Bi-amping and Audiolense/REQ

[mitchco]

@March Audio Audiolense is like Acourate as a custom FIR filter Designer software. The generated FIR filters needs to be hosted in a Convolver and in your case, Acourate Convolver. I use JRiver's Convolver, which also supports using a sound card as input, as well as ASIO line in and a WDM driver. If one is using computer audio for movie playback, JRiver has the added advantage of being able to delay the video based on how many taps of the linear phase filter one is using, so the audio is in perfect sync. Audiolense also produces minimum and mixed phase filters.

 

[Olli]

@Olli You could try it, but I am not sure what audible benefit will occur. I say that as Audiolense also applies an overall excess phase correction, even with the passive XO in place. There also might be some gain matching involved... It is easy enough the create correction filters for both scenarios and see what the simulation looks like and then AB listen...

Yes, you are most probably right. Even Bernt said that he does not think this would be beneficial. Just too curious to try.

Thanks!

 

[March Audio]

@March Audio Audiolense is like Acourate as a custom FIR filter Designer software. The generated FIR filters needs to be hosted in a Convolver and in your case, Acourate Convolver. I use JRiver's Convolver, which also supports using a sound card as input, as well as ASIO line in and a WDM driver. If one is using computer audio for movie playback, JRiver has the added advantage of being able to delay the video based on how many taps of the linear phase filter one is using, so the audio is in perfect sync. Audiolense also produces minimum and mixed phase filters.

Thanks @mitchco. Jriver as a video player us not really an option for me as I have other "live" inputs such as a STB and a Roku stick.

I want to try audiolense to see how it compares to Acourate generally, but also with the issue of latency for video sync. Obviously minimum phase filters are the lower latency option here but I am still struggling to get Acourate down to low enough levels. My AVR still thinks the speakers at at its limit of 25 m away!

To my mind this shouldn't be an issue with minimum phase filters. The problem seems to be more related to acourate convolver and the ASIO buffer latency. The actual convolution time is short.

Perhaps I will initially try J River as the convolver see what happens now I know it can take a sound card input.

Thanks

 

[Olli]

Looking forward to hearing what you think of Audiolense vs Acourate!

 

[Olli]

@March Audio, which Amp would you recommend for the TADs for regular wiring?
252, 502 or even 702?

 

[March Audio]

@March Audio, which Amp would you recommend for the TADs for regular wiring?
252, 502 or even 702?

Hi @Olli The 701 monoblock isn't available yet, month or 2 yet, I will be concentrating on the headphone amp first hence the delay.

Ignoring power the 122, 252 and 502 are almost identical in performance terms (noise, distortion etc), extremely similar in sound, but slightly behind the 701 in absolute performance terms. However they are still significantly better than your current nagra.

Power wise the 252 will drive the TADs (stereo pair) to about 106dB. The 502, despite being twice the power, will drive them to about 109dB. The TADs are not a difficult load, so I would question if you need the extra power from the 502. In testing I have literally end stopped the drivers on my test pair of B&W CM5 S2, so I would be careful.

Oh just checked the TAD website and it says max input of 200 watts., so my recommendation is the 252.

Hope that helps.

Alan

 

[Olli]

Hi @Olli The 701 monoblock isn't available yet, month or 2 yet, I will be concentrating on the headphone amp first hence the delay.

Ignoring power the 122, 252 and 502 are almost identical in performance terms (noise, distortion etc), extremely similar in sound, but slightly behind the 701 in absolute performance terms. However they are still significantly better than your current nagra.

Power wise the 252 will drive the TADs (stereo pair) to about 106dB. The 502, despite being twice the power, will drive them to about 109dB. The TADs are not a difficult load, so I would question if you need the extra power from the 502. In testing I have literally end stopped the drivers on my test pair of B&W CM5 S2, so I would be careful.

Oh just checked the TAD website and it says max input of 200 watts., so my recommendation is the 252.

Hope that helps.

Alan

 

[Olli]

Thanks Alan. I was considering a bit more power because I am losing approx. 25 DB due to Audiolense, I can partly offset this by adjusting the gain settings (+12 DB) in Roon‘s PEQ - but it’s still a lot.

 

[Krunok]

Thanks Alan. I was considering a bit more power because I am losing approx. 25 DB due to Audiolense, I can partly offset this by adjusting the gain settings (+12 DB) in Roon‘s PEQ - but it’s still a lot.

That would mean that Audiolense generated a filter with max gain on some frequency of 25dB and IMHO that is too much. I'm not an expert but I don't think the gain should ever exceed 12dB.

 

[Olli]

That‘s what it is - in line with @Mitchco‘s experience.

 

[Krunok]

That‘s what it is - in line with @Mitchco‘s experience.

At which frequency is that gain happening? Can you post a filter curve here?

 

[Olli]

At which frequency is that gain happening? Can you post a filter curve here?

XO 65, 12DB correction in CPD

 

[Krunok]

Nothing spectacular with that curve, I can't see a reason why the filter output is attenuated 25dB. Btw, where is 0dB level at that graph?

 

[Olli]

This is what I have with me (on holidays) - I can post it in one week or so - but why would you wanted to see the 0DB point?

 

[Krunok]

This is what I have with me (on holidays) - I can post it in one week or so - but why would you wanted to see the 0DB point?

To see at what level is maximum gain of your filter. For that same figure you have to set attenuation in the convolution engine to avoid clipping. With that approach you will have minimum loss of level and still avoid clipping.

 

[Olli]

Ok, will do once I‘m back.

 

[Soniclife]

Oh just checked the TAD website and it says max input of 200 watts., so my recommendation is the 252.

I don't know how manufacturers work out max power for speakers, I expect a lot pull a number out of the air.
There is a video of big Harbeths being driven hard with over double the rated power whilst Alan Shaw watches, he then admits, I think in a thread on his cult like forum, that the power rating was not really based on anything, and he had no idea they would take so much power.
So feel free to always recommend the biggest amps .

 

[Krunok]

I don't know how manufacturers work out max power for speakers, I expect a lot pull a number out of the air.

I don't know either, but if I was to estimate that figure I would start with measuring coil temperature after some time of continuos load.

 

[Soniclife]

I don't know either, but if I was to estimate that figure I would start with measuring coil temperature after some time of continuos load.

You would also need to check nothing on the passive crossover gets toasty.

I expect they deliberately choose conservative values to protect themselves and discourage abuse.

 

[Krunok]

You would also need to check nothing on the passive crossover gets toasty.

I expect they deliberately choose conservative values to protect themselves and discourage abuse.

Exactly.