To Tune or Not To Tune?

[richard_crl032]

Am sharing some ICE tuning experiences here for general discussion. Comments are welcomed.

 

1. Amp gain matching not optimized to harness the full potential of the source, amp and drivers. The advent of advanced DSP today allows users more flexibility and control in sound reproduction. However, poor understanding of and the reliance on instruments to achieve balance and tonality, short of human ears to fine-tune, often leads to boring sound reproduction. In one use case, the Helix DSP source (volume) was maximised but there was utter lack of dynamics and resolution. It turned out that the gains on amplifiers were very conservatively tuned and did not match the source output.

 

2. Not optimizing the crossover points and the slopes to maximize the full potential of the drivers. The academic and conservative use of crossover points and slopes very often reproduce defined sound stage and neat presentation. However, such practices also generally produce less engaging music. While the overall presentation is neat, it became less realistic and doesnât engage the listener over a period of time. Do use tech spec of the speakers as reference and in doing so, attempt to fully exploit the bandwidth in which the drivers are capable of reproducing. This allows the full potential of the sound system to be presented.

 

3. Generally, the presentation of soundstage in some cars is confined BETWEEN the speakers rather than OUTSIDE the speakers. This may sound normal to some of us, especially when most tuning today is geared towards achieving certain competition guidelines as benchmark. However, the overall spirit of sound reproduction becomes artificial and confined to a certain space. The goal of sound reproduction should be that of achieving as wide a sound stage as possible without losing the focus. Sound should appear to come from everywhere other than the speakers themselves. Best is that we can tune the soundstage to the extent that the speakers are âtransparentâ. In my opinion, soundstage should never be defined or limited by the size of the car windscreen and the depth of the car bonnet. The objective is to make your car cabin THE space in which the recording is made.

What signal frequencies do you employed for the different drivers of sub, midbass, midrange and tweeters ? Obviously you do not use 1k hz for sub that you may use for midrange since it will output nothing or you do by avoiding setting crossover points ?

 

 

Hi Sarong1,

 

Missed a related query on essentially multiple drivers set up and gain matching as follows:

 

For some purist, it is said that gain on processor for different channels should not have to be cut back to protect the max signal which does make sense. However, this may be unavoidable when using different amp with different sensivity/impedance to resort to turning down gain instead of max gain without distortion for some channels ... do you submit to seen using time alignment instead to handle this situation as I have my doubt or simply do so i.e. cut gain on processor?

 

Cheers.

 

Richard

[richard_crl032]

My humble opinion, I will ask for the tune to be for the staging and imaging at ear level and centre of the dash.

 

SQ wise, it's difficult to achieve an accurate sound, because there's no way to know how the "original sound" is like, since we are not there at the recording studio or concert.

 

Besides, when recording, sound gets "coloured" as it passes thru the different equipment from the mic, cables, mixer, etc.

 

So tune to a level that is to your personal liking will do. ICE is very subjective just like art.

 

For woofer, i prefer it to be set at 50hz. I forgot about the slope and phase since I've been off ICE for many years. I like a bit of boomz in my music. 40hz is too tight and 60hz is too boomy.

 

For mids and tweeters, I leave it to the tuner to tune. Generally I prefer warm sound instead of bright and clear.

Hi Jaffa,

 

Seems you had resigned to having audio workshops to do your tuning nowadays ... fully understandable.

 

However, I have quite extensive experience in last 10 yrs + with them and found nothing but disappointment too often even though I tried to push them but requesting my car/audio setup to join emma competition under their name .. keke !

 

This may incur another few hundreds but ok since I spent 10s of thousands already .. at the least, it will be days of concerted efforts by ws tuners instead of just hours before sending you off.

 

End of the day, you can spend 50k on best equipment, cablings and installation but it boils down by a large margin on final tuning ... ws tuners unfortunately runs a biz and perhaps only some really try if you are their kaki and supporter.

