REW

cheyneb25

Novice Member
Hey Conrad, thanks for responding here. I tried not to be long-winded but I do have some answers to your Q's:...........


Here's a link for a shared folder that I created on DropBox - It has the REW sweeps that I did tonight, with Audyssey turned off and the minidsp tweaks reset. There are also a couple of other files in there that show what the subs look like after all of the alignment tweaks I did for config. 3 (which is what I've been using the last few months); the only difference between the 2 different config. 3 files was the main volume setting in the AVR when I ran them. I made sure I to turn Audyssey off in the AVR but I'm starting to suspect that the Dynamic EQ setting isn't turning off for some reason even though I do turn it off, because the bass still looks hot. Oh well, it's always something...lol.

 

Conrad.

Moderator
I'll take a look at this in more detail tonight but, first thoughts:

1. I don't know if it's been updated but REW has advanced a lot this year in terms of sub alignment. There's a new alignment tool that makes things much quicker and simpler, which is why I asked for each sub's measurement individually. This will allow you to pick two, align them and save that as an output, then add a third, then a fourth, etc. For the gain hack, it won't do any harm but I don't know it'll do any good either. A higher AVR level can help if you're getting issues with an auto-on/off system as a low AVR signal might not be enough to wake the subs.

What you've done is gain match the subs, which I wouldn't recommend. It's generally better to level match them at the MLP, then align/combine and level match again and so on, until you've got a combined response of 75dB. What I suspect you're doing is starting with one sub at 75dB, then adding another (78dB) then another (81dB) and so on, all the way to 89dB.

2. Ok, all seems fine.

3. This is probably fine, the measurements will tell us. For your six subs I'd be looking for "pairs" or responses. You're right, the VNF subs will probably measure the same, in which case, pair them up. You might be right hat the front two measure the same, but they might not. if they do then it also makes sense to pair them up as you've done. You could just get another 2x4 and daisy chain them. That would give you 7 outputs.

What I'm expecting to do later is to align your front two subs and confirm that they can, in fact, be treated as a single sub. Then align those two with the side sub, then the rear sub. Separately I'll align the two rears.

Then we can look at what EQ to apply to the VNFs and then what EQ to apply to the other four subs to get a nice response.

After that we can look at the integration with the front three mains. We'll do a check at the end to make sure that the VNF subs don't ruin the response.

I would suggesting making use of both outputs from the AVR. One to each minidsp input. In the minidsp we'll route one put to the two VNF subs using a splitter, and the other will go to the rest of the subs. That way you can use the trims in the AVR to adjust the balance between the VNF subs and the rest of them.

If you want to run Audyssey then the best place to do it is after alignment and before EQ, that way you're only EQing on top of what Audyssey has done to adjust to taste. If you do it before Audyssey you might end up with two systems fighting each other and you don't know what part of the response is your EQ and what's Audyssey, which makes it hard to adjust anything.

As a side note, I recently re-did my subs and I managed to get Audyssey turned off altogether, so unless it's doing something great with your mains, that's an option too.
 

Conrad.

Moderator
@cheyneb25 - how are you level matching your subs? There's a huge difference between the front three alone. And that rear sub must be massively dominating the sound.

A couple of questions:
- do the two front subs measure the same?
- do the VNF subs measure the same?

I took your measurements and created a combined file. It's often easier to work with multiple measurements in one file. I've attached the file that I worked with.

This is what I saw when I looked at the individual responses

comparisons.jpg

Quite the range there.

Using just the main three measurements (fronts (which is two subs), center, rear) I played about with the timing and levels and got this:

Combined.jpg

So I reckon with proper level matching and alignment you can definitely improve on what you've got now. You can also adjust the timings on the VNF subs and they don't affect the overall response.

Have a look at the MDAT and you can see what I've done in terms of alignments and gains. Some of the swings are pretty large, you might be able to get away with less.
 

Attachments

  • All Subs.txt
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cheyneb25

Novice Member
@cheyneb25 - how are you level matching your subs? There's a huge difference between the front three alone. And that rear sub must be massively dominating the sound.

A couple of questions:
- do the two front subs measure the same?
- do the VNF subs measure the same?

I took your measurements and created a combined file. It's often easier to work with multiple measurements in one file. I've attached the file that I worked with.

This is what I saw when I looked at the individual responses

View attachment 1404909

Quite the range there.

Using just the main three measurements (fronts (which is two subs), center, rear) I played about with the timing and levels and got this:

View attachment 1404911

So I reckon with proper level matching and alignment you can definitely improve on what you've got now. You can also adjust the timings on the VNF subs and they don't affect the overall response.

Have a look at the MDAT and you can see what I've done in terms of alignments and gains. Some of the swings are pretty large, you might be able to get away with less.


