76.2 X 76.2mm ... not small enough ? 3" is tiny !
I know many like SMD , but where would I get that 220u NP cap (SMD ?)
PS - the front of the case is also a option , leaving the rear for AC/in-out.
OS
With SMD ... I could most likely do all the resistors , small PS decoupling.
VAS main devices , silver mica's , and that dang big electro would
remain through-hole.
Maybe <50mm X 76.2mm would be the net result.
(below) is the 76.2 X 76.2mm pcb.... just a little larger than a credit
card ... printed it out , fits in the palm of my hand.
Any case worth its salt that could accommodate these large amps
would have 10-15" interior width (250-375mm).
This would leave 4 -8" extra as 2 IPS's would use 150mm. Front
panel mounting would also be a option.
Most do not have SMD soldering equiptment ... for a commercial
venture .. I WOULD go for at least a partial surface/through-hole
endeavor.
OS
Attachments
Today i have trim these resistors R16,R13 to take the recommended VAS current 7,1mA-8mA.
So new values for R16,R13 are 560R.
With this value(R16=560R) Vr21=1.1V SO I VAS=V/R=1.1V/150R=7.33mA.
I have change value of R18 also.
New value for R18=22k so Vr18=79,2V I=V/R=79,22/22.000=3,6mA.
I have a small test on digital oscilloscope also,and ONLY a burned 10R .
Zobel network.
I have an alternative IN board in stand-by.
Thimios.
So new values for R16,R13 are 560R.
With this value(R16=560R) Vr21=1.1V SO I VAS=V/R=1.1V/150R=7.33mA.
I have change value of R18 also.
New value for R18=22k so Vr18=79,2V I=V/R=79,22/22.000=3,6mA.
I have a small test on digital oscilloscope also,and ONLY a burned 10R .
Zobel network.
I have an alternative IN board in stand-by.
Thimios.
Attachments
I think those old ones use the same V+/- PD+/ND- and ground scheme.
These are set up for EF3 ... lower VAS I. Run em' hot (7-8ma) and
your old EF2 would also "sing" !
PS- NFB would also have to wired - it's separate now.
OS
Today i have trim these resistors R16,R13 to take the recommended VAS current 7,1mA-8mA.
So new values for R16,R13 are 560R.
With this value(R16=560R) Vr21=1.1V SO I VAS=V/R=1.1V/150R=7.33mA.
I have change value of R18 also.
New value for R18=22k so Vr18=79,2V I=V/R=79,22/22.000=3,6mA.
I have a small test on digital oscilloscope also,and ONLY a burned 10R .
Zobel network.
I have an alternative IN board in stand-by.
Thimios.
Is the last pix (CFA-X) vssa ?? Next one ...
OS
You ask me?
Is the last pix (CFA-X) vssa ?? Next one ...
OS
Ha ha ha i am confused a little ...
I will try to find schematic for this but i haven't any non polarized capacitor
Two capacitors back to back ? may be....
Thimios.
Last edited:
this is my progress of so far... I have some questions about CFA-X
1)Capacitors C5-C6 must be nonpolar?can we use single polarity electrolytic caps?
2)what alternatives can we use instead of ksa992-ksc1845?
3)do transistors Q1 and Q2 have to be matched ?
1)Capacitors C5-C6 must be nonpolar?can we use single polarity electrolytic caps?
2)what alternatives can we use instead of ksa992-ksc1845?
3)do transistors Q1 and Q2 have to be matched ?
Attachments
1)use 2x2200 back to back for each of this.
2) 2sa 970 or 2sa1015-2sc1845 or 2sc1815
3)yes.
Good luck.
Last edited:
Nice work thimios.
Hopefully we will have a few different versions soon with listening test so we can stop the Madness of new versions every day! I have no idea what country you are in but you do some nice work and seem to be almost as fast making working models as OS is at creating new versions and updates.
Perhaps we can settle on a few versions soon and have some group buys of boards from someone on each of the continents.
Hopefully we will have a few different versions soon with listening test so we can stop the Madness of new versions every day! I have no idea what country you are in but you do some nice work and seem to be almost as fast making working models as OS is at creating new versions and updates.
Perhaps we can settle on a few versions soon and have some group buys of boards from someone on each of the continents.
Thank Kindhornman, i live in Greece.
O dear just now i see that you are an Waveguide & loudspeaker designer!
My congratulations.
Thimios.
Last edited:
Oh , give me a break ...
HERE is the goal.
-All my previous VFA designs. - almost done (Wolverine -SYMASUI )
-A new VFA (the spooky leach) ... never designed one.
-The 2 new CFA's (NAD /CFA-X)
-successfully using the hawksford with a EF3 ... did this before ,
but on a EF2 .. "ran out of gas" under load.
After the "symasui" , only one more topology left ...{the folded
CASCODE}.
With these 6 IPS's we will cover just about all the major class AB
input stage/VAS combinations.
Everyone should be able to find some "magic sound" in one of them.
You get sick of one "magic" , choose another without redrilling/major
rework -waste.
DIY'ers like to "tinker" (I do !
) , this setup facilitates this.PS - I've seen other threads go for month's ---> year before they get refined performance.
Some still have issues long after the group buys/prototypes. NOT here !!
OS
Last edited:
Agree Agree Agree!Oh , give me a break ...
HERE is the goal.
-All my previous VFA designs. - almost done (Wolverine -SYMASUI )
-A new VFA (the spooky leach) ... never designed one.
-The 2 new CFA's (NAD /CFA-X)
-successfully using the hawksford with a EF3 ... did this before ,
but on a EF2 .. "ran out of gas" under load.
After the "symasui" , only one more topology left ...{the folded
CASCODE}.
With these 6 IPS's we will cover just about all the major class AB
input stage/VAS combinations.
Everyone should be able to find some "magic sound" in one of them.
You get sick of one "magic" , choose another without redrilling/major
rework -waste.
DIY'ers like to "tinker" (I do !
PS - I've seen other threads go for month's ---> year before they get refined performance.
Some still have issues long after the group buys/prototypes. NOT here !!
OS
I have listen this amplifier a little but i come for 2nd channel instantly!
Congratulations OS.
Thimios.
