eq of t30s and ot12s for bass

[tactix]

A measurement of what though? A frequency sweep? Recorded music demonstrating the issue?

Pink Noise

Got ya. Will do. Thanks.

[tactix]

There should be a bunch of presets, eg Mono Subs/stereo mains, stereo subs/stereo mains, 3 way etc etc.
Pick one of these presets that you'll never use, save into that and rename it as eg systemtryout. Yes. Everything you've done to date, well no, it will only save the last iteration of all you've been doing.

Now setup a custom installation (no wizard), with eg mono subs and L+R if that's what you're doing. Create your cross points again.Create your target curve at this stage. Creating a target curve requires you to know what to boost and what to cut based on cab response, which in this case is ok because your cabs response charts are in the SPL section. Print each chart, draw a pencil line roughly half way inbetween the peaks and troughs for the bandpass being used. Anything above the line pull down, anything below the line bring up. That's roughly flat (+/- Seth's gain matching).
Now save this as eg Systemtune in another preset you'll never use.

Recall that preset and check it.
Auto EQ ends up with a GEQ curve after it's altered room response to your target curve.
So hit auto EQ, then tweak by ear based on some of what we've discussed already. Save in another preset you'll never use as eg Venue1

Now go through EQ with your monitors.

BTW muddy could be, as suggested already, imbalance in subs and mains, or too much of around 400Hz. Or a combination of both.

You should be able to get crystal clear audio with your cabs. Work at it until you do.
Once you've got it crystal clear at volume, you can then start messing with it to suit your preferred genre.

Hope that's clearer...

Thank you for the detailed write up Grant. What is the goal here? Flattening the response? Isn't that what auto eqing to a flat curve does (compensate for the response of the cabinets (and the room))? When you say use an SPL chart for the bandpass I'm using what do you mean? There are charts for say the T30 in the SPL section that show comparative responses for different drivers and widths of cabs (none are quite what I have) but not based on any filters I'm applying, either the crossover or the high pass. Can you elaborate a bit more?

[Bruce Weldy]

This conversation has gotten pretty deep into the weeds, but I'd like to ask a basic question. You've mentioned your crossover point, but not really in detail.

So, to be precise....

1. Have you high passed the tops?
2. Have you low passed the subs?
3. Did you separate the frequencies for both of those crossover points?

If you didn't do both 1 and 2, then you could have two speakers putting out the same content - instant mud. There are really two crossover points to address - if you only addressed one, then you've got a problem.

If you did both 1 and 2 properly, then you can consider putting space between the two points. For instance - lowpass the subs at 100hz and highpass the tops at 110hz. This helps to get rid of the buildup at the crossover point.

I'd suggest you reset and start over. Run a song through your rig and just focus on balancing the tops to the subs with the EQ set to flat. Don't worry about EQ yet. Get to a point where you feel like they are playing well together. Then use the RTA with the music curve. There will be some really weird cuts and boosts - smooth those out a little. The listen. And listen. And listen. Use the EQ to get rid of what needs to go away - DON"T add to frequencies in any great amount. It's always better to subtract what you need to get rid of than to boost what you want to hear.

You're getting deep into the science and that's fine - but ultimately, you have to allow the art in and start listening with your ears instead your eyes. The curves are good starting points, but you have to pursue the sound regardless of what the screens tell you.

[Bill Fitzmaurice]

Use your ears, but to reiterate an RTA is essential. It will show you precisely where you have peaks and dips. Trying to tune them out with only your ears can be done, but it's a long process of trial and error.

[Bruce Weldy]

Use your ears, but to reiterate an RTA is essential. It will show you precisely where you have peaks and dips. Trying to tune them out with only your ears can be done, but it's a long process of trial and error.

+1

I agree, but felt like we hadn't made sure that the basics were covered first. Sometimes we assume knowledge that may or may not be there and start trouble-shooting the carb, plugs, and ignition to see why the car won't start before we check the gas tank.

[Grant Bunter]

Thank you for the detailed write up Grant. What is the goal here? Flattening the response? Isn't that what auto eqing to a flat curve does (compensate for the response of the cabinets (and the room))? When you say use an SPL chart for the bandpass I'm using what do you mean? There are charts for say the T30 in the SPL section that show comparative responses for different drivers and widths of cabs (none are quite what I have) but not based on any filters I'm applying, either the crossover or the high pass. Can you elaborate a bit more?

Sure!
Auto EQing a flat EQ will adjust both the PA and the room, but it doesn't know what the response of the either is, it just changes what it measures compared to pink noise.

When I say bandpass, subs are 30Hz to say 100Hz (ie the subs bandpass), so only use that portion of the entire graph. Use the chart that is nearest your cab size.
Filters are done by you. The charts are raw data charts.
Similarly, Otops are from 100Hz up, so ignore the chart below 100Hz.
Doing this gets PA response more like flat, even though the EQ trace on the DBX looks like a wiggly line.

Now when you hit auto EQ, it adjusts EQ based on the rooms response to the PA. So you've eliminated one variable.

More wise words have come from Bruce...

[tactix]

Thank you all again for your help. I managed to get back in the space briefly this past weekend.
Grant, I didn't feel I had time to go through the adjustments relative to speaker response as you outlined. I'll give that a shot at when I've got more time in there.
In the meantime I did play with the crossover configuration, matching the tops and sub in output and reducing their frequency overlap. Essentially I steepened the curves, widened the separation between the filters, and boosted the gain on the tops. Here's the configuration I settled on using in this session:

One thing you'll notice is the increase in gain on the tops. This was done to match top and sub outputs without needing to turn down the subs. If I turn down the subs this causes the limiter to start kicking in per-maturely. Ultimately I probably need to another amp to run all four of my tops but for now this seems like a reasonable solution.

