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VSSA Lateral MosFet Amplifier

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Esperado

Esperado

Banned
Joined 2011
esperado.fr
analog_sa said:
Many thanks. This answers all my questions. Will get the original reg back in place and report. Difference between the two halves of the ALF is still disturbing...
Click to expand...
As i said, N & P devices are not the same.
In my models, 2SK1058 need 1.4V, while 2SJ162 need -0.92V. for the same 160mA.
Yes, the reg voltage is gate to gate (so, in my sim 2.32V.)
1.25V of TLVH431 is perfect: it was unbelievable L.C. made such an error to use a 2.5V Zener. Everything is perfectly clear, now.
 
Lazy Cat

Lazy Cat

Member
Joined 2007
analog_sa said:
Blew up a power device. Replaced it. Now, even at the lowest voltage of the bias spreader - 2.5v - there is too much current through the outputs - about 360mA. Scratching my head...
Click to expand...

Hi :wave:

VSSA PCB from GB went into smoke? Very rare occasion hehe :hot:

Amp is so simple that the problem can be detected in 5 min and repaired in another 5 min if the board was not in flames. :magnify:

And yes, bias regulator is TLVH431. ;)

Regards L.C. :cheers:
 
analog_sa

analog_sa

Member
Joined 2002
Lazy Cat said:
Amp is so simple that the problem can be detected in 5 min and repaired in another 5 min if the board was not in flames. :magnify:

And yes, bias regulator is TLVH431. ;)
Click to expand...


Agree. Overlooked the tlvh prefix completely and the 5 minutes stretched into... rather not say :)

But on the plus side got to take down the transfer curves of both complementary devices and found they are not alike at all. Even at very low currents.
 
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G

gaborbela

Member
Joined 2005
LC I see you used 3 different caps (for testing)
Panasonic FC
Muse KZ
Nichicon Gold
Can you give me a short notice on the end why you picked Nichicon Gold
How those caps influence the sound of the amplifier
Please let me know, of course from other GB member who tried different caps your opinions are welcome to!
Thank you very much
Greetings G
 
Esperado

Esperado

Banned
Joined 2011
esperado.fr
gaborbela said:
How those caps influence the sound of the amplifier
Click to expand...
Caps are not perfect. They have serial and inductive parasitic properties, not always linear, depending of the currents and frequencies. Depending on the way they are manufactured.
Those parasitic properties influence the way they are able to stock and give back currents. And their impedances.
So they have an influence on phases at low and high frequencies, levels of AC signals depending of their frequencies, and the dynamic behavior.

Once you have designed an amplifier with theoretical values, and because the real behavior of a given electrolytic cap is difficult to sim, the best way is to do what L.C had done: Try and compare, both measuring and listening.
 
Lazy Cat

Lazy Cat

Member
Joined 2007
kp93300 said:
Hi
Re : VSSA and SMPS power supply .

I want to know whether the issues of the R19 and R20 has been taken care off in the second batch of the group buy pcb?

thanks

kp93300
Click to expand...

kp93300 said:
The atatched BOM ---want to confirm that the BOM is for one channel only.

Thanks

kp93300
Click to expand...


R19, R20 are in recomendation to be replaced with pulsed current ones. But according to the last shootout test I would recommend to shorten serial diode D5, D6 and resistor R19, R20 with short wire. There is an improvement noticed in bass region if serial R-D is shortened.

The BOM is of course for one channel only.

Regards, L.C.
 
Esperado

Esperado

Banned
Joined 2011
esperado.fr
Lazy Cat said:
There is an improvement noticed in bass region if serial R-D is shortened.
Click to expand...
May-be replaced with little cap multipliers or little high voltage regulators ICs ? It is only 15mA.
Both can give better common mode riple rejection than any LTP and improve dynamic, on my experience. And, of course, differential PSRR as well.
Worth a try ?
 
Last edited:
K

kp93300

Member
Joined 2007
Hi LC
Thanks for the reply.
I quote

"R19, R20 are in recomendation to be replaced with pulsed current ones. But according to the last shootout test I would recommend to shorten serial diode D5, D6 and resistor R19, R20 with short wire. There is an improvement noticed in bass region if serial R-D is shortened."

Unquote

Do you mean to short these 4 points --- R19, R20, D5 and D6 with a short wire at each component if using smps power supply?

kp93300
 
ichiban

ichiban

Member
Joined 2004
Paid Member
They look like a good fit to me.
The case diameter on the 2200uF/6.3V is 10 mm
which is even smaller than the recommended cap.
so even better fit.
The Lead Spacing and External Widths are the
important specs. All good.

Capacitor dimensions for VSSA PCB:

- 10 uF/63 V, MKT, Vishay-Roederstein, 2 pcs
Lead Spacing: 15 mm
External Depth: 8.5 mm
External Height: 17.5 mm
External Width: 18 mm

- 2200 uF/6,3 V, FG, Nichicon, 2 pcs
Mfr. #: UFG0J222MHM
Lead Spacing: 5 mm
External Diameter: 12,5 mm
External Height: 25 mm

- 1000 uF/50 V, FG, Nichicon, 4 pcs
Mfr. #: UFG1H102MHM
Lead Spacing: 7,5 mm
External Diameter: 16 mm
External Height: 31,5 mm

kp93300 said:
Hi
Can someone confirm whether the panasonic FC caps fit the pcb in terms of spacing for the lead and the overall diameter of the caps
EEUFC1H102 - PANASONIC - CAPACITOR, 1000UF, 50V | element14 Malaysia

EEUFC0J222 - PANASONIC - CAPACITOR, RADIAL, 6.3V, 2200UF | element14 Malaysia


thanks

kp93300
Click to expand...
 
Esperado

Esperado

Banned
Joined 2011
esperado.fr
kp93300 said:
Do you mean to short these 4 points --- R19, R20, D5 and D6 with a short wire at each component if using smps power supply?

kp93300
Click to expand...
Each R+D assemblies, they are in serial, just shorted. Means the current sources and VAS directly connected to the main rails. Something you can compare, listening, in your real build.
Doing this will reduce PSRR of the amp, so, greatly depend of your used PSU.
 
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