fore
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Post by fore on Jan 21, 2018 17:10:00 GMT -5
I've had an XMC-1 for quite awhile now. I upgraded to dual subs since xmas, SVS SB16 Ultra's. I don't understand why, under Setup/Speakers/Preset and Dirac/Size, there's not and 'OFF' option for the 'Low Pass Slope'. I have all the control of LPFreq as well as LPSlope in the SB16's setup options. It's having the LFE signal go thru 2 Low Pass Slopes no? One from the XMC-1 and one from the SB16? And 12 and 24dB slope option from the XMC-1 and fully adjustable slopes from the subs.
I have all my speakers set at Large and will be using Dirac when I get a chance. I feel like I should understand this but...lol
I appreciate the help guys,
Thanks, Fore
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geebo
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Post by geebo on Jan 21, 2018 17:24:50 GMT -5
I don't think there is a low pass for the LFE so there is nothing to turn off. The slope you're looking at is for the crossover from small speaker to subwoofer.
Correction: See Keith's post below. There is an undefeatable low pass in the XMC that's low enough to keep anything too high from getting through and high enough to not interfere with LFE content.
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Post by jmilton on Jan 21, 2018 17:34:41 GMT -5
Geebo speaks wisely.
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KeithL
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Post by KeithL on Jan 21, 2018 21:46:54 GMT -5
The LFE channel itself is full range - but is only supposed to be used for low frequency special effects. Therefore, the main purpose of the low pass filter on that channel is to "catch" anything that's there by mistake. (You WANT everthing sent to the subwoofer by the bass management to be played........ there's no reason to limit it.)
In any case, the XMC-1 does have a fixed low-pass filter on the LFE channel..... I believe it is set at 250 hz..... high enough to NOT interfere with anything else..... And it cannot be disabled or changed.
[Just for the record, it looks like I was wrong, and the frequency is actually 125 Hz or thereabouts.... KL.... 2018/01/25]
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fore
Minor Hero
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Post by fore on Jan 22, 2018 8:45:54 GMT -5
Ah, now that makes sense guys. Thanks! So I guess it'd be helpful for this 12 or 24dB slope should be grayed out if all the speakers are set to 'Large'. Good to hear KeithL that the LFE'ss LFE low pass crossover freq is set at 250hz.
Just curious then, say if I wanted to set all speakers then to 'Small'. The same question then arises. I still have to use the LFE slopes in addition to the LFE slope of the SB16s. I still think there should be an option to turn it off and have the sub do all the LFE adjustments (LFE filter on/off, LFE slope, and LFE low pass crossover freq.)
Also, may I ask, is there/or do you guys have a preference in setting up dual subs with the XMC-1?
Thanks for all the help!! Fore
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Post by localnet on Jan 22, 2018 9:44:33 GMT -5
Ah, now that makes sense guys. Thanks! So I guess it'd be helpful for this 12 or 24dB slope should be grayed out if all the speakers are set to 'Large'. Good to hear KeithL that the LFE'ss LFE low pass crossover freq is set at 250hz. Just curious then, say if I wanted to set all speakers then to 'Small'. The same question then arises. I still have to use the LFE slopes in addition to the LFE slope of the SB16s. I still think there should be an option to turn it off and have the sub do all the LFE adjustments (LFE filter on/off, LFE slope, and LFE low pass crossover freq.) Also, may I ask, is there/or do you guys have a preference in setting up dual subs with the XMC-1? Thanks for all the help!! Fore I have been out of this game for awhile, but I spoke with one of the guys over at SVS in Youngstown OH this past weekend. He told me set speakers to small, so that they do not get that low pass signal. Let the subs handle that, as speaker damage may happen. I don't know if that helps, but that was the reason I called SVS, I don't want to break anything. He also said to set the xover to 120, as that is what the SVS subs are designed for. Nothing any higher. I would call SVS, they are incredibly knowledgeable about all of this and were an immense help on a few occasions when I was having issues. Really great guys over there.
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Post by foggy1956 on Jan 22, 2018 10:20:40 GMT -5
The LFE channel itself is full range - but is only supposed to be used for low frequency special effects. Therefore, the main purpose of the low pass filter on that channel is to "catch" anything that's there by mistake. (You WANT everthing sent to the subwoofer by the bass management to be played........ there's no reason to limit it.) In any case, the XMC-1 does have a fixed low-pass filter on the LFE channel..... I believe it is set at 250 hz..... high enough to NOT interfere with anything else..... And it cannot be disabled or changed. At one time I believe you said the low pass was fixed at 110 and that seems to be what REW confirms, once again my memory is always susceptible?😊
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Post by markymiles on Jan 23, 2018 2:48:56 GMT -5
[/quote]At one time I believe you said the low pass was fixed at 110 and that seems to be what REW confirms, once again my memory is always susceptible?😊[/quote]
Nope your memory serves you well :-). It is 110 or thereabouts not 250hz. Again confirmed in REW
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geebo
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Post by geebo on Jan 23, 2018 8:02:42 GMT -5
I'll have to look at my REW traces but as I remember they go higher than 110Hz.
