XLR phase inversion. Purpose?

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
10,848
Location
Connecticut
Tagline
BOT
#21
Jim do you have the schem for the Aragon you have? Does it have balanced outs?
No, and no.

And I no longer have it. Sold to an AK member.

I do still have the D2A (not balanced either) but not the 47k which is what I assume you were asking about.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
10,848
Location
Connecticut
Tagline
BOT
#23
Even most of the "good" stuff are all single-ended inside, with converters on the front and back ends that "create" a balanced signal...

Back to the 47k, it is an excellent (simple) design phono pre that served me a LONG time before being replaced with the Wyn Palmer design. They are not easy to find second-hand because people don't let them go!
 

Hexis22

Chief Journeyman
Joined
Dec 28, 2022
Messages
715
Location
Wisconsin
#24
Even most of the "good" stuff are all single-ended inside, with converters on the front and back ends that "create" a balanced signal...
Yes, this conversion from balanced input to single-ended gain stage and back to balanced output using phase splitter circuits within different preamps can cause significant audible degradation. All this so marketing can advertise “Balanced” capability.

This is why many non-fully balanced preamps sound better using single-ended inputs and outputs.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
10,848
Location
Connecticut
Tagline
BOT
#25
This was/is a problem with Wyn's phono preamp design.

If ever there was an argument for a balanced line, it's from a cartridge to phono pre. I REALLY wanted to run balanced in from the table, and even made up special balanced cables using those mini XLR jacks found on headphones (perfect for the application) ... But the noise and distortion within the preamp was significantly higher with this option in the phono pre. It did support balanced out, but at that point, all the noise that would be picked up and amplified has already happened...

I've been pushing him to do a truly balanced line amp but he's not excited about the project and has similar issues with the design... I was going to get a pair of JC-2 preamps and use - one for each channel - to slap something together. But I think my efforts will fall very short of what Wyn can accomplish.
 

laatsch55

Administrator,
Staff member
Joined
Jan 14, 2011
Messages
74,886
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#28
Balanced in but, in reality, single ended out...
I saw the only difference between Chassis ground and signal ground was a 100 ohm resistor to the chassis for the sig ground... Is that really effective against ground loops Joe?
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
14,016
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#29
I saw the only difference between Chassis ground and signal ground was a 100 ohm resistor to the chassis for the sig ground... Is that really effective against ground loops Joe?
Probably Lee if the receiving end has a true differential receiver in it, such as an INA134

1718930888212.png
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
14,016
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#36
What are they sensing for?
Hi Lee
If there is an offset in grounds between sending and receiving units, you can attach the receiving ground levels to the Sense lines and it will adjust the ground level of this differential driver to that of the receiver. Most often, these sense lines are left open with no connection.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
10,848
Location
Connecticut
Tagline
BOT
#37
How much noise and distortion do these typically add? It was a deal breaker for Wyn but I don’t know how he implemented it for the output. It wasn’t another chip anyway…
And input was always single-ended
 

Gepetto

Administrator
Staff member
Joined
May 15, 2011
Messages
14,016
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#38
How much noise and distortion do these typically add? It was a deal breaker for Wyn but I don’t know how he implemented it for the output. It wasn’t another chip anyway…
And input was always single-ended
Not zero Jim.

Differential transmission adds components which always degrade, not improve on sound quality. If you have long runs of cables, especially in noisy electrical environments, differential can help because it has better common mode rejection capability. But in most short run, quiet audio system environments, single ended has fewer components in the signal path introducing noise and distortion.

However, high end stuff needs to have a balanced input for some reason or another. So you are required to add it regardless of outcome or if it is ever utilized.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
10,848
Location
Connecticut
Tagline
BOT
#39
I prefer less and the performance Wyn gets from his phono pre is pretty well known and documented at this point.

But that microvolt input from cartridge to preamp is the perfect place to utilize a balanced line. Any noise picked up gets amplified hugely.

Micro (on their X suffix arms and head shells) use coaxial cable for the cartridge to reject noise. I have it, it’s quiet, but strikes me as odd to use half the signal as a shield with a coil at the end. I guess it works but looking at the entire circuit it just seems odd.
 
Top