MiniDSP Sub Setup

[JStewart]

Currently have have Audyssey turned off and have changed the distance measurements (laser measure)

Since you didn't mention the subs specifically I'll add that even with only 1 sub the actual physical distance setting is not likely to be the correct one. Of course with 3 subs a physical measure can't apply. For something quick that will likely get very close, re-run Audyssey and use what it gets for the sub distance. A more accurate method is to phase align the sub(s) to the mains at the xo and confirm the response with REW which may be a project for another time.

 

[BigDan79]

Duct tape? Just kidding!

That Rythmik is an awesome sub. It has output much lower than the approx 23Hz the Paradigms roll off sharply at in your measurements.

One of the 2 Paradigms actually had a really good response over its output range for each of the seats without any eq:

View attachment 27964

That rise in the response from 100Hz to 25Hz is also good. A built in house curve if you will.

Further, the similarity between the 3 seats suggests that PEQ alone would work in this case to adjust the response of the sub without making the response worse for any of the seats as can happen.

Digging in further, here's what REW calculates when you put the 2 Paradigms together at the middle seat without any delay/phase adjustment between the 2 subs.

View attachment 27966


The combined output is actually lower for the two together over a good portion of the range. Where the combined output is higher (25Hz) it's undesirable. This would be a case where the one sub would have performed (more output) and sounded (smoother response) better than the 2 together. (When you mentioned that it sounded boomy it made me think of that 15dB peak at 25Hz)

Anyway, my actual thought is that since the Paradigms might also be degrading the performance of the Rythmik below 25Hz and because the output of the 1 Paradigm in its present location was good, I'd try putting the Rythmik in it's place and measure it. If the response is still good then maybe a couple of PEQ filters and/or run Audyssey and watch a movie with some deep output and see how it sounds. If it measures and sounds good and your windows still rattle then you might have some gear you can sell. Just a thought.

If you try this I'd recommend some painters tape placed so the Rythmik and Paradigm can be put back EXACTLY where they were. Also take note of the EXACT position of the volume control on the Rythmik before its changed. This way the subs can be put back without having to re-do EVERYTHING.

Interesting info. Prior to adding the Rythmik I just had the two Paradigm subs up front in a position that looked good. After adding the Rythmik and doing research I moved the subs to the corners of the room. One Paradigm front left, Rythmik front right and the other Paradigm rear right. I placed them based sound from the Audyssey correction prior to the addition of the MiniDSP. So which Paradigm sub should I switch with the Rythmik Sub 1 or 2? 1 is front 2 is rear.

 

[BigDan79]

Since you didn't mention the subs specifically I'll add that even with only 1 sub the actual physical distance setting is not likely to be the correct one. Of course with 3 subs a physical measure can't apply. For something quick that will likely get very close, re-run Audyssey and use what it gets for the sub distance. A more accurate method is to phase align the sub(s) to the mains at the xo and confirm the response with REW which may be a project for another time.

I have only one sub output to the MiniDSP and I just guested a distance for it. I can re run Audyssey for that distance as you mentioned until I get a chance to do it with REW.

 

[JStewart]

So which Paradigm sub should I switch with the Rythmik Sub 1 or 2? 1 is front 2 is rear.

The data the graph is from (top graph post #50) is in the REW .mdat provided (Post #40 this thread) containing the measurements used for MSO, i.e. each sub at each listening position.
This sub is labeled P-Sub2.

 

[BigDan79]

The data the graph is from (top graph post #50) is in the REW .mdat provided (Post #40 this thread) containing the measurements used for MSO, i.e. each sub at each listening position.
This sub is labeled P-Sub2.

PSub2 is in the back of the room. I think my wife would shoot me if I move the Rythmik there because she would see it from other rooms. She is already complaining about the extra subs plus I undersold the size of the Rythmik before buying it. Probably not a good option if I want to continue the hobby.

 

[JStewart]

Well, you have a new awesome sub, you’re enjoying the sound, you have some new tools to work with in the future AND your relationship is intact. IT’S A WIN!

 

[BigDan79]

Well, you have a new awesome sub, you’re enjoying the sound, you have some new tools to work with in the future AND your relationship is intact. IT’S A WIN!

Correct! I did think of something. All of my measurements were the full range front channel. I haven’t measured it from the sub output. I need to measure everything again from the LFE output to see what it looks like in comparison to the calibration measurements.

 

[JStewart]

Correct! I did think of something. All of my measurements were the full range front channel. I haven’t measured it from the sub output. I need to measure everything again from the LFE output to see what it looks like in comparison to the calibration measurements.

