Archive for the 'Electronics' Category

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SteamBox Build

I haven’t been a PC gamer for years. I spend all day at work sitting a computer desk, I spend a lot of time at home sitting at a computer desk working (to keep my various websites running) so when I need some down-time I’d rather sit on my couch and play games then spend even more time at a computer desk…


A few months ago Valve introduced “Big Picture Mode” for Steam. This mode basically adjusts the Steam menu system for HDTVs and controller based navigation. Rumors started flying that they were going to make their own console to compete with Playstation and Xbox. More recently those rumors were somewhat confirmed when Valve announced that they will be making a “SteamBox” spec for what this Living Room PC should be, essentially allowing any hardware manufacturer to make their own variation of the SteamBox and at the same time help standardize the PC; the first of which is the Xi3 Piston.


This obviously intrigued me since there are a number of PC games I’d love to play but not wanting to drop $1000+ for a gaming PC and then spend even more time in my office playing it. So I set out to build my own budget SteamBox. The SteamBox “spec”  hasn’t been released, though chances are it would be out of my price range anyway so I was just going to see if I could get the job done for under $300 (what I’d expect to pay for a console) leveraging the piles and piles of old PCs I had laying around.


The first PC I was sacrificing was an old HTPC/DVR I built, after looking at the equipment inside I quickly determined that the only thing worth salvaging was the case itself and the disc-drive. The case was an nMedia HTPC 600BAR. It’s a nice black steel chassis that supports a full-sized ATX Motherboard with a real brushed aluminum front, an integrated IR window, as well as flash media ports right on the front and a decorative disc tray door. (it’s also got USB, Firewire, and audio ports on the side right near the front). The DVD R/W drive is nothing special but it’s compact, quite and supports SATA.

The second PC I salvaged was one that my brother gave to me. I had built it for him 2 years ago for HD Video editing. it was blue-screening on him every-time it booted up and he got frustrated and just bought a new PC and gave me his old one since I had built it. This had an Asus P5N-D motherboard which is setup for gaming with overclocking features, it had a Intel Core 2 Quad (Q6600) processor 3GB of DDR2 memory across two sticks, and a two Seagate Barracuda 320GB 7200RPM SATA drives setup in a RAID array. It had a really nice Rosewill 550W power supply and a good-for it’s time but now dated ATi graphics card along with various other bits of essentially uninteresting hardware.

Comparing the specs of the Q6600 to an Intel i3 I found them to be fairly comparable CPUs, the i3 was more efficient and slightly better for gaming tasks, but the Q6600 was a slightly better performer for non-gaming tasks. So I considered this a good-enough platform for my needs… I don’t need a graphics powerhouse and my projector is only 720P so as long as I can run games above 30FPS at 1280×720 with decent AA and textures I’ll be happy with the results. Sure an i3 would be a bit better and an i5 would be a big step up… but the Q6600 was free and that would give me a lot of room to work with the rest of it.


Since I was short-changing myself slightly on the processor side I wanted to get the beefiest graphics card (I could afford) that was compatible with the somewhat dated motherboard. the P5N-D includes 2 16x PCI-e 2.0 slots (3.x is the current new standard) looking around there were a few $400+ cards that still supported the v2.0 slot but the GTX550 seemed to fit my needs, it has an HDMI port (an absolute must for a TV build) and I found a used “superclocked” variant with 2GB of on-board memory for $120, I probably could have found. The next step up used  v3.0 and the 2GB variant of that was prohibitively expensive so this seemed like a good choice. I also picked up two used 2GB sticks of matching DDR2 memory for $25 to max out the motherboard supported of  8GB of memory.

If you’re keeping track at home I’ve spent $145 including shipping and my PC specs are:

  • nMedia 600BAR HTPC Case
  • Asus P5N-D Motherboard
  • Intel Core 2 Quad Q6600 processor
  • 8GB Corsair DDR2 memory
  • nVidia GTX 550 Ti 2GB Superclocked
  • Seagate Barracuda 320GB 7200RPM HDD in RAID array
  • Rosewill 550W Power Supply
  • Lite-On DVD R/W drive
  • integrated flash media slots

Now came the came the part where I’d need to chose an operating system. Ideally I’d run Ubuntu but that’s not really an option for gaming. Rumor has it the official Valve SteamBox will run Linux, which is great and I’m sure that will vastly improve linux gaming support, but the market is just not there yet. I like Win 7 but I’ve heard that Win 8 is a little lighter and runs a little faster, not to mention the Metro UI while loathed by traditional PC gamers seems the perfect interface for a HTPC Gaming machine… Win 8 was the easy choice.


