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VSSA Lateral MosFet Amplifier

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Lazy Cat

Lazy Cat

Member
Joined 2007
Lazy Cat

Lazy Cat

Member
Joined 2007
BYRTT said:
Played with simulation of GB circuit (copyrighted so please don't ask schematic other than Andrej). Implemented Esperado schematic from post #2629 the best my hobbist skills allow, remember it's simulation only. The audio band group delay gets perfect linear when zoomed into nano seconds. Christope i am in doubt about truth for 20Hz square, could result be right ?
Click to expand...

Yes OK, that was also the case in SSA amp without FB caps. Now please simulate thermal behaviour in VSSA especially input stage, if caps are removed. :rolleyes:
 
Esperado

Esperado

Member
Joined 2011
esperado.fr
Lazy Cat said:
Yes OK, that was also the case in SSA amp without FB caps. Now please simulate thermal behaviour in VSSA especially input stage, if caps are removed. :rolleyes:
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Well. If there is, as i fear, too much rock'n roll for the Andrej Sisters ( Andrews Sisters' "Boogie Woogie Bugle Boy of Company B". [VIDEO]), we could think about some servo ?
Let list some advantages:
1- It is less expensive than big lytics and lot smaller.
2- As we don't have residual signal at HF, we should use some high value ceramic SMD caps for the FC without resonance's fears.
3- The FC can be very low, with little impact on HF distortion and group delay for (BYRTT ;-), and huge improvement on BF distortion.
4- No need for offset adjustment's networks and their multi turns.
The cons are:
1- (little) added noise.
2- Complexity (specially rails reducing voltages circuitry).
3- The price of a nice bottle to Richard Marsh ?
 
BYRTT

BYRTT

Member
Joined 2009
Lazy Cat said:
Yes OK, that was also the case in SSA amp without FB caps. Now please simulate thermal behaviour in VSSA especially input stage, if caps are removed. :rolleyes:
Click to expand...

:rolleyes: Yes Andrej i am a SPEC dreamer without skills to see drawbacks :).
But another thing about feedback cap influence. Is it possible to make group delay opposit in lows without ruin FR as a curve for repairing speaker driver+cabinet highpass function, as been possible nowadays in digital domain by FIR filters. I ask this because that cap position control AC swing by amp, and maybe a clever circuit could make that function.
 
maxlorenz

maxlorenz

Member
Joined 2003
youtube.com/channel/UCIRNCQpvrl-EfalifsmR4KA
Originally Posted by BYRTT View Post More spy info see picture from "First One" prestage. If it's SMD-film said:
:D Replaced with Vishay film cap, just as in VSSA. All parts individualy tested for new First One amp, priority is of course sound quality. Right now first new First One PCB is in assembly process. :cool:
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What about 2m2F//10uF SMD//small film caps, like 0n3F to 1uF?
Where do you guys source your Vishay's? :mad:

Will try to post pictures of my humble effort for the true VSSA soon.

Cheers,
M.
 
BYRTT

BYRTT

Member
Joined 2009
maxlorenz said:
..........Where do you guys source your Vishay's? :mad:..........
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A try, the first i bought myself (WIMA) and fits 100% and at same it's Mouser Chile link, last four links to Farnell (Element14) Denmark then change countrysite and see if it works, good surfing.

C4.PNG MKS4B051004J00KSSD WIMA | Mouser
C3.PNG MKT1820610065 - VISHAY ROEDERSTEIN - CAP, FILM, 10UF, 10%, 63V, RADIAL | Farnell Danmark
C5.PNG B32562J1106K - EPCOS - CAPACITOR, 10UF, 100V | Farnell Danmark
C1.PNG B32522C106K - EPCOS - CAPACITOR POLY FILM 10UF 63V 10 | Farnell Danmark
C2.PNG B32523Q106K - EPCOS - CAPACITOR, 10UF, 63V | Farnell Danmark
 
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Esperado

Esperado

Member
Joined 2011
esperado.fr
analog_sa said:
I see a good probability to destroy the sound chasing after a non-existent problem. Good luck.
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Sorry, but, unless you introduce some kind of compensation, more you have gain, more you have offset problems.
AS used by L.C., the caps are here to reduce the gain of the input stage at DC,
The problem is they *pass* the signal in the audio band, at relatively low impedance, so, need to be high µF.
If you design accurately a servo, it will not introduce distortion in the audio band, as it will produce no signal except at very low frequencies.
A servo *add* feedback at very low frequencies. The L.C. cap reduce the gain of the input stage.
As the IC used for servoing can be very high input impedance, we can use low values caps, film ones, that's the advantage.
 
BYRTT

BYRTT

Member
Joined 2009
Ranchu32 said:
Hi guys, I forgot to fit the spacers before installing the VAS transistors and had to cut them out to des older without ruining the boards. Does anyone know where I can find replacements?
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Lazy Cat said:
Fairchild's KSA/KSC are stocked by Mouser. ;)

Please follow Installation manual step by step. ;)
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Idefixes said:
Yes LC but already E range for 1381 and D range for 3503:(:(:(

Marc
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Hi send a PM to PMI and tell you have LC's GB PCB's and the situation, then i think his good heart will help you.
Link PMI profile: diyAudio - View Profile: PMI
Link PMI throug hole VSSA: http://www.diyaudio.com/forums/soli...hrough-hole-pcb-build-thread.html#post3682318
 
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