Hi everybody,
If with a bridge topology at +4A per rail per side at +/- 42V DC Rail is given, the total power dissipation is about 672W.
Let's say it is roughly a little over 400W peak Class A power.
Given a 220mF capacitor bank on each rail, how can I correlate the idle power dissipation at the primary with the power dissipation of the secondary, keeping in consideration that the charging current for the reservoir bank brings brings peak current of 46A at the secondary after rectifier thus peak current of over +/- 22A at the primary (this will significantly increase the RMS current thus power consumption) ?
That would suggest that an amp with less capacitance will idle less power for a same given amount of Class A bias(?!?)
Is this statement true?
If with a bridge topology at +4A per rail per side at +/- 42V DC Rail is given, the total power dissipation is about 672W.
Let's say it is roughly a little over 400W peak Class A power.
Given a 220mF capacitor bank on each rail, how can I correlate the idle power dissipation at the primary with the power dissipation of the secondary, keeping in consideration that the charging current for the reservoir bank brings brings peak current of 46A at the secondary after rectifier thus peak current of over +/- 22A at the primary (this will significantly increase the RMS current thus power consumption) ?
That would suggest that an amp with less capacitance will idle less power for a same given amount of Class A bias(?!?)
Is this statement true?
Hi, I'm pretty sure its not true in any significant sense, rgds, sreten.
I can't follow the argument to arrive at the suggested conclusion.
I can't follow the argument to arrive at the suggested conclusion.
The argument is that if for a given amount of bias you have more capacitance, your peak current to charge this capacitance will be much higher than if you had less capacitance, which will reflect in an higher RMS current at the primary which ultimately translates into a huge amount if idle power.
The XA200.5 consumes roughly 700W idle but yet has 100mF per rail and 3.6A bias, which seems to be a pretty low figure compare to what I measure on my amp.
Maybe going from 100mF to 200mF causes the consumption to go from 700W to 1.2KW.
But then looking at the specs for the XS300 series which boosts twice as much capacitance as the XA, power consumption is still roughly 3 times the power rated power.
Ok then would you mind explain why the 200.5 seems to idle less than what I would expect fo and get from the same bias setting?
nope
I already was idiot few times , trying to help you
now , I like more to be idiot for my own causes
I already was idiot few times , trying to help you
now , I like more to be idiot for my own causes
Ok, did I say same voltage rail? I don't think
You have understood my question well enough.
If you did explain further! But please keep in mind voltage rail very similar.
The culprit is on the AC behavior.
Please explain I very curious!!
nope
I already was idiot few times , trying to help you
now , I like more to be idiot for my own causes
Oh the old zen mode, see u haven't lost your sarcasm ehm?
Well what does it matter?!? You seem to have no shortage of idiotic answers...one more, one less...it's pretty much the same! 😎Let me just laugh a little more plz!!!
well , Physic can became idiotic only in idiotic company ......... 
so , when two of us are combined , even poor Physic is Dodo
however , I know how dumb I am ......... so , now I'll leave you to squeeze someone else ;
unfortunately , I can't take Physic out of thread , with me
so , when two of us are combined , even poor Physic is Dodo
however , I know how dumb I am ......... so , now I'll leave you to squeeze someone else ;
unfortunately , I can't take Physic out of thread , with me
It means you do not understand how the XA200.5 operates.
A regular 200W Class A push-pull amplifier would have a quiescent current level of ~3.5A (<= 400W peak Class A in 8 ohms)
With 10% rail losses added, a minimum dissipation of ~440W.
A balanced/bridged design has twice the rail losses, let's say 20%.
Makes the dissipation ~480W.
Which means that 700W power consumption of the XA200.5 is pretty damn high, instead of ''only''.
(aka the difference of 220W is not all lost in the power supply)
What I am wondering though is, accordingly to the 20% estimated loss of a bridge topology, referring to the stock 200.5 with 3.6A bias, takes to about declared 700W power consumption which should be about 6A at the primary if you are running in America...and roughly 3A if you are in Europe.
However cranking some calculations also supported by measurements, to charge up a load of capacitors brings currents to very high peaks, therefore the IRMS figure at the primary is much larger than the expected 6A....and here is where I get confused because all this extra power must be burnt on the rectifiers.
If somebody could explain this I would really be thankful.
However cranking some calculations also supported by measurements, to charge up a load of capacitors brings currents to very high peaks, therefore the IRMS figure at the primary is much larger than the expected 6A....and here is where I get confused because all this extra power must be burnt on the rectifiers.
If somebody could explain this I would really be thankful.
Also If you can keep the tone down to a nicer tone would be really appreciated as well!...might also help this post to flow in a nicer way!!
It seems most of people on the pass labs forum are bitter for some reason! I start thinking it is pointless to post interesting question on this forum.
Beyond the simplistic first condiscendent answers I get, I notice that most of the time the main point gets missed and lost on stupid useless debates!
This question brings up an interesting point on how big power amp construction it carried on.
If the nature of the question is not understood...instead of giving judgments and/or first hand answers...why don't just ask me for clearer explanation rather than simply assuming that the question is stupid?!
Anyway if anybody has an answer to my original question I would really appreciate it!
😎
The 20% I mentioned is just a number, to make it easy.
The XA200.5 does a max of 58V, which is a little higher than 200W/8.
An important item you seem to have failed to understand is that the XA amps are not regular PP Class A.
The XA200.5 does a max of 58V, which is a little higher than 200W/8.
An important item you seem to have failed to understand is that the XA amps are not regular PP Class A.
Sorry, I don't know if I follow but you let me know if this is not what you ask.
You will have a large load peak when you switch the amp on, corresponding to the large capacitor bank getting charged.
The idle current has nothing to do with this peak. The idle current is what the amp draws from the power supply in a constant way and basically depends on the bias current at which the amp runs.
To soften the capacitor bank peak charging current install any suitable soft start circuit at the transformer/s primary. If this is your concern then this is just the way to solve it, and not reducing the total capacitance value of the bank.
You will have a large load peak when you switch the amp on, corresponding to the large capacitor bank getting charged.
The idle current has nothing to do with this peak. The idle current is what the amp draws from the power supply in a constant way and basically depends on the bias current at which the amp runs.
To soften the capacitor bank peak charging current install any suitable soft start circuit at the transformer/s primary. If this is your concern then this is just the way to solve it, and not reducing the total capacitance value of the bank.
thanks Pablo for your reply. No I wasn't saying that. I have a soft start circuit.
Thanks for your intervention anyway.
I probably need to put some picture to support my question.
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