Power Amp Mains Requirements

[AngelEyes]

Hi Chaps,

I have bought a few new toys recently and realise I may have issues with my power requirements.

I have 4 wall sockets and previously had the power hungry items such as the Cinepro and Onkyo on a wall socket and then all the other gear on two 'supermarket' 6 way distribution boards.

I now have 4 more power amps and at east one is going to be reasonably hungry.

Is it safe / sensible to put power amps on these kind of cheap distribution boards or should I invest in something better and if so what?

Or am I simply asking for trouble?

Thanks,

Adam

[Tone-uk]

If the power strip is 13 amps then the maximum wattage possible is 2990 watts @230 volts. (230v x 13amps).

I would add up the total power consumption of each of you components and see what the totals are. I have always kept things at around 2000 watts - don't really know why!!

(Watts/volts = amps and watts/amps = volts)

[AngelEyes]

Ok, that doesn't sound as bad as I thought then, thanks.

Adam

[lbstyling]

a amplifier that has a 400w output per channel doesnt usualy draw anything like 400w when turned up to the max most of the time because of the duty cycle. during the 'dead time' a amplifier charges capacitance banks giving a averaged power consumption from the wall- typically from music this is less than 30% of peak delivery.

in short--no worries

of interest- this is why class A amplifiers generate so much heat, because the transistors draw large amounts of power even when not in use, because they dont switch off inbitween cycles- they use double the energy -this stops switching noise and transient distortions, giving a good square wave in bench tests.

[alexs2]

Originally Posted by lbstyling

a amplifier that has a 400w output per channel doesnt usualy draw anything like 400w when turned up to the max most of the time because of the duty cycle. during the 'dead time' a amplifier charges capacitance banks giving a averaged power consumption from the wall- typically from music this is less than 30% of peak delivery.

in short--no worries

of interest- this is why class A amplifiers generate so much heat, because the transistors draw large amounts of power even when not in use, because they dont switch off inbitween cycles- they use double the energy -this stops switching noise and transient distortions, giving a good square wave in bench tests.

The peak efficiency of most Class A amps is less than 25%,and for a single ended Class A,even less than that.

The end result is that a 100W Class A amp can easily draw over 400W at idle,and obviously this will not rise,until the Class A level is exceeded and the amp enters Class A/B(as with the old Krells and Levinsons).

As an example,my KMAs draw around 500W each,and dissipate around 400W of heat,but at switch on,the current draw is not far short of 13A transiently,when the PSU caps charge initially.

[lbstyling]

Originally Posted by alexs2

The peak efficiency of most Class A amps is less than 25%,and for a single ended Class A,even less than that.

The end result is that a 100W Class A amp can easily draw over 400W at idle,and obviously this will not rise,until the Class A level is exceeded and the amp enters Class A/B(as with the old Krells and Levinsons).

As an example,my KMAs draw around 500W each,and dissipate around 400W of heat,but at switch on,the current draw is not far short of 13A transiently,when the PSU caps charge initially.

this actually agrees with my post.-but- im not talking about a test bench situation, please read it carefully.

[severnsource]

If you're being pedantic the maximum efficiency of a push-pull class A amplifier is 50%, 25% for single ended. That is only into the designed for impedance and in practice will be less owing to various unavoidable voltage drops.

And as there are no commercial amplifiers that are actually class A it is of theoretical interest only.

[paulst10]

Originally Posted by AngelEyes

I now have 4 more power amps and at east one is going to be reasonably hungry.

Do tell more what have you bought ?

[stevefish69]

Originally Posted by alexs2

As an example,my KMAs draw around 500W each,and dissipate around 400W of heat,but at switch on,the current draw is not far short of 13A transiently,when the PSU caps charge initially.

