Hello people,
In my previous thread I mentioned about my system and I described my amplifier, but it wasn't finished cosmetically. It was an enclosure designed from plywood which was thought to be veneered for later, but with the time I realized it was not worth it, because the enclosure didn't suit me. It was very uncomfortable to change parts inside, it was lacking space for high end bulky stuff and the main issue was with the cooling. As a beginner I didn't know some parts would dissipate heat so greatly.
So I designed to remake an enclosure of open nature and also stylish.
I started the project about a week and a half ago. Today I finished it technically and it sings. There are some more cosmetic problems that I will easily remedy later.
The schematic consists of a battery biased triode strapped D3A into 18mA, 190 Ua, driving the 6P45S (it's 6P42S) for now, capacitor coupled. I will have an interstage tranny soon. The 6P45S is triode strapped, it drives a 2,4k load, biased at 120mA, -60Vg, 325 Ua, dissipating 39W. These russian equivalents of EL519 are very rugged and can go to 45W of dissipation, the plate starts going red at about 50W.
There's a separate filament tranny.
There are separate power supply for the driver and power stage
-power stage - 2x6D22S rectification, cap input bosch mp 7uF , then 10H choke DCR 160 and Rifa PEH169 3300uF
-driver stage - EZ81, cap input KBG-MN 4uF, 15H choke DCR 240, arcotronics polypropylene motor runs, choke 10H DCR 220, arcotronics again.
-The fixed bias is rectified via 1N4007, but will be tubed soon. RCRCRC filter with arcotronics propylenes.
The remaining holes are for sockets I will find some use. Remember that this enclosure is made to be very DIY friendly and this is my personal amp that I won't stop upgrading soon.
The parts for the enclosure cost me no more than 20$. Believe it or not, I paid more for the wiring inside (Neotech OCC).
In my previous thread I mentioned about my system and I described my amplifier, but it wasn't finished cosmetically. It was an enclosure designed from plywood which was thought to be veneered for later, but with the time I realized it was not worth it, because the enclosure didn't suit me. It was very uncomfortable to change parts inside, it was lacking space for high end bulky stuff and the main issue was with the cooling. As a beginner I didn't know some parts would dissipate heat so greatly.
So I designed to remake an enclosure of open nature and also stylish.
I started the project about a week and a half ago. Today I finished it technically and it sings. There are some more cosmetic problems that I will easily remedy later.
The schematic consists of a battery biased triode strapped D3A into 18mA, 190 Ua, driving the 6P45S (it's 6P42S) for now, capacitor coupled. I will have an interstage tranny soon. The 6P45S is triode strapped, it drives a 2,4k load, biased at 120mA, -60Vg, 325 Ua, dissipating 39W. These russian equivalents of EL519 are very rugged and can go to 45W of dissipation, the plate starts going red at about 50W.
There's a separate filament tranny.
There are separate power supply for the driver and power stage
-power stage - 2x6D22S rectification, cap input bosch mp 7uF , then 10H choke DCR 160 and Rifa PEH169 3300uF
-driver stage - EZ81, cap input KBG-MN 4uF, 15H choke DCR 240, arcotronics polypropylene motor runs, choke 10H DCR 220, arcotronics again.
-The fixed bias is rectified via 1N4007, but will be tubed soon. RCRCRC filter with arcotronics propylenes.
The remaining holes are for sockets I will find some use. Remember that this enclosure is made to be very DIY friendly and this is my personal amp that I won't stop upgrading soon.
The parts for the enclosure cost me no more than 20$. Believe it or not, I paid more for the wiring inside (Neotech OCC).
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Interesting construction technique.. 😀 Please get some plate caps for the rectifiers and the EL519 - this is a safety hazard.
That's pretty cool, I like it a lot.
Upgradeable too, great idea.
It's like a finished 3D breadboard.
A few sheets of glass or acrylic might be a good idea.
Upgradeable too, great idea.
It's like a finished 3D breadboard.
A few sheets of glass or acrylic might be a good idea.
I'm glad you like it.
I don't plan putting removable plate caps, because they degrade the sound. I will keep the solder joint and put just a protective cap instead.
I don't plan putting removable plate caps, because they degrade the sound. I will keep the solder joint and put just a protective cap instead.
I had the same thought before trying it personally. The same way as cable directions, fuses, power switches. 😀
Well done 50AE.
I like very much the idea to have separate powersups for driver and powerstage. My amps are allways like this. 6D22S is a great rectifier- one of the best.
Thanks a lot for showing us your work.
Hilmar
I like very much the idea to have separate powersups for driver and powerstage. My amps are allways like this. 6D22S is a great rectifier- one of the best.
Thanks a lot for showing us your work.
Hilmar
Hello 50AE,
nice one 🙂
But be careful with the operating point of the D3a. Ug2 max is only 180V. You´re 10V above it. The datasheets recommends Ua=Ug2=150V.
Best regards,
Martin
nice one 🙂
But be careful with the operating point of the D3a. Ug2 max is only 180V. You´re 10V above it. The datasheets recommends Ua=Ug2=150V.
Best regards,
Martin
They won't affect the signal to the speaker. If loose, they might rattle a bit - just like any other loose object in the room.Shoog said:
However if the OP needs to omit them for good sound, as a sportsman needs to wear his lucky socks, then so be it.
I guess I wasn't careful enough when reading the datasheet. It has been running at 185-190 Va since months. There is a 300R going from the plate to g2.
I can decrease the Ua by shifting the bias point to 1,28V using a Ni-MH for bias. Now I use a 1,5V Duracell.
