Is more or less better?

Ashish · #1 11-05-08, 11:24 AM

I have a pair of MS 906i floor-standing speakers (Power rating - 15-150watts, Nominal impedance - 4-8Ω). What Power Output should I go for the amplifier – less than 150 watts or more than 150 watts?

dinyaar · #2 11-05-08, 11:35 AM

Hi Ashish,
Its not all about watts. Some amps drive better even though they may be modestly powered. Depends on the way its made. I presume u are referring to solid state amps.
What amps have u shortlisted for ur speakers? How sensitive are ur speakers? If they are closer to 90db then a 100 watt amp will be more than sufficient in a reasonably sized room.
Regards

odyssey · #3 11-05-08, 12:23 PM

As Dinyaar mentioned, if its 90dB, a 100W is more than enough, in fact its an overkill. Just make sure that whichever amp it is can supply enough current, in short go for a high current amp, it need not be a high wattage amp.

cheers

awedeophile · #4 11-05-08, 12:27 PM

As Dinyaar rightly pointed out, this depends on the sensitivity of your speakers. Use the following calculator to see the sound pressure level with reference to the speaker sensitivity and amplifier power (Watts).

Peak SPL Calculator

A speaker with a sensitivity of 85 db SPL will need 300 Watts to give the same output level as a speaker with a 100 db SPL driven with 10 Watts!

Also are your speakers 4 ohms or 8 ohms? You need double the power to get the same output level at 4 ohms as against 8 ohms.

Kamal · #5 11-05-08, 06:42 PM

Awediophile wrote-
You need double the power to get the same output level at 4 ohms as against 8 ohms.

?

awedeophile · #6 11-05-08, 06:57 PM

For a given output a speaker will draw twice as much current from the amplifier at 4 ohms than at 8 ohms, all other parameters being equal.

Ohms Law - I=V/R

Ashish · #7 12-05-08, 10:59 AM

Dear Friends,

What I meant to ask was what is better for speaker (health), more wattage or less wattage from amp. I understand if the amp is under powered it would cause clipping and blow the drivers. If the amp is more powerful and someone does full/high volume the drivers would bottom-out and blow.

What is safer?

odyssey · #8 12-05-08, 11:03 AM

More, More :d

dinyaar · #9 12-05-08, 11:22 AM

Quote:

Originally Posted by Ashish

Dear Friends,

What I meant to ask was what is better for speaker (health), more wattage or less wattage from amp. I understand if the amp is under powered it would cause clipping and blow the drivers. If the amp is more powerful and someone does full/high volume the drivers would bottom-out and blow.

What is safer?

Hi Ashish,
A bigger amp is safer. Ur speakers manual says they can be driven by an amp in the power range of 15 to 150. Now say a 40 w integrated amp may clip if run hard and could damage ur speaker. Be practical and use common sense in system matching. Generally speakers dont just blow unless really abused.
Having said that if someone takes the volume to the maximum u will do damage so u have to be careful. Most budget amps have such high gains that by say 12.O clock volume position u are at close to max output, beyond is pure distortion.Anyway most amps have some sort of protection inbuilt.
As i said earlier buy a high current amp in the power range of 100-120 wpc and it should be more than enough for all ur needs.
Regards

Ashish · #10 12-05-08, 11:51 AM

Thanks Odyssey, thanks Dinyaar,

Well by now you people must have realised that I am a rookie in the world of HiFi asking basic fundamental questions

.
Regarding the specs details of my speakers (MS 906i FS) ,
 Sensitivity 90 db
 Impedance 4-8Ω
For Amps I am considering CA Azur 540A (Vr 2) Or CA Azur 640A (Vr 2)
 think they are solid state (can you confirm please, by looking at their specs)
 Current - what does it mean :
o Slew rate? For 540A it is > 30V/uS, and for 640A it is = 30V/uS, or
o Does it mean Line? - 330mV for both or
o Power output? For 540A it is 60 watts into 8 Ohms & 90 watts into 4 Ohms, for 640A it is 75 watts into 8 Ohms & 120 watts into 4 Ohms.

Looks like I should go for 640A, right?