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VSSA Lateral MosFet Amplifier

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Lazy Cat

Lazy Cat

Member
Joined 2007
And this is how it looks when measuring with ARTA system.
 

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Lazy Cat

Lazy Cat

Member
Joined 2007
BYRTT said:
Hi Andrej very impressing control and specs you get with new diy-AP setup, i guess it is very fun/learning/satisfying and can be saved as knowledge librarary. Later tell if the tuning is more or less audioable.
If you think VSSA module could benefit this tuning, would it be possible to pay for the service done by you. Example i send you a mono module, you tune and post for VSSA owners, i pay and you send module return.
Click to expand...

Yes a lot of fun watching response on the monitor, any little change can make a difference so learning to use the system to get good results is very educational.

Also in general the ARTA measuring system just confirmed what I was doing before with just my Tek scope. Namely measuring amp's HF signal spectrum with 3 MHz carrier, tuning to lowest distortions has the same effect as now watching and tuning audio spectrum. HF compensation can make a lot of difference to THD and therefore the PCB layout comes into rule at this point as a general component of the amp, besides topology.

VSSA was also tuned to lowest HF distortion before releasing to GB, we could get something in between 5-8 dB THD improvement if implementing Cherry plus Miller compensation, but that would be more of academic act than real step forward to better sound. I think VSSA is somehow concluded project, not because there's no interest but because of 26 weeks lead time to get ALF mosfets. I would not even dare to think to go through the same path as I had with Semelab, so for me it is the end of the story.

Regards, L.C. :cheers:
 
Esperado

Esperado

Banned
Joined 2011
esperado.fr
Lazy Cat said:
but that would be more of academic act than real step forward to better sound.
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That it is what i presume, but did-you confirm-it by listening comparisons ?
Lazy Cat said:
but because 26 weeks lead time to get ALF mosfets. I would not even dare to think to go through the same path as I had with Semelab, so for me it is the end of the story.
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Don't they have solved this ? Or it-it just you are crossed against them because of this painful story ?

Happy Christmas, Andrej. Look under the Christmas tree, you will find my friendship and best wishes for this next year.
 
Lazy Cat

Lazy Cat

Member
Joined 2007
Esperado said:
That it is what i presume, but did-you confirm-it by listening comparisons ?
Click to expand...
As soon the second channel is finished, maybe this week. Will report here. ;)

Esperado said:
Don't they have solved this ? Or it-it just you are crossed against them because of this painful story ?
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I just checked with them and they said 26 weeks, that for any non contracted DIY operation is just too long and risky. Completely the other story with their N or P channels. :)

Esperado said:
Happy Christmas, Andrej. Look under the Christmas tree, you will find my friendship and best wishes for this next year.
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Thanks Christophe will do, Marry Christmas to you too and to all the guys here on the forum. :santa2:
 
Esperado

Esperado

Banned
Joined 2011
esperado.fr
Lazy Cat said:
I just checked with them and they said 26 weeks,
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It is build on demand, handcrafted by virgins, atom by atom.
Are-they crazy ?
I wonder why there is so few analog audio devices, near active devices manufacturers.
Fantastic CIs disappeared (Like my beloved OP260), we are still waiting for various paired complementary devices in one chip etc...
Their idea of power complementary laterals was clever, why did-they make-it unavailable ?

By the way, did-you project to show-us a schematic of your First one (without values, if you prefer) ?
 
BYRTT

BYRTT

Member
Joined 2009
Andrej thanks for answering the VSSA thoughts, and congratulation "First One" new state ready for market with beautiful specs.
Wishes a Happy Christmas to everybody here, member PMI worries my mind he and family gets exstra thoughts and wishes.
 
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H

hose4

Member
Joined 2013
amp kit

Dear Lazy cat!

As you know my Vssa project has been finished few months ago.
My new 1200W power supply is waiting for the new Xmas present.
I can hardly wait for the new boards and box.

BTW nice measurements. Did you try with different feedback caps? Would be nice too see if there is a change in spectrum? You could use (nichicon fg, mundorfs, vs panasonic fc and fr, and large tantallums)

:scratch1:
 
3

31697B

Disabled Account
Joined 2012
Are we talking long lead times for the P-N compl MOSFET type in one package? I got those (ALF08NP16V5) from Farnell/UK in one week to California-USA. Others should be same time if in stock. Maybe you just ordered too many. For 10 pieces or a few more, it is no problem.


Thx-RNmarsh
 
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Lazy Cat

Lazy Cat

Member
Joined 2007
hose4 said:
Dear Lazy cat!

As you know my Vssa project has been finished few months ago.
My new 1200W power supply is waiting for the new Xmas present.
I can hardly wait for the new boards and box.

BTW nice measurements. Did you try with different feedback caps? Would be nice too see if there is a change in spectrum? You could use (nichicon fg, mundorfs, vs panasonic fc and fr, and large tantallums)

:scratch1:
Click to expand...

Hi :wave2:

Last details to sort out before releasing the series has to be done.

Regarding capacitors, I Will probably test with only one different brandname just to see and evaluate the amount of measured difference caused by changing the caps. I think the pattern will emerge quite clearly. ;)
 
Lazy Cat

Lazy Cat

Member
Joined 2007
danny_66 said:
Hi Andrej,
Nice declining distortion spectra of the First One !
I'm looking forward to it.
There's a new version of ARTA to play with. :)
Besides ARTA I've also used REW5 with my speakers, it seems that you can also use REW5 for amplifier measurements.
Regards,
Danny
Click to expand...

Hi danny_66 :wave:

Yes realy nice monotonic declining harmonic spectrum I got from the First One. Will check out the spectrum also with lower power levels ie. 1 W and 10 W, because input sine signal from the card is much clearer then.

For now ARTA is sufficient for my work showing me all the data I need, will do upgrading soon.

Thanks for the tips. :cheers:
 
vgeorge

vgeorge

Member
Joined 2004
goldenview.gr
Lazy Cat said:
Very nice finish vgeorge. :up:

Any problem with GND loops, hum etc.?

Speakers will be ...

What other amps you have to compare to?

Regards, L.C. :cheers:
Click to expand...

No problems with hum or ground loops. Completely silent.
Speakers are horns around 100dB. Have a look here : http://www.diyaudio.com/forums/multi-way/186540-my-island-speakers.html
I have Aleph J, Baby Huey (el84 pp from another thread here) and Sonny' s TSSA running in class A with dual SMPS.
This one and Sonny' s are my favorites do far. TSSA maybe a tad sweeter on the top, VSSA a little more dynamic. Differences depend on taste and mood mostly. I love both of them so far.
One note though, I prefer both of them without the bypass feedback capacitors.
 
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