Class A power amps and electricity crisis..

[the sound of Tao]

If you wanted to, yes, but I can't think of a reason to do that.

You have to consider that we've been making class A triode zero feedback OTLs for nearly 50 years. We've had lots of opportunity to compare them to other tube amps- PP KT88, SET, PP triode, you name it. I own a variety of amplifiers as you might expect. As long as our OTLs and the other amp in the comparison are happy with the speaker load (and this is usually to accommodate the OTLs, which don't like low impedances unless very large), I've yet to hear another amp that actually sounded better. Not saying our amps are the best, clearly I've not heard everything on the planet!! But if we can hear a solid state amp that sounds better in nearly every way (depth, width, detail, lacking brightness, similar smooth midrange, good bass extension and impact) then that suggests to me that tubes insofar as hifi tube power amps are concerned are indeed on borrowed time. The only downside we've heard is that the class D overloads like a conventional solid state amp while the tubes are very graceful about it. So as long as you don't overdrive the class D it seems to be no worries.

So that's the sonic upside. Add to that no degradation over time as tubes age, hardly any heat, instant warmup to sound right, maybe about 5 Watts at idle and seriously, why would you bother with tubes unless you simply are going for the visual aspect? I get that part, but when you know that you can do better when its actually running? The bottom line still has to be the sound, doesn't it?

If they measure and sound right then we will.


That will depend on the amp. Self-oscillating amps will be more immune (due to increased noise rejection properties) to the power line vagarities; zero feedback class D amps will benefit more. The PS Audio power re-generators can regulate line voltage and that's good if you have issues with power line voltage.

Nothing to be sad about! Apparently a lot of people are surprised by my attitude in this regard- and quite a few also that that we even had a class D project. Apparently there is this story out there that if you make tube amps you're somehow inherently unable to do design work or something, and maybe even have a bias. From a personal perspective, I find that being pragmatic has helped me more than hindering me in my own personal quests.

I used to think that too- I call it 'emotional involvement'. When the music is processed in the limbic centers of the brain rather than the cerebral cortex (the latter which happens when things don't sound right to the unconscious mind) then you get increased emotional awareness in the music- toe tapping, tears, that sort of thing.

The truth of the matter is when the music is right, not due to a particular form of amplification!



The thing to understand here is that class D amps vary in sound more widely than any other amplifier class. From the worst cheapest tube amp to the best you can think of, that variation is not as wide as class D! So a blanket statement about the technology's 'sound' is going to be inherently false (other than this one ).


If we are being honest about keeping a 1940s amp in service, the 'minor' repairs are not that minor! Just to put an ST70 back in service after sitting somewhere unused for 30 years costs more than the amp cost when new. A 1940s amp might have exotic tubes that are no longer made or are very expensive (since a 1940s amp may not even have octal tubes in it depending on when it was built). Its likely to need more work than an ST70, since a good number of resistors and those dreadful paper and wax capacitors inside will also have to be replaced along with switches and wiring. A lot of those older parts are far more toxic than newer parts- remember PCBs?

But I get the part about keeping stuff out of the waste stream! That is part of why we've had our update-with-warranty-reactivation program for all our products for the last 40 years. But that doesn't keep stuff out of the waste stream- at worst it means a chassis and transformers aren't thrown out along with everything else.

Now days even solid state gear can be so old it needs renovation! I've had to renovate all the synths I play in my band along with some of the effects pedals. Eventually newer class D amps will be so old they will need new filter caps too. If the module fails, depending on who made it it will be repairable, if not, a new module could be installed.

Ralph I’ve still not seen you give any evidence that tube amps are on borrowed time at all other than a list of pros that you seem to see for them. You do seem to be saying that you believe tube amps are ultimately inferior to your class d amp. We all have our distinctly different preferences here and no other amplifier kind seem as polarising.

But as far as tube amps living on borrowed time what actual evidence have you seen happening to make you say that? Where is there any trend evidencing any significant decreased interest or demand for tube amps over these last two decades. There has been many decades to establish class d and to see them actually start to topple all the other toppleologies but where is there significant evidence to show the decline in preferences of the other types despite the easy availability of a range of class d amps? I genuinely just don’t believe it is likely at all and like most audiophiles can easily predict probably not in my life time… since for most of us that’s hardly a very long term crystal ball gaze

Sure some people can’t seem to hear the problem with class d that others seem to be able to but just because you now prefer class d doesn’t mean everyone else are going to want a class d amp. Certainly not till they at least hear one that they believe is worth owning… no matter how cheap (in audiophile terms) they are. I’ve yet to hear one that I have found worth listening to let alone wanting to buy. The class d gan architecture seems sonically more benign than earlier class d but to me I still find them fundamentally unengaging. Yours could be different I guess. But you’ve said there’s other class d amps out there that you like… can you let us know which ones so we could get some benchmark in what you think is good in class d amps other than your own.

