Advice on FIR Filters with Audiolense XO and Setup Considerations

HI,

The umic in combination with USB dacs quite often leads to glitches in the measurements, which leads to timing errors in the measured impulses. The response will be good enough for a frequency response, also with crossovers included.. The image may be slightly off-centered, but this can be tweaked back manually. However, the timing errors often ruin the prospect of a good sounding time domain correction. So you may have to need a better microphone to get something that is good enough for TTD correction. But try before you buy.

You will get a set of 8 individual filters from Audiolense too, more if subwoofers are included. And you will get a plug & play zip file that loads directly into Roon, with filters, channel routing and all.

Audiolense correct each driver individually, but it does so based on the sweet spot meassurement. A global correction (the whole speaker) is the last step in the procedure and is applied to all the driver corrections.The approach with combining nearfield correction with sweet spot correction is not supported by Audiolense and also an approach I advise against. Sometimes you will get the same result, other times an inferior result. If you do a full range correction using the two-step approach you will get the same result, since the sweet spot correction will completely reshape the nearfield correction. In reality, all you do is to alter the measurement signal used for the sweet spot correction. The first step (the nearfield correction) modifies the signal on it's way to the speaper and the second stage accounts for this modification.

With digital crossovers and only global correction from the sweet spot: The best thing that can happen is that you get virtually the same result in the sweet spot as you do from correcting everything based on sweet spot measurement. The most normal thing that will happen is that the overall result will be practically the same in the sweet spot, but the driver interaction will be slightly less perfect than it could have been.

At certain frequencies, most prominent in the Schroeder region where the speakers start to decouple from the room, the drivers including early reflections will display a different frequency and time behavior in the sweet spot than in the near field. Higher up in frequency, diffractions from driver edges, cabinet edges etc will have a different relative time delay and possibly magnitude between the two measurement positions. And lastly, the distance differences between the drivers will be different in the sweet spot than in the nearfield.

The worst that can happen is this: You make perfect crossover between a woofer and a midrange driver from nearfiield as part of a "perfect" nearfield correction. The crossover happens to overlap with the Schroeder region, where influences from boundary reflections are the most problematic. Then it turns out that the sonic interaction with the floor and ceiling is such that the two "perfectly integrated" drivers ... at some overlapping frequency ... in the sweet spot ... are out of phase with each other. You have "hardcoded" a cancellation between the two drivers. This could have been avoided if you had omitted the nearfield correction.

Correction philosophies aside, Audiolense is very tunable with regards to how much room influence is accounted for, etc. So you do not have to agree with me on the philosophy to achieve a result to your likings.

In the end, it's your opinion of the end result in your room that matters. A purchase comes with a 3 month satisfaction guarantee. You are entitled to claim a full refund if you within 3 months decide that you're better off without Audolense than with it, for whatever reason. It is called upon once in a while, so this is for real. But it doesn't happen very often since most who go down this road manage to dial in a sound that they really enjoy, and quite regularly achieve a sound quality that by far exceeds what they were hoping for.

Welcome to the forum btw!