I am about to build a Luxman clone and just managed to "loose" one of the OP tubes, a 50CA10. As someone had noticed already they are almost impossible to find but I make a try to see if anyone in here has a clue.
I think there are a few laying around in Japan but Japanese is not my language ...
PS I have bought a few from a company in Netherland, but I ended up paying for two tubes and getting one working.
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I think there are a few laying around in Japan but Japanese is not my language ...
PS I have bought a few from a company in Netherland, but I ended up paying for two tubes and getting one working.
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Many years ago things looked like this. Bought a chassis from Hammond and sort of roughly sketched how a cloned KMQ60 could look like.
Transformers bought from Analog-Metric and a custommade mains transformer from German company Röhrentechnik.
Saw a note I made that I got a pair (!!!) of 50CA10s for 50 bucks. Now, they are 160-200 buck a pair from AliExpress. I though I hade 7 of them lying around and maybe one was broken ... I had NINE tubes!!!!!
Whilst putting together my un-orthodox 2-way speakers, I realise I need something heavier that 3W SE-tube amps and so much money have been lying around doing nothing.
Drilled and filed the last hole in the chassis and mounted all chassismounted stuff in place. I have all components in a plastic bag but have to add/replace some, so I will pick up a bag from TubesAndMore when I go to Chicago next month.
I have been a bit confused when watching various but similar schematics but right now I go for something that looks like an "original KMQ-60 schematic".
After 13-14 years I am finally on the way ...
Transformers bought from Analog-Metric and a custommade mains transformer from German company Röhrentechnik.
Saw a note I made that I got a pair (!!!) of 50CA10s for 50 bucks. Now, they are 160-200 buck a pair from AliExpress
. I though I hade 7 of them lying around and maybe one was broken ... I had NINE tubes!!!!!Whilst putting together my un-orthodox 2-way speakers, I realise I need something heavier that 3W SE-tube amps and so much money have been lying around doing nothing.
Drilled and filed the last hole in the chassis and mounted all chassismounted stuff in place. I have all components in a plastic bag but have to add/replace some, so I will pick up a bag from TubesAndMore when I go to Chicago next month.
I have been a bit confused when watching various but similar schematics but right now I go for something that looks like an "original KMQ-60 schematic".
After 13-14 years I am finally on the way ...
Attachments
Comparing the triode curves for GEC KT88 and 50CA10 reveals that they are quite close
https://frank.pocnet.net/sheets/084/k/KT88_GEC.pdf
https://frank.pocnet.net/sheets/084/5/50C-A10.pdf
But you will have a problem with the physical layout as the tubes are too close.
https://frank.pocnet.net/sheets/084/k/KT88_GEC.pdf
https://frank.pocnet.net/sheets/084/5/50C-A10.pdf
But you will have a problem with the physical layout as the tubes are too close.
You could :
make a small sheet where 2 kt88 and maybe some preamp is mounted. The
only req is that the sheet will fit between the transformers.
Then cut open the chassies by whatever violent method you want, then
mount the sheet on top of the hole .
Finally sell your working 50ca10 on ebay and buy some nive whiskey for
the money.
When all is built come home to me and we will measure the result for distortion & power.
I vote to finish it like you started it - changing things now will just waste time, and it looks great in its present form. I wouldn't worry about the distance between the tubes here either, provided the amp is used on an open shelf and not in an enclosure. And really, how many people have an amp using these tubes? Think about moving to KT88 if the current tubes prove to be unreliable. I suspect you'll get years out of them, though.
Makes sense to me, I may have got it wrong. I thought it was more of a too close for optimal cooling type thing.
a) Peter proposed that I mount the tubes on separate pieces of metal and at a sufficent distance from each other and then enlarge the holes previous made in the chassis so my new "sub-chassis" will fit.
That's a good idea that solves my problem. However if I don't try hard to make things look good ... it won't look good.
b) I am not using KT88, but the original 50CA10. I have at least 8 working tubes. And the issue is the cooling thing, I guess.
One idea I had was to drill through the holes in the "collars" (the aluminium cover plates) to maybe get some ventilation that maybe was enough.
That's a good idea that solves my problem. However if I don't try hard to make things look good ... it won't look good.
b) I am not using KT88, but the original 50CA10. I have at least 8 working tubes. And the issue is the cooling thing, I guess.
One idea I had was to drill through the holes in the "collars" (the aluminium cover plates) to maybe get some ventilation that maybe was enough.
Problem solved!
I just ordered a new chassis.
The chassis is the 16" x 8" x 2" Hammond alu chassis and the 2" isn't enough.
I am rearranging stuff a little (in Illustrator) and notice that I used the top view of the original as a model and the perspectivs messed things up. Now I am using the underside view as the raw model and alos makes measurements to assure that there's enuff space.
I just ordered a new chassis
.The chassis is the 16" x 8" x 2" Hammond alu chassis and the 2" isn't enough.
I am rearranging stuff a little (in Illustrator) and notice that I used the top view of the original as a model and the perspectivs messed things up. Now I am using the underside view as the raw model and alos makes measurements to assure that there's enuff space.
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