>>Whereas tubes "open up" and fail, a transistor can blow a >>few junctions and still keep operating. It might not work >>as well as it used to under extreme conditions, but it is >>still working.
This is TOTALLY wrong!! A transistor will never work even if A junction is blown!! In fact, many times transistors do not work even when a junction is not blown owing to materials impurities or if they are not thermally annealed correctly. This is TREMENDOUS amount of misinformation! Please do not do this dis-service to other members of this forum by plying them with wrong info! You have answered many, many other threads with very good info but this content in your post is far from the truth & you appear to be quite mis-informed.
Au contrare, a vacuum tube has a higher possiblity of working if it fails vs. a silicon transistor. It is a well-known fact that tubes "die" gracefully whereas silicon transistors are a 0/1 deal. In Engineering school we are taught this in Electronics 101.
>>As such, tubes are typically more fragile and >>either "work" or "don't work" acceptably.
This again a MYTH! Totally incorrect. Vacuum tubes are very hardy devices & can withstand very high voltages (as clearly mentioned by Albert Porter in his post). For eg. I was listening to an ASL 50W/ch mono block @ a dealer's store & this amp used an 845 tube. This is a radio broadcasting type tube & the grid is biased at 1500V! There is no transistor I know used in audio applications that gets biasesd this way. Tubes can take quite a beating & still reproduce sound thru them. They might not perform to their best ability (highs rolled off &/or wooly bass) but they will pass sound thru them. A silicon transistor would be long dead (smoked!) by this time. Only a catastrophic failure in the tube such as a disconnected terminal or blown grids/cathode/anode would cause a tube to fail completely.
We audiophiles are so nit-picky about our tubed gear that we have assumed that the vacuum tube is a fragile component. The vacuum tube pins are delicate & care needs to be taken while inserting the tube in its socket & yes, you can break it if you drop it on a hard surface & you could squish it if you apply too much pressure while inserting it but that does not make a vacuum tube fragile! These days not much is taught about tubes in Engineering school & so I think a lot of people are ignorant about it & assume it to be fragile.
Sorry to be so hard on you but I hope that you'll see my point & take it in the right spirit.
I agree with the oil caps explanation & why ss power amp gear is usually rated @ higher wattage for the same size chassis & relative cost. To expand this pt. further: miniaturization of silicon devices (better silicon process created by the fabs) has allowed us to put higher wattage BJTs & MOSFETs into smaller & smaller packages. Also, packaging of silicon devices has come a long, long way in the last 20 yrs thus these packages are very good at dissipating heat generated in the ss output stages. Thus, we can pack it in i.e. insert more & more of these high current carrying devices into reasonably sized chassis. The result is very high wattage ss power amps.
As hinted by Albert Porter, vacuum tubes are voltage output devices i.e. they are very good at providing a voltage swing but provide a very poor amount of current. Also, to get a vacuum tube to work with low impedances (such as a loudspeaker) one needs an impedance transformation i.e. an output transformer. You'll notice that the output xformer is huge. This is not only to provide an impedance xlation from but also to ensure that the current flow is un-impeded. There is a physical limitation of how large this xformer can become. Thus, output wattage of vacuum tube power amps gets limited. There is 1 practical way around this - the OTL amp. However, to get reasonable Watts out of it, one needs a large # of tubes (eg. Atma-sphere OTL amps) & they become space heaters (as a 2ndary function).
Hope that this helps some.
This is TOTALLY wrong!! A transistor will never work even if A junction is blown!! In fact, many times transistors do not work even when a junction is not blown owing to materials impurities or if they are not thermally annealed correctly. This is TREMENDOUS amount of misinformation! Please do not do this dis-service to other members of this forum by plying them with wrong info! You have answered many, many other threads with very good info but this content in your post is far from the truth & you appear to be quite mis-informed.
Au contrare, a vacuum tube has a higher possiblity of working if it fails vs. a silicon transistor. It is a well-known fact that tubes "die" gracefully whereas silicon transistors are a 0/1 deal. In Engineering school we are taught this in Electronics 101.
>>As such, tubes are typically more fragile and >>either "work" or "don't work" acceptably.
This again a MYTH! Totally incorrect. Vacuum tubes are very hardy devices & can withstand very high voltages (as clearly mentioned by Albert Porter in his post). For eg. I was listening to an ASL 50W/ch mono block @ a dealer's store & this amp used an 845 tube. This is a radio broadcasting type tube & the grid is biased at 1500V! There is no transistor I know used in audio applications that gets biasesd this way. Tubes can take quite a beating & still reproduce sound thru them. They might not perform to their best ability (highs rolled off &/or wooly bass) but they will pass sound thru them. A silicon transistor would be long dead (smoked!) by this time. Only a catastrophic failure in the tube such as a disconnected terminal or blown grids/cathode/anode would cause a tube to fail completely.
We audiophiles are so nit-picky about our tubed gear that we have assumed that the vacuum tube is a fragile component. The vacuum tube pins are delicate & care needs to be taken while inserting the tube in its socket & yes, you can break it if you drop it on a hard surface & you could squish it if you apply too much pressure while inserting it but that does not make a vacuum tube fragile! These days not much is taught about tubes in Engineering school & so I think a lot of people are ignorant about it & assume it to be fragile.
Sorry to be so hard on you but I hope that you'll see my point & take it in the right spirit.
I agree with the oil caps explanation & why ss power amp gear is usually rated @ higher wattage for the same size chassis & relative cost. To expand this pt. further: miniaturization of silicon devices (better silicon process created by the fabs) has allowed us to put higher wattage BJTs & MOSFETs into smaller & smaller packages. Also, packaging of silicon devices has come a long, long way in the last 20 yrs thus these packages are very good at dissipating heat generated in the ss output stages. Thus, we can pack it in i.e. insert more & more of these high current carrying devices into reasonably sized chassis. The result is very high wattage ss power amps.
As hinted by Albert Porter, vacuum tubes are voltage output devices i.e. they are very good at providing a voltage swing but provide a very poor amount of current. Also, to get a vacuum tube to work with low impedances (such as a loudspeaker) one needs an impedance transformation i.e. an output transformer. You'll notice that the output xformer is huge. This is not only to provide an impedance xlation from but also to ensure that the current flow is un-impeded. There is a physical limitation of how large this xformer can become. Thus, output wattage of vacuum tube power amps gets limited. There is 1 practical way around this - the OTL amp. However, to get reasonable Watts out of it, one needs a large # of tubes (eg. Atma-sphere OTL amps) & they become space heaters (as a 2ndary function).
Hope that this helps some.