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Old 11th August 2011, 07:45 AM   #151
alex mm is offline alex mm  Romania
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Hi sng001,
Thanks , I have second PCB rev.1.1 below .
Alex.
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Old 11th August 2011, 11:04 AM   #152
AndrewT is offline AndrewT  Scotland
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The power rails into the Lat FETs come from the rectifier end of the PSU.
The rectifier must feed the smoothing capacitors and then the capacitors must feed the amplifier.
Doing it your way mixes the charging pulses with the audio current in the shared traces around the rectifier/smoothing. There is a high risk of Buzz getting into the output.
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Old 11th August 2011, 11:44 AM   #153
AKSA is offline AKSA  Australia
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Apart from that, Alex, it is a brilliant, beautifully executed pcb layout....

Cheers,

Hugh
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Old 11th August 2011, 12:35 PM   #154
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I agree, nice compact PCB, but I don't think it is a good idea to have AC cables near Mosfet pins, apart the fact that some of us like to apply all kind of tricks to the power supply, like -ECdesigns-' smooth stepped rectification, "charge transfer supply" or even V regulation...

Good luck and thanks for sharing.
M.
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Old 11th August 2011, 12:52 PM   #155
sng001 is offline sng001  Australia
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Attachment 234829
Quote:
Originally Posted by AndrewT[ATTACH
234829[/ATTACH];2668016]The power rails into the Lat FETs come from the rectifier end of the PSU.
The rectifier must feed the smoothing capacitors and then the capacitors must feed the amplifier.
Doing it your way mixes the charging pulses with the audio current in the shared traces around the rectifier/smoothing. There is a high risk of Buzz getting into the output.
Hi Alex,

Version 1.1 look better than 1.0, good work.

I agree with Andrew that the routing of the power rails can be improved. I have highlighted one possible routing in pink.

I also suggest that the 24V AC quik-on can be moved a bit closer so that their holes are 5mm apart. People can use screw-on terminal connector with 5mm lead spacing if they wish to.

I did a quick check with the layout, the routing are spot-on.

ZD1 should be ZD2 & vice versa; the polarity of the zeners & the 47uF capacitors are reversed.

Cheers, Stanley
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Last edited by sng001; 11th August 2011 at 01:02 PM.
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Old 11th August 2011, 03:36 PM   #156
stoc005 is offline stoc005  United States
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Default Simulation.....

I have simulated the circuit shown in #141 from Lazy Cat. I had to decrease R13 to 7.5 ohms (from 330 ohms) to get the no signal bias current to under 200ma. I guess my models of the lateral fets ALF16N20W and ALF16P20W have pretty low Vgs requirements. Each is around .5 volts Vgs for less than 200ma. The Cordell models of the 2SK1058/2SJ162 worked about the same in this circuit, no signal. Initially I was getting 54A, no signal. Still, I checked the FET datasheet and .5 volts Vgs is about right for this current. I like the ALF16N/P20W because those parts are easy to obtain, cheap here in the US and the fact that they are 16A parts.

Overall, still a well behaved amp and very wideband. But, IMHO, it IS an experimental design. Has anybody shorted out the REAL output to see if it survives? Many designs, like this one, on this and other forums have all SC and SOA protections omitted for many reasons, usually sonic.
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Old 11th August 2011, 03:36 PM   #157
MiiB is offline MiiB  Denmark
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I would much prefer two capacitor-banks one bank driving the output and one bank with diode separation driving the other stages...then PSU sag will only affect the output stage.. to me this clearly improves the amplifier...
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Old 11th August 2011, 04:31 PM   #158
alex mm is offline alex mm  Romania
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Default PCB rev 1.3

.... thanks to all for helping me to layout the correct PCB and kinds words , I do my best , learning something all time .....
Alex.
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Old 11th August 2011, 06:14 PM   #159
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Alex, that is a very neat layout. But really Lazy Cat gets all the fame and applause I merely added two drivers. This remains the Lazy Cat amp.

Kindest regards

Nico
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Old 11th August 2011, 06:18 PM   #160
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Hi Michael,

I agree with decoupling the front end from the power end. I have learnt a trick from Hugh to simply decouple it with a diode and capacitor that way the front end supply remains very stable, regardless of sag caused by the power stage. Sag is usually pretty brief and only occurs during heavy current passages.

Regards

Nico
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