 

On your mentioned colored sound and having a bit of boom , it is certainly not wrong to have it to your preference since it is your hard earned $ but if you are into home audio and wife/kids up to grade 8 piano certification, you may want what is near to what was recorded by the artists and recording studio. However, this is admittedly also an elusive dream but just hope to get nearer there since even best home audio are far from the "real thing" .. tube vs solid state, full range driver vs dedicated drivers vs open baffled vs boxed design vs electrostatics panels etc. etc.

 

Nowadays, I just try to do a bit here a bit there, including the painful task of learning and trying to tune on my own even though I am educated in physics and sciences but no longer stress myself out in search of perfection ... latest being dsd playback in car and dumped dedicated SQ headunit to moved to android headunit for especially internet radios that offer so much more music that my 2TB hdd or hundreds of CDs that to me is still much betta than these lossless files except perhaps limited releasesnof dsd recording of different technologies that may be worth trying.

 

I also hope to get into more complex processing like dirac live room correction via minidsp since traditional car processor tuning is somewhat limited but sure, final tuning is still by ears on preferred shifts in the response curve .. our ears are simply 1000x more advanced and uniquely yours than whatever even best stereo mic used in such tuning/correction attempts. This opens again another big can of worms as some purists avoid any form of eq and believes it is doable which I certainly do not agree.

 

Cheers.

 

Richard

[Sarong1]

Hi Sarong1,

 

Missed a related query on essentially multiple drivers set up and gain matching as follows:

 

For some purist, it is said that gain on processor for different channels should not have to be cut back to protect the max signal which does make sense. However, this may be unavoidable when using different amp with different sensivity/impedance to resort to turning down gain instead of max gain without distortion for some channels ... do you submit to seen using time alignment instead to handle this situation as I have my doubt or simply do so i.e. cut gain on processor?

 

Cheers.

 

Richard

 

Hi Richard,

 

I learned from the "older" generation of tuning where we aimed to get at least 80-90% of the signal from the source via the volume knob (e.g. Clarion 9255, D1 and D2) and we attempt to "clip" the processors (e.g. Audio Control EQT) before scaling back slightly. That was done before we even hear the sound from the drivers. Then we matched the EQT's output to the amplifiers before we used our ears to fine-tune.

 

We didn't always have the luxury to use scopes and we detest paying installers then when we weren't sure if they could really scope to our expectations. I don't believe in using scope to tune, up till now.

 

I don't think TA is used to deal with source input/output. Rather, results from TA-ed sound/music may affect the gains on different drivers. I have experienced cases where when the soundstage is TA-ed correctly, the midbass and tweeters became too pronounced, hence the gain on the channels were scaled back or increased. This was despite the gain being matched using scope at the beginning.

 

So there is really a difference between scoping it correctly in the first place or install vis-a-vis the gains after tuning. And it is important to gain-match the source inputs and amp output in order to aid tuning.

 

Sarong1

 

 

[richard_crl032]

Hi Richard,

 

I learned from the "older" generation of tuning where we aimed to get at least 80-90% of the signal from the source via the volume knob (e.g. Clarion 9255, D1 and D2) and we attempt to "clip" the processors (e.g. Audio Control EQT) before scaling back slightly. That was done before we even hear the sound from the drivers. Then we matched the EQT's output to the amplifiers before we used our ears to fine-tune.

 

We didn't always have the luxury to use scopes and we detest paying installers then when we weren't sure if they could really scope to our expectations. I don't believe in using scope to tune, up till now.

 

I don't think TA is used to deal with source input/output. Rather, results from TA-ed sound/music may affect the gains on different drivers. I have experienced cases where when the soundstage is TA-ed correctly, the midbass and tweeters became too pronounced, hence the gain on the channels were scaled back or increased. This was despite the gain being matched using scope at the beginning.

 

So there is really a difference between scoping it correctly in the first place or install vis-a-vis the gains after tuning. And it is important to gain-match the source inputs and amp output in order to aid tuning.

 

Sarong1

 

 

Hi Sarong1,

 

Thanks for the comments and advice.

 

Just to ensure that I am not mistaken:

 

- you scaled back or increased on the gain of amp or processor ?

- if on amp, then no longer ideally amp gain matched ?

