Generaly the recommended bias for 2SJ162/2SK1058 is 100mA
to 120mA/device as there s nothing substancial that is gained from
increasing the quiescent current.
Moreover , suppressing the source resistor extend the power range
at wich the devices have a square law behaviour so with 3 pairs
and a total current of 300mA this allow to have pure class A up
to a few watts.
If thermal dissipation/power comsumption seems to you too high
you can reduce the supply voltage to half the value since the circuit
has wide power supply variation ability.
The Grand Mos amplifier has not good perfs as lateral fets do not
suit low negative feedback designs , i wouldnt recommend this amplifier
unless one is not troubled by high THD levels at medium power.....
How did you arrive at this conclusion?
300mA output bias will give <600mApk of ClassA output in a push/pull amplifier, i.e. <1.44W of ClassA into 8r0.
Hello Jay
Are you talking about my Darlington amplifier?? I posted about 2 years a go, I'll post the basic circuit here.
If that is what you are talking I have to let you know sound wise I still didn't find a amplifier even come close to that!
These is a humble statement.
Built and tested over 100-120 amplifier (from N Pass, Symasym, Gainclone P Daniel, Hiraga both,so on)!
I owned (prepared or sold) over 450 commercial amplifier, nothing can be mentioned in the same category.
I do rebuild that amplifier soon.
Only think it has a thermal stability problem.
Examp. I set up the bias 100mA, when the heatsink warm up the bias goes higher and it get warmer the bias goes higher until it self destruct herself.
To avoid these problem req. over sized heatsink..Whit that remain stable.
I don't know if I would remove the BD136 from the main heatsink what would happen. I never tested that way..
The amp last time used TIP142/147 power Darlington (one pair)
MJE243/253 driver and 2SK170/2SJ74 input.
I used 4.7uF BG non polar on the input, the power resistors must be 0R22.
Last time I built 1 par darlington, now I'll use 2 par and over sized heatsink.
If the amp get the right size heasink it has no problem with thermal stability.
My friend used these amp over 10 years with 400mA bias but huge with huge heatsink.
He also didn't find better amplifier than these (sound wise)
My upgrade, the mentioned transistors made the amplifier even sound better! Specially the JFet input and reduced 5W resistors from 0R47 TO 0R22.
Also the MJE much better device than the BF469/470 which only produced in India today.
I built several amplifier like the SSA, Megalith,Hiraga le Monstre etc !
Cooltune
I do not want to write anything about since I saw is very popular on the forum!
Why I'm interested these mosfet amplifier? I have all those Hitachi mosfets I did purchased for the GrandMos and other similar amp.
The GrandMos very popular in France (cost over 2000Euros), that is why I have the stuffed PC boards.
But I read the ProFet is better amplifier, same designer but the Profet 25W in Class A .
Guess what I built the Profet with high quality parts Caddock and Takman resistors, Russian PIO capacitor etc.
I tested and tested with different quality parts and the mentioned gave the best performance.
The sound quality remain well behind to my Darlington.
I agree not so easy to build a great sounding amp but if you get a certain level it always possible to try to improve it.
I'll test these amplifier wahab came up!
Greetings Gabor
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Yes, that one. Basically it is an SSA without the input cascode.
Yes, the issue with the topology is bias stability. The absence of input cascode makes it worse. Also the use of darlington output, requires high bias (at least 1A) for medium output. And at least 2 pairs. The 100K feedback resistors in your circuit help a lot.
Have you tried darlington compensation circuit? May be not necessary. I think BD140 will do.
Your darlington amp is similar (apart from input cascode and feedback to VAS) with the SSA, not Megalith, LeMonstre, etc. Remember, it doesn't have to be class-A with SSA. That's a plus especially with latfet.
Why I'm interested these mosfet amplifier? I have all those Hitachi mosfets I did purchased for the GrandMos and other similar amp.
The GrandMos very popular in France (cost over 2000Euros), that is why I have the stuffed PC boards.
But I read the ProFet is better amplifier, same designer but the Profet 25W in Class A .
Guess what I built the Profet with high quality parts Caddock and Takman resistors, Russian PIO capacitor etc.
I tested and tested with different quality parts and the mentioned gave the best performance.
The sound quality remain well behind to my Darlington.
Have you tried F5? Tho F5 is very small in power and selective with the speaker, it is an improvement over the Grand Mos and ProFet, in the driving of the latfet (it is a criteria you will find critical in all NP's mosfet amps).
They are all class-A amps, and with limited power.
With SSA you can make class-B amps. And power can be made bigger without excessive THD increase.
