Scratch Build – In Progress Project: Wooden amplifier case

The General Plan

The general idea is to make this sonic T amp appear less fugly by transplanting it into a wooden/aluminium case.



The case will be considerably larger then the original in order to accommodate the amps power pack which is normally external. The case will be 12mm KD Tasmanian oak all round bar the base which is MDF. The sides and front will be joined with blind dovetail joints while the back will use a box join style joint. The front panel will have a 186 x 50 inlay of aluminium on which the power LED and Volume/on knob will be mounted. This gives a solid base to bolt the volume control to as well as add a more modern look to the wooden design.

The starting point of this project is the sides and front. They are cut from a plank of 12x65x2400 KD Tasmanian oak then marked up and place in a dovetail joint jig.



Although dovetail joints can be done by hand using a saw and your teeth I have chosen the cheat way out in using a jig. The idea of the jig is to guide a standard plunge router to produce straight and uniform sized dovetail joints into the wood.




PERFECT FIT!

 

The plan for the back half of the case is something like this. The back face of the case will be made from not a single plank as the front and sides but 2 12 x 12 lengths that will for the top and bottom of the rear of the case. Into these will be 6 x 6 recesses that I can mount the rear plate in using screws.


I routed out the recesses into the top and bottom pieces using 15mm bit on a router table.


The end result is better then I was expecting to be honest. Due to the round shape of the router bit I had the square up both ends of the cut using a chisel.


The top and bottom lengths sit in recesses in the top and bottom of the side lengths. These are routed using the same 15mm bit and the slider clamp attachment (im sure this has a more technical name) on the router table.

 

The main feature of this design is the aluminium inlay in the front panel.


I had a bit of a mess around with different styles for the front inlay. Either just having round corners or rounding off the entire end. After a bit it was decided that just rounded corners looked better, was easier and was less likely to go south and wreck the whole project.


First I cut a 186mm length of 50 x 3 aluminium bar and then set about rounding off the corners. I could have just done it by eye but that wouldn't have given me a uniform result on all corners, so ( I saw this on some case modding forum and always wanted to try it) a 10cent coin provided the perfect template for the radius of the corner. I just clamped one on each side then filed the metal down around it.



Once I finished all four corners I debured it and cleaned up the heavy scratches with some 240 wet and dry. I will properly polish it up before the end.



The next step is to trace out the outline of the aluminium plate onto the wood. then route out a recess for it to fit into.


The longest edges of the recess were routed first using a guide plate on the base of the router.


The rest of the recess was then removed using the router freehand.


The routing actually went really well, I just had to clean up a few little bits with a chisel.


The inlay is masked off with tape then holes for the power LED and volume knob are drilled out.




Larger holes drilled out in the wood so I can get to the back of the front plate for attaching crap.


Finally araldited inplace.

In my experience when working with hard wood that isn’t always straight and level and even when it is to begin with it can shrink and warp over time the best way to get good results is to have at least one stable base that you know is square and everything else can be measured around. Thus I’ve chosen to make the base from 12mm MDF.


The base is cut square on the triton saw bench.


In order to get the greatest contact area for gluing the base to the sides I used the router table to route out a 6x12 edge on the MDF base.



And the end result.



Before knocking it all together I masked off all the join edges to try and reduce the amount of glue smered over the wood surfaces which will affect how it absorbes the stain/finish later on.




And thats how it turned out.

 

thats nice and that amp is really ugly

 

This looks nice,funy thing is that im also building not my amplifier but my speakers in a wood case with aluminium front, i would love to have a router,anyway you doing a great job, i dont know what you got planed but if you going to polish the aluminium you are going to want to go much higher then 240 grit 1200 if you want a nice shiny finish and 1500 to 2500 for a mirror effect ,depending on how much you want to polish it ,the higher you go the easier it is to polish. Im subribing to this one to folow further progres.

Regards.