- if on processor, then signal quality differs between channels and will linearity between pairs of drivers not be affected ?

 

Not sure why not use scope for specific application .. we din have previously but now easily accessible and repeatability/reproducible instead of "kung fu" which will doubtlessly varied day to day or fatigue even for a master tuner like you, right ? This is especially when I had scope my old alpine F1 HU which basically does not clip at 100% volume measure out of also old F1 H900 processor still being used at 0db or full signal output .. cutting it at 80 or 90% wun hqve wasted some SQ ?

 

On your last paragraph, can you further elaborate ? It is then to you opinion to gain match amp or gain match processor ? Seems you are a proponent to ignore gain match processor and amp with source being already fixed at max volume and tune by ears to adjust gain of amp to less ideal match during tuning ? This is essentially same query in the 1st paragraph I think ....

 

Hope I am clearer this time with my query and pls also advise on initial query on the frequencies for gain match of different pairs of drivers playing different frequencies.

 

Cheers.

 

Richard

Edited September 23, 2018 by richard_crl032

[Sarong1]

Hi Richard, allow me to also lend more clarity to my earlier thoughts in BLACK fonts.

 

- you scaled back or increased on the gain of amp or processor ?

[comments: those days, we scaled back (reduce) on the processor, using the voltage peaking indicator LED light on the processor as some rudimentary form of indication.]

- if on amp, then no longer ideally amp gain matched ?

[comments:the amp gain depended very much on the source output, it the source output was higher than the amp, I think it would be natural to reduce? I didn't have the experience of low source output though so can't really comment :) ]

- if on processor, then signal quality differs between channels and will linearity between pairs of drivers not be affected ?

[comments, those days still got passive crossovers, so the linearity can only be close but not perfect.]

Not sure why not use scope for specific application .. we din have previously but now easily accessible and repeatability/reproducible instead of "kung fu" which will doubtlessly varied day to day or fatigue even for a master tuner like you, right ? This is especially when I had scope my old alpine F1 HU which basically does not clip at 100% volume measure out of also old F1 H900 processor still being used at 0db or full signal output .. cutting it at 80 or 90% wun hqve wasted some SQ ?

[comments: I need to clarify that it is definitely good to first scope before the equipment to balance things out but you must understand that scope wasn't really easily accessible those days. So I learned to use other methods albeit hard ways, to tune. You are right that it is available nowadays, so please scope it before commencing tuning. But for me, I am used to and have developed my own heuristics ways to tune, so it is pretty difficult to pen down.]

On your last paragraph, can you further elaborate ? It is then to you opinion to gain match amp or gain match processor ? Seems you are a proponent to ignore gain match processor and amp with source being already fixed at max volume and tune by ears to adjust gain of amp to less ideal match during tuning ? This is essentially same query in the 1st paragraph I think ....

[comments: My opinion has always to gain-balance the source, processor and amplifier. I do not have any preference for any form of gain balancing. But learning turning using my own ears have allowed me to grasp manual tuning faster than using equipment. That said, please scope to achieve gain balance at the initial stage of install and after equipment are run-in.]

 

I must agree that our ears get fatigued over prolong period of tuning. But our ears will eventually get fatigue anyway over long time of listening to music even if it is scoped right? So I allowed myself to immerse in manual tuning using my ears. and that was how I trained myself in the earlier years. How did I know how instruments should sound, and how do they sound in different environments? I attend regular music sessions and pay close attention to details while listening to the instruments...and remember them. Those are my reference points. Having said, tuning need some imagination too so my perception may differ too. 

 

I have also mentioned before that when I was invited to listen to members' car, I would sit inside to enjoy the soundstage presentation liked by the car owner himself. It is akin to going to art gallery to watch artefacts and paintings. I see myself as being there to appreciate. Of course I will have my opinion. I have my way of "painting" the soundstage.

 

I have hard time trying to pen down my tuning thoughts but am making attempts anyway should anybody be interested to read.

 

For those who are keen, there is always regular sgcaraudio.net meetups held monthly, where we get together to chit-chat, enjoy each other's new gadgets or even tuning experience.

