Shelves Q Noise

I just got a Shelves for the first time and I noticed that having the Q setting turned all the way clockwise causes there to be noise that kind of sounds like digital aliasing when the frequency knob is also turned clockwise anywhere between 3 o’clock and fully clockwise. This noise actually starts to become audible with the Q setting at around 2 o’clock and keeps increasing the more you turn it to the maximum clockwise setting.

It is audible on the HP/BP/LP outputs of both parametric bands (so 6 of the outputs), and it is not audible on the main output.

I thought this was a fully analog module so this noise sounds a bit off because it reminds me of aliasing, so I’m not sure what could be causing this noise, but that’s the best way I can describe what it sounds like. Also, I didn’t see any mention of this noise in the manual, and I can’t seem to find any mention of it in this forum nor on Muff Wiggler.

Is this normal or could there be something wrong with my module?

Could you post a (.wav) recording.

Looks like a power supply issue - maybe the module picking up noise from a nearby digital module?

Is it possible that you are just hearing the actual very high Q sound of your EQ with a lot of gain? You don’t mention at which level you have the GAIN controls, but if they are turned very high clockwise, you are adding as much as 15 dB at the specified frequency, and with a very high Q that can sound like a ringing whistle, depending on the FREQ setting, which you describe as anything above 3:00.

If you send a short pulse to the EQ input with these high Q settings you are doing what we call “pinging the filter”, and you can get some great sounds this way.

Please forgive me if you already know all this - it just sounded to me like you might simply be hearing the high Q of your Shelves.

A .wav recording as @pichenettes suggests should clear this up.

I just had it in a 4ms pod with one other small analog module. I also just tried it in a different case with different power and I get the same results. Here is a link to what I’m hearing:

Thanks for the tip, but it’s not just the normal high Q sound. Also, the Gain controls don’t affect the HP/BP/LP outputs, only the main output. I just posted a link to the noise I’m hearing.

Shelves, like most state variable filters, will self-resonate easier at higher frequencies. So as you sweep your cutoff upwards, the filter eventually starts self-resonating at a frequency where you don’t hear it so easily. This high frequency signal is then clipped by a later amplifier/audio interface, which results in the noise you hear.
Probably normal.

If this were the case, why would it not be audible on the main out? I’m using an Expert Sleepers ES-9 interface … is what you are describing applicable to all interfaces or which are some ones that would not clip Shelves at these settings?

I think probably only some analog to digital converters are capable of producing this noise. I said “clipping” in my last post, but that’s not quite what’s happening, regular analog clipping will not produce this weird aliasing-like noise.
Try lowering the level of the Shelves output dramatically before going into the ES-9, this should reveal if this is the problem.
I had this problem myself, and I could make it vanish by just making sure I didn’t hit my converters with too much signal.

Do you get this noise without going through your interface?

A customer complained recently of an issue with Veils when connected to the ES-8; and I found out that the ES-8 uses TL07x (or TL06x) as buffers, an odd choice because of the phase reversal that occurs with these op-amps when the signal reaches -10.4V. In terms of sonic quality, it is much more harsher than mere clipping.