Bose 901 How to identify series model

[tonyleeusa]

Can anyone show me how to identify Bose 901. The label in the front under the grill says: Model #901, M.O. #3098, Serial #490518.

Also, do these have to be used with the equalizer designed specifically for them? What if the equalizer is gone? Would an ordinary 10 or 12 band graphic eq. works?

Thanks for your help.

[Guest SpeakerRookie]

The 901 series will usually be printed on the nameplate. If it has no series listed it may be the original series I. I would suggest go to eBay and look at the auctions for 901s and you can do a visual as to weather they have ports on the back a side moulding etc and identify your that way.

As for the eq you can only use certain ones with each other. I believe 1&II or III&IV or IV&VI. But it would be best to get the right series just for common sense sake, plus I would think it would help the resale value. I have a series VI eq I would trade straight up for a series I. Copy and past this link in your browser at the bottom it give more info on the compatability of EQs. Good luck.

http://www.shopping.com/xPR-Bose_901_VI~RD-105506836100

[soundminded]

Bose 901 original (series I) and series II are nearly identical. The speaker enclosures are all wood, are sealed acoustic suspension types, have all straight surfaces, and came with a beige grillcloth. Series II had a small silver "BOSE" logo fixed to the front lower right corner of each cabinet but if you replaced the cloth grillcloth with the walnut trim, they would look identical. The drivers and cabintes of I and II are also identical, the only difference I am aware of is that the segregation of drivers supplied by CTS into three groups of matching units was done by computer. The series II equalizer is also slightly different having more high frequency boost curves and fewer cut curves (series one only had 2 boost curves and 7 cut curves, plus one indicated as flat. In general the series I and II have held up remarkably well with no signs of deterioration in my series I after 35 years of ownership. Starting with series III, the design changed radically. The system became a ported design, Bose manufactured the drivers themselves using foam surrounds which did have a much greater tendency to rot and crumble, and the working enclosure is made from an injection molded plastic. You can identify it by two small pipes projecting through the rear grill cloth. The ported design is more efficient than the original but with a loss of almost a full octave of bass. I do not know how to distinguish between III, IV, V, and VI. In general, except for the interchangability of the equalizers for series I and II, I believe each series requires the correct equalizer.

The equalizer is a critically designed precision circuit whose characteristics compliment the 901 enclosure exactly. It is as critical to use the equalizer and the right equalizer for 901 as it is critical to use the right crossover for a conventional loudspeaker. This does not mean that you cannot use further equalization if you want to but if you do, be aware that you have already started with considerable boost at some frequencies and you can overdrive amplifiers as I can personally attest.

BTW, my experiments with 901 series one have yielded very pleasing results. I may buy more to convert the way I've converted my own.

[Guest jbangelfish]

If it just says 901, it is the original, series I. The other series were always followed by roman numerals, II, III, IV, V and VI. The series I EQ can be identified by a lighted, clear plastic, on/off switch. You should use the appropriate series EQ and they are often sold by themselves on ebay. Series I and II are the best of them and still good after all these years. Later series had many problems, including foam rot and a great loss of bass, restricting them to around 40 hz. I's and II's will reach the low 20 hz region. They need lots of power (around 200wpc) to really appreciate them and they absolutely need corners and a solid rear wall. If you don't use them as they were intended, you simply won't like them.

Bill

[george nakamoto]

I have the seies 2 speakers I bought new back in I think 1972. the original and mine look the same the 3 thru 6 has those 2 ports in the back. I've read that the 1 and 2 used real wood. I don't know about the inside wood but the out side wood is particle board wood. I also agree you should use the right eq because it is part of that speaker system. as far as the surrounds are concerned, the 1 and 2 used cloth. I had 3 of my speakers fried with dc current from a phase linear amp which they were knowned for. I had the 3 rebuilt at this repair facility in los angeles. my other one is still original and all 4 still sounds good today. the repair facilty said bose has an exchange program where you send then your current speakers and they will sell you a current model at a discounted price, but they told me that most people were more happy with their older speakers. I also asked them what does bose  do with the speakers you send them? he said bose repaires them and sells them to their employees. I don't know if it's true but that's what he said. also I read many reviews about the 901 series 1 and 2 in the early 70's stating that they were power hungry. I've read many people didn't like the sound. maybe because at that time most people had recievers which most had less then 50 watts a chanell. the reviews I read reccomened at least 100 watts a chanell.