Is the genral rule the smaller the room the less powerfull the AMP you need ?

jamieuk23 · 12 Jul 2007 at 21:52

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Ok I no most people will say more power is better but would buying a powerful amp in a smallish room just be a waist of money ?

I am going to convert my garage which will be 16ft x 10ft in to a cinema room and I will buy one of the new Onkyo amps once most of the work is complete.

Now I am the type of guy were I feel like I am losing out if I just don't buy the most powerful amp out of this range which would be the 875 or 905, and will no doubt be thinking all the time that I should have got more power!!

But am I right in thinking that it would just be a waist of money to buy such a powerful amp in such a small room and the 605 version would be more than anuff ?

I no a lot comes down to the speakers you are using as well... here are my speakers specs - Hopefully you will agree that I don't need the most powerfullest amp and I can buy sensibly

surround sound speakers

Type - Floorstanding speaker canton CD 100
Engineering Principle - 2½-way Bass reflex system
Nom. /Music power handling - 70 / 120 watts
SPL (1 watt/1m) - 86.5 db (1 W, 1 m)
Frequency response - 50...25.000 Hz
Crossover frequency - 400 / 3.500 Hz
Woofer - 2 x 80 mm (3''), aluminum
Midrange - 2 x 80 mm (3''), aluminum
Tweeter - 1 x 15 mm (1''), aluminum

front and centre speakers canton Cd 360F

Type - Flat speaker
Engineering Principle - 2½-way closed system
Nom. /Music power handling - 110 / 170 watts
SPL (1 watt/1m) - 87.5 db (1 W, 1 m)
Frequency response - 33...30.000 Hz
Crossover frequency - 400 / 3.300 Hz
Woofer - 2 x 110 mm (4''), aluminum
Midrange - 2 x 110 mm (4''), aluminum
Tweeter - 1 x 25 mm (1''), aluminum
Nominal impedance - 4...8 ohms
Dimensions (WxHxD) - 12.5 x 60 x 10 cm
(4.9'' x 23.6'' x 3.9'')

Shimmyhill · 12 Jul 2007 at 22:32

Power often comes via greater efficiency.

Having a headline higher power figure can be misleading, it it is done with cheap amps, psus etc then it is not worth it. If it comes because you have better Amps , psus etc then it is worth it. It can also mean you can drive the amp harder before the sound drops off or you get distortion.

Of course you can get an amp with vastly lower power figures but much better sound clarity etc !

marl · 13 Jul 2007 at 20:16

Like matching an engine to a car you have to make sure your chosen amp can drive your loudspeakers to a satisfactory volume level. The size of the room doesn't really come into it unless there's a mismatch with the speakers.

There is no direct correlation between power and sound quality and it makes no sense to get obsessed with power output figures. I'd say that on most occasions you'll be listening at modest volume levels anyway!

In any case, how loud a system will go will depend as much upon how easy to drive the speakers are as they do the power output of an amp!

I also remember reading the product literature of an integrated amp i was thinking of buying. It came in 2 power versions, and from what i can remember, apart from price, the only other difference was that the higher powered version had more capacitors, a bigger transformer and a bigger case. Sonically it was on a par, it just had the ability to drive less efficient speakers.

squiffy · 13 Jul 2007 at 20:23

Those speakers are quite unefficient, therefore the power will come in handy. If I recall, for every 3dB you'll need x2 the power output to get the same dB level.

Also there's more to it than just power, you also have current delivery. Ie for 4Ohm speakers you need a amplifier with a hefty power supply.

It doesn't harm anything if you overspec the power output. Ie Krell poweramps with budget speakers. But it'll cause problems with unefficient, hard to drive speakers with a budget poweramp.

I have around 3KW of RMS power, with amps that can drive 2Ohm loads, in a small room. Am I using close to that? No. But will my amps run into clipping? No way.

Onkyo poweramps are capable of driving low loads, however I don't like there testing method (6Ohm DIN)

jamieuk23 · 13 Jul 2007 at 21:16

and I just thought it was as easy of just choosing a AMP and buying it

As you guys seem to be on the ball ! what Onkyo Amp should I buy out of these specs from looking at the info of my speakers above

Onkyo TX-SR605
Audio Features
• 140 W/Ch Minimum into 6 Ω, 1 kHz, IEC (1 Channel Driven)
• DTS®-ES™ Discrete/Matrix, DTS® Neo:6, DTS® 96/24, Dolby® Digital EX™, Dolby® Pro Logic IIx
• H.C.P.S. (High Current Power Supply) Massive High Power Transformer
• 192 kHz/24-Bit DACs for All Channels
• WRAT (Wide Range Amplifier Technology)
• Advanced 32-Bit Processing DSP Chip
• 5 Digital Inputs (3 Optical/2 Coaxial)
• Subwoofer Pre Out
• CinemaFILTER™
• A-Form Listening Mode Memory
• Optimum Gain Volume Circuitry
• Non-Scaling Configuration
• Tone Control (Bass/Treble) for Front L/R Channels
• Color-Coded 7.1-Multichannel Inputs
• Independent Crossover Adjustment for F/C/S/SB (40/50/60/80/100/120/150/200 Hz)
• Double Bass Function

Onkyo TX-SR705
160 W/Ch, Continuous 6 Ω , 1 kHz, 1 Channel Driven, IEC
• THX Select2™ Certified (with THX Processing)
• DTS-HD® Master Audio, DTS-HD® High-Resolution Audio, Dolby® True HD, Dolby Digital Plus Decoding
• H.C.P.S. (High Current Power Supply) Massive High Power Transformer
• 192 kHz/24-Bit DACs for All Channels
• HDMI (v.1 .3a) Audio and Video Processing
• HDMI Video Upconversion
• Component Video Upconversion
• HDTV-Capable HDMI (3 Inputs and 1 Output) and Component Video (50 MHz) Switching (3 Inputs and 1 Output)
• WRAT (‘Wide Range Amplifier Technology)
• Three Advanced TI 32-Bit Processing DSP Chips
• Audyssey Multi EQ XT to Correct Room Acoustic Problems and to Calibrate Speakers
• Neural -THX Surround Technology for Gaming, Movies and Broadcasting
• Powered Zone 2 and Zone 2 Line-Out for Playback in Another Room
• RS232, IR and l2V Trigger Connectivity

Onkyo TX-SR805
AUDIO FEATURES
• 180 W/Ch Minimum into 6Ω, 1 kHz, IEC (1 Channel Driven)
• DTS®-ES™ Discrete/Matrix, DTS®Neo:6, DTS® 96/24,
Dolby® Digital EX™, Dolby® Pro Logic IIx
• H.C.P.S. (High Current Power Supply) Massive High Power Transformer
• WRAT (Wide Range Amplifier Technology)
• 6 Digital Inputs (3 Optical/3 Coaxial) and 1 Optical Output
• A-Form Listening Mode Memory
• Linear Optimum Gain Volume Circuitry
• Non-Scaling Configuration
• Tone Control (Bass/Treble) for All Channels
• Color-Coded 7.1-Multichannel Inputs and Pre Outs
• Independent Crossover Adjustment for F/C/S/SB (40/50/60/70/80/90/100/120/150/200 Hz)
• Double Bass Function

Onkyo TX-SR875
200 W/Ch, Continuous 6Ω , 1 kHz, 1 Channel Driven, IEC
• THX UItra2™ ’ Certified (with THX Processing)
• DTS-HD Master Audio, DTS-HD© High-Resolution Audio, Dolby© TrueHD, Dolby© Digital Plus Decoding
• H.C.P.S. (High Current Power Supply) Massive High Power Transformer
• VLSC (Vector Linear Shaping Circuitry) for All Channels
• 192 kHz/24-Bit Burr Brown DACs (PCM 1796) for All Channels
• HDMI (v.l.3a) Audio and Video Processing
• HQV Reon-VX Video Processing
• HDMI Upscaling and Upconversion (to 1080p )
• Component Video Upconversion
• HDTV-Capable HDMI (4 Inputs and 1 Output) and Component Video (100 MHz) Switching (3 Inputs and I Output)
• Dual Push-Pull Amplifier Design with 3-Stage Inverted Darlington Circuitry
• WRAT (Wide Range Amplifier Technology)
• Three Advanced TI 32-Bit Processing DSP Chips
• Audyssey MuItEQ® XT to Correct Room Acoustic Problems and to Calibrate Speakers