Hey Conrad, thanks for taking the time to look at those REW files and tweak around with them. Per your request, I attempted to measure all 6 subs individually; for the 2 sub pairs I just alternated turning one of the 2 subs off when I was measuring them by themselves, I hope that will work ok. . The individual responses for the front corner subs were so similar that I thought I might be doing it wrong or missing something, but it stayed the same even after re-measuring 2 more times. That said, I still have doubts that I didn't miss something..

Clearly, there are plenty of gaps in my knowledge so I'm researching more on how to properly do level matching since gain matching isn't something you recommend with the 2 vnf subs in the chain.

You're definitely right that the rear wall sub appears to be the main player in my sub response, It sounds louder than the others do when I'm listening to it during the REW sweeps, I had assumed it was because of boundary gain.

I'm not sure of the exact reason the front 3 subs vary so much but I can try to give you some context. On the other side of the wall where the front left sub is located is the foundation of my house and it is underground, but the wall next to the front right sub just separates the theater area from the laundry room, so it is just standard drywall on studs w/ no insulation in it. The center sub is within 5 inches of the wall (which is also completely underground on the other side of it) and is elevated roughly midway up the wall, roughly 3'10" off of the floor.

There have been many different iterations of where the subs were placed in the room over the last few years and it seems like I have found a workable solution in where they are right now. By placing the subs in such widely varying positions in the room, my goal was to mediate room modes as much as possible.


- I had been procrastinating doing it but I did finally get around to updating REW with the new beta version.
- I saw some areas that mentioned the 'timing reference' you were talking about when I was looking through REW last night; were you referring to 'use loopback as timing reference' or the 'acoustic timing reference' (those were the 2 options I saw in the dropdown for it)?
- I did see the sub alignment tool in there as well but I haven't tried to mess around with it yet.

I made a new Dropbox folder with my latest .mdat files - there are individual measurements for each of the 6 subs in there and I also did measurements for the 2 sub pairs for comparison. I also included a file with the 3 different configurations that I created in the minidsp. Config. 3 is what I've been using up to this point, but I did 2 new configurations last night and I went ahead and switched to Config. 2 when i was watching a movie that I know pretty well to see if I liked it better (I did, lol).


 

Conrad.

Moderator
I share your suspicion of the front measurements. The issue for me is that the combined response is exactly the same as each of the individual responses. If the subs were perfectly in phase you'd get a 3dB rise. If they're out of phase then you'd get a different combined response.

As far as I'm aware there's no way to get exactly the same response with subs 1, 2, and 1+2. Not unless you dropped the levels between measuring the subs individually and measuring them together. Are you changing the levels between measurements?

If you use the alignment tool in REW you get a very different level for the front two.

I suggest we start there. If we don't have confidence in the measurements then there's not much point working up from there, we won't get the results the we expect.

First thing, timing references.

An acoustic timing reference is a short signal played at the beginning of a measurement that allows REW to know how far ahead or behind the measured speaker is relative to the reference. If you use the same reference for two subs you can calculate the relative position of the subs against each other. This allows us to compare two individual measurements and see how the phases will interact at the measured position.

Choose Acoustic timing reference from the Timing dropdown on the measure window. That'll enable a second box at the bottom, Ref Output. In that dropdown choose a base layer speaker, but choose a different speaker than the channel you'll use to measure the subs on. For now use LFE in the output and any speaker as ref. I like to use a surround channel but it doesn't matter.

1605812664585.png

Now take the measurements of your front corner subs, both with the same timing reference. Measuring one with the other off is a fine way to do it. It's probably worth checking the inputs and outputs in the minidsp plug-in to make sure that they signal is going where you expect, and walking over to the sub while it's measuring to make sure that the sub you think is playing is actually playing. Sounds obvious but sometimes it's hard to tell (which is why subs don't need to be near speakers).

Take a measurement of them combined as well.

When you're confident that you have both subs measured correctly, go to All SPL, Controls, and choose the alignment tool. Select one sub in the top dropdown and the other in the bottom dropdown and it'll show you the combined response. The predicted measurement (the black line) should match up with the combined response. Currently it doesn't, it's 6dB too low.

This is what we should get:

1605812983984.png

One of the three measurements I have selected should match that black line, but it doesn't. Instead it's exactly the same as the other two.

Have a look at that and see how you get on.

Also, as a tip, it's much more useful to name the measurements sensibly than to use the comments. You can see in this file I've renamed the measurements to Front Right (FR), Front Left (FL), Fronts, etc.

It makes it much more usable in the checkboxes at the bottom and the dropdowns in the time alignment tool. You can still use the comments box, but it's more for a record of what changes have been applied to the measurements.
 

cheyneb25

Novice Member
Conrad,

I appreciate your input on my situation, your comments thus far have been invaluable to me and you've given me plenty to chew on. I'm still learning about how to do all of this stuff properly on the fly, so apologies for any silly Q's or delays in my correspondence.

