Low Power or High Power?

Pastor Bill

Context
Currently have NAD 7140 receiver, 40 wpc. Pair of Fried Model Qs...decent efficiency. The NAD can drive to painful levels before you've even used 40 percent of available volume control. This means that only a small portion of the pot is ever used and I don't think that I ever get anywhere near to clipping. Is it better to have an excess of power/wpc in reserve or is it better to have a lower power unit that utilizes more to achieve the same levels? Be patient with me...it's an honest question. My thought is that power in reserve is desirable...but 40 wpc isn't exactly a powerhouse.

I'm sort of developing the "bug" to collect some vintage receivers/integrated amp/tuners combos...but most that I can afford and that please me are in the 12-35 wpc channel range. Would there be any harm in utilizing a lower powered unit?

What sayest thou?

dragon1952

I guess it tends to even out a bit, all other things being equal (build/parts quality, design quality, etc). A lower powered unit with high current can be just as effective as high wattage in reserve,especially with efficient speakers. If you are looking '70's vintage they all seem to be similar to your NAD I think, meaning they usually test more powerful than their rated power and have loads of current.

Sci-fi Polk Guy

Pastor Bill wrote: »

Context
Currently have NAD 7140 receiver, 40 wpc. Pair of Fried Model Qs...decent efficiency. The NAD can drive to painful levels before you've even used 40 percent of available volume control. This means that only a small portion of the pot is ever used and I don't think that I ever get anywhere near to clipping. Is it better to have an excess of power/wpc in reserve or is it better to have a lower power unit that utilizes more to achieve the same levels? Be patient with me...it's an honest question. My thought is that power in reserve is desirable...but 40 wpc isn't exactly a powerhouse.

I'm sort of developing the "bug" to collect some vintage receivers/integrated amp/tuners combos...but most that I can afford and that please me are in the 12-35 wpc channel range. Would there be any harm in utilizing a lower powered unit?

What sayest thou?

Kenwood and Sansui are a couple of brands you might look into. Back in the day, late '70's and early 80's, those two companies powerful receivers with a very warm sound.

BTW, are you still in the ministry or are you retired?

cnh

That NAD has sufficient power for those speakers. They tend to have enormous headroom! And actually have a sound that is not that distant from the "vintage" sound!

As far as vintage receivers. Any Marantz from the 2215 up will do it. Old Pioneer SX-737 will do it.

I highly recommend the Harman Kardon HK 430 (only 25 watts x 2) but will easily compete with anything modern at over 50 watts x 2. Twin transformers, 4 filter caps. 25 lbs+.

I also like the JVC RS-33 which is a 40 watts x 2 but can often be found on the cheap. Dynamic Super A series.

All of the above will "warm" up the Frieds a bit, IMO.

cnh

tonyb

To answer your question, it's better to have more power in reserve especially if you like to crank on it once in a while. Don't simply go by watts ratings, it's current that speakers desire. Watts ratings are no indication of a well built power supply, which is why some vintage stuff in the 20-50 watt area sound better than todays 100 watt receivers.

pitdogg2

Give me sky high wattage with enough current to levitate an aircraft carrier. Even when you only listen at lower volumes I still like to be able to hear the deepest notes with authority.

cnh

Tony is right.

Let's take a ridiculous example.

The Marantz 2215 has 15 watts x 2 @ 8 ohms continuous. Yet it weighs 24.6 lbs.

An entry level Pioneer AVR VSX 522 rated at 100 watts x 5 surround, lol! Weighs a whopping 19.8 lbs. And has a lot more in it than simple stereo processing.

Which do you think is "better built" for two channel performance? I know this is a gross comparison and weight alone is NOT the only factor. But it is ONE factor.

cnh

tonyb

cnh wrote: »

Which do you think is "better built" for two channel performance?

cnh

Well, a 15 year old would say " The pioneer dude, because I can hook up my Ipod and use the app on my phone."

Dennis Gardner

I think you ask a valid question, since many engines and other things we use are built to operate best in its "power band". There are amplifiers that exhibit some of these traits but most amplifiers are built to be very linear in their power application so that they don't change tone as you apply power.

Vintage gear with "loudness" circuits are the exception to this and tend to boost bass and treble at low volume settings and roll off the effects from this circuit as the volume is increased. This allows a full sound to be present even at the lowest levels where most speakers don't produce much bass. Not all brands use this, so some research may be needed. Enjoy your search.

Personally, I prefer to have the extra headroom/power to play it louder than normal without any fear of damage to my gear.