 

Yeah I understand what you mean about polishing the aluminium, before a masked it up and put it in i evenly sanded it up 240grit. I didn;t really see much point going further at this point as to get a seamless transistion from the wood to aluminium I will need to do some heavy sanding with <400grit so it would ruin any finishing work I did at this early stage. Once I'm happy with the fit I'll sand both the aluminium and wood up to 1200 then give the aluminium a go with a liquid polish.

 

That sounds nice! by the way you can get mirror finish if you like with a 1200 grit, it just takes a bit more polishing,but concidering the small size of the alu that would not be a problem,you will however see smaller scratches with the 1200 grit (but only if you look cloose).

Regards.

 

Yeah you'll still get small scratches with 1200 but the braso or similar polish will clear those up.

 

I used the wrong word,its not really scratches (them you grit away) but the 1200 paper itself is quite coarse for a final paper, but yes you can get a really nice finish just like i wrote with the 1200 paper it just takes more work polishing it.By the way i dont have much experiense with wood, do you sand it in stages like 60,120,320 and so on, or do you just start with the 1200 paper?.

Regards.

 

I have normally just gone 1200 and polish due to the hardware store i normally go to only stocks up to 1200, I may try and hunt out some 1500 when i get to the finishing stage.

I'm still learning with wood but generally <240 is used to shape the wood then 320,400,600,1200 in that order smooths out the surface so its generally feels nicer as well as opening up the wood (im sure there is a technical term for this) so it will absorb the stain/finish more readly later on.

 

When griting my case i just wanted it to get shiny so i could highlight the smaller details by gritíng them with finer paper (they got a mirror finish),you can get that even with 1200 paper but it requiers more polishing work.
I think you should go for mirror finish since there is no other details to highlight (at least not in aluminium).you can try going to a car painter they usually use up to 2500 paper when they restore/repair autopaint,if you dont find the 1500 or up to 2000 paper and feel that you need it send me a pm and i could send you a 1500 and a 2000 paper free of charge, im not rich (far from it ) but i would not mind helping a felow moder out.
Oh thx for the info on how to sand wood.

Have a nice weekend.

 

The plan was a quite fine finish but not quite mirror. Although this is a detail and I can work out as it all comes together, namely how it matches the volume knob i picked up.

Hey hey its awesome to see modders offering to help each other out like that, thanks. I've got an idea of where I can get some, it shouldnt be to much of an issue.

 

Anyway you do it i think it will turn out nice,if you change your mind and cant fint the paper you know where to find me .

Regards.

 

I really like this idea. I've been wanting a T-Amp for a while now, and even though the new ones are less ugly I think I might have to do something similar when I get one.

One thought, though. A mirror finish on aluminum will probably not be very durable, and will be awful to keep clean and shiny. Have you considered a brushed finish? You can probably manage a linear brush like you see on Lian Li cases, but by hand that might be difficult. However, with a drill press and a round brush, you could give it fish scale effect or a circular brushed finish:

 

Where's the ventilation? T-Amps don't generate a lot of heat, but in a wooden box it will build up...

 

Thanks again, we'll see we'll see

I've had a practice on some spare bits of aluminium with up to 1200 and with the small area i'm confident that I can get a smooth even finish by hand, but there is still a bit of experimentation to be had. I've also had a go at clear coating the aluminium to try prevent light scratching and fingerprints.

Most of my design decisions were based on experiences i read about from other sonic T amp projects. Most people haven;t had a lot of issues with heat even in wooden cases. The amp produces very little heat (the standard case doesn't have any ventilation). But again this isn't set in stone, right up until I start the finishing work and I can still add some ventilation if needs be. Even afterwards I can still modify the base or the backplate.

 

Interesting (or otherwise), I'm actually planning a similar looking box (wooden with aluminium face) but scaled up a bit, to fit a full atx htpc and silent water cooling loop.
I'm thinking of using mdf for the whole chassis though, with a wood veneer.

 

It's a good amp for the price, I own a similar amplifier with Tripath chip bought from 41hz.com.

PS: Have you made the output modifications ?