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HOW can bigger amp change sound at lower volume?

SPOautos

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For example, I have inefficient Dahlquist DQ10's that everyone says you need 200wpc amp to get the best sound out of them (irregardless of overall listening volume)....it seems like the overall amp wattage is only relative to overall volume capability. Like a given listening volume (say 60db) both a 100wpc and 250wpc amps can create arent they both sending the same wattage and signals to play at the same volume. It 'seems' like the bigger amp will only have benifit as you turn up volume and exceed the capabilities of 100wpc.

Is it something like the bigger caps and such in the higher watt amp allow it to push the speaker harder eventhough its sending the same wattage to the speaker???

Im confused how a larger amp can change the sound???
 

tonycollinet

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It is to do with the dynamic range of the music. Peaks/crescendos in music can easily be 20dB higher than the "normal" level at which you set the volume.

So if you have inefficient speakers, you may have a normal listening level already at 2x the power of speakers with only 3 dB higher efficiency (3dB is a doubling of power).

Say 2W instead of 1W.

20dB is 100x higher power required for the peaks in the music. So an amp driving the lower efficiency speakers needs to be 200W to avoid clipping the peaks. The amp driving 3db higher sensitivity only needs 100W to avoid clipping in the same circumstances.

This though is at relatively low volumes. To double the perceived volume you need to go typically 10x in power*** - so you can see the problem if you want to listen at higher volumes.

Fact is that most amps will be clipping the peaks at moderate to high volumes - the problem is the clipping is worse with lower efficiency speakers, and MUCH more power is needed to bring it to the same level as with higher efficiency ones (double the power for every 3dB of efficiency reduction)



***Edited to add - we are in the realms of psychoacoustics here - it is imprecise, which is why I've used the word "typically"
 
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SPOautos

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It is to do with the dynamic range of the music. Peaks/crescendos in music can easily be 20dB higher than the "normal" level at which you set the volume.

So if you have inefficient speakers, you may have a normal listening level already at 2x the power of speakers with only 3 dB higher efficiency (3dB is a doubling of power).

Say 2W instead of 1W.

20dB is 100x higher power required for the peaks in the music. So an amp driving the lower efficiency speakers needs to be 200W to avoid clipping the peaks. The amp driving 3db higher sensitivity only needs 100W to avoid clipping in the same circumstances.

This though is at relatively low volumes. To double the perceived volume you need to go typically 10x in power*** - so you can see the problem if you want to listen at higher volumes.

Fact is that most amps will be clipping the peaks at moderate to high volumes - the problem is the clipping is worse with lower efficiency speakers, and MUCH more power is needed to bring it to the same level as with higher efficiency ones (double the power for every 3dB of efficiency reduction)



***Edited to add - we are in the realms of psychoacoustics here - it is imprecise, which is why I've used the word "typically"


Is it mostly the size of the caps and power supply that makes one amp have more dynamic range than another?(given the same overall listening volume).

Sorry if that's a stupid question....I really dont understand the science behind electronics at all.
 

tonycollinet

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Is it mostly the size of the caps that makes one amp have more dynamic range than another?(given the same overall listening volume).
No, it is the peak power it can deliver. Big banks of caps are needed or not to deliver that peak power depending on the architecture of the power supply.

Peak power is generally limited by the power supply voltage. Once the peak of the output wavform exceeds that, they are clipped. (Tops cut off flat). With a linear supply the big banks of capacitors are just needed to stop the PSU voltage drooping as more current is pulled from it.
 
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tonycollinet

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perhaps 40 or 50 years ago, today you would be pretty lucky if that's the case. just something to keep in mind ;).
Is this what I keep reading about as "loudness wars" and/or DR compression in music mastering? What might I expect to see in the dynamic range of typical modern recordings?
 

MediumRare

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I regularly listen at a sustained 20 WPC (although that is pretty loud). My amp is rated at 200 wpc continuous and 400 peaks. I can tell when I turn it up past 20 it’s ever so slightly not quite as clean. To be fair, my speakers dip to 2 ohms, which is why I bought this particular amp.
 

blueone

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No, it is the peak power it can deliver. Big banks of caps are needed or not to deliver that peak power depending on the architecture of the power supply.

Peak power is generally limited by the power supply voltage. Onnce the peak of the output wavform exceeds that, they are clipped. (Tops cut off flat). With a linear supply the big banks of capacitors are just needed to stop the PSU voltage drooping as more current is pulled from it.

This isn't correct, and is an audiophile myth. In a linear power supply the capacitors are used in the rectification stage in the conversion from AC to DC, they are not used to increase power output capability. See section 5.2 of this excellent Rod Elliott white paper, complete with measurements. The huge filter capacitor bank argument is a myth for increasing peak power, but properly rated capacitor banks are required for smooth DC power if the rest of the power supply is capable of very high output.

 
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SPOautos

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So with my inefficient DQ10's if I go from a 135wpc amp too a 250wpc amp it will open up more dynamic range, maybe better bass for instance....even at lower volume levels. Like I typically listen around 55-70dB and my current amp is hitting around 20wpc....so eventhough my current amp still no where near maxed out, a higher watt amp will still sound better at these same volume levels?

So I dont really understand the science of why this is....but that's okay!
 

JayGilb

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This isn't correct, and is an audiophile myth. In a linear power supply the capacitors are used in the rectification stage in the conversion from AC to DC, they are not used to increase power output capability. See section 5.2 of this excellent Rod Elliott white paper, complete with measurements. The huge filter capacitor bank argument is a myth for increasing peak power, but properly rated capacitor banks are required for smooth DC power if the rest of the power supply is capable of very high output.

