Explain how a speaker moving at a given frequency powered by a small amp is moving slower than one powered by a larger amp.
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Is there any reason why a more powerful amp should sound better?
- Thread starter davidro
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Explain how a speaker moving at a given frequency powered by a small amp is moving slower than one powered by a larger amp.
In a word, no.
Output power capability in itself bears no correlation to how well a non-overdriven amp will sound.
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theprofessor
Well-Known Member
I'm the kind of guy who thinks it is more fun to drive a slow car fast than a fast car slow...
Brett a
~◦●○o0o○●◦~
I would think filtering capacitance would play a big part.
My Shanling integrated is quite high-powered (2X200W RMS / 8 ohms or 2×320W RMS / 4ohms) But I think it's the 80,000µF of filtering capacitance and independent power transformers for left & right channels that allow it to effortlessly push the echoes of Beethoven's 5th around the walls of the concert hall. This detail was not presented in lesser spec'd amps I tried.
I'm not an engineer, so correct me if I am mistaken, but isn't this amp storing a lot of energy in the filtering caps; having it in the ready for sudden/strong transients. Then the channel-specific transformers are well equipped to recharge them rapidly?
And if so, how does this aspect of amp functioning relate to rated output? Could a 30 watt amp store and recharge like this?
And isn't this why my lights dim for half a second when I turn it on?
My Shanling integrated is quite high-powered (2X200W RMS / 8 ohms or 2×320W RMS / 4ohms) But I think it's the 80,000µF of filtering capacitance and independent power transformers for left & right channels that allow it to effortlessly push the echoes of Beethoven's 5th around the walls of the concert hall. This detail was not presented in lesser spec'd amps I tried.
I'm not an engineer, so correct me if I am mistaken, but isn't this amp storing a lot of energy in the filtering caps; having it in the ready for sudden/strong transients. Then the channel-specific transformers are well equipped to recharge them rapidly?
And if so, how does this aspect of amp functioning relate to rated output? Could a 30 watt amp store and recharge like this?
And isn't this why my lights dim for half a second when I turn it on?
thedelihaus
Nocturnal transmissions
Best I can offer is the only time I felt a bigger amp of similar design (brand, topology, date of manufacture) was when I ran a set of speakers that demanded more power than I was feeding them. My Thiels, for example, are a demanding speaker.
Other times, with a less demanding speaker, say an old pair of EPI 100s or DCM Timewindows I ran, the lesser amp was, by all unscientific experience, at least equal.
I have seen camps argue both ways on this topic- for the longest time, the recommendation was a smaller amp- that a smaller amp of the same make/model style/topography is a better sounding amp than the bigger brothers.
Other times, with a less demanding speaker, say an old pair of EPI 100s or DCM Timewindows I ran, the lesser amp was, by all unscientific experience, at least equal.
I have seen camps argue both ways on this topic- for the longest time, the recommendation was a smaller amp- that a smaller amp of the same make/model style/topography is a better sounding amp than the bigger brothers.
You nailed it.
Amplifier ratings are moving targets. A 30W amp might be able to deliver a 500W pulse for a millisecond but then its output device would need time to cool. If a 30W output device were run at 500W continuously it would burn up within a few seonds. The reason that a 30W output device can provide much greater power for a few milliseconds is that it takes time for the mass of the output device to heat up. An output device can always put out more than its rated power for a brief period of time. By brief I mean micro or milliseconds. The effect is similar to running your finger through a candle and is called "transient thermal response".
Generally amplifier power is rated at given amount of distortion. For example an amplifier might have 30W @ 0.01% THD. As the distortion is allowed to increase the rated power will also increase up to the thermal limit or clipping limit of the output devices. The harmonic distortion is caused by slew rate limiting.
As with all things there are trade offs. As I have been discussing this issue my assumption has been that system noise is zero. There is a risk that as amp power goes up there will be a decrease in signal to noise ratio (S/N) at low listening levels. A low S/N manifests as more hiss or static at low listening levels.
TerryO
Super Member
Ok, you're changing the rules here. I had assumed the OP's question assumed the amps in question were not driven beyond their limits for the purposes of this discussion. All bets are off in the absence of that premise.
I'm not changing the rules. Transient power spikes use the amplifier's headroom. Headroom is rarely rated but it's always there.
Getting away from the technical explanations, can share an experience as a kid. Was running an integrated amp of about 15w rms/channel, and thought it was pretty good. Later put together all seperates, with a Dynaco ST-400 power amp. Just no going back after this, and still running high powered seperates to this day. Same with car audio. Most factory stereos were only a couple watts/channel. Adding a 50-100 w rms/channel amp, made all the difference in the world.
NumbDiver
Super Member
Absolutely agreed. As long as your statement of 25 watt peaks is an absolute.:yes: As long as things like phase-shift; capacitance and inductance of crossovers and working drivers; room nulls/suckouts, resistance and reactance of cabling, etc. ALL add up to the 25 watt peak. Otherwise, the load the amp actually sees may well be much more difficult than a 25 watt peak signal. If any/all of those factors come into play and pull your PS rails down and keep your PS caps from working as the voltage source they were spec'd as; than a larger amp would help.
But in a lab, using a fixed load I agree 100%. And if your analogy takes every factor into account for the 25 watt peak; than I also agree.
I think the two camps are closer than they think they are. If whatever amp can truly handle whatever load, without brick-walling the power supply (can output dynamic peaks without sagging); any additional power said amp can produce...just sits there doing nothing.
