Test Electrix said:
Great application! Those guys just love hauling heavy equipment that puts out tons of heat to venues that have questionable mains power. Don't forget to build a spare! Hmmm, I wonder what happens when a beer gets spilled on 1KV+ power supply? Hmmm...
In all seriousness, reading your posts, if someone told me that you were either a seasoned tech or engineer, or were 14 years old, I would no problem believing either!
..........It's intended to be used for DJs, bands etc ...........
Ho-Hum.....
And, you think they are gonna be happy lugging round 50-100Kg of power-amp for each and every gig!!??
--Especially as their 1kW MOSFET amp doesnt mind being slung in the back of a van, bumped half-way round the country....And, they are USED to this sort of performance from an amp, and treat it as such--Unlike years ago where amps were treated somewhat more carefully due to the valves and their delicacy...
And the above MOSFET amp doesnt produce the distortion you're so worried about--But sounds 'lifeless' probably because of it....
Some 'distortions' are what give valve-amps that particular sound--If you want sub .00 distortion, Stick to Sand.......
Nah, To me, this project is not viable either for just yourself, and Definitely Not a Commercial proposition!
Ho-Hum.....
And, you think they are gonna be happy lugging round 50-100Kg of power-amp for each and every gig!!??
--Especially as their 1kW MOSFET amp doesnt mind being slung in the back of a van, bumped half-way round the country....And, they are USED to this sort of performance from an amp, and treat it as such--Unlike years ago where amps were treated somewhat more carefully due to the valves and their delicacy...
And the above MOSFET amp doesnt produce the distortion you're so worried about--But sounds 'lifeless' probably because of it....
Some 'distortions' are what give valve-amps that particular sound--If you want sub .00 distortion, Stick to Sand.......
Nah, To me, this project is not viable either for just yourself, and Definitely Not a Commercial proposition!
Sorry I need to more specific... Single-ended class A
And as for logistics I'll sort a chassis when I've decided on what valve I'm going to use, it'll definitely incorporate anti-shock mounting and make it easily transportable. I am only asking if anyone could reccomend some 'ridiculously powerful triodes', everything else I can sort out on my own
And as for logistics I'll sort a chassis when I've decided on what valve I'm going to use, it'll definitely incorporate anti-shock mounting and make it easily transportable. I am only asking if anyone could reccomend some 'ridiculously powerful triodes', everything else I can sort out on my own
Test Electrix said:Sorry I need to more specific... Single-ended class A
And as for logistics I'll sort a chassis when I've decided on what valve I'm going to use, it'll definitely incorporate anti-shock mounting and make it easily transportable. I am only asking if anyone could reccomend some 'ridiculously powerful triodes', everything else I can sort out on my own
Here is some sanity restoring reality:
You do not know how to go about this. It will not work. It is NOT as simple as finding a "ridiculously powerful triode".
.........Couple of hundred watts......
.......Single-ended, Class A.....
Well, IF I was gonna do something as daft as this, I would look at two, maybe 3 parallel 833A, Power-Drive (Tubelab style) preceded by a GOOD voltage gain stage-or two!!...
That however, is the Simple part!!
As to PSU and o/p transformer, These would Have to be specially made.
I should imagine a SE 200W transformer would weigh around 25Kg, maybe more, and be pretty poor in performance unless VERY carefully designed and made. I have NO idea who would undertake such a task...
The PU and its transformer could I guess be raided from summit like an X Ray machineor ome other high voltage/power device--Check out the 'Coilers' --see what they use....
Due to the weight of thi lot, I would think of separate chassis for PSU and amp, with ome SERIOUS interlocking for safety reasons. The voltages you'll need are extreme--even for those used to very high voltages....
The VERY BEST of luck. You are gonna need it!!
.......Single-ended, Class A.....
Well, IF I was gonna do something as daft as this, I would look at two, maybe 3 parallel 833A, Power-Drive (Tubelab style) preceded by a GOOD voltage gain stage-or two!!...
That however, is the Simple part!!
As to PSU and o/p transformer, These would Have to be specially made.
I should imagine a SE 200W transformer would weigh around 25Kg, maybe more, and be pretty poor in performance unless VERY carefully designed and made. I have NO idea who would undertake such a task...
The PU and its transformer could I guess be raided from summit like an X Ray machineor ome other high voltage/power device--Check out the 'Coilers' --see what they use....
Due to the weight of thi lot, I would think of separate chassis for PSU and amp, with ome SERIOUS interlocking for safety reasons. The voltages you'll need are extreme--even for those used to very high voltages....
The VERY BEST of luck. You are gonna need it!!
