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


Reply
 
Thread Tools Search this Thread
Old 7th June 2012, 12:16   #286
Distinguished - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,068
Thanked: 2,866 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
... I have been told to feed them higher than rated power and that's what I am doing. I hope I am not wrong. ...
Are you aware how much power is going to your speakers in normal listening conditions? Definitely not "higher than rated power". There is no straightforward calculation that tells you how powerful should the amp be based on your loudness requirements. But, if your speakers are rated 100W and the amp is rated 150, there is a high chance that the speakers will give up their ghost when you really crank up the volume - since you won't be sitting and doing voltage and current calculations to figure out which loudness level is safe.

If you want an SPL system - out and out deafening loud music heard a couple of blocks away - you should get a system that caters to that requirement: higher power speakers and amps. Otherwise, for normal listening, one doesn't have to resort to bridging the output of an amp, even if it is to satisfy those times when you really want to crank it up.
DerAlte is offline   (1) Thanks Reply With Quote
Old 7th June 2012, 12:53   #287
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by DerAlte View Post
Are you aware how much power is going to your speakers in normal listening conditions? Definitely not "higher than rated power". There is no straightforward calculation that tells you how powerful should the amp be based on your loudness requirements. But, if your speakers are rated 100W and the amp is rated 150, there is a high chance that the speakers will give up their ghost when you really crank up the volume - since you won't be sitting and doing voltage and current calculations to figure out which loudness level is safe.

If you want an SPL system - out and out deafening loud music heard a couple of blocks away - you should get a system that caters to that requirement: higher power speakers and amps. Otherwise, for normal listening, one doesn't have to resort to bridging the output of an amp, even if it is to satisfy those times when you really want to crank it up.
I have a problem finding mission scheduled for this Saturday.

During the process, I shall change the wiring to single channel mode on the amp.

But, it would reduce the power being fed to the speakers to 60W from the current 150W being fed. Won't this short powering take the juice out from the music?


P.S. I definitely do not want any spl system. I want rich encapsulating music in the car.
deepfusion is offline   Reply With Quote
Old 7th June 2012, 13:19   #288
Distinguished - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,068
Thanked: 2,866 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
... it would reduce the power being fed to the speakers to 60W from the current 150W being fed. Won't this short powering take the juice out from the music?

P.S. I definitely do not want any spl system. I want rich encapsulating music in the car.
If you were to really measure the power being fed into your speakers with the volume control at ~50% (usually decently loud), it would be somewhere between 5 and 30W rms, depending on what kind of music passage is playing. HU internal amps croak at high volumes because, with 14W rms rating, they do not have sufficient margin to pump into speakers when going loud. One *never* sees rated power of the amp going into the speaker normally.

Only when coincidentally there are peaks of loudness for *all* instruments in the music passage, like a crescendo in an orchestral composition, that the power going through the speaker exceeds 30W. At a higher volume setting for normal listening (not SPL), this might go up to 60W or slightly higher. In your case, both the amp and the speaker are able to handle the power demand safely - a 60W amp can dump even 100W for a short time.
DerAlte is offline   Reply With Quote
Old 7th June 2012, 13:58   #289
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by DerAlte View Post
If you were to really measure the power being fed into your speakers with the volume control at ~50% (usually decently loud), it would be somewhere between 5 and 30W rms, depending on what kind of music passage is playing. HU internal amps croak at high volumes because, with 14W rms rating, they do not have sufficient margin to pump into speakers when going loud. One *never* sees rated power of the amp going into the speaker normally.

Only when coincidentally there are peaks of loudness for *all* instruments in the music passage, like a crescendo in an orchestral composition, that the power going through the speaker exceeds 30W. At a higher volume setting for normal listening (not SPL), this might go up to 60W or slightly higher. In your case, both the amp and the speaker are able to handle the power demand safely - a 60W amp can dump even 100W for a short time.
This would imply that whatever power I am feeding to the speakers is in fact killing the speakers gradually.

