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Mini-MosFet Audio Amplifier - RED - Page123
It struck me some time ago that an amplifier like this would work. I have some 2SD756 NPN of gain 400 that can be used up to 120V. If the BUZ900/950 was used and circuit values changed it might be even better. The gain is just over 12 which would mean 100 watts for 2.4 Vrms input which is ideal op amp output. The input resistor could be changed for 3K9 and the upper arm 47K to make it even easier to drive. Distortion should be about 0.1 % at 25 watts and well below 1% 100 watts. If you set up a long tail pair with 3K9 on the - ve side you might assume it will sound like this. I never found that. The long tail pair sets a sound for the pair. That being true it seems beter to use the + ve side. The emitter input single seems no better really. People say if a single input transistor the VAS needs no conpenstion. Not true. The long tail pair is not screwing it up as badly as that. Some will say differently.
I built an amp recently with two fets and a transfomer to be a variac. It has about 1% THD. It seems likely this amp might maintain 0.1% up to 70 watts. As most of us only critically listen up to 5 watts it could sound very good. I now have proof of this. The Magneplanars allow the Quad 303 to work right up to the current limiters. There is no real distortion, by a factor of ten less than what most people get is my guess? Spendor BC1 that has very low distortion up to 90 dB. BC1 is obviously distorted when the Quad is at half volume. These were BBC monitors so likely to be state of the art on distortion for a box + moving coil design. My baffle speakers also distort at slightly above BC1 levels. The sound you hear would be thought by most to be the amplifer, I have to tell myself it isn't as I now know better. Thus if an amp can control it's crossover distorrtion and have a reasonable output impedance ( < 0.5R ) it should sound OK. This amp as long as it doesn't have high distortion > 10 kHz should give a Dynaco ST70 a run for it's money. The feedback is the HC Lin style. The PSU could be a CCS driving the VAS and FET source follower to the dumpers ( CCS sets reference voltage if wanting it simple ). The idea is super clean and super fast. It would loose a small amount of power and ensure the VAS clips first. I suspect it is a bit optimistic to run IRF530/9530 with simple bias. BUZ900/905 would be better.
Recently I said that many speakers have a choke in series with the drive unit . No one seemed interested. When people insist a high damping factor is required and swear they can hear it I have my doubts. I suspect what really happens is that the designer has installed a good power supply to go with the mindset. I recently built a conventional PSU for a Hypex amp. On paper it should have worked. It sounded like the amp had " poor damping factor ". The PSU transformer was upgraded and caps remained at 22 000 uF as space ran out. It sounded much tighter and more focused. To be honest is sounded very poor before the upgraded PSU. Please note caps unchanged. They were United Chemi-Con as they were the smallest, cheapest and best specs by far. They state a surge voltage of 63/50V which is useful. My feeling is most people get this very wrong. It is the transformer that matters most. I had this one custom wound. Caps can be modest if the ripple current is OK. Also look at life. It can be as little as 2000 Hrs at 105 C and as much as 200 000 Hrs 55C ( Philips of old , BC, Now Vishay ). Most computer PSU's have 18 continuous months as far as certificates are concerned.
What should be said is this amp is as complex as is required to get something working. If it was fed by an op amp which has loop feedback from the output it might work very well. My guess is the one shown here migh sound more open as it's time delay is minimal. The VAS could be made a complimentary feedback pair ( MPSA42/92 ). The advantage with that is realising optimum gain. A cascode of BC109C and MPSA42 could work. There are very simple amps that throw power away. This is not one. You can use an LM317 to do that. It isn't a simple amp as it is a LM741 with output device more or less.
Dan. The problem Airpax had with that motor defeated everyone. All the " it can't fail " stuff did fail. WD 40 is nasty stuff. I think it needs nasty. I think WD40 is Napthalene ?
You know, Nige, the really funny thing is that many of those ancient designs which are capacitor coupled somehow, despite everythng, still manage to sound really good, even if theory says they perhaps shouldn't.
