[navin]

Originally Posted by ::CMS::

But all these are not applicable for the frequencies produced by a subwoofer which have wavelengths more than a car.

Why not? Care to elaborate?

The way I see it is that a subwoofer-box having an impednace peak at 30hz (quite normal for a car subwoofer) will benefit from damping as would the absorbing of part of a woofer's back wave in a box.

[::CMS::]

As far as I understand, using a small enclosure than the designed size (say a Q of .7 / .8), will increase the Q significantly (main cause for mid bass bumps \ muddy \ booming). Adding a polyfill will help in reducing the Q by keeping the F3 along with the impedance peak (enclosure only,not driver peak), but at the cost of reduced efficiency leading to more powered amps and chances of driver bottoming out (due to over filling). I am not against the filling, but not for the purpose of reducing \ removing the standing waves of a sub, as per my understanding it will not have any effect, its more effective for midbass speakers. If we are able to do that, large corner traps in HT rooms are not required.

[navin]

Originally Posted by ::CMS::

As far as I understand, using a small enclosure than the designed size (say a Q of .7 / .8), will increase the Q significantly (main cause for mid bass bumps \ muddy \ booming). Adding a polyfill will help in reducing the Q by keeping the F3 along with the impedance peak (enclosure only,not driver peak), but at the cost of reduced efficiency leading to more powered amps and chances of driver bottoming out (due to over filling). I am not against the filling, but not for the purpose of reducing \ removing the standing waves of a sub, as per my understanding it will not have any effect, its more effective for midbass speakers. If we are able to do that, large corner traps in HT rooms are not required.

CMS, I am replying over mobile so please excuse typos.

I am no expert or guru so please forgive any misconceptions I have in my posts.

I agree that most damping materials have a greater effect in the mid-bass than in the low bass. Yes if one over damps a box it will rob a speaker of it's dynamics but we are talking adequate damping not over damping.

a. By adding mass (aka damping material) to a panel we will lower it's Fs. Won't this help?
b. By adding mass to a panel we increase the energy required to excite the panel. Won't this help?
c. By reducing even the mid bass reflected energy from a panel dont you think the cone will operate more truly (reduced Doppler distortion)
d. Qtc of 0.7 may be theoretically "right" but when you factor in room gain (cabin gain) and also linearity of cone movement (given modern suspensions) a Qtc in the range of 0.5-0.6 is often preferred.

By adding damping to a box (let's assume a simple sealed box) you lower the effective Q (Qtc) thereby giving a more linear response. You also lower impedance peaks so the amplifier sees a more linear load. The amplifier hence behaves in a more efficient manner no?

Lastly, I think we were talking of reflected waves not standing waves.

[srishiva]

Audio pioneer Ray Dolby dies
http://www.bbc.co.uk/news/world-us-canada-24075429

[sridhar_blr80]

1. My Car: Fiat Palio 1.6 Sport

2. Mycurrent setup (If any):

HEAD UNIT: Blaupunkt Maui MP 36
• 4-Channel Preamp-Out (3 V)
• Sub-Out: fixed

DOOR SPEAKERS: Thc 132 5 1/2 Inch Blaupunkt Component Speakers.
Max. power 150 watts
Nominal power 50 watts
Nominal impedance 4 ohms

REAR SPEAKERS: JBL GTO937 (6" x 9" 3-Way Loudspeaker)
Power Handling, RMS 100 Watts
Power Handling, Peak 300 Watts
Frequency Response 50Hz-21kHz
Sensitivity 94dB
Impedance 2 Ohms

AMPLIFIER:
Got a 2 channel Blaupunkt GTA 2 Special

SUB-WOOFER:
Blaupunkt 12" GTW 1200 sub-woofer

3. My Budget: INR <10k

4. Do you drive most of the time or is it chauffer driven? Self-driven

5. Your Music preferences (Genres, favorite artists, etc.):POP, Instrumental, Soft Rock, Heavy Metal - when alone !!

Additional Information:

6. Are you ready to sacrifice your boot space/modify door panels? : Already have

HELP WITH,
My CD on the HU stopped working, cleaning disks are not helping, inquired about service, got reply that BP has closed shop in INDIA, better to upgrade HU as they are not sure of spare parts.

Decided to go for a new HU with new features, like BT Streaming, USB/AUX IP, CD (a must pls)

Also was thinking of pumping-up power to front component speakers…

SUGGESTIONS, QUESTION WELCOME PLS,

Thanks
Sri.

[DerAlte]

Originally Posted by sridhar_blr80

... DOOR SPEAKERS: Thc 132 5 1/2 Inch ... REAR SPEAKERS: JBL GTO937 (6" x 9" 3-Way Loudspeaker)
... Got a 2 channel Blaupunkt GTA 2 Special
... Blaupunkt 12" GTW 1200 sub-woofer

3. My Budget: INR <10k
...
Decided to go for a new HU with new features, like BT Streaming, USB/AUX IP, CD (a must pls)

Also was thinking of pumping-up power to front component speakers…
...

You were powering the sub without powering the front components at least all this while?