 

Regards

[richard_crl032]

Hi Richard, allow me to also lend more clarity to my earlier thoughts in BLACK fonts.

 

- you scaled back or increased on the gain of amp or processor ?

[comments: those days, we scaled back (reduce) on the processor, using the voltage peaking indicator LED light on the processor as some rudimentary form of indication.]

- if on amp, then no longer ideally amp gain matched ?

[comments:the amp gain depended very much on the source output, it the source output was higher than the amp, I think it would be natural to reduce? I didn't have the experience of low source output though so can't really comment :) ]

- if on processor, then signal quality differs between channels and will linearity between pairs of drivers not be affected ?

[comments, those days still got passive crossovers, so the linearity can only be close but not perfect.]

 

Not sure why not use scope for specific application .. we din have previously but now easily accessible and repeatability/reproducible instead of "kung fu" which will doubtlessly varied day to day or fatigue even for a master tuner like you, right ? This is especially when I had scope my old alpine F1 HU which basically does not clip at 100% volume measure out of also old F1 H900 processor still being used at 0db or full signal output .. cutting it at 80 or 90% wun hqve wasted some SQ ?

[comments: I need to clarify that it is definitely good to first scope before the equipment to balance things out but you must understand that scope wasn't really easily accessible those days. So I learned to use other methods albeit hard ways, to tune. You are right that it is available nowadays, so please scope it before commencing tuning. But for me, I am used to and have developed my own heuristics ways to tune, so it is pretty difficult to pen down.]

 

On your last paragraph, can you further elaborate ? It is then to you opinion to gain match amp or gain match processor ? Seems you are a proponent to ignore gain match processor and amp with source being already fixed at max volume and tune by ears to adjust gain of amp to less ideal match during tuning ? This is essentially same query in the 1st paragraph I think ....

[comments: My opinion has always to gain-balance the source, processor and amplifier. I do not have any preference for any form of gain balancing. But learning turning using my own ears have allowed me to grasp manual tuning faster than using equipment. That said, please scope to achieve gain balance at the initial stage of install and after equipment are run-in.]

 

I must agree that our ears get fatigued over prolong period of tuning. But our ears will eventually get fatigue anyway over long time of listening to music even if it is scoped right? So I allowed myself to immerse in manual tuning using my ears. and that was how I trained myself in the earlier years. How did I know how instruments should sound, and how do they sound in different environments? I attend regular music sessions and pay close attention to details while listening to the instruments...and remember them. Those are my reference points. Having said, tuning need some imagination too so my perception may differ too.

 

I have also mentioned before that when I was invited to listen to members' car, I would sit inside to enjoy the soundstage presentation liked by the car owner himself. It is akin to going to art gallery to watch artefacts and paintings. I see myself as being there to appreciate. Of course I will have my opinion. I have my way of "painting" the soundstage.

 

I have hard time trying to pen down my tuning thoughts but am making attempts anyway should anybody be interested to read.

 

For those who are keen, there is always regular sgcaraudio.net meetups held monthly, where we get together to chit-chat, enjoy each other's new gadgets or even tuning experience.

 

Regards

Hi Sarong1,

 

Thanks thanks !

 

Guess I have to experiment more and burn more petrol but tuning car is really PITA and so much efforts.

 

It is my wish for some quick reproducible and repeatable methodology for a not perfect but a decent >90% tune to maximise the $ spent on equipment and installation which many bros spent on.

 

This will free them from the dependence from the "king fu" of installers especially since my own experience is that there is run in period especially with new equipment as well as changing equipment that will requiring continued retuning but yet installers will not have time or interest after collecting payment :(

 

Perhaps my next steps after getting the scope for 1 yr+ is to find a 200A 12v DC source to avoid burning petrol as well as get cost effective minidsp process which allows the use of dirac live room correction application ... wonder if my unused 1200W single rail computer psu will be suitable with theoretically 100A capacity or get another one to power up my bigger system....lol !

 

Cheers.

