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The end of tubes?
The end of tubes?
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Old 6th June 2018, 12:40 AM   #41
bluerooster is offline bluerooster
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Quote:
Originally Posted by Bigun View Post
I collect valves here and there as the opportunity arrises and have the one shown attached, a tetrode not a triode. As it needs a 100 Amp heater I don't expect to be using it soon.
An old "pole pig" will feed it nicely. Now finding a suitable input choke would be another animal.
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Old 6th June 2018, 02:37 AM   #42
gabdx is offline gabdx  Canada
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It is simple but costly V1505 at 2.5kv its alright. Just cannot find the tube anymore.
Otherwise you will have to resort to // a few tubes for a so so result.
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Old 6th June 2018, 02:38 AM   #43
JMFahey is offline JMFahey  Argentina
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Quote:
Originally Posted by bluerooster View Post
An SS kilowatt amplifier is way complicated, while a kilowatt tube amp is quite simple.
You-must-be-joking

This is a 1000W tube amplifier.

The end of tubes?


It is way larger than it looks in a picture, those are not KT88 or similar but 813, now scale your mental image up by 3X or 4X

The end of tubes?


Dont worry, supply "only" runs at 2500V DC .... just what the Doctor ordered for a homemade:

Click the image to open in full size.
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Old 6th June 2018, 03:51 AM   #44
gabdx is offline gabdx  Canada
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nice parallel push pull.

the 813 is a toy compared to the V1505
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Old 14th June 2018, 04:17 PM   #45
Traian B is offline Traian B  Romania
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http://www.cpii.com/docs/datasheets/78/8974.pdf


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Old 21st July 2018, 10:17 PM   #46
bluerooster is offline bluerooster
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Originally Posted by JMFahey View Post
You-must-be-joking
I didn't say it was smaller, I said it was simpler. My 300 watt is about the size of a small microwave oven, The PS is inside a large microwave oven cabinet.
But way simple, with P to P wiring, and components that even my fat fingers can handle.

2.5kv for 4 813s? I'm feeding one 813 at that, and when I decide to add a tube, I'll feed the pair with about 4kv. But I'll need two more diodes for a bridge.
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Old 21st July 2018, 11:32 PM   #47
Tubelab_com is offline Tubelab_com  United States
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I'm feeding one 813 at that, and when I decide to add a tube, I'll feed the pair with about 4kv.
And they won't like it. Max continuous plate voltage rating is 2250 volts, intermittent ham radio service shows 2500 volts. The most I have heard of on 813's was just under 3KV and that was in an RF amplifier.

4KV in an audio amp would require an "impossible" OPT. You would need a P-P load impedance of 25,000 ohms or more and it would need to be insulated for about 10 KV.......can't get that at Walmart. I'm guessing the guy who built that 1000 watt guitar amp used 4 813's to get his load impedance down to under 10K and then wound the transformer himself.

My 1KW amp will use TV sweep tubes on less than 700 volts. The load impedance will be 1250 ohms for each of the 500 watt channels. Not necessarily a simple design, but a whole lot easier and safer than wiring up old sparky (the electric chair) in the listening room.
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Old 22nd July 2018, 03:46 AM   #48
sony6060 is offline sony6060  United States
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There enough guitar players to guarantee demand for tubes for many years. In fact I believe they keep tube manufacturing alive in the 1980s & 1990s. Tube audio came back around 1990-2000 era.
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Old 22nd July 2018, 04:13 AM   #49
Wavebourn is online now Wavebourn  United States
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The end of tubes?
Still, plenty of Soviet military tubes are available from Eastern Europe. I even bought several boxes in England!
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Old 22nd July 2018, 06:03 AM   #50
H713 is offline H713  United States
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People often say that "X technology will be gone in the next five years". How many times have they said "The desktop PC will be gone in the next five years", yet here we are. The reality is, manufacturers don't stop manufacturing a product if people want it. And just because something is "theoretically better" or more practical does not mean that everyone will want to use that.

At the same time, we have all heard "In five years time we will all be using tablets for everything". Yet tablets really aren't much more prevalent now than they were a few years ago.

And let's be honest, the 9-year-old boy inside all of us desires things that glow in the dark, are moderately dangerous and extremely inefficient.

And that's the reason that 2A3s and enormous Cadillacs are still made. No they don't make sense, but people love them.
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