Posted by robber (A) on October 13, 2007 at 19:44:17

I picked up a nice 2nd hand fp2 recently and really like the sound. It is fully loaded and even has hovland caps. I have an expensive Levinson ss pre that has nothing on the fp imo.

The thing is that I really hate the ergonomics of it. The Dual mono stepped attenuators mostly.
Which brings me to my question.

I have a nice Monolithic sound passive pre lying around and I was wondering why I could not simply feed its output into one of the FPs input and set and forget the gain on the foreplay.

I understand that there are many reasons why this is not ideal, but is there any reason that would be a show stopper? I suppose I should also note that the Monolithic has a buffer itself (it needs ac) in order to drive long cables and match impedance.

If this is kosher, and II end up liking the sound, the next question would be what would have to be done to the foreplay to bypass the input selector and volume pots.

Thanks

-Rob

Edits: 10/13/07

• RE: passive pre feeding foreplay 2??? - Paul Joppa 18:34:57 10/14/07 (1)
  In Reply to: RE: passive pre feeding foreplay 2??? posted by robber on October 13, 2007 at 19:44:17

  There should be no problem.
  
  I assume that the Monolithic works fine when unplugged, as long as the gain is less than unity. In that case, I would unplug it to reduce the noises that might creep in.
  
  I would strongly suggest the shortest, lowest capacitance cables between the passive and the FP. Driving cable capacitance is the Achille's heel of passives.
  
  It should be easy enough to bypass the FP's gain and switching.
  
  

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  • RE: passive pre feeding foreplay 2??? - robber 12:22:32 10/15/07 (0)
    In Reply to: RE: passive pre feeding foreplay 2??? posted by Paul Joppa on October 14, 2007 at 18:34:57

    Thanks for all the replies.
    
    I tried it out and it sounds fine. I have to do some a/b to determine what if any difference there is.
    
    The Monolithic is such a pleasure to operate and it has never been anything but completely transparent. I am willing to bet I cannot evev hear a difference with it in and out of the chain.
    
    thanks again
    
    

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• Can always put a stero volume pot in it. - Paully 08:20:55 10/14/07 (0)
  In Reply to: RE: passive pre feeding foreplay 2??? posted by robber on October 13, 2007 at 19:44:17

  That is what I did (with some help).
  
  

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• I don't know anything about your passive pre - JC 20:09:36 10/13/07 (2)
  In Reply to: RE: passive pre feeding foreplay 2??? posted by robber on October 13, 2007 at 19:44:17

  but I would speculate from your description that it is not entirely passive. And, while I can't, pending more info (like, what is the output inpedance of the passive, for instance), I can't think of any reson not to hook it up as you suggest for a trial.
  
  It may be, though, that you are simply adding a layer where you don't really need one. Perhaps different attenuators for the FP 2 might be a better approach. IIRC, the original FP 2 used 100kOhm attenuators.
  
  But, to try it out, I would suggest turning the attenuators on the FP to their loudes position, thus removing them as much as posible from the circuit, and letting your passive do all the attenuation of the source. That is how I would start, at any rate. If you can run down more info on the passive, that would be very helpful.
  
  

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  • RE: I don't know anything about your passive pre - robber 20:18:02 10/13/07 (1)
    In Reply to: RE: I don't know anything about your passive pre posted by JC on October 13, 2007 at 20:09:36

    Thanks for your post. Much obliged.
    
    The Monolithic is a very unique box. It is completely passive until the volume control hits 12 o clock. Then the active stage kicks in. The active stage never gets a chance in my system.
    
    Another part of my reasing is that I spent a while a/b testing this in passive mode versus straight into my amps and could never decipher any difference. So to my ears, this thing has no sound.
    
    Here is a link;
    http://www.monolithicsound.com/PA1.html
    
    Thanks again
    
    

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    • OK, they don't really spec an output impedance, - JC 21:07:54 10/13/07 (0)
      In Reply to: RE: I don't know anything about your passive pre posted by robber on October 13, 2007 at 20:18:02

      and, I imagine that might depend on whether or not on engages the "gain" portion of the circuitry.
      
      But, assuming the input impedance of your FP 2 is, in fact, 100k or better, and, presuming that the maximum output impedance of the passive is approximately 10kOhms or less, then it may just be that it will all work out.
      
      That, of course, is a lot of assumptions, but I really can't see that you could hurt anything by trying. Chances are, though, that you won't have a lot of control range, 'cause unless the FP 2 has been modified, it will have a lot more gain than you need. You may want to try BOTH sets of attenuators at their minimum settings at first, then experiment with what you consider to be the optimum setting on the FP 2, given good sound and a good control range from the passive.
      
      Once you have established this, you may wish to go no further. Or, if you want to bypass the selector and attenuators on the FP 2, you will have a bit more info.
      
      

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