Chassis

I took the time to finish the chassis wiring on the spud so that I could focus on the top plate. Now comes the tough part.

I managed to get some time to perform the bulk of the chassis work on the new amp.

Just a quick note on the new project. Ten days ago I posted about how much trouble the wood gave me because of warps and twists in my plank of Bloodwood. Well, today I can say that it was well worth the effort.

I know that I said I wasn’t going to do a lot of posting about my new project, but this morning’s session is worthy of a quick note.

I took some time this morning, now that the paint is dry on the top plate, to install the mechanical aspects of the amp. The top plate is now fully populated.

While dealing with my other spring chores, I’ve been working to get the finish applied to the amplifier’s top plate. While not perfect, I believe it is acceptable enough for me to proceed.

I keep referring to the new amplifier as the 6V6 “Curly Maple” Amplifier. But is it really?

The chassis has all its coats of oil finish and things started coming together today.

I managed to steal a little time over Easter to do a some work in the shop. The chassis for the new 6V6 “Curly Maple” Amplifier is coming along nicely.

After some delay I have managed to finish all the metal work for the Marblewood Upgrade Amplifier. Hereafter referred to as the 6V6 Curly Maple Amplifier.

After getting some chores out of the way this weekend, I got an opportunity to do some chassis work. The project is proceeding well.

We got some unseasonably nice weather here today. Clear blue skies and about 72° outside. This meant I got some time in my shop to move projects forward.

I haven’t talked about the new amp in a while so I thought I’d share current progress.

I’ve been pretty busy for the last month. But things are starting to move forward again. I’m still working on the project page for the Source Selector Unit and something new as well.

As it turns out, there is a crew working on painting the exterior of my house today. Since I can’t work on many of my outdoor projects around the house, I thought I’d take the opportunity to get a little done on the source selector unit.

I got some time today to finish out the vacuum tube assembly of the source selector unit.

Yesterday I was bottling mead but today I got a chance to wire up the buffers and tie in the coupling capacitors. This completes installation of all the signal chain components. All that’s left on the assembly is the final power supply wiring.

I had the opportunity today to sit down and finish up the wiring on the source selector unit chassis. It has been a productive week for this project. Now that the chassis is in good shape, I’m free to move on to the assembly and wiring of the vacuum tube circuits.

I made some progress today on the Source Selector Unit. The twelve twisted pairs are all soldered to the selector switch and I managed some chassis wiring as well.

This morning after installing the selector switch and all its pigtails in the chassis, I decided to install the base plate. The chassis in now all in a single assembly.

So what does one do when needing to keep twelve signal paths clearly separated and easily identified in a chassis? Actually the answer is remarkably simple.

I’ve been waiting for some wire I needed for twisted pairs and a Fender style fuse holder. I really like these fuse holders. I find them sturdy, good looking, and reliable. I have some cheaper ones but I reserve those for brassboards, quick projects, test equipment, and the like. While I’ve been waiting for my deliveries, I’ve been populating the chassis.

I’ve finally completed the finishing of the bubinga chassis. It has four coats of hand rubbed oil finish. It really makes the wood grain stand out.

Today I got the shop cleaned up and applied the first coat of oil to the bubinga chassis for the Source Selector Unit. (Still looking for naming suggestions, by the way.) The oil really brings out the grain. I think it will look even better than I thought it would.

I took some time this afternoon to get the metal work completed (mostly) for the Source Selector Unit/Preamp. All the drilling is complete and everything is properly fit to the chassis. The only metal work left to do is four holes in the mounting brackets which need to be drilled and tapped. These four screws will hold the top plate in place and make swapping tubes easier.

Well, eleven days since my last post and the cedar fence is done, the garden is in, a toilet has been replaced, and a new batch of black cherry cider is in the fermenter. So I decided it was time to get back to the metal for the source selector unit.

I’ve been working on a whole bunch of different projects this last week. But I managed to carve out a little time to get all the chassis metal for the source selector unit cut to size, fit to the chassis, and marked for drilling.

