Hey everyone.
Since it's summer but I love my tubes, I want to build a low power amp (under 100W from the wall).
Criteria:
B+ 300V or so.
Triode connection preferred.
RLa-a 3k or 12k (what I have available)
Right now I'm thinking my 6F12P VA/PI concertina driving 6P43P in triode connection, fixed bias or "automatic" fixed bias using a board from audioamp.eu or Tent. Distortion isn't as important as waste heat in this one since the A/C is running anyway.
Does anymore have the parameters for a 6P43P in triode? Like the mu, gm, rp etc?
I usually run them hot but I'm thinking closer to class B on this one, like an idle around 10-20mA?
I also have 6P18P, 6F3P, 6P15P, 6P1P, but I'm thinking for triode mode, the 6P43P kills all of those options.
What do you think?
FWIW: My monoblocs raise the temperature of this apartment about 2 degrees C per hour until the room temp is over 30C unless I install the 12000 BTU unit along with the 5000 BTU (the apartment is only 380 sq ft!) but that raises the room noise to over 70db! Hence the reason for trying for a low powered design. Trying to build this without spending a cent, too.
Since it's summer but I love my tubes, I want to build a low power amp (under 100W from the wall).
Criteria:
B+ 300V or so.
Triode connection preferred.
RLa-a 3k or 12k (what I have available)
Right now I'm thinking my 6F12P VA/PI concertina driving 6P43P in triode connection, fixed bias or "automatic" fixed bias using a board from audioamp.eu or Tent. Distortion isn't as important as waste heat in this one since the A/C is running anyway.
Does anymore have the parameters for a 6P43P in triode? Like the mu, gm, rp etc?
I usually run them hot but I'm thinking closer to class B on this one, like an idle around 10-20mA?
I also have 6P18P, 6F3P, 6P15P, 6P1P, but I'm thinking for triode mode, the 6P43P kills all of those options.
What do you think?
FWIW: My monoblocs raise the temperature of this apartment about 2 degrees C per hour until the room temp is over 30C unless I install the 12000 BTU unit along with the 5000 BTU (the apartment is only 380 sq ft!) but that raises the room noise to over 70db! Hence the reason for trying for a low powered design. Trying to build this without spending a cent, too.
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Well, since I'm doing similar currently as a test build for my "Spider" PCBs, best material I can find for triode mode 6P43P-E-
Tube Tester Files - EL82, EL84, EL86 Soviet Clones
http://www.tubesoundelectronics.de/bilder/kennlinien/6p43ptwax.jpg
http://tec.org.ru/_bd/17/1764_643-.pdf
https://www.diyaudio.com/forums/attachments/tubes-valves/486782d1433514958-vacuum-tube-spice-models-6p43p-ug2-150-pdf
https://www.diyaudio.com/forums/attachments/tubes-valves/486783d1433514983-vacuum-tube-spice-models-6p43p-ug2-180-pdf
I've attached a scanned Russian datasheet, only two pages total
. Maybe Anatoliy (Wavebourne) can help?
Triode mu looks to be around ~7, gm ~7.5mA/V, plate looks to be ~1K to 1.2K depending on application, at least in lower voltage applications. Higher voltage info seems hard to find. It does look like a very lovely tube, even as a driver really. Low triode mu appears to suggest that input capacitance wont be all that bad...
I plan to run ~310 volts supply, 6N2P concertina/volt amp, and garter bias. I'm pretty conservative with bias usually, so 250 volts A-K, 35mA, ~28 volts G1 (820R garter cathode resistors) and a pair of junkbox "30 watt" 6k:8 (or 3k:4) that I think are surplus guitar amp transformers- they'll do 40hz clean no problem down to somewhere around 20 watts, so I figure they would do for either an 8 or 4 ohm speaker in my project. Most of my speakers are 8 ohms, but I plan to build more 4 ohm setups at some point.
Tube Tester Files - EL82, EL84, EL86 Soviet Clones
http://www.tubesoundelectronics.de/bilder/kennlinien/6p43ptwax.jpg
http://tec.org.ru/_bd/17/1764_643-.pdf
https://www.diyaudio.com/forums/attachments/tubes-valves/486782d1433514958-vacuum-tube-spice-models-6p43p-ug2-150-pdf
https://www.diyaudio.com/forums/attachments/tubes-valves/486783d1433514983-vacuum-tube-spice-models-6p43p-ug2-180-pdf
I've attached a scanned Russian datasheet, only two pages total
. Maybe Anatoliy (Wavebourne) can help?Triode mu looks to be around ~7, gm ~7.5mA/V, plate looks to be ~1K to 1.2K depending on application, at least in lower voltage applications. Higher voltage info seems hard to find. It does look like a very lovely tube, even as a driver really. Low triode mu appears to suggest that input capacitance wont be all that bad...
