Go Back   Team-BHP > Under the Hood > In-Car Entertainment


Reply
 
Thread Tools Search this Thread
Old 28th December 2009, 23:47   #16
BHPian
 
yayaati's Avatar
 
Join Date: Jan 2005
Location: Faridabad
Posts: 186
Thanked: 0 Times
Default

Thanks LBM for explaining it via diagram

Now i am also sure that whats On and Off Axis

The one which i was using in my car, where the tweeter were on the A pillar using the flush mount is Off Axis

And the one which You and Zuchero are using with the custom pods are On Axis

I have heard both the setups and IMO the On Axis one have more detail than the Off Axis.
yayaati is offline   Reply With Quote
Old 29th December 2009, 01:40   #17
Senior - BHPian
 
Invinsible's Avatar
 
Join Date: Nov 2006
Location: Bombay
Posts: 1,257
Thanked: 60 Times
Default

A sphere doesn't help to get away with the reflection but with the diffraction. A tweeter mounted on a baffle will face more amount diffraction than a sphere would. Sphere simply reduces the amount diffraction that occurs compared to baffle. Tweeters installed on A-pillers are prone to have more reflection than having them on sail panel / doors / kick panel. But diffraction on the A-piller is less than what would happen on doors or sail panels. With reduced diffraction and placing them 90 deg off-axis on the it makes up some what against the reflection coming off the windscreen. But, most importantly it's the nature of the tweeter that also matters here. Some tweeters by nature deliver bright sound, some are warm, some sound laid back when played them in free air. At times, reflection caused by the windscreen is good in case of some tweeters where it aids in wider dispersion. For instance Morel's dome tweeters, they sound very detailed irrespective of whether you play them on or off-axis. But, what makes a difference in on-axis is the amount of space it adds to the sound, vocals have more depth and it stays cleaner even on high volume. For now, mine are installed A-piller with 90 deg off-axis. But, here's what I have done for the time being. I cut the tennis ball in 2 equal halves and placed them behind the tweeter magnet, it acts as an enclosure to the tweeters. Result, well instantly I realised that the tweeters were sounding more lively, it adds like a reverb effect, more detailed and added more space to it. Had to cut down to -3 db on them.
Determining what size of sphere enclosure is needed for one, depends on what freq. you would limit them to. With reduced diffraction the result will be less amount peaks and deeps in freq response resulting in much smoother response. Peaks and dips in freq. range adds to the way tweeter behaves when played with higher volume. With more amount of peaks and dips caused by diffraction, tweeter may land up sounding harsh when being pushed to the limit. Diffraction is a matter of concern with freq. above 1khz. It can make the music sound harsh on higher volume even when playing the best tweeter available in the market.
Cure to diffraction is not just about adding the sphere enclosure to the tweeter. But, it's also about the placement and where the tweeter is pointing. Not all like the sound coming from it. We are so accustomed to the traditional way of installation and the way it sounds that at times some really don't see any sense going for it and prefer the traditional way. But, for me, it sounds in away where it gives me a feeling that all the highs coming just from one place or off the center and not from left or right corners.

The plan is to use the sphere, mount it on custom fabricated stand that I am making which would be 4" off the dashboard, 4" away from the windscreen, 2-3" away from the A-piller, pointing / facing both the tweeter towards the rear view mirror. Stand is already under fabrication, once it's done will be under going for powder coating. And finally mount the Sphere enclosure on it. I have already tested this position. The result were much better. Could hear every detail in vocals. It added a lot more space / presence to the overall sound. As of now they are running under passive, but soon will be going active with these with 100 RMS on each. Apart from this, it's always better to play around with the phase. You will be surprised as to the difference it could make.

