Why so much Wattage ?

[c_dk]

Nickit, as a new McIntosh owner the doors to a plethora of speaker designs are open to you, but do not get bogged down with speakers and new front end options at the same time.

I do find it interesting how many non McIntosh owners have jumped into this thread that would have generated some interesting responses from the audio veterans who designed the cutting edge transformer winding technics that set the standards for low output amp designs in the early 1950s......boy if this discussion would have happened at a Gow seminar we would have had a very lively dinner discussion that night.

 

[4-2-7]

This is what I know from hands on with quality low or high power amps
Most speakers will sound better at all volume levels with a amp that is larger than the specs of the speakers.

I have found even at low volumes (ie: not using all the power the amp has), bass response improves and thus the whole system/speakers sound better at all volume levels. I would attribute this to having plenty of power for speed and control over the large drivers.

So will the 400w speakers sound better with 400w amp or a 600w amp. Well if the speakers can really out perform the rating then I would rather have the 600w amp. Thats why my JBL L250s sound better with my 500 watt amps than they do with the 400 watt amp I have. The JBLs can handle more than their ratings.

"The REF500S sounded more powerful than the Zen, even when listening at fairly moderate volume, and dynamics and bass had more energy. Treble detailing was superior and it was nice to have the freedom to crank the volume. The Zen squashed dynamics, even at quiet volume, compared with the REF500S."

And that's what I have always said, even repeatedly in this thread.

https://www.cnet.com/news/can-a-2-watt-amp-sound-better-than-a-200-watt-amp/
The REF500S, made in Minnesota, 200 watt Class D amp

Decware Zen Triode SE84C+ 2 Watt amplifier

Zu Essence speakers.

The REF500S exerted greater control over the speakers, and I judged its sound as more accurate overall, so harsh, processed, compressed recordings sound harsh, processed and compressed over the REF500S. The Zen made those recordings sound better by removing the edge, and the compression eased the Zen's workload. The Zen's allure wasn't strictly limited to acoustic tunes; DJ Krush's rich and melodious trip-hop masterpiece "Jaku" unleashed a huge soundstage. Beautiful-sounding Japanese instruments commingled with deep bass beats that went nice and low, and the Zen's 2 watts seemed pretty potent, as long as I kept the volume in the moderate range.

The REF500S was clearly more accurate-sounding than the Zen, and can sound wonderful with a wide variety of speakers. The Zen is more musical, but requires careful matching with highly efficient speakers. There's no clear winner here, but my goal for this review was to present an alternative view: high-power amps don't automatically trump low-power amps.

 

[c_dk]

Just to satisfy the tube guys this pic was sent to me from the Woodstock museum by a friend.

Obviously a old warhorse owned by Hanley sound: just think of how many performances flowed thru it over the decades since it helped light up Woodstock

Even in the age of tubes Mac wasn't afraid of going big!!!

 

[4-2-7]

When I put a 120wpc MC2120 in my system, I got the dynamics, bass and energy I was missing with the 30wpc amp at the same, very moderate, listening levels, so Guttenberg's experience was something I could identify with.

I meant to have this in my post @183

Yes what you are hearing is not imagined, many many people hear the same thing happening. I'v also seen many take a amp like yours and get another one and bridge them into 240 Watt mono blocks.

 

[GChief]

The resulting low-level clipping may not be audibly obvious, but it's there, and it is affecting sound quality.

I would agree with this but also add that I prefer the SQ from my small amp over my 140wpc amp while listening loud (95-100dB). And while it is apples and oranges they are both decent and are probably comparable. Total speculation but I can’t see how a restored, mostly stock ckt 8802 is “better” than my Soundcraftsman or Adcoms I have had in the same system

 

[PanheadXR290]

I'm going to open a can o worms, but with solid-state devices aren't they typically cleaner (less distortion) as they approach saturation? There was a discussion a while ago comparing tubes, which are cleaner toward the lower end of their output capability to SS devices that are cleaner toward the maximum output, maybe I'm remembering this wrong.