I suppose ultimately (and respectfully) Ralph if you do believe there is no good reason for tube amps then why do you continue to sell your tube amps? How long will you continue producing what you seem to believe is now an inferior type of amp? Perhaps shouldn’t you consider making a stand and putting your faith in your current belief and shift to only selling class d amps at some point? I say this not playing devils advocate but simply because I do believe in life perhaps we do need to consider eventually needing to put our money where our mouth is.

 

[Hear Here]

I suppose ultimately (and respectfully) Ralph if you do believe there is no good reason for tube amps then why do you continue to sell your tube amps? How long will you continue producing what you seem to believe is now an inferior type of amp? Perhaps shouldn’t you consider making a stand and putting your faith in your current belief and shift to only selling class d amps at some point?

Isn't that as daft as saying that Ford (after introducing its first electric car) should overnight ditch its petreol and diesel models? Class A and valve amps are endangered species in the same way petrol and diesel cars are? They'll continue for several years but it'll be increasingly seen as anti-social to use them and models will gradually disappear as electric cars (and Class D amps) continue to improve.

 

[the sound of Tao]

Isn't that as daft as saying that Ford (after introducing its first electric car) should overnight ditch its petreol and diesel models? Class A and valve amps are endangered species in the same way petrol and diesel cars are? They'll continue for several years but it'll be increasingly seen as anti-social to use them and models will gradually disappear as electric cars (and Class D amps) continue to improve.

It’s not daft … it’s just a valid question. As a designer (of landscape) I aim wherever I can for best practice in what I do. It’s about choices as designers… it’s not about asking daft (?) questions but rather important ones about our purpose. That said I wouldn’t dump good class a technology for class d technology but if Ralph believes it’s the best kind of amp perhaps that’s what he should do.

As far as antisocial you can’t look at energy use and greenhouse emission just about operational use, it’s about life cycle assessment. If a technology is less energy intensive in operation but greater in creation then that argument is smoke and mirrors in terms of true costs of specification. Total energy use and carbon assessment requires energy and carbon accounting and is a specialist field which is crazy involved but it will be what will need to be used to determine future compliance when the planning for net zero carbon is eventually put in place. I wouldn’t be surprised if a low power SET and high sensitivity speakers turned on only when in use is less resource intensive and energy intensive in a true accounting… and perhaps more fun as well.

 

[Hear Here]

I wouldn’t be surprised if a low power SET and high sensitivity speakers turned on only when in use is less resource intensive and energy intensive in a true accounting

... but still well short of the high sensitivity speakers fed by a sensible-output Class D amp.

I'm pretty certain you'd find that the carbon footprint involved in manufacturing a hand-built tube amp with all its components will be far higher than a typical mass-produced Class D one, or even a hand-tuned one that uses a mass-manufactured Class D module. I applaud Ralph for steering his company in the right direction, though I'm sure it will be a gradual process as consumers lose their unjustified prejudices against modern Class D amps. I accept that all new technologies take a while to develop to the point they match or better older technologies and Class D has reached that stage. As Ralph points out, you can now find a Class D amp that will match the characteristics of any other technology. It just needs the will to search by those who are currently blinkered.

I was an SET advocate (with my horn speakers) for 15 years but 5 years ago I determined to find a solid state amp that would provide at least the same satisfaction factor than the SETs. I bought or home demo'd a dozen amps of all SS technologies and (admittedly to my surprise) I found a Class D the winner.

 

[Solypsa]

Ralph designed and made a class d amp not using an off the shelf module. Isn't that putting ones money in the ring?

 

[Kingrex]

Class D will tickle the elite audiophile's senses when someone makes one really big, heavy and overly powerful with a price tag to match.

 

[the sound of Tao]

... but still well short of the high sensitivity speakers fed by a sensible-output Class D amp.

