18 watts rms in a head unit - BMW Forum - BimmerWerkz.com
BMW Forum BMW Forum

Auto Insurance

» Featured Product
Wheel & Tire Center

Go Back   BMW Forum - BimmerWerkz.com > General Category > Audio and Electronics
Register Home Forum Active Topics Gallery / Showroom Auto Loans Garage Search Today's Posts Mark Forums Read Auto EscrowInsurance

Audio and Electronics The place to go to discuss sound systems and show off your I.C.E. along with security systems and radar detectors too!

BimmerWerkz.com is the premier BMW Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 08-03-2004, 07:04 PM   #1 (permalink)
2nd Gear Member
 
trinidon2k's Avatar
 
Join Date: Aug 2003
Location: Chicago
Car:
Posts: 371
Photos:
trinidon2k is an unknown quantity at this point
Send a message via AIM to trinidon2k
i'm looking to get the alpine 9830 but the rms is only 18 ...from my knowledge (which is extremely limited) that isnt good....as a matter of fact....most, if not all of the alpine units (on the crutchfield, what fits my car search) under $350 are 18 watt rms....so the why is it looked upon so highly?
trinidon2k is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 08-03-2004, 09:43 PM   #2 (permalink)
n00b
 
Join Date: Jul 2004
Car:
Posts: 30
Photos:
trippinbillies40 is an unknown quantity at this point
the 9830 has about the same amount of power as every other headunit out there. It's the same as every alpine under it, and the 9831. It's about the same as Pioneers. It's a little more than Sony. I wouldn't worry too much about headunit power.

can give you a big long spiel why you shouldn't, with lots of physics terms, or you can just believe me. I've been in the car audio business for 6 years now.
trippinbillies40 is offline   Reply With Quote
Old 08-03-2004, 09:53 PM   #3 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
15-22 watts RMS is the average amount of power one will find in an aftermarket head unit. That is generally sufficient for any oem speaker and many aftermarket speakers. What is more important, to be technical, is the type of amplifier in the head unit. An HU with a Mosfet amp is going to sound warmer and more natural than one without. It also yields a little more power per watt. Most if not all Alpine HU's feature such an amp these days, as does Pioneer and Kenwood.

As you go up in price (with regards to aftermarket head units), you get to a point to where there is no internal amplifier. Known in the industry as a "deadhead", these require outboard amplifiers to drive all speakers involved. This is ideal, and BMW is one of the few car makers that give you that set up from the factory.
__________________
jllphan is offline   Reply With Quote
Old 08-03-2004, 09:58 PM   #4 (permalink)
n00b
 
Join Date: Jul 2004
Car:
Posts: 30
Photos:
trippinbillies40 is an unknown quantity at this point
Not to be a jerk, but few? BMW, Mercedes, many Ford and Ford owned cars, many Toyota and Toyota owned cars do as well...
trippinbillies40 is offline   Reply With Quote
Old 08-03-2004, 10:00 PM   #5 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
Of the hundreds of car makers peddling their whares in 1995, yes BMW was one of the few to offer such.

Lesser companies have followed suit in recent years...
__________________
jllphan is offline   Reply With Quote
Old 08-04-2004, 02:53 AM   #6 (permalink)
2nd Gear Member
 
docrobot's Avatar
 
Join Date: Jan 2004
Location: Calgary, Alberta, Canada
Car:
Posts: 458
Photos:
docrobot is an unknown quantity at this point
Quote:
An HU with a Mosfet amp is going to sound warmer and more natural than one without. It also yields a little more power per watt.
ghead

By definition at www.dictionary.com:

watt

n: a unit of power equal to 1 joule per second; the power dissipated by a current of 1 ampere flowing across a resistance of 1 ohm.



Watt is used as the definition and rating unit for electrical power. So, a watt is a watt is a watt dude!

Now, if you are trying to say MOSFETs offer lower harmonic distortion so higher power is cleaner and therefore warmer, I might agree...

docrobot is offline   Reply With Quote
Old 08-04-2004, 06:07 PM   #7 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
I knew some guy was gonna say something about that comment!