That's why my big Levinson is on notice here, as the biggest hog of potential capital, for something that is largely wasted in how I use it. It was bought before I knew I'd not need an amp of its power. Quads and Harbeths can get by on a lot less, for the same SQ.
EddyR
Well-Known Member
This question comes up over and over and I even asked it myself many years ago on here. I have been playing with speakers and amps for almost 50 years and I have found there is not a easy answer. You all new that.
But here is a test I did in the last week. I have been running a set of 1973 Magnepans MG2's for the last couple of years on three amps. The one amp that sounded the best is a Denon integrated 85 wpc amp. I also tried a Carver receiver 130WPC and a RS STA2500 at 100WPC . A few months ago I picked up a set a Speakerlab's DSA 7's and they sit next to the Magnepans. Last week I brought in my Carver FTM15CB's and ran then in Mono at 280 WPC. I wanted to believe they would sound better powering the Maggie's but they do not. I tried three different preamps but the Carver receiver and the Denon still win. The single FTM15 at 100 WPC is close to the Denon. I must admit that I have not tried these speaker on any of my small amps 30-45 WPC. I consider 85 -100 WPC to be small. One thing that is in my favor with the smaller amps is my room is small and if I was trying to fill a big room with sound then the big amp would be the way to go. I play the Maggie's really loud. I have to be careful not to offend people when they want to hear my funny looking speakers by playing them to loud
Ed
But here is a test I did in the last week. I have been running a set of 1973 Magnepans MG2's for the last couple of years on three amps. The one amp that sounded the best is a Denon integrated 85 wpc amp. I also tried a Carver receiver 130WPC and a RS STA2500 at 100WPC . A few months ago I picked up a set a Speakerlab's DSA 7's and they sit next to the Magnepans. Last week I brought in my Carver FTM15CB's and ran then in Mono at 280 WPC. I wanted to believe they would sound better powering the Maggie's but they do not. I tried three different preamps but the Carver receiver and the Denon still win. The single FTM15 at 100 WPC is close to the Denon. I must admit that I have not tried these speaker on any of my small amps 30-45 WPC. I consider 85 -100 WPC to be small. One thing that is in my favor with the smaller amps is my room is small and if I was trying to fill a big room with sound then the big amp would be the way to go. I play the Maggie's really loud. I have to be careful not to offend people when they want to hear my funny looking speakers by playing them to loud
Ed
TerryO
Super Member
I believe that this example will help point out the problem we're having here:
Take two aircraft, one being a Zeppelin with four 7,000 hp radial engines and the other is a stealth fighter with 17,000 pounds of thrust. Now the pilot of the Zeppelin has near instantaineous reflexes, while the Fighter Pilot needs the Nanotech servo assist to nearly match the first pilot's reaction time. The Zeppelin takes off in the morning with 17 hi-yield thermonuclear bombs while the fighter waits on the ramp loaded with 4th of July fireworks. Neither Pilot has had their morning coffee, although the Zeppelin pilot did eat ham and eggs for breakfast, while the fighter pilot had only a Hi-fiber energy bar.
Given this information, is it possible to infer that one of these pilots will reach "42" before the other?
Take two aircraft, one being a Zeppelin with four 7,000 hp radial engines and the other is a stealth fighter with 17,000 pounds of thrust. Now the pilot of the Zeppelin has near instantaineous reflexes, while the Fighter Pilot needs the Nanotech servo assist to nearly match the first pilot's reaction time. The Zeppelin takes off in the morning with 17 hi-yield thermonuclear bombs while the fighter waits on the ramp loaded with 4th of July fireworks. Neither Pilot has had their morning coffee, although the Zeppelin pilot did eat ham and eggs for breakfast, while the fighter pilot had only a Hi-fiber energy bar.
Given this information, is it possible to infer that one of these pilots will reach "42" before the other?
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Of all the perennial hi-fi myths around, none seems to be more prevalent than the "bigger amp = better sound" tenet.
Massive quantites of power never was, is not nor probably never will be- a prerequisite for great SQ. Some of the most highly regarded amps around are tube SETs of very modest power costing huge $$$.
Speaking for myself, I need only small fraction of a watt for most of my listening with peaks requiring perhaps 1-3 watts. Near-deafening loudness sets in around 10 watts. YMMV as innumerable other variables come into play such as speaker efficiency, room size, preferred listening levels, source material- to name a few.
Massive quantites of power never was, is not nor probably never will be- a prerequisite for great SQ. Some of the most highly regarded amps around are tube SETs of very modest power costing huge $$$.
Speaking for myself, I need only small fraction of a watt for most of my listening with peaks requiring perhaps 1-3 watts. Near-deafening loudness sets in around 10 watts. YMMV as innumerable other variables come into play such as speaker efficiency, room size, preferred listening levels, source material- to name a few.
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whoaru99
Epic Member
A smaller amp inherently does fine with less slew rate, relatively speaking, to accurately reproduce any given wave compared to a larger amp.
Just for example, say the small amp has peak output of 10 volts and the larger amp has peak output of 100 volts, and the wave takes "X" amount of time to reproduce accurately. The smaller amp doesn't have to be nearly as fast because it only has to to 0-10 in "X" time whereas the larger amp has to go 0-100 in that same "X" time.
If we turn down the larger amp such that its peak output is no more than the smaller amp (in this example 10V), then the slew rate requirement for both amps to accurately reproduce any given wave is the same.
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