I cooked this up in Hornresp the other night. I asked myself how would the original Bose 901 driver (the CTS xxxx 8 ohm, used in series I-II) model if used in a TP? Lacking specs for this driver, I found what I think is a similar current product:
GRS 4FR-8 Full-Range 4-1/2" Speaker Pioneer Type A11EC80-02F 8 Ohm
I found on AliBaba (Express) a Bose-like driver at about double the Parts Express speaker (~14 ea.)
Wholesale Product Snapshot Product name is 4 inch 50 w 8 ohm Audio subwoofer speakers For Midrange Bass computer speaker Freeshipping
but the given specs and the mounting dimensions are much closer to the original CTS drivers (which cost the same or more at least on Ebay). Lacking any ridiculously cheap old 901's for spares lately, I am taking a chance on these Chinese knock-offs. At that price I could re-driver (is that a verb?) a pair of 901s for (duh... 18 x 14.45 = $260.10). Um, I think i will continue buying old 901s for parts... Especially so, as this seller will ship free up to several units, but beyond a certain amount he swaps to EMS and charges fees. This is the first case I've seen where you get screwed on a quantity discount. Odd!
I modeled this several different ways. Rather than a true TH, I got the best curve making a QWT as follows:
I don't know if I'll build one. 13 litres? Still, getting relatively flat 56-357 Hz from a driver with Fs of 100 Hz is pretty darned impressive. Now somebody blow me out of the water by noting that he can get better response using an empty cigarette pack as an enclosure
Oh yes, and it exceeds its Xmax on one watt of input
GRS 4FR-8 Full-Range 4-1/2" Speaker Pioneer Type A11EC80-02F 8 Ohm
I found on AliBaba (Express) a Bose-like driver at about double the Parts Express speaker (~14 ea.)
Wholesale Product Snapshot Product name is 4 inch 50 w 8 ohm Audio subwoofer speakers For Midrange Bass computer speaker Freeshipping
but the given specs and the mounting dimensions are much closer to the original CTS drivers (which cost the same or more at least on Ebay). Lacking any ridiculously cheap old 901's for spares lately, I am taking a chance on these Chinese knock-offs. At that price I could re-driver (is that a verb?) a pair of 901s for (duh... 18 x 14.45 = $260.10). Um, I think i will continue buying old 901s for parts... Especially so, as this seller will ship free up to several units, but beyond a certain amount he swaps to EMS and charges fees. This is the first case I've seen where you get screwed on a quantity discount. Odd!
I modeled this several different ways. Rather than a true TH, I got the best curve making a QWT as follows:
I don't know if I'll build one. 13 litres? Still, getting relatively flat 56-357 Hz from a driver with Fs of 100 Hz is pretty darned impressive. Now somebody blow me out of the water by noting that he can get better response using an empty cigarette pack as an enclosure
Oh yes, and it exceeds its Xmax on one watt of input
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FYI, some measured specs: http://www.diyaudio.com/forums/multi-way/195107-enclosures-old-bose-drivers-2.html#post2771350
GM
Lacking anyone better to do on a Saturday night 
I plugged in the "real" Bose (CTS driver I assume) specs and can sim a toy T-TQWP that is usable maybe 30 Hz to low 200's. I will have to build one once I have a loose driver. 17 liters or so, should make a good project for all my cardbord and coroplast that is accumulating.
I plugged in the "real" Bose (CTS driver I assume) specs and can sim a toy T-TQWP that is usable maybe 30 Hz to low 200's. I will have to build one once I have a loose driver. 17 liters or so, should make a good project for all my cardbord and coroplast that is accumulating.
For original Bose (901 series I, II), they clearly used CTS ("Chicago telephone systems", not a Co. anymore that I'm aware of) drivers, this is even mentioned in the Patent. However, they did in house QC and sorted drivers into three different resonances (part of the design goal). With the explosive growth of Bose Co., it is quite possible they switched to in-house manufacturing later.
It's worth mentioning that the Chinese drivers mentioned in #1 have arrived, but not yet tested. They say "50 watt" but don't seem as heavy as the original CTS drivers. Meanwhile, imagine my disappointment (?) when I could not find what I thought was a defective driver in my currently-used 901 speakers. Meanwhile, as stated elsewhere, I think the cheapest source of 901 parts is old 901 speakers. I just took delivery on a pair ($125). I drove 140 mi e/w but calculate I saved $15 on shipping (ok, not counting food enroute!). Haven't hooked them up yet, but all drivers look good, grilles ok, cabinets with usual scratches of 40 years existence. Just my luck, I wanted a junker for spare parts and I get a perfect unit (maybe). I guess I'll have to build that toy subwoofer with the Chinese driver.
It's worth mentioning that the Chinese drivers mentioned in #1 have arrived, but not yet tested. They say "50 watt" but don't seem as heavy as the original CTS drivers. Meanwhile, imagine my disappointment (?) when I could not find what I thought was a defective driver in my currently-used 901 speakers. Meanwhile, as stated elsewhere, I think the cheapest source of 901 parts is old 901 speakers. I just took delivery on a pair ($125). I drove 140 mi e/w but calculate I saved $15 on shipping (ok, not counting food enroute!). Haven't hooked them up yet, but all drivers look good, grilles ok, cabinets with usual scratches of 40 years existence. Just my luck, I wanted a junker for spare parts and I get a perfect unit (maybe). I guess I'll have to build that toy subwoofer with the Chinese driver.
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