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post #2971 of 2991 Old 04-17-2015, 12:03 PM
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Quote:
Originally Posted by Stereodude View Post
I'm suggesting they make an in between product that's well suited for subwoofer usage that isn't $500.
I don't disagree with the importance of knowing the limits of your system but I'm curious as to why you don't just turn the trims down? are you getting too much noise if you do or can't turn it down far enough? or something else maybe?
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post #2972 of 2991 Old 04-17-2015, 12:25 PM
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Originally Posted by 3ll3d00d View Post
I don't disagree with the importance of knowing the limits of your system but I'm curious as to why you don't just turn the trims down? are you getting too much noise if you do or can't turn it down far enough? or something else maybe?
With my Pioneer Elite SC05 I could just barely get the output voltage below the clipping point of the balanced 2x4 by turning the sub trim down to -10dB (lowest it would go) to support 0dB / "reference" level playback of worst case 5.1 content. However, any EQ boost in the miniDSP would result in clipping the output of the miniDSP. That can be mitigated by turning down the input level in the miniDSP GUI. Then I had to turn up the gain on my amps all the way so the 75dB test tone was the right volume. So, yes, I was able to make it work, but the user has to be very cognizant of exactly what needs to be done and it's not something a n00b is going to stumble into. In it's current incarnation it's certainly not a plug & play / can't mess it up subwoofer EQ.
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post #2973 of 2991 Old 04-17-2015, 12:29 PM
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Originally Posted by Stereodude View Post
Why thank you. Yes, I am trying to be cheap about it. I'm suggesting they make an in between product that's well suited for subwoofer usage that isn't $500.
First, the subwoofers only clip in case of a not-gonna-happen scenario you imagined and/or completely inept system setup.

What you fail to understand is, to get the upper bass really right in a small room one actually needs the 8x8/10x10 (“8x8” for the rest of this post) unit’s capabilities anyway. (Or the 2x8/4x10 with an upstream A/D converter.) This has nothing to do with picayune complaints that a very inexpensive box can’t handle massive and not-seen-in-a-competently-set-up-system input levels. Rather, it’s the matrix routing feature that’s key.

Bass management is always handled ineptly by AVRs and prepros, and the errors are readily unmasked in competently set-up multisub installations, because the overall response is much smoother. Also, common setups put a “crossover” right in the middle of the modal region (i.e. ca 80Hz) which is just a stupid thing to do.

The way around the stupidity of onboard bass management is defeat it entirely for the mains and feed the LCR+LFE preouts to the 8x8. (One can also, of course, add the side surrounds to that, depending on how many subs one is running.) Sum all the bass from the front three channels and the LFE for the subwoofers. Apply highpass filters to your mains if you must, i.e. if they’re compromised designs (fairly small, vented, etc.), but otherwise let them run fullrange. Optimize according to your priorities (seat-seat consistency, listening position FR, whatever) using measurements.

As the 2x4 doesn’t have 4 inputs (for LCR+LFE) or enough outputs for LCR + multisubs, it’s suboptimal for serious subwoofer setups to begin with. It’s great for multiway mains, though. And would be better if they fixed its only real flaw (the turn on/off thump).

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post #2974 of 2991 Old 04-17-2015, 12:30 PM
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Quote:
Originally Posted by Stereodude View Post
With my Pioneer Elite SC05 I could just barely get the output voltage below the clipping point of the balanced 2x4 by turning the sub trim down to -10dB (lowest it would go) to support 0dB / "reference" level playback of worst case 5.1 content. However, any EQ boost in the miniDSP would result in clipping the output of the miniDSP. That can be mitigated by turning down the input level in the miniDSP GUI. Then I had to turn up the gain on my amps all the way so the 75dB test tone was the right volume. So, yes, I was able to make it work, but the user has to be very cognizant of exactly what needs to be done and it's not something a n00b is going to stumble into. In it's current incarnation it's certainly not a plug & play / can't mess it up subwoofer EQ.
Few units rarely are. You can argue something like the old ED eq.2 is foolproof, but just about any robust EQ setup can be botched. I know Bosso was speaking of several occassions where he saw folks using the bassis units with upwards of 18dB shelving and frying drivers, amps, and everything left and right, having no clue why it was happening. EQ is a fickle beast, you gotta definitely be "Cognizant" to say the least...

