[kiran1103]

Hello,

My present setup is

Front Comp : JBL 607c (70RMS @ 2 Ohms)
Rear Coaxial : Poineer TS-2150 (50W RMS @ 4 Ohms)
Amplifier : JBL GTO 504

The above setup was good as the Amplifier almost matched the speakers ratings.

Now I just got an GTO 1004 amp which is 150 WRMS @ 2 Ohms and 100 WRMS @ 4ohms.

Now if I replace the GTO 504, I will be overpowering the speakers. Is this ok? and what precuations should I take to run them safe if I want to run the above speakers with this amp.

I am planning to keep 1004 because in future I may upgrade my Comps to Infinity Kappa or Alpine Type R which are 90 WRMS and Rear coaxials to any 100WRMS 6 X 9s.

I have searched this forum and found that overpowering is always good but not sure of the safe range. i.e., 150RMS amp powering mere 70RMS comps?

Hope I am clear. Thanks

[abhinav.gupta88]

I was using the JBL 607c with the 1004 and a friend is using it currently.
There isn't any issue.

Just set the gains a bit low ( that's what i did)

[kiran1103]

Setting the gains a bit low here means turning down the Input level. Should the input level be matched to the HU's pre-out voltage? In my case its 4 volts.

[karankapoor]

Amp should match the input voltage from the hu to avoid clipping, Keeping the gains low will not make any difference. Set the gains properly and you are fine with it.

[mohitd]

As long as you keep it low there wont be any problem.

My friends 608c's couldn't take the power from the 1004 and had to be replaced.
The coils of one of them got burnt.

[abhibh]

Originally Posted by mohitd

As long as you keep it low there wont be any problem.

My friends 608c's couldn't take the power from the 1004 and had to be replaced.
The coils of one of them got burnt.

As KK said lowering gains wont help much if voltage from HU preout is more.

AFAIK JBL GTO608C are 70W RMS and 1004 supplies 100W RMS. It seems like the gains were not set correctly and due to the clipping components gave up.

[DerAlte]

Don't worry too much about the power numbers. If you are listening loud, reduce volume just when you find distortion setting in. In normal listening conditions, the amp will feed just what is needed, not the rated power. If you push too much, your speakers might get fried, but long before that you will hear very irritating speaker distortion - like some clearing their throat.

[abhinav.gupta88]

@ Abhibh , the 608c are 2 ohms components and not 4 ohms.

At 4 ohms , the 1004 gives about 150w

[navin]

Originally Posted by DerAlte

Don't worry too much about the power numbers. If you are listening loud, reduce volume just when you find distortion setting in. In normal listening conditions, the amp will feed just what is needed, not the rated power. If you push too much, your speakers might get fried, but long before that you will hear very irritating speaker distortion - like some clearing their throat.

DA, I dont want to generalise here especially since most ICEers on TBHP are a bit more knowledgeable than the average owner of audio but I suspect that many here are not listening to the speakers. By this I mean most speakers (a few very delicte tweeters, and some riboon speakers apart) will complain (distort) long if abused. If the music becomes intolerable to listen to in many cases it is due to distortion.

On many an occasion my friends tell me that my system is not loud then I ask them to speak with the system (volume at 12 o clock) playing and they realise that they cant hear themselves (that is awful loud and dangerous for long periods). Some audio systems can give the impression they are loud (because the ear confuses loudness with distortion) because they are not clean.

In short listen to the music and the system. In most cases you will hear the abuse well in time to turn it down and protect the system and maybe your ears too.

Appologies to anyone who feels that they are being targetted. The above statements are a simple generalization. I expect TBHP ICEers to be knowledgable enough to protect their ears and systems.

Human science understand more about the human eye and docs are able to correct for many abnormalities and deficencies of the human eye (cataract, macular degeneration, etc..). The human ear is not as well understood (just ask anyone who has lost hearing and is dependant on a hearing aid) and simple hearing loss is much more diffcult to correct than vision. Some of this is due to physics of sound (longer wavelength, reflection and refraction, etc..) and also the way our ear-brain neural system is set up (compared to the eye-brain). For example we can listen to music many times and not bore of it but try viewing the same movie as many time.

This should give everyone more incentive to protect their hearing.

[DerAlte]

You are right, Navin, and most of the times we get caught up in the numbers game - X watts speakers and Y watt amp, but one never looks at the THD numbers. Most of the times distortion is misunderstood to be part of music.

There was a time not far back when most systems were preferred to be treble-heavy (arrey, what system do you have, huh? One cannot hear the chilla-chilla outside?). Everyone and their aunts & uncles wanted to add a tweeter to the whizzer-cones. Today such systems are relegated to autos. And what did one actually hear? Overpowered distorted highs.

Then came the age of the mandatory boofer. No matter if the boofer sounded like a bad case of flatulence, the 'system' is not worth its money if the boom does not make heads turn. The preferred music today serves only as the German word 'takt' - no other relationship is required between music and listener, the music serves to help keep step as drum beats in marching.

If that relationship is missing, one does not notice any flaws since there is no expectancy set.

[kiran1103]

Yes agreed. I too believe in quality of sound. I have noticed that many dont like Bose systems as they dont seem to be loud (which they are used to think that loudness in system means good quality). I argue with everyone who dislike Bose home theatre system and stress on quality of sound and the detail that it produces.

btw I have set the inputs dial to low and using it and the quality has increased comparively from my earlier GTO 504.

[Invinsible]

In addition to what everyone suggest, here is an article that might help one understand better Overpowering, Underpowering, Distortion, Clipping, and Everything in Between [audiojunkies]

Whatever you do/decide, if you 100W/channel on 70W speakers, setting the gains and xover point careful you may get better result, as in more clean sound since the gain would be lower compared to using a 70W/channel amp. Which means lower distortion, most of the time it's the distortion that destroys the speakers more than overpowering. Use an help of an expert installer and you should be fine with whatever you decide.

[navin]

Originally Posted by kiran1103

Yes agreed. I too believe in quality of sound. I have noticed that many dont like Bose systems as they dont seem to be loud (which they are used to think that loudness in system means good quality). I argue with everyone who dislike Bose home theatre system and stress on quality of sound and the detail that it produces.

Bose is a hotly debated topic on many a forum. Lets not go into Bose debate here. They are never ending.

Originally Posted by DerAlte

You are right, Navin, and most of the times we get caught up in the numbers game - X watts speakers and Y watt amp, but one never looks at the THD numbers. Most of the times distortion is misunderstood to be part of music.

Now lets take this to the next level (this has been discussed before).

Say you have a common 6" component system rated at 70W rms. I can assure you that I can damage that system with less than 70W and I dont mean the tweeter which can be destroyed by simply passing a clipped singal, I mean the woofer as well. How? well 70W rms at 30Hz will severly tax the woofer, 70W at 100Hz will not. Put 70W at 30Hz into the woofer an the voice coil will detach just from the excursion. It is that simple. In fact (after the advent of ferro fluid) more tweeters today are damanged from over excursion (tweeter excursions are of the order of 0.1-0.5mm) than from too much power (point to note that ferro fluid is not without side effects).

Lesson: You need to consider a lot more than just "wattage" numbers. Wattage numbers for what they are worth are more advertising than any sense. Numbers I would need to determine if the woofer/tweeter is well built (how it sounds can only be done by ear and taking FFT distortion measurement) include Bl, Mms, Cms, Vas, Fs, Qts (Qes & Qms), Xmax (linear one way) & Le. Watts as you see is not even something worth seriously considering.

[DerAlte]

Originally Posted by navin

... Wattage numbers for what they are worth are more advertising than any sense. ...

You are right. Working with Sales guys and ad creators for the last 20 years, I realized the basis is simplistic thinking. Advertising and numbers are interdependent:
* ad creators,who actually do not use any of the products they create ads for, cannot figure out what to write other than numbers, flowery language, and qualities which have more to do with ease of manufacturing / assembly and less with actual use
* consumers would like tangible data to compare
* tangible data manifests itself in the form of numbers etc., and
* finally there is the one-up-manship game where numbers are used for the sake of creating an artificial differentiators in the mind of the consumer
Funny thing is, this approach works with stuff that most people would anyway have bought on the basis of cost, even if they hadn't looked at the numbers. Unfortunately, it works against what is out there that is actually better.

The fault also lies with Engineering people - we fail to realize that the physics, chemistry and maths the way we tend to present them, does not automatically create an understanding of what affects what in actual use, how, and why. That creates a situation where most consumers think that if I don't understand the why's and wherefore's of Q, BL, Vas etc. let me keep my life simple and go with a. brand and b. numbers.