I remember a slew of German made audio gear from the early 70ies, based on 2N3055 in a quasi complementary and even fully complementary (with 2N2955 or BD 18) magaed to sound better than a lot of direct coupled japanese amps, even if nominally at half power of the Japs. BUT, they were built for 4 Ohms loads, as required by DIN 45500 standards, and many could actually drive two pairs of 4 Ohm speakers in parallel, so obviously, current was not a problem.
I think current capability was where most vintage amps stumbled, even some very well known and none too cheap designs from people like SAE (chief engineer was James Bongiorno). SAE amps did and still do sound very clean and clear, a delight to listen to, but they definitely don't like speakers below 8 Ohms.
I mention this because of yur beloved NAD 3020, and all it did was to more or less mimic German designs as a standalone integrated amp (Germans had few of those, they were heavily into receivers). I am not saying it was a blatant copy, but the design logic was nicked from the Germans. And I can point you to a number of service manuals for German products of the day, from people like Wega, Elac, Saba, etc.
This is where studying some history heavily pays off in spades, you what to reference one with what.
I remember a slew of German made audio gear from the early 70ies, based on 2N3055 in a quasi complementary and even fully complementary (with 2N2955 or BD 18) magaed to sound better than a lot of direct coupled japanese amps, even if nominally at half power of the Japs. BUT, they were built for 4 Ohms loads, as required by DIN 45500 standards, and many could actually drive two pairs of 4 Ohm speakers in parallel, so obviously, current was not a problem.
I think current capability was where most vintage amps stumbled, even some very well known and none too cheap designs from people like SAE (chief engineer was James Bongiorno). SAE amps did and still do sound very clean and clear, a delight to listen to, but they definitely don't like speakers below 8 Ohms.
I mention this because of yur beloved NAD 3020, and all it did was to more or less mimic German designs as a standalone integrated amp (Germans had few of those, they were heavily into receivers). I am not saying it was a blatant copy, but the design logic was nicked from the Germans. And I can point you to a number of service manuals for German products of the day, from people like Wega, Elac, Saba, etc.
This is where studying some history heavily pays off in spades, you what to reference one with what.
The thing to see here is like two stroke engines or rockets simple can work. A nice V16 will take you to the Moon ?
My point is the MOS FET is the slighly more modern design ( patents apart ). The old germanium designs were to save money. At the time the germanium amp was cheaper mainly as there was no output transformer. Piece by piece the transistors were more expensive than valves and lets be honest awful. Like CD some can never forget how transistor amps sounded then and still use valves for that reason alone today.
What we get in a MOS FET is almost an output triple. In a H C Lin style amp we now can have prefectly good hi fi. The reason we assume we can't is based on 1962 designs. Some of those amps would not do 30 kHz or even 7 kHz in truth.
Two stoke engines were the fastest in the world until polution became important. The Diesel versions are very special. Ford did have with an Australian company an advanced two stroke planned. I guess it was made impossible by regulations? If you have never tried a big two stroke you might be very surprised. No engine braking is the only demerit. With hybrids that would not be noticed. The Scott engine still has a few things about it that have never been beaten. The design is 1920's. One design needs no oil in the fuel ( Hopwood ). I proposed a Diesel lubricated and cooled version to them. His father designed the Norton Commando as did Clint Eastwood use. Diesel is good as it can be Jet fuel. Jet fuel is cheaper than AV Gas. The enigines are used for drones. They have a wonderful V4.
A quote.
The efficiency of two-stroke engines is close to 50%, while four-stroke automotive diesels struggle to achieve 35%, Renault said. The efficiency gains of the two-stroke cycle offer other benefits: compactness and a reduction in weight, given that it involves halving the engine size and number of cylinders (here a twin-cylinder). The engine is 40 kg lighter and more compact, thereby making it ideally suited to small vehicle platforms.
My point is the MOS FET is the slighly more modern design ( patents apart ). The old germanium designs were to save money. At the time the germanium amp was cheaper mainly as there was no output transformer. Piece by piece the transistors were more expensive than valves and lets be honest awful. Like CD some can never forget how transistor amps sounded then and still use valves for that reason alone today.