I plan to run ~310 volts supply, 6N2P concertina/volt amp, and garter bias. I'm pretty conservative with bias usually, so 250 volts A-K, 35mA, ~28 volts G1 (820R garter cathode resistors) and a pair of junkbox "30 watt" 6k:8 (or 3k:4) that I think are surplus guitar amp transformers- they'll do 40hz clean no problem down to somewhere around 20 watts, so I figure they would do for either an 8 or 4 ohm speaker in my project. Most of my speakers are 8 ohms, but I plan to build more 4 ohm setups at some point.
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Thanks for the info.
I'm thinking I'll run 2 VPT12-4170 transformers in series for OPTs. It works well enough on the monoblocs (full power at 30Hz). 3k seems good for 6P43P in triode mode. I'm going to use a bias board so it'll be easy to test the amp at different bias points anyway. Turn one pot, change all four tubes at once, right?
I'll start with 300V (or whatever the power supply makes) at 10mA and go from there... If I can make this amp basically benign as far as heat load, I'm good. The VA/PI has a lot of gain, and the OPTs can stand a bunch of gNFB before they act up, so maybe it won't be that bad?
I'm thinking I'll run 2 VPT12-4170 transformers in series for OPTs. It works well enough on the monoblocs (full power at 30Hz). 3k seems good for 6P43P in triode mode. I'm going to use a bias board so it'll be easy to test the amp at different bias points anyway. Turn one pot, change all four tubes at once, right?
I'll start with 300V (or whatever the power supply makes) at 10mA and go from there... If I can make this amp basically benign as far as heat load, I'm good. The VA/PI has a lot of gain, and the OPTs can stand a bunch of gNFB before they act up, so maybe it won't be that bad?
Yeah, they are thirsty pups, and need a good stranglehold to keep it to a trickle
Maybe a differential driver, negative rail for a CCS, and like 200~250 volt supply with garter bias? It'll eat up a bit of voltage making the negative bias more reasonable, and the garter bias scheme will only cost a couple watts in heat...
Maybe go for a 6P1P AB2 build, with a low idle current and fixed bias? Might be easier but transformers are harder to kludge from toroids in that situation. You'll use less heater power overall, which helps.
Maybe a differential driver, negative rail for a CCS, and like 200~250 volt supply with garter bias? It'll eat up a bit of voltage making the negative bias more reasonable, and the garter bias scheme will only cost a couple watts in heat...
Maybe go for a 6P1P AB2 build, with a low idle current and fixed bias? Might be easier but transformers are harder to kludge from toroids in that situation. You'll use less heater power overall, which helps.
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low heat... I remember 6V6 has fairly low heater current at 450mA for similar plate current to the sweep tubes.
Use an SMPS for the heater will save some heat, one of those transformerless lighting modules which give out 12V could power two tubes in series.
SS rectifier saves a lot of heat too
transformer phase splitter saves heat, or use a SS paraphase
Use an SMPS for the heater will save some heat, one of those transformerless lighting modules which give out 12V could power two tubes in series.
SS rectifier saves a lot of heat too
transformer phase splitter saves heat, or use a SS paraphase
I considered using 6P1P which is 6V6 in a 9 pin bottle with a bastard pinout but for another 3 watts of heater, I can use 6P43P and get twice the power.
A transformer PI is a good idea, but I don't have any. I have small toroid power transformers, but I'm read that they have fairly high capacitance and need to be "driven".
So right now, I'm thinking 6F12P VA/PI driving 6P43P in triode. 3K RLa-a. 280V or so. Biased at 20mA to start and see how it performs biased that cold.
I'll be using SS rectification for sure on the power stage, and a CLC filter.
The heaters will be AC from a 30VA transformer (which co-incidentally just happens to be how much heater power the tubes need, and an SMPS for a DC converter for the 380V I use for the VA/PI. Might use another for bias voltage, might use a transformer. Not sure yet
A transformer PI is a good idea, but I don't have any. I have small toroid power transformers, but I'm read that they have fairly high capacitance and need to be "driven".
