Piano World Home Page Forums Our Most Popular Forums Digital Pianos - Electronic Pianos - Synths & Keyboards Kawai CA 95 makes an annoying electric hum sound

So spanishbuddha had it right ten days ago:You'll need a replacement transformer (or a replacement piano).

I hope replacing the transformer would do the trick. better than exchanging such a big bulky thing as a whole piano cabinet (+ boxes and everything else). Good luck !

What happened to your problem ?is it solved ?

Thanks for asking. This afternoon two Kawai Technicians from Germany visited my home. They acknowledged that this kind of electric hum of the transformator should not be there. The piano has to be quiet. Then they replaced the transformator for a new one. But this did not solved the problem. There was still an electric hum, to loud to be considered 'normal'. It seems the problem is caused by placing the transformator directly on the wooden bottom. I consider this as a flaw in the construction.
They will discuss this problem internally with Kawai. One of the technicians said that maybe it is an option that they try a new CA 95 in a absolutely quiet room. If this piano does not make the electric humming, it can be replaced with mine. Anyway next week he will make a telephone call to inform me of a possible solution. To be continued.....

Any updates on your humming issue? I think I have a similar problem on my CA95, but this is rather a rattling noise when the volumn is above 1/2, especially 3/4. The key that makes the most vibrating/rattling sound is the 3rd F key counting from the left hand side. This thing bothers me a lot. I don't think it's normal because my other DP doesn't have this problem even when you max the volumn. What should I do?

Kenboi2, if you have any concerns, please contact the dealer whom the CA95 was purchased, and/or the distributor in your region (e.g. Kawai UK).

Kind regards,
James
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Hi Kenboi2 (and others from PW)! I, too, recently bought and received Kawai CA95 (I plan to write a short review, I am mostly very happy). But this thread and your post in particular really caught my attention, because:

1. My CA95 also makes audible electric humming noise after being turned on. It is not really disturbing during playing but when silent it is very clearly audible. In my opinion it's power source/transformator.

2. I spent several hours this weekend in search for audible resonance coming from the piano when playing F3 - rattling sound exactly as you describe it. There may be more than one "points of origin" but I strongly suspect the area around the power supply causes (or contributes to) the resonance/rattling. I am not very good and finding sound sources but it seemed to me the rattling (or part of it) comes from that place and when I held the power supply (it is in a special box kind of protruding from the bottom of the piano) firmly in my hand, the rattling diminished considerably.

3. There is another (perhaps related?) issue I have with my CA95 and I would like to hear your opinions on this one. Some keys (the F3 by far most of all) when played with the sustain pedal pressed make "more sound" that others. I do not mean only louder but kind of "more overwhelming", it is difficult to describe but it's like I am in the middle of a bubble made of one tone, like there is a piano tone with an envelope of loundess (if you now discard me as lunatic I can't blame you). Unfortunately I have the piano in a room with very poor acoustics (major reason why I have digital in the first place, to play with headphones) but it usually manifests itself as individual tones being louder, more "piercing" to the ears, not this overall "loudness bubble" enveloping a clear tone, but I don't know. It is present (to lesser degree) even in headphones, but it is more apparent when amplified by speakers, combined with the aforementioned rattling noise (and possibly poor room acoustics) - it then makes the overall experience quite unpleasant (especially as it is only one or two keys).

The key which behaves by far worst in this aspect is the discussed F3. I decided to record a little test and upload for your examination (link below). Let me know if you think this "sounds normal" or it's strange.

Test description:

1st half: I play F, then press sustain pedal. After pressing the pedal, the sound is amplified and kind of modified. I do this 3 times. Then I do 3 times the same thing with A (a third higher) - no similar thing happens. Then the infamous F again, 3 times.

2nd half: I press the sustain pedal and pres F repeatedly, the sound snowballs and becomes unpleasantly loud and "like in a bubble". I do the same thing with A (approximately similar velocity, as perceived), it is much quieter and without the unpleasant "envelope". Then F again. This recording is actually not really convincing, but when played on the piano it's crystal clear.

Link: https://soundcloud.com/hookxs/sets/f3-pedal.

I believe there is some error the sympathetic resonance computation, because this is not how accoustic piano behaves and even CA95 does this for a few keys (mainly F3). If so, it could and should be addressed by firmware update. Let me know your opinion. I am sorry for the lengthy and possibly comfusing explanation, describing sounds in foreign language is like trying to draw what apple tastes like. I'll be more than happy to clarify and case anyone is interested.

