Allen Wright (Vacuum State Electronics) is really the only one I know of that will be selling them, though I'm not sure they're avialable quite yet. He's doing differential circuits with solid-state current sinks.
The big leader in this field has been Lynn Olson, you can find info on his amplifiers here: http://www.nutshellhifi.com/triode1.html He doesn't sell anything though. His webpage is amazing, look at everything. I don't think there's anyone that knows this stuff better. He generally promotes 'normal' push-pull over differential because the output tubes are in parallel instead of series then.
Gary Pimm has been working on some push-pull stuff as well. (Just google his name) He did a differential all-pentode amp that achieves something like 10hz - 100 khz flat, limited by the output transformer. OH and it also sounds pretty good too:)
I think K&K audio has been fiddling with push-pull class A triodes too but nothing available yet.
It's funny to say this is 'cutting edge' since it's really like 60-70 years old, but the revival of this stuff is very recent (2-3 years). Previous to that SET dominated all tube sales. I imagine in the next 3 years or so we'll see more commercial products. The first ones will be from Allen I expect though.
Things were looking bleak for tubes, but between this excitement, and the fact that some REALLY good tubes are coming out of China these days (TianJin/FullMusic 300B's, 2A3's, and even 45's current production are awesome)... well, things are looking up.
Prove what exactly? That tubes are lower distortion? Just look at the curves...
It's easy to try to make it a Tubes vs Transistors argument, but it's never that simple.
Tubes are big, hot, sometimes noisy, inefficient, but above all else, they are profoundly linear devices.
Transistors are EXTREMELY nonlinear. They cannot compete with tubes for distortion without feedback.
So the whole tubes vs transistors debate ends up intertwined with the feedback vs no feedback debate. A lot of the time people will be comparing Single Ended Triode amplifiers to push-pull or differential solid state amplifiers with global negative feedback. Add in the differences in power supplies, and the amps are so incredibly dissimilar that to take it as a basis for comparison between tubes & transistors is insanity.
You can build push-pull tube amps that don't sound 'warm' can compete in terms of power output (for moderately efficient speakers 93db+) and yet have a SLEW of advantages over solid state. Like: No feedback, very short current loops around each stage, orders of magnitude lower high freq noise from the power supply.
You can build solid state amps without feedback (see the Zen) they operate pure Class A single-ended and nonsurprisingly share many things in common with tubes, like inefficiency, high second order distortion, moderate output impedance, and so on... BUT, of note, it will have higher distortion than a tube:)
Really it comes down to implementation, you can make very good amps with both, and very bad amps with both.
When you try to go for high power and use feedback to achieve it with high-distortion output devices (like tetrodes or any transistor) you tend to do better with solid state because of the higher gain allowing more feedback. Well, that is to say, you tend to MEASURE better on very simple measurements like THD (probably the LEAST audible of all the things you could gauge.) But this is what 99% of amplifiers sold are and some do sound OK.
When you go start to go towards Class A and no feedback or low feedback, tubes (particularly the directly heated triodes) really start to show thier colors. Thier linearity, and the fact that they run at high voltage and low current, lets you accomplish things that simply cannot be done with transistors.
Tubes have come a long way as well. Deep Class-A push pull tube amplifiers have very low distortion, zero feedback, very tight & controlled current loops, moderate power (20-30 watts), very low power supply noise, and most importantly, stunning sound.
They also utterly lack the 'warmth' normally associated with tubes, and yet still totally avoid the problems of solid state and negative feedback.
There's been an incredible amount of progress made in the last 2-3 years on these kinds of amplifiers.
Please stop spreading this nonsense. The vast majority of tubes have MUCH lower distortion than any solid state device. In fact the big DHT's (300B, 845) are probably the lowest distortion amplification devices ever made. Look at the curves if you don't believe me. Tubes at least look VAGUELY linear, transistors most certainly do not.