I'm pretty certain you'd find that the carbon footprint involved in manufacturing a hand-built tube amp with all its components will be far higher than a typical mass-produced Class D one, or even a hand-tuned one that uses a mass-manufactured Class D module. I applaud Ralph for steering his company in the right direction, though I'm sure it will be a gradual process as consumers lose their unjustified prejudices against modern Class D amps. I accept that all new technologies take a while to develop to the point they match or better older technologies and Class D has reached that stage. As Ralph points out, you can now find a Class D amp that will match the characteristics of any other technology. It just needs the will to search by those who are currently blinkered.

I was an SET advocate (with my horn speakers) for 15 years but 5 years ago I determined to find a solid state amp that would provide at least the same satisfaction factor than the SETs. I bought or home demo'd a dozen amps of all SS technologies and (admittedly to my surprise) I found a Class D the winner.

How did you work the carbon footprint out for class d versus that involved for a simple set amp? Is any of that data available or is it just assumption. Some of the most resource intensive elements in production of mainstream contemporary electronics is the production of high tech miniaturised and multi layered and complex parts… I’d be surprised if you did a proper gross energy requirements audit at the embedded creation phase that the high tech based component wouldn’t show itself up as very very intensive but that is just guessing and based on some of the findings on the context of Apple’s research about the associated cost of embedded energy in cutting edge electronics but we won’t know for sure till that level of audit is done.

But that’s what good science is about, actually calculating the whole process to uncover and not using incomplete process and just assuming and relying on green mythology and making sure it isn’t arbitrarily used as evidence in determining how we need to change the way we plan to make things. This has been one of the challenges of us now needing to be developing new ways of thinking and evaluating the real costs of energy consumption and carbon. At this stage we haven’t got a lot of time to start making a difference with all this. We’ve got to get it right at this point as we are already somewhere at the edge of greenhouse planetary boundaries.

 

[Hear Here]

How did you work the carbon footprint out for class d versus that involved for a simple set amp? Is any of that data available or is it just assumption.

Tao - You're really clutching at straws aren't you? You're probably correct to suggest that a thorough audit of the environmental impact of a valve amp’s construction and component inventory vs same with Class D has not been conducted. But just look at the two compared side by side and draw your own (honest) conclusion.

To start with and an obvious give away, is the price comparison. Class D will be a fraction of the tube amp and it's more likely the tube amp builder will not be making a huge margin. Its case will be much bigger with lots of energy cost involved in creating it and the raw materials irequired, similarly the hard wiring inside, the much bigger power transformer (lots of freshly mined copper), etc, etc. The Class D uses far less in materials and, although huge effort goes into development of their component designs, once the chips are designed, I doubt that the small quantities of raw materials (or the energy required to create them) is anywhere near that of the tube amp. A Class D module can be bought for very little money (though these evaluation boards are not best for building high-end kit), they weigh next to nothing and can be easily and without compromise put into the same case and sharing the same power supply as a preamp, DAC and maybe streamer module too. The whole lot weighs in at 10 Kg and much of that is the fancy case that high-end users look for – I’m not suggesting it should be housed in a cardboard box, but food for thought! Compare that using a molecule of imaginative common sense and you can see that the environmental impact of building that box will be a fraction compared with the pile of separates cluttering up tube users racks - and there are none of those heavy and often ridiculously priced copper and / or silver connecting cable and power cords. I rest my case!

 

[the sound of Tao]

Tao - You're really clutching at straws aren't you? You're probably correct to suggest that a thorough audit of the environmental impact of a valve amp’s construction and component inventory vs same with Class D has not been conducted. But just look at the two compared side by side and draw your own (honest) conclusion.

To start with and an obvious give away, is the price comparison. Class D will be a fraction of the tube amp and it's more likely the tube amp builder will not be making a huge margin. Its case will be much bigger with lots of energy cost involved in creating it and the raw materials irequired, similarly the hard wiring inside, the much bigger power transformer (lots of freshly mined copper), etc, etc. The Class D uses far less in materials and, although huge effort goes into development of their component designs, once the chips are designed, I doubt that the small quantities of raw materials (or the energy required to create them) is anywhere near that of the tube amp. A Class D module can be bought for very little money (though these evaluation boards are not best for building high-end kit), they weigh next to nothing and can be easily and without compromise put into the same case and sharing the same power supply as a preamp, DAC and maybe streamer module too. The whole lot weighs in at 10 Kg and much of that is the fancy case that high-end users look for – I’m not suggesting it should be housed in a cardboard box, but food for thought! Compare that using a molecule of imaginative common sense and you can see that the environmental impact of building that box will be a fraction compared with the pile of separates cluttering up tube users racks - and there are none of those heavy and often ridiculously priced copper and / or silver connecting cable and power cords. I rest my case!

