FET-hex explendit amplifier

Samuel Jayaraj · 2013-08-02 9:24 pm

Bias down to 26mA for output transistors alone and see how it goes!!

Idefixes · 2013-08-02 10:10 pm

Samuel Jayaraj said:
Bias down to 26mA for output transistors alone and see how it goes!!

Will test next time amp sit on bench... Thanks.

Marc

borys · 2013-08-02 10:13 pm

I seted bias by mistake at 10mA per BJT o/p transistor and did measurement - and it was same as with 100mA bias. Soundwise I do not know what would be the diffrence.
So BJT do not need high bias anyway to run properly.

Idefixes · 2013-08-02 10:28 pm

borys said:
I seted bias by mistake at 10mA per BJT o/p transistor and did measurement - and it was same as with 100mA bias. Soundwise I do not know what would be the diffrence.
So BJT do not need high bias anyway to run properly.

Borys could you do the test on your BG1-BJT and tell us if you seen sound modifications?

Marc

Idefixes · 2013-08-03 9:27 pm

During music listening session i spend a little time with eagle to give a face to +/-50V 2BJT version...see attached. There is 2 versions : one with To264 devices (MJL) and one with TO3P (NJW)

Marc

alex mm · 2013-08-03 10:25 pm

..... very nice PCB's, congrats Mark , will be my next project .....

borys · 2013-08-03 10:40 pm

Idefixes said:
Borys could you do the test on your BG1-BJT and tell us if you seen sound modifications?

Marc

I will try to spend some time this week, currently I was working on some smaller simpler amp but it is finished up so will have some spare hrs.

Regards

Idefixes · 2013-08-03 10:55 pm

alex mm said:
..... very nice PCB's, congrats Mark , will be my next project .....

Mine will be more 3BJT version as i have good stock matched MJL3281/1302....Board size is 150x86mm

Lazy Cat · 2013-08-03 11:35 pm

That was exactly the intention from the very beginning, strong competition between all kinds of VSSA iterations, no room left for blameless ideas. :cheers:

Jay · 2013-08-04 12:20 am

Lazy Cat said:
That was exactly the intention from the very beginning, strong competition between all kinds of VSSA iterations, no room left for blameless ideas.

Hehe im still wondering why the complex honey badger could get into the sticky. Two of them. It should be good but too complex for me.

ivanlukic · 2013-08-04 5:14 am

Idefixes said:
Mine will be more 3BJT version as i have good stock matched MJL3281/1302....Board size is 150x86mm

This one will "Rock the Casba"!

naf · 2013-08-04 7:26 am

Idefixes said:
During music listening session i spend a little time with eagle to give a face to +/-50V 2BJT version...see attached. There is 2 versions : one with To264 devices (MJL) and one with TO3P (NJW)

Marc

very nice layout Marc, what is dimensoin?
i'll prepare to listen bjt version

Idefixes · 2013-08-04 8:46 am

naf said:
very nice layout Marc, what is dimensoin?
i'll prepare to listen bjt version

TO3P : 120x87mm
TO264: 125x87mm

Since there is only is only 5mm difference between the two board better is to go for TO264 one more versatile beacause comptable with TO264 and TO3P

Marc

Idefixes · 2013-08-04 1:23 pm

ivanlukic said:
This one will "Rock the Casba"!

To "Rock the Casba"

:

jorgovanko · 2013-08-04 3:54 pm

Idefixes, maybe is not bad to change the following things on the PCB:

An externally hosted image should be here but it was not working when we last tested it.

This is what I have noticed at first glance. Maybe there is still room for improvement.

edit: Also, 22K resistor (part of CCS) should go to GND, not to GND1?

BR,
Boban

fab · 2013-08-04 4:06 pm

Coupling cap ground

Idefixes said:
During music listening session i spend a little time with eagle to give a face to +/-50V 2BJT version...see attached. There is 2 versions : one with To264 devices (MJL) and one with TO3P (NJW)

Marc

Nice layout Marc. However, I wonder if the 100uf power supply caps ground should be better connected to GND than GND1? Or connect to GND1 before meeting 2200uf feedback caps gnd trace connection? Like a star connection for parts that connect to GND1.

Thanks

Fab

Idefixes · 2013-08-04 4:08 pm

Hi boban, i though to this configuration but this configuration let a bit room to plug signal connector(room due resistor). With you mod. signal connector is direct to 4u7 and his boring...my finger are not really thin...Idem for cap : when ripping to install cap. trimmer is direct near faston plug so not confortable to adjust bias....

Marc

Idefixes · 2013-08-04 4:18 pm

fab said:
Nice layout Marc. However, I wonder if the 100uf power supply caps ground should be better connected to GND than GND1? Or connect to GND1 before meeting 2200uf feedback caps gnd trace connection?

Thanks

Fab

In that way?

fab · 2013-08-04 4:23 pm

Idefixes said:
In that way?

Yes you are FAST! but I would even connect the 2200uf caps gnd with a separate track directly to GND1.

Fab

Idefixes · 2013-08-04 4:45 pm

fab said:
Yes you are FAST! but I would even connect the 2200uf caps gnd with a separate track directly to GND1.

Fab

====>

Marc

FET-hex explendit amplifier

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