VSSA Lateral MosFet Amplifier

[gogu]

Hi LC,
I am in for a Stereo set of PCBs.

 

[gaborbela]

They're not the same, here we have CCS supplying input bias current plus ALF mosfet plus special layout, huge differences speaking of SQ.

Hello

All my respect to your work you done with these amp!
We only can talk about difference (SOUND WISE) between the two when someone do a listening test like A-B test.
Otherwise I agree you took it further the topology, you improved the stability so on and on.
On the other hand on one think I'm a bit sceptical..
Mosfet tend to sound soft specially in bass area (shy). At least that is my experience or some other DIY-ers report the same.
Believe me I built several mosfet and BJT amp the last 2.4 decade or so. Please do not misunderstand I do like the good mosfet sound! Even now I work on a Hitachi mosfet amp project..
Very soon I can test your amp next to mine, I hope I (we) still get the type mosfet U use.
The main reason I go with regular parts and not SMD, I think only it would be fair to compare the two amp if I use the same resisters even do probably someone pick the SMD types over the regular and say those are better because........... but not necessary..
So soon I will compare the two amp, next to each other..
O course all my credit to you because what you achieved with these topology..
And you made it very popular among the DIY-ers..

Greetings G

 

[wahab]

You are correct. It isn't the same. The new one has some refinements. Great job.

Actualy the last Gabor versions have CCSs , even if it s
basic CCSs using a zener and a couple resistors.....

 

[FelixG]

Hallo LC,
please be so kind to take me on the list for 4 sets of pleasures.
thanks

 

[Tyimo]

Lazy Cat!
How can I set (adjust) the bias higher?

Tyimo

 

[de Ocampo]

Keep an eye on the index.

Hi Shaan,

I'm all eyes on the forum..

TY!

 

[joshvi]

Hi LC,
I am in for a pair of PCBs.

 

[Esperado]

Lazy Cat!
How can I set (adjust) the bias higher?
Tyimo

I recommend-you to not do that. There is a point where MOSFETS are optimal (for linearity/temp), and L.C. knows how to bias them at optimum..

 

[philippeleite]

Hi LazyCat

Count me in for a pair of PCBs too.

Best regards.

 

[qusp]

with 'the wire' which is lme49830+ semelab/alfet dual die laterals, the point where distortion stopped improving noticeably was around 600mA, but that wasnt much better than 400mA

 

[Salas]

Its there where Sonny biases TSSA 1.6 too.

 

[qusp]

Owen said it did improve slightly at 1A, but at that point it was pure class A and only really capable of pulling 30WPC out of an amp and power supply capable of pretty much matching that performance at nearly 200W... not really a worthwhile trade-off. at 600mA 1khz 2nd harmonic distortion product is -110dB into 8Ω... H3 is ~ -118dB

 

[mefistofelez]

Hi LazyCat,

would like 4 boards.

Kindest regards,

M

 

[Tyimo]

What is the default bias level of the "original" VSSA?
How many mA?
And still the old question: how can I adjust it???

 

[Lazy Cat]

What is the default bias level of the "original" VSSA?
How many mA?
And still the old question: how can I adjust it???

Optimal output bias current is 160 mA. Other values according to personal taste of the user.

Procedure is simple, first solder 1 k multiturn trimmer potentiometer to R17 pads by the help of 2 cm wire for each trimmer's pin, start with zero ohm setting, trimm bias current to 160 mA, wait for the heatsink to warm up, readjust the trimmer to 160 mA, unsolder the trimmer, measure resistance of the trimmer with digital ohm-meter, use appropriate R17 SMD resistor size 1206 (3216) of the same value as measured, solder the resistor to VSSA PCB.

 

[Lazy Cat]

VSSA PCB requests

So far 126 VSSA PCB requests received. I'll post the ones from open forum (116 pcs), PM requests (10 pcs) will stay discrete. Next week I will send the info to each of you regarding sets (PCB + semiconductors).

Regards, Andrej

Joachim Gerhard 2 PCB set
AKN 2 PCB set
Idefixes 4 PCB set
kimon 2 PCB set
brianco 2 PCB set
Dane 2 PCB set
MKHunt 2 PCB set
Cambe 2 PCB set
Supernet 2 PCB set
boyet0173 2 PCB set
tom42107 2 PCB set
presbel 2 PCB set
meltman 2 PCB set
gannaji 2 PCB set
dodo 2 PCB set
coolet 2 PCB set
jj506 2 PCB set
vgeorge 2 PCB set
touchdown 2 PCB set
wponline 2 PCB set
Luke 2 PCB set
cvtaudio 10 PCB set
Renio 2 PCB set
maillard 2 PCB set
PauloPT 2 PCB set
hcbonfim 2 PCB set
gusto142 2 PCB set
PinkPink 2 PCB set
dine1967 2 PCB set
bressix 2 PCB set
nico2k3 2 PCB set
routhun 2 PCB set
CaféNoir 2 PCB set
ColinAlex 8 PCB set
Murdoc 2 PCB set
regal 2 PCB set
AUSTINP 2 PCB set
kroyin 2 PCB set
fredlock 2 PCB set
mikvous 2 PCB set
myfi 2 PCB set
FelixG 4 PCB set
ichiban 2 PCB set
padamiecki 2 PCB set
gogu 2 PCB set
joshvi 2 PCB set
philippeleite 2 PCB set
mefistofelez 4 PCB set

Thanks a lot guys.

 

[regal]

Thanks for including the semi's they seem difficult to obtain.

 

[DavorXXL]

Hi LC,
count me in for 6 PCB set

 

[sakdi]

Count me in for a stereo pair.

Best regards.

 

[buzzforb]

Regards, Andrej

Joachim Gerhard 2 PCB set
AKN 2 PCB set
Idefixes 4 PCB set
kimon 2 PCB set
brianco 2 PCB set
Dane 2 PCB set
MKHunt 2 PCB set
Cambe 2 PCB set
Supernet 2 PCB set
boyet0173 2 PCB set
tom42107 2 PCB set
presbel 2 PCB set
meltman 2 PCB set
gannaji 2 PCB set
dodo 2 PCB set
coolet 2 PCB set
jj506 2 PCB set
vgeorge 2 PCB set
touchdown 2 PCB set
wponline 2 PCB set
Luke 2 PCB set
cvtaudio 10 PCB set
Renio 2 PCB set
maillard 2 PCB set
PauloPT 2 PCB set
hcbonfim 2 PCB set
gusto142 2 PCB set
PinkPink 2 PCB set
dine1967 2 PCB set
bressix 2 PCB set
nico2k3 2 PCB set
routhun 2 PCB set
CaféNoir 2 PCB set
ColinAlex 8 PCB set
Murdoc 2 PCB set
regal 2 PCB set
AUSTINP 2 PCB set
kroyin 2 PCB set
fredlock 2 PCB set
mikvous 2 PCB set
myfi 2 PCB set
FelixG 4 PCB set
ichiban 2 PCB set
padamiecki 2 PCB set
gogu 2 PCB set
joshvi 2 PCB set
philippeleite 2 PCB set
mefistofelez 4 PCB set
buzzforb 2 PCB set