You should definitely get a 4 channel amp to power the front and rear. Will cost you ~6K plus some for cables etc. Had you bought a 4ch amp when you bought the 2channel for the sub, you would have had a system that at a pinch didn't need additional investment.

Whom did you ask for repairing the Blau HU? If you haven't already, ask Bosch Service. They will tell you which of the old service centers will repair it for you. Spares shouldn't be a problem.

Now, if you want a new HU, your budget is already shot. A decent 1DIN HU from Kenwood, JVC or Pioneer with the features you desire will cost you ~8K. Check their India websites for the MRP - street prices should be at least 15% less.

[sparkguy]

Hi Gurus;

Need urgent help.
Yesterday I was playing my car audio at relatively higher volume and I could witness dimming of headights and roof light. All four guns of central locking also gone bad and according to mechanic it was due to fluctuation.

1) Is playing music at high volume is culprit? or this is just my imagination and I need to look somewhere else for issue
2) If yes what I need to do to avoid this

My current setup is

1) HU----Pioneer DEH 4590 BT
2) Front 4" Kenwood Speakers
3) Rear JBL GTO 949

Untill I get the reply and assurance I am going to keep my HU switched off.

[DerAlte]

Originally Posted by sparkguy

... Yesterday I was playing my car audio at relatively higher volume and I could witness dimming of headights and roof light. All four guns of central locking also gone bad and according to mechanic it was due to fluctuation. ...

Did the car start normally after fitting the system at the installer? Or was there a bit of struggle?

I suspect the installer didn't reconnect the battery properly. They usually disconnect the battery to prevent shorts when they are installing. You can check it yourself and tighten the terminal.

[sparkguy]

Originally Posted by DerAlte

Did the car start normally after fitting the system at the installer? Or was there a bit of struggle?

I suspect the installer didn't reconnect the battery properly. They usually disconnect the battery to prevent shorts when they are installing. You can check it yourself and tighten the terminal.

Yes car was running properly after installation. It ran for a week and then this happened. Anyway I would again check this today, Thanks for this.

So there is no relation between playing music at high volume (rear speakers are 400 watts) and voltage fluctuation. Correct?

[Pheonix]

Originally Posted by sparkguy

Yes car was running properly after installation. It ran for a week and then this happened. Anyway I would again check this today, Thanks for this.

So there is no relation between playing music at high volume (rear speakers are 400 watts) and voltage fluctuation. Correct?

AFAIK High volumes shouldnt cause such things . Apart from the battery issue pointed out by DerAlte , i suspect if anything might have gone wrong with the wiring, as this sounds similar to an old issue with one of my friends where car lost all its power windows feature due to a wiring gone bad during audio installation. Dont know why he had to mess up with those wires for setting up the speakers but luckily he got it sorted out later.

[DerAlte]

Originally Posted by sparkguy

... So there is no relation between playing music at high volume (rear speakers are 400 watts) and voltage fluctuation. Correct?

There is. Ignore the speaker wattage. When you play loud, the current drawn from the system, ultimately battery, is high. This causes the voltage to dip - either if the alternator is not able to supply / regulate, or if there is a large voltage drop near the battery terminal or Accessory fuse.

You must have been playing really loud for this to happen. You must have ignored distortion too?

[archat68]

Originally Posted by sparkguy

Hi Gurus;

Need urgent help.
Yesterday I was playing my car audio at relatively higher volume and I could witness dimming of headights and roof light. All four guns of central locking also gone bad and according to mechanic it was due to fluctuation.

You were playing loud music with your headlights on and engine turned off?? That is a sure way to discharge the battery .

Even if you play at 100% volume your HU is rated 15-18W per channel. That is around 70W total power. Theoretically assuming your engine was turned off the battery voltage should be around 12.2V-13V. That means your audio system was drawing about 6A of current from battery. Assuming your battery is 35AH and was fully charged it is capable of supplying such amount of current for about 6 hours. So should not be an issue for 1 hour or so.

But if it was partially discharged or headlights were turned on at the same time things go worse.

[sparkguy]

Originally Posted by DerAlte

There is. Ignore the speaker wattage. When you play loud, the current drawn from the system, ultimately battery, is high. This causes the voltage to dip - either if the alternator is not able to supply / regulate, or if there is a large voltage drop near the battery terminal or Accessory fuse.

You must have been playing really loud for this to happen. You must have ignored distortion too?

Yes I was playing lound. I was checking the max volume my HU can support . What can I do to prevent such fluctuations in future since I am fond of playing music in high volume? Please help me with this

[sparkguy]

Originally Posted by archat68

You were playing loud music with your headlights on and engine turned off?? That is a sure way to discharge the battery .

I was driving.

Following electricals were on
1) Head lights (80/100 bulbs with relay and ceramic holders)
2) AC
3) Occasional honking
4) Tails lights
5) Music

Do you think I have overloaded the battery? How to avoid this

[archat68]

Originally Posted by sparkguy

I was driving.

Do you think I have overloaded the battery? How to avoid this

I don't think so. When you are driving your alternator is supplying the current NOT your battery provided your alternator is OK.

As suggested by DerAlte check the battery cables and wiring of HU, speaker.