I'll double check everything in the equipment chain and try to wrap my head around the inconsistency with the front corner sub measurements. It can be a little frustrating for me when I do the measuring because I'll do something one way and it doesn't work (i.e., like the front subs not measuring the way they should) but then when I try doing the exact same again later and do the exact same process without changing anything, suddenly it does work or ill get a different result... My lack of a full understanding of REW, combined with the fact that my minidsp doesn't like staying connected/synced to my PC, causes me all sorts of grief, because then the simple things are no longer simple.

And to your inquiry about changing the volume levels between the measurements, no I did not. I always have the main volume in my Marantz AVR set to -10dB when I do my measurements. I chose that setting l because I understood it to be the 'reference' volume level.

I will try to do as much with this as I can tonight and tomorrow but the weekend is when I will have the most time to try and implement your suggestions and do some more thorough re-measuring. I'll also try to make the naming of my measurements and files a little more coherent, lol.
 

Conrad.

Moderator
No problem at all. Take your time. Once it “clicks” things will be a lot easier. I find it helps to just thing through the signal chain when you’re pressing measure. Which speakers will play and which won’t; is everything connected and powered to support that.

You might find out useful to use the tone generator and send signals to the individual subs, just to see if you can make it happen.

How are you connecting to the minidsp? If it’s via wireless I’d suggest investing in a long USB cable, at least for testing.

I’m around all weekend (lockdown) so will have time to answer and look at any measurements.
 

cheyneb25

Novice Member
There is definitely a lot to think through and boxes to check off when doing the measuring. I would be surprised if the cumulative amount of time that I have spent with REW exceeded 13 hrs at this point, lol.

I'll map out how everything is connected in my system and create a basic diagram so that I can organize my own thoughts better, and also to give some you a lil more detail on how it's all set up.

I'll also play around with the tone generator tonight and see what happens.

I do have my minidsp hooked up to the PC w/ a USB cable; the issue I have w/ it disconnecting apparently isn't all that uncommon based on what I had read up on when I first set it all up in my chain.
 

cheyneb25

Novice Member
Conrad,

Ok, so in 2020 I've learned 2 things - 1. common sense is no longer common; and 2. I should probably insult my gear more often, because doing so seems to motivate it into working properly, lol.

I did some more measurements, and without changing my process at all it seems to have worked out much better this time around. My minidsp stayed connected the entire time and I was also able to successfully get individual sub measurements for each of the 2 subs in both sub pairs. And as expected, although they were fairly similar, they definitely measured differently from each other.

One caveat that I must sheepishly admit to though... I did indeed have my outputs mixed up for which output went to which subs. A couple of months ago I had redesigned and rebuilt the center portion of the entertainment center cabinetry that holds my TV, AVR, and other source components, and in doing so I had unhooked all of the gear so that I could swap in the new section. I must have reconnected the subs back to the minidsp incorrectly (I should have color coded them) because I discovered that I had reversed where some of the outputs should have been plugged in. I made sure to verify it this time with the ol' 'hand on the sub when the sweep is running' trick, lol. So, even though we all occasionally fall victim to overthinking things when we troubleshoot our issues and not doing the simple things 1st (like double checking all connections) I am relieved that I was able to narrow down at least some of the trouble I was having.

I cleaned up my Dropbox files and removed everything but the new REW sweeps I ran last night. I included below a new link for the updated .mdat files; it includes each of the front corner subs alone and also measured together, and the same for the vnf subs. There is also a file with the 3 minidsp configurations I've created so far in my attempts to align the subs, I like how config. 2 looks the best. I know that the 3 configurations I've created thus far likely aren't that relevant, I just wanted to get some more practice on the process itself.


I will re-measure the other subs in the chain again tonight and create another REW file with the raw responses for all 4 of the minidsp's outputs.

One last thing here, if you wouldn't care to elaborate on a couple of things:
1. After reading some application notes in a couple of threads on minidsp's web site, I believe I have a better grasp of the level matching concept itself, but I don't think I asked you yet how it is that you level match your subs.
2. If I were to get another minidsp 2x4 HD to expand the # of potential sub outputs available to me, how would I go about daisy chaining them? The concept seemed challenging to me since I think I would have to connect to each minidsp unit separately with my PC when doing the alignment process. Could I just run the far field subs off of one minidsp hooked up to sub output 1 on the AVR, and the vnf subs on a 2nd minidsp hooked up to the AVR's sub output 2? Or would that not work because you couldn't align them all together?

Looking forward to your thoughts sir, happy Friday to you!
 

Conrad.

Moderator
I wouldn't worry about muddling up cabling, it happens to the best of us.
I (relatively recently) ran hooked up my second sub output to my minidsp and routed both inputs to all subs without thinking about the fact that output 1 and output 2 from the processor had different EQ. My system sounded dreadful for about three weeks and I couldn't work out why. When I finally gave up and measured it I saw that output 1 and 2 were basically cancelling each other out!

