[RolyG]


I have just bought a Cambridge 751R Home Theatre Receiver (170W RMS per channel, into 8 ohms (two channels driven) 120W RMS per channel, into 8 ohms (all 7 channels driven)  Cambridge752BD, Focal 926 (f), Focal 906 (r), Focal 900 (c) and a REL T9 Sub-woofer. 

 

I really like to play music loud and want to know a couple of things:1

1. Would a Power Amp make a difference to my system?

2. Is the affect different having a Power Amp operating at say 25% power, versus the HTR operating at 75%?

3. If the answer is yes to a Power Amp which on would best compliment what I have?

 

Thanks in advance for your help

 

Rowland

 

[fatbottom]

You don't need a power amplifier however most av amplifiers struggle driving hard to drive. Your speakers are easy to drive and fairly high sensivity. You could consider a 3 channel power amplifier for left, right and center.


I'm a advocate for pre-power I think once you go over a certain quality of components should go av pre-power.

 

[arnyk]



Quote:
Originally Posted by RolyG  /t/1517752/do-i-need-a-power-amp#post_24355753


I have just bought a Cambridge 751R Home Theatre Receiver (170W RMS per channel, into 8 ohms (two channels driven) 120W RMS per channel, into 8 ohms (all 7 channels driven)  Cambridge752BD, Focal 926 (f), Focal 906 (r), Focal 900 (c) and a REL T9 Sub-woofer. 


I really like to play music loud and want to know a couple of things:1

1. Would a Power Amp make a difference to my system?

2. Is the affect different having a Power Amp operating at say 25% power, versus the HTR operating at 75%?

3. If the answer is yes to a Power Amp which on would best compliment what I have?


Thanks in advance for your help

I wish people would read statements like "I really like to play music loud" and then be asked to comment on amplifier power requirements. IOW, the shoe on the other foot.


I really have a sweet tooth. How much sugar should my wife put in her next batch of chocolate chip cookies? Its essentially the same question and just as easy to answer with the information given.


If you want a sensible answer to questions like this, buy a SPL meter, make someSPL measurements from your listening location and then share those! It is possible to estimate power needs with that kind of information. No exact answer still, but at least a Scientific Wild A$$ Guess!


SPL meters are dirt cheap and easy enough to use.

http://www.ebay.com/itm/8928-Decibel-Meter-Digital-Accurate-Sound-noise-pressure-Level-tester-40-130-db-/271167212819

 

[jontyrees]

...or you could just give a reasonable answer like - try it first on just the Cambridge, and see if you think you need it to be louder.

 

[afrogt]

Arny is right though.


People say " I like to play my music loud with no qualifications". How loud is loud? One person's loud is another person's medium volume. Its such a vague question that its impossible to answer. No room size is given either.


Also as to what amp would be recommended? Without a budget it is impossible to make a recommendation.


At least a SPL meter will give an indication of what db range the OP likes to listen to his system.



A simple answer would be to use the system as is and turn it up to the desired volume. If the speakers are distorting/clipping then the volume is too high. An external amp may then help. But still w/o a budget its hard to say what amp to buy.


If those specs are correct for the Cambridge 751R then that should be plenty of power for most people. But then again we have no idea what the OP considers loud. That's where a SPL meter will help.

 

[RolyG]


Thanks for posting a reply, as you can see from my poorly qualified post I'm pretty new at this. The system sounds fantastic and copes well at fairly high volumes (75% whatever that is in real terms). What I was trying to ascertain, I think was clarification on what causes speaker distortion/clipping. Is this due to the speaker maxing out, or the degradation of the input i.e is it similar to driving a car flat out with a small engine howling it's guts out, versus dropping in a bigger engine with smoother, quieter extra power?  

 

[RolyG]


You also asked about the room, well it a pretty big room, that sits on top of a triple garage and has a sarked ceiling (Approx: 16m x 7m x 4m)

 

[JHAz]

speakers distort. amps distort. usually speakers distort first. Ohm's law guarantees that, in our universe, at any given volume level (voltage gain) the amp cannot deliver more power toany given speaker regardless of how much it has in reserve. It's a physical law of our universe.


until you reach the point that the more powerful amp's inherent noise (hiss) becomes audible, generally an amp that is specified at higher power (assuming similarly-derived specifications) will have lower distortion+noise at any given power leve. BUt once the distortion is below audibility, "more inaudible" may be psychologically comforting but will, by definition, make no audible difference.

 

[NK215]

You should go in here:

http://myhometheater.homestead.com/splcalculator.html


and see if you need an amp to get to the spl that you want.


I don't know how to describe it but in my system, the external amp (earthquake cinenova) made a different. My speakers are 4 ohm with a lousy 88db efficiency so my receiver needs all the help it can get. I don't play music or movie loud however. The different I notice is in the sound of rain, broken glass or the musical triangle. With the amp, the sound is so clear and distinctive that it sends chill down my spine - each of the rain drop or the glass pieces has a distinct sound. Without the amp, I still hear rain but it not each drop individually.


It's a nice to have but I wouldn't pay 2K for that experience. I would pay $2K however if my receiver shut off due to over load (which it did when driving the speaker a few time before I got the amp). Back then, it was a HK435 so it's not that powerful. Over the years, I changed receivers but the amp stays.

 

[arnyk]



Quote:
Originally Posted by RolyG  /t/1517752/do-i-need-a-power-amp#post_24357649


You also asked about the room, well it a pretty big room, that sits on top of a triple garage and has a sarked ceiling (Approx: 16m x 7m x 4m)

Room size matters more for subwoofers because their non directional bass tends to fill the room.


Not so with the other speakers - the distance between you and the speaker(s) is more relevant.

 

[arnyk]



Quote:
Originally Posted by jontyrees  /t/1517752/do-i-need-a-power-amp#post_24357232


...or you could just give a reasonable answer like - try it first on just the Cambridge, and see if you think you need it to be louder.

I'm always amazed at how much %$!! I get when I recommend people spend $0.25 or more on test equipment that is relevant to their situation!


It seems like the unwritten audiophile law is "Spend $thousands on audio gear, but not one freakin' penny on test equipment".


Now that AVRs pretty universally come with measurement mics it would cost next to nothing to provide a readout of SPL. But I'm sure the marketing guys have done their jobs and know that even the faintest suggestion of this feature would make 99% of all audiophiles hate their products! ;-)

 

[Greenwood Ave]

There are several free SPL meter apps available for the iPhone too. They seem to work pretty well as far as I can tell.