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Anthem ARC Genesis - Crossover Slopes

ad_fletch

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Hello Experts,

I was reading about crossover slope adjustment in the recent Onkyo TX-RZ50 review, and I thought I would play with the slopes in ARC Genesis, with which I have only just started experimenting.

I changed the adjustable slopes to 4th order LR filters, because I like the idea of in-phase, flat-summing crossovers. However, I got no bass that way, which confused me at first.

Turning to this online guide from Anthem, I realised that the slopes can only be set for high-pass filters and not the whole crossover - here is the relevant extract:

Screenshot 2022-02-23 144302.png


So my question is, why can't I have a 4th order crossover from my mains to my subwoofer? I'm sure there's a good reason, but I was a bit disappointed to find I only had the illusion of control over the crossover slopes.

I actually had a 24dB crossover using an Allo Piano 2.1 DAC before I got the Anthem, so I know it works with the speakers I have. I have also found some guidance (eg from Rhythmik Audio) which suggests I'd be better off with a steeper slope on the HPF for the mains. In terms of alternative phase correction using delays, I'm going to have to wait until the house is quiet to do some investigating with REW I guess.

Don't get me wrong - I'm still enjoying having heaps more control than many other room correction systems, I'm just seeking to understand this limitation.
 

Head_Unit

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I realised that the slopes can only be set for high-pass filters and not the whole crossover - here is the relevant extract:
Ah, it seems like if you set the bass to go to the sub you can't set the high-pass slope at all? It's only 12 dB?
 
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ad_fletch

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Yep, that appears to be the case, unless I'm missing something.
 

GalZohar

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I don't think you're missing something, Gene from Audioholics also made a video that mentioned this limitation. Both subwoofer and speakers can only be crossed at 12db/oct. Supposedly Anthem told him they will add other options in a firmware update at some point...
 
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ad_fletch

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Seems really odd that they'd let us control the slope, but not when crossed over. Also, 12dB slope on the sub LPF is not even industry standard. Just really curious. Also, the latest firmware on Anthem's site for my AVR (MRX 310) is dated April 2015, so don't suppose I should hold my breath for that update. Wonder whether it could be done in Genesis alone....
 
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ad_fletch

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OK so I did some more digging, and it turns out this was explored pretty extensively by Dr David Rich in 2013 on Secrets of HT and Hi-fi.

If I understand it correctly, he found that ARC does indeed set the xo slope at 12dB, but then uses EQ filters to achieve 24dB acoustic slopes in the final result. Should have known it was all by design....
 

GalZohar

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OK so I did some more digging, and it turns out this was explored pretty extensively by Dr David Rich in 2013 on Secrets of HT and Hi-fi.

If I understand it correctly, he found that ARC does indeed set the xo slope at 12dB, but then uses EQ filters to achieve 24dB acoustic slopes in the final result. Should have known it was all by design....

So the 12/db octave shown in the graph slope is on top of the crossover's 12db/octave not shown in the graphs? I guess Anthem owners can easily verify this by measuring with subwoofer turned off and then again with speakers disconnected?
 

gbrnole

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the most recent ARC software definitely sets auto slopes steeper than 2nd order (12 db octave). i have an MRX 1120 and what is shown in the video clip linked below is consistent with my results when i want to go in and make changes after ARC has been run. if you look in the video (beginning timestamp 3:02) you will see that the slope of the front speakers has been automatically set to 4th order (24 db octave).


as you correctly point out though it is annoying that if you override that slope it doesn't redirect bass to the subs. i believe anthem's intent here was for people with true full range speakers. a bit odd really. the receiver packs a decent punch in the power department but it can only do so much, especially when driving more than a stereo pair.

with that said i'm quite happy with the auto slopes it sets and get better results from tinkering with the crossover points and the time alignment for my subs to get the best possible blend between the subs and the mains. relatively speaking the subs should really already be positioned in their best spots to avoid nulls and dialed in with DSP (if available) before ARC is ever run.

ARC does a good job on the bottom end by itself but there is more to be gained if you have a minidsp or similar in the mix to really eek out the most. for people with 20 series receivers or older like myself it's necessary really if you are running more than one sub since ARC in this generation only factors for a single sub. the newer generation (the MRX 1140 at least) will factor for multiple subs.
 
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ad_fletch

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So the 12/db octave shown in the graph slope is on top of the crossover's 12db/octave not shown in the graphs? I guess Anthem owners can easily verify this by measuring with subwoofer turned off and then again with speakers disconnected?

Seems as though multiple users (Dr Rich and @gbrnole among them) have done just that. I don’t often get a quiet house for measuring, but looking forward to doing same myself.

Might save some head-scratching if Anthem documented this a bit better….
 

Beershaun

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Audioholics measured this and have posted a video about it. Apparently there is a new firmware update coming allowing the subwoofer low pass crossover slope at 24db/octave.

 

GalZohar

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Did they actually measure with crossover active without the firmware update? To see if it's really 12db/oct or 12db/oct from filters and additional 12db/oct from receiver's crossover for 24db/oct total? I don't think they did, or at least I couldn't find it.
 
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ad_fletch

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Thanks @Beershaun.

@Galz yes, sounds like only way to know whether it's a real change or just more obvious way for the user to make 24dB slopes.

Edit: Watched bass management section of video. Seems it requires firmware update and only changes the slope on the LPF. Would be much better if it were in ARC Genesis and controllable so users with older receivers and different speakers could benefit.

Then again i remeasured with ARC yesterday and I'm pretty happy with the sub integration now. Sadly didn't have enough time for REW checks. One day.
 
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