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


Closed Thread
 
Thread Tools Search this Thread
Old 24th February 2009, 12:38   #46
Senior - BHPian
 
Invinsible's Avatar
 
Join Date: Nov 2006
Location: Bombay
Posts: 1,257
Thanked: 60 Times
Default

Quote:
Originally Posted by karankapoor View Post
but most of the amps are overrated and underrated,aren't they.

and this dosen't mean that if they are rated as 900 x 1 they will give 1200 or will give 500rms

how one can calculate the power,when you buy some product first thing you see is the specs & features of the product.
No one is saying that if they are 900x1 they would give 500rms. It's just that the company says 900 but it would give the power between 700 - 800Rms roughly under continous use. Where some are underrated when they 900rms they landup delivering somewhere around the same or 10-15% higher also depends on electricals.

Incase of the kenwoodKAC-9104D it is highly overrated amp. Delivering just around 650RMS of their claimed 900 at 2ohms.
Here's a detailed tech info on it. Please have a read.

Kenwood KAC-9104D - Car Audio & Electronics

Last edited by Invinsible : 24th February 2009 at 12:41.
Invinsible is offline  
Old 24th February 2009, 12:56   #47
Senior - BHPian
 
abhibh's Avatar
 
Join Date: Sep 2005
Location: Back in the HOOD near you!
Posts: 2,767
Thanked: 33 Times
Default

Guys on Test bench most of the amps will fail to produce the amount of power they specify.

And talking about caraudiomag they are inclined towards US products.
abhibh is offline  
Old 24th February 2009, 13:06   #48
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 22,508
Thanked: 3,883 Times
Default

Quote:
Originally Posted by abhibh View Post
Guys on Test bench most of the amps will fail to produce the amount of power they specify.

And talking about caraudiomag they are inclined towards US products.
on the contrary...on a test bench, under the conditions specificed by the manufcturer most amps will outperform their published specs. It is in the real world (less than 14.4V DC, full frequency range, reactive speaker loads, etc..) that most amps fail to live up to their published specs.
navin is online now  
Old 24th February 2009, 13:07   #49
Senior - BHPian
 
panky12345's Avatar
 
Join Date: Mar 2006
Location: New Delhi
Posts: 2,652
Thanked: 126 Times
Default

Quote:
Originally Posted by abhibh View Post
Guys on Test bench most of the amps will fail to produce the amount of power they specify.
I disgaree completely! I've seen couple of bench tests in the US.. and sadly, near 95% of the amps like MTX (old school), JL, Alpine put up more than the specified RMS ratings.

Edit: Just saw Navin's reply.. complete agree here!
panky12345 is offline  
Old 24th February 2009, 13:08   #50
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Quote:
Originally Posted by karankapoor View Post
but most of the amps are overrated and underrated,aren't they.

how one can calculate the power,when you buy some product first thing you see is the specs & features of the product.
Good reputable brand which make amp can be considered as underrated but normal mainstream amp are always overrated.

For calculating the power capability I would simply checkout the fuse rating on the amp or if not on board would check the manual of the same. And would reverse calculate the same. Like if a company says a amp is 1200 x 1 at less than 1 % THD at 14.4 volts. Then there are two variable here also. First at 1% THD the amp is overrated, a good amp is always rated at .1 % THD so in this case the output would have to be less if you need cleaner sound. Now comes the voltage this is the major factor which make the HYPE. Firstly there will never be 14.4 volts in your car the real fiqure will be approx 13 volts. So again the output will be lowered.

Now comes the value of the fuses on the amp. In the above example the fuses on board are 120 amps. So if we reverse calculate it would be like the following...

120 amps so at 13 volts it would consume (120 x 13 = 1560 watts) since the above amp is a AB class it would be 50 % efficient then the real watts it will be giving will be 780 watts.

( Note :- this is the continuous load if we play a sine wave. In music the load will not be continuous.)

So do check all the specs before buying.

Last edited by low_bass_makker : 24th February 2009 at 13:10.
low_bass_makker is offline  
Old 24th February 2009, 14:02   #51
Senior - BHPian
 
abhinav.gupta88's Avatar
 
Join Date: Sep 2007
Location: Delhi , India
Posts: 4,087
Thanked: 308 Times
Default

I'll leave that part for you.
What would a JBL amp (14001).
1200 watt at 4 ohms at 0.04%. give out effectively?
abhinav.gupta88 is offline  
Old 24th February 2009, 14:26   #52
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Quote:
Originally Posted by abhinav.gupta88 View Post
I'll leave that part for you.
What would a JBL amp (14001).
1200 watt at 4 ohms at 0.04%. give out effectively?
Abhinav your amp has 40 amps x 4 fuses on board it means 160 amps...if we reverse calculate it would be 160 amps x 13 volts = 2080 watts. Since yours is a D-Class I would take 75-80 % efficiency so it would be....approx 1560 watts which is quite accurate as mentioned by the manufacturer.
low_bass_makker is offline  
Old 24th February 2009, 15:00   #53
Senior - BHPian
 
abhibh's Avatar
 
Join Date: Sep 2005
Location: Back in the HOOD near you!
Posts: 2,767
Thanked: 33 Times
Default

Quote:
Originally Posted by abhibh View Post
Guys on Test bench most of the amps will fail to produce the amount of power they specify.

And talking about caraudiomag they are inclined towards US products.
Quote:
Originally Posted by panky12345 View Post
I disgaree completely! I've seen couple of bench tests in the US.. and sadly, near 95% of the amps like MTX (old school), JL, Alpine put up more than the specified RMS ratings.