Everything in this amp is built from decisions by ear. I even don't have an oscilloscope, but I'll buy one for 2014.
In my opinion, the 6P42S / 6P45S are "sleeper" tubes.
This was my system before major upgrades - power cables, interconnects, rectifiers, enclosure:
http://www.youtube.com/watch?v=fKR52V5iTOA
Now it sounds much better 🙂
I can decrease the Ua by shifting the bias point to 1,28V using a Ni-MH for bias. Now I use a 1,5V Duracell.
Everything in this amp is built from decisions by ear. I even don't have an oscilloscope, but I'll buy one for 2014.
In my opinion, the 6P42S / 6P45S are "sleeper" tubes.
This was my system before major upgrades - power cables, interconnects, rectifiers, enclosure:
http://www.youtube.com/watch?v=fKR52V5iTOA
Now it sounds much better 🙂
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wow... very innovative amplifier chassis... watch out for overheating and burning of the wood... 🙂
Hello 50AE,
The 300R isn´t helping much because g2 current is quite low.
I wouldn´t do that. Grid current starts to occure at -1,3V. Even with 1,5V you only can apply 200mVpp until your signal gets distorted. There is not much headroom.
In my opinion, the D3a is not suitable as input tube for a power amplifier. But it´s a great tube for phono amplifiers 🙂
Best regards,
Martin
The 300R isn´t helping much because g2 current is quite low.
I wouldn´t do that. Grid current starts to occure at -1,3V. Even with 1,5V you only can apply 200mVpp until your signal gets distorted. There is not much headroom.
In my opinion, the D3a is not suitable as input tube for a power amplifier. But it´s a great tube for phono amplifiers 🙂
Best regards,
Martin
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How do you know this? It's very important info! How much grid currents it draws until it reaches 0v?
Then, what about E180F, E280F, E810F?
Merry Christmas!
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Hello,
grid current always starts at about -1.3V. It´s often mentioned in the datasheets. That´s why you should avoid to reach this region with your input signal. The operating point of most high transconductance valves is in the region of -1.5V. This allows you to apply only 200mVpp. Perfect for phono amplifiers but not quite for power amplifier input stages with probably more than 1Vpp.
The E55L is the only exception I know. There it´s -3V. I´m using it wired as triode to drive my F2a SE. Input sensitivity is about 1.5Vpp with some negative feedback.
Grid current can easily reach 2µA and more. Measured on a E810F with grounded cathode (phono input stage). The MC transformer was heavily disturbed by the grid current.
I don´t know how much gain you need. Using a D3a I guess a lot 😉 Have you ever thought about using a pentode? The EL84 comes to my mind as noval valve.
Best regards,
Martin
grid current always starts at about -1.3V. It´s often mentioned in the datasheets. That´s why you should avoid to reach this region with your input signal. The operating point of most high transconductance valves is in the region of -1.5V. This allows you to apply only 200mVpp. Perfect for phono amplifiers but not quite for power amplifier input stages with probably more than 1Vpp.
The E55L is the only exception I know. There it´s -3V. I´m using it wired as triode to drive my F2a SE. Input sensitivity is about 1.5Vpp with some negative feedback.
Grid current can easily reach 2µA and more. Measured on a E810F with grounded cathode (phono input stage). The MC transformer was heavily disturbed by the grid current.
I don´t know how much gain you need. Using a D3a I guess a lot 😉 Have you ever thought about using a pentode? The EL84 comes to my mind as noval valve.
Best regards,
Martin
Well, how much are 2µA evil? My source has 80R output impedance and can even go lower to 50R if I wish so? Can't the source combat this grid current?
I was thinking about a 3 ladder stage, using a double triode like 6N6P for example. Direct coupling between both triodes, fixed battery bias for the first triode, auto bias for the second triode.
I was thinking about a 3 ladder stage, using a double triode like 6N6P for example. Direct coupling between both triodes, fixed battery bias for the first triode, auto bias for the second triode.
Here's a video of my system with some songs for demo 🙂
http://www.youtube.com/watch?v=EGD7HiMiVqQ
Recorded with Panasonic DMC-LX7. What you hear is about 10% of the sound and emotion. The camcoder can't capture the lows either.
http://www.youtube.com/watch?v=EGD7HiMiVqQ
Recorded with Panasonic DMC-LX7. What you hear is about 10% of the sound and emotion. The camcoder can't capture the lows either.
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Thanks for sharing.
Despite the camcorders audio, you can still get a little taste of it.
I have the attention span of a fruit fly, so I skip around a bit.
Despite the camcorders audio, you can still get a little taste of it.
I have the attention span of a fruit fly, so I skip around a bit.
Here's a video with a few updates.
https://www.youtube.com/watch?v=a0TwuTkcXJE&feature=youtu.be
First, displacement of the system, as it sounds better now.
Secondly, E810F tube as driver for now.
Thirdly, Mundorf audiophiler last capacitor before the driver tube.
My weakest spots for now are the room acoustics and the DAC, so I'm not in rush for the amplifiers. They sound great.
Regards, 50AE!
https://www.youtube.com/watch?v=a0TwuTkcXJE&feature=youtu.be
First, displacement of the system, as it sounds better now.
Secondly, E810F tube as driver for now.
Thirdly, Mundorf audiophiler last capacitor before the driver tube.
My weakest spots for now are the room acoustics and the DAC, so I'm not in rush for the amplifiers. They sound great.
Regards, 50AE!
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