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#1426341 - 04/29/10 05:15 AM Roland HP 305 hum
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
Hi, I'm new to digital pianos since I've only played acoustic pianos in the past. Now I got myself a HP 305 and am quite happy with it.

But I noticed that when it's quiet in the room in the evening that the piano when turned on is humming. Basically when you turn it on it starts to emit a silent hum. When playing it's obviously not audible because of the piano sound itself, but when not played there is definitely a hum.

Is this normal for a digital piano or might this be a defect?

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#1426351 - 04/29/10 05:53 AM Re: Roland HP 305 hum [Re: goatfreed]
paddy1nz Offline
Full Member

Registered: 04/17/10
Posts: 32
My Technics PR604 used to do that. It was SOOO loud to me, I had to use headphones all the time, although no one else ever seemed to be able to notice it. I hated it (though loved the Technics itself). Just getting back into DPs (have been out for a few years), so don't know your instrument - has it got an LCD screen? It could be the screen emitting that noise.

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#1426359 - 04/29/10 07:07 AM Re: Roland HP 305 hum [Re: paddy1nz]
Bob Newbie Offline
1000 Post Club Member

Registered: 09/02/06
Posts: 1555
How's the house wiring? could be the outlet's not properly grounded..

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#1426394 - 04/29/10 09:01 AM Re: Roland HP 305 hum [Re: Bob Newbie]
jmmec Offline
Full Member

Registered: 02/02/10
Posts: 86
Loc: New Mexico (yes, USA!)
Hmmm... I do not have this problem on an HP-307 that I have.

Regards
_________________________
Roland HP-307
Roland Quad-Capture

https://vimeo.com/58278342

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#1426409 - 04/29/10 09:30 AM Re: Roland HP 305 hum [Re: jmmec]
dewster Offline
4000 Post Club Member

Registered: 12/07/09
Posts: 4366
Loc: Northern NJ
Does the level of the hum change when you change the volume, or is it constant?
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THE RD-700NX Thread!
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#1426419 - 04/29/10 09:50 AM Re: Roland HP 305 hum [Re: dewster]
hpeterh Offline
500 Post Club Member

Registered: 01/26/10
Posts: 824
Loc: Germany
Had this with my Kawai CP136. Finally I found, it was not the piano, it was the piano lamp that I had on top of it.
If it has a transformer it can make noise also when switched off.

Peter
_________________________
1929 Galaxy Blüthner Baby Grand
acer aspire m3300 AMD Phenom II X6


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#1426437 - 04/29/10 10:28 AM Re: Roland HP 305 hum [Re: hpeterh]
bkmz Offline
Full Member

Registered: 11/19/09
Posts: 142
Loc: Belarus
I had the same problem with my CLP330. But the hum was heard only when setting volume to max (which is too loud to play in room).
_________________________
ex-Yamaha CLP 330

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#1426506 - 04/29/10 01:15 PM Re: Roland HP 305 hum [Re: bkmz]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
The hum is constant independent of the volume setting. Really odd, couldn't hear it in the store obviously since there it's never 100% quiet. Also tried plugging it into the wall socket as the sole device without a multiplug - still humming. Any 305 owner who can comment on this?


Edited by goatfreed (04/29/10 01:16 PM)

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#1426507 - 04/29/10 01:15 PM Re: Roland HP 305 hum [Re: dewster]
spanishbuddha Offline
2000 Post Club Member

Registered: 11/08/09
Posts: 2470
Loc: UK
Originally Posted By: dewster
Does the level of the hum change when you change the volume, or is it constant?

Similar question, can you still hear it with headphones plugged in - from across the room with headphones off (your ears), and also in the headphones? So the question is it coming from the sound system or somewhere else?

