a bit more. Having a few bad drivers is average but they are very easy to repair and rewire. I have become something of an authority as I currently own four pairs
Why would you DIY except of course for the pride in making something superior? But almost for sure it won't be a good use of money.
Sent from Tapatalk app on my Android tablet.
Why would you DIY except of course for the pride in making something superior? But almost for sure it won't be a good use of money.
Sent from Tapatalk app on my Android tablet.
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