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Bose 501 II journey

Copa1934

Copa1934

My ears are bleeding
A year or so ago a friend gave me these speakers. He had acquired them in a barter for services. I think he got the short end of the deal, and this has nothing to do with Bose. I had seen them when visiting and we talked about the briefly. They were stacked near a doorway collecting lots of dust. He had them for years and hadn't messed with them. One day he contacted me and asked if I'd like to pick them up. If you know me, the answer was obvious. I'm figuring he examined them before contacting me and likely gave them to me because he wasn't up for the challenge. Looking at the images you'll understand why.

At some point a prior owner installed a RS 40-1014 (which I would later reuse) and a 12" white cone of Korean birth. The hack job to install the 12" was astounding. When I look at the work I start thinking Banjo music and places you really want to avoid.

I'm going to make separate posts so I can adequately explain what goes on. As I said I had these for some time and kept looking at them and thinking "yes I can"..."no I can't"..."yes I can"...and then moments of why? Well two weekends ago I finally said "the heck with it". I know I have the skills, the tools and the materials so why not. Mostly I've been holding out for correct replacement woofers, but still haven't acquired them. I would prefer to stick with Series II woofers to keep it correct.

For anyone interested here are some basic dimensions...
Lower cabinet section (housing the woofer) DxWxH 14x14x17
Space where tweeters reside 5" height, same WxD.
5/8" particle board. However, the lip where the woofer is attached is roughly 1/2" ply.
 

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Copa 1934:

I picked up a pair of the BOSE 501 Series II a while back with the original woofers that have foam rot. Taking off the 3 sided grills was a challenge, but they did come off without damage. I put them aside for a winter re-foam project. If anything, they will make great end tables in my "Man Tree Fort" (upstairs).
 
Begin of the fix of the hack job...

So, first I had to evaluate the situation. It was obvious I was not going to be able to simply install a new "lip" for the woofer to be mounted, and there was clearly no way of sealing the area around the woofer, so I had to clear out the opening flush with the walls.

Using a Japanese style saw I notched the remanents of the opening (which are visible in the image with the saw) and used a hammer to knock those pieces out. I thought about simply running the saw flush, but there was hot glue all along the underside making it too challenging to keep the blade flush. In case anyone was wondering.

Using a special chisel I would notch the wood at the mating surface to permit the pieces to break clean from the face of the contact area. I would later use a file resting flush with the inside to work the glue off so that I would have a clean surface to work with and for glue to adhere, should that become necessary.

What I forgot to take images of were 3/4" strips I attached on the inside wall to support the new baffle during installation. This ensured that the baffle would sit flush with the front edge of the walls.
 

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Baffle time...

Some time back I purchased a pair of Pioneer CS-77 speakers. One was gorgeous, the other had fallen from a shelf 12' high onto a concrete floor (in the garage). The one that had fallen looked like a boy scout group had practiced first aid using Duct Tape. When I got that off it was very clear I was not going to be able to put Humpty Dumpty back together again. So I parted them out. Still have the one good cabinet and the back panel from H.D. would be used for the baffle on the Bose. An upgrade perhaps? Maybe, we'll see.

One image shows the back panel next to the 501 cabinet, which hasn't had all the opening cleaned out, yet. The next image jumps right to the test fitting of the front (formerly rear) baffle. The next is my cutting out the hole for the opening.
 

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More baffle work...

To get the correct size, accurately, I clamped the new baffle against the "good" cabinet, after rough cutting the opening. Then with a router and bit with bearing "traced" the opening. Since I couldn't "attach" to the baffle without leaving permanent marks I chose to route one side, then move the clamps to the opposite end for the remainder of the opening. Perfect match!

Note the one image showing a close up of the router and bit. There is a precision bearing at the end allowing me to use a surface or template as a guide.

Next was the "lip". Like the original I used a sheet of 1/2" plywood cut to size, then drilled and then cut out for the rough opening. Once again I clamped that up and performed the same routing to get the correct opening size. One of the images shows the two pieces glued up. The heavy "bead" is to ensure a good tight seal.
 

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Ah the grill...

The grill that was on the cabinet with the over-sized woofer was so butchered it was breaking up.