I am terribly aware that Wattage is a measure of power.

What I mean is that a Mosfet power supply containing a true wound turrodial power supply will actual create a higher level of SPL than a digital amplifier chipset used in many lesser headunits.
__________________
jllphan is offline   Reply With Quote
Old 08-04-2004, 08:49 PM   #8 (permalink)
n00b
 
Join Date: Jul 2004
Car:
Posts: 30
Photos:
trippinbillies40 is an unknown quantity at this point
Please explain. Given the fact that a watt is a watt, no matter what kind of amplifier, be it mosfet, digital, heck, even an SET tube amp (god forbid you see one in a car), a watt is still a watt. Now, given that, the SPL is purely generated by the speaker, which varies in efficiency. Ergo, I speaker of higher efficieny, at any given wattage, is the only way to generate more SPL from equal mounts of power, discluding impedance.

MOSFET amps typically run much cooler than a digital amp, and when an amp heats up, so do the wires inside, and that creates impedance, which kills power, which in turn hurts SPL. It would be more accurate in my eyes to say that the MOSFET amps are more efficient and typically will sound louder because they put out more power after being driven like most people will drive them.
trippinbillies40 is offline   Reply With Quote
Old 08-05-2004, 08:55 PM   #9 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
Trippin, you basically answered your question for yourself! :lol:

Mosfet amps are more efficient. When input voltage, they do exhibit less heat. Why is this important? The more heat each component in a given piece of consumer electronics is subject to, the ability of the unit to transfer energy is lessened.

Not only that, but a true MOSFET power supply has a flatter frequency response. Used in conjunction with a set of oem speakers this may not be fully realized. With a decent set of aftermarket loudspeakers however, this is very easily noticeable. What is present is a fuller, warmer sound that translates more of the origional recording. The impression one gets is that of MORE POWER.

I really don't want to get heavy into a simple question, I mispoke regarding a valid point. I'm just saying a MOSFET equiped head unit is gonna sound fuller, better, and louder than one that is not, even if the two are rated @ a similar output power.
__________________
jllphan is offline   Reply With Quote
Old 08-05-2004, 09:31 PM   #10 (permalink)
n00b
 
Join Date: Jul 2004
Car:
Posts: 30
Photos:
trippinbillies40 is an unknown quantity at this point
As someone who has also been in this business for awhile, I never want it to seem like I'm arguing. I know that everday there is something new for me to learn, so I may question something if it is contrary to what i believe, or just is confusing or mis-stated. Trying to keep up on things.

But yes, you are correct. From what i have listened to, MOSFET amps do work very well in cars.
trippinbillies40 is offline   Reply With Quote
Old 08-06-2004, 04:18 AM   #11 (permalink)
PMB
1st Gear Member
 
PMB's Avatar
 
Join Date: Jul 2004
Location: Isle of Man
Car:
Posts: 200
Photos:
PMB is an unknown quantity at this point
With regard to the power it really does not matter what the unit says it will do, it cannot do more than the fuse will allow. Most 4x50 watt head units I have seen recently have 10 amp fuses. so lets do some maths.

4X50=200+30=230watts total. (the 30 is to power the cd's laser, lights etc.)

Now with the engine running in a perfect world a car outputs 14.4 volts.

14.4x10=144 (watts available before 10 amp fuse blows). -30=114 watts available

114/4=28.5 watts per channel MAXIMUM!

Manufacturers are not allowed to lie about power but they are allowed to say that it is possible to obtain 50watts form one channel (if the others are not running and that one channel is driven to destruction). So yes, 50X4 it may say, but is physically is impossible with a 10 amp fuse. Fuses do not lie. The 230 watts described above would need a minimum of a 16 amp fuse to be a reality.
PMB is offline   Reply With Quote
Old 08-06-2004, 11:58 AM   #12 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
Quote:
Originally posted by trippinbillies40@Aug 5 2004, 10:11 PM
I never want it to seem like I'm arguing...