Yes, in other words, we find the best one in one topology, and improve it. That is the way how better amps are found every time.
The SSA and similar CFB topology has not been well known to mass to produce good sound (may be because of the stability issue), so there is still big room for "improvement" (popularization actually).
OTOH, the Hitachi topology has been examined to detail. It is very old topology and has been used many times. You can even add a beta-enhancer for the VAS. An important criteria for this topology is the high voltage rail. Goldmund Mimesis is the best I have seen/tried (as a result of such topology).
BTW, The Momentum amplifier is hot nowadays. Everybody is curious with the schematic. Elvee is also running a VFB versus CFB thread and showing part of his "ultimate" HyperBrq amp with FB applied to VAS (I believe) and input stage using an opamp. Very similar to Marantz high end amp. We all learn from the best to get the best.
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Yes, that one. Basically it is an SSA without the input cascode.
1) Yes, the issue with the topology is bias stability. The absence of input cascode makes it worse. Also the use of darlington output, requires high bias (at least 1A) for medium output. And at least 2 pairs. The 100K feedback resistors in your circuit help a lot.
2)Have you tried darlington compensation circuit? May be not necessary. I think BD140 will do.
3)Your darlington amp is similar (apart from input cascode and feedback to VAS) with the SSA, not Megalith, LeMonstre, etc. Remember, it doesn't have to be class-A with SSA. That's a plus especially with latfet.
4)Have you tried F5? Tho F5 is very small in power and selective with the speaker, it is an improvement over the Grand Mos and ProFet, in the driving of the latfet (it is a criteria you will find critical in all NP's mosfet amps).
They are all class-A amps, and with limited power.
With SSA you can make class-B amps. And power can be made bigger without excessive THD increase.
Yes, in other words, we find the best one in one topology, and improve it. That is the way how better amps are found every time.
The SSA and similar CFB topology has not been well known to mass to produce good sound (may be because of the stability issue), so there is still big room for "improvement" (popularization actually).
OTOH, the Hitachi topology has been examined to detail. It is very old topology and has been used many times. You can even add a beta-enhancer for the VAS. An important criteria for this topology is the high voltage rail. Goldmund Mimesis is the best I have seen/tried (as a result of such topology).
Hello Jay
If we talk about these amp I think we should go to the original thread These Darlington amplifier it deserve to build it (not to give up) even if isn't stable.
I do not want to modify the circuit if that degrade the sound just a bit 5% or so!
Probably I would test it how it is with lateral fet on the end.
I do not think it is hard to drive the darlington devices, originally it was biased 20mA and sounded excellent.
With my friend we tried higher bias, he run his amplifier almost 10 years with one par BDW83C/84C - 400mA/channel!
I did tested 3 pair power transistor 22V rail at 3A bias. Not much improvement.
I got more improvement with the right components the right place.
These amp very-very sensitive to all parts I used.
I burned these amp a couple time, I used to small heatsink. I didn't knew it has these thermal runaway problem.
It took out my woofer one time.
Again the sound I get with these amp do not let me to give it up.
Huge dynamic, crystal clear sound with huge bass nice open mids and great highs.
Now I put together a huge heatsink (it would be enough a 25W PP amplifier biased in Class A all the way)
I'll build it as a mono block to get the maximum performance.
I wish someone from the forum would hear the sound of these amplifier.
One day a guy came to my home (all his life listen music on his expensive system) he could not believe the sound he heard.
When I told I built the amp he look at the amp connection & (follow with his hand from the amp until the speaker) the speaker wire if really that amp drive the speakers. He could not believed even after he realised that is the amp.
Yes I'll test the F5 T1 with 4 pair Toshiba 2SJ200 / 2SK1529 (HIGH POWER)
I plant to build a low power also with Toshiba higher power device.
To understand me I like huge authoritative well controlled bass.
All amp I built from N Pass somehow I missed that type bass.
I do not say they are bad, they are great amp! All do I already sold my Aleph30.
I'll build the A40 which use also darlinton power transistors probably that.
These All Fet amp circuit was special to me but after wahab sim I think I test it with the BJT VAS.. May be better than the GrandMos.
About the GM Minesis clone Sakis wrote the Elliot P3A much better amplifier!
So what can I write now..
I do finish my SS project and I go back to the valve.
I plan to build a GM70 SE amp and a GU50 SE, in if that sound bad I'll rebuild it go with 300B power tube.
I do have the transformers for the second amp.
That will be my last DIY project.
Greetings Gabor
With my friend we tried higher bias, he run his amplifier almost 10 years with one par BDW83C/84C - 400mA/channel!
