37's External Input : Noisy?

[ChiLam]

Hello,

I'm just wondering if my external input terminal and knob are behaving correctly?

The output terminal on my 37 is completely silent but I noticed that the input is not. Just placing my fingers gently on the insert cable introduces noise to the signal. Any slight movement of the cable results in further noise. If I do the same to the output jack there is no noise at all.

In addition I notice that the EXT IN / FDBK knob in the mixer section is also a bit noisy when adjusting. This I would have expected was normal when no jack is inserted and it is being used as a feedback circuit but it remains noisy when a jack is connected for external input. Any movement of the knob will generate a kind of electrical scratchy sound and is quite noticable above the source signal.

I have tested the Audio input on my "noise-prone" Minibrute using the same source. The Minibrute stays silent in all similar situations - touching/movement of the input cable and adjustment of the EXT IN level fader.

Is this part of the design or a faulty input terminal possibly?

Any help much appreciated

EDIT: I just checked using Headphones and the noise when the turning FDBK knob only happens when a key is pressed - even if the all OSC's are turned off. The noisy input terminal is now silent too - even when moving the cable! It seems to only happen then when a) a signal is being sent through the input b) when the envelope is being triggered by a key press or c) Latch mode on the AMP ENV is engaged.

[Bald Eagle]

I don't notice any type of noise that you described on mine.

[ChiLam]

I don't notice any type of noise that you described on mine.

Thanks for checking! So no noise at all even when-:

1. Engage the AMP ENV LATCH mode on
2. FDBK circuit in the mixer turned on (no jack inserted into EXT IN)
3. Turn off all OSC's
4. Then turn the FDBK knob?

[Bald Eagle]

I don't notice any type of noise that you described on mine.

Thanks for checking! So no noise at all even when-:

1. Engage the AMP ENV LATCH mode on
2. FDBK circuit in the mixer turned on (no jack inserted into EXT IN)
3. Turn off all OSC's
4. Then turn the FDBK knob?

If I follow those steps I do get a slight scratchy/hissing sound when turning the FDBK knob. The noise stops when I stop turning the knob. I don't really notice it until I have the volume turned up at least half way. I'm going to assume this is normal, just the nature of the circuit picking up voltage changes.

The noise changes depending on filter settings. With FDBK turned up enough you can get some interesting effects playing around with the filter and feedback without having any OSC turned on and without playing any keys although not sure how useful this would be.

[ChiLam]

Thanks again!

After more testing I notice that the noises only happen when either of the AMP Sustain or the Release are set to high values!
This is true for both cases - using either the internal FDBK or the EXT IN with a jack plugged in.
All inteference completely dissapears once I turn these parameters both down - even the noise from the input jack goes away!

I guess this is why it became so noticable last night when I was running drums into the input - I had both the AMP sustain and release fully up to the longest setting with latch on.

Im pretty sure now that your right and this is completely normal.

Phew - for a moment there I began contemplating having to send her away - god forbid!

Cheers for the help!