My methodology to designing and building a SQ winning system is simple.
You will need a few things to do this so here is the list:
1. A 1/3 octave RTA of good quality with ability to go down to 1 DB increments.
2. A source capable of reproducing collated PINK noise.
3. A know enclosure/speaker combination with a good response. EG as low as possible and up to at least 3000 Hz.
4. If possible an IMPULSE meter. If you don’t know what it is google “IMPULSE SOUND MEASURMENT”. You should find a kit to build your own.
5. A brain! lol

Stick the enclosure in a car and measure the response of frequency ranges with the enclosure placed in your various speaker positions. Use the RTA to measure the response in car with Pink noise. Then superimpose the response of the car against the response of the enclosure and you’ll see that the car is doing to the response curve.
You now have an acoustic map of your car.
Next Impulse measure the car to find standing waves, cancellations and obvious problems in acoustic response.
The impulse testing will identify areas that effect image while the RTA testing helps you achieve the desired response curve.
With that data you can select drivers, enclosure designs and any adjust your installation to suit the cars response. Its not rocket science, just a basic approach to identify problem areas which you can design for before buying gear or turning your first screw out of the car.
Comments?

in which respect to the system are you talking about as a basic approach i.e. sub box or computer speakers?

*spelling* correlated not collated

appears to be pretty time consuming. obviously only for those who are serious about SQ or are involved in big SQ campaigns. i've never heard of an impulse meter before. im gonna go check it out.



also, i wouldn't be choosing drivers based on the freq response on the car. driver choice for me personally has everything to do with the drivers sound and everything else is secondary.

my approach is to sort out the mechanical side of system before sorting out the sound side. Far easier to address problems earlier than try and compensate later.

Quite close to what I would consider.

I measure:

roof to floor,

door to door,

centre console to kicks,

and therefore I know the standing waves and their harmonics.



I measure for wave guides, various enclosures, and decide on the best medium for audio replay (Hint stereo will not be one of them)



Knowing the standing waves, I calculate the ideal array in conjunction with the wave guide to reduce/eliminate standing waves.



But there again, I don't bother building SQ winning systems.

Can you explain why you wouldn;t select a driver for its response curve to correct for the acoustic response of the vehicle?
Just makes "Perfect" sense to me exploit one drivers characteristics over one that doesn't suit the application.
If you don;t select the "right" gear to start off with then the "everything else" is a patch!
Doing the hard yards up front just makes sense to me rather than "fixing" it later.
But, we all have our own way of doing it I guess. Me, I like knowing what I'm doing before I start rather than crisis manage the problems later.
IMP meters! You guys have never heard of impusle measurement?
Its a burst of sound { very short } so you can measure response BEFORE reflections! Its how you image a system.
Cheers

i got 2 of the best tools around for SQ there stuck on the side of my head

This method is low as you can go to 300HZ, above which reflections no longer matter.

Oh, I'll spell check my posts in future if you find spelling mistakes offensive.


LOL, Good Point!
I'm starting to like you!

because im building a system where the priorities are different. each driver is going to have a particular 'sound' i find the sound i like and THEN worry about response and image because the basis of my enjoyment stems from the sound of the driver. if i dont like the sound, it doesn't matter how well it stages, i still wont enjoy it.



if i wanted "perfect" response and image i'd be spending money on home audio anyway

I prefer to use whats between them, each to their own.

