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Tubelab SSE Build Thread

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Finally getting there. I have the case together just needs a finish and drill out the tube holes a little bit. Are the tubes ok like this or do I need to drop or raise them?
 

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Nice pretty wood, Purple Heart? I would raise the tubes as far as possible to keep the hottest stuff as far as possible from the wood to avoid discoloration.

Let's see, Pink Floyd, Tourniquet, King's X, something tells me that you might want to try some KT88's or 6550's in this amp someday. They are larger in diameter with bigger bases. Is it possible to raise the board such that the tops of the octal sockets are flush with the top surface of the wood so that any output tubes can be used? If so you may want to move your OPT's as far back as you can for clearance with fatter tubes.

I saw Tourniquet in concert back in the 1990's and picked up a couple of their CD's. They're still in a box from a move 5 years ago. I copied most of my CD's to my PC and boxed up the disks......maybe that's what all the hard drives are for?
 
George thanks for the reply, Yes Purpleheart. I actually have some new EH KT88's that will be swapped in. I will make the holes a little bigger.



I do not have the board pulled up tight against the wood on the bottom, That will bring it up a 1/2 inch or so.


I do enjoy me some Tourniquet. I have test pressings of their first two albums on vinyl, I bought from their drummer. Also looking forward to seeing Kings X again next month.



I'm in the process of moving and the hard drives are from long gone pcs.
 
I moved the board up, I also moved the iron back to give the KT 88s breathing room. How does it look now George?
 

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The 80-20 rule ...

A consequence of the '80-20 rule' is that 20% of the work takes 80% of the time.

Hence once I had my amplifier up and running on my test bed, which is a plywood chassis with all the other components mounted, then even though I was enjoying great sound, I still had 80% of the hard labour to go to get something presentable.

I am getting closer. The new chassis is based on a solid (1mm) stainless steel tray I found in our recycling bins. The base is a recycled table top, glued and dowelled. I still need to finish the wood, and there is a perforated aluminium base plate to be attached.

This is my third project, and each one is a learning experience. The lesson from this project is that it s difficult to adapt the amplifier to the chassis, which was a bit on the small side. There is not as much clearance from the tubes to the OPTs as I would like, but they can be mounted on their sides if needs be in the future.

I have been buying up chassis punches as I need them in different sizes, and at around £9 each from rapidonline.co.uk, they are an absolute boon. I also have a 10mm punch, and that is really useful for starting off te bigger punches since that one only needs a 6mm hole.

On the positive side, I am very pleased with the general ergonomics of the layout. The signal input is on the left side, with a short route to the pot on the front, which is next to the connections on the board. The power is routed on the right hand side, and all the speaker and OPT connections are at the back. I think I will refine this approach on future projects.

The amp is silent when powered up, so the grounding worked well. The mains is earthed at the IEC socket to the chassis. The ground for the amp is close to the potentiometer.

The ALPS potentiometers I have been using come with a little PCB which makes the wiring a doddle.

A couple of questions:

1) I have used a DPDT switch to switch between the 4ohm ad 8ohm secondaries on the OPTs. I don't recall seeing this being done elsewhere, but I limited myself to just two terminals for the loudspeakers. Is there an reason to not use a switch to select output impedance?

2) If I am to be able to measure and quantify the sound quality, then I guess I will have to bite te bullet and have some sort of oscilloscope. I've seen that there are adapters for PCs that can be had for £50 or so ...
Hantek DSO
... are these any good?
 

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