Tube DIY Asylum

The sound for this setting, low Ra

1.64.133.143

Eric Chan

Hi Folks,

Allen Wright designed the line amp using 6dj8 with 2.2K cathode resistor without bypass, the effective R of the tube is around 80K, but it use only 25K plate load resistor.

Old school told us the plate load resistor at least 2.5 times of the tube resistance, but now is only 0.25 times

What would the sound and tech spec would be in this configuration？

Follow Ups:

RE: The sound for this setting, low Ra - Eric Chan 05:01:23 07/25/23 (0)
Thx for both gentlemen for given information
RE: The sound for this setting, low Ra - Tom Bavis 09:38:04 07/24/23 (1)
Distortion would be low due to the negative feedback. The plate curves become almost straight lines.
- RE: The sound for this setting, low Ra - Tre' 12:10:13 07/24/23 (0)
  .
  Have Fun and Enjoy the Music
  "Still Working the Problem"
  - https://www.passlabs.com/technical_article/audio-distortion- (Open in New Window)
RE: The sound for this setting, low Ra - Tre' 06:42:51 07/24/23 (0)
I would guess a lot of harmonic distortion somewhat covered up by the local current feedback of the unbypassed cathode resistor.

Rolled off highs do to the high output impedance of the stage having to drive any stray capacitance plus Miller capacitance of the next stage.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

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