Another thought, what would happen if the gains at the amplifier are reduced substantially, without changing the wiring pattern.
deepfusion is offline   Reply With Quote
Old 7th June 2012, 14:25   #290
Distinguished - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,068
Thanked: 2,866 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
This would imply that whatever power I am feeding to the speakers is in fact killing the speakers gradually. ...
No, that would be a very radical thought. In reality, current flowing through the speaker heats the coil (with whatever power is not converted to cone motion), but the coil gradually loses heat. There is a balance achieved at a certain temperature in normal playing. It is only when there is more heating than cooling that the bad effects manifest. (Now, please don't start thinking of a cooling system for the coil )

Quote:
Originally Posted by deepfusion View Post
... what would happen if the gains at the amplifier are reduced substantially ...
Gain has little to do with it. Yes, lesser gain = lesser chances of a problem. However, if the signal from HU is large enough, it will still cause a power overshoot. Gain does not limit high signal amplitude, it only serves to amplify low amplitude signals to an acceptable level.
DerAlte is offline   (1) Thanks Reply With Quote
Old 7th June 2012, 14:30   #291
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by DerAlte View Post
No, that would be a very radical thought. In reality, current flowing through the speaker heats the coil (with whatever power is not converted to cone motion), but the coil gradually loses heat. There is a balance achieved at a certain temperature in normal playing. It is only when there is more heating than cooling that the bad effects manifest. (Now, please don't start thinking of a cooling system for the coil )

Gain has little to do with it. Yes, lesser gain = lesser chances of a problem. However, if the signal from HU is large enough, it will still cause a power overshoot. Gain does not limit high signal amplitude, it only serves to amplify low amplitude signals to an acceptable level.
Sir, please tell me in an easy to understand manner. I study in nursery class of ICE school.
deepfusion is offline   Reply With Quote
Old 7th June 2012, 16:36   #292
Distinguished - BHPian
 
DerAlte's Avatar
 
Join Date: Mar 2007
Location: Bangalore
Posts: 8,068
Thanked: 2,866 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
Sir, please tell me in an easy to understand manner. I study in nursery class of ICE school.


1. No, speakers are not 'gradually killed' when used normally

2. No, reducing gain will not limit the signal coming from the HU to amp. There would still be a possibility that HU volume is near max and you play real loud jhin-chak tabad-tod murde-ko-jaga-de music, and the resulting power overload blows the speaker
DerAlte is offline   Reply With Quote
Old 7th June 2012, 17:00   #293
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by DerAlte View Post


1. No, speakers are not 'gradually killed' when used normally

2. No, reducing gain will not limit the signal coming from the HU to amp. There would still be a possibility that HU volume is near max and you play real loud jhin-chak tabad-tod murde-ko-jaga-de music, and the resulting power overload blows the speaker
Okay. That means the speakers would have to be powered at around 100W. Lower would be better then.

Got it. I shall change the settings ASAP.
deepfusion is offline   Reply With Quote
Old 8th June 2012, 17:20   #294
Distinguished - BHPian
 
Sam Kapasi's Avatar
 
Join Date: Jul 2005
Location: Mumbai (but wat
Posts: 6,985
Thanked: 1,366 Times
Default Re: Queries in 'Ask the gurus' section

Gain - is NOT a volume control - and there lies the greatest mistake of uninformed installers. Especially in a country where quantity wins over quality.

Every head unit has a Vpp - a peak to peak voltage when the volume is raised to a fairly high level. Standard is around 2Volts but head units for the car can go up to 4 and 6 volts too.

It is because of this non standardization of the output volume that the amplifier has an adjustable gain. It needs to match the output offered by the head unit.

If the car system gets too loud before you can turn up to halfway (on the volume knob) - your gain is too high.

Disadvantages?