So right now, I'm thinking 6F12P VA/PI driving 6P43P in triode. 3K RLa-a. 280V or so. Biased at 20mA to start and see how it performs biased that cold.
I'll be using SS rectification for sure on the power stage, and a CLC filter.
The heaters will be AC from a 30VA transformer (which co-incidentally just happens to be how much heater power the tubes need, and an SMPS for a DC converter for the 380V I use for the VA/PI. Might use another for bias voltage, might use a transformer. Not sure yet
I considered using 6P1P which is 6V6 in a 9 pin bottle with a bastard pinout but for another 3 watts of heater, I can use 6P43P and get twice the power.
A transformer PI is a good idea, but I don't have any. I have small toroid power transformers, but I'm read that they have fairly high capacitance and need to be "driven".
So right now, I'm thinking 6F12P VA/PI driving 6P43P in triode. 3K RLa-a. 280V or so. Biased at 20mA to start and see how it performs biased that cold.
I'll be using SS rectification for sure on the power stage, and a CLC filter.
The heaters will be AC from a 30VA transformer (which co-incidentally just happens to be how much heater power the tubes need, and an SMPS for a DC converter for the 380V I use for the VA/PI. Might use another for bias voltage, might use a transformer. Not sure yet
Sounds like a solid plan. That reminds me I need to get back to that driver board PCB for you. Last time I was messing with it I wasn't very happy with how I placed and routed everything, so I might spend some time with a pencil and paper before going back to it.
Do you have any UL transformers? With such nice triode curves I wonder how the 6p43p-e would handle it.
Ok so I'm finished building and testing it.
I made some tweaks to the design and attached is the new schematic.
It draws 103W from the wall which is close enough to 100W for me.
B+ is 320V, biased at 35mA/tube. For that current, the bias is about -50V
1V in for 2.8V out into a 6R load.
I made some tweaks to the design and attached is the new schematic.
It draws 103W from the wall which is close enough to 100W for me.
B+ is 320V, biased at 35mA/tube. For that current, the bias is about -50V
1V in for 2.8V out into a 6R load.
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WOW! - 103 watts AC draw?
I've got an RCA Victor stereo console with 18 tubes (AM/FM tuner/Preamp and stereo PP power amp with 5AS4A rectifier) that only draws 180 watts idling.
This one has three power transformers, three SMPS, two DC boost converters, 6 heaters, VA/PI. This takes 48W. The power stage plate circuit takes the rest and will use more at full volume. Plus, it's almost 15WPC RMS sine in triode mode, and about 5WPC within class A.
FWIW my monoblocs both idle around 230W each. 6 tubes in there as well, but just the output stage uses 60W of heaters and 140W of plate. The rest is VA/PI, the SMPS and boost converter that drives it, and the driver stage. They put out 110WPC, 22W class a limit. My preamp uses 65W now, and has 8 tubes including line stage, two buffers, a dac, bluetooth, and electronic relay volume and input control. It runs from a 12V SMPS feeding several boost converters.
On the bright side, it only draws 0.3W on standby. It has feather touch power control, too.
FWIW my monoblocs both idle around 230W each. 6 tubes in there as well, but just the output stage uses 60W of heaters and 140W of plate. The rest is VA/PI, the SMPS and boost converter that drives it, and the driver stage. They put out 110WPC, 22W class a limit. My preamp uses 65W now, and has 8 tubes including line stage, two buffers, a dac, bluetooth, and electronic relay volume and input control. It runs from a 12V SMPS feeding several boost converters.
On the bright side, it only draws 0.3W on standby. It has feather touch power control, too.
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Sounds really good actually. It's even still clean when turned out loud enough to drown out the A/C
As for power output, I didn't really test it, but it was still looking good with 5V drive. 5*2.8=14V into 6R. This implies 30W or so but I find that hard to believe. They usually put that kind of power out as pentodes, not triodes LOL Although it also could be my disregard for datasheet maximums... The 3k Ra-a load line goes well into the point of exceeding max Pd
As for power output, I didn't really test it, but it was still looking good with 5V drive. 5*2.8=14V into 6R. This implies 30W or so but I find that hard to believe. They usually put that kind of power out as pentodes, not triodes LOL Although it also could be my disregard for datasheet maximums... The 3k Ra-a load line goes well into the point of exceeding max Pd
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