Hi all,

When I attach my earphone (Shure in-ear type) to the P140, I can hear a low hissing sound. Though not very loud, it is kind of annoying. Tried my friend's AKG headset and the same thing. Just wondering if my unit is defective or it is "normal" with the P140.

P.S. I am a real beginner, so there is a lot of "idle" time on the keyboard, making the hissing sound much more noticeable and distracting.

Thanks,
Richard

No noise on mine, I use several different brands of headphones. A test you could do if you have another amp, like a stereo receiver, would be to run the line out from the P140 into the stereo, then plug your headphones into the stereo headphone jack.

I had a set of headphones with an unusual impedance so I used a CMOY amplifier with them on my P140. Then I heard some low level hiss because the CMOY is kind of a cheap little device, but at least I could get full volume out of the headphones.

It is kind of strange, cos normally when you hear a hiss, the hiss will get louder as you turn up the volume. But this is not the case, I just hear a constant hiss even when volume is turned down to nil.

Mmmm, perhaps there is something wrong with my unit...

try other headphones. in-ear type might be not good for use with a DP.

Another thing to consider/check out is the possibility the hiss is coming from your ear, if it only does it when using earphones/headsets and the level of the hiss stays the same. Does it do it when wearing the headsets but not plugged into anything?

This is my problem. The removal of noise from the room by the headset causes my inner ear to hum at an audible level, or I should say it becomes "hearable" when I quiet everything down. It's probably there all the time, but I only notice when it's real quiet, for whatever reason....

Interesting thought, but I am pretty sure that the hissing is coming from the headphone. When the P140 is off, it is absolutely quiet. When I turn the unit on, there is a "click" and then the hissing starts.

I notice that different brands of headphone have different impedance. Not sure if that is a factor...

P.S. I have also tried a AKG headset (non in-ear type) and can still hear the hiss.

The "ringing" effect described by gmm is called Tinnitus.

http://en.wikipedia.org/wiki/Tinnitus

Btw, my cp33 (closer relatives) doesn't have this hissing problem. Not sure if it helps.

The Yamaha salesman said he is going to try out the P140 in his shop for me. I guess I better bring my own headphone and try it out myself over the weekend.

Funny, I have that problem with my P140 but with the speakers, not the headphones. With the speakers, there is a definite (louder than I would like) background noise that is not related to the volume. It's constant no matter if the volume is nil or full.

But with my Sony MDR-7506 headphones, the P140 is just marvelous. No hissing/background noise.

Must be your headphones. Have you tried expensive ones?

I have the same issue with my Yamaha CP33. The line outs work great though, so I plug my headphones into my sound system. I asked a friend about it who knows electronics and he said that the headphone out is amplified while the line-outs are not. I think headphone out has a different impedance too because headphones are much lower impedance than any sound system inputs would be. If they can't fix it and it still bugs you, consider buying a quality headphone amp and connecting it to the line-outs.

I'm curious about this. I would guess that in-ear headphones (earplugs?) would be very low impedence. I would also guess that the quality of the cords involved, and the connections, could vary significantly.

I would suggest that you spring for a decent set of real headphones -- say, at least on the level of Sennheiser HD-280's or better -- and see what happens. If you want to play a DP through headphones, surely you would want at least that level of cans? So the investment would seem to make sense (HD-280's can be bought for $100). Then let us know what you conclude.

Yes, I do plan to get a quality headphone like the HD-280 or HD-595. But I don't want to spend money on a good headphone unless I am sure that that hissing sound will go away. In my country, I simply can't just refund the can if it does not work out.

P.S. Actually my Shure earphone is giving me good quality sound save for the background noise. It costs as much as the HD-595.

Just came back from Yamaha, both P140 units on display have the same hissing noise. When I change to a "bigger" headphone (closed back type), the hissing noise is a lot less obvious (though it is still there).

I have a CP33 and when the USB cable is hooked up the computer, there is this hiss. Are you using the USB (or TO HOST) cable?

I've now done some further tests, which may be helpful.

As before, Yamaha P-140, with all external cables unplugged. (Plugging and unplugging usb-midi, pedal and RCA line out cables made no difference).

Test headphones:
Sennheiser HD600
Grado SR60
Sennheiser In-ear 'iPod' headphones

There was a very noticeable hiss with the in-ear phones , noticeable but bearable with the SR60s, and nothing I could discern with the HD600. The hiss was independent of volume setting.

The HD600s are the least sensitive, and the in-ear most sensitive, judging by the perceived volume.