Trying to keep up on things.

It's all good bro. I mispoke and used improper grammar. I would hope anyone on this forum would question any of my statements if they don't understand or disagree. I would hate to not help or more importantly misinform anyone.


PMB: Yes, you have figured out that peak or maximum rated output power is a superfluous rating. Often times a head unit's max. power output is found when more tha 14.4V is sent to it. While this illegal, it is often times the case.
Also at this max. power, the unit is dishing out enough distortion (approaching DC) to blow almost any speaker.

I've said this many times before (and will many times again ) one must only pay atttention to RMS or nominal output. That rating coupled with the rated THD and SNR of a given power supply is the best way to compare one from another...
__________________
jllphan is offline   Reply With Quote
Old 08-09-2004, 08:29 AM   #13 (permalink)
PMB
1st Gear Member
 
PMB's Avatar
 
Join Date: Jul 2004
Location: Isle of Man
Car:
Posts: 200
Photos:
PMB is an unknown quantity at this point
JLPHAN, you are right except that when doing the RMS rating they will never state "all channels driven". The RMS rating is single channel. So I stick by my guns the only true way to tell how powerful and amp or head unit is is by the value of the protection fuse!
PMB is offline   Reply With Quote
Old 08-09-2004, 10:15 AM   #14 (permalink)
WOT in Reverse
 
jllphan's Avatar
 
Join Date: Jan 2004
Location: Cashville, TN
Car:
Posts: 3,441
Photos:
jllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond reputejllphan has a reputation beyond repute
Send a message via AIM to jllphan
That's a great formula, but technically speaking a manufacturer could drop in any size fuse they wish. It's not like a 40amp fuse is gonna drive up production costs. Granted they don't wish to allow too much current to enter the head unit or they will see a lot of repairs, but I'm not sure that the supplied fuse is gonna be consistent from company to company (i.e. some may differ in what they feel necessary regardless of rated output)

Either way guys, don't be fooled by the impressive figures on the front of the deck (or outboard amp these days) as those are peak ratings, and even those are a little optimistic.
__________________
jllphan is offline   Reply With Quote
Old 08-10-2004, 01:10 PM   #15 (permalink)
2nd Gear Member
 
docrobot's Avatar
 
Join Date: Jan 2004
Location: Calgary, Alberta, Canada
Car:
Posts: 458
Photos:
docrobot is an unknown quantity at this point
At least some online stores like Crutchfield display the advertised wattage which they call peak output, and RMS wattage on the same page.

Here is what they say: Peak power is measured during a brief musical burst, such as a sudden drum accent. Some manufacturers display peak power ratings on the face of their products. The RMS power rating is more significant, and we recommend using it for comparison purposes.

Large sites like Crutchfield are excellent for comparing specs on different models and brands, they also have the car audio accessories most e-com sites leave out.


n Before I get flamed for working at Crutchfield let me just say; It's just too bad that they charge way too much for it's H/Us!

I mean the local Best Buy up here in Canada wants $369 (Canadian) for that Sony CDX 8805X that I have the hots for, and Crutchfield wants $359 American!!! (XE.com says that $369 Canadian is about $280 American!) WTF???
docrobot is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  BMW Forum - BimmerWerkz.com > General Category > Audio and Electronics


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
5 series head unit to amp question. Non DSP greenwave 5-Series (E12,E28, E34, E39, E60) 6 06-28-2007 10:23 PM
CD changer compatibility with aftermarket Head Unit Teh Prof Audio and Electronics 2 11-07-2005 05:22 AM
If I Change My Head Unit... OldGuy Audio and Electronics 1 02-27-2005 09:18 PM
Cd Changer Adapability nookatee Audio and Electronics 5 02-05-2005 11:36 PM
OEM changer and head unit mystery BobCT Audio and Electronics 4 08-04-2004 11:50 AM

Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 09:14 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.3.2
Garage Plus vBulletin Plugins by Drive Thru Online, Inc.