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Power supply VA rating and how much is really needed

I have a general question. Two actually.

How much capacity of a power supply is needed to allow for each channel in a multi channel amplifier feeding demanding speakers preferred? 

Is 300VA-400VA per channel enough?  Will less be detrimental to performance and SQ? Is more always better?

What are ideal specs for a multichannel ( or stereo amplifier ) that will provide a pleasant experience.  Not looking for the 'best' of the best... but for a decent amp... what are specs that I should be focused upon?

I realize SQ is important, but specs play a role in narrowing down the list I have put together.
--

Second question:

How much output current capacity is need/required/preferred to drive speakers adequately?  And how to calculate the output if the spec isn't given.  I tried google, sadly I didn't find the formula I was looking for.

Is for example 40A enough? Is 30A?  

What factors need I consider in figuring out what spec matters most?

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My speakers consist of B&W CDM 9NTs with matching center channel.  

Contenders:

Emotiva XPS 5ch
Monoprice 5-7ch 
Rotel RMB1585
Odyssey Stratos 2ch and adding emotiva basX 5-7ch or something like it ... possibly used market parasound, rotel, acurus, etc for surround duties.


Not sure which of these actually have the best specs that translates in to best bang for the buck purchase to provide sweet midrange, tight punchy controlled bass, and nice sweet highs but not to bright.

I know the Rotel is highly recommended based on blending well with my speakers - but when do specs trump sound? Or does it?

I am removing power cords, fuses etc from the equation for a moment.

lightfighter2018

Showing 4 responses by lightfighter2018

lightfighter2018 OP
75 posts
 
@erik_squires 

Just to clarify. And maybe I worded it unclear.  

I was asking about capacity of power supply. Ex: A 2 ch amp with a Tor PS of 1100VA ... you are saying it translates into 550w per ch? That doesn't makes sense if amp is rated at 8Ohms at 200wpc... 

If it was unclear - I want to know how much power a PS should have to drive difficult speakers... and how much output in current is suggested... 45A etc?

Sorry if there was confusion.

lightfighter2018 OP
75 posts
 
Got it.

Thx. I am not trying to drive in circles - but just for kicks --

So - question -- all things being equal in the audio world -- I know they are not, but given the following -- is one better than the other in dynamics, , sq simply because one has more power from the supply available? And will I sonically experience a difference in SQ? I know MP amps are not high end - but I am trying to wrap my head around specs in general.

1. monoprice ati clone 2ch -- Toroidal Transformers 1 (800VA)
2. monoprice ati clone 3ch -- Toroidal Transformers 1 (1,025VA)

I am only using the above amp as an example because MP happens to have a full spec sheet, unlike the others I am looking at.

Although I don’t see the spec that Odyssey, Rotel, or Parasound lists on their spec sheets which is Current Delivery.

So where does the current in ’amperage’ output delivery come into play here? As I understand it - more current output -- better dynamics, better sq... and from what I can gather - better amps -- have higher current output, which is one of many reasons they sound better.


Odyssey Stratos ( since it is one I am considering) lists the spec :
Not trying to be a dumbass - just trying to ’get it’.




lightfighter2018 OP
75 posts
 
@erik_squires 

Thanks I will read up on what Nelson Pass has written.

Based on what you have stated. And your knowledge base - 

given a budget of approx max $2k-$3k... 

all things being equal ... which do you think is a better amp based on specs? And which do you think would be a good fit for B&W speakers?

monoprice 1800/2007 ati clone?
odyssey stratos 2 or 3 ch or khartago version
rotel rmb-1585
emotiva xpa5 
outlaw 7700



I realize that how things sound is the end game -- and these are not top tier products - as they are all midfi at best... but I don't have the budget for the likes of Pass, Levinson, etc... 

Am I missing any contenders in the amplifier space that I should consider?


 



lightfighter2018 OP
75 posts
 
Thanks for the input.  Have learned much already.
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