Why don't you use the standard method instead of trying to use the feedback its always worked for me ?
what is the standard method? Note: this is original KSA-50 WD. The HBR will be eventually my mod.
Separating the output section earth return from the input earth return .
A separate earth for the first half of the power amp and a separate earth for the output devices .
This has been well talked through on EW/WW by many engineers its a proven fact not hypothetical /virtual - heavy return currents in the output devices are not returned to the sensitive input active devices.
Ten ohm resistor between the two earth returns .
While I have seen JLH use the feedback as a balance control in one of
his designs it was not a design he stuck with and did it only as an "innovation " to show it could be done.
JLH in his day ( and mine ) didn't use the term --HBR which I take is a modern language variation of a "noise reducer " .
But "proof is in the pudding" as they say in the UK and I take it Australia as well if you are my generation --try it and see and if it achieves superior reduction to the standard version please show by test results using technical equipment that it is so--not by ear.
A separate earth for the first half of the power amp and a separate earth for the output devices .
This has been well talked through on EW/WW by many engineers its a proven fact not hypothetical /virtual - heavy return currents in the output devices are not returned to the sensitive input active devices.
Ten ohm resistor between the two earth returns .
While I have seen JLH use the feedback as a balance control in one of
his designs it was not a design he stuck with and did it only as an "innovation " to show it could be done.
JLH in his day ( and mine ) didn't use the term --HBR which I take is a modern language variation of a "noise reducer " .
But "proof is in the pudding" as they say in the UK and I take it Australia as well if you are my generation --try it and see and if it achieves superior reduction to the standard version please show by test results using technical equipment that it is so--not by ear.
Sure you can do the HBR mod, I have done this on several other amps with common PS for both channels. I have not noticed any benefit on mono-blocks (separate PS for each channel).
duncan2: do you have an example? I'm not sure where you put the 10 ohm resistor, it might actually be the same thing as HBR if you put the resistor on the ground to the front end of the amp.
duncan2: do you have an example? I'm not sure where you put the 10 ohm resistor, it might actually be the same thing as HBR if you put the resistor on the ground to the front end of the amp.
Yes, that seems like taking it a bit further with all front end grounds going through the HBR. Not sure, but I think the result should be basically the same.
I have already added the 10R resistors between earth and GND (from caps). It helped and I could hear it but still not happy when measured.
What I can assure you about-- JLH had articles about the above design printed in EW/WW to be discussed by many audio design engineers of note none of them had an issue or criticized his earthing techniques .
If you read his articles he went to great lengths to discuss this ---no opposition occurred --many technical tests performed NOT relying on listening alone ---proved his point .
If you read his articles he went to great lengths to discuss this ---no opposition occurred --many technical tests performed NOT relying on listening alone ---proved his point .
no exactly! Sorry I just looked closely at this schematic. In my case it is difficult to implement with current PCB i have. So, my resistor is only connected between Earth and 0V at capacitors reservoir.
How would you do it with the KSA-50? Would you be able to mark that resistor there?
The HBR can be remove if you're using dual mono or mono block layout - there is no ground loop between 2 channel which is reason of appearance of HBRs.
I actually want to add HBR as i have issues with ground loops. It is dual mono design with two transformers..
Arttti-- exactly as the JLH circuit shows ----ALL earth returns AFTER the bias in the Krell go to earth #2--IE=output devices and all filtering etc.
ALL earth returns BEFORE the output devices go to earth #1.
BOTH joined together by a 10ohm resistor .
When I say all I mean all even though it means more work for you --don't skimp.
ALL earth returns BEFORE the output devices go to earth #1.
BOTH joined together by a 10ohm resistor .
When I say all I mean all even though it means more work for you --don't skimp.
Does anyone know if the Pinkmouse Krell Clone Boards have this 10 ohm resistor on PCB?
The 10 ohm resistor goes on the signal ground side to mains earth?
I have always had a little hum on my KSA-50 Clone amp (not monoblocks), I was always sure it just needed better PS filtering...
The 10 ohm resistor goes on the signal ground side to mains earth?
I have always had a little hum on my KSA-50 Clone amp (not monoblocks), I was always sure it just needed better PS filtering...
member bonsai's presentation is well worth a read to help figure the root cause:
http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf
http://hifisonix.com/wordpress/wp-content/uploads/2019/02/Ground-Loops.pdf
Pink, have you ever heard of an engineer following instructions? 🙂
I did wire it as you instructed - I still think I need to add that inductor to the power supply first - PSU Designer modeled existing CRC coincides with around 200mv ripple I think I am getting....drops quite a bit with a 2.5mh inductors added for CLC ...
Reading the presentation, I am surprised it sounds as good and quiet as it is! I see my wiring mistakes everywhere...
I did wire it as you instructed - I still think I need to add that inductor to the power supply first - PSU Designer modeled existing CRC coincides with around 200mv ripple I think I am getting....drops quite a bit with a 2.5mh inductors added for CLC ...
Reading the presentation, I am surprised it sounds as good and quiet as it is! I see my wiring mistakes everywhere...