 

Richard

Edited September 23, 2018 by richard_crl032

[Sarong1]

Thanks for contributing your experiences and thoughts too, Richard.

 

It is always easier to leave it to the "pro" to tune but the question has always been, at what cost and expense? 

That said, should catch up with you soon as I remembered not having enjoyed your system before...

 

Regards

[Meemee]

Newer dsp offer auto tune ...

For the eq

 

Did a A/B tester

..

As good as the champ tunner .....

:)

[Kermit]

The “Mysteries Behind Time Alignment in the Car”

 

Hi guys, Kermit here.  Older folks would remember me.  It has been ages since I contributed to this forum.  This is my little “present” to ICE enthusiasts after being in exile for years. Perhaps this would set us back on the thinking track once again and hopefully gain more personal insights.

 

The topic is on “Time Alignment” (TA).  Other aspects such as Crossover settings, gains matching, hardware employment etc, while related, will not be the focus here.

 

There are perennial problems one may often face in TA.  Why is my soundstage slanted? Why is my soundstage not wide/high/deep enough?  Why are there stray frequencies floating and drafting in the car?  Why do I not get a consistently correct soundstage when I switch between tracks and sources?  Sound familiar?  I will attempt to explore these questions here.

 

What is Time Alignment?

 

TA, as its name suggests, is trying to align all the sounds produced by the speakers to reach the listener’s ears (and brain) at the same time. In this way, just like sitting at the sweet spot in home audio, or headphones, or IEMs, one should get a perfectly-synced stereo image of the recording.  The effect is that one would be able to localise each instrument (and overall stage) at its place and space, with the correct focus/size and energy, and the correct tonalities meant to be presented in the recording.

 

However, the car has its unique inherent challenges.  The listener is not seated at the centre.  Speakers are not symmetrically facing towards the listener. The car is a confined space and has many surfaces that absorb or reflect soundwaves, e.g. windows, seats, dashboard etc.  All these complicate matters (sound reproduction).  I'll try to be as simple as possible in my explanation, so most people may understand.  Also, note that I’m not addressing issues related to the acoustic environment in the car.

 

But, TA aims to mitigate the above problems.  How?  The DSP can now try to apply a time delay to each channel (corresponding to each speaker) so that the aim is the make each speaker’s sound arrive at the same time to the listener (Driver). In other words, we make sure those speakers that are nearer play a bit slower and therefore waiting for the further speaker to reach us. Sounds simple?  If it is, I wouldn’t be writing this.

 

If we can now imagine a bit.  In home audio or headphones, all the speakers are of (1)same distance, (2)facing the same direction, and even (3)pointing directly at the listener (on-axis).  If we can replicate this environment in the car, we could use no TA.  Perhaps one can defeat all TA and try to sit the back row centre in the car to get a feel.  No need TA.

 

Time Alignment and Phase

 

It is now time to introduce the idea of “Phase”. Back to secondary school physics, remember how a sine wave looks like, with ups and downs cycles?  A complete wavelength goes up from the x-axis, comes back down cut the x-axis, then goes down and back up ending back at the x-axis.

 

There is an intimate relationship between time and phase.  Remember TA is about time?  So, if we delay the production of a sine wave by some milliseconds, at any given same point in time on the x-axis, the Phase of the wave is different.  Can you picture this?  Sorry I can’t draw here….

 

So, by applying delay to sound, you are also introducing phase changes to it.  Do not confuse this with polarity, or phase inversion deliberately applied to the speakers.  In the world of TA, phase changes are applied to all the frequencies in the range so that in relation to each other they are almost phase coherent with each other with respect to time. In TA, you call this group phase or delay. On the other hand, in deliberate phase inversion, e.g. by switching the +- poles of the speaker, all the frequencies are inverted in phase with no respect to time.  

 

Bear with me.  With this technical wisdom, now, you know that each speaker in the car is at different distance, and facing different directions. What does this mean?  For phase changes without time consideration, you already have sound arriving at different phases without TA.  i.e. speakers that are facing their sides at you (e.g. right side woofer in door) already arrives at a 45deg angle out of phase.  Some other speakers could be at other angles and your subwoofer is probably 180deg off.  So, you have all coming at you at difference phases.

