Allo Revolution DAC OSF filter bypass

Audio Gear Talk Allo
1

I have a question in understanding the usage of my new Revolution DAC. You can bypass the internal FIR filters (oversampling filters) of the DAC chip by a setting.

But what does this mean? I’m streaming from Roon to HQPlayer (with upsampling to DSD256) to Allo USBridge Signature and to Allo Revolution DAC.

I’m using HQPlayer filters so I don’t want to use the 8 internal filters of the Revolution DAC to prevent double filtering.

Are these filters bypassed if I set os filter bypass to on?

2

What, you can’t hear a difference? :wink:

The easiest way to tell is the impact this setting has on volume control. With ISF enabled (bypassed) you will lose hardware volume control.

3

Yes, I can’t hear the difference - because the Revolution DAC will reach me this Monday. :grin:

1 Like
4

As I understand DSD files or streams cannot be changed by filters oslt. They have to be reconverted to PCM first. Because I don’t want this, I hope for one of the 2 things:

  • the DAC is bypassing all DSD input unchanged to the DAC chips
  • if setting OverSamplingFilterBypass to on the input signal isn’t converted back to PCM and bypasses the filters unchanged

I asked Allo, let’s wait their answer.

The Revolution DAC itself… I can only say “WOW”! Souch an analytic sounding, perfect 3D shape formed, big stage. A real improvement of my digital chain.

I’m in the phase of hearing with the DAC to get all the details, so still learning.

One big disappointment (not Allo’s fault): some productions obviously use a weaker microphone for the singer. Voices sound a bit dull. The Revolution DAC shows this IMHO bad technical recording or mastering - merciless!

5

Allo answered my questions in another forum:

“I heard that changing DSD-files or stream is technically impossible if it is not previously converted to PCM again” - Filters applicable only for PCM, not applicable for DSD native playing.

OSF bypass mode also for PCM.

H2/H3 is- THD Compensation .THD Compensation can be used to minimize distortion from external PCB components and layout through the generation of inverse second and third harmonic components matching the target system distortion profile. so H2/H3 values set default values.

“Last not least: the sync/async setting is not influenced or disabled by DSD input or OSF-B?” - ODF-B not applicable for DSD , sync and async applicable for DSD