Hi Guys
Advice pls. Been researching the above tube. Notice that aside from 01A numbering,
I see SX 201A, UX 201A, CX 301A etc. Are they all the same tube type.
Many Thanks
Advice pls. Been researching the above tube. Notice that aside from 01A numbering,
I see SX 201A, UX 201A, CX 301A etc. Are they all the same tube type.
Many Thanks
This should cover most, if not all, of what you need to know about 01a.
VinylSavor: Tube of the Month : The UX201A
VinylSavor: Tube of the Month : The UX201A
The voltage and current requirements of the 01A are very benign. You can use whatever makes you happy.
If looks are important just look around what type of globe rectifiers you can find cheaply (maybe type 80??) and go with that.
If looks are important just look around what type of globe rectifiers you can find cheaply (maybe type 80??) and go with that.
If you're thinking of building Ale Moglia's 01A Gen 2 preamp, then that's the best preamp I've ever heard. If you aren't you should be!
01a Preamp (Gen2) | Bartola Valves
01a Preamp (Gen2) | Bartola Valves
It's transparent, airy, almost as if it isn't there at all. I found it quite magical. Better than a 26 preamp with LL1692 in 2:1. Better than a 4P1L preamp. That's a lot of "better".
But be clear that this is a complex design which needs to be built EXACTLY according to the schematic - absolutely no short cuts. Every component is there for a reason.
But be clear that this is a complex design which needs to be built EXACTLY according to the schematic - absolutely no short cuts. Every component is there for a reason.
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Thanks Andy yes I am going to build that preamp.
I prefer going with tube rectifier instead for HT
supply.
Thanks again
I prefer going with tube rectifier instead for HT
supply.
Thanks again
Tube rectifier is OK. I use AZ1 mesh. Any mesh rectifiers are the best - AZ11 is the same, different base. I thought Ale used a tube rectifier?
Ale brought round his preamp - the one on his blog - and we listened to it in my system. I remember his power supply was shared with his 4P1L preamp but not what was in it. He probably did have a Salas reg, but that would come after the rectifier. Use an AZ1 mesh if you want the best.
Thanks again for the advice Andy. Will hunt around for some AZ1. Btw why does globe version sound better then ST. Any idea Andy ? Actually I like the looks of ST more.
The AZ1 mesh is audibly better than the solid plate version, so technically it's the mesh. No idea why.
I think with globes and ST versions it depends a lot on the state of the tube - some of these are almost 100 years old.
Basically the 01A has a thoriated tungsten filament, like the 801 and 10Y and some other highly valued tubes. I'm sure somebody could say why this makes a difference - not sure myself.
Actually it's a bit more complex. You can tell by applying voltage to the filament. Thoriated Tungsten will be much brighter than coated cathode type. Original 201's were Tungsten. These draw 1 amp and light very bright. Later tubes were marked 201A or 01A and used Thoriated Tungsten. These drew .25 amps and were not as bright but still very noticeable. More recent 01A's used coated cathodes. Some of these can barely be noticed in lighted areas. Believe these tubes should have been marked 01AA but not everyone did this. If you find tubes marked 01AA they have coated cathodes but so do later 01A's.
01 = 1 amp filament
01A = 250 ma filament
01B = 125 ma filament
01C = 60 ma filament
More information and pictures here:
http://vinylsavor.blogspot.co.uk/2013/10/tube-of-month-ux201a.html
I think with globes and ST versions it depends a lot on the state of the tube - some of these are almost 100 years old.
Basically the 01A has a thoriated tungsten filament, like the 801 and 10Y and some other highly valued tubes. I'm sure somebody could say why this makes a difference - not sure myself.
Actually it's a bit more complex. You can tell by applying voltage to the filament. Thoriated Tungsten will be much brighter than coated cathode type. Original 201's were Tungsten. These draw 1 amp and light very bright. Later tubes were marked 201A or 01A and used Thoriated Tungsten. These drew .25 amps and were not as bright but still very noticeable. More recent 01A's used coated cathodes. Some of these can barely be noticed in lighted areas. Believe these tubes should have been marked 01AA but not everyone did this. If you find tubes marked 01AA they have coated cathodes but so do later 01A's.
01 = 1 amp filament
01A = 250 ma filament
01B = 125 ma filament
01C = 60 ma filament
More information and pictures here:
http://vinylsavor.blogspot.co.uk/2013/10/tube-of-month-ux201a.html
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Hi Andy
Thks for the explanation. My own thoughts was that if the difference in volume between ST & Globe had any effect on the tube itself. Perhaps shape of the glass might even affect the sound. Sounds berserk right ?
Thks for the explanation. My own thoughts was that if the difference in volume between ST & Globe had any effect on the tube itself. Perhaps shape of the glass might even affect the sound. Sounds berserk right ?
Don't forget to mention, that 01a is very sensitive to the load.
My breadboarded 201a preamp (SSHV2, 22R filament bias -0.25A Rod Coleman regulator- , cascode CCS load- 5mA-, 0.47uF - 100k load) was able to fall 3dB at 10kHz due to the 5m coax cable (connected to the oscilloscope)!
My breadboarded 201a preamp (SSHV2, 22R filament bias -0.25A Rod Coleman regulator- , cascode CCS load- 5mA-, 0.47uF - 100k load) was able to fall 3dB at 10kHz due to the 5m coax cable (connected to the oscilloscope)!