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RE: DHT 01a tube preamp

138.130.52.161

In Reply to: RE: DHT 01a tube preamp posted by Tre' on February 15, 2025 at 15:40:39

Capacitance of my cables is 175pF (0.175nF). Quite low.
| retro-thermionic |

Follow Ups:

RE: DHT 01a tube preamp - Tre' 16:15:25 02/15/25 (1)
With an output impedance of 330K playing into 175pf the -3db point of the low pass filter will be 2756Hz. The -1db point will be at 1378Hz.
That is a massive lose of high frequencies and it is only going to get worse when you add in the Miller capacitance of the first stage of your power amp.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
- https://www.omnicalculator.com/physics/low-pass-filter (Open in New Window)
Edits: 02/15/25
- Correction - Tre' 18:29:18 02/15/25 (0)
  Correction, with the 100k resistor in parallel with the 330k ohm resistor the output impedance is 76744 ohms so the -3db point of the low pass filter is 11850Hz. Better but still a lot of high frequencies lost in the audio band.
  
  Tre'
  Have Fun and Enjoy the Music
  "Still Working the Problem"

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