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Re-foaming the Bose 301 Series

Since getting into the DIY speaker hobby a few months ago I’ve built two speaker systems and am really happy with both of them.  I don’t necessarily need another set of speakers anywhere in the house, but I was given a vintage set of Bose 301 speakers recently.  I’m normally not a huge fan of Bose, mainly because they are way too expensive and I feel that you can get the same, if not better, sound quality from cheaper alternatives.  That being said, I don’t find anything wrong with the sound produced from most Bose products.  Which is why I decided to fix these speakers up to see if I could put them to use somewhere.  This set is going on 40 years old now, but they have survived remarkably well, except for the obvious need of re-foaming.

Manufacturers in the 70′s used some fairly cheap rubber material for their speaker surrounds and most of these have dried up and rotted away through the years.  A lot of people end up just giving these older systems away because of this, “They look horrible, must be broken!”  That’s not necessarily the case.  The foam is probably one of the cheapest elements of your speaker and is pretty simple to replace with a little patience.  I picked up a re-foaming kit from Parts Express for about $20 with everything that you need.

The first step is to remove the old surround material.  As you can see in the pictures (which are in the gallery above in order of construction), mine was pretty much gone already, but you’ll most likely be able to just brush it away with your fingers.  The next step is to remove the gasket around the exterior top of the speaker if yours comes with one.  This is by far the most time consuming and annoying part of the whole process!  Using a razor knife, work your way around underneath the gasket to slowly pry it away from the metal basket.  If it is a paper gasket, like the 301s, then be careful not to rip it because we’re going to use it again.  Take your time and don’t cut yourself!  I’ve heard that a little heat can help with this step, so try passing a hair dryer lightly over the gasket to melt the glue underneath.

When the gasket finally comes off you’ll be left with a mess on the metal cage.  Go ahead and scrape all of this mess away trying to get the metal surface as smooth as possible.  We are going to be gluing the new surround to this, so it should be clean of old debris.

Now we can turn our attention to the cone.  The inside rim of the surround gets glued to the outside rim of the cone, so go ahead and scrape away the old surround material from the outside rim of the cone.  Again, it doesn’t have to be perfect, but should be a pretty smooth surface for the new surround to be glued to.  I used my fingernail mostly, but for the stubborn parts I resorted to the razor knife again.  Be careful not to cut the cone!

The next step is to get the voice coil and cone all set up in the right position.  To do that we need to remove the old dust cap from the center of the cone, which is just there to protect the voice coil from getting debris in it.  My kit came with a new dust cap, so I went ahead and destroyed the old ones, but you can cut around the edge and re-use the old ones (leave a bit of glue left in one spot and just fold the dust cap up out of the way).  Be careful doing this step as well because you don’t want to cut through the cone.

There needs to be a small gap in between the cone/voice coil former and the pole so that the cone can freely move in and out when the music hits.  If the cone is off-center you’ll get the voice coil former rubbing against the pole and hear this awful buzzing sound, along with probably destroying your driver.  To space it out evenly you can insert shims between the two while you are gluing the new surround in place.  The PE kit came with shims, but you can also use paper stacked to the correct thickness.  Go ahead and insert the shims down the sides of the voice coil former around the gap to center the cone.

Now you can go ahead and glue the inside of the new surround to the outside of the cone.  Just go ahead and center the new surround and run some glue around the edge.  It’s a good idea to coat both surfaces with glue first, then let them sit for a few minutes to get tacky, then put the surfaces together and apply a little pressure to create a good seal.  Wait about an hour and then you’re ready to glue the outside of the surround to the metal cage.

But first, in older speakers it’s common for the spider (the normally cloth folded/rippled thing that you can see through the metal cage if you look underneath of the cone) to collapse a little bit.  The surround material is there to help the spider out, so when the surround goes away the spider has a tendency to collapse.  These two things are there to suspend the cone in a neutral position, so it’s free to move both in and out.  Before you glue the outside of the new surround on, push the cone out a little bit until the spider is flat, not sunken in.  The shims that we inserted earlier should be able to hold the cone in that position for gluing.  Go ahead and glue the outside of the surround to the metal cage once the cone is in the correct position.

