Disklavier

Hello everyone

 Seems to me there are 2 different issues here. 

1- J. Young's Disklavier Hum is being emmited by the AMP unit and not
the speakers.


 What I'd like to know is;

 A- is the Hum heard at the speakers always there?
 B- Does it increase when the Treble knob is turned up?
 C- Is the HUM very loud when connected to an external sound system
even if the voulume in the amp-Disklavier- is turned down completely.
 D-Have you tried a different AC outlet even if it takes a 50 foot AC
cord?
 
 My 2 cents...Most electronic audio instruments will emmit hum when
certain criteria is encountered. Hum will be more noticeable when 2
electronic sound systems are put together. 
 
Possible reasons

 1- UL requires grounding and threfore, it will be a path for most
source of noises. When 2 systems are put together, their wireing has
resistance thus, creating at X and Y points a potential difference
that by it's nature developes a voltage across this resistance. What
you get is noise from the difference.

 2- Noise can be developed someplace else in the house specially when
Blenders, Refrigerators, just about anything with a motor in the same
AC Line will cause Inductive Reactance.

 To test if the Disklavier's noise is being generated some place else
in the AC line.

A- Use a Ground puller-for testing purposes only, remove puller after
finding the desired information-and listen to the speakers with the EQ
BASS and TREBLE set to 12 O'Clock. If the Noise is gone or greatly
diminished then, part or most of that noise is at the AC level.

Possible solution..Use a dedicated AC line or an AC Conditioner.

B-If the noise does not decrease and instead it may increase then, it
could be a ripple factor at the power supply.

Possible solution..New power supply
 
 Most of the time, the problem is at the  AC Line level.

 I hope this helps!!

 dkvtech1ab

 

--- In disklavier@yahoogroups.com, "Jerry Dutcher" <gldutcher@e...> wrote:
> When I got my new MkIII Disklavier last year I noticed the same
thing.  I have a very audible 60 Hz hum coming out my DKV speakers --
not outrageous, but definitely audible.  When I connected the aux
outputs to an amplifier it WAS outrageous.  The aux outputs are quite
low level -- not at all full line-level signals.  Thus a modest amount
of 60 Hz hum on these lines will be amplified disproportionately.  I
spoke to Bill Brandom at Yamaha -- he was familiar with the problem
and recommended the use of a mixer/preamp with the aux outputs.  I
picked up such a unit at my local Guitar Center outlet, and it brought
the hum down to a tolerable level.  I still hear the hum very clearly,
but frankly most casual listeners don't notice it.
> 
> My conclusion is that while Yamaha did a fantastic engineering job
on the basic DKV instrument, the electronics design did not receive
the same degree of attention.  Yamaha has in their corporation a world
class audio electronics arm, and the design techniques for minimizing
and eliminating line frequency hum are well understood.  It is beyond
my understanding why they did not apply some of this knowledge to the
DKV electronics design.  Proper grounding, filtering and shielding
throughout could eliminate this problem, but it would take an
electronics redesign to accomplish it.  
> 
> Jerry Dutcher
> 
> ----- Original Message ----- 
>   From: J D 
>   To: disklavier@yahoogroups.com 
>   Sent: Tuesday, November 23, 2004 5:05 PM
>   Subject: RE: [disklavier] hum from amplifier
> 
> 
>   I have a similar problem with my DC7A.  It is more noticeable when
I have recorded from the auxiliary outputs.  I will be interested in
knowing what you guys suggest.
> 
>   Thanks,
> 
>   John W
> 
> 
> 
> 
> 
>   >I have a new DC1A with an intermittent problem:  There is 
> 
>   >occasionally a hum that comes from the amplifier - perhaps the power 
>   >supply.  The noise does not come through the speakers but comes 
>   >directly from the amplifier box.  Has anyone else had this problem? 
>   >Unfortunately, the problem disappeared when my tech arrived, but of 
>   >course, reappeared after he left.  Any solutions? 
>   > 
>   >Thanks. 
>   > 
>   >J. Young 
>   > 
>   > 
>   > 
> 
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