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#1426520 - 04/29/10 01:34 PM Re: Roland HP 305 hum [Re: spanishbuddha]
Stephen Lacefield Offline
Full Member

Registered: 11/29/06
Posts: 195
Loc: St. Louis, MO
I think the Rolands hum because they don't know the words...
_________________________
Representing Shigeru Kawai, Kawai, Hailun, Pearl River, Kawai Digital Pianos, Samick Digitals, Roland Digitals, & Lowrey Organs
St. Louis Metro Area
www.lacefieldmusic.com
find us on Facebook: http://www.facebook.com/lacefieldmusic

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#1426560 - 04/29/10 02:55 PM Re: Roland HP 305 hum [Re: Stephen Lacefield]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
The hum is there when the headphones are plugged in, but it's not audible in the headphones (the piano itself is humming independent of headphones plugged in or not). It is not audible across the room (it's not that loud). Basically it fades afer 3 metres.

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#1426567 - 04/29/10 03:05 PM Re: Roland HP 305 hum [Re: goatfreed]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
After some research I think it is transformator hum which is 100hz since here in Austria we have 50hz AC. Also it sounds exactly like this (http://www.youtube.com/watch?v=4Ufa4bXViA4). Unfortunately it seems that this a physical phenomenon, so I assume all digital pianos should have this problem more or less except if the manufacturer somehow isolates the transformator.

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#1426586 - 04/29/10 03:35 PM Re: Roland HP 305 hum [Re: goatfreed]
ChrisA Offline
3000 Post Club Member

Registered: 12/28/08
Posts: 3841
Loc: Redondo Beach, California
Originally Posted By: goatfreed

But I noticed that when it's quiet in the room in the evening that the piano when turned on is humming.


Any hum should be at a level that is un-detectable by human hearing - in other words you should never hear it underany condidtion.

Somehow noise from the AC main power line is getting into the piano and being amplified. Actaully it takes a bit of enginerring skill to design an audio system that does not hum. You might notice that cheap, low cost audio equipment will hum. The piano shouldn't. Either the unit is defective, something wriog inside the power supply or yu have a BIG source of noise in your house, one strong enough to get past all the tricks the engineers use to keep it out.

One way to diagnose this is to turn off everything else in the house. And I mean everytrhing, TVs lights and even unplug every wall transformer, cell phone charger Note that to turn some many devices (TVs, stereos, refrigerators) off you must unplug them.

If that does not solve the hum then it is something inside the piano.

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#1426595 - 04/29/10 03:42 PM Re: Roland HP 305 hum [Re: goatfreed]
ChrisA Offline
3000 Post Club Member

Registered: 12/28/08
Posts: 3841
Loc: Redondo Beach, California
Originally Posted By: goatfreed
After some research I think it is transformator hum which is 100hz since here in Austria we have 50hz AC. Also it sounds exactly like this (http://www.youtube.com/watch?v=4Ufa4bXViA4). Unfortunately it seems that this a physical phenomenon, so I assume all digital pianos should have this problem more or less except if the manufacturer somehow isolates the transformator.


Typically transformers are "varnished" After they are made they are placed in vacuum to remove the air from between the coils of wire then dunked in varnish then baked. The goal is to make them silent and not vibrate. What you've got is either a defective transformers or a cheaply made one. It should not make any noise. Yes isolating it by mounting it on rubber might help but they should not vibrate.

Many manufacturers do isolate the transformaer. My Yamaha DP uses an external transformer that connects to the piano with a long DC power cable.

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#1426611 - 04/29/10 04:13 PM Re: Roland HP 305 hum [Re: ChrisA]
dewster Offline
4000 Post Club Member

Registered: 12/07/09
Posts: 4366
Loc: Northern NJ
So you only hear it when the piano is actually turned on, correct?

Is the power connector two conductor (as it shows in the HP-307 US owner's manual) or three conductor (w/ ground)?
_________________________
The DPBSD Project!
THE RD-700NX Thread!
DPs Exposed! (nekid pichures!)

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#1426689 - 04/29/10 05:33 PM Re: Roland HP 305 hum [Re: ChrisA]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3900
Loc: North Carolina
Originally Posted By: ChrisA
Any hum should be at a level that is un-detectable by human hearing. ... Somehow noise from the AC main power line is getting into the piano and being amplified ... Either the unit is defective, something wriog inside the power supply
Quite right. If a nearby noise source cannot be identified, then I'm guess the piano is defective. If so, let it be Roland's warranty issue rather that your own headache. Get it fixed.

