Tube vs. Solid State Preamp
in [Design]
|
Prev: How do you call
Next: Internet via Cellular
From: George Jefferson on 31 Mar 2010 20:16 "Adrian Tuddenham" <adrian(a)poppyrecords.invalid.invalid> wrote in message news:1jg8ngr.1g7xp3le9s3eyN%adrian(a)poppyrecords.invalid.invalid... > �Leo� <leo2100(a)gmail.com> wrote: > > [...] >> This happens so because the transistors are more ideal amplifying >> devices than tubes are...so the signal that comes in is the one that >> comes out, with as little distortion as possible. Since the tubes are >> less ideal, they add different components to the original signal... >> this have turned out to be more pleasant to the human ear. > > I would disagree with this statement. The curvature of the transistor > characteristic is much sharper than many valves and the harmonics > generated are much nastier-sounding. Valve stages with no feedback are > quite common and the distortion they generate with moderate signal > voltages is quite tolerable, but transistor stages with no feedback are > virtually unusable for audio. > > Transistor amplifiers can contain more devices in less space for the > same price and that allows them to employ much more feedback than valve > ones, not just overall but within individual stages; this is what gives > the improvement in overall linearity which you have erroneously > attributed to the devices themselves. The down side is that when they > eventually overload, they do so much more sharply and generate higher > harmonics, which sound vile. Most amplifiers are not meant to distort. Distortion is generally a bad thing in 99% of applications excluding intentional use for audio effects. If a solid state amplifier is distorting and not suppose to then it is because the circuit was designed improperly or it is not being used properly. A tube circuit can never beat a properly designed solid state circuit for distortion free sound. For audio, this is not necessarily good as I mentioned in my original reply. A tube amp emphases the even harmonics which are octaves of the fundamental(except for one 5th and up to the 8th harmonic). The odd harmonics emphasize a dom7th chord sonority which means that if you play any chords you are effectively playing a collection of dom7th sonorities(almost anyways). This means the distortion will sound harsh no matter what you play as there will be a great amount of dissonance created. Good for metal but not for a warm sound. Again, in a properly designed solid state amplifier one will not have distortion(well, the THD will be extremely low to effectively be 0) and a tube amp will always have a higher THD(but designed properly it will still be low). The problem with tube amps is that in most basic amplifiers the load line vs the plate characteristics are non-linear over a large range which will introduce a compressive effect which creates distortion. Transistors have a similar effect but much more linear. People generally prefer tubes because when they do distort they distort "nicely". Again, the point is, in a properly designed system where distortion is meant to be minimized you cannot beat solid state. The problem is that a SS amp may do it's job too well resulting in a dry unmusical sound. The tube amp will color the sound in a good way resulting in a more musically pleasing experience. If you neglect the musical aspects of amplification SS amp's win hands down in every aspect except possibly power handling(but not so much any more). Again, it depends on the specifics but this is the general case. Tubes are generally better for musical applications in most cases. The good thing is, we can use both types to get the best of both worlds. When we require absolute accuracy in amplification we use solid state. When we want the musical effect we use tubes. We might, for example, choose to use solid state amplification for a mixing desk's inputs and it's outputs are tube based. Or simply have one final tube for the output(PA or whatever), which offers less control over the individual tracks but requires far less tubes. An analogy is incandescent and LED's. In fact, this is much more than an analogy as they both operate from the same physics.
From: krw on 31 Mar 2010 20:43 On Wed, 31 Mar 2010 14:16:47 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)On-My-Web-Site.com> wrote: >On Wed, 31 Mar 2010 22:11:17 +0100, >adrian(a)poppyrecords.invalid.invalid (Adrian Tuddenham) wrote: > >>�Leo� <leo2100(a)gmail.com> wrote: >> >>[...] >>> This happens so because the transistors are more ideal amplifying >>> devices than tubes are...so the signal that comes in is the one that >>> comes out, with as little distortion as possible. Since the tubes are >>> less ideal, they add different components to the original signal... >>> this have turned out to be more pleasant to the human ear. >> >>I would disagree with this statement. The curvature of the transistor >>characteristic is much sharper than many valves and the harmonics >>generated are much nastier-sounding. Valve stages with no feedback are >>quite common and the distortion they generate with moderate signal >>voltages is quite tolerable, but transistor stages with no feedback are >>virtually unusable for audio. >> >>Transistor amplifiers can contain more devices in less space for the >>same price and that allows them to employ much more feedback than valve >>ones, not just overall but within individual stages; this is what gives >>the improvement in overall linearity which you have erroneously >>attributed to the devices themselves. The down side is that when they >>eventually overload, they do so much more sharply and generate higher >>harmonics, which sound vile. > >Unless you build in "soft" limiting and make 'em sound toob-like :-) Ah, precision distortion.