Looking at your results, the front subs are much more in line with what I'd expect to see, good job. Now we can see quite clearly the disadvantage of gain matching as opposed to level matching. Both front subs are gain matched, but the FL sub is 5.5dB quieter than FR. If you level match them at the MLP using the REW SPL meter (we'll come back to this in a second) you should end up with measurements that pretty much match from 25-50Hz. After that you get differences but that's because of the differences in symmetry of your space and it's construction.

To level match I do the following:
  • Set the mic in the listening position, turn on the SPL meter, set it to Z weighting, slow (S).
  • Play a tone from one sub, make a note of the level. It'll bounce around a bit but you should get a sense of the central value. You can use the min/max values and split the difference. Just make sure you're out of the way and hit reset a few times. Eventually the min/max numbers will settle. You only need to be accurate to about 1 or 2dB so don't stress over this.
  • Then play a tone from the other sub. Adjust the gain and use the SPL meter and min/max values to get to the same level at the MLP.
Now if you re-measure you should end up with something that looks like the attached (I added 5.5dB to the FR sub, created an aligned sum and then EQd it)


That response alone looks pretty good with very few filters.

The good thing is though that you're right, the front subs can share an output on the minidsp. the response without any delay adjustment is good enough to be EQd as a single sub, once they're level matched. I'm pretty confident we'll find the same with the rear VNF subs.

Next, I'd level match all the subs and measure them all with no EQ on the LFE channel.
So I'd expect:
Front corner subs (one measurement, once level matched they're good).
Front center sub
Rear sub
VNF sub 1
VNF sub 2

All with a consistent timing reference. If we can get that file we can time align the main four subs. Separately we'll confirm that the VNF ones can be a single sub and, when EQd, don't interfere with the main subs.
 

cheyneb25

Novice Member
So, after doing some more work on the setup last night and today I've been able to climb a little higher up the mountain of perfection. Although, to be fair, I don't know of anyone ever having reached the summit, lol.

Using your directions, I level matched all of the subs for all 4 of the configurations I've created in the minidsp, then I tweaked the overall sub output level in my AVR so it met my personal preference on how bass heavy it was. The various combinations of delay and inversion for the 4 configurations have yielded a good variety of responses but they do all have some commonality in some areas; the configuration that I like the best remains Config. 2.

The response that you got with your tweaks is pretty similar to the one I did for Config. 2 between 27Hz and 70Hz; I haven't even used any EQ filters yet, I've only aligned them in the minidsp so far, so I'm pretty stoked about that. I think the only reason that I'm getting additional output from 70Hz to around 104Hz is just because my VNF subs are also in the mix with my alignment attempt, whereas I believe you did not factor those subs into yours.

I am, however, getting a pretty uneven response between 104Hz to 120Hz - will that still be a big deal since I'm crossing over my subs over to my mains @ 80Hz? I know that crossovers aren't a hard cutoff point and they actually just roll off. I could probably tweak around some more in the minidsp and figure out why it's out there dropping there and try to fix it, but if it's not a big deal then that would be fantastic.

I was pretty happy that between 20Hz and 103Hz my FR only varied by about 5.5 dBs from the lowest dip to the highest peak, that's easily the best that I have been able to accomplish so far

Here is the newest Dropbox link with all 4 Configurations loaded in my minidsp and all of them are level matched at the MLP. I will admit that I forgot to do timing references for the configurations when I was measuring in REW but I'll try to make sure that I do that when I work on this some more tomorrow.

I hope you are having a good weekend so far, cheers!

 

Conrad.

Moderator
Remember that the response I showed you was un-eq'd and the front subs only. I haven't factored in the side sub, the rear sub, or the VNF subs.

I reckon we can get a really nice response across the four main subs (excluding the VNF subs) without much EQ, if any.

We'll align the VNF subs separately and EQ them to give a flat response and then time align that pair with the other four, just so that they don't interfere with the response too much.

At the end of all this you'll have two virtual subs: sub one will be the four main subs, sub two will be the pair of VNF subs.

Those configs look good. I agree that 2 looks good across the board, 4 option 1 looks fun with that bump in the chest slam area but it needs turning up so that the body of the response is aligned with response 2 but the 60Hz peak rises up above it - I reckon you'll enjoy that one. 1 and 3 I would ditch.

Over the crossover is important as the LFE channel uses that range. However once you start going higher it becomes less important as there's less and less content the higher you go.

For now, a file showing each sub's response, level matched and with a timing reference would be great. You can combine the two front corner subs as one, we know they work ok with no alignment.

Get in the habit of always using a timing reference. It's no extra work and to paraphrase Clarence Worly in True Romance: it's better to have a timing reference and not need it than to need a timing reference and not have it.
 

Wull

Well-known Member
@Conrad. When time aligning main channels with the sub channel, do you keep the left and right channels separate, or do you combine these together, as per your idiots guide point 1?