 

How to TA?

 

Remember that TA also shift phases?  The aim of TA is therefore to make all sounds arrive at the SAME PHASE.  I emphasize this because, Phase is a relative thing in sound.  They don’t have to be correct; they just have to be coherent.  You can well have all sounds at 180deg out of phase and they will still sound correct because you do not get funny things happening such as phase cancellation and peaks.

 

So in practical sense, what should you do?  Study the angles of the speakers.  Have an idea what the original “phases” are.  When you apply TA values, remember that they are applied with the assumption of speakers being on-axis.  This would be a good start.  You can measure the distances of each speaker and input them according to how your DSP works. At this stage, you should get a rough centre image there.  But sound may still be diffused or drift because they are slightly out of phase due to speaker angles.  Move the TA values for Left and Right channels in corresponding magnitudes up and down such that the delay difference between the L/R channels remain roughly the same.  At some point, sound will become more focused, balanced, and more energy both at the centre and at the sides.  Try it, feel it. 

 

Then, do the same for all speaker sets (Low, mid, highs) in L/R pairs.  Please try to ignore the figures on your DSP and do not attempt to understand them.  Use your ears.  The reason why the figures are so far-off between each range sets is because of speaker angles!  When you now combine all the sets of speakers….here’s the fun part.  Remember they are firing at different angles? This is give you a hint of whether you should apply more or less delays to each set, so that the phases are brought to become all coherent to the listener.  Do this keeping one set constant and work on aligning another set to it.  Do this until u get a nice and focused soundstage.

 

I apologise for the fuzziness in this.  Perhaps hands-on would help in understanding this.  In summary, TA is about getting phases together, with the help of time delays to shift phases so that they all work together.  We need to do this because we have so many speakers responsible in producing different frequency ranges and firing all over the place. So far, this is my humble attempt at explaining the scientific portion of a proper TA in the car.  

 

TA is both an Art and a Science.  The Art is your good ears.  Some people don’t even know what they’re doing with TA but their ears bring them there.  Some people, use scopes and measurements and all….yet they still can’t get it.

 

Cheers! Have fun.

 

Oh….copyright reserved.  I welcome constructive discussions and comments.

 

[Sarong1]

Thanks Kermit for the wonderful contribution and detailed write-up.

 

Indeed, putting together a set of sound system in car may well be adequate for most music lovers. But to some others who want to push music enjoyment further, getting the stereo balance and correct sound stage are possibly the next natural thing to do. And we do so with what technology offers us - DSP and time alignment features.

What gives the correct benchmark? Do we TA to what some audio competition standard demands?  IMHO, the correct benchmark is how picky your ears are. You TA to what you want the sound stage in the car to be. You TA to your ears and your listening comfort. You paint your own picture.

 

How much to TA and to what extent, is indeed an Art and Science.

[Kermit]

Thanks Kermit for the wonderful contribution and detailed write-up.

 

Indeed, putting together a set of sound system in car may well be adequate for most music lovers. But to some others who want to push music enjoyment further, getting the stereo balance and correct sound stage are possibly the next natural thing to do. And we do so with what technology offers us - DSP and time alignment features.

 

What gives the correct benchmark? Do we TA to what some audio competition standard demands?  IMHO, the correct benchmark is how picky your ears are. You TA to what you want the sound stage in the car to be. You TA to your ears and your listening comfort. You paint your own picture.

 

How much to TA and to what extent, is indeed an Art and Science.

 

Thanks for journeying together.  I have learnt much from all the brain-wrecking discussions many years ago and recently. 

 

Indeed, If one is to be picky, he/she must pick up the paint brush and paint the picture himself/herself.  This is the objective of my article. lol.

[Meemee]

Thanks for journeying together. I have learnt much from all the brain-wrecking discussions many years ago and recently.

 

Indeed, If one is to be picky, he/she must pick up the paint brush and paint the picture himself/herself. This is the objective of my article. lol.

