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Author Topic: DIY monitors Smaart  (Read 10036 times)

Montez Carter

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DIY monitors Smaart
« on: January 25, 2012, 03:26:41 am »

I have some 15" X 1.4" DIY monitors that I have made and I have downloaded the Smaart demo program. I tuned them by ear and then placed them outside on my dock away from the building. I ran some pink noize through them and measured with my DBX measurement mic  and basically adjusted the levels and applied some EQ to get them fairly flat on the smart RTA screen. They are biamped by Crown XTI 2000's with inserts from DBX 1231's. I then ran some source material through them and swept them with a Shure PGX/Sm-58 capsule wireless system check 1-2 etc. and everything was fine I had decent enough gain before feedback. I did notice my problem freq is 800-1000hz and 2.2-2.5k I damn near have this all the way notched on the DBX to get the amount of GBF that i felt was acceptable. Thanksgiving weekend sound checking and they started whaling something terrible in this same problem range. I notched it out and the graph was butchered by the time I got done. National rappers so most of the music was in sidefills with vocals predominantly in the monitors anyway so they were happy but I was not comfortable. My question is if i move the crossover point from 1.2K where it is now will that help out this problem or is this a phase problem and I am just trying to fix it with EQ. I have the tools but don't know how to use them to fix my problem. So any help would be greatly appreciated.
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Timo Beckman

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Re: DIY monitors Smaart
« Reply #1 on: January 25, 2012, 04:33:13 am »

Could you post screenshots from smaart in fft mode? So the solo response of the high and low driver with phase included

What kind of high and lowpass settings do you use on the monitor
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John Halliburton

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Re: DIY monitors Smaart
« Reply #2 on: January 25, 2012, 08:57:18 am »

I have some 15" X 1.4" DIY monitors that I have made and I have downloaded the Smaart demo program. I tuned them by ear and then placed them outside on my dock away from the building. I ran some pink noize through them and measured with my DBX measurement mic  and basically adjusted the levels and applied some EQ to get them fairly flat on the smart RTA screen. They are biamped by Crown XTI 2000's with inserts from DBX 1231's. I then ran some source material through them and swept them with a Shure PGX/Sm-58 capsule wireless system check 1-2 etc. and everything was fine I had decent enough gain before feedback. I did notice my problem freq is 800-1000hz and 2.2-2.5k I damn near have this all the way notched on the DBX to get the amount of GBF that i felt was acceptable. Thanksgiving weekend sound checking and they started whaling something terrible in this same problem range. I notched it out and the graph was butchered by the time I got done. National rappers so most of the music was in sidefills with vocals predominantly in the monitors anyway so they were happy but I was not comfortable. My question is if i move the crossover point from 1.2K where it is now will that help out this problem or is this a phase problem and I am just trying to fix it with EQ. I have the tools but don't know how to use them to fix my problem. So any help would be greatly appreciated.

Are your rappers cupping the microphone? Turns a directional mic into an omni.

As for the monitors, more info is needed.

What make/model of 15" woofer, 1.4" compression driver, and what horn?

Are you just using the on board DSP of the XTI amps?

What crossover settings are you using?

Low pass freq.?  Low pass filter type?

High pass freq.?  High pass filter type?

Gains of each?

Best regards,

John
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Montez Carter

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Re: DIY monitors Smaart
« Reply #3 on: January 25, 2012, 04:13:14 pm »

Are your rappers cupping the microphone? Turns a directional mic into an omni.

As for the monitors, more info is needed.

What make/model of 15" woofer, 1.4" compression driver, and what horn?

Are you just using the on board DSP of the XTI amps?

What crossover settings are you using?

Low pass freq.?  Low pass filter type?

High pass freq.?  High pass filter type?

Gains of each?

Best regards,

John
This is what I am using
Woofer: Eminence kappalite 3015/ HPF-60hz 24DB Linkwitz Riley / LPF-1.2K 24DB Linkwitz Riley /polarity +/0 Gain
B&C DE600 1.4" mounted on a B&C ME90 80X60  /HPF-1.2K 24DB Bessel / LPF-14K 24DB Butterworth/ polarity +/-10 Gain.
I am just using the DSP from the crowns(crossover and gain only) and I have not did any parametric cuts as I did them all with the 31 band. And yes I could see them cupping the Mics. The point is I am just now getting into SMAART so the only thing I have pulled up is the RTA but for phase if some one can direct me I can use FFT to look at phase as that is where I am thinking the problem lies. Am I on the right track?
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Paul Tucci

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Re: DIY monitors Smaart
« Reply #4 on: January 25, 2012, 07:24:59 pm »

Am I on the right track?

Montez,

No, you are not on the right track. You are suggesting the solution will be in the phase domain after questionable use of the energy domain. Your investigation needs to proceed logically and with rigor. I suggest understanding before taking action. Moving the crossover might make an improvement or it might cause other problems. An understanding of the problem will lead to the appropriate action. 

Using PSW as a resource is a good idea. The experienced voices can offer good advice.

