VSSA Lateral MosFet Amplifier

[Esperado]

But i think we can continue this in the CFA thread.

I'm not sure we can: Thread closed !!!
It seems CFA is a very sensible subject. Something like to pretend the earth is round.
I will not make comments about this forum neither about the Roman Inquisition.

 

[wewe]

Hi LC need a help with my VSSA

I have bild and everything was ok.
By mistake got some dc from comp soundcard out( have not input cap) and R21-20ohm smdis now open.I dont see any 20ohm resistor on ESL0113 rev1.4 schematic, but it is on BOM. Where is right schematic?
Regards

 

[Lazy Cat]

Hi Andrej Is this the amending to be done, or is there more meant in that statement from post #2245 qoute "VSSA improvement will be detaily described after all VSSA modules will be shipped out", just curious if D5/D6/R19/R20 are the baby for that improvement, or more is published when shipping is done.

About this D5/D6/R19/R20 shortening do you recommend one to make sound listening test with original setup first, and then do the shortenings with sound listening test to compare. Or is it recommended to jump to shortening setup righting the R19/R20 fast pulse problem in same amend.

Yes, this change is a major part of a recommendation meant to be proposed to VSSA owners, either SMPS or conventional PSU is used.

To be sure the change will actually bring a valuable improvement in SQ, try to compare original and shortened R-D version. 😉

 

[Lazy Cat]

I have bild and everything was ok.
By mistake got some dc from comp soundcard out( have not input cap) and R21-20ohm smdis now open.I dont see any 20ohm resistor on ESL0113 rev1.4 schematic, but it is on BOM. Where is right schematic?
Regards

Actually there are two 20 Ohm resistors in output Zobel filter. It simply got too much power dissipation in higher spectrum since it is in series with 47 nF. Probably measuring method at 20 kHz lasts too long and ...

 

[Idefixes]

Yes, this change is a major part of a recommendation meant to be proposed to VSSA owners, either SMPS or conventional PSU is used.

To be sure the change will actually bring a valuable improvement in SQ, try to compare original and shortened R-D version. 😉

Hi LC could you locate in a picture the better way to do this?

Marc

 

[ichiban]

D5/D6/R19/R20 shortening .........jumpers....

 

[pinnocchio]

Ichiban,

Is it better to remove the parts as well or just jumper is ok?

Thanks
Do

 

[analog_sa]

Only if you want to reuse them 🙂

I wonder how doable would be to feed everything past the outputs from a separate PS. Probably issues with power-on transients...

 

[ichiban]

Ichiban,

Is it better to remove the parts as well or just jumper is ok?

Thanks
Do

This is best asked of Lazy Cat , but I think he says shortening (jumpered) in order to do a comparison. 🙂

 

[Lazy Cat]

D5/D6/R19/R20 shortening .........jumpers....

Thanks ichiban, correct jumpers placement.

There's no need to remove R-D parts since you can go back any time if the change is not satisfactory.

It would be nice to hear responses about this change from GB members.

Regards L.C.

 

[Idefixes]

Thanks all for details.

Marc

 

[Esperado]

It would be nice to hear responses about this change from GB members.

Hi, L.C.
Did-you made sure the improvement you noticed was not due to the add of the lytics to the main power Rail ?
By example strapping D+R, as you did, cutting the VAS+Input track, and use a regulated/cap multiplier to power them separately ?
This really question-me.

 

[BenY]

There could be improvement due to the cancelation of diode. Diode switching due to suckout differeces on two sides of each rail injecting switching noise also at power supply freq ripple.

 

[BYRTT]

Because thread is long for members to decode all good hints and errors i try make some check list as a helper for overview of building.
Checked all links are live working before posting, if missing something or errors please post.

Important info for setup of VSSA:

1-Installation manual. (Post #1869 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-187.html#post3560379)
2-VSSA Installation manual correction. (correct calibration ajustments) (Post #1371 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-138.html#post3514964)
3-Desolder R23 and replace with short, see attached picture. (Input ground lift amend) (Post #1963 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-197.html#post3568278, and alternative on other side of PCB Post #1971 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-198.html#post3568597)
4-Caps physical dimensions to use before ordering. (post#1404 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-141.html#post3517143)
5-Exchange R19/R20 with Multicomp MCPWR10FTFQ0100 or Vishay if using speedy PSU mostly SMPS, or do "point 2" in next chapter. (Post #1809 Multicomp link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-181.html#post3549545 and Vishay Post #1799 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-180.html#post3548500)
6-VSSA recommended grounding connections helper v1.1. (Post #1700 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-170.html#post3543127)
7-Member sng001 explain smart way to pre-adjust TR1/TR2/TR3 before powering first time, and to calibrate with just one DMM. (Post #1561 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-157.html#post3532755)
8 Soft start if using recommended Hypex SMPS400A180 and short of NTC on Hypex PCB. (Post #1937 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-194.html#post3567294)
9-Pre/Early circuit BOM can be used if circuit goes smoking or you physical break/destroy some component then good reference for component exchanges. (Post #705 link http://www.diyaudio.com/forums/vend...-lateral-mosfet-amplifier-71.html#post3417406)
10-Pre/Early circuit schematic v1.4 can be used for debuging. (Post #300 link http://www.diyaudio.com/forums/vend...-lateral-mosfet-amplifier-30.html#post3314786)

Info for setup of VSSA (Maybe need sound listening test for personal preference):

1-2,2mF feedback cap can go alone without 10uF MKT if prefered. (Post #1424 link http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-143.html#post3522324)
2-Shorting both R19/R20 and D5/D6 for sound improvement (Phycical change Post #2526 http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-253.html#post3652831 and explanation Post #2501 http://www.diyaudio.com/forums/vend...lateral-mosfet-amplifier-251.html#post3651203)

 

[audiostar]

Is there a website or blog for the VSSA amp?

 

[kp93300]

Hi BYRTT
Thanks for the info in post 2534. Much appreciated .

Hope LC can include these info into the first thread.

regards
kp93300

 

[atupi]

Big thank you BRYTT for this helpful post as i'm preparing to start building the VSSA kits.

 

[analog_sa]

Resistors and diodes shorted - improvement is quite substantial, especially in the bass, which until now has been the weakest feature of VSSA.

I also learned that Black Gate caps are not a good sonic match for the input stage.

Mine is a very modest build with a single 500VA linear supply shared between the channels. Even so, it is very, very good. Thanks Lazy Cat 🙂

 

[Idefixes]

I will test this modification too as for me bass region is the weakest feature too.

Marc

 

[Lazy Cat]

Thanks for your opinion analog_sa, appreciate it a lot. I'm glad that the change represened itself in a same way as here. Enjoy your "new" amp.