Bi-amping and Audiolense/REQ

[March Audio]

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.

Aaahhh dont confuse power output with gain. You just need to raise the input volume/voltage. 25dB BTW is excessive, you really shouldnt, and shouldnt need to, be EQing that much.

I have never needed to go beyond 10dB with Acourate. We can work through this when you get back from Hols. Enjoy yourself.

 

[March Audio]

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 .

Whilst its true that most drivers will take quite a lot of abuse in terms of clean transient power they still have limits in terms of excursion and long term power rating. They get hot! The 502 amp can make my B&W CM5 S2 literally hit the end stops with a crack. The P250 power output is still 25% above the rating for those TADs so you have to question the benefit of going further.

 

[Olli]

Ok, will do once I‘m back.

Here it is:

 

[Krunok]

Here it is:
View attachment 22656

What are the red lines on the graph? Simulation or actual response?

 

[Olli]

What are the red lines on the graph? Simulation or actual response?

Simulated response. But according to @mitchco it is almost identical to REW measurements: "This [REW measurements] matches very well with the AL5 simulated frequency response, including the same -3 dB points. "

https://audiophilestyle.com/ca/ca-a...nd-room-correction-software-walkthrough-r682/

 

[Krunok]

Simulated response. But according to @mitchco it is almost identical to REW measurements: "This [REW measurements] matches very well with the AL5 simulated frequency response, including the same -3 dB points. "

https://audiophilestyle.com/ca/ca-a...nd-room-correction-software-walkthrough-r682/

Yes, it should, but obviously there is only one way to be sure and that is to measure and compare them.

I suggest you also measure response when both speakers are playing as that one is relevant for LF response (up to app 300Hz).

 

[March Audio]

Simulated response. But according to @mitchco it is almost identical to REW measurements: "This [REW measurements] matches very well with the AL5 simulated frequency response, including the same -3 dB points. "

https://audiophilestyle.com/ca/ca-a...nd-room-correction-software-walkthrough-r682/

Hi Olli

Is that the intended in room response?

A flat in room response will sound thin and bright. Anechoic on axis speaker response does need to be flat but this becomes sloping when measured in room. There are a number of similar sloping target curves that have come out of the various research that has been done over the years. I have come to the conclusion that the 10dB straight slope from 20Hz to 24kHz (or 20kHz) is best. Your taste might vary from that.

 

[Olli]

Impossible for this one. I've moved the subs into a new setup in my guestroom. But I am moving in 3 weeks, not sure if I have time to measure again before.

But here's a measurement of this, including the filtered measurements and the simulated result (new setup is with the very nice March 252):

 

[Olli]

Hi Olli

Is that the intended in room response?

A flat in room response will sound thin and bright. Anechoic speaker response does need to be flat but this becomes sloping when measured in room. There are a number of similar sloping target curves that have come out of the various research that has been done over the years. I have come to the conclusion that the 10dB straight slope from 20Hz to 24kHz (or 20kHz) is best. Your taste might vary from that.

I know, my current target is somewhat not popular amongst many. I am still experiementing with the target design, I've tried mostly two others:

and

 

[March Audio]

I know, my current target is somewhat not popular amongst many. I am still experiementing with the target design, I've tried mostly to others:

View attachment 22661

and

View attachment 22663

Top one, the second one is still very close to flat

I had flat to 1kHz with a 6dB slope to 20kHz for a long time, but changed to the 10dB overall slope.

Have you got Floyd Tooles book?

 

[Olli]

Top one, the second one is still very close to flat

I had flat to 1kHz with a 6dB slope to 20kHz for a long time, but changed to the 10dB overall slope.

Have you got Floyd Tooles book?

No, not yet. But it's on my list!

 

[March Audio]

No, not yet. But it's on my list!

There is a recent revision, so check which one you buy. Its really essential reading IMO.

Have you seen this lecture?

 

[Krunok]

Impossible for this one. I've moved the subs into a new setup in my guestroom. But I am moving in 3 weeks, not sure if I have time to measure again before.

View attachment 22660

But here's a measurement of this, including the filtered measurements and the simulated result (new setup is with the very nice March 252):

View attachment 22659

I really like that picture with 4 of your friends moving you!

 

[Olli]

 

[mitchco]

@Olli Yes, I can confirm in Acourate and Audiolense that the simulations match the measured in REW perfectly - done it over a dozen times in both programs and don't even bother any more.

Agree with the downward slope or tilt of 20 Hz to -10 db @ 20 kHz provides the most neutral response in my experiments. And seems to agree with the R&D that Floyd Toole and Sean Olive have performed, which I wrote a summary, peer reviewed by Sean Olive: The Science of Preferred Frequency Response for Headphones and Loudspeakers.

Here is the measured response of my system at the LP using default REW settings with a 500ms right window:

Aside from constant directivity horn equalization, this was taken before I used partial correction to 8 kHz. For some waveguides and compression driver combos, I find leaving the top octave alone sounds less strident, as does using a very small value (e.g. 1) for HF excess phase correction. Then the HF eq is acting more like a tone control.

Hope you have fun in your new space!

 

[Olli]

Amazing response. What settings are you using in the CPD window?

 

[RayDunzl]

Wow on the 25dB adjustment above...

I think I use -6dB through the DSP as the safety margin.

I end up with some big cuts in the bass, but no boosts to speak of.

 

[RayDunzl]

Here is the measured response of my system at the LP using default REW settings with a 500ms right window

I'm coming over after lunch.

Where do you live?

 

[Krunok]

@Olli Yes, I can confirm in Acourate and Audiolense that the simulations match the measured in REW perfectly - done it over a dozen times in both programs and don't even bother any more.

Agree with the downward slope or tilt of 20 Hz to -10 db @ 20 kHz provides the most neutral response in my experiments. And seems to agree with the R&D that Floyd Toole and Sean Olive have performed, which I wrote a summary, peer reviewed by Sean Olive: The Science of Preferred Frequency Response for Headphones and Loudspeakers.

Here is the measured response of my system at the LP using default REW settings with a 500ms right window:

View attachment 22675

Aside from constant directivity horn equalization, this was taken before I used partial correction to 8 kHz. For some waveguides and compression driver combos, I find leaving the top octave alone sounds less strident, as does using a very small value (e.g. 1) for HF excess phase correction. Then the HF eq is acting more like a tone control.

Hope you have fun in your new space!

This is trully imrpessive! What kind of drivers are having response from 10Hz?
(ah ok, it's written on the graph title!)

How exactly was this measured? Sine sweep, single or average, RTA?

Btw, have you measured both speaker response?

 

[mitchco]

@Olli Here is my CPD - note I used mid-frequency correction as well and really toned down the HF excess phase correction...

@RayDunzl - would love to have to have you over, but some 3200 miles away

@Krunok - a bit more info here including pics and timing (step) response: https://www.avsforum.com/forum/113-...audio-subwoofer-thread-1223.html#post57390652

And to your other q's see my response in the other thread on Room eq's dos and don'ts. PS. I don't bother with measuring both speakers at the same time as John M, author of REW) (and other practitioners) have explained why, but my poor brain can't remember at the the moment and I can't find the link...