It will measure the same from the LFE channel except 1) The LFE channel should have a 120Hz low pass filter in place. This filter only affects the LFE channel and not re-directed bass from the other speakers using the bass management XO and 2) sending signals from REW to channel 4 (the LFE) will be boosted by the processor and be 10dB louder.

 

[BigDan79]

So I finally got a chance to run some more tests. I ran a baseline and the another measurement after running Audyssey. Seems like the Audyssey is not as linear.

 

[BigDan79]

Also, Audyssey set my sub distance to 30’. I had it at 11’. What effect does the speaker distance have on sound?

 

[JStewart]

Also, Audyssey set my sub distance to 30’. I had it at 11’. What effect does the speaker distance have on sound?

It can make a significant difference in the response when not set right. I can post an example in the morning.
Is the graph in #59 subs only or subs and a speaker(s)?
I’d like to think Audssey would get it close but would need data to know for sure.

If you can take the measurements @jtalden specifies by following the link in this post
https://www.avnirvana.com/threads/minidsp-sub-setup.6128/post-46264
he may be able to analyze them.

 

[JStewart]

3 examples of sub distance settings:

Starting with a reasonably good phase alignment in the XO region.

Then adjusting the delay to less than ideal.

A more extreme example with the sub polarity inverted:

Below is the comparison of the 3 examples.
Even the purple vs the blue in the chart below would be very easily audible where its 5dB different over a large part of the XO range. The purple line should sound roughly half as loud where there is a 5dB difference.

Here's a link to a chart that gives an idea of how much musical information is in that range:

http://www.guitarbuilding.org/wp-content/uploads/2014/06/Instrument-Sound-EQ-Chart.pdf

 

[Jack1949]

@JStewart

Thanks for the REW Alignment Tool lesson! I didn't know about that feature, but I now see how it can be very useful.

Jack

 

[JStewart]

@JStewart

Thanks for the REW Alignment Tool lesson! I didn't know about that feature, but I now see how it can be very useful.

Jack

It's a great addition to REW. Thank you @John Mulcahy !!

And thank you @jtalden for the lessons on how to best use it in this thread: https://www.avnirvana.com/threads/understanding-sub-phase-group-delay-for-placement.5976/ and others!

 

[Jack1949]

I'll have to check out that thread.
Thanks again.

 

[BigDan79]

It can make a significant difference in the response when not set right. I can post an example in the morning.
Is the graph in #59 subs only or subs and a speaker(s)?
I’d like to think Audssey would get it close but would need data to know for sure.

If you can take the measurements @jtalden specifies by following the link in this post
https://www.avnirvana.com/threads/minidsp-sub-setup.6128/post-46264
he may be able to analyze them.

The graph was only the sub output. I still have a ton to learn.

I was also wondering if REW can help you figure out the correct eq settings for your main speakers?

 

[JStewart]

The graph was only the sub output. I still have a ton to learn.

I was also wondering if REW can help you figure out the correct eq settings for your main speakers?

Yes, REW has capabilities to generate PEQ (parametric) filters for a variety of hardware/software, so it will likely depend on what what you have to enter eq filters to and process them with.

 

[BigDan79]

Yes, REW has capabilities to generate PEQ (parametric) filters for a variety of hardware/software, so it will likely depend on what what you have to enter eq filters to and process them with.

Here are the eq filters on my receiver.

 

[JStewart]

Here are the eq filters on my receiver.

If you can adjust those equalizer settings while a signal is playing I think REWs RTA (real time analyzer) using a full range Pink Noise PN signal might be the best approach. REW plays the signal and shows you real time SPL results while you're adjusting the EQ settings.
REW EQ does not have the native ability to advise on what settings to use for your EQ. It's possible it could be made to work but it will take some effort.
I'm close to, but not 100% certain on this advice so posting the question in the REW forum might be worthwhile to see if someone will confirm or have a better method to suggest.

 

[BigDan79]

If you can adjust those equalizer settings while a signal is playing I think REWs RTA (real time analyzer) using a full range Pink Noise PN signal might be the best approach. REW plays the signal and shows you real time SPL results while you're adjusting the EQ settings.
REW EQ does not have the native ability to advise on what settings to use for your EQ. It's possible it could be made to work but it will take some effort.
I'm close to, but not 100% certain on this advice so posting the question in the REW forum might be worthwhile to see if someone will confirm or have a better method to suggest.

Thanks for all of the info. I will post this question in the REW section.

I have been watching movies with the settings we configured and I am happy with the result. I am sure that it could be fine tuned more but I am not sure I would notice it. The bass it better than I have ever had it. I am still amazed by the difference adding the Rythmik made. Thanks again for all of your help!