I have a good friend who is planning on updating the "electronics" in his 2 channel system. Currenly he has a pair of Sonus Faber Amti's and he is trying to decide between a Halcro stack and a Krell Evolution stack. In each case the dealer is telling him that more powerfull amps will always sound better, regardless of volume, he doesnt have a large room or listen to very loud music. Do you guys agree?

The Sonus Faber factory rep says the opposite, he believes that the Krell Evolution 400 (400w mono blocks) will sound fantastic and that moving up to the 600 or 900 will not improve the sound given listening levels below 100db and that the money saved should be spent on better source equipment. With the monoblock, he is considering the EVO 505 SACD player and the EVO 202 Preamplifier.

The Amati's are 4 ohm speakers and have a sensitivity of 92 db so the Krells would be pumping out 800 watts. The Halcro solution is similar either the DM68 Monoblocks or the DM88 Monobloks with the DM10 preamplifer.

Thanks in advance.

It really depends on if you want 400 horsepower in your Hyundai or 900.

I have a good friend who is planning on updating the "electronics" in his 2 channel system. Currenly he has a pair of Sonus Faber Amti's and he is trying to decide between a Halcro stack and a Krell Evolution stack. In each case the dealer is telling him that more powerfull amps will always sound better, regardless of volume, he doesnt have a large room or listen to very loud music. Do you guys agree?

The Sonus Faber factory rep says the opposite, he believes that the Krell Evolution 400 (400w mono blocks) will sound fantastic and that moving up to the 600 or 900 will not improve the sound given listening levels below 100db and that the money saved should be spent on better source equipment. With the monoblock, he is considering the EVO 505 SACD player and the EVO 202 Preamplifier.
apatel,

There are really TWO questions here - will the more powerful amp sound better, and is
that the best use of scarce resources.

Neither tubes nor transistors used in amplifiers are truly "linear" over their entire range
of operation. If you plot the output vs input characteristic for these devices, they are
not 100% straight lines. Therefore, the smaller the fraction of the amp's capabilities
that you sample; the better. Even a second order curve like a parabola looks linear
if you sample a small enough piece of it. So, all else being equal; the more powerful
amp has an advantage.

However, like all things in audio; there is the law of diminishing returns. I think that is
what the Sonus Faber rep is getting at. Your friend could go for the more powerful amp
and realize a marginal improvement. However, is that the best use of his finite resources?

The question is can your friend get more "bang for the buck" by allocating his money to
some other portion of the audio chain.

There are no simple, and unique answers here. Your friend needs to audition the amps
in question and only he can decide how best to spend his audio dollar. If possible, he
should listen to "equal value" of equipment - the more expensive amp with the cheaper
front end along with the cheaper amp and the more expensive front end - and decide
which allocation of audio funds gives him the better sound.

Again - there's no easy answer in the audio world - you have to do your own homework.

I have a good friend who is planning on updating the "electronics" in his 2 channel system. Currenly he has a pair of Sonus Faber Amti's and he is trying to decide between a Halcro stack and a Krell Evolution stack. In each case the dealer is telling him that more powerfull amps will always sound better, regardless of volume, he doesnt have a large room or listen to very loud music. Do you guys agree?

Ugh. Let me guess, the more powerful amps also cost more :rolleyes:

There is essentially no correlation between power and sound. It has more to do with quality. All my favorite amps have been 30W-50W for some reason.

Ugh. Let me guess, the more powerful amps also cost more :rolleyes:

There is essentially no correlation between power and sound. It has more to do with quality.
John,

Yes - quality is part of it. However, so is power as I explain above; because you sample
a smaller fraction of the active device's operating curve.

Again - practically any curve is linear if you sample a small enough chunk of it.

As usual, there is no ONE "correct" way to achieve linearity. For a given active device;
one can sample a smaller portion of its operating characteristic by making a more powerful amp;
or one can get a more linear active device.

While what Greg says is correct in a fashion... the best sounding system i have ever heard has 18 wpc. and it is plenty loud.

in reality, the theory is that if it is 400 wpc, then the power supply and all the other parts will have no issues doing the 10-20 that is about the max you would ever coax out it. at 12' away with a 90 dB speaker you only need 14 watts (approx) to get back to 90dB. so that 400 watt amp can push 107.8 (average... NOT PEAK!!!)

in reality, big amps are like V-8's (not the drink) everybody likes to talk about how big it is, but a well built 4/6 cylinder can beat the crap out of it in many cases!

before you two start again :D

you are both right.

But johns statement about no correlation of power to quality is bang on. there is a theoretical advantage, but that all falls apart once the thing is built.

While what Greg says is correct in a fashion... the best sounding system i have ever heard has 18 wpc. and it is plenty loud.

Dizzman,

I agree with the above - and we have both heard that system.

The 18 wpc LAMM amplifiers driving that system are designed using the second
method of the two I stated above.

