All Hitachi Lateral Fet amplifier for DIY described by Paul Kemble

[wahab]

Originally Posted by gaborbela

Yes I'll go with 3 pair power mosfet, I have a transformer 40-0-40VAC 750VA or I share the transformer with my Aleph2 2PC 39-0-39VAC 600VA/each.
The transformer I'll use will depend on the bias req. of the amplifier.
I'm not sure what would be the right bias (VA rating of the transformer) I do not want another Class A only the first couple Watt

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.

Originally Posted by gaborbela

Also I would live to get some opinion how would you com pare these amp to these symmetrical
These use 52V rail Voltage 400mA bias/channel.. The reason I ask because I have these amplifier (stuffed PC boards) but I read symmetrical has problem when is not matched well the N channel to P channel devices.
Those drivers is impossible to be matched!

Greetings Gabor

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.....

[AndrewT]

Originally Posted by wahab

................. with 3 pairs
and a total current of 300mA this allow to have pure class A up
to a few watts..............

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.

[gaborbela]

Originally Posted by Jay

One thing that you may have missed is...

You have liked a darlington CFB amp before. Why not build another CFB, but a better one (because darlingtons have bad reputation anyway). Pay attention to the feedback configuration of the Grand Mos. It is preferable than the LTP. The problem with the FET VAS is only the drive for the output mosfet.

Why not build another CFB amp, such as the SSA, may be you will like it better than your VFB amps.

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

[Jay]

Originally Posted by gaborbela

Hello Jay
Are you talking about my Darlington amplifier?? I posted about 2 years a go,

Yes, that one. Basically it is an SSA without the input cascode.

Originally Posted by gaborbela

Built and tested over 100-120 amplifier (from N Pass, Symasym, Gainclone P Daniel, Hiraga both,so on)!

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..

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.

Originally Posted by gaborbela

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!

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.

Originally Posted by gaborbela

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.

Originally Posted by gaborbela

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!

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.

[gaborbela]

[QUOTE=Jay;3205477]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.

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. QUOTE]

[gaborbela]

Unfortunately took to long time to answer (edit) so I lost my post.
I'll rewrite tomorrow.
Greetings Gabor

[gaborbela]

Originally Posted by Jay

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

[Jay]

Originally Posted by gaborbela

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.

Originally Posted by gaborbela

I wish someone from the forum would hear the sound of these amplifier.

I have heard many SSA variations: darlington, latfet, bjt, hexfet...

Originally Posted by gaborbela

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.

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.

Originally Posted by gaborbela

I'll build the A40 which use also darlinton power transistors probably that.

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.

Originally Posted by gaborbela

About the GM Minesis clone Sakis wrote the Elliot P3A much better amplifier!
So what can I write now..

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...

[gaborbela]

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

[Jay]

Originally Posted by gaborbela

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