Bottlehead Kits > Smack

How silent should the Smack be?

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M^Cubed:
I just recently finished up building the Smack kit and I have a very light, but noticeable hum. Should any hum be acceptable or should I go through and check resistances again?

The tubes are NOS matched 7119 Amperex with O halo getter. The hum does not change with volume or with/without source connected and with all impedance balanced / unbalanced selection.

Cheers!
 

fullheadofnothing:
What headphones are you using? How many hours of use do the tubes have?

M^Cubed:
The tubes are new from what I understand, so very little (probably about 20 hours at this point)

With the HD800 (128 ohm / Balanced) there is very very close to a black background.

With the HD650 (128 ohm / Balanced) there is a noticeable hum with no music playing.

With the T50rp / Mad Dog ( 32 ohm / SE ) there is a noticeable hum with very low music playing.

This is after letting the amp warm up for about a hour while playing music.

Maybe I should switch to a lower gain 5687 also?

Paul Birkeland:
Did all your voltages look good after you built the amp?

Does the hum vary with your level control?

Will the hum change if you move the Smack around?

M^Cubed:
Level control does not change the hum, and movement does not change it.  I will need to re-check voltages, but everything was good after the build.

Maybe the tubes just need some hours on them.

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