Hi Hookxs,

Thank you for your comprehensive review. I am glad there're more owners of Kawai CA95 stands out and unleashes their issues with the humming/rattling issue. Your sound clips wasn't as audible as when you hear it in person. But, of course, thank you for making the effort to put it up. I have emailed the digital technician from Kawai and waiting for his response.

As for your second issue, I believe it's the imperfection of samples taken off the Kawai Concert Grand. But, of course, I do hope there's a fireware fix. In order to see this fix in reality, we all need to participate. I would hope everyone of us who owns a CA95/CA65 with these issues email/call Kawai and tell them the truth. I've stopped playing because of the rattling sound. If not this issue, it's a very good digital piano. I love it!

To be clear: my sound clips do not demonstrate the rattling sound from the cabinet, these are straight-to-mp3 recordings while the rattling is mechanical, audible only when listening without headphones, most likely coming from the area of power source. It is not present in my sound sound clip.

On the other hand, the "second issue" (labeled 3 in my first post above) manifests mainly when pressing damper pedal, can this be sample imperfection? I believe string resonancies (of undamped strings) are computed based on which keys are played and which are held down, right? I believe this sympathetic resonance simulation is somehow flawed that it unrealistically amplifies (and modifies) the overall sound when F3 is played, thats why I hope this is firmware-fixable. Other keys don't do this, maybe one or two others to much lesser degree.

Hello Hookxs,

Thank you for your detailed description and for posting the example audio clip.

Regarding the transformer hum, I believe all transformers hum to some extent, however there can be a degree of variance from one transformer unit to the other.
The volume of the transformer may be a little more noticeable on the CA95 due to its position within the cabinet. However, if you have any concerns about the hum, I would raise this topic with your Kawai dealer.

Regarding the F-3 key rattling, this is not an issue I am familiar with, and again, is perhaps best dealt with by your dealer.

Finally, regarding the F-3 sound issue, I have listened to the recording and acknowledge (both aurally and visually) the increase in volume. To clarify, are you playing the key, then pressing the pedal, or pressing and holding the pedal, then playing the key?

I'm afraid I do not have an explanation for this phenomenon, and Kawai Japan is still currently on holiday for the Japanese new year. However I will try to look into this when we return to work on Monday morning. In the meantime, may I also recommend that you contact your dealer and the Kawai distributor in your country (Praha Music Centre?). It may also be worthwhile to send an email to Kawai Europe's technical support address.

Kind regards,
James
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Hello James and thank you for your interest.

Yes, I play (and hold) the key and after a brief moment press the pedal, which boosts the volume. The order is irrelevant though, anytime the F3 key and sustain pedal happen to be pressed at the same time, the sound is boosted in volume and somewhat unpleasantly distorted. This boost even somehow adds up if you press the key repeatedly. While it may seem like a minor issue in the recording, when amplified by speakers (1/2 volume more than enough) it renders the piano almost unusable (I hate to say it out loud...). I must carefully watch for the presence of a particular key and pedal at the same time and compensate (or don't) - either way it damages the music and playing experience. Sometimes I get fooled by not playing F but E# instead, which doesn't raise the red flag but booom - there it is:-) I tried this on an acoustic piano and of course it does not exhibit this phenomenon. If nothing else than it is impossible from the point of energy conservation - you give the system nothing so you can't expect the volume to rise.

I plan to create and upload a MIDI file which demostrates the issue so other users can then play the MIDI and see is their piano works fine or not. I am kind of new to this MIDI world though, so at the moment I don't even now which editor to use that can handle pedals easily. I would like to have several keys played with the same velocity so that the volume boost can be compared and quantified. I also want to see if there are other keys that exhibit this behavior (to lesser degree perhaps).

I will contact my Kawai dealer (Music City Prague indeed), but should it be a software issue, I am afraid there is nothing they can do other than report higher up the chain. The other matters (rattling, transformator hum) don't really worry me since they are far less disturbing and I believe they are fixable easily. Once I have the "scientific" recording of the issue, I will contact Kawai Europe's support, like you suggested. I'll be happy if you discuss this issue with your colleagues, thank you.

Hookxs, may I ask you to create a recording with other notes in the same region, and different key/pedalling techniques.

e.g.

- Play E-3, hold key
- Play E-3, hold key, then press pedal
- Play F-3, hold key
- Play F-3, hold key, then press pedal
- Play F#3, hold key
- Play F#3, hold key, then press pedal
- Play G-3, hold key
- Play G-3, hold key, then press pedal

Also, may I ask if you have tried turning all the Virtual Technician parameters to 0 (Off)? This is of course an extreme measure, but it may help to isolate the cause of the problem.

Kind regards,
James
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Ok, I will do it as soon as I get home. The short clip I uploaded yesterday is with Virtual technician settings as I had them adjusted for normal playing, definitely nonzero. I will try to set them to Off (damper resonance etc.). But I remember fiddling with it when I first discovered the issue (at that time I wasn't aware it is present even in headphones and was looking solely for outside sources of resonance/amplification) but setting resonances to Off didn't help (far as I remember) while setting to maximum values made the problem worse (subjectively?) - I will measure this as well.

Ok so I played with the settings a bit and indeed discovered that when I set the Damper resonance to Off the problem disappears (or at least diminishes considerably). Other settings (string resonance?) may have a little effect but probably not.

I recorded the test you asked for (up to G#3), each note is played first without pedal and then with pedal some time pressed after the key is pressed. I recorded this for damper resonance set to maximum value (10), default value (5) and Off. I would like to have all the notes in the recoring with same velocity and duration (as well as pedal) but I found no quick way how to edit the midi (advice welcome). Other settings are in their default values, Reverb is off.

Recordings:
Maximum resonance
Default resonance
Resonance Off

I believe this shows that the error is not in the samples but rather in the resonance algorithm and could be therefore fixable by firmware update. It may not be such a big deal for most users, especially with headphones, but when playing through speakers I find it extremely annoying.

Hi Hookxs and everyone else here. :-) Hope you get your issue resolved. I'm currently in the process of choosing my first DP and, being a complete rookie with quite the budget, the CA-95 really impressed me with its capabilities and sound. I'll keep an eye on this thread to see how this pans out. Good luck!

(I'll stop right there so as to not hijack this thread.)

I had a technician come over my house today to have my CA95 inspected. As soon as he and I moved the piano about 1 foot away from the wall, the vibration/rattle sound was almost completely vanished. He then checked inside the piano and found a few screws "slightly" loose. After he tightened them and put everything back in place, it sounded so much better. To me, the problem is caused by having my piano too close to the wall. I was told you need to separate your piano and the wall about 1 foot or more. In the past, I thought 6 inches away from the wall was enough, but now I guess it depends. I have this helps anyone with a similar problem.

BTW, I have looked inside the CA95 and I can tell you this is a very high quality built piano. He said it's a very very nice piano. I was very happy as soon as I heard he said that.

Kenboi2: did you push the piano back to its "original position", after the screws were tightened, and listen for the problem? Did it go away after the tech was finished? Was the vibration/rattle the wall or an interaction between the wall and piano? Please expound on your comments above. I am curious about this vibration/rattle you were hearing.

HwyStar,

I tried to push the piano back to its original position and the vibration/rattle sound wasn't there anymore. I find it very strange. I forgot to mention another thing. The technician also tightened a few sets of wires other than the screws. I guess it's a common problem in the CA95 series.

I have been away some time around this topic. But this is the latest news. Kawai delivered last thursday a brand new CA 95. Because of Christmas and New year it took some time, but this is the final outcome of the Humming sound topic. As mentioned before the replacement of a new transformer could not reduce the humming sound, that's why they decided to replace the entire instrument for a new one. This CA 95 is a lot quieter but still there is on the background the soft sound of the transformer, but in no way the same annoying sound as the first one. So I can live with it.
Now something really strange happened, that I cannot explain. This new Kawai CA 95 sounds a LOT BETTER then the first one (both instruments in factory setting). The difference is really amazing. It is as if the sound of the speakers and the soundboard of this one, is so much more dynamic, livelier, fresh and sparkling. And this not only concerns the sound through the speakersystem but also via the headphone set. I'am using a pair of Sennheiser HD 595 and it's a clear fact that the piano and other samples sounds much better then those of my first CA 95. I have no explanation. Even the dealer directly noticed the sound difference between the two when I came in his store to checkout the new piano. (It was his first Kawai CA 95 he sold to me, and he remembered the sound of the first one). But I became first really aware of this when the piano was standing in my study room. Is there somebody who has a reasonable explanation of this phenomena?
Anyhow, I'am very happy. I'am also very satisfied with the service of Kawai and my Kawai dealer: Aad Veldhuis in Amsterdam. I really love this instrument and I'am happy that I choose for Kawai. Amen

Dutch Dhamma, thank you for the update. I'm glad to read of this positive outcome.

I'm afraid I offer an explanation as to why your new CA95 should sound so much better than the first piano you received. However, I expect it may have been related to the humming transformer.

Kind regards,
James
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