I am currently developing a DC coupled single ended amp myself (see http://www.diyaudio.com/forums/tubes-valves/178773-el509-jj-pl519.html ). I am using 2K5 output trannies and I am driving the output tubes on their screen grids. Driving the screen grids leaves the control grids free for perfect BIAS adjustment.
My amp is fully DC coupled; sound path is 2 resistors, 4 valves and an OPT. With no feedback applied the sound is absolutely stunning! This thing is beyond reality!
You can view the schematics of the Amp here: http://109.72.83.33/PL519.png
I haven't drawn out the power supply yet because I am still working on it. I am currently running the Amp with a B+ of 360 volts (SS rectified), however I have ordered a new pair of power trannies which should give me a B+ of 400 volts (5R4 GY rectified).
One very important thing is to sepperate the power supply's. I was running the Amp with one power supply for both channels, however this gave me troubles with the current for the output tubes. Yesterday I have build two sepperate power supply's and this solved my problem.
Total costs for building this Amp (in Holland) is about 700 euro's
My amp is fully DC coupled; sound path is 2 resistors, 4 valves and an OPT. With no feedback applied the sound is absolutely stunning! This thing is beyond reality!
You can view the schematics of the Amp here: http://109.72.83.33/PL519.png
I haven't drawn out the power supply yet because I am still working on it. I am currently running the Amp with a B+ of 360 volts (SS rectified), however I have ordered a new pair of power trannies which should give me a B+ of 400 volts (5R4 GY rectified).
One very important thing is to sepperate the power supply's. I was running the Amp with one power supply for both channels, however this gave me troubles with the current for the output tubes. Yesterday I have build two sepperate power supply's and this solved my problem.
Total costs for building this Amp (in Holland) is about 700 euro's
Hello
Thanks lechuck, nice amplifier.
I think I want to use GM70 , that tube can give min 15W triode connected. Let see how we can get the transformers.
The second tube I was interested GU50..
Your amp nice also , I read some short info on the net. How much power you get from one PL519 tube.
The GM70 has powerful bass even used SE with the great mids and highs.
Thanks for your offer, I do not reject totally! Rather I will look more info about your amp.
These tube was used in TV also if I'm right.
Greetings gabor
Thanks lechuck, nice amplifier.
I think I want to use GM70 , that tube can give min 15W triode connected. Let see how we can get the transformers.
The second tube I was interested GU50..
Your amp nice also , I read some short info on the net. How much power you get from one PL519 tube.
The GM70 has powerful bass even used SE with the great mids and highs.
Thanks for your offer, I do not reject totally! Rather I will look more info about your amp.
These tube was used in TV also if I'm right.
Greetings gabor
Hello quikie22
Did you got any info about the OT transformers?
I wrote a PM on Saturday to nomiconxp, unfortunately He didn't answered yet.😕
Probably He is to busy. He offered he would help with these project.
I think we need some special transformer to these amp.
Until I don't have the OT I don't start to buy the rest of the parts. May be I invest a lot in to the parts and I and up loosing that investment..
I think we can do special order from Edcore but I need to know the details of the OT.🙄
Greetings gabor
Did you got any info about the OT transformers?
I wrote a PM on Saturday to nomiconxp, unfortunately He didn't answered yet.😕
Probably He is to busy. He offered he would help with these project.
I think we need some special transformer to these amp.
Until I don't have the OT I don't start to buy the rest of the parts. May be I invest a lot in to the parts and I and up loosing that investment..
I think we can do special order from Edcore but I need to know the details of the OT.🙄
Greetings gabor
Drive the GM70 triode with Aikido preamp
Hello to all
I would like to have a couple question about my GM70 triode amplifier project.
First question the attached schematic is correct??I would like build similar 3 stage amplifier but I want to run my amp about 920V on the plate 80-85 mA.
Second can I drive the GM70 tube with the Aikido octal preamp?I know someone did it , I found in the You Tube GM70 amplifier driven by Aikido. Unfortunately no schematic available.
It would be easier to purchase the PC board for the driver stage.
If I can use the Aikido PC board how I connect the bias for the power tube?
All help are welcome!
Thank you very much.🙂
Greetings gabor
Hello to all
I would like to have a couple question about my GM70 triode amplifier project.
First question the attached schematic is correct??I would like build similar 3 stage amplifier but I want to run my amp about 920V on the plate 80-85 mA.
Second can I drive the GM70 tube with the Aikido octal preamp?I know someone did it , I found in the You Tube GM70 amplifier driven by Aikido. Unfortunately no schematic available.
It would be easier to purchase the PC board for the driver stage.
If I can use the Aikido PC board how I connect the bias for the power tube?
All help are welcome!
