Humming noise with new La Figaro 339
Apr 28, 2020 at 8:06 PM Thread Starter Post #1 of 3

GLiverpool

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Afternoon everybody

My new La Figaro 339 headphone amp was delivered on Monday.
I have the following queries:
Is it normal for the whole unit to get very hot to the touch during usage?
Is it normal for the unit to have an audible hum that can be heard up to 3 feet away? This could not be described as loud but can be heard.
There is a slight hum in the left signal path. The right signal path is silent. If there are momentary silent periods during playback the left side hum can be heard. Any ideas re cause or solution please.
I am using the stock driver tubes (am waiting for tungsol and rca red to arrive from USA). Have and am using the following power tubes:
Mullard 6080 Thomson 6080 Svetlana 6as7g
the hum is the same with each set of tubes. Headphones are brand new Sennheiser HD 650. Have connected them to the television and no hum was present. Would very much appreciate your opinions. Bought from doukmall on EBAY so still have time to return.
 
Apr 28, 2020 at 9:07 PM Post #2 of 3

Monsterzero

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Tubes can introduce hum that can be heard thru the headphones themselves. Best way to test this is to swap the left tube to the right side and vice/versa. If the hum swaps sides then its most likely a tube that needs its pins cleaned. Fine grit sandpaper usually suffices,but some use alcohol or Deoxit on especially grimy pins.

Note: if you ujse alcohol or any other liquid to clean pins wait until the pins are completely dry before re-inserting into amp. :)

If the hum doesnt swap sides then its most likely not a tube issue and could be an amp issue.
Tube amps do get hot for sure,but Ive never noticed an audible hum coming from the amp itself on any of the OTLs Ive owned,including the WA2,GOTL and the 339.
 
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Apr 8, 2021 at 12:06 AM Post #3 of 3

xmdkq

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Check first, power on without any signal source, and then listen to see if there is any. If not, it is brought by the outside. I have encountered this situation in the past.
 

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