Bose 901-III speaker driver replacement to cure speaker foam "rot". Also applies to other Bose 901 speaker series. Resource links provided at end of video. Hope you find it helpful!
What a NEAT set of speakers! I love vintage Bose stuff! I grew up looking at the woofer in my Dad's 301's, and getting yelled at for pushing the dust cap in on the woofer :) I remember watching when he replaced the woofers from foam rot (this was probably 25 years ago). I THINK he tried a refoam, but I can't remember, but I do remember him installing new woofers. I want to find a pair for myself now and fix them up.
To each his own but in my opinion definitely should’ve took the time and repaired the original driver surrounds. Original Bose is the way to keep it and will sound better and hold its value.
The replacement speakers are probably better quality than the originals. Replacing the surroundings on a speaker is pretty time-consuming. No way I would want to replace eighteen of them, especially on a one-trick pony like the Bose 901. I had a pair in the 1970s and they sounded really good (If you took the time to place them in the room properly.) for Classical music and Folk music but lacked the highs and lows for Disco, Rock, Pop, Funk, and Country music.
The second cabinet on the bottom with no screws holding in the drivers might be a clone of a Bose 901. I worked for Bose from 184 to 2009. I do not remember ever seeing a 901 that did not have the traducers screwed into the cabinet. Very interseting for me. Thanks for posting.
Back in 1989, Bose replaced my 901 with a new pair because of this issue. The 901s had lifetime warranty back in 1980 when I bought them, not sure if this is still true,
As I recall the speakers can be mounted two different ways depending on the cabinet design -- either screwed into place, or twist-locked into place. The twist-lock should simply be "untwisted". But that might be difficult if the gasket has hardened. Using screwdriver and hammer to gently untwist the speaker might help.
Ok for what its worth. I have had 3 pairs of these. IIIs and IVs. The Bose used a Computer to tune all of the HVC Drivers to play exactly the same. Also the Bose speaker had Flat Wound Aluminum Voice Coils to produce the High Frequencies. Im curious to what kind of coils these have and if they were tuned or not. I never heard these played and you have to have the EQ to work to help with the frequencies to make these Cabinets come alive. You have possibly 6 years of life with this. Why not get the weather proof kits that go with the original instead of going this far to replace?
The "weather proof" kits that use a fabric surround will change the compliance of the original speaker drivers, and the free air resonance will also change. The fabric surrounds are not as stable under high excursion of the cones, so they 'pleat' and can produce self-noise or cracking over time. Newer speakers are now made with polyether foam surrounds (instead of polyester foam) and they tend to last longer than the original polyester foam surrounds which were more susceptible to dry rot. I suspect that with non-matching pairs of speakers like the owner has, these replacement drivers will go a long way to helping the speakers 'match' in sound. If it's possible to re-foam the original drivers, I still recommend that, but if there are damaged or missing drivers, or if they're in really bad condition, these 901 replacement drivers are probably just about as good.
Wrapped wires were a time-saving step on an assembly line. (This was before robotics became so common in factories.) There was a Dremel-looking device that hung from the ceiling that had a spool of wire threaded in it. It was a lot faster than soldering. Most likely it is a slightly inferior connection to a soldered connection.
I was very pleased with the replacement drivers from Parts Express. While it's certainly cheaper to replace the foam surrounds, it's much faster to simply replace the drivers. How old are your 901-V's? Surprised that the speaker surrounds have already deteriorated.
Not sure how old they are. I put new foam on them but at least 3 are rubbing voice coil or VC could be bad. I didn't use shims per video I watched. I have heard good reviews about the PE drivers but I also see some good original Bose drivers now for sale at about same price. Thanks for the video
Yeah, the rubbing voicecoil problem was one reason I didn't want to try just replacing the surrounds. Based on my research, the Parts Express drivers have the same specs as the original Bose drivers. They sound great again!
Parts Express drivers are possibly made in China and have copper voice coils, 901's have had since the 70's, helical voice coils, rectangular aluminum wire wound on its thin edge to tolerances of 0.001 inch by computer controlled machine. Also injection molded plastic basket/frame that does not distort magnetic field, etc. www.bose901.me
Bose 901 speakers have an 8-ohm impedance. Each internal driver has a 1-ohm impedance, but they are connected internally to provide an overall 8-ohm impedance to your amplifier.
