Workhorse said:
Sorry Kanwar, but SR has NOTHING to do with supply levels. SR has to do with the change of output level in volts per microsecond, and is a function of the used devices, topology, compensation and a lot of other interrelated issues.
A +/- 20V amp can have a SR of 50V/uS and a +/- 100V amp can have a SR of 10V/uS. Go read your books.
Jan Didden
sam9 said:
Dynamic headroom is a relative number saying how much the amp can deliver in peaks above the average output. You can have both high and low power amps with the same headroom.
Higher power amps can handle bigger signal levels of course, but the original question states "low listening levels" so that would take this particular advantage away from the high power amp.
This can only be answered if you know the speaker efficiency, listening levels, biasing of the two amps (A, AB, B) etc. I can probably come up with two amps and a speaker that proves just the opposite.
Jan Didden
Kanwar is right sort of but SR is related to output power and is given by:janneman said:
Which bandwidth and which power, so if you know the desired max power and specified load and also wanted bandwidth you also know the required SR but SR is neither a separate thing nor a quality mark as you want to emphasize, Kanwar.
I'll stick with my original theory that it's the better power supply of a larger amp. It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%). Given the commutation artefacts
due to class AB - spray of harmonics AND the emphasis of these at 6 dB /octave by the typical declining PSRR of a conventional miller compensated design, I'd say I'm right on target.
See attached typical miller comp PSRR HF emphasis.
Cheers,
Greg
due to class AB - spray of harmonics AND the emphasis of these at 6 dB /octave by the typical declining PSRR of a conventional miller compensated design, I'd say I'm right on target.
See attached typical miller comp PSRR HF emphasis.
Cheers,
Greg
Attachments
amplifierguru said:
Big amp does not imply a better power supply.
Big has nothing to do with quality. It is certainly easier to build a better supply for a low power amp than for a big amp. A LCRC (all Cs poly) power supply in a 5 W amp is (likely) better than any caps only power supply regardless of amp size (or cost). And within its power limitations is a fantastic amp.
dave
planet10 said:
You cherry picked - I explained why! Again - It's reasonably to expect a designer to allocate sufficient power supply capacitance to keep ripple low (say 1V) at maximum power, so a high power amplifier will have a higher C by 2 or maybe 3 times AND a lower Z transformer (150VA typ 10% regulation, 500VA typ 3%).
The miller comp lets through this, going up at 6dB/octave -
Attachments
I agree that in some cases it's very noticeable when an amp is not driving a pair of speakers properly, and that is evident even at low listening levels.
Untight bass is there.
But in my oppinion (and in my experience) it is not directly related to the power of the amp.
Several things may make an amp become unstable, and a weak PSU doesn't help either.
Complex crossovers, very capacitive cables, etc. can make even a high power amplifier to sound like a mad cow.
In the end, it's all a matter of sinergy, but even then, some low(er) power amps can drive some difficult speakers beyond believe, while others just throw away the towel.
Untight bass is there.
But in my oppinion (and in my experience) it is not directly related to the power of the amp.
Several things may make an amp become unstable, and a weak PSU doesn't help either.
Complex crossovers, very capacitive cables, etc. can make even a high power amplifier to sound like a mad cow.
In the end, it's all a matter of sinergy, but even then, some low(er) power amps can drive some difficult speakers beyond believe, while others just throw away the towel.
Hi Greg,
I agree with you that a poor power supply will cripple an otherwise good amp. I view the power supply as a subtractive thing as it's quality goes down.
All things considered equal, just changing the voltage, the layout and amplifier design is more important. Some amplifier designs are just better than others. Some of these are higher power.
-Chris
I agree with you that a poor power supply will cripple an otherwise good amp. I view the power supply as a subtractive thing as it's quality goes down.
All things considered equal, just changing the voltage, the layout and amplifier design is more important. Some amplifier designs are just better than others. Some of these are higher power.
-Chris
well
just thinking of the thread starter.
He (she?) hasn't taken part in this discussion from the very beginning.
Also I am a bit suspicious about the topic, actually opposite to this hypothesis is believed, most like low power amps for better and clearer sound.
Isn't it a kind of provocation?
Or test thread to tell wisemen from wiseguys?
Looks like searching for proofs to prove wrong theory....
just thoughts
just thinking of the thread starter.
He (she?) hasn't taken part in this discussion from the very beginning.
Also I am a bit suspicious about the topic, actually opposite to this hypothesis is believed, most like low power amps for better and clearer sound.
Isn't it a kind of provocation?
Or test thread to tell wisemen from wiseguys?
Looks like searching for proofs to prove wrong theory....
just thoughts
peranders said:
i agree with peranders here. My explanation is simpler: higher output means higher voltage swings which in turns means higher SR. so a (compotent) high power amp will have higher SR than a low power equivalent, everythign else being equal.
amplifierguru said:
that is true in general but as we are talking about sound quality at low output levels I doubt power supplies make that big of a difference.
planet10 said:
a big amp is likely to have beefier power supply as it needs to have the capability to deliver more to the load. "Better" or not is subjective. But i would say that statistically bigger amps have beefier and more capable power supplies.
planet10 said:
Hi Dave,
the first issue, the reverse spike thing occurs only during the stage when the voltage over the diode is altering, eg. going below Vf.
The diode take some time to stop conduct in the reverse direction when the voltage is altering over the diode, but with rectified 50/60 Hz this is a none issue when considering a fast diode Trr can be around 20nS or so, during this tiny time the 50/60 Hz sine voltage doesn't change much at all, especially near the peak sine voltage where the reversing is mostly occuring. The event is so slow so there's not much RF energy occuring here.
A small note on snubbers, the above explained effect is where to use the snubber for.
In SMPS it's MUCH more important with low Trr time of the diode because there's slew rates of the switched voltage up to severeal thousands of volts per uS, this is what really causes RF enrgy even up to GHz regions.
The other issue when we talk about the peak current when charging cap's occurs only in the forward conduction mode of the diode and has nothing to do really with the reverse current spike due to Trr of the diode, they are quite different things. Under the forward conduction mode the current peak occuring is quite a slow event too, as the change is quite slow due to the very low mains frequency it's in order of mS(compared to Trr in nS), however harmonics can occur but is certainly not in the RF region but rather more in the audio region I would say, but nevertheless can be of course harmfull.
Hope this explains.
Cheers Michael
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