I don't have any audible hum even if I place my ear 1" close to speaker driver.
I have done like below, please note I implemented discrete rectifier board. You can replace it with standard bridge rectifier.
Power Supply Connections:
[picture are not in scale, just image representation for understanding.]
Mains to Rectifier:
Rectifier to Filter Board with Ground Isolator:
Earth ground must be connected nearest point in chassis where PS ground will connect through isolator explained below.
Ground Isolator to be built for each channel using Bridge Rectifier block and black NTC:
There are NO wires shorted on crossing also with mounting bolts. Please see actual construction - 1. Graphics 2. Actual Construction Top View, 3. Side view.
Please solder in pins properly, not shown in below picture.
@Blink_PT: One more layout difference I found that your PCB is at same level of transformer. I tried to keep input sections and input cables away from mains and secondary wires of transformer.please see it here.
I have done like below, please note I implemented discrete rectifier board. You can replace it with standard bridge rectifier.
Power Supply Connections:
[picture are not in scale, just image representation for understanding.]
Mains to Rectifier:
An externally hosted image should be here but it was not working when we last tested it.
Rectifier to Filter Board with Ground Isolator:
Earth ground must be connected nearest point in chassis where PS ground will connect through isolator explained below.
Ground Isolator to be built for each channel using Bridge Rectifier block and black NTC:
There are NO wires shorted on crossing also with mounting bolts. Please see actual construction - 1. Graphics 2. Actual Construction Top View, 3. Side view.
Please solder in pins properly, not shown in below picture.
@Blink_PT: One more layout difference I found that your PCB is at same level of transformer. I tried to keep input sections and input cables away from mains and secondary wires of transformer.please see it here.
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in your case situation is much simpler - you have two monoblocks , sharing one case and mains switch/fuse/cable
in case of boyz using common PSU for both channels - situation is trickier , often having different complications (or at least amount of it ) in different builds
whatever - trick with "decoupling" one gnd input signal route with resistor and/or joining central grounds of two channels via direct bridge - is most often working
those are old and ancient tricks , I can't even remember where I saw that for first time
in case of boyz using common PSU for both channels - situation is trickier , often having different complications (or at least amount of it ) in different builds
whatever - trick with "decoupling" one gnd input signal route with resistor and/or joining central grounds of two channels via direct bridge - is most often working
those are old and ancient tricks , I can't even remember where I saw that for first time
When in doubt/trouble, follow what Papa did or sugested in the original paper. The ground isolator was described in the F5T article . In the original F5, the ground was connected via a NTC only and apparently work too.
My 2 cents.
Regards,
My 2 cents.
Regards,
Transformer question... I'm planning to buy transformers from Toroidy. They offered me a price for a normal transformer and an audio grade transformer.
This is what they write about the audio grader transformer:
This is what they write about the audio grader transformer:
I used to buy normal transformers for my amps. Never had any complaints about them. So I was wondering if there is any benefit in using "audio-grade" transformers. Is it, soundwise, a big difference?
How much more money? That's the real question.
It's a higher-quality and specification transformer, ask yourself if you want to pay for the 'better' transformer.
I would buy it, merely because it has the shield.
It's a higher-quality and specification transformer, ask yourself if you want to pay for the 'better' transformer.
I would buy it, merely because it has the shield.
Price is almost double. 
Does anybody know wether NP uses shielded transformers in his products?
Does anybody know wether NP uses shielded transformers in his products?
This image is a Toroidy, will come a week ago. It came without magnetic shielding because I asked (increased another 2-3 cm in diameter). It has a small mechanical noise by opening the lid of the box.
Comes with electrical protection, grounding wire, and the center with expoxi and mounting flanges.
You should ask with flexible connections, but comes standard with solid core wire.
Attachments
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I also have grounding issue, small buzz. I tried Zen Mod's tricks. Now buzz is in left speaker only. Amplifier sounds better then expected . Zen Mod do you have any more tricks? Buzz as you said fet still works. I broke fet while drilling to enlarge hole for screw.
I would use some high temperature epoxy and glue the pieces back in place, if it does still work.
B Weld 8265S Weld Compound - Epoxy Twin Pack : Amazon.com : Automotive
Rush
Glued with epoxy steel J B Weld before installation. Seemed to work well. I hope I can get the screw out later as I did not want to wait for the glue to dry .Greedy boy has no patience.