Introduction: Retro Art Deco Radiogram Surround Sound Cinema Speaker
Grand Prize in the
Audio Contest 2017
This is a surround sound speaker cabinet to house various speakers required for 5.1 surround. There are 2 rear speakers behind the camera not shown.
Iv'e always liked the designs of old radiograms and old radios so I did some research and came up with a few sketches/combinations.
This is all work in progress, I'm not a joiner, I'm not an electrician, I'm not a sound engineer, etc, it is a bit rough around the edges so please don't criticise if your standards are far superior to mine. It was built for fun. Frankly I'm amazed that I got this far.
This Instructable is more of a guide for your ideas than an outright detailed 'how to'.
The speakers I already had for my surround sound consisted of old hifi speakers, car speakers and a home made subwoofer I made from design plans I purchased off the net.
The rear speakers are not really seen but the front ones are always on view, along with wires and extra amplifiers. So whatever I made it needed to look simple and cool and hiding as much untidy wiring etc. as possible.
Step 1: Research - Art Deco
I saved loads of images from the people generous enough to place them on their websites, as well as on the usual auction sites. The ones shown are a tiny sample. I used these as my main influence.
The USA blogs and auction sites are particularly good for research.
I preferred the curvy designs though I realised that this was going to add a lot of time to construction.
The current design is still not finished as I keep thinking of new things I want to add or improvements.
Step 2: Final Design
I made a lot of sketches with various influences and eventually stuck them in a book. Some examples are shown.
I ended up with quite a few ambitious designs that I don't have time to construct at the moment.
The one chosen was, I thought, an achievable starting point.
I used photoshop a few times to combine research designs, the final photoshopped design is shown. I'm not claiming this design to be original, these are the research designs that stuck in my mind so I trusted that they were for me.
The whole thing has to house a large subwoofer, 2 car speakers, a centre speaker(s), some lights and an amp for the subwoofer.
I wanted a logo light feature to glow in the dark when watching films. you can see it in the image above but it actually came to be added after construction had already started.
Step 3: The Basic Frame
Because the subwoofer is so large the dimensions of the case had to be based around that.
This was fine as its height was about right for the projector screen.
I made 2 frames sides, shown in blue. These were to gauge what width and depth to go for. I could still change my mind at this stage.
The four pieces of wood for the width between is shown in red, became 32 inches.
The height is also 32 inches.
The depth of 18 inches had to allow room at the back for a subwoofer amplifier and supply sockets.
Once I had this basic frame over the subwoofer I checked to see if it worked. the back part made the structure more rigid.
The last picture has a first coat of wood effect primer on it which is mentioned later.
Step 4: The Semi-circle Ends
18 inch curves of ply were used for the frame of the lower base ends.
This bit wasn't easy, it took a few attempts.
Flexible 4mm ply at was bent over a single semi-circle curve in the middle.
A screw held the starting point secure. I then wrestled the ply tight further onto it using a mixture of clamps and/or masking tape. The clamps fell off a few times. You can see that I added screws where I could, these were removed the next day and the holes were filled in.The PVA glue slid and made it swivel/skid a but but I got there in the end.
It looks bad but it worked for me. I don't have a proper workshop yet.
You can also get flexy MDF sheets. But I thought that ply would be more durable in the long run as furniture gets knocked about by kids, hoovers, etc.
Additionally I don't use MDF anymore unless I have to, the dust when sanding and cutting is deadly.
The finished and trimmed semi-circles were then glued onto the inner frame. The fit isn't perfect but thats where car body filler and sanding comes in.
Step 5: The Subwoofer.
I made some PA speakers for my band using plans I purchased from the this guy:
I am not connected with this site etc.
The band speakers were excellent, so when I eventually had the chance of my own mini cinema I bought the plans that make a 'Tabletuba'. I wasn't disappointed.
Inside it has an 8 inch JBL GTO car speaker, larger speakers can be put in.
The only problem is that the recommended speakers were only available in the USA at the time I made it. Maybe its different now, but a little research on the sites forum is always helpful.
I forgot to take pictures of of my Tabletuba before I put it inside. I'm not inclined to take it apart just for images. The centre port vents at the back of the cab and is helped by being near the wall when in position.
Great fun to make. You really do need to read the very detailed plans, more than once. It will save you having to do it again. you get a 3D file too so that you can look around and inside it in Sketchup. Use the right glue suggested, even if you have never heard of it and have 10 gallons of PVA available. If the speaker is not airtight it will not blow your socks of properly. Air leaks may ruin your speaker too. The music and effects in films are now reproduced much better than my local cinema. Music sounds huge and immersive too.
The sub is a bit restricted in this case design of mine, but seems to still work very well. I may put it in another design later but for now its in this and its staying.
Step 6: The Left and Right Speakers.
As surround sound they are not ideally placed being in this Radiogram.
The speakers would actually be better higher on the wall and much further apart.
I could still do this, but I chose not to.
The sketch shows roughly how they are attached to the side frames.
The semi circular speaker grilles restrict the space but it was still fun making the curved cabinets to suit it.
'Fli' 5 inch car speakers go in the front. They sound good and are cheap. I could upgrade later but I am not in any hurry.
The curved boxes are ported at the back with a slot. I'm sure that I could spend lots of time tuning the port but not right now.
Step 7: Front Speaker Grill.
The centre vocal Channel of the surround sound comes out of the front grill section.
The slots were laser cut out after I made the DFX file on a program Called 'Serifdraw' which exports drawings as vectors that a laser cutter can follow.
