TSSA - The Simplest Symmetrical Amplifier - Page 42

sonnya · 29th April 2012, 03:09 PM

Good progress Joachim.

When i am done the gerber files, the BOM and the Pick and place data.

The board is made with SMT for the frontend.

I can produce the board with all SMT on them, but with above files i will upload everyone else can also.

Regarding the mosfet drivers. Is there an reliable source for 2SK216 and 2SJ79?? Or should wi install IRF instead???

Lazy Cat · 29th April 2012, 03:36 PM

Hi Sonnya

SMT parts are perfect choice here, since there are a lot small signal BJTs connected between themselves only. Try to make as compact PCB as possible.

There are few suppliers that can provide 2SJ79/2SK216. These are lateral mosfets (transconductance falls with higher temperature) so no problem with thermal runaway, also have integrated gate protection zeners - perfect drivers. Try to find these not IRFs.

I cannot wait to see your PCB

Joachim Gerhard · 29th April 2012, 03:37 PM

I can get them still although i think Renaisas stopped production of this transistors. Exicon makes laterals but not TO220. One solution is to use big ones for the drivers too.

Lazy Cat · 29th April 2012, 03:39 PM

Count me in for 2SJ79/2SK216, if you still can get them.

Joachim Gerhard · 29th April 2012, 03:42 PM

Sure, i use 2SJ77 and 2SK214. They can stand enough voltage. I really whould not like to go to hexfets. I think laterals sound better, especially when you go down the drain.
They are excellent constant current souces.

Joachim Gerhard · 29th April 2012, 03:44 PM

away goes trouble down the drain
LAST NIGHT A D.J. SAVED MY LIFE Lyrics INDEEP

sonnya · 29th April 2012, 04:02 PM

Quote:

Originally Posted by Joachim Gerhard

Sure, i use 2SJ77 and 2SK214. They can stand enough voltage. I really whould not like to go to hexfets. I think laterals sound better, especially when you go down the drain.
They are excellent constant current souces.

Last time the bag size was 500pcs and there also is a minimum buy.

Joachim Gerhard · 29th April 2012, 05:19 PM

For this few amps we will build i have enough, but maybe.....

sonnya · 05:50 PM

Second solution:

Raise frontend current 5x
Gateresistor reduced 5x
Maybe change the feedback network by reducing it 2x.

5mA in the front stage but still only 1mA in the input pair.

This Way the drive impedance for the mosfet is 5x lower. I Think this Will improve the thd performance simelar without the mosfet drivers.

Joachim Gerhard · 29th April 2012, 06:42 PM

Sure, that will work too. Nevertheless i build the version with driver first and then we can compare.

29th April 2012, 05:30 PM	#419
sonnya diyAudio Member Join Date: Oct 2001 Location: Denmark	Second solution: Raise frontend current 5x Gateresistor reduced 5x Maybe change the feedback network by reducing it 2x. 5mA in the front stage but still only 1mA in the input pair. This Way the drive impedance for the mosfet is 5x lower. I Think this Will improve the thd performance simelar without the mosfet drivers. Last edited by sonnya; 29th April 2012 at 05:50 PM.

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29th April 2012, 03:09 PM	#411
sonnya diyAudio Member Join Date: Oct 2001 Location: Denmark	Good progress Joachim. When i am done the gerber files, the BOM and the Pick and place data. The board is made with SMT for the frontend. I can produce the board with all SMT on them, but with above files i will upload everyone else can also. Regarding the mosfet drivers. Is there an reliable source for 2SK216 and 2SJ79?? Or should wi install IRF instead???

29th April 2012, 03:36 PM	#412
Lazy Cat diyAudio Member Join Date: Sep 2007	Hi Sonnya SMT parts are perfect choice here, since there are a lot small signal BJTs connected between themselves only. Try to make as compact PCB as possible. There are few suppliers that can provide 2SJ79/2SK216. These are lateral mosfets (transconductance falls with higher temperature) so no problem with thermal runaway, also have integrated gate protection zeners - perfect drivers. Try to find these not IRFs. I cannot wait to see your PCB

29th April 2012, 03:37 PM	#413
Joachim Gerhard diyAudio Member Join Date: Mar 2009	I can get them still although i think Renaisas stopped production of this transistors. Exicon makes laterals but not TO220. One solution is to use big ones for the drivers too.

29th April 2012, 03:39 PM	#414
Lazy Cat diyAudio Member Join Date: Sep 2007	Count me in for 2SJ79/2SK216, if you still can get them.

29th April 2012, 03:42 PM	#415
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Sure, i use 2SJ77 and 2SK214. They can stand enough voltage. I really whould not like to go to hexfets. I think laterals sound better, especially when you go down the drain. They are excellent constant current souces.

29th April 2012, 03:44 PM	#416
Joachim Gerhard diyAudio Member Join Date: Mar 2009	away goes trouble down the drain LAST NIGHT A D.J. SAVED MY LIFE Lyrics INDEEP

29th April 2012, 05:19 PM	#418
Joachim Gerhard diyAudio Member Join Date: Mar 2009	For this few amps we will build i have enough, but maybe.....

29th April 2012, 06:42 PM	#420
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Sure, that will work too. Nevertheless i build the version with driver first and then we can compare.