Can pick up own screw driver ???

[Kermit]

Can pick up own screw driver ???

 

I do it.  So why not? 

[richard_crl032]

The âMysteries Behind Time Alignment in the Carâ

 

Hi guys, Kermit here. Older folks would remember me. It has been ages since I contributed to this forum. This is my little âpresentâ to ICE enthusiasts after being in exile for years. Perhaps this would set us back on the thinking track once again and hopefully gain more personal insights.

 

The topic is on âTime Alignmentâ (TA). Other aspects such as Crossover settings, gains matching, hardware employment etc, while related, will not be the focus here.

 

There are perennial problems one may often face in TA. Why is my soundstage slanted? Why is my soundstage not wide/high/deep enough? Why are there stray frequencies floating and drafting in the car? Why do I not get a consistently correct soundstage when I switch between tracks and sources? Sound familiar? I will attempt to explore these questions here.

 

What is Time Alignment?

 

TA, as its name suggests, is trying to align all the sounds produced by the speakers to reach the listenerâs ears (and brain) at the same time. In this way, just like sitting at the sweet spot in home audio, or headphones, or IEMs, one should get a perfectly-synced stereo image of the recording. The effect is that one would be able to localise each instrument (and overall stage) at its place and space, with the correct focus/size and energy, and the correct tonalities meant to be presented in the recording.

 

However, the car has its unique inherent challenges. The listener is not seated at the centre. Speakers are not symmetrically facing towards the listener. The car is a confined space and has many surfaces that absorb or reflect soundwaves, e.g. windows, seats, dashboard etc. All these complicate matters (sound reproduction). I'll try to be as simple as possible in my explanation, so most people may understand. Also, note that Iâm not addressing issues related to the acoustic environment in the car.

 

But, TA aims to mitigate the above problems. How? The DSP can now try to apply a time delay to each channel (corresponding to each speaker) so that the aim is the make each speakerâs sound arrive at the same time to the listener (Driver). In other words, we make sure those speakers that are nearer play a bit slower and therefore waiting for the further speaker to reach us. Sounds simple? If it is, I wouldnât be writing this.

 

If we can now imagine a bit. In home audio or headphones, all the speakers are of (1)same distance, (2)facing the same direction, and even (3)pointing directly at the listener (on-axis). If we can replicate this environment in the car, we could use no TA. Perhaps one can defeat all TA and try to sit the back row centre in the car to get a feel. No need TA.

 

Time Alignment and Phase

 

It is now time to introduce the idea of âPhaseâ. Back to secondary school physics, remember how a sine wave looks like, with ups and downs cycles? A complete wavelength goes up from the x-axis, comes back down cut the x-axis, then goes down and back up ending back at the x-axis.

 

There is an intimate relationship between time and phase. Remember TA is about time? So, if we delay the production of a sine wave by some milliseconds, at any given same point in time on the x-axis, the Phase of the wave is different. Can you picture this? Sorry I canât draw hereâ¦.

 

So, by applying delay to sound, you are also introducing phase changes to it. Do not confuse this with polarity, or phase inversion deliberately applied to the speakers. In the world of TA, phase changes are applied to all the frequencies in the range so that in relation to each other they are almost phase coherent with each other with respect to time. In TA, you call this group phase or delay. On the other hand, in deliberate phase inversion, e.g. by switching the +- poles of the speaker, all the frequencies are inverted in phase with no respect to time.

 

Bear with me. With this technical wisdom, now, you know that each speaker in the car is at different distance, and facing different directions. What does this mean? For phase changes without time consideration, you already have sound arriving at different phases without TA. i.e. speakers that are facing their sides at you (e.g. right side woofer in door) already arrives at a 45deg angle out of phase. Some other speakers could be at other angles and your subwoofer is probably 180deg off. So, you have all coming at you at difference phases.

 

How to TA?

 

Remember that TA also shift phases? The aim of TA is therefore to make all sounds arrive at the SAME PHASE. I emphasize this because, Phase is a relative thing in sound. They donât have to be correct; they just have to be coherent. You can well have all sounds at 180deg out of phase and they will still sound correct because you do not get funny things happening such as phase cancellation and peaks.