You didnt open a can of worms but did bring up a very important point, tube amps are much harder to properly match to a speaker over Solid State amps .

 

[David_NC]

I wonder how much of this happens with sub-10 watt amps and efficient speakers vs multi hundred watt amps and low efficiency speakers.

But potentially the largest effect on sound quality—one that doesn't recede with continued use—occurs as a result of temperature-induced changes in the voice-coil's resistance. As the voice-coil heats up, its resistance increases. This has various ramifications, one of which is that the driver's sensitivity decreases, compounding any decrease resulting from the effect of heat on the magnet. As a result, moving-coil drive-units are inherently prone to thermal compression (also known as power compression). The harder you drive them, the less responsive they become.​

https://www.stereophile.com/reference/1106hot/index.html

I'd take that to mean that a hot voice coil isn't as efficient as a cold one. But how would a VC get hot? Lots of power over time. I'd think this would be worse with woofers on bass-heavy material.

 

[Nickit]

You didn't mention the brand/model of the 30w amp.
Speakers?
What is a very moderate level?

I did. See post #54.

There is a lot different about the three amps I used in my little experiment than just power, so I have no idea if more horsepower is the reason the Mac sounded better. I only reported my experience for whatever it's worth. Like Guttenberg in the review I referenced, the higher power amp sounded better at low volume than the smaller amp at the same level. The dynamics, bass authority and suddenness (or speed) with the bigger amp was more like what I had been hearing from my speakers only when the smaller amp was running at higher levels.

The best way I can put it is the sound quality, or perhaps the character of the sound, at 50-75db was more lively, dynamic and authoritative than it should have been (or at least more than it would have been with my previous amp) at those levels.

Like Doc's DeLorean having to hit 88mph before it crosses a threshold and leaps through time, with the smaller amp my speakers needed to get to a certain spl to cross a sonic threshold into their sweet zone. They crossed that threshold earlier (at a lower level) with the bigger amp. It was like Doc's stainless steel ride making the time leap at 75 instead of 88.

We all twist the volume knob and stop when it sounds good. All I'm saying is I can stop twisting a bit sooner (a development certain others in my household are particularly happy about).

 

[SaturationPt]

Here is my experiment (made me curious):

3 amps, 2 pairs of speakers. (added a 4th amp)

I ran my XRT-20s on 50wpc tubes: lifeless, unlistenable really
On 200wpc SS, much better, dynamics, depth, just more involving. Completely different experience.
Then 450wpc, I think I can hear a difference, but as I'm playing them at reasonable SPL I don't think they really needed the power and it didn't have much impact.

Now the more efficient 2-way ESSs. On 50W sound very good, 200W very good, 450W very good, really no change other than the different character I get from these 3 amps on any speakers. Decided to add a 4th amp (why not?) my little 25wpc tube amp, the XRTs laughed at it, even at very low volume (where there really wasn't any SPL for dynamics anyway).

I've left the house (playing with audio almost made me late for a trip), sitting in my hotel room tonight and I don't know the exac ratings of the ESSs, believe they're 92dB efficient and rated for 300W maximum music power. They clearly (in my opinion and having lived with two pair of them on many types of music and equipment over the years) do NOT require a 300W amplifier to make them sing at levels high enough to make my wife give me that
turn it down look. The McIntosh XRTs OTOH, I don't know what it is (and people here talk about running 600w+ to them) but they seem to require power like my old Acoustat 1+1s to really (yep I'm gonna say it) "open up".

Some speakers are happy with small amounts and due to VC design, overall speaker design, they can take a lot of power and turn it into moving air (like JBL monitors for example) without really changing character. Others maybe need a lot of power to get everything moving, dunno I haven't had them all. I can say that my old EV Senior Centurion IIs were almost able to run straight off of a TT cartridge and sound good (well, maybe a bit of an exaggeration).

My conclusion from my un-scientific experiment? Enough is enough, too much is enough, but not enough just plain sucks.

