My impressions of the 901

[Guest tony3d]

It's really a good feeling to be on a thread with people that actually appreciate the sound of these speakers. Hi, Thought I should share with you my own experiences with the 901. My first introduction to them was back with the series 1's. I heard them at a friends house who happened to be an engineer at Fermi National Accelerator Labs. This guy was an absolute perfectionist when it came to his audio system. He wasn't satisfied with the low end of any speaker he heard at the time. Remember we are talking 1970. So he built his own speakers using Electro-voice 30" woofers!. He built a ported enclosure, using the crawl space under his house to get the required cabinet volume behind the speaker so he could tune the port based on the free air resonance of the woofers. He finally finished the project 3 months later. The first time I heard it I was floored! He powered them with a Crown DC300 amp. One day I get a call from him and he told me to get over right away. He sits me down in front of these 2 weird looking boxes he had suspended from his ceiling and said, "well I finally found them". He put on a cut from the Missing Link direct disc and my jaw dropped. The low end just blew away his 30" masterpiece's which he promptly removed shortly after. From that day on I was after those 901's. 

At the time I worked for Jensen Sound labs curve tracing speakers. I have to laugh when I hear these Bose bashers on all these websites rant on about things they know very little about. A lot of them say that Jensen made the drivers for the 901 series 1 and 2. Not quite right. Rola made the drivers for Bose in those days who also made the drivers for Jensen. Jensen stopped manufacturing drivers many years before that. Rola manufactured drivers for many other prominent speaker companies of the day. The 901 series 1 and 2 were an excellent speaker in there day, but had real difficulty reaching down below 50 hz with out severe doubling at high listening levels. They were also very inefficient. The series 3 was a new rebirth for the 901's. Those so called cheap, junky, toy like drivers are actually extremely high quality transducers! The advent of the helically wound voice coils and oh yes those plastic baskets brought the 901 drivers into a whole new level of precision. Everybody rants on about the cheap plastic baskets, but do they realize that is the only way that Bose could hold the very tight tolerances required for that driver in order to raise the system's overall efficiency. You can mold plastic to much tighter tolerances than a stamped metal basket could hope to hold. I know this is true because I was a machinist for 25 years. It is stronger, and much less resonant than a stamped basket. When I use to curve trace Jensen drivers you could feel that metal basket flexing all over the place. This brings us to the cheap plastic matrix enclosure. Bose was brilliant making that out of plastic. Again, almost resonant free, and plastic gave them the opportunity to make a very complex chamber to route the air flow, benefiting both efficiency, and low end performance. Just put your hand on the 901 cabinet while pushing 50-60 hz and tell me what you feel. I'll admit that the ports are not totally silent, but the only time I can here them at all is when I'm driving 250 watts peak power into them on pipe organ music, and then only on the very lowest notes! So the ports actually do a great job raising the efficiency of the speaker while re-enforcing the low end to bring the range down to about a clean 35 hz! There is plenty of output that low. 

Back to those cheap drivers that can't reproduce bass very well. The 901 can move enormous amounts of air, and because of the matrix enclosure there movement has been greatly reduced thus reducing the distortion from the very large excursions of the previous non ported systems. By using the 9 cones back wave to re-enforce the forward motion of the drivers, Bose doubled there bass output. Setup properly and given enough clean power, the 901's are capable of very impressive tight clean bass output. And I'll tell you, these speakers will put a 400 watt amp to bed before running out of clean undistorted sound. The 901's are not the finest sounding speakers on the market, but they are certainly among them. So many people bash this speaker, and say some of the most ridiculous things about them, that quite frankly I'm embarrassed for them. They are an embarrassment to any board and the community. 

Remember that engineer friend from Fermi Labs. He could go on with more facts about what Bose did right with the 901's than you or the Bose bashers would care to listen to. He just sold his 901 series 1 for the series 6 about a year ago. He sees no reason to look any further. Currently I own a Pair of 901's series 6 speakers driven with a 475 watt per channel Crown Xti-2000 power amp. There are many good worthwhile improvements in the 901's. Just remember to set them up properly and feed them as much clean power as you like there practically indestructible! How many people can say that about there speakers? Must be those cheap plastic drivers. Well there is my take on it. I am in no way affiliated with Bose. These are purely my opinions. One more interesting tidbit. The bass reflects enclosure principles that the 901's are based on was invented by Wayne Schott of Prospect Il. It became popular after a white paper was published on one such design by James Novak an engineer at Jensen Sound Labs. I knew him well.