The Last piece of the puzzle is the peripherals, I have a wireless keyboard and mouse that I bought so I could use the keyboard with my Xbox 360 before they released the “chat pad”… it’s USB based with it’s own 2.4GHz transmitter. Keyboard and mouse are a necessary evil but I really don’t want to be using that very often, especially not from the couch. after some research I found there are these generic chinese IR remotes sold under a dozen different names that emulate a keyboard and mouse. The one above I bought on Amazon for $7.50 shipped. It’s pretty slick you can move the mouse pointer around using the big directional button and most of the other buttons are mapped to standard keyboard shortcuts. The best part is that the Harmony Remote supports this protocol so anything you can do via keyboard I can do via my harmony remote.

The first one I received had a defective IR receiver, but the Amazon seller sent me another one without any hesitation. I had to rig up a custom mounting bracket to hide the receive behind the IR window in the front of the case and I even had a USB pin header adapter so I’m not even snaking the cable out to an external port… nice and clean.


The last peripheral bit was to pickup an official Microsoft “Wireless Gaming Receiver” a small USB dongle that allows you to use any wireless Xbox 360 controller on a PC. Sadly I wont be able to easily mount this inside of the case as I will need access to the sync button. I considered doing something clever like cracking it open and re-appropriating the case’s reset button for sync but then I might still run into problems with the metal chassis interfering with the signal… so outside the case it will stay, I may make up a custom mount to keep it at the back of the case.


You may notice that there is another PCI card in there, this is simply a second network card. The reason being is that I had been using another old PC as a hardware firewall for my Xbox 360, this allowed me to force block people on Xbox Live, I’d remote into that PC and identify the IP of the person I didn’t want to play with and add them to the block list. I’d then never connect to them in-game again. It also worked the other way where I could set a white list so I would only connect to my friends, keeping randoms out or forcing myself onto a specific Xbox Live server. Now that I’ll have a PC in the same room as my Xbox I can use this for the firewall tasks and simply switch inputs on my receiver instead of involving my laptop to remote into the old firewall PC.

I haven’t tested it out yet (two of the fans in the case seems to be on their last leg so I want to replace those before I put it through it’s paces… I’m pretty happy with it so far and will be interested to see how my sub $300 SteamBox works out.

Speaker Color Change White to Black

3 Years ago I got a deal on some Cambridge SoundWorks S305s to help round out my 7.1 surround sound system. Normally they sold for $300 a pair but I got them for $100 a pair on clearance. Part of the reason they were so cheap was due to the fact that they were the less desirable white color.

They’ve been sitting in the box since… I finally go around to painting them and re-upholstering the grills.

Today’s Productivity…

… finished building a Tube Based Headphone amp for Jeff

Bought myself a DSO Nano V2 today

I’ve wanted to add an oscilloscope to my electronics toolbox for years.  I’ve passed on a few projects simply because I wouldn’t be able to complete them without one. Well there are a few electrical loose ends to tie up with my LS1 swap so I finally bit the bullet and bought a DSO Nano. Much to my surprise they’ve releases a V2 of the hardware that’s even prettier than the original.

My two biggest apprehensions to buying this were that it only supports up to 1MHz frequencies and that it only has 1 channel. Ideally I like 100MHz and 2 channels at minimum but it was only $90 including shipping, which is a friggin STEAL for a digital capture scope, never-mind one that’s hand-held.

I was almost persuaded to belay the purchase again when I saw on SeeedStuio’s website that they’re taking pre-orders for the Beta version of the DSO Quad.

The Quad has 4 channels and supports up to 36MHz which makes it a huge improvement over the Nano and the pre-order price for the beta test is only $150, but the “estimated” release date is late March. Having the Nano will be an enormous improvement over not having a scope at all, and the Quad is cheap enough that I’ll wait until it’s out of Beta to buy one.  Either way, I’m stoked to finally have an oscilloscope at my disposal again, since I haven’t had access to one since college.

Arcade Control Panel

So recently it was announced that they’re releasing a Tournament Edition of the new Mortal Kombat game due out next year.

As a long time Mortal Kombat fan this is obviously something I’m excited for, I’m even more excited since it’s an all new developer making the game and they seem to be making it a true sequel to the original 2D trilogy as opposed to continuing with the 3D mess that the MK series had become.

