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Old 1st September 2009, 11:45   #1
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Default Need for Amplifier in a setup to be always played a low volume.

Dear Gurus,

I have a lingering question in my mind , I

Suppose there is a car audio setup with component speaker and no dedicated sub woofer That is biggest speaker diameter is maximum 6.5 inch
or 8/9'' in case of ovals ? The setup is always going to be played at low volumes ( That is volume below which HU inbuilt amplifier sounds good / does not crack).

In such a setup is there any need for a dedicated Amplifier ?
If answer is Yes how exactly can amplifier better the sound over the stock HU amp output of 10W RMS.

Is the stock HU output power not good enough to drive 6.5'' or an 8'' speaker diaphragm for it's full range of movement ?

I used search feature but got no clear technical reason.

Regards
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Old 1st September 2009, 11:55   #2
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Bridge the rear channels and make more power and buy small woofer may be 8" and enjoy, if you need more theres no limit.
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Old 1st September 2009, 11:58   #3
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Typically amplifiers improve the sound not just the decibel levels. At the same decibel, a powerfully amplified sound will sound a lot better than straight from the 10w HU amp.
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Old 1st September 2009, 12:08   #4
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Quote:
Originally Posted by esteem_lover View Post
Typically amplifiers improve the sound not just the decibel levels. At the same decibel, a powerfully amplified sound will sound a lot better than straight from the 10w HU amp.
Well the question is how amplifier improves sound ? Amplifier should maintain the fidility of the input and as per definition should only increase the output waveform amplitude with least distortion.

I could not understand much from above answer Decible level means sound output measured and is directly proportional to the amplitude of the electric waveform being fed to speaker.
from technical point of view Amplification means higher decibel level so one can not call an electric waveform as amplified if the output decibel level is exactly same ( until the same decibel level is being achieved by some sort of uniform damping of the speaker diaphragm or changing the speaker).
Here the speaker is a constant,

Well I read the final conclusion always ( install an Amp) but no technical reason is provided ever so started this new thread.
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Old 1st September 2009, 12:28   #5
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okay, lets try to address your question. You say that the amplifier that is built into the head unit gives you a power output of 10 watts so i would assume that if you attempt to play the amplifier into providing the speaker above 10 watts then it will start clipping. light clipping does not necessarily damage a speaker but as the clipping increases the sound will begin to distort and sound strained

the idea is to apply more power to the speaker and play the speaker at a more restrained volume level so that you dont make the amplifier clip hence it will not distort or strain. Now by playing an amplifier that can provide a lot of extra power ... or what we can term "headroom" since we are not straining it it will stay cooler and for any electrical components not placing any strain which leads it to play cooler is a good thing because this reduces electrical resistance within these components and also increases the components life expectancy

I personally prefer to use lots of extra headroom even if i want to be playing the system softer because its not the power that will strain a system, it is more when you abuse the power or demand more than a system can give that you begin to damage equipment

so you buy a speaker that claims that it wants 60 watts continuous, so then you play to that soft volume level but you are only giving it 10 watts then you start up the car and it sounds soft to you - so you try to lift up the volume and the amp cannot supply enough power but you think to yourself "the speaker can take 65 watts so im only giving it 10 watts, so i can pick up more volume" and it begins to clip considerably more - then you carry on picking up volume because according to you the speaker should be able to take the low amount of power, but what it cannot handle is the abuse of trying to make that 10 watts play transient moments in the music to volume levels that you would like

so imagine instead with the same speaker from our above example where you actually purchase a 150 watt power amplifier. You then set the gain with an oscilloscope to a level where the amplifier will not clip so you have 150 watts going to the speaker but because of the power and headroom you only need to have an even lower volume level and even when you start up the car and drive down the road the road noise and wind noise as well as the exhaust noise and even the tyre rumble will be affecting how you hear the music but because of the large amount of power on tap you still only need to increase the volume level at a reduced rate. So now you are not inducing clipping and the volume level is not very high, nothing gets strained and nothing plays very hot but the music sounds loud and clear and undistorted and still is able to play above the typical noises that can inhibit your musical enjoyment

so to me this is where an amplifier is very important, if your home system needs 100 watts of power per speaker imagine how much a cars speakers would need to overcome all of those noises and still play undistorted. Though it still needs to be a balancing act of knowing when you are exceeding what the speaker can handle for example if you intend to use all 150 watts from the amplifier then get a speaker that can handle the 150 watts instead of 65 watts, if you use a speaker that needs 65 watts and have an amplifier feeding it 150 watts you still need to be honest with yourself when it comes to distortion in the transients. Some people will think oh ive just heard a small bit of strain in the speaker but it will handle a bit more and eventually the resultant distortion and clipping due to overpowering the speaker will surely kill it just as quick as not feeding enough power and picking volume levels too high

its all about balancing your equipment to your needs, i hope that this addresses the reasons behind your question a bit more

Last edited by naughty001 : 1st September 2009 at 12:30.
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Old 1st September 2009, 18:49   #6
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Thanks naughty , avoiding Clipping looks logical.

