Very simple quasi complimentary MOSFET amplifier

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#1,962
Vrystaat said:
Prasi, If we use your circuit then we don't need to populate the resistor and cap of the zobel on the main pcb.
Click to expand...

AndrewT is asking to populate zobel at both places,

AndrewT said:
The advantage of adopting the Thiele version 2 network is that when a Version 1 Zobel is on the amp PCB, this Prasi addition at the speaker terminals gives a Pi version of the Thiele Network. This is part of what Jon was referring to.
It is what I have been using for a few years.
It gives good HF performance to the benefit of the amplifier and it gives extra attenuation of interference coming in from the long aerials we call speaker cables.
This speaker cable interference is injected into the -IN node of the amplifier
Some amplifiers actually add a capacitor across the upper feedback resistor to allow direct injection of interference into the -IN node.
Click to expand...
 
#1,964
touchdown said:
@DACZ,

while l dedicate myself to the building of Cubie3 amp, my nephew would like to build this VSQCM amp making use of the (gorgeous) double sided boards that you preseted in the #1915 message.
Opening the gerber files, we noticed that:
1. both top and bottom soldermask files leave out one of the two holes made for the "+42V" power connector (female faston);
2. the "smdmask_bottom" file, which includes the mask only of 3 SMD capacitors, is a separate file from the "soldermask_bottom" file; could you explain us how we can correctly send it to the PCB fab? I/we are not expert about PCB design...

Could you kindly verify and advice us about these issues?

Many thanks
Nicola
Click to expand...

Yes Nicola, the faston hole is missing. same question from my friend.. i recompile the gerber.. pls let me know any other issue to correct it. the smd file is there if you have a 100n smd. if you can notice there are two C11.. one smd and one through hole.. u need only to fix smd parts or the through hole parts, not both.. same as C13. the other smd pad is J1 below D10. Solder it if you don't use D9 and D10. See the schematic.

regards,
Dacz
 

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  • VSQCMosfetSchem.JPG
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#1,968
Dacz,
many thanks for the revised version and for your clarifications about smd file; all is clear now!
We couldn't see any flaws and my nephew is going to send it to a PCB fab. He's preparing all components to assembly a complete amp in the next months.

Great!
Nicola
 
#1,970
Kay Pirinha said:
Where did he ask this? And why? Most probably two Boucherot's (one before and one after the output inductor) won't harm, but I also don't recognize any benefit from the second one.


Best regards!
Click to expand...

I understand Andrew's reasoning and have tried this arrangement myself in at least two of my amplifiers however its not something to obsess over.

What is important is that a zobel is present on the main pcb close to the output devices. The coil can be placed either on the this same board, inline the wiring to the speaker terminal, or on a small auxiliary pcb near the speaker terminals. A secondary zobel immediately at the speaker terminals to chassis ground can be beneficial to prevent RF ingress from the speaker cable inside the enclosure however the benefits are questionable IMHO.
 
#1,971
Vrystaat said:
Thiago, can you plse give me the flipped side of the pcb layout.( Inverted)🙂
Regards


Here it is.... flipped (mirrored) pdf of the PCB as viewed from component side.🙂
Click to expand...
 

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