Test Electrix said:
No. Class A does not mean even order harmonic reproduction. And it does not mean even order harmonic generation. It is the same as to say, "4-stroke engine in a mini VAN = a football team reproduction (as well as rugby, and therefore a better reproduction of the game being played by them)".
I agree. It's possible, but finding the tubes for the job isn't the hard part. Bandwidth, pallet jack, air conditioning, resistive losses in the supplying electrical system, are things that come to mind. An amplifier with a class A or AB, PP output stage can give a similar harmonic spectra to that of an SE amplifier. It just needs a single ended input stage and a little tweaking. Class-A PP is just as inefficient as SE, just your output iron would be smaller, distortion is less, and tenancies of wider bandwidth (at these power levels). I'd do a class AB if those power levels are desired.
Jeb-D. said:
An amplifier with a class A or AB, PP output stage can give a similar harmonic spectra to that of an SE amplifier. It just needs a single ended input stage and a little tweaking. Class-A PP is just as inefficient as SE, just your output iron would be smaller, distortion is less, and tenancies of wider bandwidth (at these power levels). I'd do a class AB if those power levels are desired.
I hope we haven't frightened him off, It would be interesting to see if he did make this device and how he overcomes the major issue he'll encounter.....
Alastair E said:
hey-Hey!!!,
However, I am still a PP Class A builder, and like decent output power...and am a firm believer in single-pair power stages. More power means more dissipation, so bring on the 813's...
(already running 5-125B )Big project design will teach much about discovering limits/limitations of expanding the 'usual' audio designs.
cheers,
Douglas
This one isn't going to happen. Why?
OK, this is doable, I have cranked 200 watts out of an 833A in SE class A2. I paid a well respected transformer winder a good bit of money for a custom OPT. It was the weakest link in the amplifier. The HF response was compromized by the sheer size of the thing. The prototype ran on 1500 volts and consumed 300 to 500 mA. Not for inexperienced builders.
Well you might get to 0.1% distortion with a big bunch of NFB, but then why would you go SE. So you could go for a pair of 833A's (or other suitable tubes) in P-P, make 400 watts in class A, but again serious NFB would be needed to get to 0.1%, and the OPT would again be the limiting factor. There is no textbook design for this, like most really big tube amps, a bunch of experiments, data taking and itterative design will be needed. It is inevitable that some parts will be sacrificed to the fire gods here. It takes experience to minimize blown parts and collateral damage.
This make sense. You aren't going to get to "100-500wat" without big transmitting tubes, big sweep tubes, or multiple big audio tubes like the KT88.
100 - 500 watt OTL, with transmitting tubes? No, guys this isn't happening. It seems that the poster does not have a full understanding of vacuum tube design, the costs and risks involved.
An amplifier of this caliber should not be attempted by someone that hasn't built several smaller designs, and has a full understanding of what is happening. A 100 to 500 watt OTL will see average current capability in the 7 amp range with 10 to 15 AMP peaks. This implies a bunch of tubes in parallel, and means of keeping them somewhat balanced. The Atmasphere is a class AB design and it is at best 10% efficient. A true class A OTL would be far worse off. Power consumption would be in the 5KW range. Thermal management will be considerable just to keep it from catching fire! The cost of components for the final design WILL be in the multi kilobuck range, and that is not counting the parts that will inevitably be fried to make it all work.
I am all for building big amps, even though I shelved the 200 Watt 833A SE for practicality reasons. I will be working on a 200+ watt per channel push pull amp once I get some other projects out of the way. I have been building tube amps on and off for about 40 years, and I realize that this is far more difficult than the typical 50 WPC stereo of ear shredding guitar amp. I have been testing subcircuits for this amp for nearly 2 years, and I am still not ready to build it. I plan for about 50 watts in class A (unknown yet) but operation in the 200+ watt range must be in AB just for efficiency. Several efficiency enhancements are planned, but not functional yet.
OK, this is doable, I have cranked 200 watts out of an 833A in SE class A2. I paid a well respected transformer winder a good bit of money for a custom OPT. It was the weakest link in the amplifier. The HF response was compromized by the sheer size of the thing. The prototype ran on 1500 volts and consumed 300 to 500 mA. Not for inexperienced builders.
Well you might get to 0.1% distortion with a big bunch of NFB, but then why would you go SE. So you could go for a pair of 833A's (or other suitable tubes) in P-P, make 400 watts in class A, but again serious NFB would be needed to get to 0.1%, and the OPT would again be the limiting factor. There is no textbook design for this, like most really big tube amps, a bunch of experiments, data taking and itterative design will be needed. It is inevitable that some parts will be sacrificed to the fire gods here. It takes experience to minimize blown parts and collateral damage.
