Parallel Sub Configuration / Simulation Question

[Ofer]

First of all, if it sounds good this is all that matters. None the less it is a bit perplexing. On the lower end there are all kinds of room interactions so I am not surprised that your mains don't really role of at 55hz. On the higher xo it is weird. The LFE is supposed to be cut at 150hz but it rolls of much later something like 350hz. The cross-over is defined in a somewhat unconventional way in AL. It is octave and not the usual Linkwitz Riley 12-96db/octave nomenclature. None the less a 2 octave slope should have been much steeper then what we see in the measurments. See below my system. Both the mains and sub are crossed at 30hz, but the mains being ported or for whatever reason behave differently. The sub is cut at 120hz (marked by the cursor). It starts rolling of later at 144hz but that is expected, still not 200hz later. miniDSP provides 5 filters/channel and no TTD AL provides hundreds in no thousands of filters...

 

[whoareyou]

Hi Whoareyou,
You wrote " Also, anyone have success with measuring a multichannel setup via JRiver / REW /USB DAC / USB mik (umik-1)? "

I'm running JRiver -> exaSound 8channel DAC-> pre+power amp to main speakers and 2 more outputs from the DAC to 2 subwoofers. So, 4 channels in total. I use the Dayton Audio UMM-6 mic with Audiolense, and also own the Dayton Audio OmniMic measurement mic+software.

I was noticing how much filter insertion loss your target curve was experiencing and wonder if there's a way to reduce it, somewhat? Do you use the correction filters to try and align the volumes of all your amps (e.g. gain matching)? I'm assuming you use an amp for your main and side speakers, and separate amps for each sub? I found that if one amp shows a higher correction filter than the other amps then this adds filter insertion loss. If this higher correction is very near a XO point then I'd play around with XO frequency and slope width to see if it'd reduce OR turn up the volume on the amp that is related to the higher correction. The correction filters are like a teeter-totter found at the kid's playground - turning up the vol on one amp causes the other amp's volume to fall because the Y-axis is a relative measurement and not an absolute measurement. Try and get the teeter-totter horizontal, so to speak . . .

One 5 channel amp and a 2 channel, and they are fairly close in gain after I match them. Some of the loss is due to my 14DB filter correction, but I am not concerned about it as I can make up quite a bit of it in JRiver without clipping, and I have enough headroom to play as loud as need be. Without correction filters you can't really tell where the "loss" is, but moving crossover around a bit might reduce the loss. But like I've said, I'm going by what system sounds like, and my XO's sound good to me.

Really, what my room needs is more treatment to reduce the bass swings.

And, I can playback just fine via JRiver with my exasound e38. I just can't measure through jriver. If you can do that, I'd like to know how.

 

[kevinzoe]

Whoareyou - How do you make up quite a bit of it in JRiver?

When using AL XO I am not running JRiver.

 

[whoareyou]

Whoareyou - How do you make up quite a bit of it in JRiver?

When using AL XO I am not running JRiver.

Parametric equalizer allows channel by channel adjustment

 

[whoareyou]

First of all, if it sounds good this is all that matters. None the less it is a bit perplexing. On the lower end there are all kinds of room interactions so I am not surprised that your mains don't really role of at 55hz. On the higher xo it is weird. The LFE is supposed to be cut at 150hz but it rolls of much later something like 350hz. The cross-over is defined in a somewhat unconventional way in AL. It is octave and not the usual Linkwitz Riley 12-96db/octave nomenclature. None the less a 2 octave slope should have been much steeper then what we see in the measurments. See below my system. Both the mains and sub are crossed at 30hz, but the mains being ported or for whatever reason behave differently. The sub is cut at 120hz (marked by the cursor). It starts rolling of later at 144hz but that is expected, still not 200hz later. miniDSP provides 5 filters/channel and no TTD AL provides hundreds in no thousands of filters...

Not sure what to say except what AL does is very different from miniDSP. As I mentioned earlier, only way you'll know if AL works for you is to give it a good workout, get used to the simulations and how everything else works. Help file explains some of this stuff i.e. how Bernt implemented the XOs.
I still have plenty to learn so you should really take anything I say with grain of salt.

 

[whoareyou]

Hi Whoareyou,
You wrote " Also, anyone have success with measuring a multichannel setup via JRiver / REW /USB DAC / USB mik (umik-1)? "

I'm running JRiver -> exaSound 8channel DAC-> pre+power amp to main speakers and 2 more outputs from the DAC to 2 subwoofers. So, 4 channels in total. I use the Dayton Audio UMM-6 mic with Audiolense, and also own the Dayton Audio OmniMic measurement mic+software.

I was noticing how much filter insertion loss your target curve was experiencing and wonder if there's a way to reduce it, somewhat? Do you use the correction filters to try and align the volumes of all your amps (e.g. gain matching)? I'm assuming you use an amp for your main and side speakers, and separate amps for each sub? I found that if one amp shows a higher correction filter than the other amps then this adds filter insertion loss. If this higher correction is very near a XO point then I'd play around with XO frequency and slope width to see if it'd reduce OR turn up the volume on the amp that is related to the higher correction. The correction filters are like a teeter-totter found at the kid's playground - turning up the vol on one amp causes the other amp's volume to fall because the Y-axis is a relative measurement and not an absolute measurement. Try and get the teeter-totter horizontal, so to speak . . .

I do not use AL for matching gain. I level match my speakers before measuring, but bass frequencies have large variations due to the room. And that's (part of reason) I use AL.

As you mentioned, moving XO's around help / hurt depending on selection and I don't feel that any of my sub's XO points are optimal, but I still think the results are very good.

If I raise levels of subs then levels of some frequencies are pushed way to high, and others are *still* too low. It just moves around my problem. Plus, some of the raised bass frequencies will cause clipping during measurements.

 

[juicehifi]

First of all, if it sounds good this is all that matters. None the less it is a bit perplexing. On the lower end there are all kinds of room interactions so I am not surprised that your mains don't really role of at 55hz. On the higher xo it is weird. The LFE is supposed to be cut at 150hz but it rolls of much later something like 350hz. The cross-over is defined in a somewhat unconventional way in AL. It is octave and not the usual Linkwitz Riley 12-96db/octave nomenclature. None the less a 2 octave slope should have been much steeper then what we see in the measurments. See below my system. Both the mains and sub are crossed at 30hz, but the mains being ported or for whatever reason behave differently. The sub is cut at 120hz (marked by the cursor). It starts rolling of later at 144hz but that is expected, still not 200hz later. miniDSP provides 5 filters/channel and no TTD AL provides hundreds in no thousands of filters...View attachment 52234

Is this measured with correction engaged? How did you correct? It does not look like a typical correction.

 

[Ofer]

Well I have a miniDSP that allows for 5 (IIR) filters on each output and input. I used the filters on the outputs to linearize the drivers using near field measurements. That left 5 filters for each input i.e. left and right whole range. That is why I am so interested in AL that can created thousands of filters of all sorts.