sharp and piercing high pitch /frequency coming out from Harbeth C7

You need to try a different amplifier to try and locate the cause of the problem/verify that it's really a fault in the speaker.  The standard process of elimination.

what frequency

I agree that you should try a different amplifier with the speakers, and also perhaps a different CD player, though I think the odds are better with the amp.

I had a CJ preamp some years ago that ended up with a bad capacitor in the power supply that generated noise beyond my range of hearing. It was only when my son visited from college and pointed out the issue that I became aware and was able to fix it. 

There is also the possibility that your amp is running out of power when you hear the distortion, but you really didn't say how loud you listen, or in how big of a room.

Lots of possibilities, but you just have to work through all of the components one at a time to find the cause.

I just had similar and, after trying a different amp, the high pitch ringing went away. I just sent the amp back to the manufacturer to check for problems. 

I experienced similar issues when I made the change from 40.1's to 40.2 Anni's.  Changing the amplifier may help some, but the fix for me was experimenting with placement, most notably toe'ing in the speakers so the tweeters align to cross in front of my listening position, as this minimizes room reflections.  I'm also increasing my room treatments with emphasis on addressing first reflection points and increasing diffusion.

its the amp or the room

not likely the speakers - its garbage in garbage out with speakers

Thank you all for your advice. However, I tried a more powerful Amp with 300 W per channel, the frequency is stronger. I also brought the speakers to another audio shop for testing. The same tracks with the sharp freqency happened on the Sonus Faber speakers too. But the sharp frequency was lessen by the high end speaker cable with filtering so I upgraded my cables too.

I avoid turning on the volume too loud, like just turing it not over "12:00 o’clock". I agree that It might be the power supply and the electricity fuse..... and also the placement of the speakers. I have moved them and they sound better now.

Speakers > amps > CD
Are you sure it's not the CD source?

whats the track?

if you switched amps and speakers and the sound is still there - then it may be your source, or even cables, if its some kind of emi (airborne noise pollution captured by rca cabling)

One other thought -- there are bad recordings. Sometimes the original master is done using microphones that have their own frequency response anomalies, or the engineer messes with the frequency response -- perhaps because the studio monitors had a dip where your speakers do not -- or due to a number of other reasons.

The problem is that once the recording is released, you as listener cannot do anything to change what is on the CD. The problem with buying a pair of speakers that fix a specific bad recording is that they will then apply the same "fix" to all of your good recordings. And, that "fix" may not work for other bad recordings that have different problems.

I know it can be very frustrating to have a favorite performance that has been poorly recorded, but life isn’t fair. The one possible solution is to buy a frequency equalizer for those situations and see if that helps improve things.

This is definitely not a speaker malfunction.  Your problem is up your equipment chain.

Sometimes the original master is done using microphones that have their own frequency response anomalies, or the engineer messes with the frequency response -- perhaps because the studio monitors had a dip where your speakers do not -- or due to a number of other reasons.

Which is why you need an equalizer in your system. It should be illegal to sell speakers without EQ. 

Both channels?  Equally?  Tried swopping L and R connections?

@noramnce @jjss49 i am looking into the RCA cable and the power supply now because this problem happens on CD not vinyl.

@mlsstlyes, agree and i thought about it. However, i have already chosen those with DDD recordings, DECCA, EMI, etc. And it is funny that seems like every time i hear the same track , i taste different things.

i talked to a cable company guy, he said my cable is too bright and sharp for harbeth. He suggests another brand which can “ pull back” the top notes a bit with warm and sweet sound.
maybe the resonance causes a peak with certain treble frequencies.... seems like this way, kind of....

@kenjit the tracks are :
Aida Garifullina, Cornelius Meister, ORF Radio-Symphonieorchester Wien ‎–Aida Garifullina

track 4

What's the recording and music? In my experience all Harbeth don't show a sharp piecing treble, even if you use the brightest amp, electronics or cables. Hence I am suspecting the music or recording to be the culprit to the bright sound you are getting with the C7ES3 40th Anniversary. Perhaps the 40th anniversary was tuned to have a treble peak, that I'm not sure but the original C7ES3 actually sounds a bit warm to my ears when compared to SHL5+.

I have had problems with sounds generated by other DACs running when I am using my newest & best one. Be sure that the only equipment powered up is the gear you are listening to. The fact that playing LPs is fine is proof that's it's not your speakers. Pull your RCA phono plug cables in and out of their sockets a few times to get clean connections. If your cables have arrows on them, are they pointing in the right direction (generally, toward the preamp or integrated amp). When playing music when you hear the bothersome noise, one at a time, pull the cables coming into your preamp/integrated amp from unused sources out. That one that stops the noise is the one to investigate. I am using class D amps that run at very high frequencies. That ultra high stuff can leak out of the cabinets and interfere with DACs. If all of the previous checks fail to resolve the problem, pick up each connected source component and rotate it 90 degrees in any (and every) direction to se if it changes the unwanted noise. If it does, be sure you are using shielded interconnecting cables. If you can see three wires wrapping around each other, it's not shielded (like Kimber PJB). Good Luck. Feel free to contact me if none of these things work. Good Luck!

I have the same feeling from my Harbeth C7 in comparison to my Gershman Avant Garde and Tyler Linbrook Signature systems.
The high pitch violin or horn sounds a bit harsh with high volume.  However, at mid volume, I am just OK with Harbeth.

Different cables might help make the sound a bit smoother, or tube amps might help. But then, you might not like other (more dynamic) kinds of music. I guess that is why many audiophiles keep multiple setups for different kinds of music or preferences.

@ryder
it is glad that you did not have this problem on the Harbeth. I tried my cables and another better speaker cables on the Sonus Faber speakers in another shop and the sharp frequency happened too. 

i am checking directly with harbeth to see the spec. difference between 40th anniversary and the regular C7. thanks : )