Tonality vs RTA

[Jscoyne2]

. This is because you hear direct sound differently than you hear reflected sounds but the RTA picks up reflected sound the same as direct sound so what you hear and what you see may be different when crossing above the beaming of a driver. If you EQ to compensate for the lack of direct sound then you may hear it differently then what the RTA shows. This could lead to the perception of a bright sound or harsh sound but every car will be different.

I never considered that. Interesting.

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[blockrocker]

For arguments sake, if I'm fantastically on axis with the mids can beaming be removed from the equation? Like if I'm less then 15 degrees off axis and the charts Show less than 3db difference between the two angles. Or are crossover suggestions from manufacturers considering that you can't really get two drivers perfectly on axis, more often than not?
I hope I asked that question properly. ��

[Jscoyne2]

So the thing about a car you have to remember is that you're tuning reflections far more than you would in a home. You're tuning reflections just as much as you are tuning direct sound, if not more.

So having your speaker radiate the same spl omnidirectionally will make tuning easier and it'll sound better.

Its kind of hard to explain scientifically but from experience and my opinion. Tonality comes from direct sound. Envelopment of stage and presence comes from reflected sound. You want that radiated sound to be the same everywhere or your timing and stage cues that your ears are listening for, get wonky when amplitude (and phase) is different in different directions.

Im sure someone else can explain it better.

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[blockrocker]

That makes sense to me. Dumdum has been explaining this to me as well. Im still training my ears to be able to tell the difference between direct and reflected sound. It makes sense though, that if all the sound has been duplicated the same from the left and right, the reflection becomes invisible to the direct sound. Or something to that effect.

[Jscoyne2]

That makes sense to me. Dumdum has been explaining this to me as well. Im still training my ears to be able to tell the difference between direct and reflected sound. It makes sense though, that if all the sound has been duplicated the same from the left and right, the reflection becomes invisible to the direct sound. Or something to that effect.

I doubt anyone can tell the difference between direct and reflections. Atleast not consciously.

Sound quality in regards to beaming has a lot to do with phase. Phase changes as amplitude changes.

A good speaker will have its on axis and off axis response be as close to the same as possible. So its phase will be close to the same after beaming. This is super super important when you consider that you want your crossover phase to be the same on and off axis so your speakers sum correctly. Reflections will still cause issues but the better the original FR on/off axis, the better your overall response should be when it hits your ear.

What we're trying to accomplish in a listening environment is an untainted source directly from the sound source to our ear. But we get reflections/diffraction and and speaker distortion in the way.

Reflections are not evil. Ill say that again. Reflections are not evil. Everything we have ever heard is direct and indirect sound summing in our ear canal and our smart brains being able to tell the difference between the two. Cars just happen to have reflections that need a ton of eq to tame. There are tuners and builders that know how to position the speaker so that they get reflections that give them a better sense of space. Am i one of those people? Nopee but someone is.

If you're in an auditorium and you listen to a choir. That auditorium was designed to give you a very specific sound based on its reflections.

That's why i say reflections give you a sense of space in a car. HOWEVER. Close reflections near the speaker will make it so you can locate the source of sound. This is Great for our survival instincts and terrible for creating an illusion of a stage in a sealed environment like a vehicle.

You really want to minimize diffraction and super close reflections as much as possible as they are creating new sound sources everytime they hit a surface. Here's a great visual aid.

http://www.silcom.com/~aludwig/images/diffdem.gif

As for distortion. There is a whole ton of research on the difference orders of even and odd distortion and what is pleasing to the human ear. Subwoofers have been proven to sound warmer and louder with more distortion to them.

Tl,;dr There is more to consider than just its frequency response because of beaming.

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[blockrocker]

This is dynamite food for thought. I really appreciate the responses. Also the reading material, if you have more, I'm game. Starting to get pumped for another tuning session this weekend. I get the first days of the year off work, woohoo.
Very cool gif too, great visual aid.

[jtrosky]

A little off-topic, but if anyone is looking for a good tuning device (aka laptop), check out a used Lenovo Yoga 2 Pro or Yoga 3 Pro on Ebay. They are 13.3" touch-screen devices that also allow you to fold them all of the way back to make it into a tablet of sorts. Lately, I've been using mine in "tablet" mode, which is awesome - you get the benefit of a 13.3" screen, but can actually just set the device on your lap! No chance of blocking sound waves from the speakers when measuring in REW and/or trying to find a spot to set a regular laptop. VERY nice setup for this!

You can find the Yoga 2 Pro (or even the Yoga 3 Pro) in decent shape for under $250 used on Ebay. These devices are pretty amazing (super thin and super light). Yoga 3 Pro is like 1/2" thick and weighs 2.5 lbs. The Yoga 2 Pro is about 3 lbs. Most come with 8gb of RAM and a 128gb or 256gb solid-state drive. Processors can be i3, i5, i7 or m5. I got an i7, 8GB RAM, 256GB solid-state Yoga 2 Pro for like $230. Screen is like new and rest of device is in pretty good shape.