I did tested 3 pair power transistor 22V rail at 3A bias. Not much improvement.
I got more improvement with the right components the right place. These amp very-very sensitive to all parts I used.
I burned these amp a couple time, I used to small heatsink. I didn't knew it has these thermal runaway problem.
It took out my woofer one time.
I'm not an expert so I feel lucky that I can find good correlation between simulation and reality while many can't.
I wish someone from the forum would hear the sound of these amplifier.
I have heard many SSA variations: darlington, latfet, bjt, hexfet...
Nothing is coincidental. If you want your bass, it is easier if you forget mosfets especially latfet. Go for BJT, preferably triple EF output like the End Millenium etc, and minimal 3 pairs of output.
It takes "hard work" to fine tune mosfet amps for good bass. Even if they have good bass, it is probably still different. But my taste is with the mosfet. And SE amp like Aleph... it doesn't work with most speakers to display good enough bass.
Your darlington amp is good not because of the darlington. NP who designed the A4, has not so favorable opinion about darlingtons... so the sound of packaged darlington is well known (well, my gold plated darlingtons are better than even the Philips used in your CFB amp). Then, where is the quality come from if not from the darlington? Build another similar circuit, then you will know.
Hehehe... It was probably more about taste. Sakis loves DX amp too. In general, Mimesis bass is terrible. And Sakis (and Carlos) seems to love "that" typical bass. I don't like BJT in general, but I like CFP. My BJT devices are only for CFP...
Hello
N Pass amplifiers are great!
You know Mark Finnish built at first the A40 and used over ## years.
After he built the Aleph5 and compared with.
He preferred the A40 he did missed the A40 when he listen his Aleph5.. After he built a Aleph4 thought his speaker need more power but on the end he realised not the speaker.
How you wrote it have to match (pick the right speakers) the system.Some amplifier it is easier to be matched into the system.
I'm not as fanatic to say I do like BJT and nothing else.
I like good sound, does not matter tube, BJT, HEXFET, LFet darlington etc.
To be honest darlington has a bit different sound (warmer, and faster) than BJT, at least to me!
I did listening PP tube amps, SE tube amp, mosfet amp BJT for years!
I would not say any of them just bad.
Do not misunderstand me please, the music to me not just bass. All do I like great bass.
If you ask Sakis any amplifier use Darlington it can't be good that his opinion, I did read that..
About the DX amp I didn't heard one so I can't comment.
But to me those devices Toshiba power transistors (so many of them are fake) or BD139/140 devices aren't my favorite..
I used those BD's in several circuit, when I replace them always I got sound upgrade.
I did used from Philips, ST etc.
The reason I didn't built the DX yet, probably I will never.
So many guy wrote how great the Symasym, so I built it at first test I knew that is not to me, not a keeper. I used all exotic parts spent $$$ on parts.
Well we all has different taste but a great amp is great amp.
I do not say your GM Minesis bad or other mosfet amp can't perform good.
I would not be interested on Fet or LFet anymore.
I still want to put together a Aleph2, and F5 high power and the basic F5 with Toshiba devices
You know I would live to hear my darlington amp with LMosfet
I do not pick the BJT over fet, darlington or tube!
One of my friend built the SEWA amp, he wrote how much better than the Zen4 or Zen9.
So I built it. I could not listen that amplifier in my system at all, all do I believe my friend has great ear and taste.
I did tried with different speakers and preamp, not my taste.
You know I will be still open and still believe mosfet amp can sound great!
Greetings Gabor
N Pass amplifiers are great!
You know Mark Finnish built at first the A40 and used over ## years.
After he built the Aleph5 and compared with.
He preferred the A40 he did missed the A40 when he listen his Aleph5.. After he built a Aleph4 thought his speaker need more power but on the end he realised not the speaker.
How you wrote it have to match (pick the right speakers) the system.Some amplifier it is easier to be matched into the system.
I'm not as fanatic to say I do like BJT and nothing else.
I like good sound, does not matter tube, BJT, HEXFET, LFet darlington etc.
To be honest darlington has a bit different sound (warmer, and faster) than BJT, at least to me!
I did listening PP tube amps, SE tube amp, mosfet amp BJT for years!
I would not say any of them just bad.
Do not misunderstand me please, the music to me not just bass. All do I like great bass.
If you ask Sakis any amplifier use Darlington it can't be good that his opinion, I did read that..
About the DX amp I didn't heard one so I can't comment.
But to me those devices Toshiba power transistors (so many of them are fake) or BD139/140 devices aren't my favorite..
I used those BD's in several circuit, when I replace them always I got sound upgrade.