What we get in a MOS FET is almost an output triple. In a H C Lin style amp we now can have prefectly good hi fi. The reason we assume we can't is based on 1962 designs. Some of those amps would not do 30 kHz or even 7 kHz in truth.
Two stoke engines were the fastest in the world until polution became important. The Diesel versions are very special. Ford did have with an Australian company an advanced two stroke planned. I guess it was made impossible by regulations? If you have never tried a big two stroke you might be very surprised. No engine braking is the only demerit. With hybrids that would not be noticed. The Scott engine still has a few things about it that have never been beaten. The design is 1920's. One design needs no oil in the fuel ( Hopwood ). I proposed a Diesel lubricated and cooled version to them. His father designed the Norton Commando as did Clint Eastwood use. Diesel is good as it can be Jet fuel. Jet fuel is cheaper than AV Gas. The enigines are used for drones. They have a wonderful V4.
A quote.
The efficiency of two-stroke engines is close to 50%, while four-stroke automotive diesels struggle to achieve 35%, Renault said. The efficiency gains of the two-stroke cycle offer other benefits: compactness and a reduction in weight, given that it involves halving the engine size and number of cylinders (here a twin-cylinder). The engine is 40 kg lighter and more compact, thereby making it ideally suited to small vehicle platforms.
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Earth to Nigel, please come down out of the orbit.
While two stroke does have its benefits, they are far outweighted by its faults, primarily that of the output emissions. Please note that cars using two stroke engines, such as ex East German Wartburg and Trabant, are now banned in most of Europe (but fortunately, not in Serbia, otherwise my best man would have to sell his Wartburg and buy something four stroke). Filterig them has also been researched, but in the end, making them compliant with Euro 6 norms would cost almost as musch as the engine and would completely negate other benefits from them.
Nige, the future belongs to small capacity (1-1.4 litre) four stroke petrol engine equipped with a turbo charger. That future is TODAY, it's already here. Everybody who's anybody in European vehicle manufacturing has at least one (VW, Škoda, Audi, SEAT, Fiat, Lancia, Alfa Romeo, Ford, Renault). These engines are cery effcient, their power outputs ranging from 120 to 185 bhp (86-132 bhp/litre), which is far more efficient than any other type of engine, is small and relatively ight. For smaller and lighter yet, Fiat has a twin cylinder version of the same, and Ford has a 1 litre trhee cylinder version. Renault settled for reduced capacity version, down to 1.2 litres and 115 bhp. The efficiency No.1 spot is, at the moment, held by Mercedes Benz, who in the Class A AMG model use both all wheel drive, and a 2 litre turbo engine, delivering 360 bhp. Race versions of 2 litre engines get as high as 720 bhp (Subaru Imprezza). Remember the early 70ies BMW showcase engine with 1.490 ccm, delivering 1.507 bhp, i.e.more that i bhp/1 ccm.?
And then there are the hybrids, just a stepping stone towards fully eletric cars.
Twin stroke is beating a dead horse, Nige. New trubo assited engines easily meet Euro 6 and the coming Euro 7 emission norms.
While two stroke does have its benefits, they are far outweighted by its faults, primarily that of the output emissions. Please note that cars using two stroke engines, such as ex East German Wartburg and Trabant, are now banned in most of Europe (but fortunately, not in Serbia, otherwise my best man would have to sell his Wartburg and buy something four stroke). Filterig them has also been researched, but in the end, making them compliant with Euro 6 norms would cost almost as musch as the engine and would completely negate other benefits from them.