 

[PanheadXR290]

I need a sticky for this....
One of the main points to consider about amplifier power ratings as it relates to sound pressure levels developed by speakers is dynamic range. No one purchases a MC601 or MC1.2Kw to push a continuous 600 watts or 1200 watts into speakers. What the additional power ratings allow an amplifier to deliver is unclipped and undistorted musical peaks. Nearly all well designed speakers thrive on "clean"power but will fail quickly with clipped output from amplifiers. Reserve output power is essential to accurately reproduce the complex wave forms of music.

Music is not a constant tone and volume is not a constant level unless you are amplifying test tones. Music is a continuous stream of peaks and valleys with an average level that is typically consistent. It is not unusual for momentary peaks in a musical performance to rise above the average level by 10 to 12 decibels. These same peaks are often fleeting but require substantial output power to reproduce without clipping the waveforms. We know that for every 3dB rise of input signal the output power will double. Using this information it is easy to understand why an amplifier with plenty of power becomes necessary. As an example lets say you are enjoying a performance at an average level of 25 watts output and a sudden crash of drums or blast of horns generates a 12dB peak above your average level. 3dB above 25 watts would require 50 watts, 6 dB above 25 watts would require 100 watts, 9dB above 25 watts would require 200 watts, and 12dB above 25 watts would require 400 watts of reserve power in order to faithfully reproduce the peak level of 12dB above your average listening level without clipping the output signal. Knowing this, it doesn't seem like such a stretch to have 400, 500, 600, or even 1200 watts on tap.

Another point to take into consideration is almost all speaker manufacturers measure speaker sensitivity at a distance of 1 meter on axis (39.37 inches) directly in front of the speaker. These measurements are most often taken with the speaker placed inside an anechoic chamber where it is completely silent and there is no reflected sound for the microphone to hear. That's not exactly real world conditions that represent a typical end user. In addition, for each added meter of distance from the initial measurement point the audio level typically drops by 3 decibels. Looking at this another way, picture yourself listening to 96 decibels with one watt of amplifier power while sitting in front of a speaker at a distance of 1 meter. Moving your seat away from the speaker to 4 meters distance without increasing the amplifier output you will now be hearing an 87 decibel sound level. At this 4 meter distance you will need to increase the amplifier output to 8 watts to achieve the same volume level at your ears as was present when you were seated only 1 meter in front of the speaker. Move back 1 additional meter to 5 meters distance from the speaker and the amplifier power requirement will double to 16 watts for a 96 decibel sound pressure level at your ears. Even though a highly efficient speaker that produces 96dB with 1 watt at 1 meter is selected, mating it with an amplifier of 25 watts output can be a detriment or not depending on the distance you place your seat from the speakers and at what sound pressure level you commonly enjoy. Remember this, there needs to be sufficient power reserves (headroom) on tap to reproduce the dynamic differences above average level. If it takes 2 watts to sustain your desired average listening level at your selected seating location, you will still need something on the order of 30+ watts available to handle the dynamic range that is present in many recordings.

Changing the speaker efficiency to 86 decibels at 1 meter with 1 watt the perimeters differ dramatically. If you wish to listen at an average level of 95dB at a distance of 4 meters with this speaker, you will need 64 watts of output power not including reserve powerfor dynamics. To faithfully reproduce a 12 dB peak above 95dB average level with this speaker you will need 1024 watts, something a MC1.2KW amplifier can deliver in stride, as can a MC601 on momentary peaks. Both of these amplifier's power ratings are considered by many to be exorbitant but in fact they are necessary with this particular arrangement.

Both of these scenarios are examples of how speaker sensitivity, listening distance, and amplifier power ratings correlate into delivering satisfying listening experiences. It is clear that having additional amplifier power is an asset to reproducing undistorted, unclipped music, thereby protecting our speakers from the damage caused by inadequate power. One needs to consider speaker sensitivity, listening distance from the speakers, typical average music levels required and necessary headroom before deciding on amplifier output power.