Hear hear? Couldn’t explain it more reasonably… I’m talking about proper embodied energy audit not your make it up as you go along. This is hopeless.

 

[Atmasphere]

Ralph I’ve still not seen you give any evidence that tube amps are on borrowed time at all other than a list of pros that you seem to see for them. You do seem to be saying that you believe tube amps are ultimately inferior to your class d amp. We all have our distinctly different preferences here and no other amplifier kind seem as polarising.

But as far as tube amps living on borrowed time what actual evidence have you seen happening to make you say that? Where is there any trend evidencing any significant decreased interest or demand for tube amps over these last two decades. There has been many decades to establish class d and to see them actually start to topple all the other toppleologies but where is there significant evidence to show the decline in preferences of the other types despite the easy availability of a range of class d amps? I genuinely just don’t believe it is likely at all and like most audiophiles can easily predict probably not in my life time… since for most of us that’s hardly a very long term crystal ball gaze

Sure some people can’t seem to hear the problem with class d that others seem to be able to but just because you now prefer class d doesn’t mean everyone else are going to want a class d amp. Certainly not till they at least hear one that they believe is worth owning… no matter how cheap (in audiophile terms) they are. I’ve yet to hear one that I have found worth listening to let alone wanting to buy. The class d gan architecture seems sonically more benign than earlier class d but to me I still find them fundamentally unengaging. Yours could be different I guess. But you’ve said there’s other class d amps out there that you like… can you let us know which ones so we could get some benchmark in what you think is good in class d amps other than your own.

I suppose ultimately (and respectfully) Ralph if you do believe there is no good reason for tube amps then why do you continue to sell your tube amps? How long will you continue producing what you seem to believe is now an inferior type of amp? Perhaps shouldn’t you consider making a stand and putting your faith in your current belief and shift to only selling class d amps at some point? I say this not playing devils advocate but simply because I do believe in life perhaps we do need to consider eventually needing to put our money where our mouth is.

Of course tubes will continue to serve the guitar market for some time to come. But even there class D is making inroads. Last fall we sent a prototype music amplifier to Ron Carter for audition; he's already using a class D amp for his gigs. Weight means a lot to musicians! Last night I did a rock show in Minneapolis and the 30-something guitarist of one of the other bands on the bill was emphatic that if we had a class D guitar amp we'd be very successful (class D guitar amps have been around for a while).

OK- that's not even hifi though, right? It might surprise you that a good number of guitar and in particular bass amps are designed around hifi standards. That's a topic for a different time though.

The things that have kept the tube market alive are twofold: the musical instrument market dominates the use of power tubes and of course home amplifier use, which is a much smaller market.

I've maintained for the last 10-12 years that class D is the rising star in high end audio; ten years ago I also was maintaining that it had not eclipsed any of the prior art including tubes. But things have changed and that statement is no longer true, if pure sonic performance (ignoring the specs for now) is to be the metric. A number of amplifiers are out there that can't be ignored by the community of tube amplifier manufacturers: AGD, Orchard, Purifi (depending greatly on implementation), Class D Audio (that's a company name) to name a few. After we had launched our amplifier a number of customers mentioned to me that they were using some very inexpensive class D amps and were shocked at how good they were. Apparently even with monolithic chips tubes are being rivaled.

If you makes amps of any kind (including any kind of class A amplifier) for a living you ignore these facts at your own peril. Yes, you'll be able to continue selling tube amps for quite some time, because it takes a lot to move anyone off of hallowed concepts they hold (even if fictitious) whether its audio, bicycles or politics. Often the only way they are convinced is direct experience. So many will still want the tube amps even though there are class D amps out there that on 99% of all speakers made will sound better. But as time goes by as a manufacturer you'll find the paint is wet everywhere except the corner in which you reside- the market for tubes will shrink, and for the exact same reason that has kept tubes alive all this time: the sound.

Class D got started on the wrong foot with some really atrocious products 20-25 years ago. I find it amusing that people stick to their old impressions as if they are current, as if somehow technology hasn't improved

I have considered eliminating our smaller OTLs. In time that may happen, but there are still ESLs out there and very few amps that really do them justice. Sound Lab so far as I know has seen fit to install controls in their design (not unlike mid-50s horn speakers in this regard) which allow you to adjust the speaker to the voltage response of the amplifier. So there speakers can be driven with good results with solid state also.

I don't see the point of 'data' in this regard. I've been doing this for a long time. Remember how so many people have said over the years that what you hear at home is what is important? This is one of those situations. I've been playing our OTLs for most of my adult life and we've made improvements which have always been audible over that time. And now we've made another improvement- and I don't miss the tubes at all. I'm sure you can ignore the writing on the wall for now. But it'll get harder and harder to do.

 

[Fishfood]

Someone needs to calculate how big of a solar panel one would need to operate a Class A or Tube amplifier. Panels are getting so cheap and batteries prices will tumble in the coming years as production ramps up. My sister has an electric car and it's only powered by a solar panel.

 

[Solypsa]

If you wanted to, yes, but I can't think of a reason to do that

@Atmasphere If you are up to it, I would love to learn more of your thoughts on this. ( it was your response to Rex about tube first / input stage for class d ). Could start a new thread?

Since this part of the amp is for buffering and gain, are you implying:

1) solid state devices are better for this task ( in a power amp )?

2) your amp isn't designed to need this part of the circuit?

3) Would require more PS voltages and that's a pain?

4) other?

best

Erik

 

[Atmasphere]

@Atmasphere If you are up to it, I would love to learn more of your thoughts on this. ( it was your response to Rex about tube first / input stage for class d ). Could start a new thread?

Since this part of the amp is for buffering and gain, are you implying:

1) solid state devices are better for this task ( in a power amp )?

2) your amp isn't designed to need this part of the circuit?

3) Would require more PS voltages and that's a pain?

4) other?

best

Erik

1) the input of most comparitors is about 2KOhms. That's hard for tubes to drive although our MP-1 preamp can do it with ease. In practice, the important issue is making sure that the input buffer really is transparent and offers no editorial of its own. Oddly, that seems to be a challenge in high end audio- that is why there are so many differing experiences around various off-the-shelf modules!

Opamps can do the job quite well since modern opamps have plenty of Gain Bandwidth Product to prevent the feedback you'll need from causing distortion/coloration of its own. So you can design a buffer with opamps that you simply can't tell is there if you know what you're doing- it only has a gain of 2 so a lot of feedback is used and so worries. So opamps stomp all over tubes in this regard.

2) Our amp uses a comparitor like all class D amps so it needs an input buffer. It accepts both single-ended and balanced inputs with both having an input impedance of 100K- easy to drive with any preamp.

3) Yes, more power supply voltages are needed. We use a converter/regulator that converts from the higher voltages for the output section to the voltages we need. Its not a pain at all, except when supply side shortages cause the part to be not shipping until next March! We think we have enough on hand for now though, and there are other solutions.

4) Another Why You Don't Use A Tube reason: You know, you get this far, the amp works great and everything and then the input tube in the amp has a problem, people swap it out looking for the best sounding example and so on; if you can build a better buffer that is inherently lower distortion and more transparent, without losing any emotional impact and all the other lovely things audiophiles crave, why on earth would you use a tube?? Other than the visual appeal I can't think of a reason. IMO, its a sign that the designer either does not know what he's doing or is intentionally coloring the sound because they think the module isn't musical like it should be.

If me, that's a sign to go back to the drawing board; find out why the module itself doesn't sound musical and fix it! If you do that there will be no need for tubes. If you try to put a bandaid on an amusical module the result will be less transparent and easily superseded.

 

[Hear Here]

My sister has an electric car and it's only powered by a solar panel.

Details please. The only solar-powered cars I know of are university (or similar) projects and totally unsuitable for road use.

 

[Fishfood]

I'm sorry, I should have been more

Details please. The only solar-powered cars I know of are university (or similar) projects and totally unsuitable for road use.

I'm sorry, I should have been more clear. She has an old Nissan Leaf (which you can buy for less than 8K in the US still) that is powered by solar panels on her garage. She's a bit limited on long trips on back to back days since she hasn't purchased an external storage battery yet but with remote work, it's never been an issue.

 

[Hear Here]

That makes more sense! Yes, the Leaf is available here in the UK too and by chance I was reading about it a few days ago. The issue is with charging away from home. The impression given was that Nissan had chosen one method for connecting to the power supply while most other brands use another, more "standard" method. Therefore if you need to charge a Leaf on a long trip, a good deal of planning is required to ensure you can find a charging point that's good for Leaf. However, no doubt your sister is aware of this and probably uses her car solely as a city ruynabout - what it's designed for.

 

[Atmasphere]

Details please. The only solar-powered cars I know of are university (or similar) projects and totally unsuitable for road use.

There was a guy in California who bought his rental electric RAV-4 from Toyota back in the early 2000s. This was just after GM had crushed all the EV-1s (except for one which went to a museum- see 'Who Killed the Electric Car?' documentary). The public ill-will was more than Toyota wanted to deal with so they sold some of the RAV-4s which at the time was their platform to meet the CARB zero-emissions rule of the late 1990s. His home was 100% off-grid and his entire roof and car port roof was solar. He charged his car off grid. As of 2006 and about 160,000 miles the RAV4 still had its 150 mile range - no loss of battery life since new. I know about this as he was featured in an electric car publication back then.

 

[Solypsa]

1) the input of most comparitors is about 2KOhms. That's hard for tubes to drive although our MP-1 preamp can do it with ease. In practice, the important issue is making sure that the input buffer really is transparent and offers no editorial of its own. Oddly, that seems to be a challenge in high end audio- that is why there are so many differing experiences around various off-the-shelf modules!

Opamps can do the job quite well since modern opamps have plenty of Gain Bandwidth Product to prevent the feedback you'll need from causing distortion/coloration of its own. So you can design a buffer with opamps that you simply can't tell is there if you know what you're doing- it only has a gain of 2 so a lot of feedback is used and so worries. So opamps stomp all over tubes in this regard.

2) Our amp uses a comparitor like all class D amps so it needs an input buffer. It accepts both single-ended and balanced inputs with both having an input impedance of 100K- easy to drive with any preamp.

3) Yes, more power supply voltages are needed. We use a converter/regulator that converts from the higher voltages for the output section to the voltages we need. Its not a pain at all, except when supply side shortages cause the part to be not shipping until next March! We think we have enough on hand for now though, and there are other solutions.

4) Another Why You Don't Use A Tube reason: You know, you get this far, the amp works great and everything and then the input tube in the amp has a problem, people swap it out looking for the best sounding example and so on; if you can build a better buffer that is inherently lower distortion and more transparent, without losing any emotional impact and all the other lovely things audiophiles crave, why on earth would you use a tube?? Other than the visual appeal I can't think of a reason. IMO, its a sign that the designer either does not know what he's doing or is intentionally coloring the sound because they think the module isn't musical like it should be.

If me, that's a sign to go back to the drawing board; find out why the module itself doesn't sound musical and fix it! If you do that there will be no need for tubes. If you try to put a bandaid on an amusical module the result will be less transparent and easily superseded.

@Atmasphere I really appreciate your detailed response.

How much of the above reasoning applies to Preamplifiers versus power amp front ends? ( excluding phono for the moment )

 

[Atmasphere]

@Atmasphere I really appreciate your detailed response.

How much of the above reasoning applies to Preamplifiers versus power amp front ends? ( excluding phono for the moment )

Right now I'm not aware of any class D preamps, although we are considering it.

At the preamp level, tubes tend to be much lower distortion than at the power amp level, so the arguments for tube preamps still hold some water. Its no problem getting bandwidth either (which, unless you have an OTL, is definitely a problem on the power amp level).

One of the disadvantages of tubes traditionally has been driving the 600 Ohm balanced lines seen with pro audio equipment. That usually meant an output transformer. We overcame that with several patents (one issued quite recently) and so have tube preamps that drive 600 Ohms no worries, or any higher impedance. So low impedance need not be a particular advantage of solid state in this regard.

At the LOMC phono preamp level, opamps and solid state are traditionally lower noise. This is offset somewhat by tubes having a superior high frequency overload margin which can be significant in avoiding ticks and pops (which can sound like they are on the LP surface).

This also means solid state preamps are more likely to require that 'cartridge loading' resistor, which isn't for the benefit of the cartridge at all, rather the preamp. Its needed because LOMC cartridges in tandem with the tonearm cable produce RFI at some pretty high frequencies, powerful enough to overload many phono stages where the designer didn't take this into account. That's why the addition of the 'loading resistor' helps, because it detunes the resonance that the LOMC cartridge and cable cause, removing the RFI and the distortion it causes. Not saying you can't design a solid state preamp to deal with this RFI properly, but a surprising amount of designers simply don't. I don't know if they aren't aware of it or what. But if you see a 'cartridge loading' switch on the front panel of the preamp its a good bet the designer has no idea why it makes a difference.

