FYI tomtt, the flaw in those drivers is/was the braided leads from the solder tabs to the cone. The cone side is set with what looks like bituminous. They will stress crack after a bit. Making the sound stop or crackle. So, they need to be replaced with a modern wire. I replaced a whole bunch of them.
They're a great sounding little driver, I'd suggest using a few in a small enclosure, or even in some sort of TQWT type of thingie... or a little line array of 4/5 on a side.
Worthy drivers!
They're a great sounding little driver, I'd suggest using a few in a small enclosure, or even in some sort of TQWT type of thingie... or a little line array of 4/5 on a side.
Worthy drivers!
Igor: "The tweeters have arrived, Master!"
Me (Dr. Bosenstein): "Excellent! Prepare for soldering!"
Not having access to Nature's lightning (it's clear and sunny here in FL in the winter), I will have to make do with the loathsome NU3000 amp. I made cables (Neutrik) for it and soldered each tweeter to a long run of cable. No enclosures ("yet"). I hooked up the spare MiniDSP and configured the tweeters with a high-pass 12 dB/oct L-R at 5000 Hz (I think). I can of course hear a difference. Now comes the fun part...to integrate the tweets with the "woofers" (901's). Suggestions for x-over settings? I don't have the time, right now, to do much measurements but equipment is on hand. If I wasn't clear, I now have 4x 901 II running "full range" off a NU3000; now I've added a tweeter per channel powered by a 2nd NU3000 with its own MiniDSP so that tweeter only gets the high notes
Me (Dr. Bosenstein): "Excellent! Prepare for soldering!"
Not having access to Nature's lightning (it's clear and sunny here in FL in the winter), I will have to make do with the loathsome NU3000 amp. I made cables (Neutrik) for it and soldered each tweeter to a long run of cable. No enclosures ("yet"). I hooked up the spare MiniDSP and configured the tweeters with a high-pass 12 dB/oct L-R at 5000 Hz (I think). I can of course hear a difference. Now comes the fun part...to integrate the tweets with the "woofers" (901's). Suggestions for x-over settings? I don't have the time, right now, to do much measurements but equipment is on hand. If I wasn't clear, I now have 4x 901 II running "full range" off a NU3000; now I've added a tweeter per channel powered by a 2nd NU3000 with its own MiniDSP so that tweeter only gets the high notes
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If the 901 equalizer provides a 2.2dB bost for the series I and 4dB's for the series II @5KHz, I would think that 5 KHz is nota bad starting point (see links of post #36.)
Bose 901 SPL/1W higher than 90dB. Selenium ST200 about 105/110 dB (1 W / 1 m). So I assume you need 10 or 15dB attenuation on the tweeter.
Bose 901 SPL/1W higher than 90dB. Selenium ST200 about 105/110 dB (1 W / 1 m). So I assume you need 10 or 15dB attenuation on the tweeter.
coming alone fine ...
Based on some REW measurements from last Spring, the in room response (3 samples) of my Bose 901 with NO EQUALIZATION peaks very close to 6.8 KHz. From there the drop-off is very close to 12 dB/Octave (11.2 to be more precise.) The "-3 dB" power point seems to be about 8.4KHz. So I am using that as the crossover point for the new tweeters. All my adjustments so far are "by ear". Right now the 901s are not getting anything much higher than 8 KHz (by DEQ2496's GEQ, not a MiniDSP). For making the "woofers" and the tweeters similar in volume, I am using pink noise near the x-over frequency, and try to match each by ear to similar loudness.
Based on some REW measurements from last Spring, the in room response (3 samples) of my Bose 901 with NO EQUALIZATION peaks very close to 6.8 KHz. From there the drop-off is very close to 12 dB/Octave (11.2 to be more precise.) The "-3 dB" power point seems to be about 8.4KHz. So I am using that as the crossover point for the new tweeters. All my adjustments so far are "by ear". Right now the 901s are not getting anything much higher than 8 KHz (by DEQ2496's GEQ, not a MiniDSP). For making the "woofers" and the tweeters similar in volume, I am using pink noise near the x-over frequency, and try to match each by ear to similar loudness.
I can't resist. The only good sound that ever came from a 901 was the crunch of a truck driving over them. Seriously, the 301 was a better speaker! The basic premise the 901 just plain did not work. Instead of some magic all around sound you got a vague mushy un-localized honky mess.
Now to have some fun: Take everything out. Cut a hole in the from big enough to insert a decent modern mini monitor. Put the grill cloth back over it. A bit of NeverDull on the pedestals and you are in business.
Yes, but it is vague mushy un-localized honky mess stereo everywhere, not just in the sour spot 
I don't know about "better" but I agree the 301 were very good, and also I liked the original 501 (with 4 tweets per). Did not own these, but lived with those who did. Say what you will about the 901, but any speaker that has sold for nearly 50 years (granted, with some substantial design changes) must be pleasing someone, not just the corporation. For poor DIY experimenters like me, we can buy them used, and sell them used
I don't know about "better" but I agree the 301 were very good, and also I liked the original 501 (with 4 tweets per). Did not own these, but lived with those who did. Say what you will about the 901, but any speaker that has sold for nearly 50 years (granted, with some substantial design changes) must be pleasing someone, not just the corporation. For poor DIY experimenters like me, we can buy them used, and sell them used
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Current Ebay sales
Not sure how long these links will be valid, but here is two examples of DIY Bose901 type speakers:
Bose 901 Speaker Kit | eBay
Bose 901 Style Speakers Custom Made with Matching Wooden Stands | eBay
Disclaimer: I have no commercial interest in either listing. The "kit" listing is interesting but I think the drivers listed are not the true Bose originals.
Not sure how long these links will be valid, but here is two examples of DIY Bose901 type speakers:
Bose 901 Speaker Kit | eBay
Bose 901 Style Speakers Custom Made with Matching Wooden Stands | eBay
Disclaimer: I have no commercial interest in either listing. The "kit" listing is interesting but I think the drivers listed are not the true Bose originals.
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