You can still connect 4 ohm impedance up to a rated 8 ohm output source. Power factors will change. Impedance is kinda of like resistance but it doesn't follow the Ohm Law V=IR. Impedance for this circuit would follow the Induction formula of Z Sq = the Sq Root of R Squared + X of L squared. Z is Impedance. Z is reactance . A little more complicated. This because Inductance will lead Capacitive current by 90 degrees Thus the the impedance of an inductor or speaker in this case. Now XL, is the product of 2 times p (pi), or 6.28, the frequency of the ac current, in hertz, and the inductance of the coil, in henries. As you can see, Freq plays a large roll so Impedance really can change from micro second to micro second depending on the source. Playing Led Zeppelin or Taylor Swift? Lead Belly would be a lower number ; )
@@litzdog911 "Each internal driver has a 1-ohm impedance, but they are connected internally to provide an overall 8-ohm impedance to your amplifier." Wouldn't that be 9 Ohms since there are 9 speakers?
Unfortunately these are not they same drivers as the original. They will sound no where near as good as the genuine replacements. A lot of engineering went into the original drivers.
Not criticizing your decision to replace the drivers, but replacing the surrounds is not a difficult project. It's a little tedious, but very inexpensive.
The benefit of replacing the surrounds is you are assured the drivers are factory original Bose, made in Framingham, Mass. Of course the replacemant drivers from parts express look exactly like the oem. That's how the Chinease manufacturers draw you into buying them. They are copies of the originals, but in quality, they do not match the originals.
@@LincolnRon It always irritated me why so many expensive speakers had foam surrounds that without any doubt would fail. My brother had the home version of Altec Lansing's 'Voice of the Theater" speakers.15" woofers with foam surrounds that rotted away by 15 years. I have 4 ADC 303ax from the early 70's. Cloth surrounds impregnated with a tacky treatment. They are all now as as good as when new. Same with a pair of Dynaco A25's with rubber surrounds, good as when new. All of my newer woofers & subs have rubber surrounds. Tough as a car tire sidewall.
@@mjnc3672 The rubber surrounds from the 1970s weren't as flexible as modern rubber surrounds. And I'm guessing fabric surrounds were more expensive to make or to install than foam surrounds.
You are welcome to your opinion, but many of us really like the sound of these speakers. Too often people connect these speakers without the equalizer, and then they sound like crap.
Jim Litz ok , capisco l interesse “storico” ma non sono più diffusori attuali nati in un periodo in cui valeva tutto e il contrario di tutto .. il concetto della sorgente ideale è lontanissimo.. basti pensare che il sistema aggiunge l 80% di suono riflesso ad una registrazione che CONTIENE GIÀ LA GIUSTA QUANTITÀ DI RIVERBERO... io ho ascoltato questi diffusori con il loro eq. in un ambiente dedicato .. ma basta ascoltare un assolo di chitarra per rendersi conto che non è rappresentata correttamente.. appare ENORME e se si ascolta un coro non è possibile localizzare gli esecutori.. sintomo di una grave mancanza sulla ricostruzione della scena sonora .. il “fuoco” poi è uno dei loro peggiore difetto ... sull eq. poi vorrei dire che anche modificando il segnale in ingresso all amplificatore non si trasforma fisicamente il componente .. faccio un esempio .. se aumento a livello di eq. le frequenze sopra i 10 khz non trasformo il larga banda in un TW .. basta pensare alla dispersione che ha questo cono da 10 cm a quella frequenza.. e come tutti sapranno la forma a cupola di un TW è molto diversa da quella di un Woofer .. diciamo che è un esperimento il progetto 901 e se uno cerca un diffusore da ascoltare distrattamente senza pretese va benissimo... poi in fondo chi sa apprezzare di meglio e una ristretta fascia di persone chiamate “ audiofili” che mai accetterebbero i compromessi dei sistemi BOSE . Me compresa . Buoni ascolti .
