Pin1 of XLR, both at the Source and at the Receiver MUST be connected to Chassis. Not to audio.
No !
Pin 1 - Chassis
Pin 2 - Hot
Pin 3 - Cold
Hot and Cold are the two phases of the signal.
Both, or one, can have a signal voltage.
One or none can have zero volts of signal.
Pin 1 problem is pretty well known
however , connecting pin 1 to audio GND is troublesome in some cases , while connecting pin 1 to chassis is troublesome in some other cases
go figure , and decide where and about what you are talking - few apparatus home audio , or sound studio ....... later one having dozens and dozens of XLR connections , but also necessary sole audio dedicated safety ground , which quality and execution is strictly and clearly regulated
however , connecting pin 1 to audio GND is troublesome in some cases , while connecting pin 1 to chassis is troublesome in some other cases
go figure , and decide where and about what you are talking - few apparatus home audio , or sound studio ....... later one having dozens and dozens of XLR connections , but also necessary sole audio dedicated safety ground , which quality and execution is strictly and clearly regulated
differential and balanced are the same.
Unbalanced and balanced are the two alternatives.
Balanced takes Pin1 to Chassis.
The receiver amplifies/processes the DIFFERENCE between the two inputs on Pins 2 & 3
Unbalanced uses Signal Hot and Signal Return.
The receiver amplifies/processes the DIFFERENCE between the two inputs on Pins Hot and Return.
If one wants to the unbalanced signal can use an XLR.
Signal Hot could use Pin2, Signal Return could use Pin3. Pin1 would still be reserved for Chassis.
Note how similar the two alternatives are.
The Biggest difference between Unbalanced and Balanced is that Signal Return needs a reference voltage to the Output Return.
Unbalanced and balanced are the two alternatives.
Balanced takes Pin1 to Chassis.
The receiver amplifies/processes the DIFFERENCE between the two inputs on Pins 2 & 3
Unbalanced uses Signal Hot and Signal Return.
The receiver amplifies/processes the DIFFERENCE between the two inputs on Pins Hot and Return.
If one wants to the unbalanced signal can use an XLR.
Signal Hot could use Pin2, Signal Return could use Pin3. Pin1 would still be reserved for Chassis.
Note how similar the two alternatives are.
The Biggest difference between Unbalanced and Balanced is that Signal Return needs a reference voltage to the Output Return.
Balanced line - Wikipedia, the free encyclopedia
From the above sited link: "Lines carrying symmetrical signals (those with equal but opposite voltages to ground on each leg) are often incorrectly referred to as "balanced", but this is actually differential signaling. Balanced lines and differential signaling are often used together, but they are not the same thing. Differential signalling does not make a line balanced, nor does noise rejection in balanced cables require differential signalling."
If that helps anyone understand? My understanding is that "Balanced" is balanced to GND, Differential is only the difference between two inputs.
From the above sited link: "Lines carrying symmetrical signals (those with equal but opposite voltages to ground on each leg) are often incorrectly referred to as "balanced", but this is actually differential signaling. Balanced lines and differential signaling are often used together, but they are not the same thing. Differential signalling does not make a line balanced, nor does noise rejection in balanced cables require differential signalling."
If that helps anyone understand? My understanding is that "Balanced" is balanced to GND, Differential is only the difference between two inputs.
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I made a change to the power supply on my F4. I wanted to hear the effect and I am extremely impressed with the result.
I had the standard CCRCC supply with 4 X 15000uF caps per voltage rail as per original design. I replaced the complete power supply with only 2 X very large can capacitors 60 000uF each per rail and removed resistors altogether.
All I can say is wow!...a huge improvement on overall clarity. Transformed the F4 which was already great to something very special.
Better coherency and imaging also improved. The only department that did not improve as I hoped is the bass which I feel is not as tight as a great amplifier should have. I don't know if it is a mosfet character compared to BJT on the output or not?
Here are the big can capacitors in my F4
I had the standard CCRCC supply with 4 X 15000uF caps per voltage rail as per original design. I replaced the complete power supply with only 2 X very large can capacitors 60 000uF each per rail and removed resistors altogether.
All I can say is wow!...a huge improvement on overall clarity. Transformed the F4 which was already great to something very special.
Better coherency and imaging also improved. The only department that did not improve as I hoped is the bass which I feel is not as tight as a great amplifier should have. I don't know if it is a mosfet character compared to BJT on the output or not?
Here are the big can capacitors in my F4
In the context of Juma's comment on XLR plug/socket connections, I see differential as the same as balanced.
The Receiver reads/measures the DIFFERENCE between pins 2&3 and processes that difference.
Pin3 can be a signal of inverted polarity or no signal or signal of same polarity as Pin2's signal, which can also be any of the same options. Pin3 can also be the signal Ground reference.
Pin1 is Chassis.
In the case of a balanced F4 (Balanced meaning to differential inputs Balanced to GND) you can operate as a higher power mono block.
Feeding the 2 F4 inputs with a differential signal without GND refrence, produces no noise canceling benifits beyond the sheilding used. The F4 input is not set up to respond to a purely diff inputs any differently than 2 single ended inputs. It's just 2 discrete buffers with inputs refrenced to GND.
Feeding the 2 F4 inputs with a differential signal without GND refrence, produces no noise canceling benifits beyond the sheilding used. The F4 input is not set up to respond to a purely diff inputs any differently than 2 single ended inputs. It's just 2 discrete buffers with inputs refrenced to GND.
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So its seems like I can only bias my amp up to about 110mv. Does this mean that I have done something wrong, or does it mean that I just need lower resistance on some of the resistors? If so does anyone know what I need to change? Also is it possible to run the amp at 110mv bias until I get additional parts?
Thank you
. What would you suggest i increase the resistance to? I am thinking about doubling it.
Yes, the input gets referenced to the output..................................
Feeding the 2 F4 inputs with a differential signal without GND refrence, produces no noise canceling benifits beyond the sheilding used. The F4 input is not set up to respond to a purely diff inputs any differently than 2 single ended inputs. It's just 2 discrete buffers with inputs refrenced to GND.
That is done at the Main Audio Ground. This might be more usually named Signal Ground, especially if the equipment is not a power amplifier.
There is no signal connection to Chassis.