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!
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!
They would still be 901's. Wires are far enough down the list of important things here that asking this question is close to immaterial. As a dedicated speakerholic, please don't put money where it is wasted. We are here for the music, not what you read in a book about what wire can do.
Welcome to the diyAudio Mike. There are some of the finest minds here and I have a feeling you will get to know a few in this thread. Don't take the advice personally or over seriously.
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Well no one will say you aren't a bundle of energy. I had series 1 in the 70s they were my wifes. There was no
doubt you could blast with those things. I just kept going back to my Jensen Imperials and Mac gear. I still have
that gear in storage.
I remember they use to plug 901 I into a 110v ac receptacle for a while, unplug and then play music through
them. It was a Bose sales pitch to show how VERY tough they were.
I know they could suck a big SS Mac amp dry. LOL
Small planars and ribbons have long since replaced all that for me. Hybrid LS and servo subs were my choice in
the early 80s. I never looked back. Strathearns, Neo planars etc. will outlast my grandkids and are still pretty
serviceable.
Rewiring for better sound in a 901? I bet they did sound better. Now wire in a ribbon tweeter that sets on top and
a sub that sets on the bottom. Minor tweaks! Just something Bose left out. 🙂
Regards
doubt you could blast with those things. I just kept going back to my Jensen Imperials and Mac gear. I still have
that gear in storage.
I remember they use to plug 901 I into a 110v ac receptacle for a while, unplug and then play music through
them. It was a Bose sales pitch to show how VERY tough they were.
I know they could suck a big SS Mac amp dry. LOL
Small planars and ribbons have long since replaced all that for me. Hybrid LS and servo subs were my choice in
the early 80s. I never looked back. Strathearns, Neo planars etc. will outlast my grandkids and are still pretty
serviceable.
Rewiring for better sound in a 901? I bet they did sound better. Now wire in a ribbon tweeter that sets on top and
a sub that sets on the bottom. Minor tweaks! Just something Bose left out. 🙂
Regards
I was going to suggest what Jimi Hendrix did to his guitar at Monterey as an improvement...
The 901 weren't completely rotten, unlike some of Bose's other products . Kudos to the OP for striving to improve them, although they really need more than 100 watts to wake up ( although series III and higher were easier to drive). I've had series II in the past and they were decent for filling a space with sound when set up right
I'm not sure how to respond here. For me, some things are best left, broken.
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Series I could make a BIG Mcintosh run out of gas. I also remember Bose and Mcintosh paired at Dealers.
Series I were 8 ohm in parallel 4 ohms. A lot of users mounted two high and 2 low.
LOUD comes to mind, and paired with a turntable they never pumped like a lot of speakers without a rumble filter.
Tough combo and you never blew a tweeter.
They still hadn't discovered BASS either. 70s Infinity had servo BASS columns. Pretty darn good.
Regards.
I don't think there is one. I've seen small planars play down to 200hz and up to 20khz. The more you use
when pushing lower FR the better. 2-8 drivers can really get loud. Full range drivers are kind of a myth.
Bi and Tri axle speakers could do it. A single 20-20 driver in open air.🤷♂️ for 20.00 usd. The perfect start
to a perfect driver.
The issue is they use the distance from the front and side walls to increase bass response. Those walls offer a
lot of distortion and time delay. Normally the corners are a place I put Helmholtz bass resonators, not
speakers. The front wall I use heavy floor to ceiling curtains. Closed or open, for a little livelier room.
It was the 70s, the 80s couldn't make up their mind between plastic and more plastic. Bose couldn't either.
I have a plan one day for mounting a bunch of the aluminum cone MCM drivers in a hexagonal prism box. Since the QTS for those drivers is poised between ported or sealed, I might do either - maybe a combination of down-firing port and slot loading. For HF duty, I have some of the Tang Band 2" extended range drivers that Apex Surplus was selling for a while. The HF drivers would go into their own well-stuffed sealed chambers to keep them from being horsed around by the MCMs....
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I'm not married, but I think I'll have them sit on the carpet - I'll be scattering the drivers over several faces of the hexagons for semi-omni behavior. I built a pair of speakers like this in 1978-79 with sixteen 5" "Westwell" drivers from Mc Gee Radio, but the boxes were too small for serious bass. I intend to correct that fault this time around.
Wit something like 20db boost at 25hz they could eat any amp 9 series connected 1 ohm speakers, wire won't make any difference.
Recapping the eq box and upgrading the op amps will make a huge difference.
Recapping the eq box and upgrading the op amps will make a huge difference.
Here's graphs of my 901-1 outdoors sans EQ plus graph of the EQ box's settings
The 901's used active EQ to force frequencies out of drivers that weren't designed for it !
Depending on your amp, just imagine what that does to your headroom.
Depending on your amp, just imagine what that does to your headroom.
While "full rang" drivers are a myth, a bunch of full range drivers can "emulate" full range behavior by severe use (abuse?) of bass and/or treble boost .
The same trick is employed by line arrays using tiny full rangers, subwoofers employing linkwitz transforms etc ... though rarely in the absurd amounts employed by the 901 . All said and done, the 901 only deserves about 30 % of the ire directed at it 🙂
The same trick is employed by line arrays using tiny full rangers, subwoofers employing linkwitz transforms etc ... though rarely in the absurd amounts employed by the 901 . All said and done, the 901 only deserves about 30 % of the ire directed at it 🙂
How about using a design based on the Cone Of Silence.
Put the speakers on the outer shell, pushing in, stick your head in and crank it.
Of course, you might need ear plugs and smoking a cigarette will present a more cohesive sound field.
Truly ahead of their time, they even had a Portable Cone Of Silence... hook it up to your portable audio and off you go..
How about building a regular dodecahedron and putting speakers on its faces?
https://mathworld.wolfram.com/RegularDodecahedron.html
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