So I think tubes at the preamp level will be around a bit longer.

 

[the sound of Tao]

Of course tubes will continue to serve the guitar market for some time to come. But even there class D is making inroads. Last fall we sent a prototype music amplifier to Ron Carter for audition; he's already using a class D amp for his gigs. Weight means a lot to musicians! Last night I did a rock show in Minneapolis and the 30-something guitarist of one of the other bands on the bill was emphatic that if we had a class D guitar amp we'd be very successful (class D guitar amps have been around for a while).

OK- that's not even hifi though, right? It might surprise you that a good number of guitar and in particular bass amps are designed around hifi standards. That's a topic for a different time though.

The things that have kept the tube market alive are twofold: the musical instrument market dominates the use of power tubes and of course home amplifier use, which is a much smaller market.

I've maintained for the last 10-12 years that class D is the rising star in high end audio; ten years ago I also was maintaining that it had not eclipsed any of the prior art including tubes. But things have changed and that statement is no longer true, if pure sonic performance (ignoring the specs for now) is to be the metric. A number of amplifiers are out there that can't be ignored by the community of tube amplifier manufacturers: AGD, Orchard, Purifi (depending greatly on implementation), Class D Audio (that's a company name) to name a few. After we had launched our amplifier a number of customers mentioned to me that they were using some very inexpensive class D amps and were shocked at how good they were. Apparently even with monolithic chips tubes are being rivaled.

If you makes amps of any kind (including any kind of class A amplifier) for a living you ignore these facts at your own peril. Yes, you'll be able to continue selling tube amps for quite some time, because it takes a lot to move anyone off of hallowed concepts they hold (even if fictitious) whether its audio, bicycles or politics. Often the only way they are convinced is direct experience. So many will still want the tube amps even though there are class D amps out there that on 99% of all speakers made will sound better. But as time goes by as a manufacturer you'll find the paint is wet everywhere except the corner in which you reside- the market for tubes will shrink, and for the exact same reason that has kept tubes alive all this time: the sound.

Class D got started on the wrong foot with some really atrocious products 20-25 years ago. I find it amusing that people stick to their old impressions as if they are current, as if somehow technology hasn't improved

I have considered eliminating our smaller OTLs. In time that may happen, but there are still ESLs out there and very few amps that really do them justice. Sound Lab so far as I know has seen fit to install controls in their design (not unlike mid-50s horn speakers in this regard) which allow you to adjust the speaker to the voltage response of the amplifier. So there speakers can be driven with good results with solid state also.

I don't see the point of 'data' in this regard. I've been doing this for a long time. Remember how so many people have said over the years that what you hear at home is what is important? This is one of those situations. I've been playing our OTLs for most of my adult life and we've made improvements which have always been audible over that time. And now we've made another improvement- and I don't miss the tubes at all. I'm sure you can ignore the writing on the wall for now. But it'll get harder and harder to do.

It’s frustrating to see how little sustainability in design is still understood by the market and by many within industry. I’ve been developing training for sustainability in design for the last 14 years. People look to high tech as the solution to everything without understanding the resource and energy implications of producing high tech can make it unsustainable in the big picture.

Crystal ball gazing is difficult but having data helps reduce people’s uninformed fantasy passing for fact. That’s why it’s important to evidence rather than assume. In the end the consumption model will clearly need to change and the hidden costs of consumption will need to be factored in what will most likely be a user pays model. All the figures talked about cost here will change because they will be assessed in the future light of life cycle assessment and accounting for true cost of manufacture.

Things will get more expensive quite quickly once the implications of net zero carbon requirements and legislation take hold. If the production phase and end of life phases are more properly costed then the economic realities will be very different and will change the way the future plays out in this market going forwards.

Amusicality seems to be the archilles heel of class d technology and so music lovers and musicians may continue to avoid it if they continue to find it unsatisfying. Spending anything on something that doesn’t fit the fundamental needs of purpose becomes ultimately a waste. In a lo-fi and mid-fi market there’s probably less challenges to a functionally amusical amplifier but it’d make sense that class d may stay a niche product at the high end and for professional gear for people who are music lovers and are sensitive to that essential difference.