It is an approximate copy of the grill I liked in my research.
It was cut in 6mm plywood that would fit in the laser cutter which has a bed 600 x 400 mm.
I then glued wood on extra ply on the outsides to get it to the 28 inch square face. Any gaps were filled with car body filler and sanded down ready for painting.
I routed a 10mm radius on the slot corners to smooth them out and look more authentic.
The front and back are shown.
Step 8: The Oak Wood Finish
This is fake wood effect paint. There are plenty of good tutorials on how to achieve a this effect. I used the 'Oak' Brushwood kit (now discontinued they told me in B+Q, luckily I had nearly a full kit in the shed). Others kits are out there.
I would like to have a go one day at recreating the old Bakelite radio effect but this will take time to sort out so thats for much later on and on something else.
You have to be methodical with this method, use masking tape to protect where you don't want it to go or to create fake edges where panels meet.
There is a primer that gives the overall tone as shown in the pictures and then a coloured varnish that you have limited time to apply and scrape using a 'comb' provided in the kit.
The comb you have to rock up and down as you scrape the varnish partly off. Practice on a spare piece of wood first, wipe it off quickly if it goes wrong and re apply, try again.
Four coats of varnish add a bit of depth and durability. I used the water based 'diamond hard' clear varnish.
Step 9: The Grill Cloth
A small frame is screwed to the inside of the front panel both supporting the grill cloth and tensioning it. The fixing screws are at the sides on the vertical frame parts.
To tension the cloth I used the same method that artists stretch canvas onto frame ready for painting. Its stapled on from the centre out wards with 'hospital corners' at the corners. Again this is best seen rather than described. There are plenty to tutorials on the net.
Grill cloths with metallic effects can sometimes have a side that works and one that does not, so look out for this if you purchase any. I got mine from an auction site, yep that one.
Step 10: The Light Up Logo
Using the Serifdraw program again I made an approximate shape of an old logo from the 1930's.
It has an old font and lightening in it so after much research this was the one.
It was laser cut it out of 6mm ply, it was quite flimsy until the resin reinforced it. I routed out the front of the front panel board to sink it in. I used thin ply for this as thicker ply tends to char at the edges
After applying tape to the front and laying it down on a flat surface I filled the laser made cut outs with transparent fibre glass resin.
Unexpectedly the resin warped the tape as it dried and warmed. Thankfully this was fixable. I carefully rubbed the outside face down with 600 wet and dry paper until the raised surface of the resin was level with the surface of the wood.
At the end, when the wood effect paint was varnished, the varnish also filled the pores of the resin making it go from foggy to clear without any further finishing.
Any wood effect paint that ran onto the resin surface during the finishing stages was cleaned off using an automotive fibre-glass pen (shown), the ones used for cleaning metal, rust, coins, paint, etc.
There is a small red LED strip mounted behind to light it up . This powered by a 9 volt plug transformer, even though it is a 12 volt LED strip. I've been finding that a lot of these LED strips are poor quality and burn out after a short time. A lower voltage will provide adequate brightness for this and hopefully a longer life. The strip is hot-glue gunned onto the subwoofer cabinet to allow me to change its position if required.
Step 11: The Curved Speaker Grilles
Here a summary of how I made the grilles.
They are not perfect but they look good and I learned what not to do next time. It took a lot of time.
The 18 inch diameter semi-circles can be routed out using a jig to help repetition, in my case they were again laser cut.
Again Serifdraw provided the file in DXF format for the laser cutter to follow
There is a lot of waste when cutting these shapes out of ply so some tessellation is required, this is dependent of the sheet size.
I made a jig to route the finished edge on the 18 inch curve and then used it to add the top radius of 10mm as before.
The spacers for the gaps are made of 15mm ply, cut out using a 60mm tank cutter.
The 60mm spacer circles were then cut into quarters for the ends and halves for the curves, placed at a third of the distance along.
They were glued using 90 degree corner jig to keep the curves in line on the front curved surface.
They are still a little uneven but unless you look closely it doesn't really matter, its the effect that matters more.
They have been screwed on to the frame, but I may go for velcro or magnets to allow me to take them off and improve things as ideas and materials emerge.
Step 12: The Radio Glass
Iv'e been waiting to use this old glass. I rescued it from a radiogram found in a skip many years ago.
It has some imperfections but is the real thing. It would be hard to replicate, there's lots of detail.
The rest of the radiogram it was attached to was beyond saving. Shame really.
But the 'glass' lives on here.
A rebate was routed out of the front panel, 4mm deep. The glass sits in this held by some small strips of plywood 10mm wide by the full width of the glass. I was careful not to clamp the glass too tight with the small wood screws I used.
The glass is backlit by a warm white LED. The light is diffused by a sanded rough acrylic panel and some non-slip draw plastic over the bulb as in the red light.
Step 13: A Work in Progress
I'm still improving the internals as it was necessary to prototype to find out what went where and if lighting worked where it was thought to be at its optimum.
You can see that I have been trying different types and combinations of speakers/tweeters.
The back panel has been on and off a lot as I change my mind so its not totally rigid as a structure yet.
I need to sort out the grille cloth for the curved louvres to hide the speakers better as I don't want them on show.
This will require a curved internal frame to support /tension the cloth.
Thats it. Visitors seems to like it. It glows with light even when not in use for sound.
I hope that I may have inspired a few people.
We have a be nice policy.
Please be positive and constructive.