I did used from Philips, ST etc.
The reason I didn't built the DX yet, probably I will never.
So many guy wrote how great the Symasym, so I built it at first test I knew that is not to me, not a keeper. I used all exotic parts
spent $$$ on parts.Well we all has different taste but a great amp is great amp.
I do not say your GM Minesis bad or other mosfet amp can't perform good.
I would not be interested on Fet or LFet anymore.
I still want to put together a Aleph2, and F5 high power and the basic F5 with Toshiba devices
You know I would live to hear my darlington amp with LMosfet
I do not pick the BJT over fet, darlington or tube!
One of my friend built the SEWA amp, he wrote how much better than the Zen4 or Zen9.
So I built it. I could not listen that amplifier in my system at all, all do I believe my friend has great ear and taste.
I did tried with different speakers and preamp, not my taste.
You know I will be still open and still believe mosfet amp can sound great!
Greetings Gabor
You know I would live to hear my darlington amp with LMosfet
I do not pick the BJT over fet, darlington or tube!
One of my friend built the SEWA amp, he wrote how much better than the Zen4 or Zen9.
So I built it. I could not listen that amplifier in my system at all, all do I believe my friend has great ear and taste.
I did tried with different speakers and preamp, not my taste.
Hehehe... if you cannot really understand your taste and its relation to circuit, and if you know that you like the darlington amp, I think you owe it to yourself to build the SSA, or any of the CFB amps. Hehehe what else can you use as a guidance? Believe me, some of us know the sound of a circuit simply from looking at the color of the PCB
Hehehe...
if you cannot really understand your taste and its relation to circuit, and if you know that you like the darlington amp, I think you owe it to yourself to build the SSA, or any of the CFB amps. Hehehe what else can you use as a guidance?
1)Believe me, some of us know the sound of a circuit simply from looking at the color of the PCB
Hello
I wrote I did built similar amp the Megalith in Class A, it was not a keeper!
The Profet far better amp!
1)These is one of the biggest lie was written on the forum or just simple the biggest joke!
Even the sim result and the listening result not 100%!!!!
Come on please let s remain at the reality
I tested so many similar amp I do not want waste time on the SSA,but because you bugging me probably I'll test it.
Min. I chose JFet on the input. That was a big improvement in may amplifier when I replaced the BC550/560
Which SSA better Sawn or the Nico type???
Greetings Gabor
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Okay, it seems you like the sound of JFET
The CFB has low PSRR and the JFET is low noise. Often you need a very good power supply filtering. But the Megalith uses battery so no issue, unless you didn't build it using battery? (I believe so )1)These is one of the biggest lie was written on the forum or just simple the biggest joke!
Even the sim result and the listening result not 100%!!!!
Come on please let s remain at the reality
I tested so many similar amp I do not want waste time on the SSA,but because you bugging me probably I'll test it.
You are the one who praised the darlington CFB amp!
Yes I know it is class-A, but you can make heavily biased T/SSA, like the one made by Sonnya. Most people I believe will prefer Sonnya's version. That's if you want to build your last solid state amp But you haven't built even F5, have you???Which SSA better Sawn or the Nico type???
For beginners, Shaan version is easier to get the bias right. Nico's version is more professionally build. But if you're an experienced builder, it doesn't matter which, they have the same topology and you may come to different setting, or cross between the two. In terms of operating point, I think I prefer Shaan's, but I never used the same circuit. I'm after higher power with latfet. For low power I have class-A.
Your darlington circuit has a good characteristics for heavily biased version. I believe it will "work" (tho not professionally) with latfet, where you can decrease the feedback impedance. In my book they are all the same topology.
Hello
I do not praise the Darlington, I just wrote the simple facts.
Believe it or not that not makes me happier or frustrated.
I didn't wanted to write about that amp (not even mentioned here) in these thread at all.
To be honest I didn't built the F5 yet (it is a reason, it was compared with the ProFet)
It is not much better at least not with IRF type mosfet, please do not argue over these.
I didn't made the test or these statement not from me. I didn't heard the test!
Reason I'll build my F5 with Toshiba devices.
You right the SSA low power (40W max or less). I think the same way like you, if low powered at least must be Class A.
I'll ask Sakis if he compared to the P3A which one he likes better..
I just don't know why nobody tested JFet in the SSA?? Can be replace one in one no need any mode for the 2SJ74BL/2SK170BL
Just need to be turned 180 degree.
Sound way better than BC550/560.
How much experience do I have? At least 22-23 years. Way over 100 amplifier built or built and just tested. I do not talk about I helped a guy in a TV shop 3 years and repaired a lot of commercial amp to. All do I'm not a technician.