Solid state competes only by having very high gain and using feedback. There is absolutely no way for solid state devices to compete with tubes in terms of distortion in the forward path.
And feedback has a whole bunch of fun problems. It's great when you're driving resistors or simplified R/L/C 'dummy speakers'... but it has real problems when you drive REAL speakers. Real speakers have dozens of resonances all over the frequency range that throw all kinds of garbage back at the amplifier. Feedback has to take this trash and RE-AMPLIFY THE GARBAGE in order to cancel it out and present a lower output impedance.
With tubes (especially push-pull transformer-coupled tube amplifiers running heavy Class A) you can achieve VERY low distortion numbers with no feedback whatsoever. You do require speakers of higher-efficiency of course, but this is not hard to do. There are very good-sounding speakers in the 95db/watt range and up that can run great on tube amps in the 16w range. Horns up around 100db/watt are happy with much less.
Yes, SOME tube amps sound very 'warm' and distorted, but quite frankly, that was 5 years ago. Things have come a long way. Class A push-pull is really taking off and people are achieving EXTREMELY fast, detailed, low distortion tube amps that have all kinds of advantages over solid state.
What they did was, create tight loops performing the same operation over and over. And found that different operations tend to result in different sorts of noise on the power supply, resulting in different sounds from the capacitors.
Remember though with their 96,000 Hz sampling rate, a 1 Ghz CPU performs over 10,000 instructions per sample.
Air does not vibrate fast enough, and there are no microphones with frequency response high enough to let you look at individual operations.
So I guess, if you knew the characteristics well enough, you could record the sound of the capacitors and say 'Hey, this guy is running GnuPG' on it. I don't see a concievable way to figure out the keys and this article doesn't suggest one.
The important question is exactly what is "Real-Time." Broadly, I would see this as 'a sequence of computations that must be performed on data with a fixed amount of latency'. Often, we are talking about streams of data, and want low latency. There are two common reasons for needing low latency: 1) To have the data ready in time for a synchronous communication protocol, and 2) Because fast response based on the data is neccesary, such as with robotic control systems.
Depending on how much you need to do, ANY processor can give respectable real-time performance. Certain processors might lend themselves to better timing predictability & lower latency while still offering excellent floating point performance. A perfect example would be Sun's new MAJC, which is designed pretty much from the ground up for low-latency streaming computation.
As for the Pentium / Athlon matter, it's not so much the processor, it's the PC architecture. The PC (most notably the PCI bus) isn't really meant for working on streams of data, and timing can be completely unpredictable, depending on which devices have pending interrupts. If you take the Pentium & Athlon out of the PC architecture, I would expect one could achieve much better real-time performance. But I know of very few architectures for the Pentium, and none for the Athlon, so I expect a real comparison is impossible at this time.
Also, multiprocessing has been mentioned repeatedly. There are two ways to increase real-time performance with multiprocessors. They can be connected in parallel and series. Each has drawbacks. Parallel can complicate programming & design, and is only really effective if the computations lend themselves to it. Serial connection would almost always be possible, but at the cost of latency.
The simple answer is that the best real-time processor is the cheapest one that meets the needs of that particular application.
This is actually a really good idea. (Not the dissolving discs, but what Jbrecken said.) If it were easy to tell whether a disc had been used, then perhaps stores could accept returns again?
mWorld has quite a few screenshots. Click on 'Games' up at the top, and then, on the list, click on the little smileys for a review of the game, many of them have screenshots. (Look for happy smileys, as those are probably the nicer games.) Dr W.
Re:This kind of thing has existed for a while
on
Verge2 GPLed
·
· Score: 1
True, while MegaZeux is a bit more campy than Verge, it has a wider range. There have been RPGs, Platform Games, Puzzle Games, Adventure Games, etc... for MZX.
MegaZeux started out as a shareware game taking after Epic Megagames ZZT. It is still ASCII-based, yet allows you to edit the characters & the color tiles. It has also benefited greatly from being open sourced, as you can imagine, from being an old EMS-based DOS game.
