@andyr if I understand correctly to implement what you've suggested I would need to change speakers? (my question about bypassing the filter/crossover was a reference to what's already in the speaker, not excluding a filter/crossover altogether). 

 

 

On 15/05/2023 at 10:33 PM, almikel said:

Big call @andyr!

Of course I'm a fan of linear phase EQ applied appropriately, and well applied EQ in general (FIR and/or IIR), but I've come back to accepting well designed passively crossed speakers can sound mighty fine also!

Yes.

There was similar discussion in another thread (about bass/subs in the past 48 hours).    Assuming the speaker is fairly well designed, then you won't hear the phase error itself.... but you will hear any errors in the frequency response (which phase can be a relevant contributor to).   Which "approach is best" isn't a simple question, but it can quickly devolve into a GIGO problem, where you are correcting (the phase and/or the frequency reponse) of something you've measured, but the measurement didn't really represent reality, so the correction is "wrong".

 

On 16/05/2023 at 9:23 AM, andyr said:

I merely said that playing music through Roon's "linear-phase" Convolution makes the spkrs sound better than playing the same LP directly, outside of Roon.

He understands that.

 

What he's trying to say is that the "linear phase"-ness of the convolution, almost certainly has only a very small amount to do with the improvement.....  assuming an apples to apples view of frequency vs phase (ie. you compared identical frequency response with different phase responses).

 

On 16/05/2023 at 2:07 PM, David.M said:

an issue with all passive speakers?

Yes.  The crossovers cause a phase rotation ... but it is not very (arguably completely) inaudible.

 

On 17/05/2023 at 12:48 PM, andyr said:

IIR filters exhibit a phase-change across the XO region - this is audible

I would challenge you to audition this.    It really isn't.

 

Note:   You have to be sure though, you are auditioning just this (eg. just adding/removing an all-pass filter).   Any changes in frequency response will be audible.

 

On 17/05/2023 at 12:48 PM, andyr said:

FIR filters do not exhibit a phase change

This is incorrect (or a best quite misleading as to "what is FIR")

 

FIR filters can exhibit ANY phase change (independant from the frequency response) you desire.     eg. you can choose the phase vs frequency to be flat when the amplitude vs frequency is not flat..... or eg. you can chose the phase to change a lot, when the frequency doesn't ..... ie. it uncouples the frequency and phase from each other  (where as they are linked together in a "passive crossover").

 

So rather than "the filter has no phase change"....  it is better put as "the filter has the exact phase change I choose (irrespective of the frequency response)".

 

18 hours ago, David.M said:

Wondering though, if the filter/crossover is a problem wouldn't it need to be either bypassed or the signal processed after the crossover?

No.  You could add "phase correction" on top of your existing speaker+passive crossover....   but:

 

Doing do so can be trciky (becuase which measurement of your speakers phase will you correct for)

Theory says it should not be audible

Practise says (people who carefully audition it) that it is of quite minor audibility

Edited May 18, 20232 yr by davewantsmoore

9 hours ago, David.M said:

@andyr if I understand correctly to implement what you've suggested I would need to change speakers? (my question about bypassing the filter/crossover was a reference to what's already in the speaker, not excluding a filter/crossover altogether). 

 

No, you wouldn't have to change spkrs - simply play your vinyl through Roon, after having measured your spkrs response with REW and then set up Roon's Convolution.

 

Roon's Convolution 'corrects' the phase anomalies which are inherent in the spkrs' XOs (passive in your case ... active in mine).

 

23 hours ago, andyr said:

I was very happy using my miniDSP setup to send vinyl to my 2-way active spkrs & subs.  (Which involved an A2D converter on my phono stage, for input to the miniDSP unit, and then 3x DACs after the miniDSP, to drive the 6 amplifier channels.)

 

But I've been able to achieve a significant improvement in SQ by now playing my vinyl via Roon - using my PC's processing power and making use of Roon's "Convolution" capabilities - to turn the IIR filters produced by the miniDSP unit into "linear-phase" FIR filters!  

