• multiple gain stages - Dave Davenport 14:39:14 05/28/04 (2)
  In Reply to: Kevin - any comments? posted by Max Dissipation on May 28, 2004 at 10:26:59:

  Hi Max,

  You commented: "I must say I still have a problem with the idea of two gain stages....."

  Well, you are preaching to the choir when it comse to excessive gain in the signal chain. However, multiple gain stages are okay if they are reasonable. Like for example, phono cartridge to a phono preamp to a line preamp. Each does its own job to adjust the levels for its inputs. So less-than-a-volt DAC output to a DAC preamp to a line preamp might be a reasonable thing.

  Dave
  
  
  

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  • Re: multiple gain stages - Max Dissipation 22:39:29 05/29/04 (1)
    In Reply to: multiple gain stages posted by Dave Davenport on May 28, 2004 at 14:39:14:

    Hi Dave
    I hear what your saying, and of course many systems do have a DAC output stage and a line stage. But right now I have the output from the DAC chip (+/- 0.27V) and with just a TVC I'm operating about in the middle of my volume range. So in my particular case, I know I don't need any gain.
    But I know that there is still the issue of matching source and load impedances along the chain. I'm thinking that by having the DAC and linestage in one box I'll give the DAC an easier load - no long cables to drive. And so this will work better with no DAC stage or a passive DAC stage.
    Having said all that, I'm aware that you & Kevin have actually 'been there & done that' with the development of the DAC and the linestage, whereas my comments are 'speculative'.

    Max
    
    

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    • Re: multiple gain stages - Dave Davenport 11:13:24 05/30/04 (0)
      In Reply to: Re: multiple gain stages posted by Max Dissipation on May 29, 2004 at 22:39:29:

      Hi Max,

      Well, you have the advantage of being able to tailor a solution for your system while we have to provide a more general solution. Keep tuned and we will feed out ideas as they come.

      Dave
      
      
      

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• Re: Kevin - any comments? - KevinC 12:10:32 05/28/04 (2)
  In Reply to: Kevin - any comments? posted by Max Dissipation on May 28, 2004 at 10:26:59:

  I agree with what Dave has written. However, here is a half-crazy idea.

  Why not use an LL1674 (1+1:4+4) in the manner of the passive transformer output stage after the DAC board to get DAC gain, do I/V and do the input phase splitting for the "rest" of the line stage circuit; and for all other inputs (like tuner, phono) switch in a different LL1674 configured for the normal 4:1+1 of Dave's line stage circuit. It's more transformer cost (yes!!!), but it avoids duplicate gain stages. This sounds facitious, but is meant as a serious proposal.
  
  
  

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  • Re: Kevin - any comments? - Max Dissipation 14:44:33 05/28/04 (1)
    In Reply to: Re: Kevin - any comments? posted by KevinC on May 28, 2004 at 12:10:32:

    Hi Kevin
    It doesn't sound facetious at all, I like it! Thanks!
    So would I have a toggle to switch between DAC and other sources, and then a source select to switch *between* the other sources?
    Max
    
    

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    • Re: Kevin - any comments? - KevinC 13:21:39 05/31/04 (0)
      In Reply to: Re: Kevin - any comments? posted by Max Dissipation on May 28, 2004 at 14:44:33:

      Basically, yes. You could do it with one fairly complex switch or even use relays, but you would be switching at least two wires per channel to take the DAC input in and out in addition to the usual 2 wires per channel for balanced sources.
      
      
      

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