As for transformers ... do these pianos even have them anymore. Transformers are so 1950's. Most equipment these days use switching power supplies. No hum. (A very high pitch squeal, maybe. A dog might hear it. But no hum at all.)

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#1426730 - 04/29/10 06:58 PM Re: Roland HP 305 hum [Re: goatfreed]
bkmz Offline
Full Member

Registered: 11/19/09
Posts: 142
Loc: Belarus
Originally Posted By: goatfreed
After some research I think it is transformator hum which is 100hz since here in Austria we have 50hz AC. Also it sounds exactly like this (http://www.youtube.com/watch?v=4Ufa4bXViA4). Unfortunately it seems that this a physical phenomenon, so I assume all digital pianos should have this problem more or less except if the manufacturer somehow isolates the transformator.


Oh, I was wrong. That's not hum from CLP330. It was rather "white noise".
_________________________
ex-Yamaha CLP 330

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#1426741 - 04/29/10 07:16 PM Re: Roland HP 305 hum [Re: MacMacMac]
NikkiPiano Offline
Full Member

Registered: 02/05/10
Posts: 172
Loc: Hertfordshire, UK
Originally Posted By: MacMacMac
As for transformers ... do these pianos even have them anymore. Transformers are so 1950's. Most equipment these days use switching power supplies. No hum. (A very high pitch squeal, maybe. A dog might hear it. But no hum at all.)


Do you think this could be to do with reliability and cost? For example, I find that the new electronic (switching) ballasts for fluorescent lighting don't seem to last as long as the less expensive magnetic ballasts.

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#1426826 - 04/29/10 11:02 PM Re: Roland HP 305 hum [Re: NikkiPiano]
MacMacMac Offline
3000 Post Club Member

Registered: 09/24/09
Posts: 3900
Loc: North Carolina
Originally Posted By: NikkiPiano
Originally Posted By: MacMacMac
As for transformers ... do these pianos even have them anymore. Transformers are so 1950's. Most equipment these days use switching power supplies. No hum. (A very high pitch squeal, maybe. A dog might hear it. But no hum at all.)


Do you think this could be to do with reliability and cost? For example, I find that the new electronic (switching) ballasts for fluorescent lighting don't seem to last as long as the less expensive magnetic ballasts.
I can't speak about that kind of equipment. But for consumer electronics ... the use of switching power supplies cuts the size and weight (by eliminating the transformer), and it improves efficiency.

With a regular transformer-based linear power supply, about 5% of the device's total power consumption gets wasted as heat in the power transformer. That energy loss is largely eliminated when using a switching power supply.

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#1426842 - 04/29/10 11:36 PM Re: Roland HP 305 hum [Re: MacMacMac]
ChrisA Offline
3000 Post Club Member

Registered: 12/28/08
Posts: 3841
Loc: Redondo Beach, California

Quote:
As for transformers ... do these pianos even have them anymore. Transformers are so 1950's. Most equipment these days use switching power supplies. No hum. (A very high pitch squeal, maybe. A dog might hear it. But no hum at all.)


All power supplies have transformers. The switching supplies use smaller transformers working at higher frequency but still it's a transformer

Most high end audio equipment still uses linear power supplies. Most of the cheap wall wort supplies are linear too.

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#1426916 - 04/30/10 03:07 AM Re: Roland HP 305 hum [Re: ChrisA]
hpeterh Offline
500 Post Club Member

Registered: 01/26/10
Posts: 824
Loc: Germany
My CP136 has a very large and solid transformer inside.

Switching power supplys where not used in quality audio devices for a long time, because they all where a strong source for interference.
Only in newer time it was possible to use them, because it was possible to rise the switching frequency to 100kHz and more, using modern semiconductors and coils.

But even today linear supplys with transformers are in use.
There is a physical phenomenon, named "magnetostriction" that causes every transformer to produce some hum, regardles how solid it is build. Normally this is not audible, but if the transformer has direct mechanical connection to a resonance board, wood or else, it can become audible.
_________________________
1929 Galaxy Blüthner Baby Grand
acer aspire m3300 AMD Phenom II X6


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#1426941 - 04/30/10 04:26 AM Re: Roland HP 305 hum [Re: hpeterh]
Kawai James Offline
9000 Post Club Member

Registered: 09/06/07
Posts: 9680
Loc: Hamamatsu, Japan
Don't worry Stephen, it got a laugh at this end. wink

Cheers,
James
x
_________________________
Employed by Kawai Japan, however the opinions I express are my own.
Nord Electro 3 fan & occasional rare groove player.

