Yes, a watt is a watt, but, the way most tube manufacturers measure their gear, a tube watt is, arguably, LESS than a solid state watt because tube manufacturers typically spec the output at a much higher allowed distortion level.
BUT, measurements notwithstanding, I actually have heard many demonstrations where a low-powered tube amp is perceived to sound louder than a much higher powered solid state amp. In such demonstrations, neither amp was pushed to obvious clipping. At modest or low sound levels, I think that many solid state amps sound dead and lifeless. To get them to sound livelier, one tends to push the volume. When heard side by side at the same volume, one is often struck by how much better a well designed tube amp sounds compared to a comparable solid state amp, and because so many audiophiles conflate sound characteristics down to some simple measurement, like power and distortion, they concluded that the better sounding amp is more powerful. |
well some of them isn't most of them. it's nature of tubes and output transformers. they're weak when impedance of speaker goes down on low frequencies. |
I will let the more technically astute than I debate the technical side of this
issue, but experiences with both tube and ss amps have shown me that
there is much more going on than "a watt is a watt", or wether
the amp in question is driven into clipping and how it reacts to being driven
into clipping. One experience in particular proved this to my ears:
I bought my first pair of Stax F-81 electrostats back in early '90's when my
system included a NYAL Moscode 600. The Stax are known for being a
brutal load for most amps and very inefficient. The Moscode is a well
regarded hybrid amplifier which delivers 300 ss watts per side and which
had, up until then, done a good job of driving a variety of speakers
including Thiels, Magnepans, and others; and sounded good doing so.
After looking for the Stax (which I considered, and still do, to have the best
midrange I have ever heard) for quite some time I finally found a pair. I still
remember well the disappointment I felt when I set up the Stax and heard
how poor the sound was. There was plenty of volume (as much as the
Stax can provide) without any obvious distortion, but the sound was thin,
lifeless and grainy. This led to trying several different speaker cables and a
couple of different preamps (?). No significant improvement; bad sound.
I was ready to sell the Stax when, coincidentally, I visited my local
appliance repair shop to buy some vacuum cleaner bags and I noticed on a
back shelf a repaired Dynaco ST-70 which had not been picked up for
months. The shop sold it to me for the cost of the repair ($85). I brought it
home and, just for the hell of it, replaced the Moscode with it; thinking, no
way! To say that I was amazed at the result would be a huge
understatement. The Dynaco's 35 tube watts did not play as loud as the
Moscode's 300 ss watts (duh), but it sounded beautiful (by comparison),
fairly refined, dimensional, and within a more narrow dynamic range it let
the music flow and move as it should; the music finally sounded alive. I
bought another pair of the Stax more recently and drive them to great effect
with Manley 200 tube monos. Ever since that first Stax/Dynaco experience
I have owned only two ss amps (BEL and Levinson) and compared to the
Manley 200 mono's which I currently use the differences between the ss vs
the tube amps are very similar to the differences between the Moscode and
the Dynaco; although at a much higher level of overall fidelity. |
Tube amps using ultra-linear mode of operation use a lot of global negative feedback to generate a higher wattage. Bombaywalla, taken either in or out of context its hard to take this comment seriously. I've modified many Dyna ST-70s where the only feedback was the ultralinear operation itself and the amps worked fine. But the real problem with this statement is you can't apply feedback to get greater power. If the amp is capable of greater power is something entirely independent of feedback.
"Output stage coupling is a combination of “ultralinear” and Audio Research’s patented “partially cathode-coupled” topology, which is superior to conventional pentode or triode operation."
Its funny to me that they got a patent on that since Leslie amplifiers (of Hammond organ fame) had used the same technique in the 1950s.
I'm not even treading into the realm of "is 14dB too much global negative feedback?"!! ;-)
14 db is an 'inbetween' figure which normally leads to *increased* distortions of some harmonics, but as others have said the ARCs use other forms of feedback as well- ultralinear being one, and the cathode cross-coupling being another. If neither technique were used 14 db would very likely be problematic.
tube amps have no bass hence it's power mostly applied towards mids and highs while the solid state amps go full range.