If you consider driver size, and enclosure important (IE building a speaker), then you may wish to reconsider if such a vessel could fit.

sry, i dont understand what ur trying to say. are u trying to say that a particular driver wont fit physically or are u suggesting that the drivers 'sound' will change when installed properly?


if u r talking physically then that misses the whole point why im in car audio not home audio. the fact that i cant get 'perfection' is the reason why i play with car stereos

The major influences an enclosure can have on a driver:

Baffle step diffraction

Altering the system Q

Standing waves (If applicable) in the enclosure

Steradians rating

Enclosure resonance



Building a enclosure can turn an ugly duckling into a swan. It also can have a major detrimental effect. Such considerations should not be taken lightly.

we've covered this before with regards to selecting drivers.



http://www.mobileelectronics.com.au/forums...showtopic=86843



point i am making is i build a system for pure listening enjoyment and therefore i emphasis what i derive the most enjoyment from which just so happens to be the 'sound' of the driver. because we've listend to the driver and have a fair idea of how the dirver will 'sound' in the end.



image and response comes second. if i wanted competition style systems, i'd be in home audio where i can get the best from both worlds

I couldn't agree more. In the end, even the most technically correst sytem can sound crap.
I agree, your driver selection has to include the "sound you like", thats a given.
However, I find it difficult to understand the critical comments with regard to the methods described as a realistic design approuch.
hmmmm, did I miss something?

my comments extended from this





it just came across as tho the only consideration was the freq response of the drivers and that their particular sound had no say.



im glad we agree that the sound is important!!

My bad.
I need a course on how to write! LOL

Have you ever tried this method in your system designs?

I've found knowing more about the environment has helped heaps during the design process. Granted, in the ned there is still a high level of tweeking but I like the idea of having all the right bits in place to look after any unexpected acoustical issues needing to be delt with. EG, I'd rather spent time screwing around with levels than pushing EQ sliders up and down or TA ones for that matter. LOL
Cheers

never had the opportunity to really. i only had a basic system before my 'real' system and i decided i would go all out and learn about audio on the way whilst i built my good system. now that i look back at it, i do wish i had more information, but in saying that, i dont think it would have made any real difference to what components i chose. i love the rainbows over everything i've heard except for maybe a few home systems that dont really sound different, they just do it better than the rainbows.

Is this similar to MLS based measurment.

Yes, kind of.., it doesn't deal with decay.
Simpling its the responce of the car before reflections happens.
So its like an RTA but response is measured in ms
cheers

If you want the response without interference from reflections, use an RTA with hold points, and sine sweep.

I'm really going to have to take ProClass's side here.

I think there are far too many people out there who just get the car they want, then get whatever speakers look good / have a good reputation / sound good in another persons car, and then just throw them into their own car expecting excellent results without really planning or thinking anything through.

They seem to think that all that matters is putting the speakers in their car, and then once they are there they will sound great... and if no then just tune out the problems.

In many cases, it's all a result of a lack of understanding and I know, because I've been there before. You have this thought in your head that "these speakers are so expensive, and everyone loves them, so they must be brilliant...so many people can't be wrong..." but in many cases they are, and those speakers aren't quite so good after all.

The thing is also, that many people can't identify the issues in their system's. I have the gift (or curse, depending on how you look at it) of being able to pick faults in musical reproduction quite accurately. If I hear a track I'm familliar with on a system I can tell you in no time if that system sounds great or is full of problems... and roughly where those problems lie. Runnign a 3-way + sub active setup has helpted tremendously in this regard, because as you play with it more and more you begin to really get a feel for how different adjustments of different frequencies and settings effect the sound, etc. Playing around with RTA's, and having access to other sound systems (home, headphones, etc) can help also in developing 'ears'.

No disrespect intended to anyone (i've been there too), but many people out there just haven't developed the ears or the knowledge to allow them to think things through suitably. Many don't understand what a high fidelity system is supposed to sound like. On top of this, many have limited understanding of how speakers work, the impacts of different physical phenomenon, install techniques and tuning controls.

I can't even begin to compare my knowledge today with the level it was at two years ago, or even a year ago - and the result of that gained knowledge is that now I can far better pre-plan my system(s) in terms of component choice, install techniques, speaker positioning, tuning, etc.

These days, I can predict my system performance with a reasonably high degree of accuracy, and have a very strong understanding of my system's strengths and weaknesses before it's even up and running.

