APC40 creating high pitched noise

[Tone Deft]

dunno. the power supply is the first suspect as it's a switching power supply which by nature are noisy but they're designed to put that noise above the audible frequencies, BUT a cheap supply can be right on the hair edge 'cause it's easier to design them that way.

other than that... maybe it's the way the uC toggles the LEDs, it's at a rate that causes them to vibrate.* I forget the name of that phenomenon.


*LEDs can be made to vibrate, most anything can, but by nature with just a DC current passing through them LEDs don't hum.

[8O]

But the PSU is external isn't it? Just DC in the APC-40 itself. Unless it's the wallwart noise that people are hearing.

Something dodgy with the uC clock maybe? Would be surprising though...

[Tone Deft]

noise can couple into the box conductively from the power supply. there's a million ways to make those wrong, only a few ways to get them right. that makes more sense that the uC polling theory, power supplies would vary, the scan rate for the software would be the same for every APC.

has anyone tried a different power supply? that would be the definitive test, isolate the variable, test it.

[8O]

Or can you run the APC-40 off a bench power supply just to try it out? I would if I could, but I don't own an APC-40 yet. Or a bench power supply for that matter...

[Tone Deft]

true. I've got bench supplies and a bunch of random wall warts.

I might try that later this week (busy tonight.)

[Spazi]

I can understand why people are a bit frustrated with the fact that it makes a slight "hum"...
You have payed for something that you want to work flawlessly.
But seriously, controllers with motorized faders make more noise than the APC40 hahaha!
I tried putting mine in "vegas mode" and then the hum pitched up and down, so it's something internal alright.
But I also think that some might hum more than others, because there are so many countries and different voltages.
In my country for instance, we have 220 volts and 50 hertz. In USA there is 110 volts and 60 hertz, so could it be the voltage differences?

Anyway, Is there a picture on the net with a dismantled APC40? I don't dare to take mine apart!

I might even take it to my radio mechanic, he should figure out whats wrong.

[toph]

I might even take it to my radio mechanic, he should figure out whats wrong.

If you do so, please keep us informed!

C.

[MacGuffin]

what's the bottom line on this? do all units do it?
Mine does it and it's kind of annoying. I don't really 'hear' it when music is playing, but I still feel the annoying pressure in my ears.
And I feel relieved when I turn it off

[jbone1313]

Wow, I found this thread after noticing this noise and searching for it. Its sucks. I noticed the lack of noise after I turned it off, and I was like, "wow something sounds better."

After that, I figured out the sound was coming from the APC40.

So, what's the deal? Do all APC40s do this? Should I exchange it for a new one?

[jbone1313]

Bump.

Anyone know if all APC40s do this?

[exper]

My first one did it, I took it back to GC about a week later, told them about the noise, which they were already aware of. I asked for a replacement with a higher serial number, and now the new one I have is silent so far. I've had it for about 2 months now, and it is fine it seems. So, maybe it was an issue with the first batches of APCs.

[jbone1313]

Update:

So, I exchanged my unit for a new one. The noise remains.

I called Akai and talked to their support. They said they are aware of the issue. They said engineering looked at it, and they determined there is no technical defect; and, that's just how it is.

The guy on the phone said he thinks its an internal power supply making the noise.

He said there has been no change in the production of the units.

Some more observations:

1. Maybe the components in the newer models do not have the problem--even though they are the same components.
2. From what I can tell, most of the non-serial number info on the UPC of my new unit is similar to my old one. It says "JAN" on there. I wonder if that means it was made in January.
3. Tone Deft indicated his was not buzzing, and his "number" (I don't think that's the actual serial) is: 825215 00238. Mine is 825213 00238. It was the same on both my old and new unit.
4. I've tried many different power supplies; none helped.
5. I've tried different outlets, and this trick I used to stop an electrical noise on my laptop. None helped.

Some more questions:

To those of you with non-buzzing units, would you mind verifying:

a. Whether or not your UPC number is the same as mine?
b. Whether or not your's says "JAN" on the label?

If the answer is "no" to both of those questions, I would say its evidence this problem has to do with a certain batch.

If so, I will go back to the shop to see about swapping for one with the different numbers. I might even wait until near the end of my return policy date, so I have a better chance of getting a different batch. However, the guy at the shop said the new one I got was a new shipment.

If the answer is "yes", then I probably won't bother.

Ultimately its a machine, and machines make noise. I will live with it if I have to, because the APC is a great piece. But, I still feel like trying to resolve it a little bit more.

-Thanks

[toph]

Hi jbone,

I know you're not asking for this, but mine is also UPC 825213 00238 and it has the buzz-issue too. But I can't find "JAN" labeled anywhere. If you mean the Charakters on the same label, in my case it's "ADA1".

I contacted German support a while ago and they also told me, that it's not defective, but as I work at very slow volumes at the studio the hiss/buzz is still driving me crazy and I tend to turn the APC off at longer studio-sessions.

Best
Christoph

[jbone1313]

Here's a little more info. I talked to support again, and I asked them how to find out when the units were made based on the serial numbers.

Apparently it works like this:

Consider this serial number: (21)K20909xxxxxxx

The four numbers after (21)K2 are the year/month the units were made. So in the case above, that unit was made in 09/09.

My unit was apparently made in 09/09.

If that's the case, I suppose its unlikely a newer unit would necessarily solve the problem. A different unit would perhaps--if the issue is inconsistent.

But again, it doesn't seem like a later batch necessarily solves the problem.

I guess I'll just try to cope.

I'll just keep telling myself that its a "powerful machine". Powerful machines make noise.

Hopefully I can damage my hearing enough so that I won't even be able to hear it!

[Akshara]

I've not run detailed tests on this, so cannot say for sure, yet it seems that when the APC40 is plugged into my powered USB hub that the noise is less noticeable. The power supply for the USB hub itself makes a very similar noise, unless something that requires USB bus power is plugged in then it stops.

Edit: Just ran several tests with and without the USB hub, and with different device configurations on the hub, while not running Live or the nativekontrol plugins, and did not notice a change in the environmental sound of the unit, so this is not the reason for the apparent volume change.

However... I'd also noticed that the noise appeared to come and go depending on what I'm doing with the APC40. When I first started using it, the noise was there all the time and drove me nuts; then I got nativekontrol's CP1 plugin and began running it in Navigation mode most of the time, and then I never noticed the noise, like it just went away.

Edit: Just confirmed through testing that when running the MT Player with the NativeKontrol CL2+TC2 plugins, the environmental noise disappears.