[Mass. Wine Guy]

I'm not a techie, so this seemed like a good circle to post in. How does a low watt amplifier do an adequate job? My limited understanding is that the higher the power, the easier the amp can handle shifts in the dynamic range, like a symphony going suddenly from a soft passage to a full, loud one.

For example, I was looking online at the new Virtue Audio integrated amp with only 30 watts per channel in typical two channel mode. My Bel Canto has 125 watts per channel. If there is not sonic or performance difference, why do they make amps of varying power levels?

[Tyson]

Usually low watt systems have simpler circuits and fewer parts.  Simple (when done well) usually sounds better in my experience.

[Mass. Wine Guy]

What makes a simple circuit simple?

[Tyson]

Usually fewer output devices, less negative feedback, ability to run most or all the watts in Class A instead of Class A-B or Class B.  When you move out of class A you can also have issues with crossover distortion from the output devices. 

Plus, the less $$ you have to spend on the # of parts on the signal portion of the amp, the more you can spend on the power supply - bigger and better caps, better transformers, etc....

One other thing that is not so obvious is that low watt amps tend to be paired with higher efficiency speakers.  And this is important - High eff speakers generally sound better than low eff ones, all other things being equal (which if course, they never are), but you get my point.

To add a bit more, usually the killer of dynamics is low eff speakers.  They usually sacrifice eff in the name of more bass.  In speakers, there's always a trade off.  Size-Efficiency-Bass pick 2   But with typical audiophile speakers, they try to make them small with good bass and it kills efficiency.  But killing efficiency also kills dynamics.  Which people then try to compensate having a dull sounding speaker by throwing a lot of watts at it with a big amp.  And, IMO, a good big amp with good low eff speakers never sounds as good as a well done low watt amp with well done high eff speakers.  It just sounds more lively and realistic.  PARTICULARLY dynamics come off much better.

[Mass. Wine Guy]

One other thing that is not so obvious is that low watt amps tend to be paired with higher efficiency speakers.  And this is important - High eff speakers generally sound better than low eff ones, all other things being equal (which if course, they never are), but you get my point.

SUre. But in what I'd call the typical real world of home systems many people have, the speakers are not very efficient. My Quad bookshelves are something like 87 or 89. How poorly would low powered amps work with such speakers?

[Tyson]

Added a bit more to my reply above.

But, to answer the question - 87 or 89 would sound fine with a low watt amp, until you turn it up a bit or until there's a large dynamic swing.  Then Solid State amps turn nasty when they run out of steam like that.  On the other hand, tube amps handle that type of overload very gracefully.  Which is one reason so many people love tube amps - nice sound and normal listening levels, simple circuits, and graceful overload. 

But the real culprit, IMO is the speakers.  Having a big amp on low eff speakers is just a band-aid solution.

[Mass. Wine Guy]

Thanks, Tyson. These are very good things to keep in mind for whenever I change my speakers.

[Folsom]

Timbre is hard to get with too many signal path componets at low voltage. Large complicated amplifiers can do it, but not many do. I hear lots of things, but the tendancy for a plastic sound is hard to get over. I know a guy with a setup better than damn near anything with how it's functioning, but the lack on timbre in the highs pulls you out of the realness. Substituting a small AB amp with 3 componets (capacitors) for the large constant current monster brings a lot of that realness, but the bass and authority can't keep up (yet).

Low wattage amps that have good avaliable current will do excellent with the right speaker (if amp has decent SNR). But a lot do not. Tube amps usually do well because current is cheap with high voltage. (Rather an excess is the norm because a small capacitor and wire has lots of overall power at high voltage)

You run into trouble when the impedence curves of a speaker exceed the amps ability to correctly drive it due to not enough headroom (power) at high impedence points. The result can be weak, worthlessly bodiless sound. Some class D naturally struggle this way due to design.

[rollo]

The first Watt is the most important Watt. With 100db efficient speakers low wattage is a good thing. For 83db speakers not such a good thing. Then it depends on driver surface. Lots of drivers like my Pipedreams although 95ddb efficient need power. Sounds great with 18W SET amps but with 500W hybrid class "D" no contest.
     Then thee are speakers that thrive on current like Maggies or other panel speakers. The bottom line here is synergy with the amp and speaker.


 SET design is as simple as it gets just not for every speaker.


charles

[Tyson]

One other thing to keep in mind - 2 way speakers almost always are going to have the problems mentioned above.  Because a 2 way capable of both bass and high efficiency is going to require a 10 or 12 inch mid-bass in a large box. 

It gets interesting with 3 way speakers, however.  There are 2 ways to add that 3rd driver (woofer), either passively or actively.  Passive 3 ways are even worse than 2 ways, because usually the bass woofer is the lowest efficiency driver of the whole bunch, and the mid/tweeter have to be padded down to match the bass woofer.  Terrible solution!

On the other hand, a self-powered bass section allows you to add bass with zero padding or efficiency loss, because you simply turn up the bass woofer amp up till it matches the efficiency of the mid/tweeter combo.  AND you avoid having huge honking coils and caps in the full signal path that is absolutely unavoidable in 3 way fully passive speakers.  Large caps and coils KILL resolution and dynamics, so best to avoid it if possible. 