Greenh0rn: A sphere has no edges and usually the diffraction occurs on the edges as the music from the tweeter starts dispersing. Once it reaches the edge of the baffle, there are peaks and dips that occur in the freq. response. This could make one believe that the tweeter are brighter or they lack detail. Note the tweeter quality and characteristics also plays the role here. Some tweeters when played on-axis tend to sound much brighter and harsh, that is because one it's the characteristics, two there is both diffraction and reflection making the sound for the person to conclude that indeed the tweeter is bright by nature. But, in some case if the tweeter is of higher quality it can make them sound detailed. In other words reflection cannot be controlled in car environment but diffraction can, it can be reduced to some extent where reflection doesn't play the spoilsport and muddies the sound, in a way some reduced reflection result.
This can also reduce the much need of the individual EQ required to make it sound balanced.

GILL: Dyn's are power hungry and also slightly less efficient. I would say if you really want Dyn's to sing, play them in Active with loads of power. There will be day and night difference as to the way they will sing.
Invinsible is offline   Reply With Quote
Old 29th December 2009, 02:51   #18
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Quote:
Originally Posted by Invinsible View Post
GILL: Dyn's are power hungry and also slightly less efficient. I would say if you really want Dyn's to sing, play them in Active with loads of power. There will be day and night difference as to the way they will sing.
Hmm...I agree. But our Zuchero singh is confused. He is running the setup passive. He says the HU (HX-D2) he has have a cross-over point of 2 khz or 2.5 khz. But the passive cross over is cut at 2.2 khz. So when he goes from passive to active the tonal qualtiy of the speaker changes !!!!
low_bass_makker is online now   Reply With Quote
Old 29th December 2009, 05:39   #19
BHPian
 
Crimson's Avatar
 
Join Date: Jun 2009
Location: Pune
Posts: 222
Thanked: 0 Times
Default

I am currently installing a 3-way component set. This thread has been very useful and as I like a brighter sound, I would go in for an ON-Axis installation ofr the tweeter on the A column. I am considering angle as 0 degress - as in each tweeter pointing directly back to each seat.

My midbass driver would be Off Axis in the stock location in the doors.

For the Mids, they would go in the Quarter glass pannel. Please suggest, should these be 90 degrees OFF AXIS or 30 degrees ON AXIS. I cannot mount them like the tweeters at 0 degrees ON AXIS. Please advice.
Crimson is offline   Reply With Quote
Old 29th December 2009, 06:27   #20
Awaiting Email Confirmation
 
Join Date: Jun 2009
Location: South Africa
Posts: 185
Thanked: 11 Times
Default

Quote:
Originally Posted by Crimson View Post
I am currently installing a 3-way component set. This thread has been very useful and as I like a brighter sound, I would go in for an ON-Axis installation ofr the tweeter on the A column. I am considering angle as 0 degress - as in each tweeter pointing directly back to each seat.

My midbass driver would be Off Axis in the stock location in the doors.

For the Mids, they would go in the Quarter glass pannel. Please suggest, should these be 90 degrees OFF AXIS or 30 degrees ON AXIS. I cannot mount them like the tweeters at 0 degrees ON AXIS. Please advice.
if i was going three way this is more like how i personally would install the midrange and tweeter (pictures taken randomly from installations ive seen on the net)

Name:  PICT0182.jpg
Views: 9890
Size:  80.2 KB

from another angle

Name:  PICT0184.jpg
Views: 3744
Size:  66.0 KB

or a different but similar situation

Name:  hondacityvtec4thinteriorpaneldashboardcustompillartweetermidbass.jpg
Views: 4913
Size:  28.7 KB

Quote:
How does that help- in reducing reflections etc.? And is cutting a tennis ball into two and using the two halves for mounts really helpful in getting any more detailing from the tweeters?
as Abhishek(invincible) has explained the purpose of the tennis ball is not to combat reflections but rather edge diffraction. In fact an oval shape would better ie like an egg with the longer side toward the back of the tweeter but a sphere is a start toward that

in terms of reflections, most are harmful but there are ways that you could use them toward your advantage but remember anytime you place a tweeter on the pillar it doesnt matter much on the orientation of the tweeter because the output does not beam ie most tweeters will still have an output that is spherical in nature so you will get reflections in some form or the other from the windscreen and glass is hard hence the reflections can become fierce, so if installing tweeters in the A-pillar you need to experiment with the angle that can minimise the effect of those reflections

