Conference hips::uk_audioo

    Could be a 'feature' of your receiver, although I don't know NAD
    to exhibit this kind of thing. I also thought the protection has 
    a slight delay just to prevent these switch-on effects. Please 
    check if it depends on
    - volume control set to 0?
    - source selected?
    Also, does that type have a 'protection' indicator on the frontpanel?
    Does it light when switching on or off? And if it does, does the
    sound come at the moment you switch on or at the moment the indicator
    goes off? Last question (for this note at least), is it a 'bwoph'
    or a 'click' kind of sound?
    
                                                     - Rik -
    
    PS.
    >when I first power on the receiver. I'm a hi-fi illiterate
    >but enjoy good sound [and, believe it or not, music :-)]. The
    >system (I hesitate to say, given the exalted company in which
                ^^^^^^^^^^^^^^
    
    No need to talk yourself down! No matter what others say, the ears
    listening are yours, and if they're pleased, you system is OK. It
    might be that your quality demand grows (mine still does). If it
    does, you can find valuable advice here to do the best things within
    your budget, but don't let it dictate you. The system is the means,
    not the target (although I know a few people who listen to GEAR,
    not to MUSIC....).
    
    PPS. I noticed the smiley

    Don't feel apologetic for your system! It looks well matched, and if it
    gives you pleasure, nothing else counts much.
    
    Do you only get the noise on power up with particular sources (CD,
    phono, etc) selected, or doesn't it make any difference? Is it
    independent of volume setting?
    
    If the system's working OK otherwise, forget it. Relax and enjoy your
    music.
    
    Dave

    Thanks for the suggestions; I'll try volume set at zero. It doesn't
    seem to matter which source is selected at power on. The 'problem'
    has been there for yonks and doesn't cause me loss of sleep; it's
    just a case of slight irritation.
    
>        Also, does that type have a 'protection' indicator on the frontpanel?
>    Does it light when switching on or off? And if it does, does the
>    sound come at the moment you switch on or at the moment the indicator
>    goes off? Last question (for this note at least), is it a 'bwoph'
>    or a 'click' kind of sound?
 
	No, there is no 'protection' indicator on the receiver. Yes,
    it is a 'bb-woph'
    
    Pat    

    I'd just like to reiterate some advice given to me....
    
    1. Before turning on your amp, set volume to zero.
    2. On some Amps, like low end Denon's, the protection is a bit funny
    (know Nothing about electronic's) and that when switching on and
    swithing sources, that a 20 second gap ought be left before you
    do anything.
    3. Nad's have this funny power clipping feature. May be a genius
    like Mr Sallitt might be able to tell you if this does anything
    on power up.
    4. My Rotel does the same.
    5. your system is probably better balanced than mine and probably
    sounds better.... I still class myself as a sort of Potential or
    Trainee Audiophile.....
    
    Juju
    xxxx
    

    re .4...
    
    "    3. Nad's have this funny power clipping feature. May be a genius
    like Mr Sallitt might be able to tell you if this does anything
    on power up."
    
    No, it doesn't do anything on power up. It only does anything under
    dynamic conditions when playing very loud.
    
    Also, in terms of notesfiles hifi genii, I regard such as Walt Clark,
    Bob Sanders, and Jim Roth and some others from DSSDEV::AUDIO as the real
    experts. Although I have an electronics background, my hifi knowledge
    is mainly by association; compared to the aforementioned, I am but a
    mere dabbler on theoretical issues.
    
    Dave

>    Do you only get the noise on power up with particular sources (CD,
>    phono, etc) selected, or doesn't it make any difference? Is it
>    independent of volume setting?
 
    The noise is source and volume setting independant.
       
>    If the system's working OK otherwise, forget it. Relax and enjoy your
>    music.
 
    I'll take your advice; thanks
    
    Pat

    Well, it seems that
    a) yes there is something not really right
    b) no you can't do much about it.
    
    It's in the design. All amps have certain operational values, DC
    level, bias currents and so. It needs to be stable, so any drift
    away from these values must be counteracted SLOWLY. Too fast and
    you won't be able to amplify low frequencies (the signal which needs
    to be amplified is acted on in the same way as the drift which needs
    to be reversed). Too slow and the amp may be operating at values
    which are unacceptable for longer periods.
    Now if you switch the thing on, its internal currents and such
    go up from 0 (no supply - no current) to working level in say a
    second or two. During this time there may be fluctuations in the
    output signal as the amp hasn't yet reached its stable point. This
    you hear as a 'dounk' or 'bwoph' from your speakers. The only way
    to avoid this is by switching off the speakers until the amp is
    stable, or else by very careful design. The first way is clearly
    more attractive to the buyer.... 
    
    I hope I haven't been talking Chinese to you, and don't let it spoil
    your listening. At the level you're hearing it, the effect doesn't
    hurt anything.
    
                                                   - Rik -

    Thanks, Rik, sounds logical. I'll get back to listening to the music!
    
    Pat