Enorme sensazione causata dal fatto che la riflessione crea l’illusione di un diffusore molto grande. Se l’occhio però vede un diffusore enorme il palco che l’orecchio percepisce è giustificato e il cervello lo accetta. Basta ascoltare al buio e l’orecchio non viene più “traviato” dalle dimensioni dei diffusori. E per quanto riguarda focalizzazione è corretta, basta ulteriormente migliorarla attraverso elettroniche pregevoli. Chissà perché sempre e solo gente che ce l’ha con Bose, chi le possiede mica si accanisce con chi preferisce emulare un ascolto più simile alle cuffie che altro. Un evento reale non è percepibile dallo stero come naturale. Tutto ciò che non è live, si emula, a partire da quando si registra. Anche una 901 emula, ma tenta la strada di ricreare ol suono percepito sul luogo originale fra le mura domestiche. Che può piacere o meno, ma non è detto che sia sbagliato. 😊
Nice work, bad hardware. Chinese clones. Genuine Bose drivers are another story. Reafoam originals instead, wich are 0,9 ohms! All aluminium, not copper, including aluminium helical voice coil.
Stop doing the thing with your tongue, making the smacking noises. Every time you began to talk or paused for thought “SMACK”. It made it hard to watch this otherwise informative video.
What a NEAT set of speakers! I love vintage Bose stuff! I grew up looking at the woofer in my Dad's 301's, and getting yelled at for pushing the dust cap in on the woofer :) I remember watching when he replaced the woofers from foam rot (this was probably 25 years ago). I THINK he tried a refoam, but I can't remember, but I do remember him installing new woofers. I want to find a pair for myself now and fix them up.
To each his own but in my opinion definitely should’ve took the time and repaired the original driver surrounds. Original Bose is the way to keep it and will sound better and hold its value.
👌👌
The replacement speakers are probably better quality than the originals.
Replacing the surroundings on a speaker is pretty time-consuming. No way I would want to replace eighteen of them, especially on a one-trick pony like the Bose 901. I had a pair in the 1970s and they sounded really good (If you took the time to place them in the room properly.) for Classical music and Folk music but lacked the highs and lows for Disco, Rock, Pop, Funk, and Country music.
very helpful. Thanks!
Excellent ! Bonne vidéo 👌
Merci beaucoup 👌
Michel 04 France
I'd love to see what's inside, how they are wired, and the eq
Nice job!
Can you tell me how meany watts out put each speaker
Thank your for this video.
David Rousseau, you worked at Bose from 184 to 2009? Wow, that's 1825 years. You deserve a gold watch!
The second cabinet on the bottom with no screws holding in the drivers might be a clone of a Bose 901. I worked for Bose from 184 to 2009. I do not remember ever seeing a 901 that did not have the traducers screwed into the cabinet. Very interseting for me. Thanks for posting.
Some of these Bose series used a twist-in mount for the speaker drivers.
Interesting, never seen one before
they are genuine bose , ive seen these , there older then series 5
David Rousseau, you worked at Bose from 184 to 2009? Wow, that's 1825 years. You deserve a gold watch! ;-)
GREAT VIDEO THANKS
What you going to do with the old ones man
I noticed the speaker drivers have a weird shape not round like a typical driver
Back in 1989, Bose replaced my 901 with a new pair because of this issue. The 901s had lifetime warranty back in 1980 when I bought them, not sure if this is still true,
No. I called them. Not under warranty. And they no longer sell those particular drivers.
How did you twist out the ones on other cabinet?
As I recall the speakers can be mounted two different ways depending on the cabinet design -- either screwed into place, or twist-locked into place. The twist-lock should simply be "untwisted". But that might be difficult if the gasket has hardened. Using screwdriver and hammer to gently untwist the speaker might help.
Ok for what its worth. I have had 3 pairs of these. IIIs and IVs. The Bose used a Computer to tune all of the HVC Drivers to play exactly the same. Also the Bose speaker had Flat Wound Aluminum Voice Coils to produce the High Frequencies. Im curious to what kind of coils these have and if they were tuned or not. I never heard these played and you have to have the EQ to work to help with the frequencies to make these Cabinets come alive. You have possibly 6 years of life with this. Why not get the weather proof kits that go with the original instead of going this far to replace?
The "weather proof" kits that use a fabric surround will change the compliance of the original speaker drivers, and the free air resonance will also change. The fabric surrounds are not as stable under high excursion of the cones, so they 'pleat' and can produce self-noise or cracking over time. Newer speakers are now made with polyether foam surrounds (instead of polyester foam) and they tend to last longer than the original polyester foam surrounds which were more susceptible to dry rot. I suspect that with non-matching pairs of speakers like the owner has, these replacement drivers will go a long way to helping the speakers 'match' in sound. If it's possible to re-foam the original drivers, I still recommend that, but if there are damaged or missing drivers, or if they're in really bad condition, these 901 replacement drivers are probably just about as good.