Well many.
  • An amplifier with high gain will also amplify all the rubbish it isn't supposed to amplify. Clicks, pops, whines and more.
  • If you use "loudness" - I know most people do. Loudness is designed to enhance the bass (and/or treble) when playing at a low volume. This loudness equalization is supposed to taper off as you go higher on the volume scale.
    However if your amplifier is set to unnecessary high gains, the head unit believes it is playing softly, but the amplifier is turning it all the way up to loud, hence an unnatural amplification of the lows and highs.
  • As you turn the head unit up, too much gain tends to clip off important parts of the sound signal, resulting in a "awaaz phat raha hai" kind of sound.
A simple way to set gain (even if this is not technically perfect) is to turn the amplifier gain ALL the way down, turn the voume on your head unit at about 80% of all the way up (example:if your volume goes up to 50, turn it up to 40) and then turn the amplifier gain up slowly until the sound is loud and clear and does not sound like it is distorting.

Quote:
Originally Posted by DerAlte View Post

jhin-chak tabad-tod murde-ko-jaga-de
Sam Kapasi is offline   (1) Thanks Reply With Quote
Old 9th June 2012, 12:23   #295
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by Sam Kapasi View Post
Gain - is NOT a volume control - and there lies the greatest mistake of uninformed installers. Especially in a country where quantity wins over quality.

Every head unit has a Vpp - a peak to peak voltage when the volume is raised to a fairly high level. Standard is around 2Volts but head units for the car can go up to 4 and 6 volts too.

It is because of this non standardization of the output volume that the amplifier has an adjustable gain. It needs to match the output offered by the head unit.

If the car system gets too loud before you can turn up to halfway (on the volume knob) - your gain is too high.

Disadvantages?

Well many.
  • An amplifier with high gain will also amplify all the rubbish it isn't supposed to amplify. Clicks, pops, whines and more.
  • If you use "loudness" - I know most people do. Loudness is designed to enhance the bass (and/or treble) when playing at a low volume. This loudness equalization is supposed to taper off as you go higher on the volume scale.
    However if your amplifier is set to unnecessary high gains, the head unit believes it is playing softly, but the amplifier is turning it all the way up to loud, hence an unnatural amplification of the lows and highs.
  • As you turn the head unit up, too much gain tends to clip off important parts of the sound signal, resulting in a "awaaz phat raha hai" kind of sound.
A simple way to set gain (even if this is not technically perfect) is to turn the amplifier gain ALL the way down, turn the voume on your head unit at about 80% of all the way up (example:if your volume goes up to 50, turn it up to 40) and then turn the amplifier gain up slowly until the sound is loud and clear and does not sound like it is distorting.



The problem with my system is, there is this krr sound accompanying the audio at some frequencies, at low volume. When volume is increased, the krrr disappears, but I can sense it happening then too. But its too muddled to be clearly heard.

The gains on the Amps match the 4V output generated by the HU.

The loudness is set to ZERO on the HU. Should I set it to low/med/high? Please guide.

BTW, I tried to DIY the gains settings today morning.

I lowered the gains as an experiment, before I tried shifting the speakers to single channel mode from bridged channel mode.

The result:

The speakers are now sounding sweet.

I will be giving an audition to the system tomorrow during the long drive and update the results here.

But the sub's sound is worrying me now. I have tried lowering the gain, but the problem is, when the bass boost on the amp is increased to 12dB, the sub also starts giving out an additional sound. I have lowered the bass boost to about 6dB. It seems okay for now.

There were some loose connections left by the installer. Those were taken care.
deepfusion is offline   Reply With Quote
Old 10th July 2012, 11:25   #296
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 21,963
Thanked: 3,504 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by DerAlte View Post
(Now, please don't start thinking of a cooling system for the coil ).
Acually today most woofers have vented pole pieces allowing for the movement of air around the coil even when the coil is in motion. It helps improve the duty cycle of the voice coil little (10-15%). That "little" is often all you need to prevent failure. Also many subwoofers are now wound on aluminum formers which helps dissapate the heat too. Anodised aluminum is a superb radiator of heat while not permitting the flow of electricity (aka short circuit).

Remember a hot coil's impedance is slightly more than a cold coil. Hence a hot coil will draw less current from the amp. So unless you keep turning the amp's volume up if your speaker can survive the first 30 minutes it should survive the next 300 minutes too.

