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Old 4th November 2005, 11:38   #136
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Originally Posted by RobertClive
I read quite few installations (not in this forum) where people use both the LPF in the HU and LPF in the amp. Accordingly, it improves the SQ since slope of subwoofer cutoff frequency is very steep. Have any of you guys tried this?

Will this lead to any kind of phase shift. To my knowledge, even -18db/octave will lead to a phase shift that cannot be compensated at all. Either -12db/octave or -24db/octave would be a good choice since it would be a multiple of 180 degree phase shift.

What say gurus?
When you use the crossovers twice on the same frequency (HPF or LPF) the slope gets steeper...for example if you are using 80Hz LPF, 12dB slope on the head unit and 80Hz LPF 12 dB slope on the amplifier. it will result in summing and it will act as a 80Hz crossover with 24dB slope.

A lot of good mono amps has 24dB LPF for the subwoofer. Using the steeper slope in subwoofers results in good SQ for many reasons...the subwoofer gets tighter frequency window with less roll off hence cleans the midrange. Also with steep slopes the bass becomes tight and more defined. Lot of people in who compete in SQ competitions use even steeper slope like 36dB/octave and 48dB/octave for subs using professional processors.

Phase shift occurs at every 6dB of slope change and phase gets inverted at every 12dB. Very few amps (like Audison VRx) has variable phase control. So my suggestion to you is stick to multiples of 12dB which can be taken care by 0-180 Deg phase inverting switch common on amps and HU's.
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Old 4th November 2005, 12:26   #137
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phase response is a long subject and I would reserve that for another fourm. As it is the other mods are wondering who the ICE thread is the fastest growig thread (in replies) on a Car forum. I dont want them to get too excited about this. :-)

suffice to say that if you really want to study phase response it must be studied in the car. The time / distance difference the various drivers have to the listeners ear will also affect the phase response as heard by the listener.

Now before you guys go out and get crazy wtih the multi order polynominals that would be required to solve this mathematically I would ensure you that it is not all that bad. why?

1. the ear is really sensitive over about 5 octaves (about 200-5000) and it's sensitivity to errors outside this range falls pretty rapidly.

2. the car enviroment is both very dead (seats) and very live (windsceens) and that together with road noise compunds the effects to the point to where trying to correct for all phase/frequency/transient response errors is damn near impossible. A waterfall plot of a speaker in a car is ugh!
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Old 4th November 2005, 12:39   #138
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Navin...play with crossover frequencies, slopes & phase. After you get good integration between the subs and speakers. Delay the subwoofer until it comes on your dashboard (for upfront bass and integration) and you are done.

Also very few HU's have good Time Alignment...lot of them affects the sound quality. So its like choosing the best sound out of some compromises
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Old 23rd March 2006, 11:29   #139
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Smile What is missing?

Hi all audio gurus,

This is my first post!

For the last couple of weeks i have been reading through quite a few of the threads and found the information useful.

I wanted some advice for my current audio setup:

Car: Swift Vxi
HU: Pioneer 5750
Front speakers: 6.5" pioneer TS 1681 (a wooden spacer was added to accommodate these speakers in the front doors)
Rear speakers: 6.5" pioneer TS 1681 (4-ways)
Note: On all four doors

Now my questions are:
1. What are your comments on the pioneer TS 2150 (its a discontinued model, but it has excellent audio quality, I heard it on a friends car, it was connected to a pioneer cassette HU, he said that you don’t need anything after you connect these, no amp, no tweeters as it has all built in). These cost around 5.5-6k
Link: http://www.pioneer.com.sg/storefront...&CatId=2,27,44
2. How would my audio setup be if I connect these (pioneer TS 2150) in the rear onto the parcel tray and power it and the rear speakers on the doors through an amp? And let the front speakers be powered by the HU.
3. How would it be if I remove the front 2 speakers and connect the JBL 606's instead and the back speakers will remain the same (TS1681s), all powered by the HU, what would be difference in sound? I don’t like to much of "chann chann" sound.
4. How would it be if I just connect a JBL 1200T to a 502 Sony amp to my existing setup, will it enhance the audio experience?
5. I get this vibrating noise from my speaker present on the right passenger door when I crank up the volume, how can I get rid of this?
6. What can I do to the existing setup to get more bass and I don’t know, I feel something else is missing cannot exactly pin point it though!
And the other thing is I don’t want to loose my boot, I would like to have a removable tray setup.
Waiting for your response, guys.