obviously if you hear the sound as raspy or hollow which is a sure sign that "comb filtering" is occurring and it might benefit you to change the angle

but many people prefer tweeters in the kick panels because there is no windshield there to reflect the sound wave since there is normally carpet in the kick panels which serves as a secondary purpose to absorb the waves that you dont want reflected ... whilst higher up on the pillars you can treat the dash with a dash mat but you cannot do much with the windscreen

in a car its all about installing speakers in locations that will be a compromise, kick panels create less reflections and minimize pathlength differences hence why lots of people like those locations but if you have effective T/A and if you are experienced in tuning and/or are willing to live with the compromises involved you can pull off an a-pillar install

about the edge diffraction here is a thread over at Diyma that will explain it for you without us having to repeat a lot of what it is all about, here they show you the benefits of flush mounting the tweeter onto the baffle as well as chamfering the edges of the baffle to reduce edge diffraction

Improve Your Soundstage for $2 - DIY Mobile Audio (click me)

Quote:
He says the HU (HX-D2) he has have a cross-over point of 2 khz or 2.5 khz. But the passive cross over is cut at 2.2 khz. So when he goes from passive to active the tonal qualtiy of the speaker changes !!!!
crossing over 200hz above or below the original passive crossovers midpoint wont cause too much harm since that 200hz is only around 1/10th of an octave at that point, the usable frequency response is definitely more than a full octave above that 2000hz before you reach the speakers resonant frequencies so shifting the crossover point is not a huge problem especially moreso if you change the slope ie with the passive crossover the mid uses a slope of 6db/oct and the tweeter uses 12db/octave

i tried a crossover point for both the mids and tweets fully active at 2000hz with a slope of 24db/octave and it worked fine. To further this the tweeters were up on the a-pillars off axis and the mids in the stock door locations

Last edited by naughty001 : 29th December 2009 at 06:37.
naughty001 is offline   Reply With Quote
Old 29th December 2009, 06:49   #21
BHPian
 
Crimson's Avatar
 
Join Date: Jun 2009
Location: Pune
Posts: 222
Thanked: 0 Times
Default

Thanks Naughty001. This is exactly what I had in mind with the exception that the mids be more off axis as apposed to what is shown in the image. Fitting the mids at this angle would be quite a task.

But i guess if On-Axis for mids is done well they would sound a lot better.
Crimson is offline   Reply With Quote
Old 29th December 2009, 10:46   #22
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Here is my placement with the DLS. No intention of marketing just knowledge share !!!

Off-axis
Tweeter placement and Pod?-dscn3648-medium.jpg

On-Axis
Tweeter placement and Pod?-dsc_8239-medium.jpg
low_bass_makker is online now   Reply With Quote
Old 29th December 2009, 11:02   #23
BHPian
 
Gill's Avatar
 
Join Date: Aug 2007
Location: Mohali
Posts: 699
Thanked: 12 Times
Default

Where are the horns?
Gill is offline   Reply With Quote
Old 29th December 2009, 11:02   #24
Senior - BHPian
 
Invinsible's Avatar
 
Join Date: Nov 2006
Location: Bombay
Posts: 1,257
Thanked: 60 Times
Default

+1 to what Naughty has mentioned. It wouldnt matter much whether you play the midbass at 2 or 2.2khz. It all depends on what slope you use on midbass and tweeter infact active gives you that flexibility as to where you want to cross your drivers depending on the location, your taste and preferences. What will make them sing beyond this is the individual power they would be getting. There are some who may not stick to xover points set on passive when going active and prefer something as per their liking. Usually when playing the midwoofer in doors the driver is 90 off-axis and freq above 2 khz starts rolling off. Which is one of the reason why most passive xover are designed with 1.8 to 2.2 xover point. So lets even if you cross the midbass at 1.8 to 2khz with LP at 12db and get tweeter to cross at 2khz at HP 12db octave. This would still cover every bit of music. Ofcourse the options are many.

