Speaker Re-Coning 101 by Grant Stoner


Well, I may call it re-coning 901, because this is partly about the process of reconing speakers and the illustrious Bose 901’s.

Yes, I know, the Bose 901’s aren’t exactly  revered in audiophile circles, and for good reason.  But for some of us older folks, they were  a formative listening experience.  1978.  My older sister took a friend and I over to her friend’s house and we listened to Van Halen’s just released first album.  I was of course blown away by the guitar playing and music, but also the incredible loud stereo they had which featured yes, Bose 901’s.  Now my mature audiophile ears may not be so impressed, but we’ll get to that.

So, for nostalgia’s sake, Leslie bought a pair at auction for a reasonable price.  They looked mint on the outside…not so much inside.  All the surround cones had deteriorated, which does happen to many speakers of the era.  These were series III circa 1976 by the way.  Buy new drivers, of which there are 9 in each speaker, which could be rather expensive, or re-cone them?  Re-coning is far cheaper.  “Simply Speakers” sells re-coning kits for many vintage speakers, we got the one for the 901’s which only cost $30.  It comes with 20 fabric cones (a few extra) and 2 tubes of glue.

The process is fairly simple, but with 18 drivers total, rather time consuming.  You have to immaculately clean the old residue off and carefully glue each surround on.  Fortunately one was already cleaned which saved me at least a half hour.  The whole process took me a bit over 3 hours, we let them dry for a bout 5 hours then fired em up.

The sound?  Well frankly they sounded horrid.  All midrange and not very good midrange at that, no bass or treble.  So we applied SVS subwoofer and 2 Aperion super tweeters and they still didn’t sound very good.  Well the turntable was the cheapest Rega but nice everything else.  What gives?  Then we ran  JRiver thru the computer and some heavy equalization (boost bass and treble and severely lower midrange) and voila.  It actually sounded respectable.  Not great, I would say some $500 ELAC mini monitors would sound better. Now at this point we tried something else which forced me to re-write the entire ending to this saga.

We fortunately did get the Bose equalizer with the speakers.  Being audiophile purists, we didn’t want to disrupt the signal path with such a device.  But thankfully we did.  You can hook it up in line between the preamp and amp with RCA’s.  If you didn’t have separates you can loop it thru a tape monitor circuit.  We unhooked the sub and super tweeters to give a proper comparison, fired them up and guess what?  They sounded far batter.  Solid bass and much higher range in treble.  Boosting each sounded even better.  There’s even a sub-sonic switch that killed a rumble coming from the turntable.  Then we added the sub and super tweeters and that just added to the goodness.

Using the provided equalization (EQ) is definitely a requirement.  Even with the adjustments at flat, it does something magical to the sound.  Ours did add a slight hum, but there is a service that upgrades the eq which I’m sure we’ll try.  For example, DHS Speaker Service (http://www.dhsspeakerservice.com) provides classic speaker repair and restoration along with EQ upgrades for the Bose 901 series among other services.

So the overall sound?  Imaging isn’t really precise but with the reflection the sound is quite expansive and sounds pretty good at numerous locations in the room, everywhere in the room actually.  Not the last word in resolution of course, but not bad.  And they are capable of major SPL’s.  Great for parties in a large house.

So would I recommend them?  Well, yes.  Not for your main audiophile system, but maybe for the main living room.  They are lifestyle type speakers.  With the Saarinen like pedestal stands they look so retro-cool.  They were never intended to be pure audiophile speakers, but they do what they do well.  I would say add a sub and super tweeters.  They do bring them up a major notch towards high fidelity.  And with the 18 drivers, they are great re-coning practice.  Now that you know that process really isn’t that difficult, you can seek out all those old speakers from your past you always wanted to try.   Say you find some DQ-10’s or old Advents at a flea market, or a garage sale, go for it.  Or the old 901’s.  Forget the audiophile bias.  Put em in the family room, it’ll keep the kids from using your audiophile system.  And it’ll make your non-audiophile friends happy.  Of course some will try to argue they are the greatest speakers ever.  Don’t bother responding.  We know better.  But they are fun so what the heck.  Cheers!



One thought on “Speaker Re-Coning 101 by Grant Stoner

  1. Grant I was impressed with the Bose 901 in 1972 when demonstrated by Robert MOOG with his new, at the time, synthesizer equipment in the engineering lecture hall in my first year studying electrical engineering. They were demonstrated with Crown’s DC300 amplifiers and situated in a quadraphonic configuration. Not to use the Bose EQ with the 901 as the manufacturer designed it to be used because you think yourself a purist is an interesting though not unexpected perspective. Audiophiles that uses EQ to address a number of problems that are easily corrected using it, are apt to believe that you do not regard them as pure and may feel demeaned by your suggestion that they are not “pure” like you and others in the group that are similarly biased. Your remark indicates that you are simply “anti EQ” and believe that because your are, that you may be regarded by others, and of course yourself, as a purist and worthy member of a club. I myself like to remain open to new opportunities, opportunities that allow me to hear the most natural sound that I can manage to get and am not afraid or closed to the use of any appropriate tool in the toolbox.

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San Francisco Audiophile Society

San Francisco Audiophile Society