Thank you

Last edited by varun_suri : 23rd March 2006 at 11:30.
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Old 16th February 2008, 12:12   #140
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Default My swift audio system setup

Hi guys, its more about 2 years since I started this thread and left without any conclusion. Well, I spent so much time on this forum that I almost got fired from my job. Made a resolution that would not come back for quite some time.

My swift setup: (note: prices except sub is from 2005)

HU: Pioneer 5850 (3 preamp out) (Rs 7000)
Amp: Pioneer GM-515 (5 channel) (Rs 17000)
Front components: Hertz energy series 6" (Rs 14500)
Sub: 2 Rockford Fosgate 8" connected in parallel ($60 each)
damping: complete front door

Here are some finding of mine and hope this might be useful for someone.

1. Performance of components

Hertz energy series has a silk dome tweeter and is very smooth; very much to my liking. But as with most silk dome, imaging is not very great. Part of the reason might be the design of swift. The dash in swift is so small that you can touch the front wind screen without any effort. This means the tweeters will be much closer to the driver in swift and hence imaging is lost a bit. The imaging is very good if I listen from rear seat. The mid bass produced is very good. I really like these and definitely recommend to any one who has budget. This is the best sounding components I have experienced.

2. Pioneer amp

I guess I was lucky to get a 5 channel pioneer amp. Its is very rare and met by price budget at that time. The amp as such has decent quality. I don't use it to its maximum (amp rating: 65W x 4 + 200W at 4ohms and 56W x 4 + 300W at 2 ohms (sub)). No complaints whats so ever.

3. 8" sub under front seat

Initially, I was using single 8" Image Dynamics subwoofer (ID8D4 V3) under co-passenger seat. I tried to make the sub box completely air tight but inspite of my best efforts, I could not. I guess the Xmax of 15mm for a box volume of .2 cubic ft. cannot have a air tight box. It is bound to leak one way or other since air inside will be compressed to a greater extent. I did finally achieved air tight enclosure by using silicon sealant to seal the subwoofer with the box instead of supplied gasket. While the subwoofer is very good in terms of SQ, it floors very easily giving that metallic sound. This seams a common problem with the 8". Also for keeping the sub under the co-passenger seat, I had to raise the seat platform by an inch.

After doing a bit of research, I found Rockford fosgate punch stage 2 8" sub that meets my requirement:
Mounting depth : less than 4", Sealed enclosure: .15 - .35 cubic ft., X max - 8mm, Vas - 10.5 ltr.
But the resonant frequency was very high - 40Hz and this means in a sealed enclosure, -3db rolloff would happen at 67Hz. Pretty high for a sub but I had no choice. Couldn't manage more than .22 cubic ft.

After installing and bit of tweaking, now I have a very good setup. I have two subs under my front seats and hence have upfront bass. Couple of things that noted while installing the subs are:

a. covering the sub with good quality carpet has definite advantages. It takes out the sound produced by the box material. I have two layers of flooring carpet (1/4 inch total thickness) and this reduced some unwanted sound colouring. This is important if the subs are very near to the listening position. Using MDF instead of particle board also helped.

b. When the sub is placed under the seat, every little vibration is transmitted to the listener which may be undesirable for some (it sure was undesirable for me). Plus, the space under the seat can create some kind of enclosure effect resulting in boomy bass. For getting tighter bass, I made a setup as shown below.

c. 8" subs under front seats can give you upfront bass and save boot space ( which is premium in smaller hatchbacks) and can be driven by a smaller amp. I had a setup for my cousin's estilo: DLS 6" comp (Rs 7000), Pioneer HU (Rs 5000), JBL 4 channel amp (Rs 5000) - 2 for front and bridged 150W for sub, RF 8" sub ($60) extras came upto Rs. 22000. Sounds good for the price.

d. 8" subs cannot produce SPL when compared to 10". But if placed properly near the listening position, can give you good SQ especially in pleasant volumes ( relative term but lets say the volume you would prefer if you listen to country rock)

4. Sound damping

Sound damping products like dynamat is an absolute must for swift. Too much rattling at higher volumes.
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Old 19th February 2008, 00:06   #141
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Originally Posted by RobertClive View Post
Hi guys, its more about 2 years since I started this thread and left without any conclusion. Well, I spent so much time on this forum that I almost got fired from my job. Made a resolution that would not come back for quite some time.
Hi Arun, its great to have you here. Welcome back.
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Old 19th February 2008, 11:06   #142
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Any pics of the above install Arun.
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