This make sense. You aren't going to get to "100-500wat" without big transmitting tubes, big sweep tubes, or multiple big audio tubes like the KT88.
100 - 500 watt OTL, with transmitting tubes? No, guys this isn't happening. It seems that the poster does not have a full understanding of vacuum tube design, the costs and risks involved.
An amplifier of this caliber should not be attempted by someone that hasn't built several smaller designs, and has a full understanding of what is happening. A 100 to 500 watt OTL will see average current capability in the 7 amp range with 10 to 15 AMP peaks. This implies a bunch of tubes in parallel, and means of keeping them somewhat balanced. The Atmasphere is a class AB design and it is at best 10% efficient. A true class A OTL would be far worse off. Power consumption would be in the 5KW range. Thermal management will be considerable just to keep it from catching fire! The cost of components for the final design WILL be in the multi kilobuck range, and that is not counting the parts that will inevitably be fried to make it all work.
I am all for building big amps, even though I shelved the 200 Watt 833A SE for practicality reasons. I will be working on a 200+ watt per channel push pull amp once I get some other projects out of the way. I have been building tube amps on and off for about 40 years, and I realize that this is far more difficult than the typical 50 WPC stereo of ear shredding guitar amp. I have been testing subcircuits for this amp for nearly 2 years, and I am still not ready to build it. I plan for about 50 watts in class A (unknown yet) but operation in the 200+ watt range must be in AB just for efficiency. Several efficiency enhancements are planned, but not functional yet.
Okay to be honest I don't know the most about valves or have much experience with them so I'm going through several other stages of development on the way and several different designs. I DO want even order harmonics present and some mentioned they can still be reproduced A/B but I thought even orders got cancelled out by the split driver phasing
If you are right sir you may well have saved me a lot of time and effort! I think a smaller 200-400 watt (tri-amped with bass crossover at 350hz using data for 'typical program material' basis from a Fane manual quoted here using a 50/50 split proportions of power distribution between bass and mid-treble) system may be in order may be the first 'leaping point', enough for a hall or large-ish room maybe.
Oh yeah thankyou for the responses, ALL this feedback is ridiculously helpful and I never thought I'd get so much!
Sorry, also it's not necessarily about power so much as being loud, detailed and warm. I was thinking something for a field or hall say
If you are right sir you may well have saved me a lot of time and effort! I think a smaller 200-400 watt (tri-amped with bass crossover at 350hz using data for 'typical program material' basis from a Fane manual quoted here using a 50/50 split proportions of power distribution between bass and mid-treble) system may be in order may be the first 'leaping point', enough for a hall or large-ish room maybe.
Oh yeah thankyou for the responses, ALL this feedback is ridiculously helpful and I never thought I'd get so much!
Sorry, also it's not necessarily about power so much as being loud, detailed and warm. I was thinking something for a field or hall say
Its not about even orders.
Its not about even orders.
Its not about even orders.
And let me repeat!
Its about low orders, and masking IMD.
Odd orders are just as important.
(Diatonic Octave) 2nd Harmonic more important than 3rd
(Diatonic Fifth) 3rd Harmonic more important then 4th
All harmonics, even or odd are musically related to the root.
IMD (sum and difference products) are almost certainly not.
But the mind and ear have limited
signal processing capabilities.
We tend to reference everything else we
hear to the root tones that are lowest,
loudest, or heard first. And can only track
so many.
The very reason an MP3 can throw away
so much music, and most kids don't even
notice whats missing. It would normally
have been masked by our brain anyway.
So the trick is to make an amp that hides
the onset of clipping and inevitable IMD.
Overwhelming us with stuff that we might
misinterpret as musical, rather than the
unrelated noise.
All in reasonable moderation of course.
Its not about even orders.
Its not about even orders.
And let me repeat!
Its about low orders, and masking IMD.
Odd orders are just as important.
(Diatonic Octave) 2nd Harmonic more important than 3rd
(Diatonic Fifth) 3rd Harmonic more important then 4th
All harmonics, even or odd are musically related to the root.
IMD (sum and difference products) are almost certainly not.
But the mind and ear have limited
signal processing capabilities.
We tend to reference everything else we
hear to the root tones that are lowest,
loudest, or heard first. And can only track
so many.
The very reason an MP3 can throw away
so much music, and most kids don't even
notice whats missing. It would normally
have been masked by our brain anyway.
So the trick is to make an amp that hides
the onset of clipping and inevitable IMD.
Overwhelming us with stuff that we might
misinterpret as musical, rather than the
unrelated noise.
All in reasonable moderation of course.
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