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Post by vneal on Jan 23, 2018 8:08:54 GMT -5
JL Audio offers both low pass filter settings on all their home subs. The 12 db works best for my room
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Post by foggy1956 on Jan 23, 2018 9:35:43 GMT -5
I'll have to look at my REW traces but as I remember they go higher than 110Hz. While the trace continues I believe you will see a 24db/octave drop around 110hz, although I haven't gone back to check.
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geebo
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Post by geebo on Jan 23, 2018 9:39:28 GMT -5
I'll have to look at my REW traces but as I remember they go higher than 110Hz. While the trace continues I believe you will see a 24db/octave drop around 110hz, although I haven't gone back to check. I'll try to remember to look tonight. We'll see...
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Deleted
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Post by Deleted on Jan 23, 2018 10:13:15 GMT -5
Sorry Keith and others if I'm wrong since there have apparently been some changes by some music recording engineer who now use the LFE channel as full range. I might not be up on the latest on the LFE.
However the original intent of the Dolby LFE (low freqiency Effects channel which was the .1 in the 5.1 movie recording) channel was not full range. There is full range bass in the 5+ channels but they are not intended to be at the increased 10 dB level of the LFE signals. If the 5+ main speakers are full range then the user can decide if and what frequency level to cut off the low bass and send it to the sub. If any or all of the 5+ speakers are not full range then the user can send the bass signal below 80Hz or so as desired to the sub. The LFE channel also was not intended to be used as a "subwoofer" channel but to be combined with the low bass signals which were redirected from the main 5+ channels and sent to the sub. Many new pre-pro's have prostituted the LFE signal bass management routes not originally intended by Dobly. The sub(s) are for reproducing both the low bass from the mains and combined with the LFE .1 signal. Many brands of receivers/pre-pros have screwed this up!
The LFE channel is suppose to be recorded with a rather steep roll off above 80Hz and a brick wall cliff at 120Hz. Zero LFE signal above 120Hz.
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geebo
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Post by geebo on Jan 23, 2018 10:29:45 GMT -5
I'll have to look at my REW traces but as I remember they go higher than 110Hz. While the trace continues I believe you will see a 24db/octave drop around 110hz, although I haven't gone back to check. Here is a post by ansat some time ago. The blue trace in the top graph is the LFE output. emotivalounge.proboards.com/post/736529
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Post by markymiles on Jan 23, 2018 10:36:53 GMT -5
I've got loads of REW plots at home. When using HDMI Channel 4 (ASIO4ALL drivers) you get a roll off as stated around 110hz with either a 12db slope or 24db slope depending on what you set the LPF value in the XMC.
Other AVRs/Pros allow you to adjust this roll off value but the XMC is set at this value. As has already been stated for the LFE channel there shouldn't be any content above 120hz anyway.
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geebo
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Post by geebo on Jan 23, 2018 10:54:40 GMT -5
I've got loads of REW plots at home. When using HDMI Channel 4 (ASIO4ALL drivers) you get a roll off as stated around 110hz with either a 12db slope or 24db slope depending on what you set the LPF value in the XMC. Other AVRs/Pros allow you to adjust this roll off value but the XMC is set at this value. As has already been stated for the LFE channel there shouldn't be any content above 120hz anyway. Tony's trace was done using no mic or speaker so there is no subwoofer rolloff and no room effects included. It clearly goes out to 200Hz and beyond. Looks to be 12dB/octave.
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Post by millst on Jan 23, 2018 11:19:33 GMT -5
Dolby said one thing, but content producers did not always follow it. [Consequently?] Makers of receivers/pre-pros rarely use the brick wall either. At least you have some control with the XMX-1. It's a tradeoff of "losing" content versus sub localization.
-tm
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Post by foggy1956 on Jan 23, 2018 11:38:46 GMT -5
While the trace continues I believe you will see a 24db/octave drop around 110hz, although I haven't gone back to check. Here is a post by ansat some time ago. The blue trace in the top graph is the LFE output. emotivalounge.proboards.com/post/736529So you're seeing the break at 250 on that trace then?
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geebo
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Post by geebo on Jan 23, 2018 11:44:14 GMT -5
So you're seeing the break at 250 on that trace then? I'd say it's very close to being down 3dB at 240Hz with a 12dB/octave slope. Wouldn't you?
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Post by foggy1956 on Jan 23, 2018 12:23:38 GMT -5
So you're seeing the break at 250 on that trace then? I'd say it's very close to being down 3dB at 240Hz with a 12dB/octave slope. Wouldn't you? just a guess but looks like anything beyond about 170hz has anything to do with actual lfe signal
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