Nige, the future belongs to small capacity (1-1.4 litre) four stroke petrol engine equipped with a turbo charger. That future is TODAY, it's already here. Everybody who's anybody in European vehicle manufacturing has at least one (VW, Škoda, Audi, SEAT, Fiat, Lancia, Alfa Romeo, Ford, Renault). These engines are cery effcient, their power outputs ranging from 120 to 185 bhp (86-132 bhp/litre), which is far more efficient than any other type of engine, is small and relatively ight. For smaller and lighter yet, Fiat has a twin cylinder version of the same, and Ford has a 1 litre trhee cylinder version. Renault settled for reduced capacity version, down to 1.2 litres and 115 bhp. The efficiency No.1 spot is, at the moment, held by Mercedes Benz, who in the Class A AMG model use both all wheel drive, and a 2 litre turbo engine, delivering 360 bhp. Race versions of 2 litre engines get as high as 720 bhp (Subaru Imprezza). Remember the early 70ies BMW showcase engine with 1.490 ccm, delivering 1.507 bhp, i.e.more that i bhp/1 ccm.?
And then there are the hybrids, just a stepping stone towards fully eletric cars.
Twin stroke is beating a dead horse, Nige. New trubo assited engines easily meet Euro 6 and the coming Euro 7 emission norms.
Earth to Nigel, please come down out of the orbit.
While two stroke does have its benefits, they are far outweighted by its faults, primarily that of the output emissions. Please note that cars using two stroke engines, such as ex East German Wartburg and Trabant, are now banned in most of Europe (but fortunately, not in Serbia, otherwise my best man would have to sell his Wartburg and buy something four stroke). Filterig them has also been researched, but in the end, making them compliant with Euro 6 norms would cost almost as musch as the engine and would completely negate other benefits from them.
Nige, the future belongs to small capacity (1-1.4 litre) four stroke petrol engine equipped with a turbo charger. That future is TODAY, it's already here. Everybody who's anybody in European vehicle manufacturing has at least one (VW, Škoda, Audi, SEAT, Fiat, Lancia, Alfa Romeo, Ford, Renault). These engines are cery effcient, their power outputs ranging from 120 to 185 bhp (86-132 bhp/litre), which is far more efficient than any other type of engine, is small and relatively ight. For smaller and lighter yet, Fiat has a twin cylinder version of the same, and Ford has a 1 litre trhee cylinder version. Renault settled for reduced capacity version, down to 1.2 litres and 115 bhp. The efficiency No.1 spot is, at the moment, held by Mercedes Benz, who in the Class A AMG model use both all wheel drive, and a 2 litre turbo engine, delivering 360 bhp. Race versions of 2 litre engines get as high as 720 bhp (Subaru Imprezza). Remember the early 70ies BMW showcase engine with 1.490 ccm, delivering 1.507 bhp, i.e.more that i bhp/1 ccm.?
And then there are the hybrids, just a stepping stone towards fully eletric cars.
Twin stroke is beating a dead horse, Nige. New trubo assited engines easily meet Euro 6 and the coming Euro 7 emission norms.
While two stroke does have its benefits, they are far outweighted by its faults, primarily that of the output emissions. Please note that cars using two stroke engines, such as ex East German Wartburg and Trabant, are now banned in most of Europe (but fortunately, not in Serbia, otherwise my best man would have to sell his Wartburg and buy something four stroke). Filterig them has also been researched, but in the end, making them compliant with Euro 6 norms would cost almost as musch as the engine and would completely negate other benefits from them.
Nige, the future belongs to small capacity (1-1.4 litre) four stroke petrol engine equipped with a turbo charger. That future is TODAY, it's already here. Everybody who's anybody in European vehicle manufacturing has at least one (VW, Škoda, Audi, SEAT, Fiat, Lancia, Alfa Romeo, Ford, Renault). These engines are cery effcient, their power outputs ranging from 120 to 185 bhp (86-132 bhp/litre), which is far more efficient than any other type of engine, is small and relatively ight. For smaller and lighter yet, Fiat has a twin cylinder version of the same, and Ford has a 1 litre trhee cylinder version. Renault settled for reduced capacity version, down to 1.2 litres and 115 bhp. The efficiency No.1 spot is, at the moment, held by Mercedes Benz, who in the Class A AMG model use both all wheel drive, and a 2 litre turbo engine, delivering 360 bhp. Race versions of 2 litre engines get as high as 720 bhp (Subaru Imprezza). Remember the early 70ies BMW showcase engine with 1.490 ccm, delivering 1.507 bhp, i.e.more that i bhp/1 ccm.?