 

So in practical sense, what should you do? Study the angles of the speakers. Have an idea what the original âphasesâ are. When you apply TA values, remember that they are applied with the assumption of speakers being on-axis. This would be a good start. You can measure the distances of each speaker and input them according to how your DSP works. At this stage, you should get a rough centre image there. But sound may still be diffused or drift because they are slightly out of phase due to speaker angles. Move the TA values for Left and Right channels in corresponding magnitudes up and down such that the delay difference between the L/R channels remain roughly the same. At some point, sound will become more focused, balanced, and more energy both at the centre and at the sides. Try it, feel it.

 

Then, do the same for all speaker sets (Low, mid, highs) in L/R pairs. Please try to ignore the figures on your DSP and do not attempt to understand them. Use your ears. The reason why the figures are so far-off between each range sets is because of speaker angles! When you now combine all the sets of speakersâ¦.hereâs the fun part. Remember they are firing at different angles? This is give you a hint of whether you should apply more or less delays to each set, so that the phases are brought to become all coherent to the listener. Do this keeping one set constant and work on aligning another set to it. Do this until u get a nice and focused soundstage.

 

I apologise for the fuzziness in this. Perhaps hands-on would help in understanding this. In summary, TA is about getting phases together, with the help of time delays to shift phases so that they all work together. We need to do this because we have so many speakers responsible in producing different frequency ranges and firing all over the place. So far, this is my humble attempt at explaining the scientific portion of a proper TA in the car.

 

TA is both an Art and a Science. The Art is your good ears. Some people donât even know what theyâre doing with TA but their ears bring them there. Some people, use scopes and measurements and allâ¦.yet they still canât get it.

 

Cheers! Have fun.

 

Ohâ¦.copyright reserved. I welcome constructive discussions and comments.

Hi Kermit,

 

Nice !!

 

To your last statement, what about using scope, room correction software etc. and get there faster before tuning by ear ? Then truly science and art, right ?

 

Think this kung fu aka art approach of TA is killing car audio hobby and industry.

 

Cheers.

 

Richard

[Kermit]

If it gets you there faster, do it. But you must never forget the art part.

[Sarong1]

Hi Kermit,

 

Nice !!

 

To your last statement, what about using scope, room correction software etc. and get there faster before tuning by ear ? Then truly science and art, right ?

 

Think this kung fu aka art approach of TA is killing car audio hobby and industry.

 

Cheers.

 

Richard

 

Richard, I think this "Kung Fu" approach IS keeping the car audio industries & hobby very much alive!

 

People are willing to pay to have their systems tuned. Hence, it is timely that we (hobbyist) also learn some Kung Fu to do some "social good".

[Kermit]

I would say....understand the science, apply and express it in art. Appreciate it after.

 

Painters also need to know what paintbrush to use, which materials and colours can mix etc....before they paint.

[richard_crl032]

Richard, I think this "Kung Fu" approach IS keeping the car audio industries & hobby very much alive!

 

People are willing to pay to have their systems tuned. Hence, it is timely that we (hobbyist) also learn some Kung Fu to do some "social good".

Hi Sarong1,

 

No leh .. I beg to differ.

 

Even hardcore enthusiats like me but without kungfu become indifferent liao cos given up.

 

Hobbyists like yourself, bro kermit etc. are a dying breed.

 

Sad to say but just take the death of once active sgcaraudio group and taking into considering current much cheaper headfi option especially with tiong gears like latest dsd dsc for sgd100 that can sound much betta without mentioned paying big $ to installers for equipment, installation and tuning .. their young ears are also appreciative of higher sound quality.

 

Imho, unless there are formal "social" classes with practical hands-on lessons like in usa on both repeatable and reproducible "science and art" that can be payable for sustainability, it is a futile attempt with only pockets of success.

 

http://installerinstitute.com/

 

Cheers.

 

Richard

Edited October 9, 2018 by richard_crl032