Crimson: Usually it is preferred to let the midrange and tweeter work closely together as they cover most part of the music and detail. Mount the tweeter at the same degree you would With the midrange. 30 to 45 deg off-axis should work well. Overall its all about tuning and If you have independant left & right EQ you should be able to get best result out of it. The installation pic Nitin has shown looks good. Anything similar to it will work better.
Invinsible is offline   Reply With Quote
Old 29th December 2009, 11:16   #25
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Quote:
Originally Posted by Gill View Post
Where are the horns?
Outside under the bonnet...LOL.

This is a very old pic may be a year old. I have not put any latest as it might lead to marketing !!!!
low_bass_makker is online now   Reply With Quote
Old 29th December 2009, 13:10   #26
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 22,503
Thanked: 3,882 Times
Default

Quote:
Originally Posted by low_bass_makker View Post
Also in the off- axis install the left tweeter would be approx 60 degree from the listener and the right tweeter would be 30 degree from the listener. .
this is if the listener is in the left passenger seat na?

Quote:
Originally Posted by Invinsible View Post
A sphere doesn't help to get away with the reflection but with the diffraction....but diffraction on the A-piller is less than what would happen on doors or sail panels..

Result, well instantly I realised that the tweeters were sounding more lively, it adds like a reverb effect, more detailed and added more space to it. Had to cut down to -3 db on them.

The plan is to use the sphere, mount it on custom fabricated stand that I am making which would be 4" off the dashboard, 4" away from the windscreen, 2-3" away from the A-piller, pointing / facing both the tweeter towards the rear view mirror.

Greenh0rn: A sphere has no edges and usually the diffraction occurs on the edges as the music from the tweeter starts dispersing. .
Quote:
Originally Posted by naughty001 View Post
as Abhishek(invincible) has explained the purpose of the tennis ball is not to combat reflections but rather edge diffraction.

obviously if you hear the sound as raspy or hollow which is a sure sign that "comb filtering" is occurring and it might benefit you to change the angle

but many people prefer tweeters in the kick panels because there is no windshield there to reflect the sound wave since there is normally carpet in the kick panels which serves as a secondary purpose to absorb the waves that you dont want reflected ...

moreso if you change the slope ie with the passive crossover the mid uses a slope of 6db/oct and the tweeter uses 12db/octave

i tried a crossover point for both the mids and tweets fully active at 2000hz with a slope of 24db/octave and it worked fine. To further this the tweeters were up on the a-pillars off axis and the mids in the stock door locations
1. sphere have edges too. In fact in a sphere the edge is exactly the same all around so all the diffraction will occur at the same frequency. It can be argued that an infinite baffle does not have an edge...othewise any baffle - circular, rectangular or square or any other polygon will have edges (whre the baffle ends).

2. the reason why tweeters mounted in free space (that is why spheres are used) have improved imaging (in most cases) is because when a high frequecny wave emnates from the dome the baffle smears the wave and there are more than one source of the sound (due to the smear from the baffle). by eliminating the baffle one eliminates the smear. Difraction however is a different animal.

A sphere is good but a tapered tube like used by B&W is even better. Many years ago I did some experiments on SS's 9900 tweeter..we removed the faceplate and backplate and opened up the back chamber (thee 9900 has no ferro fluid to wrry about) to a tapered tube and found that this really helped the tweeters resonance peak (traditionally ferro fluid is used to damp this peak as well as improve power handling) without the side effects of ferro fluid (because ferro fluid acts like a damping agent it tends to make tweeters sound less alive and robs tweeters of some of their delicacy).

While the DIYMA article has correctly identified this effect I believe they have not named it correctly. If you see post 4 of the same article and follow the link to Linkwitz Lab's website you will get a beter picture of what is considered difraction and how it is measured. To quote Linkwitz "Much is hypothesized, little is proven and much is overrated when it comes to diffraction"

Baffle Step (as explined in the other link in post 4) is a very different animal. Again baffle step will exist as long as there is a baffle (circular, square, or anyother polygon) it is only the nature of the step that will change. see post 36 on the same DIYMA thread.