And then there are the hybrids, just a stepping stone towards fully eletric cars.
Twin stroke is beating a dead horse, Nige. New trubo assited engines easily meet Euro 6 and the coming Euro 7 emission norms.
supercharged 2 stroke cathedral diesels still have a future, but too complex for small capacities. F1 is showing the way of how fuel efficient you can get with forced induction.
For me the ultimate 2-stroke was the Rolls-Royce Crecy Rolls-Royce Crecy - Wikipedia, the free encyclopedia Riccardo has a section about this in one of his books.
I have a VAG 1.9Tdi at the moment. It will probably be my last diesel...
For me the ultimate 2-stroke was the Rolls-Royce Crecy Rolls-Royce Crecy - Wikipedia, the free encyclopedia Riccardo has a section about this in one of his books.
I have a VAG 1.9Tdi at the moment. It will probably be my last diesel...
Rockets are rarely simple.
[QUOTE]
The efficiency of two-stroke engines is close to 50%, while four-stroke automotive diesels struggle to achieve 35%, Renault said. The efficiency gains of the two-stroke cycle offer other benefits: compactness and a reduction in weight, given that it involves halving the engine size and number of cylinders (here a twin-cylinder). The engine is 40 kg lighter and more compact, thereby making it ideally suited to small vehicle platforms.[/QUOTE]
Can't be arsed to check my references but Brake specific fuel consumption - Wikipedia, the free encyclopedia sshows >40% efficiency from auto diesels 20 years ago.
Wow! What excellent advice - thanks! I wish I had known this 40 years ago.
I have agood friend who works for Bosch in Duessledorf in research of new fuel injection systems and applications of current systems. He heads a small team which does the implementation of diesle engines to modern passenger cars.
I asked him how did BMW manage to surpass the 100 bhp/litre point with Diesel engines, and he told me they use 4 (!!!) turbos to get there. He also said that if you have an accident with cars using those, you might as well as throw it away because it's so densly packed inside that anything more than a light bump will surely do a turbo or two in, and a new one costs typically like €1.200 each, which is about €1.600 in the service bill to install it.
So, Nige, 40% efficiency for a Diesel was in the stone age, most of them today deliver upwards from 65 bhp/litre. However, they are more expensive to manufacture than petrol engines, have very complicated common rail injetion systems which require more servicing more often. So, in fact, they cost more to buy and more to regualrly service, but thes do use less fuel, so whether one is worth your while will tremendously depend on your mileage, if you do like 20.000 per annum, they are cheaper, if not, then they are in fact more expensive.
I typically do like 6.000 kiles per annum, so the Diesel option on my car would have been the economic equivalent to shooring myself in my foot. Purchase cost 20% above the petrol version,. annual service 50% more expensive for the diesel engine.
Unfortunately, when I wanted to buy a new car, the top petrol version was a 1.8 litrge, 141 bhp naturally aspirated engine, what I really wanted was the 1.4 turbo petrol enhine with 140 bhp but mote torque and less consumption. That became available about a year later. Bummer.
I asked him how did BMW manage to surpass the 100 bhp/litre point with Diesel engines, and he told me they use 4 (!!!) turbos to get there. He also said that if you have an accident with cars using those, you might as well as throw it away because it's so densly packed inside that anything more than a light bump will surely do a turbo or two in, and a new one costs typically like €1.200 each, which is about €1.600 in the service bill to install it.
So, Nige, 40% efficiency for a Diesel was in the stone age, most of them today deliver upwards from 65 bhp/litre. However, they are more expensive to manufacture than petrol engines, have very complicated common rail injetion systems which require more servicing more often. So, in fact, they cost more to buy and more to regualrly service, but thes do use less fuel, so whether one is worth your while will tremendously depend on your mileage, if you do like 20.000 per annum, they are cheaper, if not, then they are in fact more expensive.