[SkizeR]

To address OP first post and general tuning tips.

We tune to a curve because of IID(mostly this) and ITD need to be matched. And the general curve we follow(all house curves are basically the same with small changes in roll off and dips in midrange) is based on the munson curve and our varying sensitivity to varying frequencies.

That sensitivity actually changes based on spl levels. Also interestingly, crossovers actually change based on how much power you give them(I've never tested that but do remember reading it.) Most likely because of heat of passive coils. Maybe inductance. Honestly. Idk why.

If you tune to at 85db. And it sounds well and good. When you turn it up. Your crossovers change slightly causing a peak or dip at the xo point. Your hearing sensitivity also changes varying on frequencies. This is why it sounds bad at high volumes to you. I think we're more sensitive to high freq at higher spl.

The best way to tune is probably to do it at levels you normally listen to it at. I wear earplugs when i run my sweeps.

When I tune. I normally use as little EQ bands as possible with wide Q filters and get everything varyingly close together between left and right. Then i sit there with freq specific mono pink noise. 250hz. 350hz. 450hz. Ect and i start adding filters until each one sounds like it is on the center of my dash. This can be tricky as you get into the ITD range. It may take some t/a adjustment and Eq adjustment back and forth to get this right.

Rew is an Excellent program and great for beginners to learn and understand but never underestimate your greatest tool. Your own damn ears.

Also getting the crossover roll offs on each driver to sum perfectly to each other will do WONDERS to your stage and overall tonality. Use Jazzis tuning companion to get perfect crossover slopes to eq to based on your particular curve.

You will need Excel for this. It won't work on any excel-similiar program. The macro coding is different.

https://www.diymobileaudio.com/threa...4#post-5761031

Look at Wikipedias equal loudness curve page



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House curves are not based on the equal loudness contour, or munson fletcher curve. They are based on how drivers interact with the room they are in and how our ears/brain perceives it

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[JCsAudio]

For arguments sake, if I'm fantastically on axis with the mids can beaming be removed from the equation? Like if I'm less then 15 degrees off axis and the charts Show less than 3db difference between the two angles. Or are crossover suggestions from manufacturers considering that you can't really get two drivers perfectly on axis, more often than not?
I hope I asked that question properly. 😉

Blocker, It still matters although less so. Reflected sounds obviously mix with the direct sound and that stays pretty much at an even basis so long as you are low passing your drivers with a diameter that coincides with a good polar response or to keep it simple under when driver beaming starts. It’s just better to have all the reflected sounds match the direct sounds as closely as possible, even if the driver is on axis to make tuning an easier affair. Remember, because the automobile is such a small environment with hard surfaces, there will be reflected sounds all over the place despite the fact that you also have drivers that are on axis. If those reflected sounds become much different than the direct sound than you may have tuning issues, phase issue, and as you move your head around you may notice the sounds changes.

Think of that driver beaming like a flashlight directing light in front of it but nothing around it. Now think of a floodlight with a broad spectrum of light evenly distributed throughout a wide angle and area. Now that is what your sound looks like with a driver playing above its beaming point (flashlight) vs one playing below its beaming point (floodlight). You tell me which one is better?


This is turning out to be a really good discussion here. Lots of very good commentary coming from you guys! Jscoyne2 and SkizeR, thank you for your contributions.

[blockrocker]

Thank you JC. I've always found it really beneficial to my learning curve to have as many knowledgeable people answer the same question as possible. Eventually its gets broken down into digestible pieces for me to absorb. I tend to be a monkey see-monkey do learner, so I feel comfortable with trial and error but need some extra time to wade through the technical and theoretical stuff. This forum caters to both very well, so its a nice place to fill holes in my skills.

I'm realizing more and more, that most of my stereo problems are from bad habits formed early in learning. Just plain wrong "facts" that I took at face value. Things like: playing your mid range as wide as possible, keeping my HP filters as low as possible despite information suggesting the opposite, random crossover points with no consideration for beaming, distortion, etc. Piss-poor speaker placement and general install techniques.

When I got back into this hobby after a long time away, I figured I knew what I was doing and that an EQ system couldn't be harder to do than a ground pounder. I knew what a crossover was and used a DMM to set gains (unlike at 20) and since I knew how to install, it would be a piece of cake. Needless to say I have been majorly humbled, but at the same time my eyes have opened to a whole new world of audio possibilities. I re-fell in love with car stereo's because I had so much to learn. Now I feel like I did about them at 17 - can't get enough!!!

I appreciate the time everyone is taking on these forums. Not just for me, but everyone seems very cohesive.