3. Now getting back the question of on-axis response and off-axis response almost every dome tweeter I know (we are not talking about planars, leafs, ribbons, etc..) has a response that fall off rather sharply off-axis. Few tweeters have much response 60 degrees off axis above 10kHz or so. That does not imply that a tweeter that has no roll off off-axis is better than tweeters that do. There is evidence to prove that disperson control is essential in creating a realistic image (most of these experiments are in home audio but the principles apply to car audio as well - after all our ears and brain are the same).

I dont see how reflections of any sort can help hf response. reflections (like dfraction) will almost always create multiple sources for the same frequency thereby creating (to various degrees) a comb filter effect across the hf band. However the effects of reflections should be more severe than difraction as the ammount of energy that a dome tweeter has 20-30 deg off axis is much more than 70-90deg. off axis.

Before we go about installing midranges and tweeters on A pillars or kick pnales please remember that these cars are 'daily drivers'. It is not advisable to limit your visibility or put speakers where they are likely to get damaged.

BTW I see Invisible and Nitin (Naughty) are active on DIYMA! wish I had time to read that whole thread.

Last edited by navin : 29th December 2009 at 13:36.
navin is offline   Reply With Quote
Old 29th December 2009, 14:33   #27
Awaiting Email Confirmation
 
Join Date: Jun 2009
Location: South Africa
Posts: 185
Thanked: 11 Times
Default

agreed with most of what Navin has also said but with one caveat. We can never fully control all the factors but we can try to minimise the effects of certain factors, so things like edge diffraction etc can never ever be eliminated yet we can make their effects smaller than usual by doing these certain small things

Quote:
I dont see how reflections of any sort can help hf response. reflections (like dfraction) will almost always create multiple sources for the same frequency thereby creating (to various degrees) a comb filter effect across the hf band. However the effects of reflections should be more severe than difraction as the ammount of energy that a dome tweeter has 20-30 deg off axis is much more than 70-90deg. off axis.
for sure, but once again we know that in the environment of a car with all of its reflective plastic and leather surfaces what we are after is to minimise the effects of the reflection since we can never eliminate them so there are certain speakers with certain response characteristics as well as other parameters that can aid in minimizing the effects of these reflections which is in a perverse way what i was alluding to that certain tweeters can help

higher frequencies will definitely reflect more hence some speakers are designed so that they can be placed off axis but at this point they will be reflecting a lot more high frequency energy off the windscreen than other speakers would which is why they were designed to roll off at a steeper rate off axis so you can install those off axis and tonally at least keep some form of high frequency energy even if its compromised in the sense that its a reflection rather than a direct sound

i havent been a fan of using the windscreen in this manner but reflections from a windscreen are used in all sorts of different ways for example Gary Biggs uses his JBL 660GTI set in a way that the windscreen becomes a top extension of his waveguide on the tweeter whilst the horizontal dash extends the lower portion of the waveguide - so he was more or less using it to force some type of reflection .... and it seemed to have worked because he won IASCA world finals with it three years in a row if im not mistaken

Quote:
Before we go about installing midranges and tweeters on A pillars or kick pnales please remember that these cars are 'daily drivers'. It is not advisable to limit your visibility or put speakers where they are likely to get damaged.
thats another restriction that tends to spoil what can be done in a car ie you have to be practical but whilst A-pillars can decrease visibility if they are installed mostly ff axis in this respect you should be fine BUT to me in terms of damage i reckon its way more potentially damaging to use kick panels

in a two way setup the tweeter pod will be mostly small enough to not restrict outward visibility but in a three way it does tend to become a small problem but most guys who are running active with enough time alignment facilities would tend to use the tweeter only uptop and then use the midrange in the kick panels and the midbass in the doors or also kick panels but for me i would tend to kick those speakers to "bits" which is why i dont personally use kick panel installs even though they are more ideal than pillar locations for speakers in terms of pathlength differences

i wish they would award points for practicality or may even remove points for impracticality in competitive (SQ) car audio because then people would be forced to look for more innovative ways of installing these things more practically

@LBM ... very nice install sir. wish i could see your Horn install. Maybe if i ever visit India i might pay you a visit and have a listen to it.