Adam - Have you not noticed your lights dimming when you first fire up the Cinepro until the caps are charged. Once it's it's on, i've never noticed my energy meter go through the roof though and certainly nowhere near its 2400w input as stated on the side

I've personally always tried to get the power amps and Sub's on dedicated sockets but did have my two Parasounds briefly hooked up on a 8 way anti-spike thingy with no problems. This was along with the Plasma, Processor, CDP, EQ1, PS3, Sky HD and XE1. Still never blew the 13amp fuse even at reference.

Have you considered making your own (cheap) distribution panel using a few MK unswitched sockets mounted on a board with some 4mm cable making a mini ring main within. This could either be hooked up direct to the rear of an existing socket, connected using a nice 13amp plug or better still have the two ends of the ring running direct back to a dedicated MCB if near the fuseboard.

[lbstyling]

Originally Posted by severnsource

If you're being pedantic the maximum efficiency of a push-pull class A amplifier is 50%, 25% for single ended. That is only into the designed for impedance and in practice will be less owing to various unavoidable voltage drops.

And as there are no commercial amplifiers that are actually class A it is of theoretical interest only.

my post was structured around duty cycle- ie, if you get transient peaks of 400w, the caps absorb this and average it out, with the actual draw remaining several orders of magnitude less.
most musical information is at 1 or 2 watts at a highish playback level- the rest is all dynamics.

[IWC Dopplel]

Reading other posts and experimenting with dedicated earths I am about to have a dedicated spur to each unit in my cinema room totally seprarate from the rest of the house. Cabling will be 35mm sq to distribution board and 6mm sq 40 amp cable to each unit. Very low impedence, power supply to the units is as important as power supply in them

You will see a picture of the cabling ready for install compared to stock

[Nic Rhodes]

I have a dedicate ring main to a separate distribution board, note ring. I never have any issue wrt to power loading specs (and not 3kw limited for the ring) and have a huge number of devices on local 8 way Belkin distribution blocks (something like 8 of them). More importantly the noise on the mains (even before the Belkin distribution blocks) is VERY VERY low. In fact so low sniffers had to be returned to manufacturers for checking. It makes a difference

[Medrep1]

I have a dedicated spur, going to unswitched M&K sockets.

I recently had an isotek sigma on loan. I found it took away some slight harshness to the top end, which was a good thing, but it really took away the dynamics from the music. This was only really noticeable when using it on the class D amp?

Could the fact that the main power supply was good enough to warrant the isotek unnecessary, to the point of having a negative impact?

[IWC Dopplel]

Originally Posted by Nic Rhodes

I have a dedicate ring main to a separate distribution board, note ring. I never have any issue wrt to power loading specs (and not 3kw limited for the ring) and have a huge number of devices on local 8 way Belkin distribution blocks (something like 8 of them). More importantly the noise on the mains (even before the Belkin distribution blocks) is VERY VERY low. In fact so low sniffers had to be returned to manufacturers for checking. It makes a difference

Nic, those that have done the experiments have found sonic benefits from not operating rings but using separate spurs. But a difficult one to test. This could be from the better earthing potential from spurs.

I will be able to see if a dedicated supply with star earthing to each component and very low impedance makes a big difference. Most domestic mains uses 2.5mm sq cabling I will be using 35 to the board and 6 to each unit with equal length cables.

I have tried a lot of power supply conditioners, transformers and recently spent a weekend with the big Isotek. All conditioners I have tried slug dynamics (I am told this is related to mains impedance) and some do improve the isolation from mains junk. If you have a dedicated mains supply and separate earthing this will be a 'cleaner' solution.

[Medrep1]

I have tried a lot of power supply conditioners, transformers and recently spent a weekend with the big Isotek. All conditioners I have tried slug dynamics (I am told this is related to mains impedance) and some do improve the isolation from mains junk. If you have a dedicated mains supply and separate earthing this will be a 'cleaner' solution.

Interesting. Could this mean then that people are better off spending a few hundred getting a dedicated spur, as opposed to spending silly money on conditioners etc?

Im about to embark on setting up a new listening room in the house, albeit a bit smaller, but I am looking to do the seperate spur again?

I will follow your posts with interest IWC..........