Thank you very much.🙂
Greetings gabor
Attachments
I think we would need a higher gm driver than the Aikido. Probably a Tube-lab SE driver or pentode driver. I am currently trying research some driver circuits. I have the octal aikido and don't think it has enough bite to drive the GM70.
Hello quikie22
I sow on You tube Aikido driven GM70! Sounded great...
Also the attached schematic is similar like the Aikido but the second stage only half triode.🙂
That is a working (I don't know if the best , or can bring out the best performance the GM70 tube) circuit.
If you take a look that second stage only half triode, the Aikido second stage a double triode which is much stronger I think (all do I can be wrong)You wrote you have the Aikido, I don't!
Don't forget many DIY-ers built only two stage GM70.
Look the Andrea Ciuffoli circuit. Even do He use inter stage transformer still two stage GM70. He's transformer 1:1. I upload His schematic.
Also I attache a 2 stage 845 which is very close to the GM70. Someone wrote if I change the heater to 20V I can use the 845 circuit !
I do not need 45W from the GM70. 15-18W it would be more than enough.
Thanks any way about your comment, good to know you also search for driver stage for the GM70, I'm not alone.
Please let me know if you find something! I do my homework to..😱
Do you have any OPT idea??
Greetings
I sow on You tube Aikido driven GM70! Sounded great...
Also the attached schematic is similar like the Aikido but the second stage only half triode.🙂
That is a working (I don't know if the best , or can bring out the best performance the GM70 tube) circuit.
If you take a look that second stage only half triode, the Aikido second stage a double triode which is much stronger I think (all do I can be wrong)You wrote you have the Aikido, I don't!
Don't forget many DIY-ers built only two stage GM70.
Look the Andrea Ciuffoli circuit. Even do He use inter stage transformer still two stage GM70. He's transformer 1:1. I upload His schematic.
Also I attache a 2 stage 845 which is very close to the GM70. Someone wrote if I change the heater to 20V I can use the 845 circuit !
I do not need 45W from the GM70. 15-18W it would be more than enough.
Thanks any way about your comment, good to know you also search for driver stage for the GM70, I'm not alone.
Please let me know if you find something! I do my homework to..😱
Do you have any OPT idea??
Greetings
Attachments
Gaborbela sorry for the delay..
I contacted my friend for the output transformers and he told me that he will like to help you out!! 🙂
He asked me to ask you about the specs you will want! 🙂
Everybody else feel free to ask everything you want!
I contacted my friend for the output transformers and he told me that he will like to help you out!! 🙂
He asked me to ask you about the specs you will want! 🙂
Everybody else feel free to ask everything you want!
Hey guys! do you know a good circuit design sofware???
I want to post my schematic of my GM70 Amplifier!
I want to post my schematic of my GM70 Amplifier!
If its purely for drawing a schematic I would suggest you download a trial version of Cadsoft Eagle, additional parts libraries can be found on their website as well.
It's free and (for drawing schematics) fully functional 🙂
I should have asked at the same time, what power out "Watts" are you getting?
Regards
M. Gregg
Do Watts actually matter? I really don't have a clue, so far I have only been listening to the Amp, not messuring.
I am currently running with only one PL519 per channel. The amp seems to deliver more output power than my PP EL84 with 12W per channel does, however I still need to perform messurements on the Amp to know it's actual performance
Watts are not important,
However it's a good guide how it will drive speakers of different efficiency.
If you have more power than the PP EL84 that's good enough..
Regards
M. Gregg
driver tubes
I tryied the D3A, 12GN7A tubes with exellent performance! they can easily drive the GM70!
I tryied the D3A, 12GN7A tubes with exellent performance! they can easily drive the GM70!
Why mess with magnoval tubes??
I you build an amp with a PL519 if you don't like the result what can you do?
Can you change them with other tubes?? you don't have many options......
I you build an amp with a PL519 if you don't like the result what can you do?
Can you change them with other tubes?? you don't have many options......
First of all they are cheap and easy to get your hand on and they can sound very good, they also work extremely well when using screendrive
The magnoval foot shares the same dimensions as an octal foot. If you don't like the PL519 you can replace it with a KT88, EL34, 6550 etc..
Hello
How I wrote I will build two GM70 mono block and a separate power supply.
I have a question.
Can I use these connector for the high voltage 900VDC?
Military Gold 2-Pin Twist Male Female Connector,2FP | eBay
I don't want to waste my money on useless parts.
These military connector but made in China..
How I wrote I will build two GM70 mono block and a separate power supply.
I have a question.
Can I use these connector for the high voltage 900VDC?
Military Gold 2-Pin Twist Male Female Connector,2FP | eBay
I don't want to waste my money on useless parts.
These military connector but made in China..
Hello nomiconxp
Please contact with me. I purchased some Telefunken D3a tubes to.😉
Thank you very much!
Greetings gabor🙂
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