The Tournament Edition has me really excited because, well it’s a CE, which I love, but it’s also going to be limited to only 20,000 copies. The biggest thing about this CE is that it includes a Joystick as the main bonus item.  I’m making this post because it seems that a lot of people fail to realize how much of the “real deal” this included joystick is.  Allow me to demonstrate.

Here is a photograph showing the joystick included with the Tournament Edition:

Take a close look at the controls, that is a Happ Ultimate Joystick and Happ arcade buttons with Cherry micro-switches. I worked in arcade repair for several years, nearly ever arcade machine from the 2D Mortal Kombat era uses these joysticks and these buttons…

Need further proof? Take a look at these pictures:

That is an actual Ultimate Mortal Kombat 3 arcade control panel, it’s a conversion machine but those are the buttons and sticks included with the kit from Midway. I wired this control panel myself, and this machine is sitting in my game room, and those are two Happ Ultimate joysticks and Happ buttons with cherry microswitches way back from 1995.

SR5 Cluster

The battery kept dying in the pickup, I determined it was from the aftermarket tach installed by the previous owner so I decided to install the SR5 cluster I purchased.

Installation was tricky because I had to swap odometers with my old cluster so that the mileage remained correct, Also this new cluster was out of a vehicle originally equipped with a V6 and my truck has an I4. This mean that the tachometer needed to be re-calibrated, thankfully I could use the aftermarket tach to “tune” the new one.

Above, you can see the adjustment potentiometer. No one else (to my knowlege) has ever published the adjustment value for the I4 engine, I found lots of people asking online but no answers. So after I adjusted mine I was kind enough to pull out the gauge and measure the appropriate calibration value.

The 3 circled screws on the left image need to be removed, once that’s done the the two locations on the right can be measured for resistance. The original V6 was tuned to 44.9K ohm, and I tuned the I4 to 63.8K ohm. It will likely vary  from vehicle to vehicle but the most important take away is that it’s a difference of ~19K ohm.

crappy pics I know but I think it’s a big improvement.

Only thing left to do is swap over the oil pressure circuit I got a new sensor since the old one was just an on/off switch for the idiot light. the new cluster has a pressure gauge. I bought a new sensor too but the electrical connector is different so I’ll need to swap that too before the gauge will work.


Tore out all the “poorly implemented” wiring in the pickup but I found myself with a number of electrical connectors that weren’t hooked up to anything. The Factory Service manual doesn’t show these… anyone have any guesses? I’ve figured out all the blue connectors, it’s the white ones I don’t know about.

LS1 S14 Wiring

Here are a bunch of photos for the wiring harness conversion, it’s a lot more simple than it looks, if you can wire a car-stereo than you can do an engine harness, there are just a lot more wires and you need to do a bit more digging to determine what goes where.

Bose 901 Speaker Restoration

I’ve posted up a new hack page detailing a the Bose 901 Speaker Restoration that I recently completed.

Bose 901 Series IV Speaker Restoration

Bose 901 Speaker Restoration

Last spring I happened to come across a set of old Bose 901s for sale in the marketplace of my local car club… At a price of $25 including the equalizer unit I couldn’t pass it up. I contacted the seller and met him the next day in Manchester to pick them up.

For those of you unfamiliar with the 901s they’re Bose’s Flagship Stereo speaker set and they’ve been essentially the most expensive set of Bose Stereo speakers you could buy for the last 50+ years. They still sell them today, although they’re on “Series VI” now. New a set of Series VI retails for around $1400. Honestly the design of the 901s has barely changed save for the electronics in the “equalizer” module. The cabinet design, drivers, and wiring in speakers themselves haven’t changed functionally since the Series III.

I’m not a huge fan of these speakers but I bought them because my Father is, I really have no need or room for a set of 901s in my house but I figured I could fix up these speakers and it would make a nice Gift at some point.

My father had a set of 901s (Series V I believe) a number of years back and loved them, I remember he always talked about getting a pair way before then, and he was extremely happy when he was able to finally afford a set. Though about 2 years ago he had to sell them. So you can understand why I wasted no time to pick up such a cheap set of easily restored 901s.

What I started with:

Being a Series IV (which sold new from 1978 through 1982) the cabinet style, though functionally identical the series VI (which was released in 1987 and has not changed since) does look quite dated in terms of the grill fabric and cabinet color.

Bose 901 Series IV

Bose 901 Series IV

Removing the Speaker Grills:

Obviously the first thing I did before I could attack the innards was take the original grills off.

Bose 901 Series IV Speaker Restoration - Grills

The front grills are held on with 6 staples, 3 down the left and right sides. They were somewhat difficult to spot. I’ve circled it in the above picture.

Bose 901 Series IV Speaker Restoration - Grills

I started by hammering a cheap screw driver under one of the staples to pop it out a little.

Bose 901 Series IV Speaker Restoration - Grills

I then used some vice grips to yank  the staple out completely.

Bose 901 Series IV Speaker Restoration - Grills

Once the first staple was removed I had enough room to get my hand behind it so I just ripped the rest of the grill off by hand.

Bose 901 Series IV Speaker Restoration - Grills

The front grill frame is made of particle board so the staples ripped right through it, but it doesn’t really matter because I wont be re-stapling it. Once the grill was off pulling out the rest of the old staples with the vice grips was easy.

Bose 901 Series IV Speaker Restoration - Grills

The rear grill was simply attached with some tree-sap like glue, pulling it off by hand was a breeze.

Parts, Costs, and Planning:

Once the Grills were off I could get a good look at the drivers, time had not been kind to the foam surrounds. All of them were rotted, and some had fallen off of the drivers completely.

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

Looking closer at the drivers the cones, dust-caps, and voice coils all looked to be in great shape, it was just the foam surrounds that were decaying.

Parts Express sells kits to replace various components, you can buy dust-cap replacement kits, foam surround replacement kits, and if the drivers are so far gone you can even buy replacement drivers.

Bose 901 Series IV Speaker Restoration Parts Express Foam Surround Kit

The kits I needed run $35 a piece and I ordered 2 Bose foam surround repair kits (10 foam surrounds per kit) to replace the foam on all 18 drivers (yes 9 drivers per speaker, each driver is <1Ohm and they’re wired in series). There are other kits available elsewhere for less but I know and trust Parts Express having ordered many times from them in the past.

The only other thing I needed for this project was fabric. Parts Express also sells Speaker Grill fabric but I opted to find some locally. I discovered that my local JoAnn Fabric store sells “Speaker Grill Cloth” for $10 a yard. They were having a 40% off sale so I bought 3 yards for $18 since there are some other projects that I would like to have the fabric for.  Considering the width of the fabric you could easily get away with Just 1 yard for the 901s if you planned your cuts right.

Total cost of these speakers was ~$100 not counting disposables such as razor blades, hot glue, and sandpaper.

Driver Removal:

The first thing I did was remove all the drivers (3 bolts each requiring a 1/4″ socket).

I was somewhat shocked when I pulled out the first driver to discover that they use wire wrap for all the internal electrical connections.

Bose 901 Series IV Speaker Restoration - Wire Wrap Driver Connections

I’d never worked with wire wrap connections before. It seems most electronics had abanoned it before the 80s since the only arcade machines I’d ever seen use them were the extremely old pinball machines from the 50s. even those from the 60s and 70s had moved on to more modern connector techniques.  I also discovered that it was difficult to remove old wire wrap without fitiguing and breaking the wire.

Bose 901 Series IV Speaker Restoration - Wire Wrap Driver Connections

Since I don’t own a wire wrap tool, I decided that I wouldn’t worry about it and would rather just go with a spade style connector or soldered connections when I put the drivers back in. Based on what I’ve read elsewhere it sounds like the newer series 901s use soldered connections anyway.

To ensure I put everything back the way it should be I numbered each of the drivers and each of the mounting locations, I also labeled the wires in the cabinet to ensure I didn’t reinstall any of the driver’s backward.

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

While I was in there I decided to map out the internal wiring. A quick search on google turned up this diagram:

Bose 901 Wiring Diagram

The text listed with the image stated that it was the diagram for the Series II and Series III revisions, I would tend to believe it as it did not at all match the wiring I found inside my pair of Series IV speakers. I’d read that the Series IV through VI used similar wiring. Using the diagram above as a starting point I modified it to reflect the wiring found in my Series IV.

Bose 901 Wiring Diagram

The yellow wire at attaches to the #9 driver goes to the “*” terminal on the outside of the speaker. I’m not sure what this terminal is used for but the labels on the speaker cabinet state not to use it.

Driver Cleanup and Prep:

Before I can do anything with the drivers they need to be cleaned up. All of the old decaying foam surround material needs to be removed and the surfaces cleaned and ready to glue on the new foam.

First thing I did is pull off as much of the rotted foam I could with my hands. Once the bulk was removed I used a razor to cut off as much of the old glued foam as I could,  a fresh blade with sharp edge and the right angle and you can strip it off without much issue. I went over the glue foam on the cone 2 or 3 times taking off progressively more each time, as a paper cone it is extremely delicate so taking your time is preferred.

Bose 901 Series IV Speaker Restoration

Next I used a small screw driver to scrape the old glue off the basket.

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

Once all the material had been removed I rubbed my finger over the foam on the cone to loosen up and brush off any dust or small particles that remain. Then I went over the whole thing with compressed air to remove any particles left, taking caution to make sure there isn’t anything under the cone.

Finally I went over the basket surface with isopropyl alcohol to make sure it’s completely clean, I don’t do this on the basket surface as it could damage the cone.

Bose 901 Series IV Speaker Restoration

Now I have a nice clean driver ready to receive a new foam surround.

Bose 901 Series IV Speaker Restoration

Installing the Foam Surrounds:

I started by placing a bead along the edge of the cone as well as one along the inside edge of the foam surround.

Bose 901 Series IV Speaker Restoration

I used the swap to spread it out a bit, I did a little more after the above picture was taken, you want a nice thin, even layer over the whole area to be glued.

You should let the glue “set” for 5-7 minutes before attempting to stick the two sides together, it turns clear when it’s ready. Most of the time I found it was easier to know when it was ready by the clarity of the glue rather than some arbitrary amount of time.

Centering the foam surround is CRITICAL. the cone sticks up past the basket slightly, so I placed the ring, then pushed the cone down slightly and made sure that the ring is centered on the basket, then when I relieved pressure on the cone it would center itself.

Bose 901 Series IV Speaker Restoration

After that I went around the edge of the cone applying pressure to ensure good adhesion.

Only the center part of the foam is glued at this point. It needs to setup for at least an hour before the outer edge of the surround could be glued. To be on the safe side I let them sit over-night before continuing.

Once the glue has dried on the inner portion of the surround I could begin gluing the outer edge.

I started the outer edge by first running a bead along the flat surface of the basket.

Bose 901 Series IV Speaker Restoration

Then I put a small amount of glue under the edge of the foam surround, this is a pain since you have to peal the foam up with your hands and spread the glue over a small section at a time until you’ve gone around the entire edge.  This is also why you need to let the glue on the inner edge completely dry before attempting the outer edge; the stress of pealing up the foam could compromise the adhesion on the inner edge.

Bose 901 Series IV Speaker Restoration

Once the glue has been placed I used one of the included swabs around the parameter smoothing and evening out the glue on both surfaces.

Bose 901 Series IV Speaker Restoration

Like the inner edge, I let this set for 5-7 minutes before affixing both surfaces, they wont touch since the cone naturally sits up higher than the basket.

Centering the outer edge is perhaps even more important than centering the inner edge. The reason being is that any mistakes made on the inner edge can be corrected with the outer edge, so there is no room for error.  If not centered properly the cone will not be able to move up and down smoothly and the sound quality with be severely diminished.

To ensure it’s centered I used a bottle of water, with just enough water to push the cone down without crushing it. The water also ensures that it’s being pushed straight down and perfectly centered. My kit didn’t come with any, but some other kits include shims to help ensure that the cone is properly centered during this step.

Bose 901 Series IV Speaker Restoration

Again I go around the parameter applying pressure until it’s affixed well. I leave the bottle on the cone for a minute or two to let it settle to ensure that the foam doesn’t pop back up.

Bose 901 Series IV Speaker Restoration

The glue should dry for at least an hour before you reinstall them. Keeping them on their backs while they dry will help ensure good adhesion.

Reinstalling the Drivers:

I looked into various spade connectors that I could use to hook the wires up to the drivers but alas I couldn’t find any that were worth using. Without the proper tool to do wire wrapping I ultimately decided to just solder them back together, I don’t really plan on taking these things apart ever again so I might as well. Reading around I get the impression that the Series V and VI use soldered connections on the drivers anyway.

I started by ensuring I had straight/stripped wire ready on each connection, I used a slight bit of sand paper to take the dust and coating off the wires, they have a coating to prevent oxidation but it also hinders soldering (since it was designed for wire wrapping) just a light sanding is all that was needed to ensure that the solder will stick well.

Bose 901 Series IV Speaker Restoration - Soldering

I did the same on the drivers, only I used a screw driver to scrape it off since it was much thicker and heavier on the wire posts than on the wires themselves.

Bose 901 Series IV Speaker Restoration - Soldering

I tinned both the posts on the drivers and the wires.

Bose 901 Series IV Speaker Restoration - Soldering

Once everything was tinned I soldered each of the driver’s connections, tore off my wire markers (I wouldn’t want them buzzing inside the speaker once it was all back together).

Bose 901 Series IV Speaker Restoration - Soldering

After soldering each driver I bolted them back into the cabinet before starting to solder the next. I also re-used the original foam isolator that goes between the driver and the enclosure, these were still good and they keep the drivers from buzzing or rapping against the enclosure.

Since the wires were short I did the bottom row of speakers first, then flipped the enclosure upside down and did the other row, it saved me a 3rd hand.

Bose 901 Series IV Speaker Restoration

Bose 901 Series IV Speaker Restoration

Once the speaker has all the drivers back in place it is functionally restored.

At this point I tested the speakers. They sounded great but I did notice that one of the terminals was lose, so I pulled out the nearest driver so I could tighten the screw on the inside.

Bose 901 Series IV Speaker Restoration - Testing

Grill Cleaning and Prep:

Now that the speakers were functionally restored, all that was left was to make them look a little more up to date. I decided that the wood coloring wasn’t all that bad, and while the cabinets had some scuff and scratches my wood finishing abilities have something to be desired. In the end the only updating I would do is the grill cloth, replacing the ulgy Tweed with some new, more modern black acoustic fabric.

Before I could do anything though I had to strip down the old grills to their bare frames.

I started by removing the push pin badges from the front grills.

Bose 901 Series IV Restoration - Grill Badge

The fabric on the front grills was easy to remove just pulled it off with my hands and spayed it with some compressed air and they were ready for new fabric.

Bose 901 Series IV Restoration - Grill

The rear grills needed a little more work before they would be ready for fabric though.  I used a razor blade to separate the plastic port hole trim pieces from the grill, then pulled the material off by hand just like the front, then I used a razor to clean up all the large glue bumps left around the port hole areas.

Bose 901 Series IV Restoration - Grill

Unfortunately there were little bits of tree-sap glue as well as tweed “fur” stuck all over the grill frame to the residual contact cement.  To get rid of this I took a block sander and sanded it down to remove all that. Then I dusted it with a damp rag then once dry I went over it with compressed air for a nice clean and smooth grill frame.

Bose 901 Series IV Restoration - Grill

Grill Re-Upholstering:

Now that the front and rear frames were prepped they were ready to be reupholstered. I’m not much of a fabric person so I just did what made sense to me, overall I was pleased with the outcome though.

I started with the front grill. I laid the grill down on top of my fabric and cut around it so the fabric stuck out roughly an inch around the parameter of the frame.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

Normally acoustic fabric is installed using a spay on contact cement.  I really hate working with that stuff, and acoustic fabric is stretchy in all directions, so I decided I would just work my way around with some hot glue. It worked exceptionally well. After each tack I’d check to ensure I wasn’t introducing any wrinkles on the other side.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

After I was done gluing I went around and trimmed off all the excess material.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

Finally, I put the badge back in place though the original hole to complete the front grill.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

For the rear grilsl I started by cutting, gluing, and trimming the fabric just like I did on the front grills.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

Once the fabric was glued and trimmed I cut an X one of the port hole areas with a sharp razor.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

I then pressed the port hole trim through, checked for wrinkles, and trimmed up the excess fabric.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

After that I hot glued the trim ring in place (which also helped secure the fabric around the ring as well). Following that procedure for the rest of the port hole openings the rear grills look nice and neat when done.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

Once all 4 grills had be reupholstered I hot glued them back onto the enclosure. I figured this would be more visually appealing than re-stapling the front or finding some kind of replacement glue for the rear. Hot glue holds securely but can also be easily pulled off if need be.

The front grills were tacked in six spots where the staples used to be.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

The rear grills were tacked in ten spots where the “tree-sap” glue used to be.

Bose 901 Series IV Speaker Restoration - Grill Reupholstering

The Results:

Overall I’m quite happy with the results, with a few days worth of work and relatively little money spent I ended up with a nice looking and nice sounding set of classic stereo speakers. Hopefully they’ll seem some good use in years to come.