Does the distortion of sound happens through out the range with an in an inbuilt 10 W RMS amplifier or shall we assume that clipping will happen once the output level is more then certain maximum.

Putting the question other way 10 W RMS means that on an average the peak should be around 13 W or slightly higher and still there may be certain sharp peaks which will get clipped so by capping the volume level still lower can it be ensured that no peak crosses the clipping point ?

One more question does under powering the Speaker destroys it ?
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Old 1st September 2009, 20:05   #7
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* Clipping will happen when parts of the music, when amplified, exceed the voltage of the output stage (saturation)
* Yes, it is throughout the range.
* Yes, it is unlikely that at low amplification levels distortion will set in
* The power level is rather difficult to determine, since it is dependent on frequency and speaker impedance at that frequency. For convenience, everyone talks of the declared numerical figures, with a couple of factors like supply voltage ignored
* Unlike human muscles, which can suffer from atrophy, speakers do not exhibit such characteristics when under-utilized

Quote:
Originally Posted by naughty001 View Post
... the idea is to apply more power to the speaker and play the speaker at a more restrained volume level so that you dont make the amplifier clip hence it will not distort or strain. ...
Speaker, being a passive component, will only move as much as the current that is flowing through it's VC (simple view, for the time being ignore frequency/momentum/other-dependent behavior). That current is dependent on the instantaneous voltage at the output, which is dependent on the effective amplification of the signal, which is dependent on the volume control setting. At a certain Vol setting, there is no question of 'pushing' less or more power into a speaker. Nor is it possible to push more power and get only 'more restrained volume level'!

Physical distortion of a speaker can occur when the Xmax is exceeded, so it is always better (in general, since it is not only power that is related to it) to use an amp of a lower capacity than the speaker. Onset of distortion (nauseatingly horrible!) would / should cause the listener to reduce volume.

The headroom logic, that peaks in music passages should continue to sound naturally proportionate to the rest of the music, and not land up being distorted, is correct.

Honestly, I could never understand the common suggestion that 'speaker should be driven to its FULL potential by feeding full power of a powerful amp'. Like wanting to red-line your engine in city traffic, the resultant effects are likely to be disastrous if that actually happens.
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Old 2nd September 2009, 09:03   #8
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Quote:
Originally Posted by DerAlte View Post
* Clipping will happen when parts of the music, when amplified, exceed the voltage of the output stage (saturation)
* Yes, it is throughout the range.
* Yes, it is unlikely that at low amplification levels distortion will set in
1 and 3 are in Synch but contradicts statement 2.
How is it throughput the range ?

Quote:
Originally Posted by DerAlte View Post
* Unlike human muscles, which can suffer from atrophy, speakers do not exhibit such characteristics when under-utilized
LOL Yes I fully understand that but question had another layer to it if you refer to Naughtys' explanation.

Suppose the speaker is being fed with an amplifier ( external or output stage of HU) such that amplification level is lower then rated capacity of speaker.
Now going by the explanation provided earlier whenever the system is played at a max volume level certain peaks will be clipped , Any kind of square wave always result in harmonics.
o won't these harmonics distroy the speaker diaphram ?

Is it not better to keep the max output of AMP equal to Speaker ?

Last edited by amitk26 : 2nd September 2009 at 09:07.
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Old 2nd September 2009, 12:18   #9
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Quote:
Originally Posted by amitk26 View Post
... How is it throughput the range ? ...
(I assume by "throughout the range" you meant "at all frequencies") Clipping is frequency-independent, i.e. no matter which frequency or combination of frequencies the signal envelop has (what one can see on an oscilloscope, or what the ear hears), clipping is saturation of amplification at output. Saturation is that state that the amp cannot amplify the signal any further, and the output voltage stays constant for the period that this happens.

This period is actually very short (only peaks exceeding supply voltage are clipped), and since the transition from normal envelop to saturation is a step (not smooth), this appears as a quasi-square wave at the output. As you mentioned, the harmonics in this unnatural square wave are what you hear as distortion superimposed on music. The whole music does not distort, only the sources whose peaks have clipped. Unfortunately the whole music experience then actually sounds terrible to us!