At only 18 wpc; the Lamm ML 2.1 is sampling a bigger fraction of its operating curve
than would a more powerful amplifier with the Wilson speakers in that system.

However, the fact that the Lamm is so linear is due to the linearity of its 6C33C output
tube, its 12AX7s, and the basic design of the amp.

There are no simple, and unique answers here. Your friend needs to audition the amps
in question and only he can decide how best to spend his audio dollar. If possible, he
should listen to "equal value" of equipment - the more expensive amp with the cheaper
front end along with the cheaper amp and the more expensive front end - and decide
which allocation of audio funds gives him the better sound.

Again - there's no easy answer in the audio world - you have to do your own homework.

Very True... Your Friend should conduct a careful audition... I will join the Chorus.. There is no simple answer...

Thank you for all of your replies...in the end it comes down to personal experience...again!

A typical 90 dB efficient home speaker being fed 10W will have heavy, obvious audible distortion. A good 50W amp won't even be straining in the slightest. Drink a 6 pack, you might want more power, but otherwise.......

in the end, design always wins over brute force. and in most cases... design can cost more. in the case of LAMM... MUCH more.

A typical 90 dB efficient home speaker being fed 10W will have heavy, obvious audible distortion. A good 50W amp won't even be straining in the slightest. Drink a 6 pack, you might want more power, but otherwise.......

not to belabour a point, but that can depend on where in the operating range that 10 watts is. not that we find lots of 10 watt amps in anything other than pure audiophelia insanity (first watt anybody? :D)

i always kind of smile and chuckle inside when a person goes on about how much power they have.

I recall when Ob was trying to decide to move from the 600 watt arc amps (which predicated the need for an increase in his home AC system) to the 18 watt LAMM's. morbius and i explaining to him that indeed, he would not run into an issue. And in anything other than REALLY cranking it... he has not run into the tops of those amps.

The 18 wpc LAMM amplifiers driving that system are designed using the second
method of the two I stated above.

At only 18 wpc; the Lamm ML 2.1 is sampling a bigger fraction of its operating curve
than would a more powerful amplifier with the Wilson speakers in that system.

However, the fact that the Lamm is so linear is due to the linearity of its 6C33C output
tube, its 12AX7s, and the basic design of the amp.

I believe you and Dizzman when you say it sounds great, but I do wonder if it would sound better with more power. Assuming 2 channels operating, 10 ft listening distance, and 3dB room reinforcement, you get 104dB with 18 watts and 95dB sensitivity.

From the Musical Fidelity site:

How loud should musical peaks be?

Several years ago, John Atkinson, editor of Stereophile, measured,
from a normal audience position, the peak level produced by a small
symphony orchestra in a concert hall. He measured peaks of 109dB to
110dB. One of the top recording engineers in the world, Tony
Faulkner, regularly measures 113dB to 116dB peaks from large
symphony orchestras. Rock music is even louder. Please understand
that these levels are on musical peaks, and not average continuous
levels.

If a hi-fi system is to be realistic, it should be able to achieve
realistic peak levels at a normal listening position....
it is beyond dispute that the smaller amplifier will be
incapable of ever, under any circumstances, producing a significant
dynamic attack. In our opinion, dynamic attack is vital to the
realistic reproduction of music.

Also, the graph at the bottom of the page 2 of the following:
http://www.baua.de/nn_53260/en/Topics-from-A-to-Z/Noise/pdf/Presentation-Safe-Sound-2007-03.pdf
seems to indicate that measured 25 meters from the front of the stage, the QUIETEST of 70+ measured concerts had peak SPL of about 108dB. The AVERAGE concert had peak SPL of perhaps (eyeballing it) 117dB.

I believe you and Dizzman when you say it sounds great, but I do wonder if it would sound better with more power. Assuming 2 channels operating, 10 ft listening distance, and 3dB room reinforcement, you get 104dB with 18 watts and 95dB sensitivity.
syswei,

I think we already did the experiment. In order to see what effect of more power, we
would need a source that had the same quality as the ML 2.1s; but with just more power.

For a while, OB had the Lamm ML 3s on loan in his system. The ML 3s are the ML 2.1's
bigger brother with 35 watts per channel, if memory serves.

When I heard the ML 3s in OB's system; they were marginally better than the ML 2.1s.

However, in a demonstration of the law of diminishing returns; they weren't THAT much
better to justify the rather substantial increase in price. OB didn't keep the ML 3s.

However, OB did upgrade the Wilsons; and that had an even larger impact on the quality,
as Frantz can well attest.

So yes - more power, of similar quality; did make a difference - but not enough to justify
the cost.

I recall when Ob was trying to decide to move from the 600 watt arc amps (which predicated the need for an increase in his home AC system) to the 18 watt LAMM's. morbius and i explaining to him that indeed, he would not run into an issue. And in anything other than REALLY cranking it... he has not run into the tops of those amps.
Dizzman,

EXACTLY - OB was in a "good spot" here because the Wilson X-2 are so efficient.

