I got a lm3886 kit from chipamp.com
Ive been looking for a simple way to make a tube buffer from it when i came across the lampizator cathode follower using the 6N6P.
Now he uses 2 circuits
links at bottom)
CD DAC MAXI-Lampucera lampizator
In the hand drawn one:
grid R = 200k
cathode R = 330
then an output cap with no resistor to ground after it
In the hard to use office format:
It has an series input resistor of 1 ohm ??? going strait to grid
cathode R = 330
Then an output cap with a resistor(47k) to ground
Im assuming the hand drawn one is correct. Im also assuming (ms format) the input resistor is really the dac load output, and the resistor after the cap is a volume control pot.
Now heres were i have a problem, the heater and B+. My main transformer for the amp is a 22v + 22v (gonna be a 4ohm load). If i used the secondaries as a voltage source, what would be the best way to get 6.3vac(750ma) and 135-150vdc (i cant read his hand writing for current requirements, it looks like 011A or 019A for 2 tubes?
Since the B+ current requirements are so small i was thinking of tapping the rails for 44 and using a small 120/240 euro converter transformer.
Or should i just get a 6.3vac transformer and a 120/120 isolation transformer for the B+? I assume i cant get the B+ strait from the wall...
Ive been looking for a simple way to make a tube buffer from it when i came across the lampizator cathode follower using the 6N6P.
Now he uses 2 circuits
links at bottom)CD DAC MAXI-Lampucera lampizator
In the hand drawn one:
grid R = 200k
cathode R = 330
then an output cap with no resistor to ground after it
In the hard to use office format:
It has an series input resistor of 1 ohm ??? going strait to grid
cathode R = 330
Then an output cap with a resistor(47k) to ground
Im assuming the hand drawn one is correct. Im also assuming (ms format) the input resistor is really the dac load output, and the resistor after the cap is a volume control pot.
Now heres were i have a problem, the heater and B+. My main transformer for the amp is a 22v + 22v (gonna be a 4ohm load). If i used the secondaries as a voltage source, what would be the best way to get 6.3vac(750ma) and 135-150vdc (i cant read his hand writing for current requirements, it looks like 011A or 019A for 2 tubes?
Since the B+ current requirements are so small i was thinking of tapping the rails for 44 and using a small 120/240 euro converter transformer.
Or should i just get a 6.3vac transformer and a 120/120 isolation transformer for the B+? I assume i cant get the B+ strait from the wall...
Your assumption is right, DON'T EVER take any voltage "straight from the wall". This would be very deadly. Always use a transformer with two isolated windings (not a autotransformer) and a fuse.
Concerning your questions:
Not that I encourage you to do so, but you could wind a couple of turns of isolated wire onto the transformer's core (assuming it's a toroid) to get a 6.3V secondary. I'm only mentioning this because you may find this advice somewhere else and might even find some projects where people actually do that, but I strongly advise you not to!
Simply use a higher-voltage primary a regulator, 7806 or better LM317, and use DC for heating. The regulators can drop 20-30V and usually require a heatsink.
You should be able to determine the total current draw from the maximum dissipation of the tubes by looking at their datasheets.
To get the HT B+ from a LT supply can be done with a switchmode PSU, but these are usually noisy, complicated and less reliable. Use a designated transformer for the HT and heater, and make a nice star-ground.
Or even better, use a LT design for the tube buffer, like these:
Tube-buffered Gainclone
Building a valve-buffered Gainclone chip amp.
Tube Gainclone for DIY Buffs
Tubes & The Gainclones
http://www.diyaudio.com/forums/tubes-valves/69625-valve-buffer-gainclone.html
Hope this helps.
Concerning your questions:
Not that I encourage you to do so, but you could wind a couple of turns of isolated wire onto the transformer's core (assuming it's a toroid) to get a 6.3V secondary. I'm only mentioning this because you may find this advice somewhere else and might even find some projects where people actually do that, but I strongly advise you not to!
Simply use a higher-voltage primary a regulator, 7806 or better LM317, and use DC for heating. The regulators can drop 20-30V and usually require a heatsink.
You should be able to determine the total current draw from the maximum dissipation of the tubes by looking at their datasheets.
To get the HT B+ from a LT supply can be done with a switchmode PSU, but these are usually noisy, complicated and less reliable. Use a designated transformer for the HT and heater, and make a nice star-ground.
Or even better, use a LT design for the tube buffer, like these:
Tube-buffered Gainclone
Building a valve-buffered Gainclone chip amp.
Tube Gainclone for DIY Buffs
Tubes & The Gainclones
http://www.diyaudio.com/forums/tubes-valves/69625-valve-buffer-gainclone.html
Hope this helps.
Severe Typo
Wow, I completely messed up this sentence. What I want to say is that you could use a (higher than required) 22V secondary(!) to get a regulated 6.3VDC.
Wow, I completely messed up this sentence. What I want to say is that you could use a (higher than required) 22V secondary(!) to get a regulated 6.3VDC.Hmm. All these are completely different from the chipamp's non inverted setup. However i do like the idea of using a low voltage 6dj8/6922. I will have a bit cooler rails at 30vdc since im shooting for 4ohms. I dont know how to do the math to make a standard cathode follower using this tube.
Back to the lampi version with the 6N6P. I was going to use 2 of these:
http://www.mouser.com/catalog/specsheets/XC-600060.pdf
So i convert the wall to 6.3vac for the heater, then i connect the 2nd one backwards and convert the 6.3vac back to wall voltage. This should give me both voltages i need for about 12 bucks. Ive seen this done in several flea layouts.
Back to the lampi version with the 6N6P. I was going to use 2 of these:
http://www.mouser.com/catalog/specsheets/XC-600060.pdf
So i convert the wall to 6.3vac for the heater, then i connect the 2nd one backwards and convert the 6.3vac back to wall voltage. This should give me both voltages i need for about 12 bucks. Ive seen this done in several flea layouts.
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So this uses 2 E188cc for stereo, 24vdc rails, and 12v heaters?
Hmm. If i went with this, could i use the 30vdc rails for B+? And with the 12v heaters i could just pop in a 12v regulator from the rails too, no extra transformers necessary.
EDIT: Holly crap these are $100 a pair or more...
Hmm. If i went with this, could i use the 30vdc rails for B+? And with the 12v heaters i could just pop in a 12v regulator from the rails too, no extra transformers necessary.
EDIT: Holly crap these are $100 a pair or more...
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Here are two examples of not-so-standard PSUs:
DIY 12AU7 Tube Preamplifier Project with back2back transformers, and
12AX7 Tube (valve) Preamplifier Kit with a DIY SMPS.
DIY 12AU7 Tube Preamplifier Project with back2back transformers, and
12AX7 Tube (valve) Preamplifier Kit with a DIY SMPS.
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