VSSA Lateral MosFet Amplifier

[Lazy Cat]

Maybe something to investigate in the future. I think Bruno Putzey's company in the Netherlands is doing
400W and 700W SMPS unreg for very resonable prices (bare board).

Two unregulated SMPS400 that I have in the last VSSA prototype are from Hypex.

 

[Lazy Cat]

Note to all GB members

VSSA has been so well tested and its performance is up on the level expected to be good enough for all of you.

Over the weekend I will prepare new gerber files for a mass production VSSA PCB. This one will include all SMD parts as well as three SMD multiturn trimmers from Bourns for easy calibration adjustments of DC offset and output bias. Complete calibration procedure can be performed in less than 60 seconds, so really quick and very accurate adjustment to set your VSSA in perfect working conditions.

 

[Bonsai]

Two unregulated SMPS400 that I have in the last VSSA prototype are from Hypex.

Yes- those are the ones I am thinking about. What output power?

 

[Lazy Cat]

My measuremens of SMPS400 showed at 230 Vac mains:
- 2 x 45 V unloaded, 100 Hz saw ripple 100 mVpp
- 2 x 40 V loaded at 5 Aeff, 100 Hz saw ripple 1 Vpp
- 80 V x 5 A exactly 400 W output power

In short this measurement was better than of the same power level linear PSU.

 

[maxlorenz]

Dear LZ,

Can you still include me with 2 PCBs?

Joachim Gerhard 2 PCB set
AKN 2 PCB set
Idefixes 2 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 6 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 (no ALF)
gogu 2 PCB set
joshvi 2 PCB set
philippeleite 2 PCB set
mefistofelez 4 PCB set
DavorXXL 6 PCB set
sakdi 2 PCB st
buzzforb 2 PCB set
siberia 2 PCB set
mravlca 2 PCB set
baswamin 2 PCB set
miksi 4 PCB set <--correction
chunek 4 PCB set
raysimmons 2 PCB set
johnkrammer 2 PCB set
jony 2 PCB set
sng001 2 PCB set
atupi 2 PCB set
analog_sa 2 PCB set
davidhoang 4 PCB set
Malvin 2 PCB set
vitalica 2 PCB set
Andrewc556 2 PCB set
88bruce 2 PCB set
jkuetemann 2 PCB set
RAYSIMMONS 2 PCB set
Odysseas 2 PCB set
yassud 2 PCB set
Junie 2 PCB set
ivanlukic 2 PCB set
Telstar 2 PCB set (incl semi)
Maxlorenz 2 PCB set.

Thank you very much for all.
M.

 

[Telstar]

Supernet was also very sceptical about SMPS, me as well, but the sound reproduction clearly showed which one the amp itself likes more to be connected to

Yes, I have read his reply now.
Pity the feedback capacitors werent exactly the same (and I mean same model and measured capacitance and ESR to 1%). The FB cap is VERY critical for SQ. I wonder if he can repeat his test having only the PSU as variable.

 

[Esperado]

Very nice link Esperado - lots of great vintage gear! I remeber the Marantz 1040 very well - those were the days when they new how to make an amp.

One of my baby is here too

May-be worth a try to one regulated SMPS from Connex: http://connexelectronic.com/product_info.php/products_id/142?osCsid=3v54esa5m7lsulgftdq2au4j32

or two http://connexelectronic.com/product_info.php/products_id/148
http://connexelectronic.com/product_info.php/products_id/142?osCsid=3v54esa5m7lsulgftdq2au4j32

 

[Telstar]

Yes, Esperado, please do all these PSU tests, are very interesting.

 

[ashok]

It appears that the CF amp that Gaborbela and LC have been talking about appears to have pretty decent PSRR ( on simulation ) when you use a current source on the input transistors. So how come its 'sound' is so sensitive to the power supply noise / regulation .... SMPS or normal linear supply?
As we have just read from one of the testers the basic amp doesn't sound particularly exceptional with a simple bridge and capacitor power supply .

 

[Lazy Cat]

It appears that the CF amp that Gaborbela and LC have been talking about appears to have pretty decent PSRR ( on simulation ) when you use a current source on the input transistors. So how come its 'sound' is so sensitive to the power supply noise / regulation .... SMPS or normal linear supply?
As we have just read from one of the testers the basic amp doesn't sound particularly exceptional with a simple bridge and capacitor power supply .

It is not that VSSA is sensitive only to power supply, I measured around -100 dB PSRR, or its noise or ripple. Far from that. It was just confirmed in listening tests that so resolutive and transparent amplifier like VSSA is, clearly shows every little change in such a vivid way, that you can easily sense different speaker or interconnect cables, PSUs even more evidently, etc. That means it is very easy to find the best system combination as possible since amp shows you the right way to do it, like it would have "headlights" installed. That's what is all about in this VSSA thread and that was initially the aim to get super transparent and resolutive current feedback amplifier, when all correctly settled, to play purely music in full resolution.

 

[borys]

Sory for my stupid questions:
- does VSSA amp needs really so big heatsinks?
- how about thermal stability (bias) - is it ok ?

Big thanks

 

[Lazy Cat]

Sory for my stupid questions:
- does VSSA amp needs really so big heatsinks?
- how about thermal stability (bias) - is it ok ?

Big thanks

Not necessarily, for normal home use they're something like 30% oversized, as heat dissipation/temp clearly showed. But if someone would use them hard on 4 ohm speakers in long term loading programme they would be just right.

Thermal stability is 100% no issue in any circumstance, it is even a little NTC type of.

 

[borys]

THX for quick answer.

 

[Esperado]

Whatever perfect an amp can be, it will be as good as its power supply is.

 

[maxlorenz]

Whatever perfect an amp can be, it will be as good as its power supply is.

Amen.

Please note that there are two "SMPS400" power supplies: we want SMPS400A180.

Hope this helps.
M

 

[Lazy Cat]

Amen.

Please note that there are two "SMPS400" power supplies: we want SMPS400A180.

Hope this helps.
M

Amen to that too.

Exactly, +/- 45 V version of SMPS400.

Thanks maxlorenz

 

[31697B]

Is there a +/- 75vdc version ? I want to sub it into an existing amp to listen.

never mind -- i found them.... look good and price is reasonable. I'll have to give a try and espe see how they sound and how reliable they are.
Only concern is about switching freqs getting into analog circuit. And added hf/rfi on the ac power line.

Thx-RNMarsh

 

[maxlorenz]

Thanks maxlorenz

You are very welcome, sir.


Mr. Marsh wrote:

Only concern is about switching freqs getting into analog circuit. And added hf/rfi on the ac power line.

I imagine extra inductors won't hurt (?)
Since there are good caps on the PCB...
What is good practice?

Thanks,
M.

 

[ashok]

But surely with a Very transparent amp that will easily show up supply ripple and other issues , at -100dB PSRR there will be no noise to be heard. So what gives ? So looks like it is interacting in some way with the type of power supply that is being used.....like most amps I guess.

 

[supernet]

Some photos taken from listening session: