Focus Fidelity Filter Designer

[Confused]

The update from @Focus Fidelity was quite timely for myself. I had settled on a convolution that I was very happy with, although last weekend I did find myself wondering "is this just a fraction too dark? Anyway, I tried the "beta" version this morning to make some fractionally tweaked convolutions, and I am happy to report that everything seems to be working as it should. So more like an alpha release I would say.

@Vivialet was joking about Focus Fidelity taking over Devialet software development in an earlier post, but I think he might have a point.

[markush]

It would be so great to have a thorough solution just not via Roon - rather than everything connected to the Devialet. That’s what Sweet Room was trying but so far quite failed. Maybe being able to integrate the Focus Fidelity solution on a core/base layer would be really exciting.

[Vivialet]

if Devialet would add a convolution engine it would be easy. Convolution is not a secret and there are lots of existing solutions that use this approach.

[Focus Fidelity]

if Devialet would add a convolution engine it would be easy. Convolution is not a secret and there are lots of existing solutions that use this approach.

That would be the best and most flexible approach.

[Confused]

Does anyone know exactly what is required to run FIR filtering? (Convolution Engine)

I know that the CI board has a 1Ghz Quadcore ARM processor, 1Gb DD3 RAM, 4GB flash memory, and an Analog Devices SHARC chip for DSP. This is on top of whatever is included in the "EVO Platform". (which runs SAM etc.)

This is a little beyond my limit of knowledge. Is anything else over and beyond the above required to support a convolution engine?

It would be great if this could be done and would give Devialet a unique advantage over very many systems. There are not many alternatives that can offer proper room correction convolutions that can be used to play vinyl for example.

[Vivialet]

I have a NUC10 i7 which is a pretty fast CPU, but it is only using 2-4 % of one core during playback with convolution.
Running convolution on the CI board would not have any effect on the other inputs, I guess Sweet Room is running on one of the Sharc processors.
If this processor is good for a parametric EQ or SAM it should be good for convolution I guess.

[Focus Fidelity]

The FIR filters generated by Focus Fidelity are typically 32768 or 65536 taps long for sample rates of 44100 and 48000, the number of taps required is proportional to the sample rate (to maintain the same filter length is seconds) so at 192000 the filter would be 131072 or 262144 taps long. Someone from Devialet would need to comment on what the Devialet hardware is capable of.

[ogs]

The current signal path within Expert amps does not support taps required to run adequate FIR filters. I talked to @Mathieu  about this back in 2019. There is room for EQ, i.e. Sweet Room, but not convolution. Even 32768 taps is probably "far too much" in this context, but 32768 is already too little to run proper convolution at 192kHz (which is the working rate for ADH)

The CI board might  support convolution, but AFAIK this would require a rather radical re-design of the internal signal path architecture. I am definitely not sure about this though.

[Vivialet]

Convolution in the CI board would not be worth the effort. The CI board always needs an external data source where convolution is already widely supported. Roon, jRiver, foobar, they all support convolution.

[ogs]

Well, RAAT is running on the CI which means ethernet and wifi runs there too. Maybe USB and AIR, but other inputs like AES/EBU, optical and coax SPDIF still uses the "old" signal path - I think.
Convolution in the amplifier would be excellent as all inputs (incl phono) would then go through the same convolution filter.