I like the look of the 813..
The thing that keeps putting me off the big single ended is the heat dissipation into the room...
Thanks for the links..very interesting..
I tried EL34 with G1 input and all other grids to anode via a 1K and it sounded very interesting..(in the past)..however it doesn't lend itself to easy switching for tube change over to U/L etc or tube rolling.
Regards
M. Gregg
The thing that keeps putting me off the big single ended is the heat dissipation into the room...
Thanks for the links..very interesting..
I tried EL34 with G1 input and all other grids to anode via a 1K and it sounded very interesting..(in the past)..however it doesn't lend itself to easy switching for tube change over to U/L etc or tube rolling.
Regards
M. Gregg
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Sorry to have written so much. Did all this work and never saw a return. Others might see a use for it.
EL34 is a champion valve.
I agree about CLC Pi filter PSU. I design chokes for a living so understand the hows and whys. They cost a lot of money if done correctly. The industrial ones I design use M6 alloy as I found it ideal. I get a very wide bandwidth and I don't have just RF to deal with. Chokes in PSU's sometimes do weird things like ringing. Kitic likes valve rectifiers. Ironically they have high output resistance and may be mimicked by adding resistors to soft recovery diodes. My brother thought that best. That brings me to a point . Pi filter, shunt or series regulators all use the last capacitor to do the correct thing although not for identical reasons. The long life if using valve rectifiers is true. The price of EL 34 is not so high as to make me bother. Difference if switched on daily for two hours is about 1.5 to 1 ( ITT TV data) . If running all day there is no difference. The rectifier will cost more and often goes first.
http://www.r-type.org/exhib/aaj0004.htm . The work Kitic has done on 813 would translate. PX 25 is wonderful as is 2A3.
This valve looks the one to think about. It is double which could be very interesting and is indirectly heated.
http://www.tube-and-valve-electronics.co.uk/product_information/6AS7_Electron_Tube.asp
http://www.diyaudio.com/forums/tubes-valves/50764-6as7-amp-schematics.html#post565900
EL34 is a champion valve.
I agree about CLC Pi filter PSU. I design chokes for a living so understand the hows and whys. They cost a lot of money if done correctly. The industrial ones I design use M6 alloy as I found it ideal. I get a very wide bandwidth and I don't have just RF to deal with. Chokes in PSU's sometimes do weird things like ringing. Kitic likes valve rectifiers. Ironically they have high output resistance and may be mimicked by adding resistors to soft recovery diodes. My brother thought that best. That brings me to a point . Pi filter, shunt or series regulators all use the last capacitor to do the correct thing although not for identical reasons. The long life if using valve rectifiers is true. The price of EL 34 is not so high as to make me bother. Difference if switched on daily for two hours is about 1.5 to 1 ( ITT TV data) . If running all day there is no difference. The rectifier will cost more and often goes first.
http://www.r-type.org/exhib/aaj0004.htm . The work Kitic has done on 813 would translate. PX 25 is wonderful as is 2A3.
This valve looks the one to think about. It is double which could be very interesting and is indirectly heated.
http://www.tube-and-valve-electronics.co.uk/product_information/6AS7_Electron_Tube.asp
http://www.diyaudio.com/forums/tubes-valves/50764-6as7-amp-schematics.html#post565900
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Simple 7 Watt pr/ch Ultra linear SE "office amp" with shunt feedback
This is an idea. I don't think the EF184 needs to be run this hard. Very simple mod to RH EL 34 . Set 47K to EF184 g2 to get distortion required.
This is an idea. I don't think the EF184 needs to be run this hard. Very simple mod to RH EL 34 . Set 47K to EF184 g2 to get distortion required.
Hi Banet. The pentode driver I made will give 77V rms unloaded. Here is almost how a 813 amp could be made. I only did this to fake a situation to mimic a 211. 56 Vrms required. I would use a EL34 to be that pentode as we might use up to 800V. You could even have a UL transformer with gain as EL 34 load. I think it gives many possibilities. It gets ride of the coupling capacitor and maybe the grid stopper. M6 metal is cheap enough and might give 100 kHz.
