In Reply to: Input Sensitivity and Interstage Transformer posted by HKL on October 31, 2003 at 05:50:52:

It's all about system matching and personal biases. I use a TVC normally for volume control, so I need a bit more gain than someone with an active line stage. Even the lovely sounding Raleigh Audio active line stage kit that I sell has relatively low gain (5dB) in its usual connection. However, it has provision for increasing the gain by reconnecting the input transformer for 6dB additional gain for a total of 11dB. My experience in retail audio taught me that most systems have too much gain, not too little, because manufacturers err on the side of more gain than less, because consumers can always reduce gain with the volume control. Unfortunately, that results in a noise and dynamics trade-off if carried too far, though.

I would continue to use an interstage, but use it 2:1+1 or 1:1 for SE. Output tube drive is a critical part of the sound of power amplifiers. The use of wimpy driver tubes with high Rp was never a successful design measure in my hands.

Unfortunately I know of no octal tubes that have 40+ mu and low plate impedance.

Kevin Carter
K&K Audio
www.kandkaudio.com

• Game of Gain - HKL 12:45:37 10/31/03 (9)
  In Reply to: Re: Input Sensitivity and Interstage Transformer posted by KevinC on October 31, 2003 at 07:31:52:

  My experience in retail audio taught me that most systems have too much gain, not too little, because manufacturers err on the side of more gain than less, because consumers can always reduce gain with the volume control. Unfortunately, that results in a noise and dynamics trade-off if carried too far, though.

  Can't agree with you more on this.

  That said, the 5dB gain of K&K Raleigh linestage seems to be surprisingly low to me. I had looked at the schematic at your site a number of times. A very rough thought of a CCS loaded 6N1P should yield a mu around high 20's to low 30's. That's around a gain of 28dB to 30dB.
  
  

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  • Re: Game of Gain - KevinC 13:10:33 10/31/03 (8)
    In Reply to: Game of Gain posted by HKL on October 31, 2003 at 12:45:37:

    You are right about the gain of a 6N1P, but we are stepping the signal down 6dB in the input transformer and 18dB in the output transformer, so the ~30dB from the 6N1P becomes 5dB. Either the input or output transformer ratios can be changed for more gain readily when the kit is built.

    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com
    
    

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    • Any thing gained from stepping down? - HKL 05:53:13 11/01/03 (7)
      In Reply to: Re: Game of Gain posted by KevinC on October 31, 2003 at 13:10:33:

      Thanks for the information.

      Pardon me but can't resist wondering anything gained from stepping down a total of 24dB. Chances are this is not around current as 6N1P is a high current, high mutual conductance tube among twin triodes.
      
      

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      • Lower output impedance, and better driving capability. (nt) - JLH 07:52:23 11/01/03 (0)
        In Reply to: Any thing gained from stepping down? posted by HKL on November 01, 2003 at 05:53:13:

        .
        
        

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      • Re: Any thing gained from stepping down? - Dave Davenport 07:34:18 11/01/03 (5)
        In Reply to: Any thing gained from stepping down? posted by HKL on November 01, 2003 at 05:53:13:

        Hi HKL,

        What is gained is low gain.

        The point is that most people do not need a lot of gain in their system and end up using their volume control from 7 to 8 o'clock. While developing the line stage I listened to all of the different transformer ratios with resulting gain differences. The best sounding was with the low gain. I don't know if this was because of the characteristic of the transformer ratio or because of the characteristics of the amplifier at low gain.

        So what is gained is better sound.

        Dave
        
        
        

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        • That should not only sound good - HKL 15:40:26 11/01/03 (4)
          In Reply to: Re: Any thing gained from stepping down? posted by Dave Davenport on November 01, 2003 at 07:34:18:

          It sounds interesting too.

          Mind if I ask one more question: have the tube choice, say, a lower mu one, been given a thought?
          
          

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          • Re: That should not only sound good - Dave Davenport 20:26:22 11/01/03 (3)
            In Reply to: That should not only sound good posted by HKL on November 01, 2003 at 15:40:26:

            Hi HKL,

            Yes we did audition many tubes along the way. I started with the 5687 and tried several variants on it. Then the ECC99 and 6H30P. I liked the 6H30P, which has about half the mu as the 6N1P, and stayed with it for a while. In this circuit the 6N1P sounds marginally better than the 6H30P so I now use it. There are many factors to consider when designing a circuit; gain is only one. For me, the prime criterion is sonic quality. First get that and then do what you need to do to get your gain target, which I believe should be moderate.

            Dave
            
            
            

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            • What current are you running your 6H30 ? - akltam 17:19:03 11/04/03 (1)
              In Reply to: Re: That should not only sound good posted by Dave Davenport on November 01, 2003 at 20:26:22:

              Did you change any settings when you change to 6n1p.

              Thanks.
              Alan
              
              

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              • Re: What current are you running your 6H30 ? - Dave Davenport 18:21:20 11/04/03 (0)
                In Reply to: What current are you running your 6H30 ? posted by akltam on November 04, 2003 at 17:19:03:

                Hi Alan,

                I ran the 6H30P at 20mA per side and the 6N1P at 8mA per side.

                Dave
                
                

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            • Thanks for all the information <nt> - HKL 06:08:52 11/02/03 (0)
              In Reply to: Re: That should not only sound good posted by Dave Davenport on November 01, 2003 at 20:26:22:

              
              
              

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