Again I did biased the darlington up to 3A and just little improvment.
It does not worth to take all that heat for that little improvement.
Around 400-500mA sound excellent, but even under 100mA sound very nice.
With low bias it has less problem with the thermal runaway.
The Megalith I built with normal PS not with battery.
Even Ruiz built that amp to his friend with normal PS.
I believe if battery powered is better but that much, no I don't think so
Did you built any KSA clone??
Greetings Gabor
I do not praise the Darlington, I just wrote the simple facts.
Believe it or not that not makes me happier or frustrated.
I didn't wanted to write about that amp (not even mentioned here) in these thread at all.
To be honest I didn't built the F5 yet (it is a reason, it was compared with the ProFet)
It is not much better at least not with IRF type mosfet, please do not argue over these.
I didn't made the test or these statement not from me. I didn't heard the test!
Reason I'll build my F5 with Toshiba devices.
You right the SSA low power (40W max or less). I think the same way like you, if low powered at least must be Class A.
I'll ask Sakis if he compared to the P3A which one he likes better..
I just don't know why nobody tested JFet in the SSA?? Can be replace one in one no need any mode for the 2SJ74BL/2SK170BL
Just need to be turned 180 degree.
Sound way better than BC550/560.
How much experience do I have? At least 22-23 years. Way over 100 amplifier built or built and just tested. I do not talk about I helped a guy in a TV shop 3 years and repaired a lot of commercial amp to. All do I'm not a technician.
Again I did biased the darlington up to 3A and just little improvment.
It does not worth to take all that heat for that little improvement.
Around 400-500mA sound excellent, but even under 100mA sound very nice.
With low bias it has less problem with the thermal runaway.
The Megalith I built with normal PS not with battery.
Even Ruiz built that amp to his friend with normal PS.
I believe if battery powered is better but that much, no I don't think so
Did you built any KSA clone??
Greetings Gabor
I understand. My point is that if you like the sound of the circuit you may want to find out what parameters responsible for that sound.
I didn't try to convince you of anything. I have built many variations of NP amps. The difference is, nothing is ever a surprise for me anymore.
T/SSA is suitable for high power class-A: the distortion doesn't go exponentially with increasing voltage and frequency (like F5).
Very good idea!
I have simulated and yes it is possible. SSA is very symmetrical and require symmetry. Most PJF do not match NJF well. I like BJT than JFET, from dynamic point of view.
My simulation showed that the extra bias is required only for high power listening. Especially with such a very high gain setup you don't need it.
Yes. After that I'm convinced that both emitters of double EF outputs meeting at the output will create "terrible" sound.
Because the other topologies that we can see here and there are recent.??..
Btw, the amp discussed in this thread has as much as 30dB lower
harmonic distorsion residuals at 1khz than the Goldmund Mimesis....
It seems that there s some kind of irrationnal CFB mania that makes
people trust what is actually myths and are left worshipping amps like
tHe Grand Mos , wich has extremely high THD levels such that i wouldnt even
call it HiFi according to current standards , but for some people , no matter
the perfs providing it s a CFB , then it is automaticaly good even if the numbers say completely otherwise.
Same goes for the F5 whose Intermodulation distorsion is huge while
THD ratios are on on par with amps from the 50s/60s , but why complain ,
surely that it "sound good"..
Hello Jay
1) I would love to know that me to
2) No need to convince I'm working on at these moment 4 NPass amplifier.
The Aleph2, A40, F5 low power (one pair Toshiba 2SJ201/2SK1530) from 17-18V rail voltage.
F5T V1 with 4 pair Toshiba 2SJ200/2SK1529. I have A 24-0-24VAC 820VA transformer for these project. Need some resistors and right now I work on the enclosure of the amp.
Pass amplifiers are great.
3) That is what I heard, the amp sound excellent biased for a few Watt in to Class A. Even with low bias sound great!
With the right PS and 2 par BDW83C/84C you can get 100W at 4 Ohms.
The amp has more power my speaker can handle.
4) Very bad to know because I have a set stuffed boards.
Thank you
I started to work on the layout of the latest LFet amplifier wahab came up.
Greetings
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Do you have any intermodulation distorsion measurements of the F5 to
support this statement ? (haven´t seen any yet.)
Only simulations but that s accurate enough to give the trend.
I made a comparison of simulated perfs and the F5 is in line with
what can be extracted from the topology given the components
limitations.
http://www.diyaudio.com/forums/solid-state/173094-diy-audio-popular-amps-simulations.html