The unexpected outcome was a SE amp quality from an old Maplin 43% UL transformer (OEP 3 kM from where I live). Very cheap and not bad. There is potential for a very high output power and not the dark sound of other PP amps.
Mostly when feedback is applied it looks even more SE. That is a rare and wonderful thing. A small resistor could be added if wanting a lower damping factor (2R ?) if the feedback version.
I often wondered if Alex Kitic tried GU 50 pentode? Looks ideal. I noticed he argued forever to get his point across. I don't think people understood he had found a universal form of amplifier that was so easy to adapt. Not sure Alex realized what he truly did. All other people could do is change it back to what Alex didn't want. It took me half and hour to prove it is a V to I converter. I hate them in some transistor applications (TID in VAS) so was intrigued. No one ever seemed to get that point. OK I did exactly what Alex didn't want. For me it was a choice rather than doctrine.
These drawings are just my notes so may need work to get a good result. Hum was OK but needed a RC section. The mountain to the left of the fundamental is hum. Remember a PP has some advantages with hum.
Conjecture. SE amps sound good because the DC magnetizes the core. This changes the BH curve and effectively makes the transformer more linear if accepting efficiency and LF distortion trade off. Danbury maintains well to 20Hz.
Thanks for the 813 data. I wish my brother could read this. I sent him an e-mail to his old address valvedabbler . Dabbler means someone who plays. If he played then so did Einstein. He was autistic, a very good house builder, plumber, carpenter. He worked as school technician and assistant to the caretaker. He also was the headmasters secretary as unlike me he was not dyslexic.
215K is because I had a big box from MRS25 series for RIAA and other EQ's . 220K is fine. 3V = 8W (3 V range) is as using 10 to 1 probe. I got easily 11 watts. I suspect 20 watts UL if set up for power.
The unexpected outcome was a SE amp quality from an old Maplin 43% UL transformer (OEP 3 kM from where I live). Very cheap and not bad. There is potential for a very high output power and not the dark sound of other PP amps.
Mostly when feedback is applied it looks even more SE. That is a rare and wonderful thing. A small resistor could be added if wanting a lower damping factor (2R ?) if the feedback version.
I often wondered if Alex Kitic tried GU 50 pentode? Looks ideal. I noticed he argued forever to get his point across. I don't think people understood he had found a universal form of amplifier that was so easy to adapt. Not sure Alex realized what he truly did. All other people could do is change it back to what Alex didn't want. It took me half and hour to prove it is a V to I converter. I hate them in some transistor applications (TID in VAS) so was intrigued. No one ever seemed to get that point. OK I did exactly what Alex didn't want. For me it was a choice rather than doctrine.
These drawings are just my notes so may need work to get a good result. Hum was OK but needed a RC section. The mountain to the left of the fundamental is hum. Remember a PP has some advantages with hum.
Conjecture. SE amps sound good because the DC magnetizes the core. This changes the BH curve and effectively makes the transformer more linear if accepting efficiency and LF distortion trade off. Danbury maintains well to 20Hz.
Thanks for the 813 data. I wish my brother could read this. I sent him an e-mail to his old address valvedabbler . Dabbler means someone who plays. If he played then so did Einstein. He was autistic, a very good house builder, plumber, carpenter. He worked as school technician and assistant to the caretaker. He also was the headmasters secretary as unlike me he was not dyslexic.
215K is because I had a big box from MRS25 series for RIAA and other EQ's . 220K is fine. 3V = 8W (3 V range) is as using 10 to 1 probe. I got easily 11 watts. I suspect 20 watts UL if set up for power.
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Nigel
Thanks for your answer !
I just noticed that this thread is dedicated less or more to SE amps , and I must admit that I never liked to much sonic performance of any standard SE tube amps .