After an hour or so you can now glue the gasket back on using the same technique.  This will help seal the new surround in place and also protect it from getting damaged.  I flipped the speaker over so it was face down to apply some pressure to the gasket while it was drying overnight, but you can also clamp it with a few hand clamps.  Let it fully dry, at least over night before you move to the next step.

The next step is to remove the shims and glue in the new dust cap.  This is pretty straight forward, but be careful not to get anything in the voice coil when doing this!  Wait about an hour and then you’re pretty much done!  I did a little tidying up of the glue and made the lines a little more even, but that’s really not necessary.  If you’ll see the drivers, then you may want to do that, but mine are going to be covered with a grill, so no real need.

You can now mount them back in their boxes and test them out!  Mine sound really great and you can’t beat the price!  With a $20 kit and a little elbow grease I’ve got speakers that sound as if they cost 10 times as much!

Been a little while now, wow!  The holidays really suck up the time don’t they?  Well, unfortunately the holidays are over, but fortunately that gives me a little bit of time to do some updates.  I’m still working on the latest Blake tutorials, so keep checking.  I haven’t forgotten about him!

For a little teaser until I can get those finished I figured I’d show a holiday image I did in the same 3D anime/manga style.  The modelling was all done in the same way as the tutorial series is going through, including the cloth modifier for the clothing.  The materials are mainly a node based cell shader setup, with some AO and environmental lights for the snow in the background.  There are no lights in this scene!  It renders out extremely quickly if you take out the background, so could even be suitable for a real time character if I paid attention to poly counts.

The one thing slightly different in the material setup is the edge lines.  These were done with the Blender freestyle plugin.  This is the very first time I’ve used freestyle before, so I really had no idea what I was doing, but I think they came out OK.

In order to shorten the production time, the rigging was done with the fairly recent rigify plugin.  This is a really quick and fairly straightforward way to rig a standard bipedal character.  I may or may not go over this in the series.  Using rigify you could really get by without knowing much about rigging at all, but I think rigging skills are useful to learn, so we’ll see.

Happy New Year and enjoy!

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The hurricanes sort of put a halt to the finishing process of my speakers, but I finally got them finished this past weekend.  I’m really happy with the way that they turned out.  They are very stealth looking in the flat black, but the orangy drivers really make them pop, so a good contrast between the two.  The gallery above shows some wip painting pictures and then the finished product.  I haven’t quite arranged the desk for them yet, so the final placement is just temporary at the moment.

I’ll run through my finishing process in a moment, but first my thoughts on how they sound.  In short, awesome!  The first word that comes to mind is clear.  They are super clear, you can hear absolutely everything going on in the music.  Those little tweeters are amazing!  The woofers are crossed over pretty high, somewhere a little above 100, so you need to run them with a sub.  I’m still working on the best placement and sub level, but they sound great already.  I still can’t get over how clear everything sounds.  It feels like I was listening to my old speakers through a diving helmet!

Now for my finishing process.  After everything was constructed I sealed up all the cut MDF edges with plain white Elmer’s school glue.  It took about three coats before they stopped soaking it up.  Next, I coated the entire box in a 50/50 mix of wood glue and water (I used Titebond, but shouldn’t really matter).  I did two coats of this until there was a really good hard “shell” over the whole box.  This step is to get the MDF ready for paint.  Some people will gasp at using a water mixture on bare MDF, but it seems to work fine for me, so I can’t argue with the results (I was skeptical too!).  I’ve also heard of people using shellac for this step too, with success, it’s up to you.

Finally, we’re ready for sanding.  I started with a quick power sand with 60 grit to knock down some of the high spots.  The glue painting step left some brush marks (not nearly as bad as I was thinking though) so this got rid of them.  Then I hit them with a couple coats of high build automobile primer.  I should note at this point that I do not have any sort of air compressor setup, so all of this is being done by Rustoleum rattle can.  I managed to get two thick coats out of a can of paint, so I stopped there.  24 hours later…You can see some pictures of how they looked at this point, pretty ugly!  There were some MDF fuzzies coming through the paint and some seams showing up.  This is to be expected though, paint really doesn’t cover anything up, it actually accentuates any flaws in the underlying material!  Back to sanding.

