Version VSSA 1.4 is no doubt the De-Luxe version.
Anybody who likes to try should go for this: http://www.diyaudio.com/forums/solid-state/225747-vssa-lateral-mosfet-amplifier-7.html
Anybody who likes to try should go for this: http://www.diyaudio.com/forums/solid-state/225747-vssa-lateral-mosfet-amplifier-7.html
Hi LC,
The major issu for common Diyboy with you puppie will be the resistors tunning as it handel to solder CMS with those electrolytics and 10µ so near...That's why i don't know if just after TSSA BIGBT HP il will go for your neat vssa or i go for my layout. The board is bigger (73*63mm) but tricky resistors are on solder side. I have pad to solder tunning trimmer that will be removed. According to V1.4 VAS are on main heatsink and TLVH431 is present.
Marc
The major issu for common Diyboy with you puppie will be the resistors tunning as it handel to solder CMS with those electrolytics and 10µ so near...That's why i don't know if just after TSSA BIGBT HP il will go for your neat vssa or i go for my layout. The board is bigger (73*63mm) but tricky resistors are on solder side. I have pad to solder tunning trimmer that will be removed. According to V1.4 VAS are on main heatsink and TLVH431 is present.
Marc
Attachments
L.C, as i previously noticed, your SSA link does not work (some people use to read the forum last message first) . This link would be better, i suppose:
http://www.diyaudio.com/forums/solid-state/225747-vssa-lateral-mosfet-amplifier-17.html#post3298495:
http://www.diyaudio.com/forums/solid-state/225747-vssa-lateral-mosfet-amplifier-17.html#post3298495:
Any chance to use N-Channel Only?
Hello Andrej, great job, well done!
For a couple of years I have been looking for a simple current feedback topology with high BW and SR, and now I finally find it here. What is more, from your threads, I see a good heart as well as a very knowledgeble mind. This is truly something that I respect.
By the way, your English is perfect to me!
There is no question I will build this amp.
However, I have one question: is there any chance to use N-Channel only for the o/p? I have 200+ more IRF530s and some 2SK312/512s. But no 2SJ. And the ALF08NP is not obtainable to me. Also, I think it is not inexpensive at all to use K1058/J162 with your VSSA.
That aside, your topology is almost perfect for DIY.
Thank you very much for bringing such a good design to the DIY community!
Hello Andrej, great job, well done!
For a couple of years I have been looking for a simple current feedback topology with high BW and SR, and now I finally find it here. What is more, from your threads, I see a good heart as well as a very knowledgeble mind. This is truly something that I respect.
By the way, your English is perfect to me!There is no question I will build this amp.
However, I have one question: is there any chance to use N-Channel only for the o/p? I have 200+ more IRF530s and some 2SK312/512s. But no 2SJ. And the ALF08NP is not obtainable to me. Also, I think it is not inexpensive at all to use K1058/J162 with your VSSA. That aside, your topology is almost perfect for DIY. Thank you very much for bringing such a good design to the DIY community!
Hi MKHunt
OK, VSSA will finally go into PCB and semiconductors as kit soon enough, will certainly make an announcement here.
Your source and tube pream seems good match for the purpose.
OK, sure to be informed about GB.
Yes the design is just perfect for DIY, low BOM count, small, very versatile, immensely stable in both DC and AC respect and sounds gorgeus.
By default bias level 0,4 Wrms at 8 ohm, with good heatsink provided, bias can be trimmed to enable 1 Wrms/8 ohm class A without any problem.
how cricital is CCS symetry and exact value ? , I would think to use j508/j509 current diodes , but tolerances of those are not good , 20% ,
CRD-s are untrimmable and it would be almost impossible to balance DC offset and to set correct input/VAS bias current even with large asortiman. So the solution with j-fet and two fixed resistors is just optimal as enables trimming to +/- 5 mV output DC offset and VAS bias to cold start level of 12 mA. What's best it is time wear-proof since there's no trimmer present after initial calibration.
Something that would work is to get one BF245A JFET (or BF245B) for each current source.CRD-s are untrimmable and it would be almost impossible to balance DC offset and to set correct input/VAS bias current even with large asortiman. So the solution with j-fet and two fixed resistors is just optimal as enables trimming to +/- 5 mV output DC offset and VAS bias to cold start level of 12 mA. What's best it is time wear-proof since there's no trimmer present after initial calibration.
These BF245 Jfets are easily found most everywhere.
So they are easy to buy.
Hello Andrej, great job, well done!
For a couple of years I have been looking for a simple current feedback topology with high BW and SR, and now I finally find it here. What is more, from your threads, I see a good heart as well as a very knowledgeble mind. This is truly something that I respect.
There is no question I will build this amp.
Thank you very much for bringing such a good design to the DIY community!
Thank you jazzclassics for very kind and gentle words.
Well, only N-channel and also vertical mosfets I didn't consider to fit into my fully symmetrical type of amps. I don't imply that's not possible, but there we would also ran into thermal stability issue with verticals as that would take some extra parts to make it thermally stable.
Also I think ALF08NP is unique transistor on the market as just made for the purpose in VSSA and also we all can be pretty sure it is genuine when bought. Also to my humble opinion it is one level better performer than 2SK/2SJ.
Any type of N or P ch j-fet providing Id=8 mA at Vgs=0 V is OK, so when calibrated to cca. 2,4 mA as CCS in VSSA, Rgs at that point (two parallel fixed setting resistors) is in a range of 1 kohm.
The only limiting factor is Vds max, which at 2N5462 is 40 V. Solution is to put resistor in series with CCS to take few extra volts. I can consider this and implement BF245B plus serial resistor in a GB PCB since this one is easily obtainable.
After coming back home I cannot stop listening to my lab test setup composed from nothing but PCB-s only. It is best PCB system at the moment for sure. HD tracks are alive like performed by ABC network player. 
Regards Andrej
Regards Andrej
Attachments
Any type of N or P ch j-fet providing Id=8 mA at Vgs=0 V is OK, so when calibrated to cca. 2,4 mA as CCS in VSSA, Rgs at that point (two parallel fixed setting resistors) is in a range of 1 kohm.
The only limiting factor is Vds max, which at 2N5462 is 40 V. Solution is to put resistor in series with CCS to take few extra volts. I can consider this and implement BF245B plus serial resistor in a GB PCB since this one is easily obtainable.
2sk246/ 2sj103 BL grade ,
but why it has to be Idds 8mA ??