Quote:
Originally Posted by amitk26 View Post
... Suppose the speaker is being fed with an amplifier ( external or output stage of HU) such that amplification level is lower then rated capacity of speaker.
...
won't these harmonics distroy the speaker diaphram ?
LOL You are confusing yourself by not considering all the Use Cases!
1. Some speakers mention Power rating as, e.g., 8-120W. Why? 8 watts in this case is the minimum power required to produce music at normal audible levels (not requiring us to take our ear to the speaker ). If this figure were to be, say, 16W, it would be unsuitable for driving from the HU (internal amp about 14W rms). This minimum power is most of the time indirectly inferred from the sensitivity figure (lower dB = less actual loudness for the same power)

2. "Rated capacity" of a speaker (120W in the above case) is an average power level which the speaker can be played at continuously for hours without failing. "Maximum Power" is the power which if actually sent through the speaker is likely to fry the voice coil. Neither of these are *absolute* figures, since actual usage with associated air flows and thermal conditions may or may not cause the Rated or Maximum condition to be reached

3. What power *actually* flows through the speaker at any given moment is rather very difficult to calculate - it varies with music. Look at it this way: if one takes FFT of a piece of music with 256 discrete components (most common), the summation of electrical power corresponding to each of these components is the actual power flowing into the speaker. Even this is a mathematical approximation (256 discrete samples, not all of the signal). By this you should realize that saying "feed rated power into the speaker" is not a very logical thing to say

4. Your expectation of harmonics is very correct. However, you should realize that the harmonics are as much valid frequencies as any music. ONLY a human brain differentiates between music and noise, relying on previous learning and experience. How else would we differentiate between intentionally introduced guitar distortion, and incidental clipping at the amplifier while reproducing the signal???
Will the artificially produced harmonics deteriorate any speaker component? NO! But ...

5. It is the 'square wave', or more precisely the step transition in power which is the difficult thing. A discrete step, as opposed to a smooth signal, especially at high power levels, induces very high acceleration in the moving parts. This 'jerk' can cause joints (VC, spider, cone, surround) and material faults (in cone and spider) to gradually / ultimately fail. Very similar to sports injuries like shoulder dislocation in 'throwing' sports

Whether <, = or >, the relationship is more a matter of getting the right amp rather than simple numerical matching. A comparatively terribly underpowered amp may sound really good, and a numerically matched one absolutely hopeless. My decision-making is simple: I never intend to fry voice-coils, which is a distinct possibility if Amp power >= Speaker rated power.
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Old 15th September 2009, 21:10   #10
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Quote:
which is a distinct possibility if Amp power >= Speaker rated power.
source =
Live Sound: How Many Watts : Amps vs. Loudspeakers - Pro Sound Web

“So how many watts can this loudspeaker take?” The technical answer is that it depends on the thermal and mechanical limits of the drivers and crossover components. The practical answer is that it depends on the program material played: its peak/average ratio or transient content, and spectral (frequency) content. The REAL question is not what is the power handling, but what is the OPTIMUM size power amplifier to use on a loudspeaker?
Rule of Thumb
For a Rule of Thumb the best answer is found using the loudspeaker’s RMS Power Rating. Use an amplifier that is twice the RMS rating. If you can’t find an amplifier with that exact rating, multiply this power rating by 0.8 and also by 1.25 to find a range of acceptable power.
Example: A loudspeaker has a 250W RMS rating. Twice this is 500W. Therefore the acceptable range for the power amplifier to use is from 400W (0.8 x 500) to 625W (1.25 x 500). Anything larger is potentially excessive power. Anything smaller can cause damage from the amplifier clipping. Remember that the power amplifier output you select must be rated for the nominal impedance of the loudspeaker (i.e. 16, 8, 4 or 2 Ohms).
The RMS rating represents the thermal power limit for the loudspeaker. It is also a good number to use for comparing products. Twice the RMS rating represents a realistic scenario for most actual audio signals. This is 3 dB more power than the RMS rating. An amplifier’s RMS rating is based on a sine wave measurement. The peak power in a sine wave is 3 dB more than the RMS power. Therefore using twice the RMS power rating for the loudspeaker provides 6 dB more power for short term power peaks.
A good loudspeaker can easily handle this. Why? The RMS rating for professional loudspeakers is almost always measured using pink noise for a test signal. The content of this test signal is an RMS level with peaks that are 6 dB above the RMS level. Thus testing a loudspeaker with pink noise requires an amplifier that can produce power peaks of 6 dB above RMS level of the input signal to the loudspeaker without clipping. The Rule of Thumb provides an amplifier with this capability.
Real World Audio Signals
Real audio signals usually have peaks at least 10 dB peaks their RMS level. Therefore, with a properly sized amplifier just below clipping on those peaks, the RMS value of typical audio signals will be at least 3 dB below or 1/2 the loudspeaker’s RMS rating. This provides a margin of safety.
Still Possible to Damage a Loudspeaker
Having said this, it is entirely possible damage a loudspeaker with an amplifier that is in the “Rule of Thumb” power range. Why? Because power handling depends on the type of input signal and the user, not the manufacturer, controls the input signal in actual use. For example, the RMS and peak levels can be about equal on compressed audio signals and for certain signals from instruments like synthesizers or highly processed electric guitars. This means any amplifier power capability above the loudspeaker’s RMS rating can damage it! Also, no matter what size the amplifier is, clipped signals are death to loudspeakers, even if the clipping occurs in the mixer, equalizer or other signal processor.
There is not a perfect answer to the power handling question. This Rule of Thumb is a realistic guide for the optimum size power amplifier to use on a loudspeaker for MOST live audio signals. It allows the loudspeaker to be used to its maximum specified power rating.
Caveat About Distortion
Almost no loudspeakers are rated for their distortion at maximum power. For this reason there is nothing implied by the manufacturer in the maximum power rating that says a loudspeaker will still sound good at its maximum power rating. If you find that a loudspeaker “sounds bad” when run near its maximum rating then the maximum distortion that you find tolerable will be the limiting factor rather than the maximum power rating.
Note: This applies to professional loudspeakers from reputable manufacturers. This includes drivers as well as complete loudspeaker systems.