But, if you asked me to do that a year ago, I'd have gotten so many things terribly, terribly wrong - and even today there is no question at all that I stil have much, much to learn - especially in the areas of electronics, craftsmanship (woodwork, etc) and accoustic physics.

As I once did, I think there are a lot of people out there who put a hell of a lot of time, focus and effort into trying to tune out system faults, when a great deal of those faults could probably be avoided with some careful pre-planning, and a little less-conventional thinking.

No offense Muzzy, but is that your Ego talking? With statements like that, I think "put up or shut up" comes to mind. If you can do it, lets see your name on the Pro Street National trophy this year/next year. Until then, lets not go making statements so bold, when you haven't ventured outside your own backyard.

Unless of course, your name is Siegfried Linkwitz, A N Thiele or Richard Small. If thats the case, go right ahead.

i basicly buy stuff and chop my car up.Im guessing i sleep the best at night.

Other than that i have been trying to do what proclass suggests and this is about my 4th go at some door enclosures. I havent got the results i wanted as yet , but had a great time.........cors

Whoa there Wilburrr, lets jump back a step will ya? I understand why you got offended or upset by my post...but let me try to explain myself a little more clearly (I was tired and out of it last night when I posted that).



All I'm saying is that I have the ability to listen to a system and pick out problems with frequency response, timing, resonances and in some cases phase. This isn't because I was born with superhuman hearing, it's because after all of those late night hours tuning in the driveway I've trained my ears to be able to identify system flaws that the typical (less obsessive) person would generally not pick. Being a knowledgable and experience enthusiast yourself, I'm sure you have this ability by now as well - but the average person doesn't.

As far as installing what I'm saying is that many people when doing an install (pro's and enthusiasts, both) simply choose a set of speakers, install them into their car's factory locations, add a little deadening, set the gain on their amps and call it a job. I sure you will agree that the majority (not all!) of system installers take this type of approach, and I think that both ProClass and ablomech would agree with me that it's not the way to get good results from a system.

I think the main reason why people take this approach is because they honestly don't understand audio and accoustics well enough to do any serious pre-planning, and also their ears aren't well trained enough to pick up the flaws. It all sounds 'ok' to them, and 'ok' to the customer, and so they just leave it be and call it a day.



What would this prove? That I have the ability to get the a favourable reaction from a subjective judge, and get my name engraved on a trophy?

With all due respect to the competition and people involved, I don't compete because I feel the need to prove myself. I don't care if I leave a competition with my name on a trophy or a wooden spoon - I go to competitions for the sake of a bit of fun, and the social side of things.

If I go to wagga it will be for the same reasons - to get the opportunity to meet people out of NSW with a common interest, and put a face to some of the names here on CAA/MEA.

I'm working on making it, but i don't know if I'll be able to. I need to first of all negotiate the time off with my boss (which may not be possible), and second of all I need to have my system ready on time (which also may not be possible).

If I can achieve both of these I will be there and rest assured if I'm there, I will compete in Pro Street, not Amateur Street.

Since the old gear came out, I've been planning and tuning this new system for a two seat stage with the clear intention of preparing it for Pro competition - if I end up competing.

u couldnt possilbe say that in any fewer words???/

didnt bother reading due to massive post, there shoud be limits on this type of thing...

I think people should ask themselves some pretty basic questions.

Why do these speakers produce excellent/adequate music reproduction in my house, and suck in my car?

Perhaps then, you might appreciate the magnitude of ProClass's thought processes.

Until then, keep swapping out drivers, power amplifiers and head decks and cables, perhaps one day you really will reach the end . (Hamster running in a wheel)

Nope! This will NOT do what a IMP does. Far from it.
To achieve these measurements the sound burst must so short that a full wave length can not reflect before being measured.

As sure as there is air, there are different methods being employed to achieve the desired acoustical results.
The intention of my post was to introduce some to the old school sciences used to build some of the world best SQ systems. I am not suggesting that this method is the only way or the right way for that matter but simply sharing tried and proven methods.