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post #2975 of 2991 Old 04-17-2015, 12:49 PM
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Quote:
Originally Posted by DS-21 View Post
Bass management is always handled ineptly by AVRs and prepros, and the errors are readily unmasked in competently set-up multisub installations, because the overall response is much smoother. Also, common setups put a “crossover” right in the middle of the modal region (i.e. ca 80Hz) which is just a stupid thing to do.
Just as a matter of curiosity, how high are you able to set the LPFs of the subs before you notice localization? Are they 4th-order LPFs?
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post #2976 of 2991 Old 04-17-2015, 03:16 PM
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Never paid any attention to this very much. But after reading Bosso's post on another forum concerning Interstellar's soundtrack, I checked my inputs. I'm using the UnBal 2x4 with whatever the jumper comes set at factory. At -10 to -8db the input clips with the 2:18min content. I haven't metered the voltage out of the preamp yet except with a -20db@50hz tone which hit 0.9v at a MV of +3db. I can't remember if Audyssey was on or off. My current amps are rated for full power@1.0v. I assume moving the jumper being moved to the 2.0v tap would give me additional headroom on the preamp side?
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post #2977 of 2991 Old 04-17-2015, 04:11 PM
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^
From the updated manual PDF file, page 37:
Quote:
Note that the input sensitivity jumper setting does not affect the maximum output signal – it is always 0.9 V RMS. Therefore, when the jumper is in the 2.0 V position, the miniDSP (without any other processing enabled) has an approximately 7 dB insertion loss. If higher output signal levels are required, then the miniDSP Balanced 2x4 or the 4x10 Hd can be used.
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post #2978 of 2991 Old Yesterday, 11:09 AM
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Okay, time for a small piece of crow. If you have a Denon, or at least a 4520CI, you don't need to worry about the balanced 2x4 MiniDSP input clipping because the 4520CI subwoofer output clips just before the miniDSP will clip the input. This is a -0.01dBFS 40Hz signal encoded into the LFE channel of a 5.1 DTS file with the MV at 0dB. The 5 main channels are silent. Before making any measurements I turned off Audyssey, set all the speaker & sub trims to 0dB, and set all the speakers to the same distance.



Dialing back the master volume to -1dB eliminates the clipping.



I can also confirm that the meters with the v1.10 2 way advanced are now effectively peak readings, not RMS. The unit clips at 0dB on the internal meters. The level meters in the GUI are also now actually dB.

With that signal from the Denon fed into the balanced 2x4 MiniDSP (via an unbalanced connection) the input levels show this:



The output levels for the same signal (no filters active):

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post #2979 of 2991 Old Yesterday, 03:55 PM
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Good to know. That is the exact avr that I am using. I have used it with yamaha's and other Denons too without issues. Thanks for taking the time to do the test.
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post #2980 of 2991 Old Yesterday, 05:16 PM
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Quote:
Originally Posted by andyc56 View Post
Just as a matter of curiosity, how high are you able to set the LPFs of the subs before you notice localization? Are they 4th-order LPFs?
I can't really answer that as I haven't tried to push things high enough to get localization problems. But I don't have localization issues - once I added some blu-tack to the back of the lightswitch plate near the nearfield sub, at least! - with the following settings (IIRC):
left and right subs highpassed at 160ish Hz, 2nd order,
corner sub highpassed at 120Hz, 4th order but with some odd EQ from 100-120Hz that helps smooth out the system response,
the nearfield sub highpassed at 90Hz, 4th order.

Electrical slopes are basically the electrical slopes, because the drive-units I use are pretty good up to above 1kHz.

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post #2981 of 2991 Old Yesterday, 05:50 PM
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Thanks!
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post #2982 of 2991 Old Yesterday, 06:24 PM
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Quote:
Originally Posted by Pain Infliction View Post
Good to know. That is the exact avr that I am using. I have used it with yamaha's and other Denons too without issues. Thanks for taking the time to do the test.
Well my post wasn't to imply everything was rosy. It's just that the 4520CI clips just before the balanced 2x4 miniDSP does. The problem there is that the 4520CI clips with the SW trim at 0 and the MV at Reference (0) with only a full amplitude LFE signal (no bass redirection going on). So, if you want to listen at reference with your 4520CI you'd better have your SW trim set no higher than -5dB (to allow for some bass management + full amplitude LFE). If you want to push beyond reference for every dB above reference you want to go, you'd need to take a dB off the SW trim and make it up for it on your sub amp's gain. Unfortunately, you're limited to -12dB on the SW trim, so that means if you want to run demos above +7dB you're probably going to get some clipping from the 4520CI on the LFE channel(s).
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post #2983 of 2991 Old Yesterday, 07:59 PM
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I didn't know that about the 4520. I am still in the clear though because my sub trim is way down to -6.5 or so. I like to turn the amp gains up more than turning up anything else in the chain, as it should be that way anyway. I also don't watch at reference levels or near it.