"Richard, none of us could forget you have a CLP-990." - EssBrace, 2014

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#1427016 - 04/30/10 09:13 AM Re: Roland HP 305 hum [Re: Kawai James]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
Thanks for all the feedback. It's a shame that you'll never notice this in a shop, but only once you got the piano and turn it on in the evening.

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#1427068 - 04/30/10 11:19 AM Re: Roland HP 305 hum [Re: jmmec]
Mr Romance Offline
Full Member

Registered: 10/11/09
Posts: 102
Loc: USA
If you not mind me asking, how much did you pay for your HP 307?
_________________________
Kawai MP8II, Logic Studio 9, Alicia's Keys, AKG 240.

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#1427163 - 04/30/10 01:33 PM Re: Roland HP 305 hum [Re: goatfreed]
spanishbuddha Offline
2000 Post Club Member

Registered: 11/08/09
Posts: 2470
Loc: UK
Originally Posted By: goatfreed
Thanks for all the feedback. It's a shame that you'll never notice this in a shop, but only once you got the piano and turn it on in the evening.

Can you tell us where it's coming from? Thanks. It sounds like you've accepted it as a, errr,,, 'design' limitation? I can't hear any hum from my cheaper DP in a quiet room.

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#1427176 - 04/30/10 01:47 PM Re: Roland HP 305 hum [Re: spanishbuddha]
hpeterh Offline
500 Post Club Member

Registered: 01/26/10
Posts: 824
Loc: Germany
I know about a hum in Yamahas CVP509. Some customers hear it, others do not.
If a customer complains, then Yamaha sends a technician. He/she will cut a trace on the PCB and this will fix the problem.

That said, doesnt mean that it is a similar problem. It could be as simple as a loose screw at the transformer that has to be tightened.

If it disturbs you, ask the dealer, maybe he has technicians that know about it or ask at Rolands service.
If you are unsure about it, test if other people hear it.
/
Peter
_________________________
1929 Galaxy Blüthner Baby Grand
acer aspire m3300 AMD Phenom II X6


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#1427192 - 04/30/10 02:04 PM Re: Roland HP 305 hum [Re: hpeterh]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
Yes, other people hear it as well. The hum comes from the slits on the left and right side above the keyboard. I assume they are speakers? I will go to the dealer again once I have time to do so and see if the piano they have on display also hums. I didn't pay attention at all since in the shop it obviously is not dead silent like at home in the night.

@Mr Romance: I got a 305 and paid €2000 here in Vienna.

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#1427229 - 04/30/10 03:02 PM Re: Roland HP 305 hum [Re: goatfreed]
jmmec Offline
Full Member

Registered: 02/02/10
Posts: 86
Loc: New Mexico (yes, USA!)
Yes, those two slits (at the top of the piano) are where two 5cm speakers are located (one on each side).
_________________________
Roland HP-307
Roland Quad-Capture

https://vimeo.com/58278342

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#1428456 - 05/02/10 05:15 PM Re: Roland HP 305 hum [Re: jmmec]
goatfreed Offline
Full Member

Registered: 04/28/10
Posts: 24
the power connector has no ground. so can the hum still be a ground loop? I am a total newbie when it comes to audio equipment, but I read that ground loops are the main source for hum in audio equipment.

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#1428466 - 05/02/10 05:29 PM Re: Roland HP 305 hum [Re: goatfreed]
spanishbuddha Offline
2000 Post Club Member

Registered: 11/08/09
Posts: 2470
Loc: UK
Originally Posted By: goatfreed
the power connector has no ground. so can the hum still be a ground loop? I am a total newbie when it comes to audio equipment, but I read that ground loops are the main source for hum in audio equipment.

Do you have anything else connected? PC, amp, headphone, etc.

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