I often get questions about how I design and construct my projects. One of the things I realized this morning, after receiving such a question, was that I really haven’t addressed my basic metal work and how I size all the aluminum parts I use for my chassis. So I thought I’d give a little insight into how I make these cuts and how I got to where I am today.

I’ve been catching up on all my spring chores and managed to steal a couple of hours in the shop this morning. The Source Selector Unit chassis is now all sanded. I also took the time to cut and fit the aluminum for the top and bottom plates. Now my attention will turn to getting all the holes laid out and drilled on the aluminum.

I actually spent a fair amount of time thinking about how to dress the chassis edges for the Source Selector Unit. But after much deliberation, a couple of scrap tests, and some evolution in thought as it progressed, I believe I’ve found a solution I really like.

A good friend of mine, who’s opinion I value, has made a suggestion concerning the Source Selection Unit chassis. And I’m looking for some input.

The chassis for the Source Selector Unit / Preamp is out of the clamps. I removed the clamps, cleaned up the little bit of glue squeeze out at the joints, and gave it a light sanding. It looks fantastic.

Today, I did a little drilling and then got the chassis into glue up.

Before I perform the chassis glue up, I decided I wanted to get the two pieces of metal for the back drilled. This means I can make the pilot holes for the mounting screws in the inside of the back without having to work with a drill inside the glued up chassis. It’s a little thing but it makes the first assembly go that much smoother.

So I had another productive day working on the Source Selector Unit / Preamp chassis. The chassis has all the major woodworking complete and is ready for glue up.

I got some time today to make grain decisions and cut some basic joinery. It finally feels like I’m making progress.

After a difficult and focused three months or so, I am finally getting back to my normal routines. And that means I’m returning to work on my Source Selector Unit/Preamp project. Thank you to everyone who has had patience with my absence from the website.

I got a chance to do a little work on the amp today. I managed to install the top plate on the spalted alder chassis, install the filter inductors for the power stages, connect the output transformer secondaries to the speaker terminals, and wire in the power transformer primary and indicator light.

In the last few days I’ve managed to get most of the wiring on the 6L6 SE-UL top plate complete. This includes all the preposterously large power supply filter capacitors.

The paint seemed to be good and hard this afternoon. So when I got a little free time, I decided to start assembly.

I’m still waiting for the top plate paint to harden. But that didn’t keep me from getting some wiring done on the chassis today.

I know that I told myself I was going to give the paint on the 6L6 SE-UL top plate a week to harden before I started assembly. But then I thought “Hey there’s other assembly I could perform”. So that’s what I did.

A while back in this post, “6L6 SE-UL Primed for Progress”, I mentioned that I would no longer be painting the exposed bottom plates of projects which won’t be seen. What that statement actually meant was that I would be leaving the aluminum in a bare “as delivered” finish. Or maybe with just a little steel wool polishing. But I’m now modifying that stance slightly.

After many delays I have finally finished the 6L6 SE-UL chassis. The paint is still soft but I should get started mounting parts in a week or so, as soon and the paint hardens appropriately.

I suppose by now everyone is wondering what has happened to the 6L6 SE-UL amp project. Well, so am I. Kind of.

Sorry for the lack of progress on the 6L6 SE-UL. I really wanted to get the chassis finished off this week but several factors have conspired to keep me from working on it.

Remember yesterday when I said “There were a couple of finish blemishes which needed to be corrected. I accomplished that shortly after the above pictures were taken”? It looks like I messed up!

So the black finish has set up and I think it looks far better than the grey. So, again, as long as there’s no uproarious outcry, I’ll be going with the black. I think this finish ties the whole project together much better than the grey would have done.

As promised, after the primer was fully dry I took the power transformer down to my shop and put it together with the grey top on the chassis. Whereas the grey would make for an interesting look, I think I’ll like the black better. So unless there’s an uproarious outcry from the amp builders of the world, that’s the way I’ll be going.

Sorry about the title; I couldn’t resist. I got some time today so I applied the primer to the metal for the 6L6 SE-UL amp. The primer takes 24 hours to fully dry so tomorrow I’ll place it in the amp with an Edcor transformer on top and show everyone what the grey looks like with the spalted alder.