How does wrapping the wires verses soldering compare . Bose always wrap the wires.
Wrapped wires were a time-saving step on an assembly line. (This was before robotics became so common in factories.) There was a Dremel-looking device that hung from the ceiling that had a spool of wire threaded in it. It was a lot faster than soldering. Most likely it is a slightly inferior connection to a soldered connection.
It's a better connection to wire wrap. No cracks in the solder due to vibration and more surface area.
What's your opinion of the parts express replacements? Thinking of doing my series V with them. Just sent the EQ to
Rain city
I was very pleased with the replacement drivers from Parts Express. While it's certainly cheaper to replace the foam surrounds, it's much faster to simply replace the drivers. How old are your 901-V's? Surprised that the speaker surrounds have already deteriorated.
Not sure how old they are. I put new foam on them but at least 3 are rubbing voice coil or VC could be
bad. I didn't use shims per video I watched. I have heard good reviews about the PE drivers but I also
see some good original Bose drivers now for sale at about same price. Thanks for the video
Yeah, the rubbing voicecoil problem was one reason I didn't want to try just replacing the surrounds. Based on my research, the Parts Express drivers have the same specs as the original Bose drivers. They sound great again!
Parts Express drivers are possibly made in China and have copper voice coils, 901's have had since the 70's, helical voice coils, rectangular aluminum wire wound on its thin edge to tolerances of 0.001 inch by computer controlled machine. Also injection molded plastic basket/frame that does not distort magnetic field, etc. www.bose901.me
@@Paufit Not possibly, they are made in China.
may i know what is the impedance ? If i want to connect a home theater amplifier of 8ohms out put i need to change the wiring ?
Bose 901 speakers have an 8-ohm impedance. Each internal driver has a 1-ohm impedance, but they are connected internally to provide an overall 8-ohm impedance to your amplifier.
thank you
You can still connect 4 ohm impedance up to a rated 8 ohm output source. Power factors will change. Impedance is kinda of like resistance but it doesn't follow the Ohm Law V=IR. Impedance for this circuit would follow the Induction formula of Z Sq = the Sq Root of R Squared + X of L squared. Z is Impedance. Z is reactance . A little more complicated. This because Inductance will lead Capacitive current by 90 degrees Thus the the impedance of an inductor or speaker in this case. Now XL, is the product of 2 times p (pi), or 6.28, the frequency of the ac current, in hertz, and the inductance of the coil, in henries. As you can see, Freq plays a large roll so Impedance really can change from micro second to micro second depending on the source. Playing Led Zeppelin or Taylor Swift? Lead Belly would be a lower number ; )
@@litzdog911 "Each internal driver has a 1-ohm impedance, but they are connected internally to provide an overall 8-ohm impedance to your amplifier."
Wouldn't that be 9 Ohms since there are 9 speakers?
@@LincolnRon Yes. 9-ohms is still pretty close to 8-ohms. At least close enough.
You didn't make it clear whether the replacement drivers are actually BOSE or not.
The drivers came from Parts Express. I don't think they're original Bose drivers.
Unfortunately these are not they same drivers as the original. They will sound no where near as good as the genuine replacements. A lot of engineering went into the original drivers.
Well, they sound awesome to me. And way easier than repairing 18 speakers!
I rebuilt my Bose EQ with high end audio grade capacitors $11.00 in parts. If you have technical ability don’t pay outrageous fees for snake oil.
Where did you get the Caps from?
WOW, even the back plate label on the 901 is not Bose, you may have two clones.
Huh? Of course they're genuine Bose 901 Series III speakers.
They are from before my time. I worked with series 5 and 6. Nice video.
Why your new speakers are Made in china ? Does'nt matter ?
Not criticizing your decision to replace the drivers, but replacing the surrounds is not a difficult project. It's a little tedious, but very inexpensive.
It's a LITTLE tedious?
Replacing EIGHTEEN surrounds would be extremely tedious.
The benefit of replacing the surrounds is you are assured the drivers are factory original Bose, made in Framingham, Mass. Of course the replacemant drivers from parts express look exactly like the oem. That's how the Chinease manufacturers draw you into buying them. They are copies of the originals, but in quality, they do not match the originals.
@@mjnc3672 The original Bose 4.5" speakers weren't very high quality to start with, especially by today's standards.