So - idiots guide:-

0. I click on settings top right.
1. I calculate the average of the L&R with ‘trace arithmetic’ using (A + B /2) and save that “average’ trace
2. I click on ‘Alignment Tool’
3. I compare the ‘average‘ trace (top slot) with the sub (sub at bottom slot)
4. I place cursor on Xover used
5. I click ‘align phase at cursor’
6. If that gives me a positive delay on the sub on bottom trace I need to increase the ms delay on the sub or decrease the ms delay on all of the mains. Conversely, if I get a negative delay showing for sub I decrease ms delay of sub or increase ms delay for all the mains by that amount.
7. The three lines on the phase graph should now cross at the cursor (xover) line but that cross won't likely be at 0 or 180 angle, it could be anywhere, at any angle?
8. I click ‘aligned sum’ to get the summed result - that creates the ‘aligned‘ trace.
 

Conrad.

Moderator
Is that mine? I don't think I've ever used the trace arithmetic function.

Either way, I don't tend to use L+R, I measure everything separately, at least as the primary measurement. I time align the mains. There are use cases where measuring both together is useful, like if you have a particularly low crossover.

My understanding is that a response becomes mono and non-localisable below about 60Hz which is why you can get away with a single sub and it doesn't need to be near the mains. If you're using a very low crossover you need to consider the interaction of the mains with each other as cont

My feeling is that if you're crossing over at a standard frequency then time aligning the mains and time aligning each main with the subs will be enough.

I'm usually interested in two things:

- the integration of each main and the sub(s) to handle the redirected bass that make up a pair of full range speakers. In this case time aligning the mains should be enough so that they constructively sum if they both play the same frequency. Obviously anything below the crossover will be played by the sub(s) and will therefore alway be time aligned with itself, if that makes sense.

- the integration of the LFE channel with the mains, although this is secondary. In this case the LFE below the crossover will be time aligned with the bass below the crossover (it's the same subs playing both), through the crossover will be time aligned because that's done as part of the sub integration. Above the crossover is worth inspecting but LFE content above 80Hz is pretty light so I only really give it a cursory glance.

It might be worth checking that, due to the room, you're not getting cancellations between the mains, but I'm not sure what you'd do about it other than adjust placement. I don't have any placement options so I don't bother.
 

cheyneb25

Novice Member
Hey Conrad.

I ran those REW sweeps you requested. I did a measurement for each of the 6 subs by themselves, and also 2 additional measurements for each of the 2 sub pairs. They all have the acoustic timing reference, but when I was setting up the sweep parameters in the dropdown box you mentioned I only had options for L and R channels (no C or surrounds, so I'm assuming I need to change a setting or something in REW), so I used the main R speaker as the timing reference source in the base layer.

In the Dropbox file I shared (link below) I also included a measurement from 20-18,000 Hz with 1/24th smoothing applied to make it more readable. I was just wondering if anything in the higher frequencies jumped out at you as an issue, specifically in the 500-8,000 Hz range.

I did have a dumb moment though when I was adjusting the sweep's volume in REW... It's usually set at the default -30dBFS in REW and my AVR set to -10dB. I must have had a brain block because when I decided to change it in REW to -20dBFS I typed it incorrectly and it reverted to 0dBFS instead and for the life of me I couldn't get it to change (until I figured out how dumb I was being after the fact). So while I was having that fail I just decided change the AVR volume down to -30dB instead. So I said all that just to say that the overall volume for that 20-18,000 Hz sweep was a little bit different compared to the sweeps that I ran for the subs.

In your previous post you had said, "At the end of all this you'll have two virtual subs: sub one will be the four main subs, sub two will be the pair of VNF subs." I may be getting ahead of myself in this process, but if you could elaborate a little on doing the VNF subs separately... How would I go about doing that in the minidsp and REW? Or would I be utilizing the 2 sub outs on the AVR, each going in to a separate minidsp? I was just a lil fuzzy on the specifics of it.

 

Wull

Well-known Member
Is that mine? I don't think I've ever used the trace arithmetic function.

Sorry Conrad, I think that may have been Lexicon’s way of working. I tend to snip potential information without making a note of whom posted it.

Thanks for your detailed reply, I may come back to you once I’m up and running again.
 

Conrad.

Moderator
Hey Conrad.

I ran those REW sweeps you requested. I did a measurement for each of the 6 subs by themselves, and also 2 additional measurements for each of the 2 sub pairs. They all have the acoustic timing reference, but when I was setting up the sweep parameters in the dropdown box you mentioned I only had options for L and R channels (no C or surrounds, so I'm assuming I need to change a setting or something in REW), so I used the main R speaker as the timing reference source in the base layer.

In the Dropbox file I shared (link below) I also included a measurement from 20-18,000 Hz with 1/24th smoothing applied to make it more readable. I was just wondering if anything in the higher frequencies jumped out at you as an issue, specifically in the 500-8,000 Hz range.