The original 16 ohm Altec A7-8 Voice of the Theater speaker had a sensitivity of 101dB at 3 feet with 1 watt. This is the kind of sensitivity one needs to look for when planning to use low output amplifiers. It is all about the proper mating of amplifier power to speaker sensitivity and the sound pressure levels you wish to achieve at your listening position. These things must be considered to take full advantage of any particular sound system.

I hope it helps you understand the relationship of input versus output power and why high powered amplifiers may be necessary, particularly as it applies to your speaker's sensitivity and your common listening levels.

Your post is spot on,depending on the genre ive seen my Mc-1201 monoblocks running at 600 watts continuous & max the amps out at 4,800 short term peak demand several times with modern classical pieces by Frank Zappa,the G-spot Tornado will show any mismatched amp/speaker combo quickly,id like to add to your factual post by bringing up an issue i havent seen spoken of yet, the issue is the Linearity of a speakers operating range.

Im gonna use a Mcintosh Mc-252 as my example amp as i own 2 & 250 watts is within the " just enough " wattage realm were speaking of ,Manufacturers ratings of wattage & ohms are both Nominal,as long as a 4 ohm speaker stays within 4 ohms 51% of the time its listed as a 4 ohm speaker impedance ,i have 8 ohm & 4 ohm speakers , both speakers impedance swings dropping as low as just below 2 ohms, then climbing above 30 ohms ,the ohm load the amp is being hit with is constantly changing with the various frequencies within a piece of music , if the amp selected isnt able to double or quad down in wattage to follow the speakers impedance swing ,not all frequencies will be accurately reproduced, the music will sound veiled & thin due to a lack of synergy between speaker & Amplifier .

If the amp chosen is capable of producing wattages that only meet a speaker systems nominal wattage and ohm ratings its highly unlikely the amp will be able to send the appropriate wattage to meet the speaker systems ohm swing,very few speakers operate lineraly ,when the " just enough " wattage amp meets a non linear speaker load distortion increases & much of the low end frequencies are not accurately reproduced .

Having an amp capable of providing the speaker system with up to 4 Times the speakers nominal wattage rating all but assures youll be hearing 100% of the spectrum within the piece of music ,anything less assures the speaker cannot perform at its best .

 

[Gibsonian]

Here's same spreadsheet from my earlier post, with 89 dB speakers, which is more typical of what the avg Joe has in his casa. Simply listening at avg SPL of 86 dB using 4 watts avg, your amp will need to supply around 40 watts a side to be able to avoid clipping on moderately dynamic material. And if you want concert level without clipping you will need many many watts, and a very high power handling set of speakers to go with it. As was stated earlier, clipping of the waveform is quite common in our listening. I suppose the loudness wars helps with this, but that built in compression sounds even worse than occasional clipping imo.

 

[c_dk]

Many if not most of the users in this forum do not have any clipping issues as McIntosh amps built since 1976 incorporate their patented Power Guard circuit.

Always in the background as long as you keep the distortion below 1% Mac amps don't clip the waveform, even if you over drive them +10dB.

 

[Gibsonian]

Yep, forgot about that. It doesn't allow the clipping by reducing the power output so it can't. You lose the dynamic range of the music either way, sounds better without clipping though.

 

[4-2-7]

Here's same spreadsheet from my earlier post, with 89 dB speakers, which is more typical of what the avg Joe has in his casa. Simply listening at avg SPL of 86 dB using 4 watts avg, your amp will need to supply around 40 watts a side to be able to avoid clipping on moderately dynamic material.

Yeah, I don't understand why some can't grasp this.

As was stated earlier, clipping of the waveform is quite common in our listening. I suppose the loudness wars helps with this, but that built in compression sounds even worse than occasional clipping imo.

This is why I said what I said below.

That's all, some people listen to a lot of clipping and don't even know it. It might be what they like about a set amp, smooth tube sounding rolled off clipping.

We see it here all the time, someone with a vintage 70s sixty watt receiver and matching it to some 80s-90s speakers that are 92db 250 watt speakers. They would be far better off with 98-100db 50 watt speakers even if they are pretty small book shelf.