I do hope that there are a few out there that can and will give it a go. It worked for me in the past and I can't see it not working now. I believe the hardest part of this method is in interpreting the data collected. It took me a few goes before I got great results.

cheers

i dont think anybody is disagreeing with ProClass

There, I made it a little shorter for you baby

Couldn't agree more! At University if you write 10% over the limit you get penalised heavily (and most markers won't read it after the limit). I think if you can't say what you want in concise ammount of words then don't bother saying it


On that note, keep it on topic Loving the discussion between Pro CLass, Abmolech and Matt

Hey, Im not disagreeing with Proclass either, but I think that if you're really serious, you need more then just your ears.

Audio is a science, and replication of audio is pure engineering. Understanding the technical aspects of it all, whether clearly and distinctly audible or not, is IMO very important.

Your ears can be trained to detect problems you never heard 6 months ago, but the right instrumentation will pick it up first time. If you want to do it right first time, dont trust your ears to guide you, because it will just mean you will be picking more and more flaws as your brain develops and learns. You're system will never be finished, because as you continue to pursue understanding and knowledge, you will continue to develop your skills.

If you use the correct instrumentation first time, if you understand audio acoustics, if you continue to read the various whitepapers around the place on human perception and auditory information, then when you finally perform your installation, you can get it 95% correct first time. The rest is just tuning, which is also a fairly understandable science now too.

Measure and understand the environmental factors before installation. Put the correct drivers (each one individually measured), in the proper positions and enclosures, in the correct manner, first time. Apply the correct electronics behind them. Then perform impulse measurements, FFT's, RTA, sweeps, waterfalls etc. to 'see' timing misalignments, frequency response anomalies, phase coherence, group delay (etc. etc.). Once you can see it, you can then start to account for it (note I didnt say eliminate it). Then you'll never have to listen for it, because its never there.

Muzzy, I agree with a lot of what you have said in your previous statement, but I just thought your statement about elevating your level of knowledge and skill above the 'average person' was very arrogant. I could say Im special because I have a size 13 foot, and a 65cm head, but until I actually do something to impact the community, it means nothing. Sure you have enough more knowledge then 50% of the audio community, but there is 50% of the community out there that know more then you. We all need to understand that we are still playing in the sandbox, and people like Abmolech and Proclass are trying to elevate us (and themselves ) out of it.

What I find extremely frustrating is people claiming their ears are superior to anyone elses. They arent. Your brain might be more clued in, because of the training and development you've had, but given the same exposure, someone else will also have the same 'skill' you currently maintain. You're lucky, not special.

I believe both Proclass and ~thematt~ have good methods. I simply expect mine to be easier and less (humanly) fallible.



Standing wave are caused when the frequency is mixed.

There are some precursors to this phenomena.

They have to share the same space (well doh)

They have to meet on a factor of quarter, IE 1/4, 1/2, 3/4, unity.

The have to be the same frequency.



For you to effected by this, you need to be close to the quarter points. (Distance from a reflected surface or speaker)

How does this help us?

If we measure the distance between two parallel surfaces we can predict (accurately) the first standing wave and its harmonics (multiples of the frequencies)

Lets use an example.



The distance between two parallel surfaces, say the two doors= 1.5 metres.

Sound travels at 345 metres per second. Therefore the first standing wave is 345/1.5 = 230 Hz ? Well it is ONE of the waves, but since it can happen on a quarter, it is 230 /4 = 57.5 Hz.

Some of you may recognise this as a troublesome frequency?,

Factors of it, 57.5, 115, 172.5, 230 etc etc. The severity of these are determined by how good of a blocker, and parallel these surfaces are.

Perhaps another?

The dreaded floor to roof. = 1 meter, therefore, 345/1/4 = 86.25 Hz.

And the factors, 86.25, 172.5, 258.75, 345 etc



Now some of you may have noticed two on the same frequency, 172 .5 Hz...