For a speaker as efficient as the Wilson X-2s; the 18 wpc Lamms have as much driving
capability on the Wilsons as an amplifier with 10X the power of the Lamms does on a
speaker of 1/10-th the efficiency of the Wilsons.

The efficiency of the Wilsons is what makes possible the use of a relatively low-powered
SET tube amp like the Lamm ML 2.1.

There is essentially no correlation between power and sound.


All my favorite amps have been 30W-50W for some reason.

There's your correlation between power and quality, John.
Your correlation's shape is "concave down parabola"
It looks like it has a peak at 30W-50W.

You are welcome.
:D

Hah! I think I just liked them because they sounded good and were affordable!

Hi

We must keep in mind that the progression is logarithmic.. An 800 Watts amplifier is only 3 dB louder than a 400 Watts... Morbius point remains valid.. Listen carefully to both amplifiers, trying as much as possible to match levels ( an inexpensive Radio Shack SPL < $50 level meter will suffice) and make your decision based on which amp sound you prefer...

Interesting reading guys. Thanks.

What about coupling a good SET amp with the musical fidelity 550k? Best of both worlds?

Interesting reading guys. Thanks.

What about coupling a good SET amp with the musical fidelity 550k? Best of both worlds?

What do you mean to do here.. Are the Amati bi-amp-able?

The musical fidelity 550k supercharger goes between your amp and your speakers and apparently has no sonic signature of its own. It supposedly effectively increases the power of your amplifier. I think stereophile wrote a review on it and said it works as advertised but I've not read any firsthand reviews.

How loud should musical peaks be?

He measured peaks of 109dB to 110dB. One of the top recording engineers in the world, Tony Faulkner, regularly measures 113dB to 116dB peaks from large symphony orchestras. Rock music is even louder. Please understand
that these levels are on musical peaks, and not average continuous
levels.


that is key, PEAK, is different than rated. i would guess ob's amp can hit instantaneous peaks much higher than the 18 watts.

And of course at the same time, average listening is probably more inthe 85-90 range. again... average listening.

The well built amp will not melt when it has to hit a peak... the el-cheaparino... well, it may not be pretty. clipping, etc.

What do you mean to do here.. Are the Amati bi-amp-able?
Frantz,

The Musical Fidelity amps - 550 and now 750 - will take a "high level" signal from a power
amp as their input.

They strive to sound neutral in themselves - so as to preserve whatever sonic signatures
and characteristics are present in the lower powered power amps immediately upstream.

http://stereophile.com/solidpoweramps/907mf/

http://stereophile.com/solidpoweramps/1208mf/

Don't even go there. I've heard it in a very familiar system (ruined a fabulous Shindo sound), not something I would encourage anyone to do. Stereophile was being kind to MF (as usual) :cool:

By the way, there was an interesting read from mid last year by the Spectron designer about peak power. Have a read... Challenges in Faithful Reproduction of Musical Peaks (http://www.enjoythemusic.com/magazine/manufacture/0708/index.html)

The musical fidelity 550k supercharger goes between your amp and your speakers and apparently has no sonic signature of its own. It supposedly effectively increases the power of your amplifier. I think stereophile wrote a review on it and said it works as advertised but I've not read any firsthand reviews.

The Sonus Faber factory rep says the opposite, he believes that the Krell Evolution 400 (400w mono blocks) will sound fantastic and that moving up to the 600 or 900 will not improve the sound given listening levels below 100db

I haven't A/B-ed the EVO 400 vs. 600/900, but based on info from Krell and my own experience w/Krell gear, I would have to disagree w/the Sonus Faber rep.

First: Krell amps (I don't know about others) are not simply scaled versions of the same building block or "unit" circuitry ( e.g., an EVO 400 isn't just a design of two '200 Watt circuits' and the EVO 600 three of those same circuits). The designs of the 400 and 600 have significant differences (if you call Krell they can give you details).

Second: When I moved up from the Krell FBP-350mcx monoblocks to the 450s (which I was told also have non-trivial design differences between them), the differences in the quality and character of the sound ranged from somewhat noticeable to sometimes startling. The 450s revealed the subtle character and texture of instruments and voices and resolved low-level details that were not discernible before, and there was also noticeably more space/air/3D realism and the feeling of the performers "being there" than with the 350s.

But I agree w/most everyone else here that you gotta hear for yourself and then decide...

that is key, PEAK, is different than rated. i would guess ob's amp can hit instantaneous peaks much higher than the 18 watts.

And of course at the same time, average listening is probably more inthe 85-90 range. again... average listening.

The well built amp will not melt when it has to hit a peak... the el-cheaparino... well, it may not be pretty. clipping, etc.

I have no idea what short-term peaks tube amps or that particular amp might be capable of. In the SS world, I think it would be unusual for peak short-term power to be more than 1.5x rated power...such an amp would get you another 1.7dB of volume.