It has been a lot of fun to work on development (mainly, new features that will be implemented once the new codebase comes out), almost as much fun as making games for it.
Of course, the more software that's available for the Alpha architecture, the better. I think this software is so cheap because UNIX isn't as important as it used to be. My understanding was that UNIX had an edge over linux on these systems because of its highly-optimised, closed-source compilers.
It is also my understanding that the libraries/compilers/etc.. needed are being developed for linux, so perhaps it will be more usefull for scientific applications.
As for the comment made above about whether the Alpha is still the fastest, It is the fastest not just because of the processor, but the EV6 bus. For total system throughput, I don't know of anything that even challenges the Alpha.
First off, while I don't think that all discrete logic and analog ICs will move towards this type of packaging, it definitely is the trend for newer chips of every type.
I've been a home hardware hacker for seven years or so, and I've seen things get a lot better, and a lot worse in different respects.
While it's easier than ever to get information about chips online now, with almost every electronics company offering datasheets in.pdf form for download, a lot of this information is misleading. Companies like motorola have dozens of products listed, with full specs and information, and yet the product isn't in sampling yet.
As for actual hardware hacking, personally, I don't think it's too bad. It's just a question of what you're trying to do. Microcontrollers, discrete logic, and analog ICs are all still available in DIP (pin) packages and can be thrown together on a breadboard.
But as for high-speed digital design, this is simply out of the range of most home experimenters. There is a lot more too it than just finding a free/cheap PCB cad program (which do exist, try www.cadsoftusa.com), and a socket for that BGA processor (www.emulation.com). Not only is it next to impossible to make the multi-layer PCBs which are needed for these designs, but only the most expensive PCB software packages can help you keep track of the timing requirements for these systems.
The hardware hacker isn't dead, he just is shut out from moving upwards with the rest of technology.
I'm hoping to start a web page soon to help the hardware hacker who wants to move on to higher-speed and more complex systems.
Slashdot Mirror
Allen Wright (Vacuum State Electronics) is really the only one I know of that will be selling them, though I'm not sure they're avialable quite yet. He's doing differential circuits with solid-state current sinks.
The big leader in this field has been Lynn Olson, you can find info on his amplifiers here: http://www.nutshellhifi.com/triode1.html He doesn't sell anything though. His webpage is amazing, look at everything. I don't think there's anyone that knows this stuff better. He generally promotes 'normal' push-pull over differential because the output tubes are in parallel instead of series then.
Gary Pimm has been working on some push-pull stuff as well. (Just google his name) He did a differential all-pentode amp that achieves something like 10hz - 100 khz flat, limited by the output transformer. OH and it also sounds pretty good too
I think K&K audio has been fiddling with push-pull class A triodes too but nothing available yet.
It's funny to say this is 'cutting edge' since it's really like 60-70 years old, but the revival of this stuff is very recent (2-3 years). Previous to that SET dominated all tube sales. I imagine in the next 3 years or so we'll see more commercial products. The first ones will be from Allen I expect though.
Things were looking bleak for tubes, but between this excitement, and the fact that some REALLY good tubes are coming out of China these days (TianJin/FullMusic 300B's, 2A3's, and even 45's current production are awesome)... well, things are looking up.
Prove what exactly? That tubes are lower distortion? Just look at the curves...
:)
It's easy to try to make it a Tubes vs Transistors argument, but it's never that simple.
Tubes are big, hot, sometimes noisy, inefficient, but above all else, they are profoundly linear devices.
Transistors are EXTREMELY nonlinear. They cannot compete with tubes for distortion without feedback.
So the whole tubes vs transistors debate ends up intertwined with the feedback vs no feedback debate. A lot of the time people will be comparing Single Ended Triode amplifiers to push-pull or differential solid state amplifiers with global negative feedback. Add in the differences in power supplies, and the amps are so incredibly dissimilar that to take it as a basis for comparison between tubes & transistors is insanity.