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post #2984 of 2991 Old Today, 01:15 AM
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Anomalies with high pass filters | miniDSP 4x10 HD w/96kHz and 48kHz plugin

Measured miniDSP 4x10 HD using REW with the 96kHz and 48kHz plugins. The calibration was done with miniDSP in the chain. It was hooked up by running digital out of soundcard into miniDSP 4x10 HD, then analog out of miniDSP into the soundcard.

Be very careful with high pass filters in the low region as they overshoot A LOT.

96kHz plugin

These are all the stock filters at set at 10 Hz and 3kHz. The behavior is normal at 3kHz, but as you approach the minimum limit of 10Hz you get overshoots upwards of +13dB @ ~12Hz for the BW 48dB/oct filters.



48kHz plugin (commonly used with 10x10 HD)

Notice that the overshoot with the 48kHz plugin is not that severe as with the 96kHz one. The maximum overshoot is approx +3dB @ ~12Hz.


96kHz plugin, BW 48dB/oct HPF @ {10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100} Hz


48kHz plugin, BW 48dB/oct HPF @ {10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100} Hz


These anomalies are also visible through each channel's output monitor. For example, if you use the signal generator in REW and set it to 12 Hz -20dBFS and watch the monitoring scale with the filter off and on you will see that it overshoots. Remember not to have anything connected while trying as you could obviously damage your speaker. This is an example with the 96kHz plugin:

No high pass filter


With BW 48dB/oct high pass filter @ 10 Hz.


The PEQ filters are also very unstable in the 10-30hz region, so be careful with the filters and measure what you're actually doing or use the 48kHz plugin as it doesn't overshoot by so much.

DAC/Preamp: miniDSP 4x10 HD
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Amplifiers: Emotiva XPR-1, Denon POA 1500, QSC GX5 and Sanway's LabGruppen FP14000 clone
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post #2985 of 2991 Old Today, 05:01 AM
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Did you try using manually entered advanced biquad filters to see if it behaved any differently? You would need to stack 4 of them to get a 48dB Butterworth filter.
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post #2986 of 2991 Old Today, 05:38 AM
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Quote:
Originally Posted by Stereodude View Post
Did you try using manually entered advanced biquad filters to see if it behaved any differently? You would need to stack 4 of them to get a 48dB Butterworth filter.
Tried, but don't get the expected results in the plugin GUI.

Stacked four of these


using this

Code:
biquad1,
b0=0.999537306769479,
b1=-1.999074613538960,
b2=0.999537306769479,
a0=1,
a1=1.999074399453920,
a2=-0.999074827623995,
biquad2,
b0=0.999537306769479,
b1=-1.999074613538960,
b2=0.999537306769479,
a0=1,
a1=1.999074399453920,
a2=-0.999074827623995,
biquad3,
b0=0.999537306769479,
b1=-1.999074613538960,
b2=0.999537306769479,
a0=1,
a1=1.999074399453920,
a2=-0.999074827623995,
biquad4,
b0=0.999537306769479,
b1=-1.999074613538960,
b2=0.999537306769479,
a0=1,
a1=1.999074399453920,
a2=-0.999074827623995,
biquad5,
b0=1,
b1=0,
b2=0,
a1=0,
a2=0,
biquad6,
b0=1,
b1=0,
b2=0,
a1=0,
a2=0,
biquad7,
b0=1,
b1=0,
b2=0,
a1=0,
a2=0,
biquad8,
b0=1,
b1=0,
b2=0,
a1=0,
a2=0,
which yielded this



That doesn't look right, as the stock filters look like this



If you'll advice I'll measure it asap.

DAC/Preamp: miniDSP 4x10 HD
Speakers: JBL 4343B, JBL 4430 and JBL 120Ti
Amplifiers: Emotiva XPR-1, Denon POA 1500, QSC GX5 and Sanway's LabGruppen FP14000 clone
Midbass modules: 4x DIY JBL 2226
Sub: 4x DIY LMS Ultra 5400
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post #2987 of 2991 Old Today, 05:57 AM
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I think I figured it out, I've got to cascade filters with different Q's. Will post measurements soon.

