DSP4000 48KHz sampling rate noise

[vasquez]

I own a DSP4000 rack unit and I’m having a bit of a problem. When I’m running at 48KHz sample rate in standalone mode I hear a high pitch oscillation going thru the analog audio outputs. Same thing when running at 32KHz. This oscillation is highly audible when running chorus/flanger effects. When switching to 44100Hz it’s still there but in lower volume. I checked the cables, even ran with headphones straight to the output jacks. Any idea what that could be and if it’s fixable? Thanks

[nickrose]

Obviously this could be any kind of hardware-related problem, but my guess is you have some kind of ground loop.

In the DSP4000, there is a lot going on at 1/4 of the sample rate (12k @ 48kHz), and this can appear if you have a ground loop.

Disconnect all cables except for one output, and see if it changes.

 

[vasquez]

I’ve removed all the cables from the unit (XLR inputs, XLR outputs, SPDIF in used for syncing to external clock) and used another power switch that is not connected to my Furman switch. It shows the same behaviour. I’ve connected two jacks on the outputs and recorded with a Sony PCM D50 recorder with max input gain. The noisefloor is around -78db. I’ve attached a screenshot from Audition and also uploaded the recordings that have been normalised to -0.1db.

I’ve used two presets:

Digest Inn (Chorus/Flangers) with 32000, 44056, 44100, 48000 samplerates

External Detune (Chorus/Flangers) with 32000, 44056, 44100, 48000 samplerates

https://www.dropbox.com/sh/yvm6uzhgchlid8x/AAAmHyC1ssvfZSha3uU9skP0a?dl=0

Please have a listen of the 48000 recordings, they all have a dinstinct oscilattion in the signal.

[nickrose]

This is now a twenty year old machine and may have any number of things wrong with it.

We no longer support products as old as this, but if you want to get it serviced, look at https://www.eventideaudio.com/support/repairs

 

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