From: Joerg on 31 Mar 2010 21:04 John Larkin wrote: > On Wed, 31 Mar 2010 13:36:54 -0800, Robert Baer > <robertbaer(a)localnet.com> wrote: > >> John Larkin wrote: >>> On Tue, 30 Mar 2010 08:56:08 -0700 (PDT), Chris >>> <christopher.maness(a)gmail.com> wrote: >>> >>>> With today's modern technology, is it possible to make a solid state >>>> preamp that is as quiet as a good tube pre? >>>> >>>> I am thinking about building a preamp. >>>> >>>> Thanks, >>>> Chris >>> Tubes are noisy. >>> >>> John >>> >> Try running a 12AU7 with a plate supply of 45V and grid-to-cathode >> voltage of about -1.5V (tweaked for zero grid current). > > What are the voltage and current noise densities? > Don't know about the 12AU7 but the 7788 or in civilian E810F could get to around 1nv/rtHz when rigged as a triode (it wants to be a pentode in normal life). I wish Sovtek, Svetlana or one of those companies would make it. In an environment where a big zap to an input is sort of normal these are really useful. Even a real zinger with a blue flash inside the glass and an audible pop typically leaves a tube unfazed. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jim Thompson on 31 Mar 2010 22:28 On Wed, 31 Mar 2010 18:04:35 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Wed, 31 Mar 2010 13:36:54 -0800, Robert Baer >> <robertbaer(a)localnet.com> wrote: >> >>> John Larkin wrote: >>>> On Tue, 30 Mar 2010 08:56:08 -0700 (PDT), Chris >>>> <christopher.maness(a)gmail.com> wrote: >>>> >>>>> With today's modern technology, is it possible to make a solid state >>>>> preamp that is as quiet as a good tube pre? >>>>> >>>>> I am thinking about building a preamp. >>>>> >>>>> Thanks, >>>>> Chris >>>> Tubes are noisy. >>>> >>>> John >>>> >>> Try running a 12AU7 with a plate supply of 45V and grid-to-cathode >>> voltage of about -1.5V (tweaked for zero grid current). >> >> What are the voltage and current noise densities? >> > >Don't know about the 12AU7 but the 7788 or in civilian E810F could get >to around 1nv/rtHz when rigged as a triode (it wants to be a pentode in >normal life). > >I wish Sovtek, Svetlana or one of those companies would make it. In an >environment where a big zap to an input is sort of normal these are >really useful. Even a real zinger with a blue flash inside the glass and > an audible pop typically leaves a tube unfazed. We've sort of shot ourselves in the foot with our desire to get everything on a single chip... I'm often puzzled why a hybrid... tubes plus transistors... wouldn't be the nicest solution. I've actually made a very HV transistor by using a tube with a grounded grid and an NPN in the cathode path. Size? Ever see a Nuvistor ?:-) And I can't remember what they were called... a stack of ceramic spacers and metal grids... really small. One jokester had the "heater" from a blowtorch ;-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy
From: Bitrex on 31 Mar 2010 22:40
Jim Thompson wrote: > On Wed, 31 Mar 2010 18:04:35 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Wed, 31 Mar 2010 13:36:54 -0800, Robert Baer >>> <robertbaer(a)localnet.com> wrote: >>> >>>> John Larkin wrote: >>>>> On Tue, 30 Mar 2010 08:56:08 -0700 (PDT), Chris >>>>> <christopher.maness(a)gmail.com> wrote: >>>>> >>>>>> With today's modern technology, is it possible to make a solid state >>>>>> preamp that is as quiet as a good tube pre? >>>>>> >>>>>> I am thinking about building a preamp. >>>>>> >>>>>> Thanks, >>>>>> Chris >>>>> Tubes are noisy. >>>>> >>>>> John >>>>> >>>> Try running a 12AU7 with a plate supply of 45V and grid-to-cathode >>>> voltage of about -1.5V (tweaked for zero grid current). >>> What are the voltage and current noise densities? >>> >> Don't know about the 12AU7 but the 7788 or in civilian E810F could get >> to around 1nv/rtHz when rigged as a triode (it wants to be a pentode in >> normal life). >> >> I wish Sovtek, Svetlana or one of those companies would make it. In an >> environment where a big zap to an input is sort of normal these are >> really useful. Even a real zinger with a blue flash inside the glass and >> an audible pop typically leaves a tube unfazed. > > We've sort of shot ourselves in the foot with our desire to get > everything on a single chip... > > I'm often puzzled why a hybrid... tubes plus transistors... wouldn't > be the nicest solution. I've actually made a very HV transistor by > using a tube with a grounded grid and an NPN in the cathode path. > > Size? Ever see a Nuvistor ?:-) > > And I can't remember what they were called... a stack of ceramic > spacers and metal grids... really small. One jokester had the > "heater" from a blowtorch ;-) > > ...Jim Thompson It's not real recent, but I wonder if you've seen this: http://www.escholarship.org/uc/item/3rd0g181?display=all |