You can build push-pull tube amps that don't sound 'warm' can compete in terms of power output (for moderately efficient speakers 93db+) and yet have a SLEW of advantages over solid state. Like: No feedback, very short current loops around each stage, orders of magnitude lower high freq noise from the power supply.
You can build solid state amps without feedback (see the Zen) they operate pure Class A single-ended and nonsurprisingly share many things in common with tubes, like inefficiency, high second order distortion, moderate output impedance, and so on... BUT, of note, it will have higher distortion than a tube
Really it comes down to implementation, you can make very good amps with both, and very bad amps with both.
When you try to go for high power and use feedback to achieve it with high-distortion output devices (like tetrodes or any transistor) you tend to do better with solid state because of the higher gain allowing more feedback. Well, that is to say, you tend to MEASURE better on very simple measurements like THD (probably the LEAST audible of all the things you could gauge.) But this is what 99% of amplifiers sold are and some do sound OK.
When you go start to go towards Class A and no feedback or low feedback, tubes (particularly the directly heated triodes) really start to show thier colors. Thier linearity, and the fact that they run at high voltage and low current, lets you accomplish things that simply cannot be done with transistors.
Tubes have come a long way as well. Deep Class-A push pull tube amplifiers have very low distortion, zero feedback, very tight & controlled current loops, moderate power (20-30 watts), very low power supply noise, and most importantly, stunning sound.
They also utterly lack the 'warmth' normally associated with tubes, and yet still totally avoid the problems of solid state and negative feedback.
There's been an incredible amount of progress made in the last 2-3 years on these kinds of amplifiers.
Please stop spreading this nonsense. The vast majority of tubes have MUCH lower distortion than any solid state device. In fact the big DHT's (300B, 845) are probably the lowest distortion amplification devices ever made. Look at the curves if you don't believe me. Tubes at least look VAGUELY linear, transistors most certainly do not.
Solid state competes only by having very high gain and using feedback. There is absolutely no way for solid state devices to compete with tubes in terms of distortion in the forward path.
And feedback has a whole bunch of fun problems. It's great when you're driving resistors or simplified R/L/C 'dummy speakers'... but it has real problems when you drive REAL speakers. Real speakers have dozens of resonances all over the frequency range that throw all kinds of garbage back at the amplifier. Feedback has to take this trash and RE-AMPLIFY THE GARBAGE in order to cancel it out and present a lower output impedance.
With tubes (especially push-pull transformer-coupled tube amplifiers running heavy Class A) you can achieve VERY low distortion numbers with no feedback whatsoever. You do require speakers of higher-efficiency of course, but this is not hard to do. There are very good-sounding speakers in the 95db/watt range and up that can run great on tube amps in the 16w range. Horns up around 100db/watt are happy with much less.
Yes, SOME tube amps sound very 'warm' and distorted, but quite frankly, that was 5 years ago. Things have come a long way. Class A push-pull is really taking off and people are achieving EXTREMELY fast, detailed, low distortion tube amps that have all kinds of advantages over solid state.
What they did was, create tight loops performing the same operation over and over. And found that different operations tend to result in different sorts of noise on the power supply, resulting in different sounds from the capacitors.
Remember though with their 96,000 Hz sampling rate, a 1 Ghz CPU performs over 10,000 instructions per sample.
Air does not vibrate fast enough, and there are no microphones with frequency response high enough to let you look at individual operations.
So I guess, if you knew the characteristics well enough, you could record the sound of the capacitors and say 'Hey, this guy is running GnuPG' on it. I don't see a concievable way to figure out the keys and this article doesn't suggest one.
The important question is exactly what is "Real-Time." Broadly, I would see this as 'a sequence of computations that must be performed on data with a fixed amount of latency'. Often, we are talking about streams of data, and want low latency. There are two common reasons for needing low latency: 1) To have the data ready in time for a synchronous communication protocol, and 2) Because fast response based on the data is neccesary, such as with robotic control systems.
