Dkvtechlab,
You're asking some very good questions directed toward finding the source of the DKV hum coming out the speakers and when used with an external amp. Your questions are well placed and your background info sounds correct.
However, in this case the source of the problem is obvious. The DKV hum is audibly present in the speaker with the DKV operating as a stand-alone instrument. Only one electronic device plugged in -- no possibility for ground loops. The problem is a lack of proper design in the instrument itself. It can only get worse when connected to external devices such as an amp. Your comments re grounding and making sure to use the same outlet are right on, and essential to keep the problem from getting worse.
The other problem is the choice of signal levels at the aux output -- they're low level and designed for use with a preamp. In that environment the presence of line frequency hum on these outputs makes that a very poor choice. For use with the kind of consumer electronics that most of us would use with these outputs, that was just a very poor design choice. Unfortunately we're stuck with it.
Jerry Dutcher
-----Original Message-----
From: dkvtech1ab
Sent: Nov 28, 2004 3:42 AM
To: disklavier@yahoogroups.com
Subject: [disklavier] Re: hum from amplifier
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" 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
> >
> >
> >
>
>
> To Post a message to the group, send it to: disklavier@Y...
>
> To Post a private message to Todd Muncy, the group's founder and
moderator, send it to:
> disklavier-owner@Y...
>
> To reach our group's web site go to:
> http://Yahoogroups.com/group/disklavier
>
> Todd's family web site was completely updated 012/22/03. It
contains some fun disklavier content and links to midi sites among
many other things, The url is:
> http://MuncyFamily.com
>
> THINKING OF LEAVING THE GROUP?
> If you are thinking of unsubcribing because you are getting too
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>
>
>
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>
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Service.
To Post a message to the group, send it to: disklavier@...
To Post a private message to Todd Muncy, the group's founder and moderator, send it to:
disklavier-owner@...
To reach our group's web site go to:
http://Yahoogroups.com/group/disklavier
Todd's family web site was completely updated 012/22/03. It contains some fun disklavier content and links to midi sites among many other things, The url is:
http://MuncyFamily.com
THINKING OF LEAVING THE GROUP?
If you are thinking of unsubcribing because you are getting too much mail, go the the web site and change your email delivery option instead. That will fix the problem, while maintaining your access to the group. If you insist on leaving us completely send a blank email to:
disklavier-unsubscribe@...
Know someone who wants to join? Have them send a blank email to:
disklavier-subscribe@...m or give them this link:
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-----Original Message-----
From: dkvtech1ab
Sent: Nov 28, 2004 3:42 AM
To: disklavier@yahoogroups.com
Subject: [disklavier] Re: hum from amplifier
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" 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
> >
> >
> >
>
>
> To Post a message to the group, send it to: disklavier@Y...
>
> To Post a private message to Todd Muncy, the group's founder and
moderator, send it to:
> disklavier-owner@Y...
>
> To reach our group's web site go to:
> http://Yahoogroups.com/group/disklavier
>
> Todd's family web site was completely updated 012/22/03. It
contains some fun disklavier content and links to midi sites among
many other things, The url is:
> http://MuncyFamily.com
>
> THINKING OF LEAVING THE GROUP?
> If you are thinking of unsubcribing because you are getting too
much mail, go the the web site and change your email delivery option
instead. That will fix the problem, while maintaining your access to
the group. If you insist on leaving us completely send a blank email to:
> disklavier-unsubscribe@y...
>
> Know someone who wants to join? Have them send a blank email to:
> disklavier-subscribe@e... or give them this link:
> http://Yahoogroups.com/group/disklavier/join
>
>
>
> Yahoo! Groups Sponsor
> ADVERTISEMENT
>
>
>
>
>
>
------------------------------------------------------------------------------
> Yahoo! Groups Links
>
> a.. To visit your group on the web, go to:
> http://groups.yahoo.com/group/disklavier/
>
> b.. To unsubscribe from this group, send an email to:
> disklavier-unsubscribe@yahoogroups.com
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service.
To Post a message to the group, send it to: disklavier@...
To Post a private message to Todd Muncy, the group's founder and moderator, send it to:
disklavier-owner@...
To reach our group's web site go to:
http://Yahoogroups.com/group/disklavier
Todd's family web site was completely updated 012/22/03. It contains some fun disklavier content and links to midi sites among many other things, The url is:
http://MuncyFamily.com
THINKING OF LEAVING THE GROUP?
If you are thinking of unsubcribing because you are getting too much mail, go the the web site and change your email delivery option instead. That will fix the problem, while maintaining your access to the group. If you insist on leaving us completely send a blank email to:
disklavier-unsubscribe@...
Know someone who wants to join? Have them send a blank email to:
disklavier-subscribe@...m or give them this link:
http://Yahoogroups.com/group/disklavier/join
Yahoo! Groups Links
- To visit your group on the web, go to:
http://groups.yahoo.com/group/disklavier/
- To unsubscribe from this group, send an email to:
disklavier-unsubscribe@yahoogroups.com
- Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.