 

[spark1]

Yeah, I don't understand why some can't grasp this.

This is why I said what I said below.


We see it here all the time, someone with a vintage 70s sixty watt receiver and matching it to some 80s-90s speakers that are 92db 250 watt speakers. They would be far better off with 98-100db 50 watt speakers even if they are pretty small book shelf.

Not many decent small speakers with that kind of sensitivity. Hoffman's Iron Law and all that.

High quality stand mount speakers are most often in the sub-90dB range.

Power handling is not a very important spec, other than when it limits the ability to achieve desired SPL.

 

[Gibsonian]

True on that. And if the speaker is 98 -100 dB sensitive, you are also giving up the low bass. Iron law again.

 

[fill35u]

I'd take that to mean that a hot voice coil isn't as efficient as a cold one. But how would a VC get hot? Lots of power over time. I'd think this would be worse with woofers on bass-heavy material.

Rule of thumb for power compression is that it starts around 10% of the speaker's rated power. At 50% you've hit diminishing returns, and further power input only heats the voice coil more, increasing its resistance even more, so there's no increase in SPL. Power compression typically robs a few dB off the theoretical long-term output.

How long does power compression take to have effect? Depends on the driver. A heavy 4" diameter overhung voice coil with a high specific heat will obviously have more thermal inertia than the coil in a 1" soft dome tweeter. Somewhere between a second and a minute. Heat transfer to the rest of the structure and the ambient air is inefficient, but inexorable.

Crossover components can get hot from carrying current, too. The heat from the driver can also contribute. The electrical changes from heating of the driver and/or crossover can affect bass alignment, crossover points, and relative driver output levels.

 

[fill35u]

I would attribute this to having plenty of power for speed and control over the large drivers. And then yes when your really pushing the system you don't have clipping issues and still have the speed for the low frequency.

Speakers are driven by changing voltage which causes a changing current which causes a *change* in speed(acceleration) which produces a change in pressure which we perceive as sound. This "speed" issue can be viewed in the frequency domain as frequency response. In other words, if the speaker and amp produces the desired frequency response, "speed" is not an issue. Unless the speaker is incompetently designed, the woofer will be crossed over at a point where its high frequency rolloff doesn't compromise the overall speaker response. "Speed" is not a problem, and it's not a problem for any decent amp at woofer frequencies.

Necessary slew rate is a product of both maximum frequency and output level desired. Problems with slew rate show up in high frequency response and distortion, not woofer frequencies.

Damping factor and power are two completely different things, you can have high DF and low power or vice versa. Or both, or neither. Once you add in speaker cable and crossover network resistance, DF is usually a moot point anyhow. DF is also moot once it's high enough to get frequency response variations below the threshold of audibility, and it doesn't take much DF to get there. Of course, DF varies with frequency as well... But for the sake of this thread, and the mention of "woofer speed", I do think it's good to point out that the flea-watt amps being mentioned typically have such low DF that they can sound noticeably different from typical higher-powered amps. Just don't confuse this with a difference of rated power alone.

If I can push the speaker into distortion prior to and not clip I have enough power for that speaker and I'm not under powering it.

If your amp is on the verge of clipping, but the speaker can take more *and you still aren't as loud as you desire*, then yes you are underpowering it.

You can't really hear clipping until it gets pretty bad, so your listening to inferior music under powering.

This is self-contradictory. If you can't hear something, how does it make the music inferior?

Distortion on the other hand you can hear very quickly and can dial back the volume.

Clipping *is* distortion.

Interestingly, we can overlook a *lot* of THD from loudspeakers. Yes, we notice when things get really bad or there's a mechanical noise or resonance, but it's amazing how much we otherwise can't even detect.

If you want to minimize distortion, seek speakers which minimize excursion. High excursion with linearity is difficult, so if you go that route be prepared for the expense.

 

[GChief]

And my post #170.

I love reading post trying to explain away what many of us do every day, it’s entertaining

 

[opnly bafld]

I did. See post #54.

Model???