Hi Andy,

 

I'm a bit behind on your current setup other than you swapped your Maggies for some nice custom Open Baffles.

Is all your audio is now running through your PC to run FIR filters in Roon?

What's the setup?

 

cheers,

Mike

15 minutes ago, almikel said:

Hi Andy,

 

I'm a bit behind on your current setup other than you swapped your Maggies for some nice custom Open Baffles.

Is all your audio is now running through your PC to run FIR filters in Roon?

What's the setup?

 

cheers,

Mike

 

Hi Mike,

 

I have 2 modes of operation:

1. phono stage --> A2D converter --> miniDSP config #1 (with IIR filters and EQ) --> 3x DACs --> 6x amp channels --> 2x subs plus 2x active ZB mains.  IE, no computer and no Roon.
2. phono stage --> A2D converter --> Roon with Convolution to a. add a FIR filter overlay to the miniDSP's IIR filters and b. provide the necessary EQ --> miniDSP config #2 (with IIR filters and no EQ) --> 3x DACs --> 6x amp channels --> 2x subs plus 2x active ZB mains.

 

I can do on on-the fly comparison of #1 and #2 ... #2 sounds much better.  

 

Edited May 19, 20232 yr by andyr

@David.M - hopefully not too off topic...?

 

Thanks @andyr - so presumably your A2D converter has dual outputs, one to your PC and another to the miniDSP nanoDIGI 8x8?

And I'm assuming you run 2 inputs on the MiniDSP, one directly from your A2D converter and the other from your PC running Roon?

• What are the digital interfaces you use in/out of the PC?
• What application do you run on the PC to run the Roon FIR filters? 
• What sort of PC do you run? ie what sort of grunt is needed to run the FIR filters you've implemented?

 

cheers,

Mike

hi Mike,

 

47 minutes ago, almikel said:

Thanks @andyr - so presumably your A2D converter has dual outputs

 

Yes:

• one coax
• one optical.

 

47 minutes ago, almikel said:

one to your PC and another to the miniDSP nanoDIGI 8x8?

 

Sort of!  

 

The coax output goes into a 4-way digital source selector - the output of which goes into the nanoDIGI.

 

The optical output goes into a miniDSP USBstreamer - the output of which is USB into my PC.

 

47 minutes ago, almikel said:

And I'm assuming you run 2 inputs on the MiniDSP, one directly from your A2D converter and the other from your PC running Roon?

 

Sort of.  I in fact run 4 inputs to my nanoDIGI - these are selected with my 4-way digital source selector.

 

The output from Roon is one of the other inputs - so USB-A out of the PC into a converter-which-produces-a-coax-input for the 4-way digital source selector.

 

47 minutes ago, almikel said:

1. What are the digital interfaces you use in/out of the PC?
2. What application do you run on the PC to run the Roon FIR filters? 
3. What sort of PC do you run? ie what sort of grunt is needed to run the FIR filters you've implemented?

 

Answer #1:  Into and out of the PC is USB-A.

Answer #2:  Roon DSP.  (Con wrote this.)

Answer #3:  It's an Intel i7 ... I believe its using about 12,000 taps - when I last checked, this was about 5% CPU utilisation.

Note: Roon is not - not yet anyway! - providing FIR filters.  That's the next stage - currently it provides a "FIR filter overlay" to remove the phase anomalies which the nanoDIGI's IIR filters exhibit.

 

 

Edited May 19, 20232 yr by andyr

Thanks @andyr

 

@David.M - back on topic - I agree with @andyr and @davewantsmoore

20 hours ago, David.M said:

if I understand correctly to implement what you've suggested I would need to change speakers?

you wouldn't need to change your speakers, but you'd need to add another device in the chain to provide the appropriate changes to the frequency response and/or phase response - ie adding DSP to your system.

 

IMHO every system benefits from EQ/DSP - especially in the bottom end - but if you don't have it already, and you're happy with your "in room" sound - run with what you have and enjoy the music!

 

Mike