Ever wondered why these features so strongly in your dips?

Point

A tape measure and a calculator can equal or beat RTA etc measurements.

Don't get me wrong, an RTA is worth its purchase, but I would spend it on an accelerometer first. (the only real difference is an RTA uses a microphone for air and accelerometer uses mass meter they both use capacitance difference across a diaphragm)



The next question is how to you combat these?

So how do you combat these?

I have 2 noticable holes in my frequency response.

160-200 hz

630-800 hz

Does not matter what speaker size is in the car. 5.25", 6.5", 9" these holes are still there.

So whats the trick.?

Clue,

EQ and speaker aiming ain't going to solve it. They could embalm it, but thats it.

May be i should buy a car that has a flat frequency response.

ummm.... ah.... ummmm
standing wave on 1/4, 1/2 and 3/4? ummmmm........
naaaaaa, not in my book.
Granted, nodes can cause peaks and dips but in my book are not what I call a standing wave.
To me a standing wave is full wave length reflection. Node reflections IMO are the acoustical signiture of the room and are not always unwanted. Standing waves on the other hand always are.
But then like we have all agreed, ears are our own.
IMO the only way to fix standing waves as I have described is a very very tight notch filter. An EQ effects to great a range of frequencies and results in a gap in response. To me an EQ is the the very last method to employ to fix a bad design.

So far I have really enjoyed this thread and I hope it keeps going!
I'm hoping that those who keep coming back and reading to post questions, ideas and comments.
The whole idea behind this thread is to revisit old school practices and re-apply them today.
cheers

Hey E320, when you find one PM me themake and model!

Interesting idea, does a room have a flat frequency response?







Well if you believe standing waves only occur at unity, then, you would have to have to parallel surfaces 2.9 metres apart. Get measuring... Clue your windshield and rear shield are not parallel.

Another tip, if it is a genuine(?) standing wave, logically it will be audible only 1.45 metres from that reflective surface.

Most likely the floor to roof reflection. Generally speaking the internal door trim are not very good blockers (reflectors).



Have I mentioned how much I like wave guides and arrays...(sutile hint? )

Some other tips, helm holtz resonantors...your not the first person to have this problem, if you have time, reading Gothic and Romanesque church design might be interesting.

mmmk... i'm unfamiliar with alot of the terminology here, but i see abmolech started discussing standing waves. ProClass says he's hoping for some questions, so i'll start off with a basic one, which will most likely lead to more basic ones.



I'd like to know what the affect of a standing wave is? I'm thinking about it, and based on abmolech's description and example using two parallel door drivers, it's a case that at given frequencies the sound from each of the two speakers meets in such a manner that they are basically 180 degrees out of phase with each other, hence cancelling each other out, resulting in a certain frequency that is significantly softer than the rest? Is that a somewhat accurate description or am i completely off track here?

They grow up so fast

Bang on, how about the opposite, what if they meet in phase?

Yep they sum. This is the reason why it is at every quarter of a cycle.



Now where would you have to be to hear this null or summing, in relation to the speakers? IE If you had your ear close to a speaker, would you be able to hear this phenomenon?

would angling woofers in doors help flick standing waves??/

cos then they would no longe be parralel would they??

no, the wave 'diffracs' from the driver, so u would still end up with parallel waves

How do waves propagate?

In expanding spheres, assuming uninhibited, and enough energy.

This is where a wave guide/baffle pays large dividends. If the baffle is as large or larger than the wave, then it only has to propagate into half a sphere, and since a sphere takes 6 dB, you gain 3 dB. (IE only 3 db needed)



Let as assume therefore the door mount is propagating in half a sphere. (It would be a first for car audio, build a decent baffle for once ) The only other variable (OK there are other "baffles") is the driver diameter or "shape" itself.



Beaming

Beaming is when the driver cone diameter is significant in relation to the frequency.