When I get a spare moment I'll check the published impedance and sensitivity of the SR60s and HD600s.

Toby.

Quick update:
SR60: 30 Ohm, 98 dB/ 1mV
HD600: 300 Ohm, 112 dB/ 1V

Not quite sure how that bear on the case, but clearly they are quite different.

Further update:
I think my in ear headphones are CX300s, which have a quoted impedance of 16 Ohms, and a sensitivity of 112 dB, 1V.

Hi Toby,

Wow, that is a very detailed test. Yes, I suspect also that the impedance of the headphone has something to do with the amount of hiss.

Shure E3C: 27 Ohm, 115dB
Very noticeable hiss.

AKG 519: 35 Ohm
A lot less noticeable but is still there.

I am planning to get either a Sennheiser HD280 or a AKG K240, both have 50 Ohm impedance. Hope that will make the hiss go away.

BTW, does the P140 has enough power to drive a 300 Ohm headphone? I thought with such a high impedance, you will need a headphone amp.

I am also thinking of getting a pair of external monitors. Saw a small ESI nEar04. Good sound and cheap (US$150 a pair). Or a pair of computer speakers like the Creative T40. Mmmmm, seems like I am more interested in buying gears than making music. I can barely play Jingle Bell.

P.S. I have nothing connected to the P140 other than the power cable.
Thanks

I have Grado SR 60 and Yamaha P-80 and there is absolutely no hissing.

I think it is model specific. I've tried my Shure earplug with the P70 and there is no hiss as well.

eggtart,

I would say that the P140 can *just* drive the HD600 , with the volume set to max. I'm not at all experienced at the piano, so my judgement of fortissimo etc may be way off.

Normally I have the P140 line outputs plugged into a small Tapco mixer, and I use the headphone output of that. This setup allows me to mix backing tracks, percussion, LH or RH parts etc into the headphones to play along with.

Finally settled for the AKG K240S. Great sound and no hiss. My conclusion is that the hiss is due to the low impedance of the headphone. Thanks everyone for the great help.

One quick comment: I have a new cp33 that hisses. It is persistent and independent of the volume level. Of course, it is loud with in-ear headphones, bearable with HD595, and imperceptible with HD580. It also is audible through a pair of MSP5 studios I use.

The fact that the volume control does not alter the hiss in any way led me to think about the power supply. Sure enough, my local piano store gave me the wrong one. I was using the PA5D (1500mA) for the last month, but the cp33 needs the PA3C (700mA). I hope the piano isn't damaged...

Along those lines though, I think all these yamaha power supplies appear rather cheap. I bet a decent regulated power supply will make for a silent floor on these DPs! And for what they cost, there shouldn't be any floor noise!

I'm going to pick up a PA3C and see if that helps. It seems that the P-140 is spec'd for the PA5D. It could be that the PA5D is very noisy...

mahlzeit, I am curious as to why connecting a digital piano to the computer using a USB cable should affect the sound produced from the internal amplifier.

Would you elaborate please?

Kind regards,
James
x

I also have a question about sound issues and the P140. I just got mine last week with the intention of getting back into playing the piano. I wanted a real piano, but that was unrealistc given the apartment situation that I'm in. I am very happy with it in general. However, the volume seems very low - even on MAX. I hooked it up to my receiver for my sound system and again - even with my sound system turned all the way up (or as high as I can go without hissing), the sound seems low. I find the same thing happening with the headphones and also when I try and record a midi. After reading some other posts, I ordered a sound mixer thinking this might help. I don't have it yet, but I just thought I'd ask you all if this is normal for the P140? Don't get me wrong - I can HEAR sound, but it just doesn't get very loud. Thoughts?

ephef,

Shouldn't the PA5D (1500mA) be more powerful than the PA3C (700mA)?


CJ_1011,

Yes, the sound output from the P140 seems a bit on the low side. When I am using my AKG headphone, I have to turn the volume up to almost MAX. So I am thinking of getting a pair of monitor speakers to augment the built in speakers.

When hooked to your receiver you may have a mismatch between the impedence of the outs on your P140 and the impedence of the ins on your receiver.
Clyde

eggtart,

The PA5D provides more current to the DP than the PA3C. I don't know what the CP33 circuit looks like, but I would expect it to be rated for 700mA since that's what comes with the piano. Power is measured in watts, which is the product of current (amps) and potential (volts).

I bought a PA3C and my problem didn't go away. I still think that the noise is from the wall wart. For starters, these two pin power supplies are not grounded. The CP300 has an internal power supply, which suggests Yamaha addressed this issue in the higher model perhaps.