Bose 901 Modifications

[901Fixer]

This board will really open your eyes to how inexpensive superior hi fidelity can be. Also how cheaply built many expensive famous named products truly are. I love to build things anyway so additional reasons make it impossible to resist.

[Ron E]

Originally posted by Nelson Pass
I do have some cut for 21 8" full ranges. Let's see, 42 PM5A's or a
new Porsche...

So from 2 in big horns to 42 on sheets of plywood?

[boseman]

Everything said in this thread has some truth, however I had bought the guide you had mentioned and performed the modification.

The mod worked like a charm and if you read the guide it lead you through the entire steps on how to procure the drivers cheaply and recoup your money at the end of the project.

The guide is no longer available on Ebay it seems, but I found it at 5.1.cashkats and of course . com.

boseman

[901Fixer]

Originally Posted by boseman

Everything said in this thread has some truth, however I had bought the guide you had mentioned and performed the modification.

The mod worked like a charm and if you read the guide it lead you through the entire steps on how to procure the drivers cheaply and recoup your money at the end of the project.

The guide is no longer available on Ebay it seems, but I found it at 5.1.cashkats and of course . com.

boseman

Did you replace the front mounted driver with a different full range driver or stick with all 9 Bose?

[boseman]

I stuck with all 9 Bose drivers, you should go to 5.1.cashkats .com and read what it will do.

I don't want to reveal everything because I have become friends with the owner of the guide and don't want to take any business away from him.

Thanks,

Boseman

[BHTX]

I'm guessing everyone has seen this:
Replacement Speaker Driver for Bose 901 4-1/2" 1 Ohm

Along with the measurements:
R901 LMS Impedance vs Frequency Graph
R901 T/S Parameters and Impedance Graph

Doesn't seem half bad to me. If it weren't for the 1 ohm impedance, I wouldn't mind having a pair to mess around with.
As for mounting 8 of them on the back of a box to splash all over the front and side walls..

[boseman]

I'm with you on that, I would rather have 9 - 8 ohm drivers wired in series/parallel than 9 - 1 ohm drivers wired in series like Christmas tree lights.

Boseman

[Fast Eddie D]

You can replace the foam surround with this kit.

Surround Kit For Bose 901/802 Speakers 260-910

I used a kit like this for my old 301's that do shop duty. It worked great. The kit comes with everything you need, except some isopropyl alcohol. Some extra Q-tips are handy too.

[boseman]

Replacing the surrounds is definitely the way to go, however I don't think I would waste much time on those Series III-VI drivers...

Boseman

[Soldermizer]

Perhaps I'm responding a bit late, but so what??? I speak from some experience, having owned a total of six pairs of 901s in the past several years. All of them used, ancient. Three pairs of series IV or V. Without exception, the surrounds were "dust" and I replaced them. Of three pair, I was able to get "almost" two pair near-perfect. This probably reflects a combination of my hit or miss re-coning skills and also the failure rate of the repaired drivers. I listened by ear and kept the best ones. In any case, I've sold off the 901 IV or V projects and/or given them to grateful friends.

What I would like to share is the following: I've also bought (1) 901-I and (2) 901-II. THEY WERE IN PERFECT PLAYING CONDITION (at least as far as many hours of listening could determine.) The 901-III and later were literally a different type of speaker (ported instead of acoustic suspension.) Some writers claim, and my experience agrees, that the original Bose 901 (I & II) were a better overall speaker.

Therefore, my advice is lose the newer stuff and get thee a pair of 901 I or II. No EQ? No problem. They are over-priced for what they do. Get a Behringer DEQ2496 or similar auto-EQ unit and you can equalize (or equalise in the UK) both speaker and room in one go. At least at US ebay prices, a pair of series I or II should cost you not more than $300. The EQs go for $50-100. Use it if included. If you really want to know, I will share my link(s) for 901 articles. Email me.