Bose 901 upgrade

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Bose 901 upgrade

Working all my life in hi fi and professional audio a few years ago I wondered what would happen if I replaced the internal wiring of a pair of 901’s for far better-quality wires. So, I bought myself a set of Bose 901 series 3 with the original equalizer. I allready had good results listening to 16 awg multi stranded silver plated speakercable; van den Hull snowline. So, I removed all the wire wrap cables and soldered the new cable from driver to driver. Use a 75-watt soldering iron minimum since the silver-plated cable draws a lot of heat away. And don’t be afraid to drill an extra hole to route the new wire from one chamber tot the other. Finally, I replaced the speaker connections for gold plated 4 mm female banana jacks.

I also upgraded the equalizer. In the signal path there are 3 10uf electrolytic capacitors in each channel. I replaced them for 10uf MKP. And also replaced all the transistors for new ones.

I can say that the difference in sound reproduction is very big; or to say it better; dramatic. The low end and high end is much better. The dynamic range is much better. The date code on the drivers is 1979; it is unbelievable what these 901’s can do! I am using a 100 watt amplifier and I am listening to high res audio via Qobuz. And I am using a USB to USB audio isolator to connect my PC to my DAC; I bought one via aliexpress for a few euro's.

I was searching online if somebody else had done this before, but I did not find anything sofar. So, I am very curious for anybody who will also perform this upgrade and tell me what you hear!
Changing Electrolytic caps to MKP can make a significant difference.


 
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diyAudio Chief Moderator
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No doubt about it.
They are also the reason we don't have them on the regular market.
They also had a pro sound cabinet the 802 which I have heard in theater installations and they were better than many back in the day. Especially in vocals.
bose-panaray-802.jpg
 
diyAudio Chief Moderator
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They were fun speakers the 901s. Not monitors but good fun. The pro ones had eight units, only forward firing. 120x100 dispersion. Small speakers with horns were usually bad phased smack in the middle so bass and treble lifted crossoverless extended rangers were more ineligible in small venues, theatrical stages, and houses of worship.
 
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This reads poorly. I was trying to say they came and went for a reason. If they did what was advertised, they would still be on the market and emulated.
I'm confused. Are you referring to 802 or 901? The 802 was produced for at least 3+ decades (3 series) and the 901 (6 series) for 5 decades. Bose is highly litigative and those designs were covered by a variety of patents issued over their lives. Bose defended its patents and product designs vigorously, copies if they existed were short lived. (There were clones) Many 802 are still in active use with sound reinforcement companies throughout the U.S. and Europe, and I would guess Canada as well. While I am not terribly proud to admit it I was a long time Bose employee - noting that I left late in 1999 to restart my ill-fated high end audio electronics business.

My first experience of relatively high performance audio in a home environment was a pair of Bose 901 Series I with a large Kenwood receiver in 1975.

Something else to note is the large changes at Bose over the past couple of decades, Dr. Bose died some years ago, his son was not interested in taking over, and today the company is wholly owned by Massachusetts Institute of Technology. (MIT) The original management has all aged out, it's a very different place from the days I worked there.
 
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Kevin, I am glad you shared your experience with the members. Us backroom boys are very familiar of course but it's good to have everyone else in the loop.

I was referring to the 901's. I remember the great fanfare that came with them. I was only 6 when they were introduced but already a music fan because of my older brother.
The 901 aka flagship of Bose came with an unlimited wattage rating. They spoke of the stage presence and all sorts of things. My only point was that if they were all they were made out to be, they would still be around. So would the 2201.
The 802 was perfect for what it was intended. Compact, not that bad sounding and could take a beating. Yes, there are still some pubs with them but the numbers are dwindling for sure.
 
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Tony EE
Your taunts fall on deaf ears - I'll build what I feel like building...

It's ironic that you claim to have deaf ears when you are in a DIYAudio web site.

Hah!

I shake my ADS L810s in your general direction! Yep, I had them rebuilt too... one of the woofers needed a new coil/spyder. And of course caps. But I won't risk the Maggies, or the AEs, or the Elacs, or the Quads, or the PSBs, or the Missions, or the..... hmmm.... I only got 11 pair of speakers... surely I need more!
 
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They also had a pro sound cabinet the 802 which I have heard in theater installations and they were better than many back in the day. Especially in vocals.
View attachment 1195509

Back in the early 80s I used Bose PA systems for live bluegrass shows.

They actually sounded very good. Mixed 12 channels into two ( vocals, instruments ) for the main audience PA.
 
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Do you guys remember a blue cone era 4.5" driver in water at shows? I think I vaguely recall such a thing in a very old show. Was ever a water resistant version?
Yes, there were waterproof 4.5" drivers, they were used in some 100 (101/102?) series full range speakers, the model I am thinking of particularly was intended for under eve, marine and near pool use. I remember going into the test chamber to do my own life tests and seeing them in buckets of water, and saline solution playing away - it was an intriguing thing to see, but the noise levels even with protective gear was such that you did not want to spend more time than necessary in that space.

My response to Cal's comment (and I am no fan of 901 either btw) is that I cannot think of another speaker other than the Klipschhorn that was in continuous production for 50 years - the world changed drastically over that time and the target audience was never really audiophiles, the people buying those speakers would today perhaps be the upscale home theater crowd - they also require a fairly large space to perform their best. Interestingly they were designed primarily with classical music reproduction in mind.

The 2201 dates from the dawn of Bose history and I think only something like a dozen pairs were ever built and sold in the year or two before the 901 arrived in 1968. They were hand built by a small group of the founding engineers and technicians to the best of my recollection. They were also extremely expensive for the time and were intended mainly as a proof of concept for some acoustical theories Dr. Bose was investigating. Sherwin Greenblat was the project engineer at Bose who developed the 901 released in 1968, he later became President and CEO of Bose during the entire the time I was there. T
 
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Tony EE
Your taunts fall on deaf ears - I'll build what I feel like building...
Indeed, to paraphrase Johnny Darko; it’s nobody’s job to tell someone else how to spend their disposable income/time.
That said, I’ll reluctantly add my vote to the “sure, I guess you could, but why?” column. My most memorable experience with the 901s back in the late ‘70s was that they made for an effective and reasonably portable PA for girls’ high school dance music; two pairs driven by Crown IC150/D 300A. IIRC source was a Thorens TD125 / SME3009 / Stanton cartridge. Did that only once. Yup, they played loud enough, but anyone familiar with the IC150 is probably shuddering at how they would have sounded.