Friend of mine try to listen my new amp. He comment that my VSSA variant. has more "airy" 🙁. May be my new amp do not have enough slew rate? I will try simple VAS for my 3EF.
Hello uncle Os, i try simulate wolverine.asc, it clip on negatif rail only (look like sticky)
Spookyamp have more good clipping behaviour.
Spookyamp have more good clipping behaviour.
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Airy and fast is exactly how I would categorize CFA topology amps. TSSA V1.6 was very impressive, offering possiblity of class A bias. The 1.7 apparently improves upon its predecessor. One issue I has with this amp and seems to fall in line with the more complex topologies I have listened to is a loss of body and tone. Perhaps this is the seductive 2nd harmonic bloom, but i dont think so, as many of the PP Class A amps I have listened to still have it but will show lower 2nd to 3rd.
yup , weny back to the diode clip clamp. Check the 2sc3503 model , even
with the transistor clamp , all the other models work except these.
Maybe other KSAxxxx should be tried.
OS
Can you show IPS schematic of TSSA V1.6? May be we can modify it using this 3EF OPS.
I found the schematic. It is not simple 😱. Too many transistors. The VAS is driving the load 😱. May be I can sim VSSA input using CFP like this 😕
I agree, but that was the point. In general, I find there is a tradeoff in building. Every time you add something, you lose something. Where that line is is not simple and I do not believe simple is the answer.
Back to the diode ...
Yes ! The diode is both simpler and makes for a better clamp.
I think the transistor clamp is dependent on how fast it is ... or
how fast it can clamp as compared to how fast the main VAS can
saturate.
Basically , a Cob vs. Cob / Ft vs. Ft "war" between the clamp/VAS.
A fast diode is many magnitudes speedier than the compensated VAS.
Much nicer clipping behavior with the simple solution (below 2).
The downside is now I have 6ppm 😱 😱 THD .... boo hoo !
Slight reverse diode leakage "steals my ppm's" ... 😀
Main CCS saturation (3'rd attachment) is way better with 2 references.
Updated Wolverine - tested SW and gross overload (2.8V input) - GOOD !
As compared to the "badger" ... 1/2 the THD20 ( dadods cascode !! 🙂 ) ,
slew is over 100v/us (70 - badger) UG is higher 1.1mhz.
At 120v p-p - just 15ppm 20K - one "bad amp" hooked to the "monster" 5p EF3.
PS - tried 2-3 different models at each stage , perf. remains the same ... performance
is not model dependent ... but design dependent.
OS
Yes ! The diode is both simpler and makes for a better clamp.
I think the transistor clamp is dependent on how fast it is ... or
how fast it can clamp as compared to how fast the main VAS can
saturate.
Basically , a Cob vs. Cob / Ft vs. Ft "war" between the clamp/VAS.
A fast diode is many magnitudes speedier than the compensated VAS.
Much nicer clipping behavior with the simple solution (below 2).
The downside is now I have 6ppm 😱 😱 THD .... boo hoo !
Slight reverse diode leakage "steals my ppm's" ... 😀
Main CCS saturation (3'rd attachment) is way better with 2 references.
Updated Wolverine - tested SW and gross overload (2.8V input) - GOOD !
As compared to the "badger" ... 1/2 the THD20 ( dadods cascode !! 🙂 ) ,
slew is over 100v/us (70 - badger) UG is higher 1.1mhz.
At 120v p-p - just 15ppm 20K - one "bad amp" hooked to the "monster" 5p EF3.
PS - tried 2-3 different models at each stage , perf. remains the same ... performance
is not model dependent ... but design dependent.
OS
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The technical differences between this and the Badger seem 'academic' - is there any difference in the sound ?
It is badger like.
The differences are -
1. LTP CCS and VAS CCS are not "bridged" from the same V reference.
This is a "clipping" thing. When the VAS saturates it takes the big
CCS "with it". This draws more current from the reference. On the badger
this also affects the LTP CCS.
On the "wolverine" , I increased current available to the main CCS +
its totally separate. MUCH better overload behavior.
2.Dadod's Cascode - halves THD20 , has no ground reference ...
totally in the signal path. This is also a "magic thing" - the sound
is much better ( as described by a "GURU" - 2 of them 😀 ).
ps- this might be a BIG one.
3-More aggressive TMC , EF3 compatable , cap multipliers or boosted rail.
4. Way better layout - floating NFB.
This should have no match .. blameless wise. Seen ASTX's EF2 blameless with
modular dongle do 9 ppm despite it all . No dongles here !
OS
Ostripper,
Those are hand layouts! No computer help at all? That sure doesn't look like a tape layout to me, way to nice.
Those are hand layouts! No computer help at all? That sure doesn't look like a tape layout to me, way to nice.
No , it's a hybrid. Sprint (computer) lets me drop pads , but to go from schema
to actual layout - no assist.
I had eagle , but it does not know about Hi-Z/lo-Z or what section is
VAS/cascode/CCS - does auto routing. I like "hands on". 🙂
OS