please tell me my fan is faulty

[DavyP]

Im sure its entirely possible that there are a few "faulty" keyboards with exceptionally loud fans.

However having returned my K61 for a K88 I feel that the fan noise is actually just "normal" and intentional as part of the construction.

I didnt feel it was worth complainig as im sure this is just standard.

I also checked a K61 on display in my dealers shop and it was producing the same level and type of fan noise.

[madbeatzyo111]

Somebody mentioned cavitation as a possibly culprit; I think this is worth investigating. Perhaps somebody could try using some baffle material around the fan (particularly the sharp edges of the HDD frame) to smooth out the turbulent air flow. Maybe lightly fill the open areas with some large pore size steel wool (this would also serve as a passive heat spreader).

[aribo61]

@GregC: if I can hear the fan with closed headphones (AKG K530) on my ears while playing a quiet piano, can't I call it loud then? It's definitely louder than is acceptable when making music. If you don't believe it, you haven't heard it. Do you think we are mad?

Back to the topic:

I opened my Kronos 61 and tried some standard ways to silence it, none of them worked. From my view, it seems impossible to make a fan of this size running on full speed more silent when it's mounted this way. Also, the fan alone is very loud (that is without any coupling to the case or metal sheet, holding it in my hand), it's simply too fast to be quiet.
I didn't find that cavitation is the main problem.

However, there *are* Kronos owners who don't even notice their fan.

So we seem to have two groups of Kronos, which means there must be a difference between those.
May be different countries get different versions?
btw, I'm from Germany...

I don't think that any minor mechanical change can make the fan silent.
The only thing I can imagine is a much lower fan speed.

I see these possibilities:

1. the fan is on a fixed speed but much lower
this would probably mean it's drived by a lower voltage, which can be simply connecting it between the 12V and 5V lines resulting in 7V.

2. the OS has a better algorithm to control the fan voltage
this would mean another software version

3. there is an additional circuit to control or lower the fan voltage

Do those with a silent Kronos hear the fan when booting?
If the answer is "yes", this would exclude variant 1.

[aribo61]

@madbeatzyo111: oh, please don't use steel wool, you may produce short circuits if some of those thin wires break and fall onto the circuit boards. You may not even notice them falling down.

[DavyP]

@GregC: if I can hear the fan with closed headphones (AKG K530) on my ears while playing a quiet piano, can't I call it loud then? It's definitely louder than is acceptable when making music. If you don't believe it, you haven't heard it. Do you think we are mad?

I have had EXACTLY the same experience and TOTALLY agree!!

The first time I switched on the Kronos 61 I was very surprised at the noise from the fan. I was playing with closed back headphones and could easily hear the fan above the Piano sounds. Maybe GregC has a Kronos with a faulty fan (i.e. the fan does is not working corrrectly??? It is OFF?) or maybe he has a hearing impediment??

[GregC]

@GregC: if I can hear the fan with closed headphones (AKG K530) on my ears while playing a quiet piano, can't I call it loud then? It's definitely louder than is acceptable when making music. If you don't believe it, you haven't heard it. Do you think we are mad?

I have had EXACTLY the same experience and TOTALLY agree!!

The first time I switched on the Kronos 61 I was very surprised at the noise from the fan. I was playing with closed back headphones and could easily hear the fan above the Piano sounds. Maybe GregC has a Kronos with a faulty fan (i.e. the fan does is not working corrrectly??? It is OFF?) or maybe he has a hearing impediment??

none of your statements about my hearing or my K88 are accurate.

[DavyP]

@GregC: if I can hear the fan with closed headphones (AKG K530) on my ears while playing a quiet piano, can't I call it loud then? It's definitely louder than is acceptable when making music. If you don't believe it, you haven't heard it. Do you think we are mad?

I have had EXACTLY the same experience and TOTALLY agree!!

The first time I switched on the Kronos 61 I was very surprised at the noise from the fan. I was playing with closed back headphones and could easily hear the fan above the Piano sounds. Maybe GregC has a Kronos with a faulty fan (i.e. the fan does is not working corrrectly??? It is OFF?) or maybe he has a hearing impediment??

none of your statements about my hearing or my K88 are accurate.

In that case you MUST be able to hear the fan noise???

[keyplayer14]

none of your statements about my hearing or my K88 are accurate.

And they wouldn't be accurate about mine either, I can obviously hear the fan when the K gets switched on but it's very quiet and certainly nothing that's audible when I'm playing with headphones. My laptop is much noisier.
This doesn't mean I'm suggesting that you don't have a problem, but judging from the poll the majority don't. There may well be issues with some boards, and if I was getting the problems that you guys are experiencing I'd be taking it up with Korg.

[madbeatzyo111]

@madbeatzyo111: oh, please don't use steel wool, you may produce short circuits if some of those thin wires break and fall onto the circuit boards. You may not even notice them falling down.

LOL, I forgot about that How about fiberglass wool? Hmm, well you might get cancer from inhaling the nano-fibers then.

There's obviously discrepancy in user experience when it comes to the perceived loudness of the fan. There's a few possibilities:

• 1) Quality control. Some Kronos are louder than most due to bad fans or bad factory install.
  2) OS/BIOS. Different versions run the fan at different speeds.
  3) Case. The larger K73/88 cases are naturally quieter than the smaller K61.
  4) User. Each of us has a different sensitivity and hearing threshold, so some may hear the same fan louder or softer than others.