that is what the link says - it makes sense to me personally - others may disagree

BTW i actually used a total of 2000 watts RMS of amp power for an older system of mine and because i was never enthusiastic with my headunit volume control - it suffered no ill effects whatsoever - i had a phoenix gold 200 watts RMS x 4 amplifier connected to a set of tweeters and midwoofers in active mode and another phoenix gold amp rated at 1200 watts RMS for the sub (morel ultimo which handles up to 1000 watts RMS) - every single item still works to date even though it is not me using them anymore

that system had amazing headroom and dynamics - it even improved when i replaced the Ultimo sub with a JBL W15GTI mk2 - still amongst the better systems ive owned up to now

Last edited by naughty001 : 15th September 2009 at 21:20. Reason: correcting spelling errors
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Old 29th September 2009, 14:43   #11
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I am layman in terms of sound terminology being discussed above.
I want to choose an amplifier for my music system. First My current configuration

1) Vehicle Indica Vista Aura
2) HU: OEM clarion
3) Front: JBL GT5-S265c Components
4) Rear : JBL GTO 947 6"x9" Ovals.

Currently I am driving all these good speakers with crap head unit. Initially I was satisfied because at that time I compared output with OEM Speaker Setup. Now I am having feeling that I am under utilizing my speaker setup. And I can get significantly better output with addition of Amplifier. I want to drive all the speakers with an Amplifier so I need four channel amplifier. I dont want to spend lot of money on that. Based on this I have shortlisted following Amplifiers.
1) Sony XPlod XM-ZR704 MRP Rs.8990
2) Sony XPlod XM-ZR6042 MRP Rs.5990
3) JBL GT5-A604 MRP Rs.7990
I do not know actual prices of these amplifiers. But I am looking for Amplifier around Rs.6K. Please suggest me good amplifier with road price...

Thanks

Last edited by sushantr5 : 29th September 2009 at 14:45.
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Old 29th September 2009, 14:57   #12
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My purpose of starting this thread was very specific to understand and clarify the need for Amp in technical terms.
Perhaps you should post your query in ask the gurus section.

Quote:
Originally Posted by sushantr5 View Post
I am layman in terms of sound terminology being discussed above.
I want to choose an amplifier for my music system. First My current configuration

1) Vehicle Indica Vista Aura
2) HU: OEM clarion

Currently I am driving all these good speakers with crap head unit.
Clarion is not crap unit it is a very good brand just ask how much a Clarion HU retails for in Market. Just because some VFM manufacturer bundles it that does not make a HU crap.

On the other hand Sony is considered Cr**p by people over here.
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Old 29th September 2009, 15:31   #13
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Hey amit. I was in the same dilemna as yours when I started with the ICE for my car.
I tested a pair of co-axials (Polk db690) with and without an amp and what I found was the speakers sounded better at the same volume with an amp. When connected directly with the head-unit, the sound is a bit subdued and a bit too laid back! But they came to life when powered with an amp (JBL/not sure which series). Presently, am running them from the head-unit as their laid-back sound doesn't interfere much with the front components which are powered by an amp.

@sushant
You can look for Kenwood 8401 / JBL S644 / Kenwood 845 amps in the 6k range.
Checkout the forums for reviews. I hope the Clarion head-unit has atleast 2 RCA out?
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