Yes, sure, this is more or less the quintessential com.diff. structure. I would use the laterals at the output driving the speaker with the drains though. You will observe better stability with a speaker load. Lazy Cat mentioned that in his thread at the beginning when his amp was still simple. I mentioned that several times too but it went unrecognized.
What i really need is a little 25W class A amp so we could open a thread " Simple Class A amp with laterals in common source configuration ". What do you think.
What i really need is a little 25W class A amp so we could open a thread " Simple Class A amp with laterals in common source configuration ". What do you think.
I think that the simple lazy-cat is already there...
I have made PCB's for a scaled version..with Transistor current dumping ala Adyton for the output...plan on running it at 56 V rails, Get 10 PCB's this coming week.....could be possible to tweak the PCB a bit.. and cut off the current dumping part..Then your 30 W is there...
but driving from the drain is surely interesting..
I have made PCB's for a scaled version..with Transistor current dumping ala Adyton for the output...plan on running it at 56 V rails, Get 10 PCB's this coming week.....could be possible to tweak the PCB a bit.. and cut off the current dumping part..Then your 30 W is there...
but driving from the drain is surely interesting..
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Fine, you are a busy man. That could be something for me. Could you post the circuit diagram again here ? That other thread got me confused.
Tonight i put the PEN circuit in my system. The only thing i can say is that it plays music and it is low noise. I can listen only quiet at this time in the night and after a lot of component swapping i have some trouble on one channel of my resident MM phono stage.
I will sort it out tomorrow.
I will sort it out tomorrow.
Hi Joachim.. Been fiddling around with the drain tapped poweramp...an can't seem to get i working properly...well it seems like all working points are looking nice.. current in the output fully adjustable..running a nice current (5mA) in the input cascode....But performance is really bad with 2.5% distortion even at low swings...
Will have to look more into this.. Why do you want to take the signal off the Drain..??
I mean the speaker return currents has other ways into the amplifier than though the internal mosfet-diodes...here it runs right into the feedback network..
Will have to look more into this.. Why do you want to take the signal off the Drain..??
I mean the speaker return currents has other ways into the amplifier than though the internal mosfet-diodes...here it runs right into the feedback network..
Maybe this idea to go out the drains does not work with Lazy Cats input stage. I would prefer that connection because of simplicity. Also a lateral Fet is a very good constant current source. I am concerned about the stability of the amp into a complex load. I see here many amps that have THD of less then 0.001% simulated or measured on a dummy load so this problem is solved. For example the TMC blameless that was published in Linear Audio 1. It uses only a few parts and is cheep to make. So why should we design another amplifier ? Self is the champion on low TDH versus cost already. Connected to a real speaker things are not so rosy any more. Anyway Michael, go ahead and design something that works for you. I am curious to investigate it.
The PEN circuit is now working in Stereo. I had an offset problem on one channel of my MM stage. It was caused by a small uninsulated copper wire that was conecting Pin 4 to Pin 3 of my JG-Self MM. The PEN is quiet. I will do more listening today.
I personally think that a mosfet amplifier driving some sets of Bipolar current dumpers is a good way to deal with complex loads,, let en bjt's do the crude current work and then let the fine lateral mosfet amplifier deal with the finer voltage adjustments..this way I believe we can get the best of both worlds...
This is where a am right now....I have made a PCB..And will start to assemble when I have the last components here....It's basically an elaboration on Nico's take on Lazycats circuit...Show's some promise I think..
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Looks good to me. Nice transistors choosen. That in class a could be what i am searching for.
In the meantime i have being working on the PEN circuit a bit more. It sounds very good so i can recommend it as a quick fix. What came to my mind is an AIOG RIAA based on that but with a floating cascode input. i will draw something up and try it.
In the meantime i have being working on the PEN circuit a bit more. It sounds very good so i can recommend it as a quick fix. What came to my mind is an AIOG RIAA based on that but with a floating cascode input. i will draw something up and try it.
and very very good in distortion specter....The pcb I have made is without the bias network...as I have a feeling that a pure resistor-bias is enough to keep it thermally stable...as the negative temp-co of the laterals has a higher slope than the output btj's..If not Ill have to hard-wire it...
You will find out, sure.
Here is my AIOG PEN circuit. It looks a bit exotic even for me but it should work. The input stage is now my well known buffer, inverted and without the trimming resistors. I named the circuit Starless and Bible Black due to an article that Malkolm Hawksford wrote and is also a name of a Robert Fripp album.
The precision mirror has excellent DC stability so i hope i can use it without servo. The circuit is fully floating and needs a supply with one polarity only. If it works i plan to make a PCB this time.
Here is my AIOG PEN circuit. It looks a bit exotic even for me but it should work. The input stage is now my well known buffer, inverted and without the trimming resistors. I named the circuit Starless and Bible Black due to an article that Malkolm Hawksford wrote and is also a name of a Robert Fripp album.
The precision mirror has excellent DC stability so i hope i can use it without servo. The circuit is fully floating and needs a supply with one polarity only. If it works i plan to make a PCB this time.
interesting with the GND reference... good way to get DC-coupling......looks like an interesting concept..temp-co could give some DC float
It could be made all SMD..with the BF parts. small and compact..
It could be made all SMD..with the BF parts. small and compact..
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Hi Joachim
Clever circuit. 🙂
The mirrors can of course be improved a bit, I know that you can make them better.
Cheers
Stein