I have almost all of his schematics and built several of his amps in the late 90's, early 2000's.
I like many of the Jean Marc design, I built several of his amplifier but I only used the Zenotron for a while.
I even ordered PCB from France (J Marc) to the Zenquito but never fully materialized.
I do have the stuffed PCB for the GrandMos (missing some parts).
I like this amplifier, I will modify the existing (I will draw a) layout (actually I working on it right now) to these amp, using 2SK1058 & 2SJ162 from Hitachi. Now days hard to find the metal case MosFets, even if you get some very likely fake, replica of aftermarket. Exicon still sell LATERAL mosfets, I prefer the sound of those over the old Hitachi.
I tested in the Zenotron (Class A amp also).
metanastis I hope is not a problem we comment here or posts our experiences, opinions.
You must like this amp if this already your 3th (amp) built.
Greetings gabor
I am really interested in building only class A amplifiers because I am addicted to hifi sound.. I design my own pcbs using spint layout 6.0 and the previous 3 Lang 20W class A have been asked by my friends. They say that they play really good. My trully love is building tube class A amplifiers( I have built 2 which I use all the time- Audio Note 6550 Kit 1 and Cary SLA70) but the output transformer cost is a real problem. My experience in tube amplifiers is really good after 30 years in repairing Radars of the Hellenic Air Force. Besides this forum is for sharing our experiences.
Thank you.
I just finished drawing the Layout for this amp. I use computer paint via hand to draw the layout. I had the Sprint but I never learnt how to use it.
Now days I really do not want to learn it because no one can stop me to build amplifier.
I saved this amplifier schematics many years ago but I was not sure about it. Now I see you build it I think I may give a try,
I have most of the parts at home for a test, who knows.
My printer out of ink so I did not print out the layout! It should work but if someone willing to double check it before somebody decide to use it.
The layout for DIY home brew PCB s.
I used color coding for the parts
Green = RESISTORS
Blue = Capacitors (both type)
Red = Semiconductors
Grey = Jumpers
Purple = Diodes
Yellow = Trimmer
Any question please ask.
I just finished drawing the Layout for this amp. I use computer paint via hand to draw the layout. I had the Sprint but I never learnt how to use it.
Now days I really do not want to learn it because no one can stop me to build amplifier.
I saved this amplifier schematics many years ago but I was not sure about it. Now I see you build it I think I may give a try,
I have most of the parts at home for a test, who knows.
My printer out of ink so I did not print out the layout! It should work but if someone willing to double check it before somebody decide to use it.
The layout for DIY home brew PCB s.
I used color coding for the parts
Green = RESISTORS
Blue = Capacitors (both type)
Red = Semiconductors
Grey = Jumpers
Purple = Diodes
Yellow = Trimmer
Any question please ask.
Attachments
They look identical!!Can you post the schematic diagram.Can you post more details about Jean Marc circuits. I am interested in a new class A amplifier made in France.
Hi
The layout I just posted is the one from Mr Lang the same one you built! I draw the layout for a 2SK1058 & 2SJ162 MosFets.
This one is similar (I mentioned before) from Jean Marc, but it is not a Class A it is a Class B operational.
I also have the ProFet schematic somewhere (I built that amp many years a go) I am not sure if I can upload it here. Selectronic still sell that amplifier in France.
The layout I just posted is the one from Mr Lang the same one you built! I draw the layout for a 2SK1058 & 2SJ162 MosFets.
This one is similar (I mentioned before) from Jean Marc, but it is not a Class A it is a Class B operational.
I also have the ProFet schematic somewhere (I built that amp many years a go) I am not sure if I can upload it here. Selectronic still sell that amplifier in France.
Attachments
Forget to post.
http://jm.plantefeve.pagesperso-orange.fr/prat.html He used to have a huge gallery but it looks like closed down. Want to build a good Class a amp? Please check out the Fab's amplifier or Mr Nelson P. Alephs and First Watt.
http://jm.plantefeve.pagesperso-orange.fr/prat.html He used to have a huge gallery but it looks like closed down. Want to build a good Class a amp? Please check out the Fab's amplifier or Mr Nelson P. Alephs and First Watt.
I think that you can't use different or alternative mosfets without changing the values of the resistors at the final stage
https://www.diyaudio.com/community/threads/ussa-5-pcb-gb.324459/page-39#post-6961919 Fab's USSA 5 amp. He is a French man but from Canada.
I don't know if that count?
I don't know if that count?
I finished one more Lang Class A amplifier layout for 3 Pairs TO3P type Hitachi / Renesans or Exicon power MosFets.
Mirror imaged already ready to iron transfer.
This was my last draw (I hope)!
Do you like Brithish Class A sound like Sugden? Sugden A21SE?
YouTube has many sound "demo".
Reason I ask because it is a Single ended and Class A type (and I like it), I think it is closer to a good tube sound.
I do love it from the net but in a real life never had the chance to listen one.
Mirror imaged already ready to iron transfer.
This was my last draw (I hope)!
Do you like Brithish Class A sound like Sugden? Sugden A21SE?
YouTube has many sound "demo".
Reason I ask because it is a Single ended and Class A type (and I like it), I think it is closer to a good tube sound.
I do love it from the net but in a real life never had the chance to listen one.
Attachments
This still will have relatively high offset due to DC impedance imbalance in the two input sides, as I mentioned for the circuit that the OP posted.
You guys like DC offset? ;-)
Jan
No, certainly not, I do not like offset but it is easy to deal with that if I build it, just need to ad an extra trimmer pot and replace one side the TWO Pc 4K7 resistors with a lower value.
What we can read from metanastis posts a few mV DC offset that is not high, not at all.
Most of Class A amp I built they have some DC offset. A few mV does not make any difference if is stable.
Again it is possible to deal with it if is higher that 100mV or so.
Many Class A amp has some drift at warm up also, to measure that I have to build it or ask metanastis to measure it in cold and after 1/2 hour warm up.
What we can read from metanastis posts a few mV DC offset that is not high, not at all.
Most of Class A amp I built they have some DC offset. A few mV does not make any difference if is stable.
Again it is possible to deal with it if is higher that 100mV or so.
Many Class A amp has some drift at warm up also, to measure that I have to build it or ask metanastis to measure it in cold and after 1/2 hour warm up.
My measurements on that amplifier were done after 15 minutes warming up. Both quiescent current and offset measurements were steady for about an hour because there was no reason to check it any longer.
Here is the pcbs for one channel ( Amplifier board /capacitor board for the final stage/ +-24VDC adjustable power supply for the input stage / Soft start board / VU meter board),I have made via sprint layout 6.0 and have been manufactured in China. One capacitor board is missing for the negative voltage because I have used all of the rest. Please take a look.
Attachments
You got a nice set of PC boards for this project. 🙂
The only reason I will use my layout because I already has the plastic case power mosfets from Hitachi.
My layout is 100% finished, very soon I will have to etch PCB-s for other projects, a the same time I will do this one to.
Plan to test it with 24-25V DC rail voltage. I have some 20 VAC 650 VA toroidals at home.
3 pair power mosfet 1.5A biased to Class A it is plenty for me. 😎
The only reason I will use my layout because I already has the plastic case power mosfets from Hitachi.
My layout is 100% finished, very soon I will have to etch PCB-s for other projects, a the same time I will do this one to.
Plan to test it with 24-25V DC rail voltage. I have some 20 VAC 650 VA toroidals at home.
3 pair power mosfet 1.5A biased to Class A it is plenty for me. 😎
