FET-hex explendit amplifier
- Thread starter borys
- Start date
Also Same thing for the 22k input resistor gnd for separation from 100uf gnd trace.
Fab
In addition, If you intend to follow Lazycat published amplifier ground connections scheme for its VsSA you may consider adding more terminals for GND connection on pcb ( for main central gnd of amplifier thus for main power supply caps gnd, zobel, speaker return gnd, etc...) or
you may prefer your main amp central gnd closer to the main power supply gnd.
I do not know if there is an accepted preferred gnd scheme be between 2 above options...
Fab
you may prefer your main amp central gnd closer to the main power supply gnd.
I do not know if there is an accepted preferred gnd scheme be between 2 above options...
Fab
No fab with one GND faston spad i achieve all ground necessary ground connections : speaker, chassis, PSU (see the picture how i manage LC recommandations)
For supply spad i don't want them too near signal board connection...In the better case i desire GND/+V/-V connection near output section but i want apply that here i need to grown up board length...i didn't want that
Marc
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I am just thinking about universal board (just few resistor values differend), board for BJT can take o/p transistors:
-BJT
-IRFP
-2SJ/2SK
The only difference for mosfets would be another driver pair (required for BJT outputs). I have asked few posts before about adding another pair of drivers for mosfets (so we will have 8 transistors in direct signal line) - but had no response.
I will test that on wednesday (will have some time), have some 2sj201/2sk1530 in stock so why not try them on.
Idefixes
Have you got link adress for that psu board ?
-BJT
-IRFP
-2SJ/2SK
The only difference for mosfets would be another driver pair (required for BJT outputs). I have asked few posts before about adding another pair of drivers for mosfets (so we will have 8 transistors in direct signal line) - but had no response.
I will test that on wednesday (will have some time), have some 2sj201/2sk1530 in stock so why not try them on.
Idefixes
Have you got link adress for that psu board ?
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Funny i was thinking at somethink quite near but a little different :
=>Input board+Output board (Mosfet or BJT or Latfet)
For PSU => capacitance multiplier
Marc
BJT's,irfp, 2sk/2sj (toshiba) they have same pinout so there is nothink to modify to fitt them. Latfets they have different pinout - so different board.
THX for psu link.
For Mosfets you don't need drivers, and for Lateral mosfets, you also don't need bias servo. But drivers with Mosfets (both lateral and Hex fet) will double the slew rate. They will just make amp better, so if there is place on pcb you can use them with any of the output transistors: BJT, Hexfet or Latfet. But you must test the stability of the amp if drivers are used.
I have to do test either, before spending money in BG1-3BJT i think i will swap on BG1-BJT from Sanken to MJL3281/1302 to see if there is any change in sound caracteristics...
Marc
Marc
your input stage ground layout is a lot better
I really consider using your layout now...😎
Fab
Just tu confirm, BG1 is working with fets OK. I have soldered 2sj201/2sk1530, replaced gate resistors with 100R and putted two zeners. Bias is setting up ok. At the moment I have as bias transistor bd139 and cold amp setted up to 45mA bias is dropping to 38mA after 10min playing of music (so is not too bad).
Idefixes
If you will made a room just for two zeners on the board there would be posibility to solder BJT or mosfets at output.
Sound with toshiba mosfets has really rich top end, worth every penny I have spent on them.
Idefixes
If you will made a room just for two zeners on the board there would be posibility to solder BJT or mosfets at output.
Sound with toshiba mosfets has really rich top end, worth every penny I have spent on them.
Attachments
Borys could you pointed me on schematic?
Marc
Marc
I will do that evening time, now I am ''at work''.