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Valve Itch phono
Valve Itch phono
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Old 18th September 2018, 03:16 PM   #3131
Salas is offline Salas  Greece
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Valve Itch phono
This is how it simulates for response with anti-Riaa at the input, C4 0.1u, R8 820k, C6 2.2u, and a 20k output load (a dcb1 buffer pre with its 20k pot for instance)
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Old 18th September 2018, 03:19 PM   #3132
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Thanks Salas, please could you simulate C4 0.1uF C6 3.9uF & 100K output load?
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Old 18th September 2018, 03:23 PM   #3133
Salas is offline Salas  Greece
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Valve Itch phono
Here it is
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Old 18th September 2018, 03:26 PM   #3134
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Looks like the same, right?
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Old 26th September 2018, 09:13 PM   #3135
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Still some hum but using scope don't see any AC oscillation. I connected the mu metal sheet covering the tube sockets to chassis ground waiting to lower the hum.
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Old 27th September 2018, 06:45 PM   #3136
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Lowered the hum but still some hum when volume pot starting to 1 to 2 o'clok. It seems needs more screening.
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Old 28th September 2018, 12:15 PM   #3137
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Link to youtube YouTube
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Old 28th September 2018, 01:03 PM   #3138
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Scope don't show ripple no other strange artifacts.
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Old 28th September 2018, 04:46 PM   #3139
Salas is offline Salas  Greece
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Valve Itch phono
Maybe its a ground loop when connected to the system. Because the buzz in the video clip sounds strong enough and should have been captured by the scope.
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Old 29th September 2018, 08:56 PM   #3140
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Now I'm using a volume with switch ladder resistor of 100K so the source always see 100K, i'ts in a small box between the Itch and the preamp: could be the source of ground loop?
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