Pastor Bill

Sci-Fi:
I was ordained December 2010. It's been one of the most satisfying and frightening things in which God has led me to participate.

mhardy6647

The volume control setting is reflective of the "taper" of the volume control (dB attenuation per degree of turn, so to speak -- which is nonlinear in virtually all volume controls, by the way, because the dynamic range of our hearing is so wide - ca. 14 orders of magnitude - so audio is, so to speak, "logarithmic"). It also depends upon the gain of the preamp/amp -- it really doesn't mean anything per se, in terms of power (or, really, anything else).

The subject of amplifier power, loudspeaker sensitivity and loudspeaker impedance characteristics is almost astonishingly complex. It's actually rather difficult to paint simple rules of thumb in broad strokes (although it is easy to mix metaphors!) -- even though lots of folks try.

The important parameters:

Amplifier steady state power output capability (both in terms of voltage and current, due to the variability of load impedance with frequency).
Loudspeaker sensitivity (dB of sound pressure level output at a distance of - typically - 1 meter when fed a signal at a steady level - typically 1 Watt/2.83 AC volts into a pure 8 ohm load).
Nominal loudspeaker impedance (since 2.83V is 1 watt into 8 ohms, but it's two watts into 4 ohms)
Loudspeaker impedance curve.
Room size, geometry and composition ("hard"/"soft")
Music preference (rap, opera, Beethoven, bluegrass, "little girl with guitar", etc.)
Listening position.

a few other considerations (less fundamental, IMO, but still on the table)

Amplifier power supply design and/or
amplifier "headroom"
Distortion parameters of the amplifier (THD as a function of output power, intermodulation and other distortion parameters)
Loudspeaker electronic crossover (if any) design complexity

(I'm sure I am forgetting things)

My amplifier is capable of about 3.5 watts per channel at reasonable (between 1 and 10%) levels of harmonic distortion; speakers have a sensitivity of about 104 dB per watt at one meter (two channels in stereo means three more dB SPL, by the way).

I could do controlled demolition with 25 watts and a sine wave generator...

Are the Frieds transmission line loaded? If so, and if their sensitivity is good (let's say 90 dB or better), a good 15 watt amplifier should be delightful. I had a pair of IMF (named for the same guy, Irving M "Bud" Fried, but UK made) SuperCompact IIs that sounded superb with, e.g., push-pull EL84 power - ca. 14 watts per channel).

Trust your ears.

(all just my opinions on the matter, of course)

cnh

That's all true Mark. But all you have to do is tear open a few vintage pieces and take a look at the engineering in there and it almost always conforms to almost all of the parameters you list above (for amps).

Speaker efficiency is also a factor, especially for those flea amps! But I do believe that the Frieds Pastor Bill has are fairly efficient?

As for listening position and room effects. Well those are problems for any amp/speaker combo! And are often very difficult to resolve. That's why many of us have lots of different ROOMS in our houses, lol!

I have yet to hear a speaker that has a 104 db rating. I know they exist, but none have made it this way?

cnh

soundfreak1

The worst thing you can do is "underpower" speakers! Mo power mo better ( CURRENT AND WATTS) as long as its clean power.

CoolJazz

Having the volume pot at only 40% is NOT necessarily indicative of how much power you have available beyond that point. It tells you the level driving it is higher than the designed normal OR that the speaker is that efficient.

Every amp has a specific gain figure. So with some value in, let's say 1 volt, then it makes that amount of gain to the output with the volume control up all the way. So...if you put in 2 volts, then you get to that maximum output point way quicker as you raise the volume pot. You don't get more level when you go beyond that point, it just start clipping the waveform and everything less than that gets louder...until the clipping and it's sharp clipped edge (meaning excessive high frequencies) blows the tweeter.

CJ

PS...several posts since I started typing.

tonyb

Efficiency ratings too are only part of the equation. Mine are 95 efficient...but need current to control all the drivers. Mine have 3 12's in each, one being passive but still to start and stop those drivers on a dime so you don't get lower bass that's rounded and sloppy, ya need some current.

You have to look at the big picture, not just a small window that audiophiles like to trounce up. Speaker design, Efficiency, current needed, volume you listen at and how big of a room your in. Everyone likes to talk watts when power is brought up, but it's a tad more complicated than simple watts.

mhardy6647

soundfreak1 wrote: »

The worst thing you can do is "underpower" speakers! Mo power mo better ( CURRENT AND WATTS) as long as its clean power.

well...kinda...maybe...

http://www.audiokarma.org/forums/showthread.php?t=549410

In case you don't know who Ken Kantor is: http://en.wikipedia.org/wiki/Kenneth_Kantor
http://www.kenkantor.com/

Pastor Bill

I'm afraid I can't answer many of the questions that mhardy raises. The spec sheet to my Model Qs is long ago gone, a Fried information site originally maintained by them is gone and I'm completely unwilling to pay $13 for a two page spec sheet as currently listed on Ebay. I "think" the Q's are fairly efficient, somewhere around 89-90 but I can't say that with authority. I've been told by those that know better than I that the Q's are not true transmission line speakers but more of a line tunnel port...aperiodic type similar to the Dynacos.

cnh

I believe 89-90 db, 8 ohms, is correct. That's not a difficult load for most of the vintage receivers I list. They'll drive those ALL DAY LONG and not ever hiccup!

I know I'll get in trouble for this. But I have found that using the "loudness" at lower volume levels really helps the Frieds' low end shine!

On another note. A friend lent me a late '80s Dolby surround AVR. Remember those?

This is a Pioneer VSX 7500S (the former 9300 but the next year Pioneer added power for the center channel so the 9300 was now the 7500 and the new model was the 9500s (125 watts x 2 in stereo). Then came the infamous D1S, even more powerful but still more of a two channel than real surround.) Well to make a long story short. I've been listening to the FM and the Frieds on this Pioneer, and I am "pleasantly" surprised that a late '80s early '90s BPC actually sounds pretty good?)

I believe that's a 9500/9700 below. But very similar, maybe two or three fewer buttons (center channel).

cnh

Pastor Bill

My past experience with other things is what motivated my question. I'm an avid motorcyclist, been riding 35 plus years. The tendency is to continually buy larger CC bikes (yes, I ride metric.) There is a vague point where the extra power, weight, etc. doesn't benefit you. For example, if most of your riding is in town and seldom exceeds 45 mph...most of your cycling needs can be handily met by 500-750 cc bikes.
Way back in the late seventies, I had a Sansui GS-7500. (I think I've got that right.) All kinds of power and bells and whistles...yet it very quickly developed a scratchy volume pot from the zero mark to about 2. Above 2, everything was clean but it was so loud at that point, I feared complaints from neighbors and hearing damage. I postulate that this happened because with all of that available...I NEVER needed to go above 2 to achieve more than adequate volume and SPLs. It was a massive brute and most of its potential was unused. Then, a channel became intermittant. I wasn't very savvy about this stuff back then...and still have a lot to learn in order to even be able to converse intelligently with most of you folk.
Call my motivation a desire for efficiency and economy.

Nightfall

cnh wrote: »

The Marantz 2215 has 15 watts x 2 @ 8 ohms continuous. Yet it weighs 24.6 lbs.

An entry level Pioneer AVR VSX 522 rated at 100 watts x 5 surround, lol! Weighs a whopping 19.8 lbs. And has a lot more in it than simple stereo processing.

Which do you think is "better built" for two channel performance? I know this is a gross comparison and weight alone is NOT the only factor. But it is ONE factor.

cnh

You also have to keep in mind that vintage receivers are made of metal and wood and the Pioneer is plastic.

cnh

Nightfall wrote: »

You also have to keep in mind that vintage receivers are made of metal and wood and the Pioneer is plastic.

Marantz weight quoted does NOT include the wood case. Just the body which is metal.

New Pioneers may or may not have a plastic front. Some have a metal face plate, and the casing is always metal. Admittedly thinner metal.

But, seriously, even with that proviso. Should a modern Pioneer AVR only weigh less than 20 lbs. And the Marantz which is rated at at almost SEVEN times less power in two channel outweigh it by 25 percent? Open the Marantz up, compare its TRANSFORMER's weight to the whimpy transformer in the Pioneer. Then look at the filter caps, etc. That's a high current design, which the Pioneer is not. At least not these lower model Pios.

cnh

Nightfall

I agree, in general weight is a factor. Just pointing out that older receivers have much heavier shells than their newer counterparts making it a little harder to go on weight alone, without taking a peek inside.

tonyb

Nightfall wrote: »

I agree, in general weight is a factor. Just pointing out that older receivers have much heavier shells than their newer counterparts making it a little harder to go on weight alone, without taking a peek inside.

True...but, weight has a lot to do with the sound too. Vibrations are better kept low with some weight to a piece. Look at tube amps, most are pretty frickin' heavy and the lust is over the iron. Also why we use spikes on speakers, to anchor that weight to something solid. So yes, a peek inside is warranted, but also weight in general can and does benefit sound....generally speaking of course.

cfrizz

pitdogg2 wrote: »

Give me sky high wattage with enough current to levitate an aircraft carrier. Even when you only listen at lower volumes I still like to be able to hear the deepest notes with authority.

Dennis Gardner wrote: »

...Personally, I prefer to have the extra headroom/power to play it louder than normal without any fear of damage to my gear.

soundfreak1 wrote: »

The worst thing you can do is "underpower" speakers! Mo power mo better ( CURRENT AND WATTS) as long as its clean power.

It is NOT just about volume as Pitdogg pointed out. And my philosophy is I would rather have it ( CURRENT AND WATTS) and not need it, rather than need it and not have it.

If you have a powerful enough amp, (I always recommend 200wpc @ 8ohms) you can use that amp with every switch to your system and speakers. The 200wpc @ 8ohms amps are usually when everyone hears a clear and distinct improvement to what they are hearing.

So my recommendation is get a receiver that has all the bells and whistles that you want it to have, and make sure it has preouts for separate amplification.

mhardy6647

I don't think anyone has mentioned that many (NOT all) modern components use switch-mode power supplies that operate at higher frequencies, requiring the use of far less massive power transformers and also less filter capacitance compared to the classic 'brute force' transformer supplies operating from 60 Hz (in the US) AC mains feeding the primary winding and variations on simple C-R-C or C-L-C filter networks.

(not to mention so-called "Class D" or "Class T" output power amplifier topologies)

I.e., weight and power - and in fact, overall quality, while we "knee-jerk" to think them correlated, absolutely don't have to be. Absolutely don't have to be.

Now, if you're talkin' about transformer-coupled single-ended vacuum tube audio output power amplifier stages -- yeah, you need lots of iron and copper to give wide bandwidth at reasonably low levels of distortion... but that's another story entirely.

Some interesting (at least partially) discourse at AK recently on (sort of) the same topic...
http://www.audiokarma.org/forums/showthread.php?t=606014

tonyb

Good point ^^^

I believe though we are talking class A or A/B amps though. Certainly other technologies don't require weight to maintain vibration control. Personally though, I've yet to hear a lightweight amp of another class compete sound wise to the more weighty tube or SS versions. Doesn't mean they can't, just that I have yet to hear one.

Dennis Gardner

I'm awaiting the "cool tube" technology that uses digital versions of the old vacuum tubes. Cool running plastic outer cases, with LEDs to mimic any amount of color cool or warm that you desire.

All the looks of vintage tubes with none of the hassles. Digital baby, that's where its at.......

soundfreak1

Not to be contrary but i've never heard any "digital" amp at any price to compare with SS or tube equip.

cnh

Dennis Gardner wrote: »

I'm awaiting the "cool tube" technology that uses digital versions of the old vacuum tubes. Cool running plastic outer cases, with LEDs to mimic any amount of color cool or warm that you desire.

All the looks of vintage tubes with none of the hassles. Digital baby, that's where its at.......

I don't know if that is even possible, but it would be COOL (in all its meanings!).

cnh

cnh

mhardy6647 wrote: »

I don't think anyone has mentioned that many (NOT all) modern components use switch-mode power supplies that operate at higher frequencies, requiring the use of far less massive power transformers and also less filter capacitance compared to the classic 'brute force' transformer supplies operating from 60 Hz (in the US) AC mains feeding the primary winding and variations on simple C-R-C or C-L-C filter networks.

(not to mention so-called "Class D" or "Class T" output power amplifier topologies)

I.e., weight and power - and in fact, overall quality, while we "knee-jerk" to think them correlated, absolutely don't have to be. Absolutely don't have to be.

Now, if you're talkin' about transformer-coupled single-ended vacuum tube audio output power amplifier stages -- yeah, you need lots of iron and copper to give wide bandwidth at reasonably low levels of distortion... but that's another story entirely.

Some interesting (at least partially) discourse at AK recently on (sort of) the same topic...
http://www.audiokarma.org/forums/showthread.php?t=606014

Lost your calling as an attorney, perhaps? lol

Just pulling your leg, a little.

cnh

Pastor Bill

Forgive my ignorance...I really want to learn. Question: is it possible to attach another amplifier to the NAD 7140? In between the pre-amp out and the amp in? (I'm assuming this) Or is this just to allow a signal processor such as an equalizer? On the back of the receiver, these two are bridged together with U shaped bridges. The instructions aren't that clear to me.