[Niteshade]

Recently, I had a customer write about some confusing speaker reviews (about the same speaker).

Wattage reported for good results ranged from 30 watts to 150 watts per channel. The question: How could such a range sound good?

My answer:

I own a pair of Von Schweikert VR-2 speakers. They are in the
neighborhood of 86db efficient- which is very low. A five watt
amplifier will drive them and actually do very well with several kinds
of music. Many people will ask why others want more wattage.

The limitations of 5 watts on these speakers:
1. Dynamic range reproduction: There is no room for transients or
complex passages
2. Severely limited volume: The speakers can be driven to just below
the optimum  level

The optimum wattage for these speakers is 80 to 100 watts. One of my
high end receivers has a peak reading watt meter. While playing music
at moderate impact levels, I get spikes of up to 40 watts while
listening with an average wattage of 8-10 watts. A high impact
listening session will easily absorb 80 watts when the average power
output is only 20 watts.

Chamber music can be played and sound very good on the VR-2's with a
few watts. However, when Bluegrass, 80's, movies, etc.. are being
played, it is advisable to use considerably more wattage.

It boils down to what an individual listens to and how they want to
hear it. Wattage can have a direct impact on sound quality, as stated
above.

[Guy 13]

Recently, I had a customer write about some confusing speaker reviews (about the same speaker).

Wattage reported for good results ranged from 30 watts to 150 watts per channel. The question: How could such a range sound good?

My answer:

I own a pair of Von Schweikert VR-2 speakers. They are in the
neighborhood of 86db efficient- which is very low. A five watt
amplifier will drive them and actually do very well with several kinds
of music. Many people will ask why others want more wattage.

The limitations of 5 watts on these speakers:
1. Dynamic range reproduction: There is no room for transients or
complex passages
2. Severely limited volume: The speakers can be driven to just below
the optimum  level

The optimum wattage for these speakers is 80 to 100 watts. One of my
high end receivers has a peak reading watt meter. While playing music
at moderate impact levels, I get spikes of up to 40 watts while
listening with an average wattage of 8-10 watts. A high impact
listening session will easily absorb 80 watts when the average power
output is only 20 watts.

Chamber music can be played and sound very good on the VR-2's with a
few watts. However, when Bluegrass, 80's, movies, etc.. are being
played, it is advisable to use considerably more wattage.

It boils down to what an individual listens to and how they want to
hear it. Wattage can have a direct impact on sound quality, as stated
above.

Hi Blair.
Tell me if I am wrong, there are four points to consider when looking for the ideal amount of watts out from an amplifier :
(In random order)
One : Efficiency of speakers?
Two : Room size?
Three : Type of music you listen to?
Four : What level you listen the music?
I have a pair of GR Research V-1 with 97db efficiency, as a test, I was driving them with a Decware SE-84C+ with only 2wpc, my room is huge, with normal level and with low impact music it was enough, however, with high impact music at a little more than normal level, the music lack impact and was running out of breath at times...
I have now a Niteshade Audio model NS-15 with 10 wpc output and it does much better with high impact music, but I am sure if I had a 30 wpc amplifier it would be more than enough, for me anyway.
However, would I go with a 60 to 100 wpc amplifier ?
With 97 db efficient speakers, I don't think it is necessary and even a waste of money. That's my opinion for what it's worth and you are allowed to disagree with me. I even like it when people disagree with me, I don't get upset, I see that as something that will expand my view on the subject.
Guy 13.

[Wind Chaser]

Few people seem to understand that any given speaker has a limit in terms of how much sound pressure it can generate - regardless of how many watts you put into it.  So at some point every speaker begins to compress the dynamics.  When you reach that point, you have enough power.

[Guy 13]

Few people seem to understand that any given speaker has a limit in terms of how much sound pressure it can generate - regardless of how many watts you put into it.  So at some point every speaker begins to compress the dynamics.  When you reach that point, you have enough power.

Hi Wind Chaser.
I agree with you and your point becomes important especially with full range drivers which have lower maximum wattage input (Usually 20 to 30 watts).
Therefore if the amplifier can handle the peak wattage and the driver can't, then what's the use of having a 100 wpc amplifier ?
I (think) my four points are still valid.
Guy 13

[Niteshade]

I do agree in regards to the speaker. Just like an amp, they can be overdriven.

Guy, you are correct. Those are the points on which amps and speakers should be reviewed before purchase. I do not believe you need an amplifier that is any more than 30-40 watts/channel at that sensitivity rating. As you have noticed, even two watts/channel will work.

What are the signs of a system running with too low a wattage amplifier?

The presentation will lack detail and volume. What's supposed to be punchy will be too smooth. Transients will be tied down, especially if the music is complex. Maybe the best single word to describe a low power issue: Faded. It's all kind-of there but blah. 

[Niteshade]

An important note:

If you have enough volume and the music sounds right- then I doubt you need anything more powerful. Other issues can produce a faded image if there is enough power. To pinpoint these problems, it's best to discuss the equipment you have tried and didn't like as well as your present's gear's favorable qualities. I like to think of a sound system as a single unit when reviewing upgrade options. A sound system is everything- including the room.

[JLM]

Blair, this topic brings to mind the old "tube watts" versus "solid state watts" or the relative size of the power supply. 

