Cekap Brains....

[Shamanraj]

You know....there are many acc shops out there that dont know a thing about installing ICE...all they wanna do...is sell you stuff...thats all...its all about making money. Recently a friend of mine changed his CD(pioneer DEH1800) player cause his old one kaput. While installing he decided to throw in a 2 Channel Amp just as to improve sound clarity. His head unit is rated at 50W x 4. This is what the installer did.

1. Pre-amp output from head unit to AMP output using cable (Low Sig input)...no issue here.

2. Amp 2 channel output to Rear Speaker, Front Mid Speaker and front tweeter....here is the prob.

I mean...how dumb could this person be???? The head units High Outputs should have been directly connected to the front speakers and only the rear should have gone through the AMP....now front 2 Channels aint working so cant adjust fader. Guy claims this is how it should be done..."saya sudah lama pasang ini wo...."

 

[hi1983]

that is stupid shop. acually shop want earn, but some earn in bad ass way

 

[oldskolboyz]

You know....there are many acc shops out there that dont know a thing about installing ICE...all they wanna do...is sell you stuff...thats all...its all about making money. Recently a friend of mine changed his CD(pioneer DEH1800) player cause his old one kaput. While installing he decided to throw in a 2 Channel Amp just as to improve sound clarity. His head unit is rated at 50W x 4. This is what the installer did.

1. Pre-amp output from head unit to AMP output using cable (Low Sig input)...no issue here.

2. Amp 2 channel output to Rear Speaker, Front Mid Speaker and front tweeter....here is the prob.

I mean...how dumb could this person be???? The head units High Outputs should have been directly connected to the front speakers and only the rear should have gone through the AMP....now front 2 Channels aint working so cant adjust fader. Guy claims this is how it should be done..."saya sudah lama pasang ini wo...."

Nothing prob lee..... HU + 2ch amp... there has 3 option/way to use lorr..

a) 2ch Amp drive front comp/speaker & rear comp/speaker direct connect to HU
b) 2ch Amp drive rear comp/speaker & front comp/speaker direct connect to HU
c) 2ch Amp drive front & rear speaker/comp but need to sacrifice fader function..

Option a & b, when the HU built-in pre-amp capable to drive comp/speaker directly or enough pwr.. Option C, when the HU built-in pre-amp not capale to drive comp/speaker directly.. mean your comp/speaker need lot of power... let say your comp/speaker rate >100wrms... do you think <20wrms from HU can power it up? I dont think so laa frend... somemore your HU only have rear RCA output or 1pair RCA... Rear RCA output doesnt mean only for rear speaker.. U can manipulate it.. U run for front speaker or whole system... I also did know & confuse... either the acc shop try con you or you didn't know anything about it... paiseh... paiseh...

 

[Shamanraj]

Well we just wanted the amp for rear. Front speakers can be driven by the 22W*4 (continuous power output) as the "RMS" of the speaker is lower than this. Now a lesson on "RMS".

Power is energy per time. It is measured in watts. Power delivered by an amplifier to a load (speaker) is normally determined by dividing the voltage (V) squared by the impedance (Z) :

V²
Power = -----
Z

The resulting type of power will depend on what voltage we use. If peak voltages are used, then the result is peak power. If RMS voltages is used, then average power (often wrongly referred to as "RMS") is obtained. RMS (root-mean-square), is only a mathematical method to extract the mean value of an alternating signal (one with negative as well as positive values).Power is only positive (goes from the amplifier to the speaker, not the other way round), so does not need the "root" and the "square" of the RMS process (which just extract the sign out of a number), just the "mean" (average). Average power is therefore that which uses RMS voltage for its calculation.

A 150-watt lightbulb presents a constant 150-watt load to an electrical power source when it is on. By contrast, a 150-watt audio amplifier will only rarely be called upon to deliver its full output to a loudspeaker. Same goes for the HU where it will rarely be called upon to blast out 50W from each channel. Thats instantaneous power capability.

So for normal conditions, we would want the HU to deliver a continuous power output of less than 22W per channel for the front (cause audio settings been tuned) and the amp to supply to the rear with a stable output. This was we get quality well balanced sound instead of BOOM....BOOM....BOOM....ching...ching...ching....

Though this might help guys.

 

[Zenn]

actually for better sound u should use the 2ch amp to power the front components (mid & tweet via passive crossover) and run the rear speakers via the HU inbuilt power.

this way he will get a good front sound stage (sound comes like there is a stage facing you) and the sound from the rear is just for ambience (use fader to front more than rear). so we use the smaller power from HU to power the rears and the bigger power from power amp for the fronts.

the acc shop connected both front & rear to the 2ch in parallel making it run in 2ohm which makes it hot, also the power is divided by two for front & rear. this one is ABCD type of sound (ada bunyi cukup dah)....but nothing really wrong with his connections, just that there is another way to get better sound..

 

[craziechild]

not really wrong about the connection... as long as the amp doesnt overheat...

i agree with zenn idea too on connecting the amp to the fronts so tht the staging would be better... but then some ppl might feel tht rear staging sound better...

cheers...

 

[Shamanraj]

Zenn,

you seem to know what ur talking about. I agree with you...its either front, back or centre. Anyways...."ada bunyi cukup" installer forgot to tune the amp's Bass, Tone and overall gain. It was all set to 0dB and thats why it sounded so bad even if we increased the HU's low, mid and high gains. Just did minor adjustment and ABCD sounds better...better tonal and highs&low. Gonna tune it properly later. Just wondering if the guy that did this was only thought "red go here....black go here...then the others...put anywhere...dont care...as long money come no issue"

 

[Shamanraj]

Zen,

Dude...what do you do for a living man.....??? High fidelity???

 

[oldskolboyz]

Zen,

Dude...what do you do for a living man.....??? High fidelity???

Shamanraj, it doesnt matter either High fidelity or not .. but U should look at his signature loorr...

 

[Zenn]

curently unemployed...:cry_smile:

 

[DJThoRmented]

but a winner... buahahahahahaahahhahahahaha...

I've been to an installer of your case. To bad for him it was the 1st and last. All I asked was one thing and he added more and tried to even bull me more ha ha ha... too bad.

Re-wire the amp for front, yes it will be better.

Sorry to hear of your experience.