As prediceted, I take umbridge with this remark as it really is simply false. Our amps make full power to 1 or 2Hz depending on the model. But what is really going on here is that most box speakers don't have decreasing impedance as frequency goes down; while many have dual woofers arrays, they will also have an impedance peak that is part of the resonance of the drivers in the box. So if you have a 4 ohm tap you can likely make that work on a tube amp. More importantly is the question of whether that's even a good idea, as every amplifier technology known has audibly higher distortion when driving lower impedances. I've yet to encounter a good reason for increasing amplifier distortion if sound quality is the goal!!
well some of them isn't most of them. it's nature of tubes and output transformers. they're weak when impedance of speaker goes down on low frequencies.
This statement is false. First- tubes are not frequency-dependent devices and often have bandwidth far in excess of most semiconductors. The design of the output transformer is the real variable- its no problem designing one that will do quite well in the bass. The trick is doing that and getting the highs right at the same time.
Yes, a watt is a watt, but, the way most tube manufacturers measure their gear, a tube watt is, arguably, LESS than a solid state watt because tube manufacturers typically spec the output at a much higher allowed distortion level.
This statement is misleading. The way both solid state and tube amplifier manufacturers do it is with **the onset of clipping**. Many tube amplifiers will have higher THD at the onset of clipping than solid state amps might. FWIW that THD is usually of lower-ordered harmonics that the ear finds to be musical, whereas solid state amps are far more likely to have much higher levels of the 7th harmonic, which the ear finds to be really objectionable. Hence the tube/transistor debate over half a century after tubes were declared 'obsolete' and yet the tubes are still here. And if you are thinking 'well all we have to do is build a solid state amp that doesn't make any 7th and it will sound as smooth as tubes' you would be nearly correct, so have at it!! The best designers out there (Nelson Pass, John Curl, Charlie Hanson) are all aware of this fact and have been for a long time. Its no coincidence that they have designed some of the best sounding transistor amps made. |
Ralph,
thanks for pointing this out - you're right feedback & output power are not related. I should have written that sentence differently pointing out that output power depends on the topology of the tube - triode vs. ultra-linear vs. pentode with the output power going progressively higher as one moves from triode to pentode. |
10-11-15: Bifwynne
Thanks Bombaywalla. I really enjoyed reading the 1983 Atkinson and Messenger ...... welcome Bifwynne. yeah, I figured it might be difficult to understand what was written in that patent application not only because of the material of the subject but also due to the fact that it was written in technical legal-ese that patent attorneys love! I believe that the basic premise of the partial cathode-coupling in the ARC output stage is to reduce output distortion while reducing impedance in the output stage circuit at the same time. This technique also allowed the ARC amps to have a "complex load driving ability" (written in his patent application) which in plain English means that they could drive tough speaker loads (the types that exhibit crazy phase angles that flip between capacitive & inductive over the audio spectrum). |
10-12-15: Frogman
I will let the more technically astute than I debate the technical side of this
issue, but experiences with both tube and ss amps have shown me that
there is much more going on than "a watt is a watt", or wether
the amp in question is driven into clipping and how it reacts to being driven
into clipping. I'm afraid that a watt is a watt & it is the distortion characteristic of a tube amp vs. that of a s.s. amp that appears to give the listener the impression that a tube watt is more powerful than a s.s. watt. It is not. I bought my first pair of Stax F-81 electrostats back in early '90's when my
system included a NYAL Moscode 600. this makes sense - an amp that is good for driving dynamic cone type loudspeakers (Thiel) & magnetic planners (Magnepan) cannot be assumed to be good enough to drive an electrostatic speaker. Electrostatic speakers are effectively a large capacitor to the power amp. This model of a capacitor for an electrostatic speaker comes from the fact that you have a stator on either side of the rotor/energized thin film that effectively creates 2 parallel plates of a capacitor where one is the top-plate & the other the bottom plate. Both stators create either the top-plate or the bottom plate. If the electrostatic loudspeaker looks like a large capacitor to the power amp, it also means that the impedance of such a speaker follows a 1/f profile i.e. speaker impedance is very high at low freq & very low at high freq. Just the opposite of a cone type speaker or even a magnetic planar. Since the electrostatic speaker's impedance is very high in the bass region, guess what?, the power amp has to pump current into a high impedance at the bass freq. Any s.s. or hybrid amp (which acts like a constant voltage source) will reduce its output with increasing speaker impedance. No wonder your NYAL Moscode 600 sounded horrible with an electrostatic & it was totally expected. A tube did much better because most tube amps act like constant power sources constantly adjusting their output current & output voltage to keep output power constant as the speaker impedance changes. This also means that a tube amp can give you relatively constant power (20% variation can be expected) over the 20Hz-20KHz range while a s.s. & hybrid amp will decrease its power into a higher impedance speaker load. it is no wonder that the Dynaco outdid your NYAL hybrid amp. Totally expected. You have to be very careful which amp you connect to an electrostatic speaker due to the speaker looking like a capacitor to the power amp. Most power amps oscillate & self-destruct when they have to drive large capacitive loads. It is no coincidence that SoundLab customers use tube amps almost exclusively (I think a lot of them use Atma-sphere amps) & that Sander Sound Labs makes a special s.s. amp for electrostatic speakers. |
Are you trying to tell tube/solid state amps measure RMS differently? |
A watt is a unit of quantity and all are the same, but each case is different regarding the characteristics of each watt produced and how it sounds. Same amp can perform radically different with different speakers.
So saying a watt is a watt is true in theory in terms of how much power is generated, but in practice, all watts will be different sounding case by case. So there is certainly credence in saying that and value in knowing it, but alone it still determines only one piece of the puzzle in practice. |
Compare Alan Watts to Reggie Watts, and you will find that one continues to produce sound and the other does not. |
Another thank you, Bombaywalla!
For the most part, I've never much cottoned to ARC (or, CJ) products. As time moves forward, I tend to like the newer ARC products even less. Still, outside of the commentary OTL and a certain slant on the power supply, I came away more than impressed with how Mr. Johnson thinks and feels. Call it new found found respect.
Anyway, the contrarian part of my post is that a watt is NOT just a watt. We measure power under steady state conditions, using a resistive load. Music is anything but steady state, and despite Bud Fried's raison d'etre, loudspeakers are not at all resistive loads. Not to complicate matters too much, but loudpeaker (bass alignment AND crossover design) topology will greatly impact how much power an amplifier can put into it.
That said, all things equal, I've seen so many less powerful amplifiers put out more seat of the pants power than higher power amplifiers, and have come to the conclusion that the audio industry has not properly discovered how to measure actual / real-world / musical power. The most obvious example I can list is an 11 wpc push-pull 2A3 tube amplifier that thoroughly out-muscled the same manufacturer's 120 wpc hybrid tube / solid state product. |
10-12-15: Trelja
Another thank you, Bombaywalla! welcome Trelja. |
10-12-15: Beavis
Are you trying to tell tube/solid state amps measure RMS differently? Since Mapman has not answered till now & if I may be permitted to reply in his stead understanding what he is trying to say then......... no, he's not saying that s.s. & tube amps measure RMS differently. That simply cannot happen - RMS is RMS no matter which amp. i think he's saying the same thing Atma-sphere & I & others have already written which is: a watt is a watt but each amp reacts differently with each speaker. And, it is this interaction between amp-speaker that determines when & how much an amp will distort. This, in turn, will give the illusion in some cases that tube watts are more powerful than s.s. watts (they really are not). |
Watts are not Watts. The reason tube amps have better Watts than solid state amps is pretty simple. It's because they generally have more dynamic headroom than solid state amps. Thus all things being equal tube amps won't clip as soon as solid state amps. Case solved. |
I should have written that sentence differently pointing out that output power depends on the topology of the tube - triode vs. ultra-linear vs. pentode with the output power going progressively higher as one moves from triode to pentode. Really it depends on how many tubes are used. Our MA-3 makes over 500 watts and its entirely triode, yet the H/K Citation 2 is pentode and only makes 60 watts. I think what you were trying to say in this passage is that pentodes **usually** pack a lot more power per tube than triodes usually do (there are triodes out there that make a lot of power; more than most pentodes). Ultra-linear is a means of approaching triode linearity while retaining the power output of a tetrode or pentode (either can be used in ultralinear). The use of tetrodes, pentodes, triodes and ultralinear operation otherwise has nothing to do with power at all. i think he's saying the same thing Atma-sphere & I & others have already written which is: a watt is a watt but each amp reacts differently with each speaker. Actually I was more commenting on strictly how the amps distort- tubes interact favorably with human physiology while generally transistors do not (lower ordered harmonics as opposed to the dreaded 7th harmonic). This interaction can be quite profound and hard to turn down when you hear it! A few years ago my band was at a show in Chicago. There were a lot of bands on the bill and to save time with each one shifting gear on stage, we offered to 'backline' our bass amplifier- a 400-watt Peavey ('backlining' is the process of having some equipment left on stage that all the bands would use during the show). One of the bands had a 500-watt Orange bass amplifier, which is class D. He wanted the extra power. He was quite blown away when I pointed out that a class D 500 watt amplifier would in no way keep up with a 400 watt tube amp on stage. He tried it and agreed- but had to go back to the class D amp as the Peavey made far more bass energy than he was used to- he was used to the thinner sound of the class D amp and was a little panicked that he would not be able to get the right sound (they were going on first). |
Geoffkait,
How about Amperes, Volts and Ohms are they also better?
Ampere, Volt, Ohm and Watt were dudes that named these units of measure. I would suggest you to provide quantitative answer to your hypothesis by deriving your own unit of measure by how much of your units TubeWatts are better than SSWatts. |
|
Czarivey, good question. Yes, they're better, too. |
...but can you give algebraic or geometrical representation so everyone can understand? |
Geof will then rewrite all the textbooks on the subject as well I'm sure. :^} |
Bottom line is watts matter be you tube or SS but you gotta take all power specifications with a grain of salt because no specification completely and accurately tells you whats happening in regards to distortion, which all amps produce to some extent and in different ways, some less offensively than others. Neither SS or tubes own the game in this regard. |
Geoffkait's dynamic headroom theory falls apart when faced with a class A amplifier, which can be either tube or solid state.
The Dynamic headroom of an amplifier is measured in decibels, and has to do with the class of operation and the amount of energy storage in the power supply. The spec is rarely used today. The more dynamic headroom, the poorer the amp in general; the idea being that if class AB and without much power supply, for a brief instant the amp will be able to make more undistorted power than its constant power spec.
A Class A amplifier will have 0 db of dynamic headroom. A really bad amp will have 3 db of dynamic headroom. The spec was created in the 1970s to make cheap amplifiers look good on paper. |
A worse amplifier has higher dynamic range? Worse how? Because it clips easier? And therefore has more gross distortion at volume? Because it has less dynamic range? Worse it has an order of magnitude higher THD than the "better" amp? I see where this is going. :-) |
You educated guys now totally confused the hell out of me.
So what should I want? Class A 500 wt/ch tube amp? |
Large headroom doesn't mean poor performance. It means that amp has ability to output higher momentary peaks. Otherwise it is power limited by power supply and/or heatsinks. That's what music is - peaks, gaps and very low average power (few percent of the peak). Power test is done with continuous sinewaves. |
I think there have been some designs over the years that advertised large headroom out of a more compact box in particular that were not very good sounding overall on teh grand scale of things. I had a Hitachi Class G receiver for many years that fit this mold.
But I would agree with Kijanki's depiction of headroom.
Soft clipping amps, tube or otherwise are another way to get around the challenge I suppose. Those cannot be accused of having large headroom at higher volumes. They are designed explicitly to LIMIT the headroom in a manner that is not overtly offensive to the listener. |
Large amounts of dynamic headroom can be viewed two ways: The amp can put out a considerably greater amount of power for relatively brief periods of time than it is rated to deliver continuously, or the amp can **not** sustain power outputs that are close to its maximum instantaneous capability for longer than relatively brief periods of time.
I agree with Ralph/Atmasphere that in general it would be wise to consider a particularly "good" dynamic headroom spec to be a caution flag.
It's also worth noting that relatively low powered SET amplifiers are often considered to be especially good when it comes to reproducing musical dynamics (due particularly to how their distortion characteristics vary as a function of signal level, as Ralph has explained in the past), yet as class A amps they have zero dynamic headroom.
Best regards,
-- Al
|
One strike against Class A tube amps in particular is their very high cost, has anyone actually checked out what a good 100 Watt Class A tube amp goes for? Hel-loo! One assumes you're NOT referring to milli watt SET headphone amps, not that there's anything wrong with them as all. |
"The amp can put out a considerably greater amount of power for relatively brief periods of time than it is rated to deliver continuously, or the amp can **not** sustain power outputs that are close to its maximum instantaneous capability for longer than relatively brief periods of time."
Al, what's the difference other than worded?
Is there an amp not capable of putting out more power cleanly for a shorter period of time? Soft clipping amps which tend to lessen the need considerably and enable fewer watts to "go further" perhaps?
In any case, one wants to avoid the extra distortion that most amps will produce when pushed hard by not having to run them too hard. I think that's a good rule to follow in all cases. |
Mapman, my point is that without further information one doesn't know whether to view a "good" dynamic headroom spec as the glass being half full or being half empty, so to speak. And my perception over the years and decades is that a "good" dynamic headroom spec often (although not always) correlates with lesser quality (and less expensive) designs. Is there an amp not capable of putting out more power cleanly for a shorter period of time? Most well designed class A amps would be good examples, as Ralph indicated. In fact with a class A amp, as I understand it, the more power is continuously delivered to the load, the less power the amp will dissipate internally, and therefore the cooler it will run internally. Which suggests the possibility that in some cases a class A amp might even be able to deliver slightly more power continuously than briefly. Re your last paragraph, I would certainly concur. Best regards, -- Al |
"Class A 500 wt/ch tube amp?"
That should do nicely if you can afford the power bills. Doesn't Ralph have one of those? |
I have a 500 w/ch Class D amp. Class D is a different beast. It is designed to deliver the power only as needed as I understand it. That's what enables it to be small powerful and energy efficient. It never breaks a sweat or sounds strained at ANY volume, is as musical as anything I hear. It also soft clips to boot I believe. I've never heard anything less than lovely come out of these.
I'd compare that to my old Hitachi SR804 Class G 50 w/ch amp that advertised 100 w/ch headroom as I recall. This was quite midfi at best in comparison but a very nice looking unit with a very good tuner. My conclusion is that switching technologies that enable such things have come a long way and are now capable of doing things as well as most anyone might expect or need.
I also have a 60 w/ch Class D integrated with next generation Class D technology in it. htis does not go as loud but does exceptionally well, the best 60 watts out of an integrated amp I have ever heard by far. |
Tell us, once more, about Ohm speakers mapman
It's been at least 2 days
Yawn......................... |
Al and Ralph ... help me with the terminology. When I think of headroom, I think of an amp's ability to handle short term dynamic transients, which is part of real music ... especially classical music.
To be more specific, my tube amp has a 1040 joule power supply. In my "un-technical" way, I interpret that as "head room" because my amp presumably can handle short term power demands that exceed its rated power output of 150 wpc, subject to FR, speaker impedance and tap output impedance. Am I mixing and matching terms and concepts here?? |
ss watts can be misunderstood as well. "Qaulity" watts matter more than quantity. The more important consideration if the amp's ability to drive a low impedance load and remain dynamically stable. Thus the power supplies are critically important. You want a large, highly efficient multi-regulated power supply with a high current and a good damping factor. For example, my Vitus SIA-025 has 'only' 25 watts kl.A power & 100 watts kl.A/B (switchable), but has a very efficient 1.4kVa UI-core transformer which is capable of controlling low impedance loads running in kl.A mode. Big transformers also tend to be heavy, and the SIA-025 weighs 42kg. Compare that to the Accuphase E-600 which weighs 24.7kg. I can't think of any other class A ss which integrated amp which can do that. Similarly tube amps can have some pretty hefty transformers. I know the Absolare 845 mono blocks were driving the S5's comfortably at CES last year. |
Bruce (Bifwynne), from John Atkinson's measurements of your ARC Ref-150: All taps behaved similarly when it came to the maximum output power. Into a load twice the nominal tap value, the Ref150 clipped (defined as 1% THD) at 90W (19.6dBW, fig.4). Into the nominal tap value, it clipped at the specified 150W (21.75dBW, fig.5), but with a higher level of distortion. Into half the tap value, the amplifier clipped at 80W (13dBW, fig.6), but with even higher distortion at lower powers. It is important, therefore, to use the transformer tap that best matches your preferred loudspeaker. And from ARC's specs for the amplifier: 150 watts per channel continuous from 20Hz to 20kHz. 1kHz total harmonic distortion typically 0.6% at 150 watts, below 0.03% at 1 watt. Approximate actual power available at ‘clipping’ 160 watts (1kHz). (Note that actual power output is dependent upon both line voltage and ‘condition’ i. e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not very critical.) So since the spec for the clipping point (presumably corresponding to the amp's maximum instantaneous power capability, for some reasonable amount of distortion) is negligibly higher than its maximum continuous power capability, the amp's dynamic headroom is close to zero. The way to look at it is that the very high energy storage capability of its power supply helps the amp to achieve a continuous power rating that is close to its clipping point, rather than being significantly less than its clipping point (as it would tend to be in the case of an amp having a significantly less robust power supply). As well as perhaps providing other benefits, such as minimizing the extent to which the perceived dynamics of the amp might be compromised by sluggish responsiveness of the AC supply to abrupt increases in demands for current. Note Ralph's earlier statement that "if class AB and without much power supply, for a brief instant the amp will be able to make more undistorted power than its constant power spec." Or putting it the other way around, if class AB and without much power supply, the constant power spec will be much less than what the amp can supply for a brief instant. Best regards, -- Al |
Thanks Al ... the problem is my misuse of terminology.
Perhaps a better way for me to think about my amp's performance window is that it does not appear to choke when asked to deliver power. Perhaps that is because I am not really tasking the amp all that much during "normal" operations.
In my layman's way of thinking, what I think of as "headroom" is my perception that if the amp is making say 25 to 50 watts of power during "normal" operations, a transient peak that pushes the amp out to 100+ watts is well within its rated power capability. Not headroom in the technical sense, but headroom insofar as the amp can produce a lot of power at reasonably low distortion numbers and remain stable.
Another fine point from the Atkinson report is that my amp will produce rated power in those cases where the load impedance matches the nominal tap value, i.e., an 8 ohm load plugged into the 8 ohm tap; or a 4 ohm load plugged into the 4 ohm tap. However, the amp will not produce rated power where there is an impedance mismatch between load and nominal tap value.
That said, in my case, my speakers have a 4 to 6 ohm saddle in a good part of the low frequency range, say 70 to 500 Hz. Impedance goes vertical past 700 Hz.
I surmise that most of the power demands placed on my amp fall within those goal posts. Given the foregoing, the 4 ohm taps make the most sense from a impedance and power matching perspective. And as an aside ... my rig sounds the best to my ears off the 4 ohm taps too. |
Yes, that all sounds right to me, Bruce. It's a very powerful, robust, and undoubtedly dynamic sounding amp. Despite, and in a sense because of, the fact that it has essentially no dynamic headroom in the technical sense.
Best regards,
-- Al
|
Makes sense. I hadn't really given the term dynamic headroom much thought of late with the realization that underbuilt amps that claim to be able to do great things for brief periods of time historically tend to not pan out that well.
But Al, how to reconcile Class D amps? I've seen headroom mentioned with them but not really a focus there either given the radically different way Class D operates. Its almost exclusively about delivering a large amount of power and current only at the times the music requires it as I understand the technology. |
Gee, in all this time on this thread no one has bothered to mention the most distinguishing feature of tube amps vs solid state amps. That is the lack of the irritating harmonics present in solid state amps. Not to mention the more natural and realistic presentation. So, in that sense tube Watts are actually even better than solid state Watts than if we only consider dynamic headroom. |
Hi Mapman,
In your last sentence you probably meant to say "drawing" rather than "delivering," the former (referring to AC **input** power) being consistent with class D's very high efficiency. While dynamic headroom, of course, has to do with the difference between short-term and long-term **output** power capability.
I don't have a great deal of familiarity with class D designs, so I'm hesitant to comment. But I seem to recall reading that some class D modules have limitations (measured in minutes) with respect to how long they can sustain their rated maximum output power. And also that amplifiers from different manufacturers using the same class D module will often have considerably different max power specs. So it seems to be a different ballgame when it comes to class D, that may be hard to pin down with respect to dynamic headroom. Not surprisingly, given the radically different technology.
Best regards,
-- Al
|
Geofkait,
You are either autistic(which happens to many Americans for known reason) or didn't grow up yet. |
To be more specific, my tube amp has a 1040 joule power supply. In my "un-technical" way, I interpret that as "head room" because my amp presumably can handle short term power demands that exceed its rated power output of 150 wpc, subject to FR, speaker impedance and tap output impedance. Am I mixing and matching terms and concepts here?? Yes. Its important to understand that the concept of 'dynamic headroom' and the resulting spec was entirely 100% marketing on the part of the manufacturers of inexpensive amps and recievers during the 1970s. A worse amplifier has higher dynamic range? Worse how? I did explain that in my prior post, here it is again: the amp has a small power supply that will not allow it to operate at full power continuously. On top of that, it would probably overheat if it did due to poor heatsinks. Further, it is biased class AB and likely exiting the A region with less than 1/2 watt output. These properties will allow the amp to put out brief spikes of power that otherwise its design does not allow in a steady state condition. The higher the headroom number (in db) the cheaper the amp. Class D FWIW is not an exception to this rule of thumb- the best class D amps will make about the same power whether continuously or not. |
"And also that amplifiers from different manufacturers using the same class D module will often have considerably different max power specs. "
I know that often different manufacturers interested in optimizing performance use customized power supply circuits to that end. Bel Canto with their M series amps is an example. Accountings I have read support the notion that the power supply used makes a big difference in class D amp performance as well, but given the nature of Class D switching technology, these can be much smaller and lighter than what is required to power comparable Class A or A/B.
I have also read of some high end Class D amp vendors using more traditional larger and heavier power supplies with their Class D amps to help assure the nth degree of performance I would assume. |
|
Czarivey, yeah, I guess you're right. it's really the Americans who have been brainwashed. ;-) |
Well, I learned something new about dynamic headroom and why it often is not a good thing when advertised even though it sounds like it is. These guys are trickier than big tobacco even!!! |
Gee, in all this time on this thread no one has bothered to mention the most distinguishing feature of tube amps vs solid state amps. That is the lack of the irritating harmonics present in solid state amps. Actually I did allude to that earlier... |
"That is the lack of the irritating harmonics present in solid state amps."
Present in many perhaps but not all. |
Mapman, really? Which ones? I'm dying to know. |