DAC/Preamp: miniDSP 4x10 HD
Speakers: JBL 4343B, JBL 4430 and JBL 120Ti
Amplifiers: Emotiva XPR-1, Denon POA 1500, QSC GX5 and Sanway's LabGruppen FP14000 clone
Midbass modules: 4x DIY JBL 2226
Sub: 4x DIY LMS Ultra 5400
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post #2988 of 2991 Unread Today, 07:17 AM
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quick question to you guys. Let's say that you have a MiniDSP unit and want to determine the output voltage on your AVR's subwoofer preout in order to ensure that you are not clipping the input of the MiniDsp, or, as in my case, (I have an iNuke3000dsp), I need to ensure that I don't clip the input on my amp (no MiniDsp).

Would it be possible to figure out the AVR's subwoofer preout voltage by using a multimeter with the leads touching the RCA connector? I was thinking of using my multimeter to figure out what the output voltage is at different settings on the sub trim with the main volume at reference. Would this work, and if so, how would you situate the leads from the multimeter to get an accurate reading?
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post #2989 of 2991 Unread Today, 08:39 AM
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Quote:
Originally Posted by GizzeGutten View Post
I think I figured it out, I've got to cascade filters with different Q's. Will post measurements soon.
Yes, you're correct. The Q is not .707 when stacking them. For a 4th order the two Q values are 0.5412 and 1.3065. I'm not sure what they are for a 8th order though.

Edit: Page 9 of this PDF from TI lists them.
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post #2990 of 2991 Unread Today, 08:51 AM
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Quote:
Originally Posted by Tip24/96 View Post
quick question to you guys. Let's say that you have a MiniDSP unit and want to determine the output voltage on your AVR's subwoofer preout in order to ensure that you are not clipping the input of the MiniDsp, or, as in my case, (I have an iNuke3000dsp), I need to ensure that I don't clip the input on my amp (no MiniDsp).

Would it be possible to figure out the AVR's subwoofer preout voltage by using a multimeter with the leads touching the RCA connector? I was thinking of using my multimeter to figure out what the output voltage is at different settings on the sub trim with the main volume at reference. Would this work, and if so, how would you situate the leads from the multimeter to get an accurate reading?
A MultiMeter can be used to measure output voltages. Some DMM's are more accurate than others, but for casual measurements, an inexpensive DMM will work. Make sure you set the DMM to measure AC, and not DC. Touch the leads to the center conductor and the outer grounding shell. if you reverse the leads, the voltage will read a negative value, which is OK.

Of course, you need to provide the appropriate signal to measure. You will hear various opinions on how to provide a signal, including playing clips from movies with strong LFE content at reference levels (e.g. WOTW pod emergence). Stereodude has a downloadable DTS test tone file that is referenced in a previous post that may be useful. In my case, use REW' signal generator to output a 50Hz sine wave at -3dBFS (REW max). The AVR has bass management turned on, crossovers at 80Hz, sub trim at zero, room correction off, and master volume at unity. I recommend muting or powering off all speakers while running voltage tests. And you can gradually increase MV beyond unity to explore maximum output voltage from the AVR.
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post #2991 of 2991 Unread Today, 09:18 AM
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Quote:
Originally Posted by Tip24/96 View Post
quick question to you guys. Let's say that you have a MiniDSP unit and want to determine the output voltage on your AVR's subwoofer preout in order to ensure that you are not clipping the input of the MiniDsp, or, as in my case, (I have an iNuke3000dsp), I need to ensure that I don't clip the input on my amp (no MiniDsp).

Would it be possible to figure out the AVR's subwoofer preout voltage by using a multimeter with the leads touching the RCA connector? I was thinking of using my multimeter to figure out what the output voltage is at different settings on the sub trim with the main volume at reference. Would this work, and if so, how would you situate the leads from the multimeter to get an accurate reading?
You need a True RMS meter and you can't directly check for clipping with it. You have to record the voltage at various volume settings and calculate the voltage gain in dB. When the expected voltage gain doesn't match the actual output gain, you have clipping. You end up with something like this:



At 4.5dB and above the output gain is not as expected, so you can tell it's clipping.
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