Hum issue with the Gryphon Legato Legacy

llsaw

Well-Known Member
Feb 25, 2016
65
1
138
I received my Legato Legacy early last week and while the sound has been great I've been afflicted with a strange hum problem which after extensive troubleshooting is caused by the Legato Legacy's phono picking up noise from it's power supply. First some details of my setup. I have two 4 tier hifi racks set up side by side. If you are standing in front and looking at my system, on the left hand side rack, top shelf is my CD player while bottom shelf is my Gryphon Diablo 300 int. amp. I removed the shelf immediately on top of my amp for better cooling so this means the left 4-tier rack is now only 3 tier. On the right hand side rack, top shelf is taken up by my Kronos Sparta turntable while bottom shelf was initially taken up by my Entreq ground box.

Upon first install the Gryphon Legato Legacy's phono was placed on the rack underneath my CD player (left hand side rack) while the Legato Legacy's power supply was on the same tier/level but on the other (right hand side) rack underneath the turntable. With this setup the hum was audible from my listening position. After extensive grounding/ground loop troubleshooting which also included replacing both the Legato Legacy and its power supply with the ones from my dealer we are 100% sure the problem is caused by the phono picking up noise from the power supply. I do not have any hum with the power supply on the floor behind my hi-fi rack but this location is not convenient long term as the power supply is now sitting in from of my staircase. Finally I moved the phono to the right hand side rack bottom tier/shelf while the power supply was relocated to the left hand side rack tier beneath the CD player. With this the hum was reduced by 90% and now only audible when I put my ears close to the speaker.

My questions are whether the Legato Legacy is designed for side by side placement and should I relocate it to the same rack (both phono and power supply on the same rack but different shelves) to eliminate the last 10% of the hum? The Legato Legacy is on the same shelf different tier at my dealers and is dead queit there. Would appreciate thoughts and advice from fellow Gryphonistas, dealers, etc familiar with the Legato Legacy.
 
What phono cable are you using ?
Has the cable manufacturer followed Gryphon's instructions exactly ? Details are in the Owner's Manual. Connection is slightly different from normal.
 

llsaw

Well-Known Member
Feb 25, 2016
65
1
138
Hi Philip,

The tonearm cable is a Gryphon Guideline terminated by the dealer. I've changed the tonearm cable during troubleshooting and ascertained that it is not causing the problem.
 

Fineito

Well-Known Member
Nov 23, 2013
21
19
298
This will sound crazy, but I had a phono hum with my old Audio Valve Baldur amplifiers, and I solved it by wrapping the phono cables with aluminum foil. It took me a long time to figure out that was the cause. The idea came from the Tweak Geek. It worked for me. You have nothing to lose to try it. Tom.
 

llsaw

Well-Known Member
Feb 25, 2016
65
1
138
Great suggestion Fineito! I will certainly try this out. I was also thinking about foil or some sort of a shield for the phonostage or its power supply.
 

llsaw

Well-Known Member
Feb 25, 2016
65
1
138
Yes! Picture of my tonearm cable. Also used my dealers cable and still same hum. The Legato Legacy is dead quiet at his place.

36176198.jpg
 
Last edited:

llsaw

Well-Known Member
Feb 25, 2016
65
1
138
Unfortunately yes. I've managed to reduce the hum to 10% or less. You can only hear it now when you place your ear next to the speaker drivers. Would be perfect to eliminate the final 10% though.
 

Fineito

Well-Known Member
Nov 23, 2013
21
19
298
Your welcome, LLsaw. It took me a long time to find the source of the hum in my system with the Baldurs. I tried physical relocation of the phono stage I was using at the time (Wavac LCR), floating the AC, connection to other AC outlets, etc. Nothing solved the problem. I was tearing my hair out. Oviously, my phono cables had never moved! Then I tried the foil and it worked. I could not believe it. Obviously, I was getting EMF from the big Baldur transformers. Since then, I have gone to all Concert Fidelity equipment (amps, pre-amp, phono, DAC), and no problems. Tom.
 

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