I tend to think #1 is most likely since there have been actual cases documented in this forum of faulty fans. Also I think #4 contributes a little too. I'm definitely deafer now than before I took up drumming for example

[DavyP]

There's obviously discrepancy in user experience when it comes to the perceived loudness of the fan. There's a few possibilities:

• 1) Quality control. Some Kronos are louder than most due to bad fans or bad factory install.
  2) OS/BIOS. Different versions run the fan at different speeds.
  3) Case. The larger K73/88 cases are naturally quieter than the smaller K61.
  4) User. Each of us has a different sensitivity and hearing threshold, so some may hear the same fan louder or softer than others.

I tend to think #1 is most likely since there have been actual cases documented in this forum of faulty fans. Also I think #4 contributes a little too. I'm definitely deafer now than before I took up drumming for example

I tend to agree but I do not think it is 1) or 3) above as I have had both a K61 AND a K88 (and checked another K61 in store!) and they all appeared to be very much the same?? They were delivered 2 months apart and from different batches. I think there may be a few "Faulty" keyboards slipping through with maybe extreme noise but I think the likely answer is 4) as I think the noise is normal and it affects different users in different ways.

If I was playing live with a band and loud amplification I do not think I would have even noticed the noise to be honest. I did not notice it in the store when I first demoed the Kronos. Also next to a desktop computer the noise is easily covered up by that coming from the desktop.

I am sitting with my laptop and I would estimate that the fan noise is slightly louder than what is coming out of it.

However if you are using the Kronos in isolation (No stage amplification or next to a computer) the fan noise does become very noticeable to some people. Looking at the poll it would appear that we may be in a minority but it is still a significant issue.

It really annoys some people yet others do not even notice it??

For me it may be down to unfamiliarity. I have never had a keyboard that had a fan built in therefore it was a bit of a shock. I suppose other users with experience of Oasys etc.. (Any others??) would be already used to noise from an internal fan??

[aribo61]

I still hope it's about different OS versions, with the more quiet one operating the fan at slower speed (and hopefully temperature controlled).
Then the issue would probably disappear in mid october, when OS1.5 will be released.

Question:
Who has an OS version different from 1.0.4?

Another point is the BIOS. There may be different versions out there. To check this, the VGA port has to be connected...

[curvebender]

I still hope it's about different OS versions, with the more quiet one operating the fan at slower speed (and hopefully temperature controlled).
Then the issue would probably disappear in mid october, when OS1.5 will be released.

Question:
Who has an OS version different from 1.0.4?

Another point is the BIOS. There may be different versions out there. To check this, the VGA port has to be connected...

I hope you're right. Most users are saying the fan revs up at start, and then slows down when the boot process is finished.

My 61 is wonderfully quiet at startup, and then goes into jet engine mode...

[maphill]

Here's a recording: http://music.doctorobvious.net/KronosFan.mp3

Recorded with a GT AM51 condenser mic through a Yamaha 01v, mic about 18" above the screen pointed toward the Kronos.

This recording has been concatenated, but the sequence is:

On
Keys pressed (medium pressure)
Turn unit off
Turn unit on
Start up loud fan (probably the same as "high speed" when hot)
Then quiet fan (probably same as a very cold room)
Then typical fan (for my 75 degree room)
Then beep for ready
More key presses (moderate pressure)

If you listen to the recording I made, there are clearly 3 levels of fan volume for 1.0.4 (at least for my unit).

First, what sounds like full speed, and then a low speed (that I would probably be okay with) and then a medium speed before it's done loading everything.

I think I'll start a new thread that is not about "I think it is normal... no, I think it's not normal" and focus just on improving the situation.

By the way, I believe we have multiple issues at work. I do believe there are some fans that are noisier than others. And I do believe that there are some people that a genuinely concerned about the volume of a correctly working fan.

Mark

[DavyP]

My original K61 followed a sequence as described by Maphill with the sort of start/stop sequence and it did seem to be controlled by the software boot up sequence.

However the replacement K88 does not seem to follow the same sequence. I checked it a couple of days ago and it just seemed to go straight to the "normal" state??

I will check this again tonight.

I do hope that it can be controlled in software and therefore could be improved in an update.

It would be better if it defaulted to off and then only came on as and when needed if the temperature rose?? Just like a thermostat?

[aribo61]

The discussion here pushed me to open my K61 again and connect the fan to find out more.

First, I have to correct myself.
At one point I said, my fan would have only two modes:
- fast, slow, fast,
but it's really
- fast, slow, medium

My fan just sounds very similar in fast and medium modes.
I found this when measuring it's voltage.
Afterwards I could also hear the difference

The fan starts with 12V for a short time, then goes down to 5.5V and after bootup it's operated at 9V.

I then retried to decouple it's vibration from the metal sheets by using a swinging construction built from cable ties.
This worked so far, but the fan was still too loud for my taste.

So, next I applied a fixed voltage to the fan.
I tried 8V, which seemed to emit the maxium noise acceptable to me.

Then I closed the cover with some screws and waited an hour while continuously playing a karma sequence with about 100 notes in parallel at full speed resulting in 80-90% cpu stress.

The result was a little less temperature compared to the disabled fan, but not worth the hassle.
I opened the cover again and found a rather hot heat spreader on the motherboard, which may have been near to operating limits.

This made me try how the standard voltage would behave.
After an hour the outside was very near to cool, so the cooling seems to work very well at 9V.

But it's indeed too loud for me.

But I'm now convinced, that the fan may be necessary on the long term and operation at this speed level was chosen for some reason.