I typically do like 6.000 kiles per annum, so the Diesel option on my car would have been the economic equivalent to shooring myself in my foot. Purchase cost 20% above the petrol version,. annual service 50% more expensive for the diesel engine.
Unfortunately, when I wanted to buy a new car, the top petrol version was a 1.8 litrge, 141 bhp naturally aspirated engine, what I really wanted was the 1.4 turbo petrol enhine with 140 bhp but mote torque and less consumption. That became available about a year later. Bummer.
Not really, Russ. Well meant and competent definitely, but the REAL advice would be sell it off and buy a direct drive of known quality, like for example, Dual 704 or 721. Hall effect quartz locked drive motor, arm resonance right out of the text book, just +3 dB at 8...9 Hz, etc. Can be had for a VERY comfortable price as second hand.
25 years after its appearance, Linn Sondek had had its day, the others had caught up and surpassed it for less money and more tehnology. Or, if you're a THorens nutter, perhaps a Thorens 540 DD, but that's a very elusive model, very hard to find and bacuse it's a rarity, stil very expensive. German broadcasters bought off the whole lot.
I meant the value of Dexron II vs WD40, not the specific advice re the turntables. I should have trimmed the quote.
Speaking of Thorens, though, my advice to any newcomers is to avoid the TD 160. I have never heard the negative contribution an arm can make to the sound more clearly - albeit after hearing the same cartridge on a Mitchell unipivot
That I can believe, Russ.
My olde Dual CS604 DD is the first generation of Duals to have an ultra low mass arm, I think it was designed in conjunction with Ortofon. I have never heard Ortofon LM20 play so well wtih anthing else as with my Dual, and I have never heard my Dual do as well with anything other than Ortofon's LM 20. In those days, manufacturers actually talked with each other. This was a match made in Heaven.
I also have an Ortofon FF15 Mk.3 and it's no comparison with the LM20. Same company, however also lower price, but no compairson.
As for Thorens, they used to offer two arms, the TP13 and TP16. I share your sentiments regarding TP13, in my view a failure from the start, but the TP16, while more expensive, was more of an arm as well. Ultimately, it was also offered withan SME 3009 tonearm, and with it, it does work VERY well indeed. You did have your pick of the crop.
My olde Dual CS604 DD is the first generation of Duals to have an ultra low mass arm, I think it was designed in conjunction with Ortofon. I have never heard Ortofon LM20 play so well wtih anthing else as with my Dual, and I have never heard my Dual do as well with anything other than Ortofon's LM 20. In those days, manufacturers actually talked with each other. This was a match made in Heaven.
I also have an Ortofon FF15 Mk.3 and it's no comparison with the LM20. Same company, however also lower price, but no compairson.
As for Thorens, they used to offer two arms, the TP13 and TP16. I share your sentiments regarding TP13, in my view a failure from the start, but the TP16, while more expensive, was more of an arm as well. Ultimately, it was also offered withan SME 3009 tonearm, and with it, it does work VERY well indeed. You did have your pick of the crop.
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I understand that this was a general example only, but I would like to add that this can be much improved on. For example, what is shown as a CCS and left undefined, using appropriate BJTs would allow for considerably better PSU rejection. Adding a buffer transistor before the VAS trannie would very significantly reduce distorion and improve dynamic stability.
If I did it, I'd use a buffer transistor followed by a cascode for the VAS, to give it as much linearity as possible.
If I did it, I'd use a buffer transistor followed by a cascode for the VAS, to give it as much linearity as possible.
You are slightly confusing BHP/litre with efficiency (Brake specific fuel consumption). They are related of course, but it can be confusing, like telling people that a turbo petrol is more efficient than NA when any fool know an impreza only gets about 17mpg!
My Passat is the last pre-common rail units. It's rattly when cold, a little sooty when giving it beans and rarely gets over 42mpg. But its done 260k miles and engine, gearbox and clutch are original. When I finally kill it I will go petrol again. Common rail has too much to go wrong these days and new engines with tanks of p*ss to keep emissions down is not for me. I think I'll go back to LPG
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