PT
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Langston Holland

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Re: DIY monitors Smaart
« Reply #5 on: January 26, 2012, 12:34:32 am »

Montez:

With the information provided we can only make guesses at the processing that might be appropriate. Adding the screenshots Timo asked for would certainly help. The measurements should be on-axis with both magnitude and phase plots, though an average of where a musician would stand - left / center / right of the wedge - would also be worth a look.

Even that will lead us to making only somewhat better guesses. The best thing would be to send the wedge around the world to each of us that would like to give you input on the processing so we could do the measurements and tuning using live measurement data. Prepaid of course. :)

But what if you could effectively do that, for free, without sending the wedge anywhere?

You can. It's easy. It's what I have been doing for several years. It allows you to make the measurement once and simply replay it anytime you want to change something.

This Friday I'm going to tune a pair of Danley SH100's and a TH112 that my employees hung in a small auditorium today. Yesterday I made the measurements* while the loudspeakers were at my shop. Tomorrow morning I'm going to do the processing in the electrical domain with a loop through of the measurement recordings through a processed Ashly amplifier. Friday will see a few parametric input filters added for room specific issues.

Anyone that would like to play along can literally do so with a dual channel FFT measurement system and a loudspeaker processor. The 10 second 48k, 16-bit stereo recordings have the loudspeaker measurement on the left channel and the pink noise reference on the right channel. It's helpful if your measurement software can playback a user selected file for its stimulus output. Simply do a loopback of the right output of your audio hardware to the right input. Route the audio hardware's left output to the processor's input and route the processor's output to the audio hardware's left input. Tune away. Both SH100 and TH112 were exactly 26' away from the microphone and the measurement mic gain was identical for both. Thus you can not only EQ the loudspeakers as you'd like, but add crossovers, perform the time/phase alignment (assume for now that the cabinets will be equidistant to the listener) and set the relative levels of the two passbands.

SH100 Measurement Recording

TH112 Measurement Recording

===

In your case Montez, you'd want to make the same kind of stereo recording with the mic at ear position like this:



A smooth cement surface is ideal, but even a 4x8 sheet of plywood in the yard with the wedge in the middle will do nicely in this situation. Low wind is very helpful for stable phase traces at HF, but that's not critical in this application either. You'll need enough level from the pink noise stimulus into the wedge to achieve good coherence and S/N through the range of interest with your two passbands (at least a couple of octaves on either side of the expected crossover point). You should be able to significantly outperform this since the mic will be so close to the source.

One last thought, it's not polite to send full range pink noise through a HF compression driver, so I've supplied a link for you to download a 20 second sample that has been high passed with a 4th order Butterworth at 200Hz. Just use your software's pink noise generator for the woofer.

Pink Noise with 200Hz HP

===

* Before long I'm going to walk through some of the basics of making good measurements. It'll be reflection-free and ground plane based, i.e. ideal, for reasons that'll be covered as well. It's not as easy as it sounds to do correctly, but it's entirely possible depending on the weather and the cops.

Finally, I appreciate and agree with Paul's terse reply concerning the knowledge required to do this correctly. It requires a huge amount of empirical study (time, effort, money) to begin to learn how much you don't know. You're starting well, attend Smaart and Syn-Aud-Con seminars. Syn-Aud-Con has also added some extremely well done online seminars that are much less expensive than live training. Blow things up and post questions in the mean time.
« Last Edit: July 19, 2012, 03:04:09 am by Langston Holland »
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Tim McCulloch

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Re: DIY monitors Smaart
« Reply #6 on: January 27, 2012, 01:07:07 am »

Blow things up and post questions in the mean time.

The Olde Fashioned Way. :D
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Ivan Beaver

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Re: DIY monitors Smaart
« Reply #7 on: January 27, 2012, 05:10:29 pm »

When you say a crossove point of 1.2K is the acoustical or electrical crossover?

If it is electrical, then that is part of your problem.  very rarely is the acoustical and electrical crossover points the same.

Depending on the drivers there may be an over or underlap. 

An RTA is NOT the tool to use.

Smaart is also not something that with a few "pointers" you start to get good measurements AND understand what you are seeing on the screen AND understand how to go about correcting/fixing it.

It is a "process" and the understanding involves lots of experience.

I would start with going through the tutorials that SIA offers.  When you understand that-THEN you move on to the next step.

Don't try to sidestep the learning process.

Screen shots go a long way towards helping people here help you.  Without them, it is purely guess work and no real answers will come of it.
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Mac Kerr

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Re: DIY monitors Smaart
« Reply #8 on: January 27, 2012, 09:20:22 pm »

I would start with going through the tutorials that SIA offers.

FWIW SIA Acoustics is an acoustical consulting company and the original developer of Smaart. The company that developed the current version, and does the training and support is Rational Acoustics.

Mac
« Last Edit: January 28, 2012, 07:51:24 am by Mac Kerr »
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Ivan Beaver

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Re: DIY monitors Smaart
« Reply #9 on: January 28, 2012, 02:00:17 pm »

FWIW SIA Acoustics is an acoustical consulting company and the original developer of Smaart. The company that developed the current version, and does the training and support is Rational Acoustics.

Mac
My slip-sorry.  You are correct.  Old habits ya know.
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