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    Maybe a preamp is a good idea after all...

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    j beede

    Posts : 328
    Join date : 2011-02-07
    Location : California

    Maybe a preamp is a good idea after all...

    Post by j beede on Sat Mar 26, 2011 9:59 pm

    I have run my Marantz special edition CD player "straight in" for years--I built a small attenuator using an ALPs stereo pot for level control. Earlier today while testing my recently restored PAS-2 I noticed details in a Reference Recording cut that I hadn't heard before--finger sounds and plucking detail in a harp recording. I pulled the PAS out of the loop and ran the CD player straight in and the detail was muted, the recording sounded very ordinary. I may need to keep this PAS around until I get a handle on this surprise. I guess this is why people use tube buffers. Anyone else ever try this experiment?
    ...j

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: Maybe a preamp is a good idea after all...

    Post by frank on Sun Mar 27, 2011 1:17 am

    My experience may not exactly apply to your situation. I have found that unless you need the gain, you are better off with the passive volume control if you want to hear as much of the detail as possible. Any time I used an active preamp it has added noise and masked the more delicate aspects of the recording.
    All my experience is with solid-state preamps. I had an old Hafler DH-100 that I bypassed all the active circuitry, just using the pot for level control and found improved clarity and connection to the music. More recently I have an Aragon 18K preamp that I replaced with a Placette passive linestage (I think this uses relays to switch in and out ladders of Vishay resistors). In this case again I found increased clarity and the uncovering of otherwise hidden details (pages turning, shuffling of feet, etc.).
    From what I have read the "experts" say that what you lose is "dynamics" with a passive level control. I have not missed any such loss. As an aside, I have a friend who manages a high-end stereo store. He tried to talk me out of buying the Placette for that reason. I just decided I was unwilling to spend the 3k+ I felt it would take in order to get the degree of sound quality I wanted (the Placette ended up at 1800). After putting the Placette in my main system he had to say he didn't notice any loss of dynamics.
    Perhaps the preamp is compensating for some other signal loss(very wild guess)? Are you using super-long interconnects anywhere between the source and the amp? It could be that your source isn't up to the task of driving your amp. You said you had been using your passive setup for quite some time maybe when you connected the preamp what you really did was wipe off the corrosion on your RCAs???
    'Frank


    Last edited by fswidecki on Sun Mar 27, 2011 1:26 am; edited 1 time in total (Reason for editing : additional info)

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: Maybe a preamp is a good idea after all...

    Post by frank on Sun Mar 27, 2011 1:55 am

    OK, I got caught up in the writing and forgot what I read. Is that like talking instead of listening? So far, the buffer idea makes as much sense as any thought I have to add.
    'Frank

    j beede

    Posts : 328
    Join date : 2011-02-07
    Location : California

    Re: Maybe a preamp is a good idea after all...

    Post by j beede on Sun Mar 27, 2011 12:43 pm

    I never gave much thought to the source impedance of the CD player, it seemed more than adequate to drive the amplifier's input Z. Apparently not. Thinking about it now, the input Z associated with a preamplifier line input is probably larger and more standardized than power amplifier input Z. Power amp input loads can vary quite a bit from design to design and from technology to technology. Compunding that is the reality that the source impedance of a typical preamp is probably smaller than the source impedance of the typical CD player. In some cases the source impedance of a preamp could be far smaller than that for a CD player (or MP3 player, or tuner, or other line level output). I will no longer support the idea that "no preamp" is the best preamp--in all cases. It depends. In any case, for now I am stuck with using the ugliest preamp I have ever seen because it sounds so much better than no preamp Smile

    frank

    Posts : 95
    Join date : 2011-02-14
    Location : Pacific Northwest

    Re: Maybe a preamp is a good idea after all...

    Post by frank on Mon Mar 28, 2011 12:33 am

    Hi j,
    Yes from what I've read preamps often act as impedance matching devices. I haven't experienced this myself, but can believe it to be true.

    'Frank

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