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Unstable volume on the Tetra

Unstable volume on the Tetra
« on: September 05, 2017, 07:44:07 AM »
Hey everybody!
I own a TETR4, and for some reasons, whenever I push the Program/Combo button, the output volume jumps up in about 10db. Then if I move the volume knob (the slightest change) it jumps back to the original volume.
Anybody experienced that problem and knows how to fix it?
I updated to latest OS and voice
Thanks!
Micha

Re: Unstable volume on the Tetra
« Reply #1 on: September 05, 2017, 05:12:34 PM »
It's because the parameter value of the master volume potentiometer needs to be scanned after changing between modes, and as soon as you nudge the pot even a tiny bit the value is updated. This is just how the Tetra works.
Dave Smith Instruments

Re: Unstable volume on the Tetra
« Reply #2 on: September 05, 2017, 05:45:16 PM »
Ok I see. So just to be sure, does that mean that after editing a parameter, in order to exit the edit mode I have to press the Mode button that would cause a volume change? Is there maybe a different way to exit edit mode without hitting the mode button?

I've also noticed that if I leave the instrument on and don't touch it for a little bit, the volume drops down and I have to tweak the volume knob again. Is that normal?

Thanks a lot!

Re: Unstable volume on the Tetra
« Reply #3 on: September 05, 2017, 06:45:03 PM »
The volume knob is not a stored parameter value, which is why it works that way. Everything else is saved as part of the program so volume is the only parameter that works like this.

If the volume is dropping after not touching it for a while it's likely because the pot is on the edge of a value or dirty, and is sending a volume message to the Tetra. Try turning the volume knob through its full range around 10 - 15 times and see if the issue goes away. Also, if you have MIDI or USB connected the Tetra could be receiving a volume message over MIDI.
Dave Smith Instruments

Re: Unstable volume on the Tetra
« Reply #4 on: September 06, 2017, 06:52:41 AM »
Ok , thanks a lot for the help!
During the process I've noticed a 2nd issue-
If I turn the volume all the way up, there's a soft but noticeable high pitch noise coming out of the tetra.
I've checked it on my mopho x4 using the same gear, same instrument cable and power supply and its clean, so the noise is from the tetra output only. Any idea about this? Also tried a different power supply, different socket and different instrument cable, the problem persisted. (I had no usb/midi connected to it)

Thanks again!
Micha

Re: Unstable volume on the Tetra
« Reply #5 on: September 06, 2017, 11:29:21 AM »
Hard to say without hearing it, but it could simply be oscillator bleed. The Curtis chips used in the Tetra have about an 80 dB signal to noise ratio, so it's possible to hear some low level oscillator bleed even when the VCA is fully closed. Due to the tolerances in the analog chips there can be some variation in the amount of bleed from none to "some", which could explain why the x4 didn't exhibit the issue in the same way.

If you'd like to go deeper into this inquiry, please contact our dedicated support channel. I suggest capturing a recording of the noise in that case: support (at) davesmithinstruments.com
Dave Smith Instruments

Re: Unstable volume on the Tetra
« Reply #6 on: September 13, 2017, 01:19:46 AM »
Ok , thanks a lot for the help!
During the process I've noticed a 2nd issue-
If I turn the volume all the way up, there's a soft but noticeable high pitch noise coming out of the tetra.
I've checked it on my mopho x4 using the same gear, same instrument cable and power supply and its clean, so the noise is from the tetra output only. Any idea about this? Also tried a different power supply, different socket and different instrument cable, the problem persisted. (I had no usb/midi connected to it)

Thanks again!
Micha

My Tetra is the same, a constant high pitched whine out of it.  I just don't turn it up full or turn the channel down when not in use if I do want full gain out of it.  Just gotta live with it I guess :/