Any way if one day I wish to start to build some tube SE amp I will concentrate on pure grounded grid SET amp topology, where output power tube cathode is driven with some fairly linear MosFet .
Your self inverting PP Amp schematic look very interesting , but I must admit that I never tried that configuration .
GU50 is OK tube , very rugged and very cheap , intended for RF OPS in small military transmitters , friend of mine made some RF audio modulator using four GU50 in PP with 1KV on B+ , that modulator work like charm for years .
I use GU50 in RF driver stage to drive two output 813 power tubes working in class C with B+ up to 3KV .
All the Best and salute your brother from me !
Thanks for your answer !
I just noticed that this thread is dedicated less or more to SE amps , and I must admit that I never liked to much sonic performance of any standard SE tube amps .
Any way if one day I wish to start to build some tube SE amp I will concentrate on pure grounded grid SET amp topology, where output power tube cathode is driven with some fairly linear MosFet .
Your self inverting PP Amp schematic look very interesting , but I must admit that I never tried that configuration .
GU50 is OK tube , very rugged and very cheap , intended for RF OPS in small military transmitters , friend of mine made some RF audio modulator using four GU50 in PP with 1KV on B+ , that modulator work like charm for years .
I use GU50 in RF driver stage to drive two output 813 power tubes working in class C with B+ up to 3KV .
All the Best and salute your brother from me !
SE and PP can all learn from the other. Do you know Mt Kitic , I think he is a countryman? Hope Mr Gregg is happy with the answers? It is like a buffet meal.
The monster amp I show could have RH first stage. If the input was EL84 at 35 mA and the transformer has gain it might work as it is. To be clear the transformer is doing at least 4 things and is very 1920's+ UL tap. I am trying to get the lowest distortion and most gain without loop feedback. This idea stated with a transistor to PP other side. I realized the heat would be too much and thought why not this idea. I am using the spare valve to reduce DC imbalance with power byproduct.
Thanks Banat.
The monster amp I show could have RH first stage. If the input was EL84 at 35 mA and the transformer has gain it might work as it is. To be clear the transformer is doing at least 4 things and is very 1920's+ UL tap. I am trying to get the lowest distortion and most gain without loop feedback. This idea stated with a transistor to PP other side. I realized the heat would be too much and thought why not this idea. I am using the spare valve to reduce DC imbalance with power byproduct.
Thanks Banat.
From post 45.
I have fitted the 15 ohm 5 watt mills resistors/ the 22K tantalum input resistors/ and the silmic 2 100uF 63V cathode caps..
The detail has increased it also has Audyn true copper 0.1uF coupling caps. The detail is more noticeable when watching films than with music, sound stage is good.
So there you go....my version of the universal amp. The only trouble is I could just keep changing tubes plug and play...but after now convincing myself to stop before I wear out the tube sockets ......I will have to think of something else to do....the problem is it works with all the different driver tubes as well so you have such a combination to try its better to leave it alone..
Here is the modified amp running some old 6L6G...Also the rotary switch mod..RH High and low feedback and U/L with no RH feedback..
Regards
M. Gregg
I have fitted the 15 ohm 5 watt mills resistors/ the 22K tantalum input resistors/ and the silmic 2 100uF 63V cathode caps..
The detail has increased it also has Audyn true copper 0.1uF coupling caps. The detail is more noticeable when watching films than with music, sound stage is good.
So there you go..
..my version of the universal amp. The only trouble is I could just keep changing tubes plug and play...but after now convincing myself to stop before I wear out the tube sockets ......I will have to think of something else to do....the problem is it works with all the different driver tubes as well so you have such a combination to try its better to leave it alone..Here is the modified amp running some old 6L6G...Also the rotary switch mod..RH High and low feedback and U/L with no RH feedback..
Regards
M. Gregg
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Here are the modified internals..
Its just for interest..
thick film resistors on speaker terminals and True copper coupling caps under the tag boards.
FB resistors are Kiwame all the rest are tantalum. Diode bridge is FRED.
The Heat sinks are the CCS in the tube cathodes that run cool.
Regards
M. Gregg
Its just for interest..
thick film resistors on speaker terminals and True copper coupling caps under the tag boards.
FB resistors are Kiwame all the rest are tantalum. Diode bridge is FRED.
The Heat sinks are the CCS in the tube cathodes that run cool.
Regards
M. Gregg
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RS tag strip. £3 and worth every penny. The RH amp is great because it has so few parts.
GU13. If only
Beam Power Tetrode GU 13 Fu 13 Made in USSR 2 Tubes NOS | eBay
1940's RCA 813 VT 144 Audio Tubes Pair | eBay
GU13. If only
Beam Power Tetrode GU 13 Fu 13 Made in USSR 2 Tubes NOS | eBay
1940's RCA 813 VT 144 Audio Tubes Pair | eBay
Nigel
Be carefull with that`s 813 and GU13 from eBay links !, since they look to me that both pairs are used one , unused 813 or GU13 Must have absolutelly clear glass bulbs , both pairs from eBay is with shadowed glass bulbs on the bottom side near to the tube socket , which is for me sign that this tubes are used and not brand new ( NOS ) .
Be carefull with that`s 813 and GU13 from eBay links !, since they look to me that both pairs are used one , unused 813 or GU13 Must have absolutelly clear glass bulbs , both pairs from eBay is with shadowed glass bulbs on the bottom side near to the tube socket , which is for me sign that this tubes are used and not brand new ( NOS ) .
So there you go..
Inertia. Nice wood, is it old?
I put IC sockets in the transistor stuff I make. Getting people to swap IC's is difficult. Weird as it is easier and more of a no brain choice.
Recently I built a class A SE op amp headphone amp. It gets so loud even like that. The SE modification allows true class A from even from the LM358. That is a device the designers almost rejected. Crossover distortion a way of life with it. It becomes very nice in class A SE. NE 5532 was the nasty reference device (OK). OPA 2604 the sort of thing I should use. funny thing is I will have to set a recommendation as transistor people don't play.
GU 50 GU50 LS50 Russian Pentode Tubes Lot of 4 Pcs Original Boxed | eBay
Recently I built a class A SE op amp headphone amp. It gets so loud even like that. The SE modification allows true class A from even from the LM358. That is a device the designers almost rejected. Crossover distortion a way of life with it. It becomes very nice in class A SE. NE 5532 was the nasty reference device (OK). OPA 2604 the sort of thing I should use. funny thing is I will have to set a recommendation as transistor people don't play.
GU 50 GU50 LS50 Russian Pentode Tubes Lot of 4 Pcs Original Boxed | eBay
The chassis is hard wood with a shellac finish..
..its an old project.Valve bases were mounted on silicone washers (anti vibration).
Top plate screened with EMI tape. Front is glass drilled for the volume control mounted on a copper plate inside. so the glass is not supporting the control
Regards
M. Gregg
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The chassis is hard wood with a shellac finish..
Regards
M. Gregg
Imagine enjoying it with antique transformers and brass details in a classic interior with a good port at hand. That's the hobby now isn't it?
The transformers would probably need overhauling because of oxidized copper from the 1920s. I own a collection of Ferranti and peers for that reason but found a solid wooden case too bulky. Maybe someday in the next 20 yrs
Latest PSU test..
You have to have a play..
Just thought I would add it..quick scribble. And yes I know about the 600uF and the 100uF... (its meant to be that way).
NB the 47K and 15uF replace the ones on the circuit diagram..(10k&22uF)
The fusing could go in the cathodes..however...
Regards
M. Gregg
You have to have a play..
Just thought I would add it..quick scribble. And yes I know about the 600uF and the 100uF... (its meant to be that way).
NB the 47K and 15uF replace the ones on the circuit diagram..(10k&22uF)
The fusing could go in the cathodes..however...
Regards
M. Gregg
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