Flanger thumps

[BassinCT]

I'm new to effects and have picked up a used MXR 117R Flanger. I like what it can do, but I hear low-level audible thumps (sounds like a heartbeat through a stethoscope) that correspond to the speed of the sweep while there is no signal.

Is this normal with this type of effect?
Any help is appreciated!

 

[Skrogh]

It happens... I don't know about the MXR 117R, but usually in analog effects with an LFO, the LFO will bleed through (ticking). Make sure you are running it on a clean 18v psu.

 

[Berme]

My Maxon flanger does it too. Nearly inaudible.

 

[bassteban]

The one flanger I've used is the old DOD FX-75(B, IIRC; it's on loan to a guitarist bud). It was very noisy when on, can't recall but it seemed to *wheeooeeoosh* a little when off. I diddled w/the internal trimpots, trying to get the perfect *Barracuda* tone- might've made the noise worse, although it nailed the song pretty well to my bad old ears.
I'd also like to hear if this is an inherent flanger thing.

 

[BassinCT]

Thanks for the replies- I had not yet tried the unit with the power supply until a minute ago. I noticed the thumping when using batteries, but with the 18v power supply, the thumping vanished.

 

[Laurent]

The MXR is a very good unit in general. One of the best. I don't remember mine ever doing this. Sounds like a weak battery. That click sound is pretty common with some analog flangers. It's actually a short oscillation coming from the feedback loop; the circuit that provides the resonance. My DOD flanger does this on high settings but it's discrete.