Depending on how much you need to do, ANY processor can give respectable real-time performance. Certain processors might lend themselves to better timing predictability & lower latency while still offering excellent floating point performance. A perfect example would be Sun's new MAJC, which is designed pretty much from the ground up for low-latency streaming computation.
As for the Pentium / Athlon matter, it's not so much the processor, it's the PC architecture. The PC (most notably the PCI bus) isn't really meant for working on streams of data, and timing can be completely unpredictable, depending on which devices have pending interrupts. If you take the Pentium & Athlon out of the PC architecture, I would expect one could achieve much better real-time performance. But I know of very few architectures for the Pentium, and none for the Athlon, so I expect a real comparison is impossible at this time.
Also, multiprocessing has been mentioned repeatedly. There are two ways to increase real-time performance with multiprocessors. They can be connected in parallel and series. Each has drawbacks. Parallel can complicate programming & design, and is only really effective if the computations lend themselves to it. Serial connection would almost always be possible, but at the cost of latency.
The simple answer is that the best real-time processor is the cheapest one that meets the needs of that particular application.
Doctor Wonky
This is actually a really good idea. (Not the dissolving discs, but what Jbrecken said.) If it were easy to tell whether a disc had been used, then perhaps stores could accept returns again?
Dr W.
I believe that they have been in 2.3 since 2.3.13 Dr W
mWorld has quite a few screenshots. Click on 'Games' up at the top, and then, on the list, click on the little smileys for a review of the game, many of them have screenshots. (Look for happy smileys, as those are probably the nicer games.) Dr W.
True, while MegaZeux is a bit more campy than Verge, it has a wider range. There have been RPGs, Platform Games, Puzzle Games, Adventure Games, etc... for MZX.
MegaZeux started out as a shareware game taking after Epic Megagames ZZT. It is still ASCII-based, yet allows you to edit the characters & the color tiles. It has also benefited greatly from being open sourced, as you can imagine, from being an old EMS-based DOS game.
It has been a lot of fun to work on development (mainly, new features that will be implemented once the new codebase comes out), almost as much fun as making games for it.
Dr w.
I especially like this:
"...the few who don't like to think about sex, at least not officially."
How do you officially think about sex?
Doc
Of course, the more software that's available for the Alpha architecture, the better. I think this software is so cheap because UNIX isn't as important as it used to be. My understanding was that UNIX had an edge over linux on these systems because of its highly-optimised, closed-source compilers.
It is also my understanding that the libraries/compilers/etc.. needed are being developed for linux, so perhaps it will be more usefull for scientific applications.
As for the comment made above about whether the Alpha is still the fastest, It is the fastest not just because of the processor, but the EV6 bus. For total system throughput, I don't know of anything that even challenges the Alpha.
Dr. W
First off, while I don't think that all discrete logic and analog ICs will move towards this type of packaging, it definitely is the trend for newer chips of every type.
I've been a home hardware hacker for seven years or so, and I've seen things get a lot better, and a lot worse in different respects.
While it's easier than ever to get information about chips online now, with almost every electronics company offering datasheets in
As for actual hardware hacking, personally, I don't think it's too bad. It's just a question of what you're trying to do. Microcontrollers, discrete logic, and analog ICs are all still available in DIP (pin) packages and can be thrown together on a breadboard.
But as for high-speed digital design, this is simply out of the range of most home experimenters. There is a lot more too it than just finding a free/cheap PCB cad program (which do exist, try www.cadsoftusa.com), and a socket for that BGA processor (www.emulation.com). Not only is it next to impossible to make the multi-layer PCBs which are needed for these designs, but only the most expensive PCB software packages can help you keep track of the timing requirements for these systems.
The hardware hacker isn't dead, he just is shut out from moving upwards with the rest of technology.
I'm hoping to start a web page soon to help the hardware hacker who wants to move on to higher-speed and more complex systems.
Dr Wonky