I did have a dumb moment though when I was adjusting the sweep's volume in REW... It's usually set at the default -30dBFS in REW and my AVR set to -10dB. I must have had a brain block because when I decided to change it in REW to -20dBFS I typed it incorrectly and it reverted to 0dBFS instead and for the life of me I couldn't get it to change (until I figured out how dumb I was being after the fact). So while I was having that fail I just decided change the AVR volume down to -30dB instead. So I said all that just to say that the overall volume for that 20-18,000 Hz sweep was a little bit different compared to the sweeps that I ran for the subs.

In your previous post you had said, "At the end of all this you'll have two virtual subs: sub one will be the four main subs, sub two will be the pair of VNF subs." I may be getting ahead of myself in this process, but if you could elaborate a little on doing the VNF subs separately... How would I go about doing that in the minidsp and REW? Or would I be utilizing the 2 sub outs on the AVR, each going in to a separate minidsp? I was just a lil fuzzy on the specifics of it.


Thanks for this, very useful. I've attached my version here. You can get a nice response with no EQ, just using time alignment.

This is just using time alignment, all using one minidsp:

combined.jpg

Here's what I did (are you ready!?)

  • FL and FR subs, as we know, integrate well so I just used the combined response you already measured.
  • I tried the FL and FR with the center but I couldn't get it to work.
  • Instead I added the rear sub with a 1.5ms delay on the rear. This actually gives a really nice response. I could have stopped there but as you have six subs let's integrate six subs :)
  • Adding in the center gives you a sharp null at about 106Hz but that likely won't be audible. As there's no timing change you can play about with having that sub or not, just watch the levels. More on that later.

With that combined four sub response I EQd it, exported the EQ'd response and re-imported it so that we now have a measurement called (F + R) + C-EQ -- (Fronts, Rear, Center, with EQ)

  • For VNF we know we want to handle things differently. Your VNF response is pretty poor, it's rolls off hard at 40Hz. Those subs really aren't adding anything but it's fine, we can EQ them flat and you'll get all that chest slam from 40-100Hz in the back.
  • The combined response of the two VNF subs can't be improved with timing, so I just EQd it quite hard and got a nice rising response. I exported and re-imported the EQd VNF subs as a new measurement.

Combining those responses (four subs, plus the two VNF) with a bit of timing gives this:

all.jpg

Orange is the four main subs, blu is the VNF subs, green is all combined.
So the VNF and the main subs have different EQ and different responses but they don't interfere with each other.

In your previous post you had said, "At the end of all this you'll have two virtual subs: sub one will be the four main subs, sub two will be the pair of VNF subs." I may be getting ahead of myself in this process, but if you could elaborate a little on doing the VNF subs separately... How would I go about doing that in the minidsp and REW? Or would I be utilizing the 2 sub outs on the AVR, each going in to a separate minidsp? I was just a lil fuzzy on the specifics of it.

Here's the chain:

AVR output 1 - minidsp input 1 - minidsp output 1 - Y splitter - front left and front right subs
AVR output 1 - minidsp input 1 - minidsp output 2 - rear sub (1.5ms delay)
AVR output 1 - minidsp input 1 - minidsp output 3 - center sub
AVR output 2 - minidsp input 1 - minidsp output 4 - Y splitter - VNF Subs (7ms delay)

So the front L and R subs are a "virtual" sub on one minidsp output and the VNF subs are also a "virtual" sub that take up one minidsp output. I think this is what you already had to be honest.

It also gives you independent trims in the AVR for the farfield subs vs the VNF subs. Changing the level of the VNF subs doesn't have much of an effect on the overall response so play about until you're happy.

I've attached the EQ for outputs 1, 2, 3 (FF Subs) and output 4 (VNF subs)

It's worth going step by step to ensure that what you get at each stage matches the predictions in REW.

As for levels, if you turn that center sub off the same EQ should still be good but the 106Hz null will disappear. The level will drop by a dB or two though, so you might need to trim adjust.

I'll be interested to see if, once this is applied, you still need to run the same levels. You're running your subs 15dB hot which is absolutely nuts. I'm wondering if it's not SPL you're craving but ULF. Your response is rolling off at 30Hz which is pretty high.

After all that, as a complete curveball, you might be better off selling the six and getting a pair of ported 18" monsters from the likes of JTR, HSU or PSA. If you put them in the right place they'll blow you away! Smaller driver subs are only ever going to be able to play so low, so loud. More drivers doesn't give you a lower response. It'll give you more output with less distortion and a smoother response with minimal EQ, but if you want a response that hits the teens you need bigger drivers.

Being in the US I'm guessing you're on concrete, which means to get the room wobbling you need ported. You have lots of options. Just a thought.

