FET-hex explendit amplifier

First channel BG1-bjt Sanken is running...Picture under : Left BG1_bjt Sanken / Right : LC-VSSA....So go to mount second chanel BG1-bjt
 

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So i'am in love for the second time in one week....
Clearly it's the same family as VSSA LC...a little less bright as mosfet one but what a strongness in the lower frequency. These version seems more aware with my speakers as the Latfet one. For the rest LC-VSSA and BG1-bjt have same profile on details, sound stage, dynamic, ... BG1_bjt is quite sound dead as VSSA. I apply same wiring configuration as LC indicate...that's for sure the way to go. Thanks LC for sharing on VSSA and Borys for iteration and sharing on BG1-bjt.
 
Thank you Idefixes !
Good to read you happy with the result. I hope you can enjoy your speakers and don't need to swap those pricy woofers
A big thank you to BORYS to!

Greetings Gabor

Gabor...the fact is that i have in stock Fountek JP3/Cquenz 15h52sdkm/peerless HDS205 nomex and crossover parts.....For Sure a big thank to Borys and LC...there's really something magic in VSSA line.

Marc
 
what settings you have done?

I have +/-35Vdc rail and apply what borys indicate :

1. Set 1k trimer at max value, set offset trimmer to get 330R all together with 680R resistor (they are parallel)
2. Power up the amp with +/-35V (or similar voltage), you can use 10R-22R/5W resistors in rails for first run and setup
3. Set up offset at first close to zero.
4. Set up bias trimmer to get around 22mV across 0,22R emiter resistors = 100mA
5. Check and correct offset trimmer again.

Offset may drifft a bit when cold/hot, so for example:

If offset is rising when heating up, set it cold aprox -5 -10mV and when heating up it will go to 0 or +5mV.

BC550C/560C are N/P matched, BC556B are matched, BC546B are matched, KSA1381/KSA3503 are n/p choose close as possible (Hfe 169 and 180). For BC i had stock from previous project so i used them...Offset is close to and easy to set.

Marc
 
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A let amp more than half an hour on workbench and today is hot day (37°C at shadow) and i see nothing special.

I just listen Diana Krall "live in Paris" album...A real pleasure time. I can listen witout push the amp and at low power level all is clean and detailed. The live background is here with all details and background.

Marc
 
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For one who want to give a try to BG1_BJT_sanken (but the layout is ok for TO264 BJT too) For setting look post#190

Print Bottom pdf file without scaling. The board size is : 87,3x89,8mm

Marc
 

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Thanks to all

I am looking forward to see more amps in this tread.
You can try irfp version too - it hass very good bass.
I have made DF measurement and it was 730!! real DF for 8R@100Hz (without source resistors).

Bellow (not testet yet) BJT version for 1,2,3,4 output pairs. You can cut as many transistors as you want and fitt or not capacitors next to them.

Regards
 

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