Conference napalm::commusic_v1

    Just to get things a little more into perspective...
    
    A bottom of the range CLAVINOVA is about �900-�1000 here in the
    UK. This CASIO CPS700 (which I understand to be new on the market)
    cost us �500.
    
    My own (unqualified) views are that apart from the 'blemish' referred
    to in .0 it is excellent value for money.
    
    Still, what about this blemish?
    
    Richard

    The piano sounds in your unit are probably created by digital samples
    of real piano sounds.  Unless the original note frequency, sample
    rate, processing circuitry, and DAC (digital-to-analog converter) 
    are carefully matched, 'aliasing' may occur.  Anyone (Bill Y?) wanna 
    cover the math involved ?
    
    Aliasing is (are?) high-frequency overtones that are generated 
    mathematically by said mismatched components.  Unfortunately, the 
    overtones are not related harmonically to the base sample frequency, 
    thus sounding like an 'annoying phasing/buzzing' sound.
    
>Question is, is this normal on cheaper keyboards or is there something
>wrong? Is it a bug or a feature! Do cheaper keyboards have higher
>signal/noise ratios? 
    
    It's not a signal/noise issue.  Even the best DAC money can buy
    will send alias frequencies out if the circuitry creates
    it.  On lower-priced samplers, aliasing can be a problem.  Some 
    units use special anti-aliasing filters. ALL samplers, no matter 
    how expensive, will generate aliasing sounds if a sample is 
    transposed too far from its original frequency.
    
    Low-priced SYNTHESIZERS will not generate alias frequencies.. 
    depending on the sound generation method used, they have their own
    sets of problems..
    
    karl moeller, in warm, sunny Tucson, Arizona, USA
    

    I doubt this is aliasing as much as it quantization noise.  Aliasing
    would be independent of signal level; i.e., the mismatch between
    sampling frequency and signal bandwidth would occur or not regardless
    of signal level.  Quantization noise, however, increases relative
    to the signal as the signal level decreases.  I.e., the difference between
    one bit's worth of difference is quite a bit larger (oops, excuse
    me) for a 16 bit signal at a value of 0000000000000010 than it is at
    a value of 01111111111111110.  This "noise" shows up as quite
    pronounced distortion; it is one of the more curious features of
    digital audio systems that below overload (i.e., running out of
    bits), distortion decreases with increasing signal level, contrary
    to most analog systems, where distortion increases with increasing
    signal level.
    
    Cheaper keyboards *do* have poorer S/N (or distortion) specs for
    precisely this reason; they have fewer bits of converter, hyence
    higher relative noise.
    
    A well designed product (regardless of its cost to manufacture)
    should not exhibit aliasing; for it to do so would mean that the
    designer's left hand didn't know (or ignored) what the right hand
    was doing.
    
    len.
    

    Well, thanks for the input. It would appear then that this IS probably
    a design issue rather than a bug. Since I have seen nothing to compete
    pricewise with this instrument here in the UK I guess there's not
    much I can do. I will however get my hands on another CPS700 in
    a shop and see if it displays the same characteristics.
    
    Thanks
    Richard

    Moved by moderator - there's no sense in having another keyboard with
    umpteen different topics, and LINE OUTs have been covered in earlier
    topics (DIR/TITLE=blah).  Thanks for your consideration. 


--------------------------------------------------------------------------------
Note 1814.0                   LINE OUT information                       1 reply
LARVAE::BRIGGS "They use computers don't they?"      18 lines  15-DEC-1988 04:39
--------------------------------------------------------------------------------

    I suspect this is a general question rather than one relating to
    the particular keyboard I have (CASIO CPS700).
    
    It has a LINE OUT jack socket. The good book says its for connection
    of the instrument to external audio equipment or LOUDSPEAKERS. Surely
    not? Surely its either a feed into a hi fi or its just for connecting
    a single speaker. Surely it can't be both.
    
    Having got the above straight. What about the following questions...
    
    Would it be a straight jack or a stereo jack? The instrument hasn't
    got stereo chorus built in. Also, where would you feed it into a
    home Hi-fi? Auxiliary input? Recorder input?
    
    Regards,
    Richard
    Basingstoke, UK
    
--------------------------------------------------------------------------------
Note 1814.1                   LINE OUT information                        1 of 1
ALEX::CONN "Alex Conn, ZKO"                          29 lines  15-DEC-1988 10:00
                         -< Connection to home units >-
--------------------------------------------------------------------------------

    Normally LINE OUT is for connection to a (home) audio amplifier,
    integrated amplifier, receiver, etc.   In this context, "loudspeaker"
    probably refers to speakers used in live performances (that generally
    have built-in amplifiers). 

    I have not seen the 700 in person, but the stereo CASIO units I have
    looked at have two RCA type jacks for stereo LINE OUT.  These jacks are
    for connection to any standard input (AUX or LINE IN or REC IN) of a
    preamp,  receiver, or for connection directly to an amplifier.  Put
    another way, avoid MIC or PHONO inputs (MIC and PHONO generally have
    too much amplification and special equalization circuits that you want
    to avoid). You can also use the headphone output if you'd like.  You
    need a cable with a stereo �" plug on one end and twin RCA plugs on the
    other.  Connect the headphone outlet to AUX, LINE  IN, etc. on any home
    receiver or integrated amplifier. 

    Hope this helps, 

Alex

    I concur with Len. Sounds like (no pun) quant. noise.
    And also, aliasing would be present thruout the duration
    of the 'note', but this noise is only present on the
    decay......
    
    Good call Len.
    
    rr