All Hitachi Lateral Fet amplifier for DIY described by Paul Kemble

[wahab]

While we are it , THD plots at 4W RMS/8R for 1 and 10Khz as well
as IMD 400HZ + 7KHZ ..

The noise floor is traced as reference.

Contrary to simulations at high frequencies , low power sims
wont exhibit high frequencies residuals.

Actually , the simed THD at high power is likely higher than
in real world for higher order harmonics.

[gaborbela]

Thank you wahab
Today I was busy with a class A amplifier enclosure..
Soon I order the resisters and transistors.
At Newark they have Dale 1/2W resistors 26Cent/each.
I need to ad together the values I need for all the half ready amplifiers and after I do the order.
I see on Ebay Jims Audio sell bare PC boards for Goldmund Telos (not cheap) but people buy it because the name..
If people wont build these amp I think not because these or that measurement missing, because does not have the NAME! like GM so on and so on
I like these amp a lot, it will be great replacement (upgrade)for the Grand Mos..
How I wrote some people followed the thread specially when Alex worked on the layout only for............................ not to build etc..
No problem, I'm more than happy with these amp..
I see you put your hart in to these amp, thank you.

Greetings Gabor

[wahab]

Originally Posted by gaborbela

Soon I order the resisters and transistors.
At Newark they have Dale 1/2W resistors 26Cent/each.
I need to ad together the values I need for all the half ready amplifiers and after I do the order.

Hi , Gabor

Those resistors are not cheap at all for such basic components...

The currents are tailored such that most resistors could be 1/4W , there s
only a few that should better be 0.5W for long term reliability.

Originally Posted by gaborbela

I see on Ebay Jims Audio sell bare PC boards for Goldmund Telos (not cheap) but people buy it because the name..
If people wont build these amp I think not because these or that measurement missing, because does not have the NAME! like GM so on and so on
I like these amp a lot, it will be great replacement (upgrade)for the Grand Mos..
How I wrote some people followed the thread specially when Alex worked on the layout only for............................ not to build etc..
No problem, I'm more than happy with these amp..
I see you put your hart in to these amp, thank you.

Greetings Gabor

Readily availaible PCB has surely to do with it but also the hype around the Goldmund was and is still so strong that people wont pay attention that it is not up to the CD standard by a large margin, never mind , it is said to "sound good" even if its harmonic/intermodulation distorsions (in meddle band , where the ear is most sensitive) are something like 50x and 100x what they are for this amp and at least 10X if not more than the one of a very average CD player.

In fact , it cant even keep up with MP3 files fidelity once the bit rate is above 256kbits.....

As for the amp in this thread , the only concern i had was the VAS as it works up to 130Mhz for its local compensation loop , hence extremely short tracks for this circuit part are mandatory , as nicely done in your PCB.

Anyway , this home made PCB will give better perfs than most designs
that hang by there and particularly the recently hyped ones , amongst
them the GM.

True that sims are not 100% accurate but they have way enough precision
to highlight the differences between schematics and in this respect even
if i cant provide hard numbers it s no surprise that the most marketed
amps in this forum neither bring measurements nor simulations , for some
obvious reasons, only claims of "good sounding" as a convenient "parameter" to dismiss simulators that put them in an uncomfortable position.....

Just let you wondering if good perfs is really a concern , after all
inexistent features are even claimed in some "designs"....

[Jay]

Originally Posted by wahab

True that sims are not 100% accurate but they have way enough precision
to highlight the differences between schematics and in this respect even
if i cant provide hard numbers it s no surprise that the most marketed
amps in this forum neither bring measurements nor simulations , for some
obvious reasons, only claims of "good sounding" as a convenient "parameter" to dismiss simulators that put them in an uncomfortable position.....

Just let you wondering if good perfs is really a concern , after all
inexistent features are even claimed in some "designs"....

If you're wondering why...

Simulation can show many things, not only what you have shown. Many things... From those things, each of us have a unique way to predict amp performance.

SSA BIGBT HP also simulated well. And LazyCat likes it a lot...

Until now I don't understand the mystery behind cascaded VAS. It brings an outstanding "technical performance" but not everyone go that route (I don't either). Like you said, makes you wondering if good performance is really a concern...

I tried simulating my Goldmund clone input stage with your VAS and output stage. Cool, the H2 for my listening level is below -120dB! (and monotonic spectrum). From that point of view: magnificent! Unfortunately, it didn't pass my overall standard.

I didn't simulate your schematic because I don't have the VAS transistors models. Didn't bother to find it on the net because I would never used it anyway (because I build using parts from my inventory only).

[wahab]

Originally Posted by Jay

Simulation can show many things, not only what you have shown. Many things... From those things, each of us have a unique way to predict amp performance.