[Mass. Wine Guy]

Wow, Salis. Much of what you said is way over my head. But I will say that to my budding audiophile ears my Bel Canto D class integrated sounds very good, clear and smooth.

[rollo]

I'm not a techie, so this seemed like a good circle to post in. How does a low watt amplifier do an adequate job? My limited understanding is that the higher the power, the easier the amp can handle shifts in the dynamic range, like a symphony going suddenly from a soft passage to a full, loud one.

For example, I was looking online at the new Virtue Audio integrated amp with only 30 watts per channel in typical two channel mode. My Bel Canto has 125 watts per channel. If there is not sonic or performance difference, why do they make amps of varying power levels?

  With what speaker BTW ?


charles

[sebrof]

What makes a simple circuit simple?

An example of a simple circuit is the 2A3 SET amp I built and use. It has 6 components in the signal path: Input selector, volume, 6C6 pentode, coupling capacitor, 2A3 triode, output transformer. Even a simple push pull tube circuit will have more, and I'd venture to say your Bel Canto has many more.

I'm not really suggesting this means it's better, but it does seem to work better for me personally.

[Mass. Wine Guy]

I'm sure not against trying simpler components. I have Quad 12L speakers.

[JLM]

Agree that low wattage amps tend to sound better because they can be simpler.  Besides being simpler they can use better components for the same price.  Keep in mind that distortion in tubes goes up the harder they're pushed but solid state tend to distort less (assuming you're already in A/B circuit mode) as you approach their rated power output.  Solid state's saving grace is that they typically are designed to run in class A (again a simple design) at low power ratings where most of our listening is done.

But disagree that high efficiency speakers sound better than lower efficiency.  Sure they're more dynamic but they also tend to be more colored (not tonally accurate), they tend to give up deep bass in order to be more efficient (as eluded to above), and they can reveal all the warts (particularly grounding issues) of your system.  Perhaps the issue here is semantics.  I consider an ideal speaker efficiency to be around 93 dB/w/m.

Yes for the best imaging/detail you need enough power to provide a commanding grip on the speakers.  IMO that means being capable of reaching at least 105 dB (even if you don't listen that loud).  With 93 dB/w/m speakers that translates into 20 wpc which unfortunately is beyond typical SET outputs.  So perhaps the best solution is class A solid state amps (which tend to be large, run hot, and are inefficient) or make a compromise in grip, efficiency, or amplifier circuit simplicity. 

[Tyson]

JLM,
I agree for the most part.  Best efficiency range is between about 93db and 100db.  Any less than that and you tend to lose snap and dyanmics, any more than that and the noise issues will drive you insane. 

Disagree about the more efficient drivers being more colored.  I find the opposite, lower eff drivers are more colored in the sense that they tend to sound too dark.  Well done HE drivers tend to be more of an open window on the recording.  Of course, poorly done HE drivers can sound honky and shouty, which I cannot stand. 

Also, with 93db speakers it's 20 watts, with 96db it's only 10, and with 99db it's only 5.  At the end of the day it's very much about the speaker-amp combo.  Having said all that, I use 25 watt First Watt amps running fully class A and a very, very simple circuit.  They are one of the very few SS amps that let me put my tube amps in the closet.  I run my setup fully active, with an electronic crossover before the amps and no passive parts after them.  My tweeter is 106db, my mids are 95db, and the bass woofers don't matter because I use a 1000 watt Crown amp on them   I wish I could have kept the tubes, but they are way noisier than the First Watt amps and having low noise matters in high eff systems. 

Anyway, not really arguing here, just posting some observations...

[Freo-1]

With the right speakers, low wattage amps can sound magical.  One of the most dynamic systems I ever heard was a pair of modified Klipschorns (104 db at 1 watt!) connected to a high quality SET.  As Paul Klipsch was fond of saying:  "What this country needs is a good 5 watt amplifier!".  In short, a good SET does lees to harm/modify the signal. 

One does need sensitive speakers to make low wattage amps work, and getting sensitive speakers that are neutral is no easy task.


I am a big fan of the First Watt M2.  25 watts with a very simple passive gain device. 

My experience with speakers is that the most neutral more often are of lower efficiency, such as ATC.  I also find them to be very dynamic.  Most higher efficiency are not very neutral, and I think plots will back this up. It really is about synergy.   

[Folsom]

Use appealing opinions, but use your ears for the ultimate test.

How's that for simple?

[Guy 13]

Use appealing opinions, but use your ears for the ultimate test.

How's that for simple?

Hi all Audio Circle members.
That's simple enough for me.
From the early age of 18 until to now,
I had a zillion (I know, that's a lot) different audio set up
and the one system that is giving me the most satisfaction for what I paid,
is my system you can see in my gallery.
Far from being the most powerful with it's two wpc.
Far from being the most expensive.
(I had a Naim set up that I have paid 15,000$ 30 years ago,)
Far from being to most beautifull looking.
But simple and efficient and good sound.
That's my last system before I kick the bucket in about 30 years from now,
unless I get run over tomorrow by a 40 tons Vietnamese truck.

Audio should be simple.

Guy 13

[Mass. Wine Guy]

Just curious, then. What are some efficient bookshelf speakers that also sound good?