Quote:
Originally Posted by deepfusion View Post
The problem with my system is, there is this krr sound accompanying the audio at some frequencies,

BTW, I tried to DIY the gains settings today morning.
The speakers are now sounding sweet.

But the sub's sound is worrying me now. I have tried lowering the gain, but the problem is, when the bass boost on the amp is increased to 12dB, the sub also starts giving out an additional sound. I have lowered the bass boost to about 6dB. It seems okay for now.
Your subwoofer's excursion limits were being exceeded. Be careful doing so can damage your subwoofer irrepairably.

Did the "krrrr" noise go away when you turned the gains down?
navin is offline   (1) Thanks Reply With Quote
Old 10th July 2012, 12:09   #297
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by navin View Post
Did the "krrrr" noise go away when you turned the gains down?
No Sir. The sound persists. I have tuned the HU and lowered the 100 Hz frequency. The problem seems hidden now, but the sound is a muffled one at/around this 100 Hz frequency.

I doubt that the door needs more damping on the outer wall, and the ring to which the speakers have been attached also to be damped.

May be, my reading is alright.

What do you suggest?


Quote:
Originally Posted by navin View Post
Your subwoofer's excursion limits were being exceeded. Be careful doing so can damage your subwoofer irrepairably.
So, is the setting I have made alright, or do I need to do something else? I have already lowered the subwoofer setting on the HU to -10 from the given setting of -24 to +6

Last edited by deepfusion : 10th July 2012 at 12:12.
deepfusion is offline   Reply With Quote
Old 10th July 2012, 16:36   #298
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 21,963
Thanked: 3,504 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
No Sir. The sound persists. I have tuned the HU and lowered the 100 Hz frequency. The problem seems hidden now, but the sound is a muffled one at/around this 100 Hz frequency.

So, is the setting I have made alright, or do I need to do something else? I have already lowered the subwoofer setting on the HU to -10 from the given setting of -24 to +6
I am a bit confused. Is the sound is coming from the midbass which has been HPF at 100hz (I assume 12db/oct)? or is the sound coming from the subwoofer which has been LPF at 100hz?
navin is offline   Reply With Quote
Old 10th July 2012, 16:54   #299
BHPian
 
Join Date: Dec 2009
Location: Gurgaon,N.Delhi
Posts: 452
Thanked: 116 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by navin View Post
I am a bit confused. Is the sound is coming from the midbass which has been HPF at 100hz (I assume 12db/oct)? or is the sound coming from the subwoofer which has been LPF at 100hz?
Sir, the krrr sound from mid bass is audible at 100Hz setting on the Graphic Eq. on the HU. HPF and LPF on the HU are set at 80Hz.
deepfusion is offline   Reply With Quote
Old 11th July 2012, 13:50   #300
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 21,963
Thanked: 3,504 Times
Default Re: Queries in 'Ask the gurus' section

Quote:
Originally Posted by deepfusion View Post
Sir, the krrr sound from mid bass is audible at 100Hz setting on the Graphic Eq. on the HU. HPF and LPF on the HU are set at 80Hz.
So this is what I understand
a. The midbass is HPFed at 80Hz
b. You hear the 'krr' at 100hz from the midbass

1. turn the graphic eq to flat.
2. feel the door panel near the midbass or midbass basket/grill and turn up the volume till you begin to hear the 'krr' sound. repeat with various music and report if the sound is more noticeable with different artists.
3. if you can increase the slope of the HPF filter to 18db o 24db.

Does the 'krrr' sound have any harmonics or is it only at 100hz?
navin 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
Automobile Insurance Queries? Ask me rjvora_2000 Indian Car Loans & Insurance 3837 25th May 2017 12:44
Google SMS - An end to Ask me service ! Sahil Shifting gears 12 30th January 2008 00:05
The Newbie Thread: Things you were scared to ask vidvai Technical Stuff 30 17th August 2007 17:30
P-150 classic for sale .What can i ask for jango Motorbikes 1 31st March 2006 12:51


All times are GMT +5.5. The time now is 01:17.

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