I hand sanded with 100 (everything is hand sanded from now on) which did a good job of getting rid of most of the fuzzies, then shot another can of primer on (2 more coats).  24 hours later…Hand sanded again at 220.  At this point they were starting to look pretty good, but there were still some seams and little imperfections.  Most people use a body filler for fixing these, but I didn’t have any on hand, so I used drywall compound (spackle).  Again, people will  scoff at this because it’s water based, but has worked for me in the past, so I’m all for it.  24 hours later…sand the spackle smooth.  You can now see a couple pictures at this point, much better!  Very smooth now and almost ready for paint.  Another can of primer and 24 hours later I sanded to 400.  Looking very nice now, ready for some paint!

I’m using Rustoleum flat black paint.  The paint setup, as you can see from the picture, was a bit interesting, but it worked out OK for me.  I got about 2.5 coats of paint per can, so the fronts and tops got a little more than the sides and back.  After the first can I let it dry 24 hours, then scuffed it perfectly smooth with some steel wool, cleaned it up with some tack cloth (be careful with hand oils at this point) and started the real painting.  I put coats of paint on every 15 minutes for an entire afternoon/evening, so I would say there are probably 12-15 coats on there.  The color came out very even, no streaks or stripes.  There is a little bit of texture to it that you can see in the pictures.  This is due to the quality of the spray cans probably, but I don’t mind it too much.  If you were going for completely flat you could do some color wet sanding at this point.  I don’t really see any need for this as nobody is going to be inspecting them that closely.  As you can see from the pictures I didn’t go crazy with the backs.  Nobody is going to see those anyway, so I figured I was just wasting my time.  I concentrated on the fronts and tops and they came out very nice and even.

Overall I am very happy with them.  They blow my old cheap speakers out of the water and I think make the desk look great.  I may just do a sub next, we’ll see!

Next I went ahead and got started cutting out the baffle.  The M3N is designed to be flush mounted, so I had to cut a recess in the front baffle first.  The jasper jig makes that extremely easy to do.  I highly recommend one of those things if you plan to be cutting circles.  After the recesses were cut I cut the driver holes and the tweeter holes.  The ND20 tweeter ended up being a really odd size, between two sizes on the jasper.  I could have either cut the hole slightly too small and sanded the rest of the way, or slightly too big and leave a little gap.  I decided to cut it slightly big because I thought the paint may build up the sides a little bit as well.  I think I ended up using the 1 7/16″ hole size.

The final work on the baffle was making sure everything fit!  I had to cut out little notches on the driver holes to account for the little wire terminals, which wasn’t too big of a deal.  Then I checked for fitting and it all looked good, so I drilled the holes for the mounting screws and rounded over the back of the hole.  This apparently is fairly important in directing the sound inside the cabinet, so that it doesn’t just get directed straight towards the back wall and cause bad reflections.  I mounted the tweeters with a few screws, wood glue, and sealant (they aren’t going anywhere!) and on the left you can see the completed baffles!

Just as I did with the rest of the cabinet, I cut the baffles about 1/8″ large all the way around and used a flush trim router bit to get them nice and perfect.  You can see the before and after picture on the right.  That flush trim it is awesome!  I wish I had it when I was building the garage system.  It would have saved me a lot of paint prep work.

The final construction step was to round off the sides.  You can see the completed, unfinished cabinets on the left.  They came together really nicely and I like the look of just the sides rounded over.

I started on the paint prep work last night by sealing up all the cut MDF edges with standard white Elmer’s glue.  The cut MDF edges tend to soak up paint like a sponge, so this should hopefully help minimize that.  I’ll probably start doing the rough sanding tonight and maybe get these ready for painting by the weekend.  The last set I did in a semi-gloss black, but they still came out a little too glossy for my taste.  I’m going to try flat black this time and see how it goes.  I’ve seen a couple of others do flat black and they look really sharp, so that’s what I’m hoping for.  It should match the trim on the monitor pretty close as well!

Rendered in Luxrender for about 2 hours with a basic clay material and a couple of light sources.  Enjoy!

I already have a decent headphone amp up there, that conveniently enough has speaker outputs, the NuForce Icon 2.  At 4 Ohms it puts out about 24w per channel, so the speakers need to be fairly small and efficient.  I decided on the HiVi M3N full range drivers which have excellent reviews online.  To give a little more oomph to the setup I’m going with two woofers per side in an MTM arrangement with the Dayton ND20 tweeter.  To begin with I’ll probably use the sub from the existing 2.1 setup.  I also have most of the other crossover components from previous builds, so grand total for parts this build comes to about $75.  Should be a pretty fantastic sound for $75!

The first step is to build the crossovers.  I’m following Wolf’s Switch plans pretty closely, so I’m going to use that crossover design.  Here is the layout on the crossover with one put together and one waiting to be glued to the cardboard.  The cardboard pieces are about 4 x 5 inches, small enough to fit in the planned cabinet.  The next pictures shows both put together, glued up and all soldered.  I connected them to the speakers and tweeter on the bench and they both seemed to work, so fingers crossed when I put them in the cabinets they still work!

The next step is the cabinet.  The drivers are small little things, so the cabinet will also be pretty small.  It’ll be about 6.2 ltrs sealed MDF.  The top, sides, and bottom I’m making out of 1/2″ MDF and the front baffle and back will be 3/4″ MDF to give the flush mounted drivers some mounting room.

Here is a shot of the construction so far without the baffle put on.  It’s pretty straight forward to this point, just cutting and gluing together.  With the Aura monitor cabinets for the garage I had a heck of a time trying to get all of the pieces cut to the same size.  I tried like crazy to do it, but a small difference when cutting creates a 1/16′ or 1/8″ change in size, which when finishing is tricky to sand out (I don’t have a belt sander).  So, for this build I decided to cut everything about 1/8″ large on all sides and flush trim them with a router.  Worked wonders!  They look great so far.

The front frame that the baffle will mount to wasn’t perfectly flat, (because of said difficulties cutting) so I needed to come up with a way to make all the faces flush.  It would be fairly easy if I had a router table, but no dice there and I don’t really have the room to put one up in the garage anyway.  I decided to build my own temporary router table, which came out OK despite the thrown together nature of it.  The table is made out of a piece of 3/4″ MDF mounted to the base of the router with a few long bolts.  It was pretty lopsided, so I stuck a cinder block under the other side of the base and clamped a quick fence to the side and cinder block together.  I threw it together in less than an hour, with parts around the garage, so all in all I’m happy with it.  It worked pretty well too, so I think I’ll keep this piece of MDF.  Next time I may flush the bolts into the top though, they sort of got in the way while cutting as the heads are pretty large.

The next step is cutting the holes in the baffle and then testing everything out before I seal it up.  Judging by the looks of the backs of the M3N and ND20 they may require some fancy cutting, but I’ll keep you updated!

While I was waiting for paint to dry on my stereo system I decided to test out some ideas that I’ve had for the next rolling ball sculpture.  My previous two pieces were both done in all copper, which I think was a good introduction into the RBS world.  Now that I’ve gotten the basics down, for my next piece I didn’t just want something that was functional and kind of cool to play with.  I want to make something that people look at and say, “Wow, that thing is so cool!”  After searching around and looking for some interesting materials I decided on brass as the track material.  I also wanted to use the bigger shooter marbles with this one, so I needed something a fair bit thicker than the flimsy copper wire I was using.

I picked up a couple of 12 inch long, 1/8″ brass rods from a local hardware store and set to it building a short little test track.  I was much more analytical in my approach this time around regarding the track width.  Previously I just sort of made sure the marbles wouldn’t fall through the track and went with that.  I came across this site and figured out a fairly exact track width for my marble size.

One more thing I really wanted to do with this one was use more impressive track spacers.  The little roller coaster type ties I was using before did their job OK, but didn’t look that cool.  They were also a pain to make/install.  After doing some research online as to what people are using I decided on using complete circles for the spacers, kind of like little tunnels.  I was amazed when I saw this technique in the movie Fracture and think the effect is much cooler than just a straight track.  I can also vary the width of the spacers to create even longer tunnels/tubes.

After doing a lot of calculations and researching available materials I couldn’t find any brass tubes/washers that would work how I wanted them to.  I decided on using copper for the spacers, which I actually think gives a nice contrast with the brass and looks pretty good together.  Unfortunately, with the marble size and the track needing to fit through the spacers, 1″ standard copper pipe was too narrow.  It was also really expensive!  I searched through the plumbing aisle at Home Depot and found the straight barrel 1″ copper pipe fittings.  Now, because they are made for 1″ copper pipe to fit inside, they are just a tiny bit larger than 1″ and fit the track and marble perfectly.  When I say perfectly, I mean the marble makes it through with probably less than 2mm of space at the top.  I just have to make sure that any other marbles I get are the exact same size.  I quickly soldered the track to the insides of the track spacers at the correct track width and have a nice working section of test track to play with!

I’m super excited about how this thing looks.  The brass track looks amazing and has a really cool sound to it.  It sounds really solid, much different than the thin copper wire.  It was quite a difference working with 1/8″ rod instead of the thinner copper.  I was still able to bend it by hand, but had to use some real force.  I shouldn’t have to worry too much about it taking a knock and getting out of line like before.  This thing is sturdy!

So I have most of  the bits for the new sculpture, I just have to figure out how I want to overall thing to work.  I’m thinking of a motor lift on this one, hmm…

The little amp is mounted inside the box with the controls stuck out the front panel.  I had thought about mounting the knobs and switch to different places on the top panel, but they were all surface mounted to the board inside the amp.  I didn’t really feel like unsoldering everything and adding extension wires, so I just used the front panel of the amp for a template and cut those holes out of the front wood panel.  It turned out pretty nice actually and the volume knob still glows blue.  I may look into adding blue lights to the tuner to match, instead of the old yellow-ish glow that it puts out.

All in all I’m super satisfied with the sound that it is putting out.  Those 3″ little woofers are really great, it sounds like a full home theater system.  I’m constantly looking around thinking that someone added a sub without me realizing it!  The vintage tuner is also really cool.  That huge tuner knob in the front is so smooth.  I wish new electronics were made up to these specs!

This project started out as just a way for me to get some music back into the garage while I did my rolling ball sculpturing, but it’s really piqued my interest in DIY audio systems.  I may just have to make a system to replace the cheap PC speakers I have on my desktop computer!

My first step was to pick up a few components.  I wanted to spend as little as possible, but also make something that sounded fairly decent and also looked pretty good.  My requirements for the system were pretty basic; I wanted an am/fm tuner, iphone hookup, and some bookshelf speakers.  I could have just bought a little iphone alarm clock, but I figured I could make something that sounded twice as good, for a lot more fun!  Those little alarm clocks are like $70, so my goal was to spend less than that.

For the speakers I went with 3″ Aurasound NS3-193-4A’s.  They have some excellent reviews and with the wide frequency range I wouldn’t necessarily need to run tweeters or a sub with them.  I picked them up for $12 each, score!  Subtotal = $24.

For the amp I went with a T-class Lepai TA2020.  It’s pretty cheap, but does a decent job.  It also has both RCA and line-in jacks, perfect for my needs.  I picked it up on sale for $15.  Subtotal = $39.

Finally, for the tuner part I love the look of the old vintage tuners with the huge dials, cool lights, and cool little signal meters.  In one of my best ebay buys ever I grabbed a Kenwood KT-6500 for $25.  Grand total = $64!

I built up the speakers this past week (sorry for the bad phone pictures).  They are in 5 x 5 x 5 inch internal sealed and stuffed enclosures.  The boxes are made out of 1/2″ mdf, screwed and glued together, then sealed with silicon on the inside.  I did a nice little routered edge on the front baffle, then sprayed them with a few coats of semi-gloss black.  The finish came out really nice actually.  I did a fair bit of sanding and finishing, but seeing as though they are just going in the garage I didn’t go too over board with it.  There are quite a number of little imperfections in the paint, but I gotta say I really like how they turned out.

I hooked them up yesterday to the amp and my iphone and they sound great!  These little guys easily sound better than my 2.1 setup at my computer and probably also beat out the setup I have in the living room.  I may up building a system for the living room too, these are amazing!

The tuner should be here in a few days, so I’ll let you know how it all sounds together.  You can see the little amp in the corner of the first picture.  I want to build a nice little enclosure for the amp and tuner to match the speakers as well.