Here's the MDAT I worked in: Integration - Conrad.mdat

I had a look at your full range response too, nothing in there to worry about except maybe that spike at 200Hz. Other than that I wouldn't EQ. Is that post Audyssey?
 

Attachments

  • FF Subs.txt
    627 bytes · Views: 10
  • VNF Subs.txt
    935 bytes · Views: 8

Frozzy

Active Member
Evening all, I've recently purchased a UMIK-1 to try and make any improvements I can. I've made a few measurements in the 2 seats which are usually used, with the results below:
5.1 Measure

I haven't got a MiniDSP 2x4, so for the Sub (1723 1V) I assume the built in parametric EQ can be used?
 

Conrad.

Moderator
Absolutely. There's no requirement for a minidsp. I've used JRiver, processor PEQ, and Sub EQ, all with similar effects. The recommendations for a minidsp are usually that they're pretty cheap, easy to get hold of, comprehensive in terms of their capability, and good at what they do. To replicate their functionality in a processor you're looking at $$$.

You can customise the filter generation within REW so that it only uses as many as you have in your PEQ, and you can limit the boosts to line up with the onboard controls too.

Using onboard sub EQ is actually a really good idea as the manufacturers know the amp/driver/cabinet combo and capability. They won't build PEQ in that allows you to do things that could damage the sub. You could easily do damage with a minidsp.

I used onboard EQ with my velodyne and it worked well. I'm interested to see how you get on.
 

Frozzy

Active Member
Thanks for the reply - I'll spend a couple weeks gathering information and by then I hope Arendal release the app to make the EQ changes that much easier, then give it a go.
 

maxkolonko123

Active Member
@Conrad.

Hey buddy,

How would you match subwoofer levels with different capability ? lets say we got 1 sub is bottoming out at -10MV but 2nd sub can go to 0 MV without any distortion or even further, what we should do in such situation ?
 

Conrad.

Moderator
Oh dear, what have you done? :D

It's a tough one and I'd really need to see the responses to be able to comment meaningfully.
At a guess though you've got a few options:
- find out where the lesser sub is bottoming out and put a high pass filter on if so that it doesn't play that low (assuming that it's the low end it's struggling with)
- use the lesser sub as a VNF sub
- turn the gain down on the lesser sub so that it bottoms out when the system's at 0dB, but it's at a lower relative volume, and hope that it contributes meaningfully to the response.

An example for point three:

Say that, at -20MV sub one is at 80dB and sub two (the lesser sub) is at 80dB.
You turn MV up to -10 and both are at 90dB but sub two is starting to struggle
You turn MV up to 0 and sub one is at 100dB and sub two is making some horrible noises.

What you could do is turn sub two's gain down so that at -20MV sub one is at 80dB and sub two is at 70dB.
Now when you go to -10MV sub one is at 90dB again and sub two is only at 80dB so it's fine.
Then at 0MV sub one is at 100dB and sub two is at 90dB and is starting to struggle.

This is only any use if a sub playing 10dB quieter is any use. The better sub is going to be doing the lions share of the work. Unless you know that a lesser sub will give you some very specific improvement this is a bad plan.
 

maxkolonko123

Active Member
Oh dear, what have you done? :D

It's a tough one and I'd really need to see the responses to be able to comment meaningfully.
At a guess though you've got a few options:
- find out where the lesser sub is bottoming out and put a high pass filter on if so that it doesn't play that low (assuming that it's the low end it's struggling with)
- use the lesser sub as a VNF sub
- turn the gain down on the lesser sub so that it bottoms out when the system's at 0dB, but it's at a lower relative volume, and hope that it contributes meaningfully to the response.

An example for point three:

Say that, at -20MV sub one is at 80dB and sub two (the lesser sub) is at 80dB.
You turn MV up to -10 and both are at 90dB but sub two is starting to struggle
You turn MV up to 0 and sub one is at 100dB and sub two is making some horrible noises.

What you could do is turn sub two's gain down so that at -20MV sub one is at 80dB and sub two is at 70dB.
Now when you go to -10MV sub one is at 90dB again and sub two is only at 80dB so it's fine.
Then at 0MV sub one is at 100dB and sub two is at 90dB and is starting to struggle.

This is only any use if a sub playing 10dB quieter is any use. The better sub is going to be doing the lions share of the work. Unless you know that a lesser sub will give you some very specific improvement this is a bad plan.

I'm quite close to ordering RS2 :D so this question was more out of curiosity, cause i doubt in my situation 3010 can match something like jtr, but we not there yet Conrad, you'll be first to know once i place the order :smashin:
 

Conrad.

Moderator
Ok then. So "lesser sub" takes on a different meaning when the lesser sub is a dual 15"!
 

cheyneb25

Novice Member
- For VNF we know we want to handle things differently. Your VNF response is pretty poor, it's rolls off hard at 40Hz. Those subs really aren't adding anything but it's fine, we can EQ them flat and you'll get all that chest slam from 40-100Hz in the back.
The combined response of the two VNF subs can't be improved with timing, so I just EQd it quite hard and got a nice rising response. I exported and re-imported the EQd VNF subs as a new measurement.