IE an 8" driver (200 mm) starts beaming at 345/200*1000(It is in meters) =1725 Hz.

What does this mean?

Well the whole surface of a cone "radiates" (hence radiating driver) and the surface can be considered an array of "points". The points at largest distance apart (200 mm) start to create standing waves.

So what if we were to use an array?

Well it would start beaming at different frequency's. Across the width of a single driver, lets say 8", would be 1725, but because we have multiple drivers in array it would start beaming earlier across the length of the array. If there were two 8" drivers it would start beaming at 862 Hz. If there were three, 345/200*3*1000 = 575 Hz.



So angling drivers only effects the off axis response, which is primarily determined by the driver cone diameter. Since off axis response is a frequency versus amplitude variation, it won't help much. (There will be some phase change near the beaming frequencies, IE acoustic crosstalk)

What we want is phase versus frequency variation, so we can change the timing of the standing waves.

The science of acoustics is in depth and you can quickly become entrenched in solving the riddle of your car’s acoustics. Much of the science is rooted in home audio, theater, etc. The application of these sciences to the car environment can quickly become extremely complex and boggle the mind. It has been my experience that many of the conclusions drawn from the home/theater environments do not necessarily hold true in a car. While the science is correct the car presents an extremely complex acoustical environment. The science was not derived from such circumstance.
The application of what I call my basic design approach is simple. Before anything can be recommended with respect to design you need the acoustical map of your car. While I have explored this methodology in pursuit of SQ the same methods can be applied to SPL. For SPL one would exploit the peeks of your acoustical map while in SQ we try to achieve a smooth response free of peeks and valleys.
Fair?

And how is this done?

Did I hear someone say passive cross overs!

Nope a decent DSP will always run rings around a decent passive crossover. There is nothing a passive can do (well OK they can saturate and add more distorsion ), that an active crossover cannot equal or beat.



Tact, DEQX and Lakes might give a clue as to what a DSP can do.

Which is half the reason why I hate SQ comps. Everyone's ears have different response's. My mate with ear damage has had his ears tested and compared to the average healthy persons ears has a significant 4dB drop around a certain frequency. If he sets his car up for a supposed "optimum sq setup" he might feel it is lacking something.

Just having a rant but sometimes it seems as though people are building there cars for other people's ears not their own.

Precisely why I only compete in comps for the social side of it, and to try to support the industry.

I don't compete just to win trophy's or the hearts of judges, because if you ask me that all means nothing in the grand scheme of things. It's gotta be for you!

Muzzy have you ever actually stopped critically listening and just laid back and enjoyed the music? im not stirring mate, but sometimes I find myself just constantly critically listening, and I think to myself, why cant I just enjoy what I actually set all this up for? which, essentially, is the actual music itself.
Im lately trying to just relax, stop worrying about all the technical aspects of why it doesnt souned as good as the perfectionist in us demands it to, and just lose myself in the actual music.
Im extremely interested in Pro classes methods to set up a proper SQ system, I'll definately be trying exactly what he has described, along with thematts, yours and abmolechs additions and suggestions for myself.
But sometimes I wonder if the average Joe, with a stock system, isnt actually enjoying his music alot more than us SQ guys are....

Just a thought I've been pondering lately.

I think this has been one of the most informative threads I've read in a very long time, I love the engineering anology thematt used, it definately breaks the mystery and black art of setting up and tuning and puts it all into a perspective thats quantifiable, and above all achievable, with the correct knowledge.
Awesome topic, thread and quality of posts..

I totally agree Wh33lzz

I think the time I enjoyed myself most listening to car stereos in the last few weeks was when I listened to someone elses car. Admitidly it was a bloody noice sounding system, but with someone elses car I think you concentrate on what is great about that system, and what is great about the music, as opposed to what is missing and not so good.

the other times I've enjoyed myself is listening to music with someone else in the car that really liked the tunes...

interesting...

Matt