@@LincolnRon It always irritated me why so many expensive speakers had foam surrounds that without any doubt would fail. My brother had the home version of Altec Lansing's 'Voice of the Theater" speakers.15" woofers with foam surrounds that rotted away by 15 years. I have 4 ADC 303ax from the early 70's. Cloth surrounds impregnated with a tacky treatment. They are all now as as good as when new. Same with a pair of Dynaco A25's with rubber surrounds, good as when new. All of my newer woofers & subs have rubber surrounds. Tough as a car tire sidewall.
@@mjnc3672 The rubber surrounds from the 1970s weren't as flexible as modern rubber surrounds. And I'm guessing fabric surrounds were more expensive to make or to install than foam surrounds.
im out, to many words not enough wrench turnin................................
Made in China
That's not a genuine replacement Bose speaker it's a China product
Yea it's probably better then bose too! Lmao
Non spendere soldi per quei diffusori.. buttali via e compra qualcosa di meglio .. cioè qualsiasi diffusore hi fi ...
You are welcome to your opinion, but many of us really like the sound of these speakers. Too often people connect these speakers without the equalizer, and then they sound like crap.
Jim Litz ok , capisco l interesse “storico” ma non sono più diffusori attuali nati in un periodo in cui valeva tutto e il contrario di tutto .. il concetto della sorgente ideale è lontanissimo.. basti pensare che il sistema aggiunge l 80% di suono riflesso ad una registrazione che CONTIENE GIÀ LA GIUSTA QUANTITÀ DI RIVERBERO... io ho ascoltato questi diffusori con il loro eq. in un ambiente dedicato .. ma basta ascoltare un assolo di chitarra per rendersi conto che non è rappresentata correttamente.. appare ENORME e se si ascolta un coro non è possibile localizzare gli esecutori.. sintomo di una grave mancanza sulla ricostruzione della scena sonora .. il “fuoco” poi è uno dei loro peggiore difetto ... sull eq. poi vorrei dire che anche modificando il segnale in ingresso all amplificatore non si trasforma fisicamente il componente .. faccio un esempio .. se aumento a livello di eq. le frequenze sopra i 10 khz non trasformo il larga banda in un TW .. basta pensare alla dispersione che ha questo cono da 10 cm a quella frequenza.. e come tutti sapranno la forma a cupola di un TW è molto diversa da quella di un Woofer .. diciamo che è un esperimento il progetto 901 e se uno cerca un diffusore da ascoltare distrattamente senza pretese va benissimo... poi in fondo chi sa apprezzare di meglio e una ristretta fascia di persone chiamate “ audiofili” che mai accetterebbero i compromessi dei sistemi BOSE . Me compresa . Buoni ascolti .
@@manuelaavanzini You are indeed entitled to your opinion. I shall continue to enjoy the sound of my Bose 901s :)
Enorme sensazione causata dal fatto che la riflessione crea l’illusione di un diffusore molto grande. Se l’occhio però vede un diffusore enorme il palco che l’orecchio percepisce è giustificato e il cervello lo accetta. Basta ascoltare al buio e l’orecchio non viene più “traviato” dalle dimensioni dei diffusori. E per quanto riguarda focalizzazione è corretta, basta ulteriormente migliorarla attraverso elettroniche pregevoli. Chissà perché sempre e solo gente che ce l’ha con Bose, chi le possiede mica si accanisce con chi preferisce emulare un ascolto più simile alle cuffie che altro. Un evento reale non è percepibile dallo stero come naturale. Tutto ciò che non è live, si emula, a partire da quando si registra. Anche una 901 emula, ma tenta la strada di ricreare ol suono percepito sul luogo originale fra le mura domestiche. Che può piacere o meno, ma non è detto che sia sbagliato. 😊
❤🥹boes
Nice work, bad hardware. Chinese clones. Genuine Bose drivers are another story. Reafoam originals instead, wich are 0,9 ohms! All aluminium, not copper, including aluminium helical voice coil.
Waste of time
Thanks for your opinion. I did not find it to be a waste of time and remain very happy with the sound quality.
Stop doing the thing with your tongue, making the smacking noises. Every time you began to talk or paused for thought “SMACK”. It made it hard to watch this otherwise informative video.
Well, thanks for pointing that out. I'll try to do better next time.
It didn't make it hard to watch, but it sure made it annoying as hell to listen to.
maybe could have did trade in before 901s were discontinued..for $560.00 two new 901 series VI Ver. 2