Here is a video of pink noise running through the rig for reference: https://vimeo.com/820741276
I did do some peq work on this post autoeq to try to further flatten the response - it's not perfect but workable I figured. I can add a target curve after the response is flat using the graphic eq as needed - works well enough for now.

These changes do seem to have improved the bass some. I think they were overlapping too much - good call Bruce. That said, I still think there's other stuff going on here. Here is a frequency sweep from 20-200hz that I played through the system: https://riverurbanism.com/audiocheck.ne ... FS_10s.wav. When I play this through the PA, the sound seems to pump rather than being rendered as a smooth gradient as does through headphones. Here's a video of this in action https://vimeo.com/820741154
Any idea what's causing this? A phase mismatch perhaps?

Also, is it normal indoors that I should expect the bass to be present and then almost silent as I walk around the room? I've certainly experienced dead spots before but his seems extreme. If I play say a 90hz or 100hz tone and walk around the room the response seems to shift like every 20 feet or so ( I didn't measure). Thoughts on this as well?

[Seth]

WOW! Now THAT is a reverberant room! Holey smokes!

The response is about as flat as you'll be able to get it. Looks good. Great job

In a room that reflective, yes, dead spots (known as nulls) would be expected. Cab placement can help. How were the subs configured in the room in the sweep video?

I highly suspect that the pulsing is also an artifact caused by the rooms acoustic qualities too.

Bodies in the room will improve your situation.

Not to say it can't be done with acceptable results, but I'd recommend dialing in your desired response curve with the Parametric EQ. With the adjustable Q of a parametric EQ, large adjustments over a wide range of frequencies create smooth response adjustments over the effected frequency range. The same curve over the same frequency range, moving the sliders on a graphic EQ to create the same shape, creates a very jagged curve because each slider has a set Q and the response dips in the frequencies between the individual slider frequencies. Not sure that makes sense the way I wrote it. I'll see if I can find a link for you tomorrow.

If you have less than four T30's the high pass should be set to 35Hz, per the plans.

The videos and screenshot data were helpful I put my question in bold so you wouldn't forget to answer it.

[tactix]

In a room that reflective, yes, dead spots (known as nulls) would be expected. Cab placement can help. How were the subs configured in the room in the sweep video?

I highly suspect that the pulsing is also an artifact caused by the rooms acoustic qualities too.

The measurements were taken with the subs corner loaded and v-plated about a foot from the boundary. Tops were adjacent to the subs and cocked so they were pointing towards the middle of the opposite long wall where the RTA mic was located some 15 feet or so in front of that wall.

I tried two speaker placements that day. This one plus another where subs and tops were in the middle of one of the long wall facing the other long wall. Top response seemed best in the corner config, the sound filling the room (as one would expect) while taming some harshness (reflections?) in the high registers. Lower frequencies in the corner lacked punch but was probably the most even in the room. I didn’t test this as systematically as I did with the middle room placement. When placed along the middle of the wall there were places that kicked but lots that did not. I’m trying to get more speaker cable so I can try splitting the tops and subs to see what happens when the tops are in the corner and the subs are along the long wall.

[tactix]

If you have less than four T30's the high pass should be set to 35Hz, per the plans.

Good catch, I had had it configured for 40hz because i had played around with fewer cabs the previous session and couldn’t remember if it was 30 or 35hz for four.

[Grant Bunter]

If you have less than four T30's the high pass should be set to 35Hz, per the plans.

Good catch, I had had it configured for 40hz because i had played around with fewer cabs the previous session and couldn’t remember if it was 30 or 35hz for four.

Only if they are all grouped together for the 30Hz as well...

[Seth]

Here's a video that demonstrates what I was saying about using the graphic EQ to dial in your desired response curve and the effect it creates. https://www.youtube.com/watch?v=rvZXsyCtAew&t=130s

[Grant Bunter]

Grant, I didn't feel I had time to go through the adjustments relative to speaker response as you outlined.

Well, that just means any charts or measurements for the room show the response of the PA and the room together.
I've said this before, you still don't know what's doing what because you have no constant.
You need the constant to be a tuned PA.

Not trying to be horrible, your highest priority should be to tune the system first, outdoors. Nothing else.
Once that's done, that is your target curve, and a place to start in regards to response indoors in a space.

I'm very pleased for you that you have managed to work some things out however...

[Radian]

That said, I still think there's other stuff going on here.

Incorrect choice of cutoff points and filter slopes for the application.

When I play this through the PA, the sound seems to pump rather than being rendered as a smooth gradient as does through headphones. Here's a video of this in action https://vimeo.com/820741154
Any idea what's causing this? A phase mismatch perhaps?

Combination of factors, but primarily comb filtering from too much destructive interference.

Also, is it normal indoors that I should expect the bass to be present and then almost silent as I walk around the room? I've certainly experienced dead spots before but his seems extreme. If I play say a 90hz or 100hz tone and walk around the room the response seems to shift like every 20 feet or so ( I didn't measure). Thoughts on this as well?

No. See above.

[Seth]

That said, I still think there's other stuff going on here.

Incorrect choice of cutoff points and filter slopes for the application.

I'm sure it was a simple editing slip. That quote isn't mine.

Granted, it's not how I'd setup my crossover personally, I didn't see any red flags in reviewing the crossover settings.

Would you mind expanding on that a little?