The caps in the rectification stage are there to stabilize rail voltages for short periods of higher output demand. The more capacitance, the longer they can deliver full rail voltage without clipping signal levels.
 

MediumRare

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This isn't correct, and is an audiophile myth. In a linear power supply the capacitors are used in the rectification stage in the conversion from AC to DC, they are not used to increase power output capability. See section 5.2 of this excellent Rod Elliott white paper, complete with measurements. The huge filter capacitor bank argument is a myth for increasing peak power, but properly rated capacitor banks are required for smooth DC power if the rest of the power supply is capable of very high output.

I like the article, but I think you misread "to stop PSU voltage drooping" as "increasing peaks". Not the same, of course.
 

DVDdoug

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It 'seems' like the bigger amp will only have benifit as you turn up volume and exceed the capabilities of 100wpc.
This is CORRECT! If the lower-power amp isn't clipping there will be no difference.

Also, going from 100 to 250W is +4dB (4dB louder or 4dB more headroom). That's not a whole lot louder...

It kind of annoys me that more amplifiers & receivers don't have (peak) power meters or at least clipping indicators. A clipping indicator is a simple circuit and it would cost them almost nothing. But then they'd sell fewer high-power amps!
 

blueone

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The caps in the rectification stage are there to stabilize rail voltages for short periods of higher output demand. The more capacitance, the longer they can deliver full rail voltage without clipping signal levels.

No, the capacitors are there to "smooth" ripples in the near-DC output of the rectifier.

It is apparently a pernicious myth that the energy in the capacitors somehow act like a battery that is tapped when the output of the power transformer is exceeded.
 

DonH56

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So with my inefficient DQ10's if I go from a 135wpc amp too a 250wpc amp it will open up more dynamic range, maybe better bass for instance....even at lower volume levels. Like I typically listen around 55-70dB and my current amp is hitting around 20wpc....so eventhough my current amp still no where near maxed out, a higher watt amp will still sound better at these same volume levels?

I tend to doubt it, but perceptual bias is a real thing. Going from 135 W to 250 W provides 2.7 dB additional headroom, not a lot in terms of hearing (which is logarithmic), and that only matters if you are starting to clip the amp you have. There may be other factors at play like lower output impedance and such that change the sound slightly but I don't recall DQ10's being all that bad a load. Long, long time since I heard them, natch.
 

blueone

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I like the article, but I think you misread "to stop PSU voltage drooping" as "increasing peaks". Not the same, of course.

I never said the capacitors increased peak output. You are confusing what I said with someone else's post.
 

Spkrdctr

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To the OP, if you are not clipping the signal which you shouldn't be at such low level listening, there will be no difference. Audio marketing theory also known as "snake oil" says buy a bigger amp and it will make a huge difference. Pure 100% BS. What you have is working fine. If you ever decide you need to listen at a much louder volume, then yes, go for a much bigger amp, most likely a Crown with real power. On the engineering side of this topic, yes, they can measure insignificant clipping that is not audible on dynamic peaks, sometimes. But does it matter at that tiny level for a listener? Nope. But if you have speakers that are working perfectly and you hear weird stuff, it may mean you need a large jump in power. Remember as many posted already, a small change in power will not do much at all. The issue is moving from the oscilloscope to a room with an actual listener means that most of what people are concerned about is nothing to be concerned with.
 

tonycollinet

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No, the capacitors are there to "smooth" ripples in the near-DC output of the rectifier.

It is apparently a pernicious myth that the energy in the capacitors somehow act like a battery that is tapped when the output of the power transformer is exceeded.
What do you think is the difference between smoothing ripples, and stabilising voltage.

The capacitors are only charged during the peak of the waveform coming from the transformer. Whenever the AC transformer output voltage is lower than the DC voltage then there is no power going into the capacitors. All the energy going to the amp is being taken out of the capacitors - during which the voltage will reduce. (ie droop) until the AC input to the rectifier exceeds it again. The bigger the capacitors, the less the droop between peaks of the AC input to the rectifier. Whether you call it ripple or droop, the bigger it is, then the less stable the DC is, so they are also stabilising the DC rails.

Here is a convenient picture of what it looks like:

1634916769027.png
 
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abdo123

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not a lot in terms of hearing (which is logarithmic),

How? +10 dB is percieved 'double as loud' so 2.7 dB would be a ~25% increase in perceived loudness. 25% is a lot.

hearing being logarithmic makes dB as a unit very sensitive to increments. 100 dB is 1000 times larger in absolute amount than 1 dB.

Humans typically have very poor comprehension of exponential and / or logarithmic growth.
 

blueone

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What do you think is the difference between smoothing ripples, and stabilising voltage.

The capacitors are only charged during the peak of the waveform coming from the transformer. Whenever the AC transformer output voltage is lower than the DC voltage then there is no power going into the capacitors. All the energy going to the amp is being taken out of the capacitors - during which the voltage will reduce. (eg droop) until the AC input to the rectifier exceeds it again. The bigger the capacitors, the less the droop between peaks of the AC input to the rectifier. Whether you call it ripple or droop, the bigger it is, then the less stable the DC is, so they are also stabilising the DC rails.

Here is a convenient picture of what it looks like:

View attachment 160718

My original post referred to the incorrect notion that the filter capacitors (sometimes called smoothing capacitors) are capable of increasing voltage beyond what the transformer can supply, that they act as a peak power reservoir. I know how smoothing works.
 
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