- AVR output 2 - minidsp input 1 - minidsp output 4 - Y splitter - VNF Subs (7ms delay)

- So the front L and R subs are a "virtual" sub on one minidsp output and the VNF subs are also a "virtual" sub that take up one minidsp output. I think this is what you already had to be honest.

- It also gives you independent trims in the AVR for the farfield subs vs the VNF subs. Changing the level of the VNF subs doesn't have much of an effect on the overall response so play about until you're happy.

- As for levels, if you turn that center sub off the same EQ should still be good but the 106Hz null will disappear. The level will drop by a dB or two though, so you might need to trim adjust.

- I'll be interested to see if, once this is applied, you still need to run the same levels. You're running your subs 15dB hot which is absolutely nuts. I'm wondering if it's not SPL you're craving but ULF. Your response is rolling off at 30Hz which is pretty high.

- After all that, as a complete curveball, you might be better off selling the six and getting a pair of ported 18" monsters from the likes of JTR, HSU or PSA. If you put them in the right place they'll blow you away! Smaller driver subs are only ever going to be able to play so low, so loud. More drivers doesn't give you a lower response. It'll give you more output with less distortion and a smoother response with minimal EQ, but if you want a response that hits the teens you need bigger drivers.

- I had a look at your full range response too, nothing in there to worry about except maybe that spike at 200Hz. Other than that I wouldn't EQ. Is that post Audyssey?


Hey Conrad, apologies for the delay in my response to your last post (which was quite excellent btw). I have not yet implemented all of your suggestions from the last post, but to be fair, if I don't fully understand every detail then I tend to take my time with stuff so I don't screw it up. That means that usually I end up being the turtle and not the hare, lol. And I am glad to hear that the full frequency response looks good; I had done some acoustic treatment in the room and was curious on if I had overdone it or anything along those lines. Here are my replies to the parts of your post that I quoted above.

1. - I knew that the VNF subs would be tricky and might not measure as well as the others would, but I had hoped that with those subs it would help to smooth out the overall response and maybe gain some additional output as well. My primary goal though was to provide some really good slam and give a good TR at the seating positions since I had decided against doing butt kickers.

2. - In the connection chain that you listed, you had the AVR's sub output 2 going to input 1 in the minidsp, so I wanted to clarify - I would need to use a Y-splitter (2 female to 1 male) to combine the 2 sub outs on the AVR to have them both going into input 1 on the minidsp, correct?

3. - You are right sir, that is indeed how I was splitting the signal for the 2 sub pairs coming out from the minidsp.

4. - If I am to use a splitter for the 2 sub outputs on the AVR going to input 1 on the minidsp, would that mess with the signal being sent to the minidsp at all? And when you say the trims, I'm assuming that you mean the individual channel trims - I have 3 different ways of adjusting the the levels for the subs in my AVR (levels, trims, and sub adjustment) so I just wanted to be sure.

5. - I do like the small bump in overall output that the front center sub gives me, but to your point, I could simply adjust the sub levels to compensate so I am considering taking it out of the sub chain to flatten my response.

6. - To be honest, I'm not really sure why the subs run that hot. I try to ensure that the Dynamic EQ function is turned off in the AVR when I run my sweeps, and I did level match everything to around 75dB in the minidsp per your advice. For what its worth though, when I watch TV or movies or listen to music the bass doesn't sound too overwhelming or too intense (except on some content that was mixed to be intentionally bass heavy), but I guess that could just be my personal perception/preference.
And as far as craving the ULF bass, I'm not sure if that's what I really want or not since I'm not sure that I've ever had any real exposure to ULF capable subs in a system. So far, I am really happy with the smoothness of the bass response after all the work I had done, and it has been much more refined with your excellent contributions. I just like having a strong 'kick' or 'pop' on the bass effects in a movie when it's called for.

7. - I will take your tip on potentially changing out the 6 subs for 2 or 3 really good ones under consideration. It was a battle to get wife approval on having that many subs in the room so I don't want to revert to a smaller # of subs too quickly, lest I put myself at a disadvantage for future negotiations, lol. What led me to take the approach that I did was a combination of 2 things - budget (I got those 6 subs for under $780 in total) and a desire to get the smoothest response that I could get. So far, I feel pretty happy with how the bass is performing in the system, but who knows how I may feel down the road if I get bitten by the 'optimization bug' again, lol.

I hope you had an excellent thanksgiving holiday; that is if you celebrate it where you are located. I think I remember your post saying 'with you being in the US'. I'll be looking forward to hearing your advice again when I start trying to properly integrate my mains with the subs. Until next time, take care sir!
 

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