Years ago I ran a "meaty" 7 wpc amp with 90 dB/w/m full range speakers and got satisfying results in a 2,000 cu. ft. room at moderate spls.  But bumping up to "meaty"  40 watt monoblocks really added "solidty" and dynamics.  And I've heard that 100 - 200 wpc would really help them open up even more even though they are only rated at 27 wpc continous/80 wpc peak.

[firedog]

Of course, then there is the school of thought that says a system should be able to recreate realistic dynamics of listening to a live  symphony orchestra. That means effortless achievement of 105-110db peaks at the listening position.

So for a typical modern pair of speakers with 87db efficiency and sitting about 3m/10ft away, you'd need 25-30dbw of power. You're then talking about 300- 500 wpc of amplifier power.

And before I get flaming responses: if you have more efficient speakers the calculation is obviously different, and if you don't care about hearing realistic dynamics of 105-110 db, then it also is irrelevant.

[Niteshade]

Since volume can be increased or decreased, instead of the need for all that power, what becomes more relevant is how much power you need at the volume you listen at with regards to your listening environment.

I would call this a matter of ratios. Being able to produce accurate peaks is incredibly important. With low-watt playback, these peaks should be reproduced relative to the average power being produced. For example, my average listening wattage is 1-5 watts with 92db efficient speakers. Yet, I have noticed improvements going from a 5-10 watt amp to a 60-100 watt amp. The small amp did an admirable job- nearly perfect, but I noticed an increase in richness and accuracy of instrument placement (sound stage) with more power. I still very much like low power amps (5-10 watts) because they offer so much for their price and can come VERY close to their big brothers in performance. Not all low power amps are inexpensive- so it's wise not to spend allot of money when the physics of low wattage playback issues remain for any low-watt amp. You can spend ALLOT of money pushing the envelope of low-watt performance and many will be truer in sonics than high-watt models. I do not recommend this route. It is far better to invest in a larger design if it's necessary and make the larger amp perform at its best.

[Guy 13]

Since volume can be increased or decreased, instead of the need for all that power, what becomes more relevant is how much power you need at the volume you listen at with regards to your listening environment.

I would call this a matter of ratios. Being able to produce accurate peaks is incredibly important. With low-watt playback, these peaks should be reproduced relative to the average power being produced. For example, my average listening wattage is 1-5 watts with 92db efficient speakers. Yet, I have noticed improvements going from a 5-10 watt amp to a 60-100 watt amp. The small amp did an admirable job- nearly perfect, but I noticed an increase in richness and accuracy of instrument placement (sound stage) with more power. I still very much like low power amps (5-10 watts) because they offer so much for their price and can come VERY close to their big brothers in performance. Not all low power amps are inexpensive- so it's wise not to spend allot of money when the physics of low wattage playback issues remain for any low-watt amp. You can spend ALLOT of money pushing the envelope of low-watt performance and many will be truer in sonics than high-watt models. I do not recommend this route. It is far better to invest in a larger design if it's necessary and make the larger amp perform at its best.

Hi Blair.
Nice write up and good explanation. Thanks.
I am still sceptical about higher wattage amplifier to fill in the peaks with power. However, a NS-30 is on my wish list. After that, maybe I will say : You were right Blair !
Guy 13.
By the way : I will not mate my 97db efficient speakers with a 60 to 100 wpc amplifier. No sir !

[Niteshade]

It is not necessary to use 100+ watts with 97db speakers, but it will work very well. I do it all the time. My Ashley FET 500 war horse works great on my 100db RF-83's as does my QSC USA-850. The QSC sounds much better to me, I admit. Both amps produce well over 100 watts/channel.

I use my NS-60 in my Klipsch system frequently and find it extremely enjoyable. Due to the speaker's efficiency, I have not found any benefit in running over 60 watts per channel because the room is small.

Moral of the story: Never say never. 

[Dave V.]

Appreciated.

[Guy 13]

It is not necessary to use 100+ watts with 97db speakers, but it will work very well. I do it all the time. My Ashley FET 500 war horse works great on my 100db RF-83's as does my QSC USA-850. The QSC sounds much better to me, I admit. Both amps produce well over 100 watts/channel.

I use my NS-60 in my Klipsch system frequently and find it extremely enjoyable. Due to the speaker's efficiency, I have not found any benefit in running over 60 watts per channel because the room is small.

Moral of the story: Never say never. 

Hi Brian.
This morning (In Vietnam) I did a side by side test of the GR Research V-1 and V-2 with my DIY speakers switch box.



I like to switch within a few second from A to B speakers to hear right away the sound difference. It's the way I do it, maybe not your way of doing it.
For the V-1 (97db efficient) the volume control of my MS-15 (10 wpc) was set at 11 o'clock and for the V-2 (93db efficient) I had to crank it up to 12 o'clock. Not much more.
The litening volume was plenty loud to get in trouble with the neighbours...
Therefore, with a 10 wpc amplifier and efficient speakers, not need to have 100wpc + expensive amplifier, however, later on, I will try a 30 wpc NS-30 to see if the sound peaks/burst will be reproduce.
The results of my test on the V-1 vs V-2 will be posted this weekend on GR Research Audi Circle site.
Have a nice day.
Guy 13.