So, taking a thick piece of paper, not quite cardboard and heavier than poster board, I place it between the cloth and the Masonite of the "good" grill to create a template. I only needed the front facing piece since the sides were undamaged.

The template was then used to transfer to the plywood replacement. I used a square to make sure the cutout was reasonably true and accurate. I did a check and found the fit fine. Because the ply was slightly thicker than the Masonite the overall dimensions are just slightly smaller. From the final piece I'm going to make a proper template. Then I'll use 3M spray adhesive to mount the grill cloth to the new form.
 

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Home stretch..

Since I'm not yet finished with the grills I'm not going to say "complete". However, I will say that I am pleasantly surprised performance wise. When you look at the images please note these are NOT placed ideally. I just wanted to get a listen to them and I was not disappointed. Granted my only cost was a matching woofer, another RS 40-1014, so my total investment was minimal. But I've read many posts of people getting freebie speakers and ranting over how terrible they were.

Sorry the images aren't so great. The cabinet to the left is the one that was totally butchered. Some of you, no doubt, recognize most of my speakers. Only "weak" point I can say is in the mids. I know this because when I turn on the Mach One's or the AR3a speakers I mostly here an increase in mids. Mid bass, and bass are more than acceptable. When talking about deep bass, it's there, but certainly not as present as the Mach One or the AR3a or their big brother 901 (which aren't viewable in the images). Highs are very good. Imaging wasn't bad in spite of the bad placement.

To do a proper audition I'll need to rearrange one of my 3 listening "walls". I need to give these speakers adequate "reflective" surfaces. I'm thinking the mids will improve, and certainly the imaging.

I would never classify these as junk or poor speakers. Given the speakers I own I'd say I'm in a fairly good position to "judge" speakers. I own a couple JBL, I've listened to Beveridge, DIY horns, K-horns, etc. And while the 501 is not in the same "league" as some of the much more expensive speakers out there, it certainly does very well and better then some "touted" speakers. But, I still have to do a proper audition.

When the grills are completed and the speakers properly placed, I'll update this thread.

Hope you enjoyed it.
 

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Dang. What a busy little woodworker you have been today Copa !

I was expecting this to be at least a weekend project, but an afternoon?? Wow.

Very nice work indeed. Most would have laughed and tossed it in the burn-pile. Gives us all motivation that no matter how bad things looks, there is always hope.

Thumbs-Up to you, Sir :thmbsp::thmbsp::thmbsp:
 
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Hey Copa,

I really enjoyed reading your descriptive text, and viewing your pics. Impressive work and lots of fun!
It's nice when you have a chunk of time to really focus on something like this, and have the right tools! No mental disruptions. Will you try to locate original woofers or leave them as is?

Look forward to the next phase and pics.

Glenn
 
Beautiful workmanship. You make me want to get a shop set up to do this kind of restoration. I passed on some AR 3s last year because the cabs were so rough and needed your kind of attention which I did not have. Keep up the posts - truly inspiring.
 
GD70 said:
Hey Copa,

I really enjoyed reading your descriptive text, and viewing your pics. Impressive work and lots of fun!
It's nice when you have a chunk of time to really focus on something like this, and have the right tools! No mental disruptions. Will you try to locate original woofers or leave them as is?

Look forward to the next phase and pics.

Glenn
Click to expand...
I'm still hunting for original woofers. One of two things will happen. My friend will buy them as-is, or I'll locate woofers and then he'll buy them. He likes them as-is. He too was pleasantly surprised at the sound reproduction, even with RS drivers.

To everyone who followed, Thank you for the compliments. It's inspiring when people show their appreciation. Having the right tools, and few interruptions can make quick and sometimes light work of things.

I built my first, cardboard box, speakers in my late teens. Because I learned woodworking, from watching my father and some classes in school, at an early age it didn't take me much to build some wood speakers afterwards.

Between my love of audio and woodworking, I never seem to run out of fun things to do.

RRR - Recycle, Reuse, Refurbish. Thankfully we have good foundations to work from.

The guy who gave me these 501 speakers just gave me a pair of Coral BX-1101 speakers. I hooked them up this weekend, and well they need some help. Missing grills so I'll have to get creative with these buggers. That will someday be another post.
 
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