Quote:
BTW I see Invisible and Nitin (Naughty) are active on DIYMA!
Im active on over 30 forums, though only a few of them are audio ones. Audio is a small hobby whereas im very active on computer and computer overclocking and modding forums because computer hardware is more my field
naughty001 is offline   Reply With Quote
Old 29th December 2009, 21:47   #28
BHPian
 
Join Date: Feb 2005
Location: New Delhi
Posts: 393
Thanked: 39 Times
Default

Thanks Navin, LBM and Nitin...now I am completely sold on using a Cosco tennis ball as my tweeter mount, LBM bhai can you guide me with proper installation advise - getting a fabricated stand etc. I can come to Faridabad anyday to discuss and get things going!

Wow man Nitin, if this is what you end up doing with audio when it is a small hobby, i'd very much like to know how far do you play with overclocking/modding PC rigs! Which games do you play?
greenh0rn is offline   Reply With Quote
Old 30th December 2009, 06:42   #29
Awaiting Email Confirmation
 
Join Date: Jun 2009
Location: South Africa
Posts: 185
Thanked: 11 Times
Default

Quote:
Originally Posted by greenh0rn View Post
Thanks Navin, LBM and Nitin...now I am completely sold on using a Cosco tennis ball as my tweeter mount, LBM bhai can you guide me with proper installation advise - getting a fabricated stand etc. I can come to Faridabad anyday to discuss and get things going!

Wow man Nitin, if this is what you end up doing with audio when it is a small hobby, i'd very much like to know how far do you play with overclocking/modding PC rigs! Which games do you play?
sorry for going so but im not much of a gamer, so i dont play a lot of games. Heres a small link to my last computer project which i began to describe in the computer section here at Team BHP

http://www.team-bhp.com/forum/gadget...e-modding.html (Computer and Case modding) (click me)

my computer speakers - so audio mixed with computers

http://www.team-bhp.com/forum/1429799-post166.html

http://www.team-bhp.com/forum/1429908-post167.html

and a link to my home theatre setup so you can see that audio is something that i dont only reserve for a car and its a huge part of my life

http://www.team-bhp.com/forum/gadget...tre-setup.html (My home theatre setup)

okay - enough about my stuff before it gets too boring

back to being closer on topic about using the tennis ball remember that you can eventually pull the yellow/green cover off the rubber and then fibreglass the end result so that it becomes a more permanent mount but obviously this is after you get it properly positioned and mounted etc
naughty001 is offline   Reply With Quote
Old 30th December 2009, 10:32   #30
BHPian
 
Gill's Avatar
 
Join Date: Aug 2007
Location: Mohali
Posts: 699
Thanked: 12 Times
Default

I tried the tennis ball pod last night,But the big problem is-Cut the ball properly in two parts, the edges are not as they should be.So will be buying some more balls today to get it done.
OR else Will head to market and search for some 1-2" arclyic balls,Or will head to Carpenter(Wooden Pods,Easier to fabricate and no tensio of FG)
Gill is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tweeter Placement In a 800 jatinpatel In-Car Entertainment 2 27th July 2010 21:32
Best Tweeter placement for Santro Xing greenh0rn In-Car Entertainment 17 26th May 2009 23:04
JBL 607c my-T1 tweeter VS infinity tweeter vkhandelwal In-Car Entertainment 15 31st October 2007 16:31
Apple to make i-pod cellphones rsjaurr Gadgets, Computers & Software 1 14th May 2006 13:32
anbdy using 30Gb Video i Pod ?? a4_attitude Gadgets, Computers & Software 2 1st April 2006 12:23


All times are GMT +5.5. The time now is 10:10.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks