Tube Watts vs. Solid State Watts - Any credence?

For what it's worth, IMHO, and I am certainly no 'techie' in this hobby, but what is 'better': tube vs. ss, 70 watts (tube OR ss) vs. 140 watts, monos vs. stereo amps, EL 34s vs. KT 88's, push pull vs. SET, U.S. made vs. European vs. Asian produced, class D vs. class A or A/B is so incredibly subjective as to render all discussions little more than entertaining exercises making comparisons and demonstrating experience, knowledge and preferences. Recently I bought my first set of class D monos (Bel Canto M1000) because I wanted more power than what my class A 80 monos produce. 500 watts vs. 80 at 8 ohms. Also in the mix is my 250 watt ss Halo A21. Class A vs. A A/B vs. high powered class D. I've owned SET's, EL-34 based, KT-88 based, high powered, low powered tube amps, you name it. Do the 500 watt class D amps play louder? Maybe. If so, not by much because once all 3 are stretched out to about as loud as I can stand it, I quit turning the volume knob up on the pre-amp. To me the lesson is this: buy what sounds good to you, and buy ample power so that your amps don't clip at max volume because that is what fries tweeters, not an overabundance of power, but a dearth of power. In my case I really like the sound of all 3 amps, so which to keep? All 3 play plenty loud, so which are more practical, look the best, demand less energy, appeal to me subjectively? That's the fun part of the hobby. My 2 cents. Good luck!

Djfst,

You can easily divide your 'tube watts' by 2 in most of cases driving Sonus Faber speakers...
So your tube watts are actually halved making you believe that they're loud.

They simply don't see anything below 60Hz due to the struggle with tough load. Most of the power of solid state "watts" are thrown to reproduce bass frequencies below 60Hz.

If you REALLY want to benefit from your tube watz u need to purchase amplified sub-woofer.

No rocket science at all.

Geez, guess I'll have to send both of my 62lb output transformers back, then...

The large magnetic field produced by large transformers cannot be good for any frequency, high, low, what have you.

How does a large power transformer affect high frequencies?

Output transformer, maybe...

^sensitivity 91 dB, 4 Ohm nominal.

And without knowing the, uh, drum roll please, efficiency of the speakers.

Djfst, I do believe your original question has been answered.
Without knowing the minimum impedance and phase angle of your speakers, as well as the dimensions, etc. of your listening room and volume levels you hope to achieve, it's problematic to provide quality technical assistance.
With what you have provided, IMHO a conservative recommendation to start with(?), might be to use a ss amp rated at 100 Watts that can double down, or a tube amp that's rated at 200 Watts.

85W vs 70W 5.7% loudness increase
45W vs 40W 3.4% loudness increase

The EL34 has a very good reputation in the sound department. A lot depends on how well the ultra-linear taps on the transformer are executed; if done correctly the linearity is just about the same as triode so my vote is for the EL34 in ultralinear mode, assuming the transformer is designed correctly.

Djfst, the differences in power which you cited all amount to less than 1 db, in most cases much less than 1 db, which is negligible. Even a doubling of power would amount to only 3 db, which while easily perceptible is not a huge increase.

In addition to researching which of those tubes others have reported to be preferable in the particular amp from a sonic standpoint, preferably with SF speakers, you might try asking Kevin Deal at Upscale Audio for his recommendation. In addition to being a very knowledgeable seller of tubes, he is the USA importer/distributor for PrimaLuna.

Regards,
-- Al

Sorry I know nothing about what tubes will work best there. Others probably will. Cheers and good luck!

Some 100 posts in and no one has really answered most of my questions, at least practically speaking for decision making. So I will ask again…

A practical question out of all of this is power tube choice in the same amp. Currently am running eight EL34's tubes in a primaluna HP integrated amp to Sonus Faber Olympica III speakers. The Sonus Fabers are 91db, 4 ohms, and recommended amplification of 50-300 watts.

Tube choices in the amp are as follows:

ULTRALINEAR MODE:
85 watts x 2 (KT120)
73 watts x 2 (KT88)
70 watts x 2 (EL34)

TRIODE MODE:
45 watts (KT120)
42 watts (KT88)
40 watts (EL34)

I know tubes have there own characteristics, but besides that, from a power standpoint, would it be better to go to KT120s to get more power to my speakers? Would the difference in wattage moving from EL34s to KT120s (15 watts increase in ultra linear, 5 watt increase in triode), be beneficial or even perceptible to my ears? Would this be better for the performance of the speaker, or at least the health of the speaker?

"If you really want an amplifier that is as smooth as a tube amp you are going to have to get a tube amp (its the lack of the 7th harmonic that makes them smooth)."

I suppose so. But having heard many amps of all kinds, including both tube and SS amps in what most would regard as "reference systems" I have found a tube amp is NOT what I want and I am happy with what I have. It provides hours on end of musical enjoyment. Irritation has been a problem in the past with some amps but is not an issue with the amps I use now, which are both Class D amps by Bel Canto. The TAD Hibachis were a hit for me as well.

There are many things that go into good sound. It either works or not. If i find it works well, i am not going to worry about individual theories about what's really going wrong. When it sounds wrong or irritating, I will do something about it, but it does not.

That's just my experience. FWIW. Not that I do not like the sound of a good tube amp, but having dabbled with tubes again in recent years, its all the rest that goes along with it that I still do not want.

I might feel differently if not for having found Class D to be a better option for me.

"A solid state amp that sounded identical to a tube amp? That's gold, Mapman, gold! Humor is the best medicine. ;-)"

Not to spoil your little chuckle, but that was Bob Carver who made the claim, not me. He's done a few things designing gear over the years but take it for what its worth.

I can only vouch for the fact that the amp was not irritating. Like most good quality amps, including tube amps, it sounded very good with the right speaker match. Harmonics did nt seem to be an issue.

Mapman, while there are some solid state amps that have less of the 7th harmonic that has become the hallmark of transistor amplification, there are none that are at the low level that tube amps often demonstrate, although I think there are a few that come close.

Class D is no exception, at least not with any of the amps I have heard and own. Their artifact does seem different than the traditional transistor type; so far it seems that no-one can make an amplifier that is truly neutral.

If you really want an amplifier that is as smooth as a tube amp you are going to have to get a tube amp (its the lack of the 7th harmonic that makes them smooth). If you want to avoid that 2nd harmonic that makes tubes so lush you have to avoid amplifiers that employ single-ended circuits.

A solid state amp that sounded identical to a tube amp? That's gold, Mapman, gold! Humor is the best medicine. ;-)

All Class D amps I have heard are the opposite of irritating. Go listen and see which ones you find irritating or not. I've heard Bel Canto and Rowland mostly.

Atmasphere has cited certain Pass amps and others I recall that are not prone to irritating harmonics as well. He would know best probably.

I also recently owned a pair of SS Tube Audio Design Hibachi amps that advertised little or no negative feedback and would also fit the bill I would say.

I owned a pair of Carver SS m4.0t amps for many years that performed much like a tube amp. Those were designed to demonstrate a SS amp that sounded identical to a specific tube amp.

I've heard many other musical not irritating SS amps as well. If bad harmonics = irritating then these did not have that affliction either, FWIW.

All Class D amps I have heard are the opposite of irritating. Go listen and see which ones you find irritating or not. I've heard Bel Canto and Rowland mostly.

Atmasphere has cited certain Pass amps and others I recall that are not prone to irritating harmonics as well. He would know best probably.

Czarivey, your insensitivity is only exceeded by your ignorance.

Mapman, really? Which ones? I'm dying to know.

"That is the lack of the irritating harmonics present in solid state amps."

Present in many perhaps but not all.

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...

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!!!

Czarivey, yeah, I guess you're right. it's really the Americans who have been brainwashed. ;-)

Have a nice Day, Andrew.

"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.

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.

Geofkait,
You are either autistic(which happens to many Americans for known reason) or didn't grow up yet.

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

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.

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.

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

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.

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

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.

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??

Tell us, once more, about Ohm speakers mapman
It's been at least 2 days
Yawn.........................

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.

"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?

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

"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.

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.

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

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 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.

You educated guys now totally confused the hell out of me.
So what should I want? Class A 500 wt/ch tube amp?

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. :-)

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.

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.