High pitched ringing artifact

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I’ve had my Prophet 12 Keyboard for a bit over a month now and absolutely love this thing, it’s a great M8 along with the Pro 3 but I’ve got a question for all of you Prophet 12 owners.

It’s strange that I just began to notice this sound that seems inherent on most all patches but I notice it once I play with it in headphones.  If I can describe it, it’s kind of a very high pitched ringing sound that becomes noticeable in headphones mostly when playing low octaves (bass sounds).  Closing the filter does not filter the sound out.  Have any of you all noticed this?  After recording a part into my daw I can get rid of the artifact with a high shelf EQ around 8-9 khz so it’s not that big of a deal, but I’m curious if this is normal behavior?

[Soundquest]

I have not seen anything like this.  Try different cords and ports out.  Watch for mosquito buzz you can get from USB into mixer. 

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It’s definitely not the chords or any circuit hum or interference.  As I noted it’s only when a key is played and the note gated on.  I’ll record it and send the audio sample to Sequential support.

[Mechamilk]

Sounds to me like a midi loop. It happened to me when i play notes in my down on the midi channel of the P12 and playing on the P12 keyboard. Do you have MIDI cables and USB connected?

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I never use USB midi on my synths, I only use midi cables into midi interface.  I don’t believe there to be a midi feedback loop.  I have had midi feedback loops before and this doesn’t behave like one.  I’m in contact with support about it but they are taking a long time to respond. 

I will try to post some audio examples here shortly so you guys can tell me if this is a sound that is inherent in the oscillators or the Prophet 12 in general. 

I have attached an audio example, it's Factory patch P1 - It's a Prophet.  Played at the 2nd lowest C without the keyboard transposed, Lowpass filter closed to 0 on the display.

If any one here can please give my example a listen and test your Prophet 12 with the same settings at that patch and tell me if yours sounds the same as mine?  I'd appreciate it.

Thanks y'all !

If you listen in headphones you will hear the faint high pitched ringy artifact I am hearing.  If any of you can confirm that

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Here is another audio example from a different factory patch. 

I believe you will hear the artifact I'm speaking of more in this example.

This is with the filter closed, so closing the filter has no effect on filtering out the frequencies of the artifact.

I can remove the artifact with a high shelf EQ at around 8-9 kHz but that takes away some bite and air :-(

[Soundquest]

Can't hear anything on my work speakers, but I don't know if I would hear 9K anyway   But you should look at spectrum on oscilloscope directly from the instrument.   Get exact frequency  you suspect between 8-9K and look for multiple that could be root of the harmonic.  Look for a pattern that might offer some clues.   I had a cooling motor on the DM12 causing me line noise.  If I run it low speed it generates less line noise.

I assume you tried swapping your headphones/ instruments?

On Audacity to fix the occasional noises that creep in, I have a program that can target (knock out) very narrow specific frequencies.  If you can't find the source you might need to go that route. 

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I just received word back from Andy at Sequential, he said he can confirm from my sound tests to him that my Prophet 12 will require a repair of the Main Circuit board.  I knew that couldn’t be normal behavior of the sound of all Prophet 12’s, if so, no one would own them!