Edit: Just saw Navin's reply.. complete agree here!
Arey even i disagree with my above statement. I did a typo there, forgot to add NOT
abhibh is offline  
Old 24th February 2009, 15:05   #54
Senior - BHPian
 
abhinav.gupta88's Avatar
 
Join Date: Sep 2007
Location: Delhi , India
Posts: 4,087
Thanked: 308 Times
Default

Quote:
Originally Posted by low_bass_makker View Post
Abhinav your amp has 40 amps x 4 fuses on board it means 160 amps...if we reverse calculate it would be 160 amps x 13 volts = 2080 watts. Since yours is a D-Class I would take 75-80 % efficiency so it would be....approx 1560 watts which is quite accurate as mentioned by the manufacturer.
But that is at 2 ohms
What about at 4 ohms.
abhinav.gupta88 is offline  
Old 24th February 2009, 15:27   #55
Team-BHP Support
 
navin's Avatar
 
Join Date: Mar 2004
Location: mumbai
Posts: 22,508
Thanked: 3,883 Times
Default

Quote:
Originally Posted by low_bass_makker View Post
So do check all the specs before buying.
the spec should read as follows:

Power at 12V:
XX watts 20Hz to 20kHz, all channels driven @ 4ohms, THD at rated power < 0.1%, IM at rated power < 0.05%.

even then other factors like the input level at which the amp overloads, the damping factor, and even the weight of the amp can help establish the amp's build quality.
navin is online now  
Old 24th February 2009, 16:06   #56
Senior - BHPian
 
karankapoor's Avatar
 
Join Date: Apr 2008
Location: in the car!!!
Posts: 1,679
Thanked: 2 Times
Default

i think this is more easier way to check how efficient a amp is
as lbm said the total of fuse say 120 amp multiply it by 6 for class AB and by 10 for class D you will get your ans.

Last edited by karankapoor : 24th February 2009 at 16:13.
karankapoor is offline  
Old 24th February 2009, 17:03   #57
Senior - BHPian
 
Join Date: Mar 2006
Location: Faridabad
Posts: 6,814
Thanked: 294 Times
Default

Quote:
Originally Posted by navin View Post
the spec should read as follows:

Power at 12V:
XX watts 20Hz to 20kHz, all channels driven @ 4ohms, THD at rated power < 0.1%, IM at rated power < 0.05%.

even then other factors like the input level at which the amp overloads, the damping factor, and even the weight of the amp can help establish the amp's build quality.
Very true Navin Ji very few mention all this. And some good amp manufacture also mention the Temperature at which they are measured.

Quote:
Originally Posted by karankapoor View Post
i think this is more easier way to check how efficient a amp is
as lbm said the total of fuse say 120 amp multiply it by 6 for class AB and by 10 for class D you will get your ans.
I would take 6.5 for the AB class and 9.5 for the D Class.

Quote:
Originally Posted by abhinav.gupta88 View Post
But that is at 2 ohms
What about at 4 ohms.
By the fuse method we can calculate the max output of the amp at which it can play.

Last edited by low_bass_makker : 24th February 2009 at 17:08.
low_bass_makker is offline  
Old 24th February 2009, 18:50   #58
Senior - BHPian
 
panky12345's Avatar
 
Join Date: Mar 2006
Location: New Delhi
Posts: 2,652
Thanked: 126 Times
Default

That means my JBL 1201.1 can churn out 1404 W RMS (at the peak in continous play) as against 1114W RMS? Then what is meant by Dynamic Power?

Interesting observation though.. Lets compare some more..
panky12345 is offline  
Old 24th February 2009, 20:24   #59
Senior - BHPian
 
abhinav.gupta88's Avatar
 
Join Date: Sep 2007
Location: Delhi , India
Posts: 4,087
Thanked: 308 Times
Default

Quote:
Originally Posted by low_bass_makker View Post
By the fuse method we can calculate the max output of the amp at which it can play.
Is there a method by which i can find out how much does it churn out at 4 ohms when the one at 2 ohms churns out 1500.
Quote:
Originally Posted by panky12345 View Post
That means my JBL 1201.1 can churn out 1404 W RMS (at the peak in continous play) as against 1114W RMS? Then what is meant by Dynamic Power?

Interesting observation though.. Lets compare some more..
What is the fuse rating on your 1201.1?
abhinav.gupta88 is offline  
Old 25th February 2009, 02:03   #60
Senior - BHPian
 
abhinav.gupta88's Avatar
 
Join Date: Sep 2007
Location: Delhi , India
Posts: 4,087
Thanked: 308 Times
Default

Also i dont think it should make a difference but , is it better to get 2 amps of 1200 watt rms powering the subs at 4 ohm or 1 amp of 2400-2500w rms powering the sub at 2 ohm?

Last edited by abhinav.gupta88 : 25th February 2009 at 02:13.
abhinav.gupta88 is offline  
Closed Thread


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Difference between a Monobloc and 2 Channel Amplifier for the Subwoofer? frankmehta In-Car Entertainment 52 21st November 2011 17:23
Advice needed for performance upgrade for the 1.3 Ikon Dragonov Modifications & Accessories 5 4th June 2006 12:43
Budget Car Audio Advice Needed Guys thief In-Car Entertainment 22 26th January 2006 14:59
advice needed: car audio in hyundai accent amit_baghe In-Car Entertainment 273 25th December 2005 00:04
Repainting & "Sumo to Sumo victa" conversion. Advice needed. nitrous Modifications & Accessories 0 21st November 2005 12:57


All times are GMT +5.5. The time now is 16:06.

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