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RE: Transformer type attenuator

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In Reply to: RE: Transformer type attenuator posted by OldNuke on October 13, 2017 at 00:05:07

You need to look at the overall gain structure in your amplification chain and eliminate any devices that add too much gain. Whenever you attenuate a signal you are adding distortion and noise. You have 2Vrms coming from your sources. Determine the input sensitivity of your amplifiers. If it is less that 2Vrms you need no further amplification, simply a volume control, and in fact any further amplification will add noise and distortion.

Follow Ups:

Used a Passive Preamp previously - OldNuke 22:41:27 10/16/17 (7)
I incorporated the transformers and pot into the 300B I'm currently using. I like the sound of this 300B preamp so it would be difficult to go back. Definitely have to consider the system gain and sensitivity of my speakers though.
It's common to put LPad's on tweeters, I just want something better/different from installing a cap,pot and resistor. If all my speakers and amps were equal I could just pad the preamp and be done but I need a tailored control so I would like to see if some 10:1 and 100:1 transformers would be an option.
- RE: Used a Passive Preamp previously - Palustris 09:33:47 10/17/17 (6)
  The sensitivity of the speakers is not part of the gain structure of your amplification chain. What you need to understand is the input sensitivity of your amplifier. If your amplifier reaches full output with less than 2Vrms input, then you need no further amplification in the signal chain since the source will output 2Vrms. I understand that many are willing to accept reduced sound quality so that they can add more "boxes" to the signal chain, I am simply advocating for better sound not more "boxes."
  - RE: Used a Passive Preamp previously - OldNuke 10:31:05 10/17/17 (5)
    Well, yeah, I do have too much gain (and too many amps) but I don't see myself simplifying the system anytime soon. My Stereomours have a gain of 8, input sensitivity of .4v while the Vidar amp has a gain of 22.
    - RE: Used a Passive Preamp previously - Paul Joppa 18:06:01 10/17/17 (3)
      I'm not sure which version of Stereomour you have, but the Stereomour II should generate full power with about 1.17 volts RMS input. The original has a bit more gain.
      
      IIRC, it takes a bit over 0.4v to get 1 watt output - that might have been a mis-communication?
      
      [For anyone who does not already know, I designed all versions of the Paramour/Stereomour amps.]
      - RE: Used a Passive Preamp previously - OldNuke 20:21:53 10/17/17 (2)
        
        In Reply to: RE: Used a Passive Preamp previously posted by Paul Joppa on October 17, 2017 at 18:06:01
        
        Hi Paul,
        I have both versions, I took the .4 from the manuals, page 6 February 3 2014 and 2015 versions (original and version II). I may have reported them incorrectly, here's the info from the original.
        Power 2A3 - 3.5 Watts, 45 - 1.75 Watts
        Hum typically 1 mV RMS, depending upon the output tube used
        Bandwidth: -1dB at 20Hz, -3dB at 50kHz
        Gain: 12.5 at the 8 ohm tap (21.5 dBV)
        Sensitivity: full power at about 0.4v (2A3)
        
        The other one is the about the same except no 45 option.
        I don't think this is proprietary info. Let me know if so and I will delete it.
        
        RE: Used a Passive Preamp previously - Paul Joppa 19:24:27 10/18/17 (1)
        
        In Reply to: RE: Used a Passive Preamp previously posted by OldNuke on October 17, 2017 at 20:21:53
        
        Wow - thanks for alerting me. The manual is in error, that's about the sensitivity of the Stereomour II at 1.0 watts. Must have gotten our wires crossed! I'll alert the team.
        
        My apologies for the confusion.
        
        RE: Used a Passive Preamp previously - Paul Joppa 13:45:22 10/21/17 (0)
        
        In Reply to: RE: Used a Passive Preamp previously posted by Paul Joppa on October 18, 2017 at 19:24:27
        
        I am grateful for the opportunity to catch it and alert others. Thanks!
    - RE: Used a Passive Preamp previously - Paul Joppa 18:00:30 10/17/17 (0)
      I'm not sure which version of Stereomour you have, but the Stereomour II should generate full power with about 1.17 volts input. The original has a bit more gain.
      
      [If anyone does not already know, I designed all versions of the Paramour/Stereomour amps.]

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