Would be great to know what are those "things" that didnt show up
and wich can predict amp performance in another way that the sims
i posted....

Originally Posted by Jay

SSA BIGBT HP also simulated well. And LazyCat likes it a lot...

Would be also great to see thoses sims graph as well ,
unless they are also treated as a "thing" with no dimension.
That Lazy cat likes it a lot has no technical value , this is not
even a worthy argument with all the respect i have for him, you ll easily concede it....

Originally Posted by Jay

Until now I don't understand the mystery behind cascaded VAS. It brings an outstanding "technical performance" but not everyone go that route (I don't either). Like you said, makes you wondering if good performance is really a concern...

I tried simulating my Goldmund clone input stage with your VAS and output stage. Cool, the H2 for my listening level is below -120dB! (and monotonic spectrum). From that point of view: magnificent! Unfortunately, it didn't pass my overall standard.

Like the undefined "things" above , what are your standards?
More THD/IMD and poor PSRR than this amp can provide?..

Originally Posted by Jay

I didn't simulate your schematic because I don't have the VAS transistors models. Didn't bother to find it on the net because I would never used it anyway (because I build using parts from my inventory only).

There are other transistors that suit the task , i mentionned it ,
among other the BF469/470 and BC550/560 for the common emitter part....

As for me , i simulated almost all amplifiers of this forum since my own standard is to check the caracteristics rather than relying on a pseudo technical discourse when giving an opinion about a design.

[gaborbela]

Originally Posted by Jay

If you're wondering why...

I didn't simulate your schematic because I don't have the VAS transistors models. Didn't bother to find it on the net because I would never used it anyway (because I build using parts from my inventory only).

Hello Jay

Wahab gave me a list for VAS I can use, I picked the Toshiba because that cheaper and available..
But that not mean if I get the Sanyo transistor for good price I will not pick those over the Toshiba.
I'll post the list for the VAS he gave me soon may be you can find more info from the Sanyo..
I would not use BF or any transistor from CDIL or ISC under any circumstances.
In my darington amp the BF sounded so bad compare the old BF (I think it was made by Philips) I can't explain to you.
I will use Sanyo, Toshiba, Hitachi etc nothing from India from CDIL.
ISC BDW83/83D type (D stronger than the C type) blew up in my amp with low bias before the amp warm up at 45C..20-30 min and blew up.
The BDW93/94C from ON semi (half the power) with higher bias worked well!!
That is about CDIL and ISC..
I'm a big fan of the Goldmund but the Telos not what was built by you.
Each mosfet has own driver that type. Hard to find the input JFet...
More than 4-5 years I'm looking for PC board for that amp now available but I'll build these amp!!!
I Never heard the sound that Telos ,but I like the circuit, I'll look up the circuit and I posted, I think that PC board has now these guy at ebay.
It cost a arm and a leg the new..
Also there is a other amp on ebay some famous Marantz clone with Toshiba outputs.
I like that circuit to a lot, but I would not use fake Toshiba....

Greetings Gabor

[EDDELARUE]

Originally Posted by wahab

While we are it , THD plots at 4W RMS/8R for 1 and 10Khz as well
as IMD 400HZ + 7KHZ ..

The noise floor is traced as reference.

Contrary to simulations at high frequencies , low power sims
wont exhibit high frequencies residuals.

Actually , the simed THD at high power is likely higher than
in real world for higher order harmonics.

Why you don't use "db" scale ?

[gaborbela]

I forget
If I remember you wrote at the beginning of these thread no way these amp will exceed the performance of the Grad mos (something like that)
What if these amp will outperform the famous GM clone you built??
After wahab test it will do outperform that Goldmund.
Of course real life a bit different but still sim gave a lot of idea about the amp performance.
I do believe is a real chance these amp sound as good or better than the famous GM clone.
After Sakis P3A test the Goldmund was nowhere when was compared with the Eliot amp.
Of course different taste different vine. How Sakis wrote it was an old experienced audiophile man with the Goldmund clone..
I would still pick the Telos over the Mimesis clone you guys built.. After the circuit!

Greetings Gabor

[wahab]

Originally Posted by EDDELARUE

Why you don't use "db" scale ?

Well , the conversion in db is straightforward but true that most people
are used to dB , so next time i ll use this reference....

[gaborbela]

Hello
wahab I have a question to you
I have 10pair Hitachi 2SB649A/2SD669A C type at home. Can I use those some place in these amplifier for cascode etc?
http://ampslab.com/Freewares/2sb649a.pdf
It look like not bad transistor (to me better than BF)
In case you would advise not to use them not a problem!
For VAS I'll buy the best, I didn't had time to look around here in Toronto at the local store until now.
Greetings Gabor