Real Bose 901 Series Is, or what? Need ID help

[severeear]

Hey folks, just got these slightly weird maybe 901 Series Is from a thrift. Can't tell if they are actual 901s with some cab reworking or something else. Appears that the drivers are the real thing, have numbers 5804092S on the driver rear magnets, which are square, treated cloth surrounds. According to this post on the web, these numbers denote originals, http://shopping.feedfury.com/content/43373252-1968-bose-901-series-i-square-magnet-part-5804092.html. Also, a couple of other web references list this number as an original. My best guess so far is that they might be originals that someone put new top pieces on, as the terminals don't look right and are off center, and the top pieces seem like a different wood than the bottoms. Her's a link to the closest set I could find: http://seventiesstereo.blogspot.com/2011/02/bose-901-naked-photos.html
Anybody care to weigh in on what these may be. BTW, the drivers are in excellent shape, and seem to all work.

 

[Dan ʕ•ᴥ•ʔ]

Look like home brew Series I to me.

 

[Kingshead]

Look like home brew Series I to me.

That or a prototype someone took home. If so might be worth some investigating. My reason for this, if making a copy why would they off center the front driver. That said, they do look like home made, but prototypes often do as well, just food for thought.

Martin

 

[barkerd]

homebrew. Usually a proto might be rough but it would be made accurately (see connection terminals)

 

[Kingshead]

homebrew. Usually a proto might be rough but it would be made accurately (see connection terminals)

Agreed, but if a prototype they would be very old and might have seen some repairs/modifications over time by the person that obtained them back when.

 

[Copa1934]

Hey folks, just got these slightly weird maybe 901 Series Is from a thrift. Can't tell if they are actual 901s with some cab reworking or something else. Appears that the drivers are the real thing, have numbers 5804092S on the driver rear magnets, which are square, treated cloth surrounds. According to this post on the web, these numbers denote originals, http://shopping.feedfury.com/content/43373252-1968-bose-901-series-i-square-magnet-part-5804092.html. Also, a couple of other web references list this number as an original. My best guess so far is that they might be originals that someone put new top pieces on, as the terminals don't look right and are off center, and the top pieces seem like a different wood than the bottoms. Her's a link to the closest set I could find: http://seventiesstereo.blogspot.com/2011/02/bose-901-naked-photos.html
Anybody care to weigh in on what these may be. BTW, the drivers are in excellent shape, and seem to all work.

Drivers are the only thing that look "correct" if you will. That said, they look pretty accurate. As for the off center driver that is normal for Original and Series II. Series three and later had the molded baffles and center mounted front firing driver. You'll also note the III and later had the ports sticking out the front on the left and right of the center speaker. Assuming they are Bose drivers or correct CTS drivers, you'll merely need an original or Series II EQ to make them really sing.

I posted a similar speaker, maybe a couple years ago. Had all CTS drivers. Sounded good, but definitely needed the EQ. Polk made a set and got some heat from Bose over it.

 

[severeear]

That or a prototype someone took home. If so might be worth some investigating. My reason for this, if making a copy why would they off center the front driver. That said, they do look like home made, but prototypes often do as well, just food for thought.

Martin

Hey Martin, thanks for the reply. When you say 'might be worth investigating' what do you think my next step should be in investigating?

 

[Putterman]

Stereophile reviewer Robert Reina mentioned in a review of the Smaller Advent that 'A student had somehow got hold of the parts list and assembly instructions for constructing the 901. For $120, he would sell you the instructions and all of the parts needed, sans lumber and grillecloth, to assemble your own set, a legit pair of which cost $800. About eight in our group built their own Bose-o's, as we called."
This may be one of them.

http://www.stereophile.com/historical/506advent/index.html

 

[AudioMayhem]

Are the driver connections wire wrapped?

If so I'd say they are legit Bose.

 

[Soldermizer]

You definitely have a "strange egg" there ! I am a happy (deluded?) owner of currently 4 pair of 901 series I or II. From reading the Stereophile link above, I note with amusement that you can buy a used pair of the 901s at a fraction of the original price ... certainly adjusting for inflation. I accumulate mine on Ebay and pay anywhere from $150-300 the pair.

 

[dshoaf]

Pull the drivers and inspect them for a 3 by 3 part number in this format: xxx-xxx.

Those are CTS drivers most likely but Bose would have had one of their part numbers stamped on the magnet structure. AudioMayhem is also on the right track. Bose did not go to the wire-wrapping technique until the Series III's came out since that was when the switched to a driver of their own design for the 901. They maintained the relationship with CTS for some time after for other models in the product line.

If you check the wiring of the 9 drivers, they should be in a series/parallel configuration as the Series I/II were 8 ohm CTS drivers. Bose switched to 0.9 ohm drivers starting with the Series III's which were wired in series (9 drivers x 0.9 ohms = 8.1 ohms).

The cabinets are well-done but still retain elements of homebrew. The corners of the cabinet are well executed, for instance.

The access hole to the 2 terminals is too small and square - not rectangled. There's no evidence of a model label or serial number sticker. The grille cloth is not the kind ever used by Bose. I couldn't see the grill cloth frame but am willing to bet it isn't the same type of pressboard, too.

Lastly, during production, manufacturing placed a small paper tag inside the stuffing of the last speaker with the serial number and some production data numbers. If it isn't there, it ain't a Bose product.

Cheers,

David

 

[severeear]

Pull the drivers and inspect them for a 3 by 3 part number in this format: xxx-xxx.

Those are CTS drivers most likely but Bose would have had one of their part numbers stamped on the magnet structure. AudioMayhem is also on the right track. Bose did not go to the wire-wrapping technique until the Series III's came out since that was when the switched to a driver of their own design for the 901. They maintained the relationship with CTS for some time after for other models in the product line.

If you check the wiring of the 9 drivers, they should be in a series/parallel configuration as the Series I/II were 8 ohm CTS drivers. Bose switched to 0.9 ohm drivers starting with the Series III's which were wired in series (9 drivers x 0.9 ohms = 8.1 ohms).

The cabinets are well-done but still retain elements of homebrew. The corners of the cabinet are well executed, for instance.

The access hole to the 2 terminals is too small and square - not rectangled. There's no evidence of a model label or serial number sticker. The grille cloth is not the kind ever used by Bose. I couldn't see the grill cloth frame but am willing to bet it isn't the same type of pressboard, too.

Lastly, during production, manufacturing placed a small paper tag inside the stuffing of the last speaker with the serial number and some production data numbers. If it isn't there, it ain't a Bose product.

Cheers,

David

Thanks for the response, good info--here's a link to the same drivers I have with the same numbers on the back of the magnet http://shopping.feedfury.com/content/43373252-1968-bose-901-series-i-square-magnet-part-5804092.html