Does it come with the amp?
Guest post by author Robert Wayne. This is Part 3 of Audio, the Quest for Individual Nirvana.
It is more important to find good synergistic match between your amplifier and speakers more so then any other two components. There needs to be a companionship between the two or you will never get good results and probably get very aggravated along the way. When creating a system, in particular when you’re putting things together for the first time, you must look at the big picture or you’ll be endlessly back pedaling. Like I said in the speaker article, you should have a very good idea of what you want before you start buying components, this is very true of both speakers and amplifier, you may not purchase them at the same time but you should know what your getting into, so you don’t box yourself into a corner.
Again, you have to answer some long range questions before you can safely move on. First of all you MUST know what your powering, pick speakers first, amp second; it is much harder to find a speaker you can live with then an amp you can live with. By this time you must know if you want multichannel or stereo. You also must have a broad outline of what you want for sources, cd player, dvd player, gaming system, turn table, etc… You also have to decide if you want an active pre-amp or do you want to explore other options. Before we jump into some of those specifics we’ll discuss the various types of amps, what type of speakers they work well with and what other options are out there.
There are two completely different types of amps and in then many different designs inside each type. There are tube amps, which use tubes instead of more modern semi-conductor devices in the input and output stage and Solid-State(SS) which replaces the tubes with more modern semi-conductor devices. Explaining the two and debating which is better is a never ending battle, so for sake of these articles we will keep the technicalities and opinions minimal, unless, of course, there is interest in having a more in depth discussion of tubes vs. SS. To complicate things there are many different tube and SS designs and more recently they have combined both and created what are known as hybrids, which use tubed input stage and SS output stage. There are a few generalities we will go over about each and break them into a few groups and briefly discuss the benefits and shortcomings associate with all of them.
Starting with SS, the common classes are: Class A, Class B, Class AB and Class D. Keeping things simple, class A is best described as conducting full output power at an idle and as you use them the power is sent to the speaker and using less electricity. Class A amplifiers are typically more linear and less complex then other types, but this comes at the expense of extreme inefficiency, which also equates to heat. Class B are not that common and the simple explanation of how they operate is they have at least two output devices running at half “power” which equals the same single output device running at full power, this creates less heat, and more power from less electricity. Class AB combines both, and switches as it most efficient, idling they don’t get near as warm as Class A and they will offer the first few watts in Class A with the bulk of the power being Class B. Class D is known as a switching amplifier and is more complex, but much more efficient, only recently have Class D entered the realm of Hi-Fi but as they refine them this seems to be the clear future for SS. They are smaller, lighter, more efficient, and more powerful then Class A, B or AB. As this technology develops they become significantly better, a few years ago Class D amps were laughed at, now they are becoming a major players in the amplification game. Class D are often referred to as “digital” amps and this is a misunderstanding, they are not digital, while they can use digital output signal control they can also use analog signal control. Typically the input modulation is digitally controlled, which is how this improper term has been cast on Class D. Many like Class A from a purist sense, they are simpler and thus a less corrupt path for the signal to travel, with Class B being more complex, Class AB taking it one step further with Class D being the most complex. Subsequently Class D will produce the most wattage from the least amount of electricity, followed by Class B and AB, in terms of absolute power output these two should be very similar in power consumption used to create the power, with Class A being the least efficient. Typically SS amps produce more power at lower impedance but are safe to operate in the 4 through 8 range, before you go higher or lower you should make sure the amp is stable enough to handle the load.
If your not confused yet, you will be soon! Tube amps are even more confusing, despite the older and simpler technology, it is an unknown world to most and thus very confusing at first glance. There are 3 main varieties of tube amps, Single ended triode(SET), Push-pull and output transformer less(OTL), these are general terms and there are other types that some would argue are their own category but for the sake of keeping it simple, we’ll lump everything in these categories. Tube amps differ from SS not just in sonic signature but in how they operate best, SET and OTL amps typically work better on 8 ohm and higher speakers, some are capable of powering speakers of lower impedance but these are the exception rather then the rule. Most SS amps double as the impedance is halved, tube amps will do nearly the opposite, producing more power with higher impedance, with in reason of course. Push-pull amplifiers are more flexible, in fact, many modern amps using this design are capable of powering 4 ohm speakers with aplomb, but check with the manufacturer before you assume anything. SET and OTL are the simpler and purer form of tube amps, but have limitations, in particular with SET’s they usually only produce very small amounts of power and thus require extremely efficient speakers. True OTL amplifiers work much better on higher impedance speakers, however there are hybrid OTL amplifiers that do have an output transformer, but not in the conventional sense, it buffers between the speaker and amplifier so the amp sees a safe impedance for the amp, working more passively then a conventional output transformer, some argue that these are not true OTL’s because there is a transformer in the output stage of the amp, regardless how it is implemented.
Tube amps require more hands on attention then SS, essentially all you have to do is let a SS warm up to proper operating temperature(which may literally take days) and it will perform optimally. On the other hand tube amps require more attention, and subsequently can be tuned with tube rolling. Tube Rolling is what it is called when you swap different manufactured tubes into the amp. Tubes also wear out, so it is an added expense, rare tubes can get very expensive, but can also completely change how the amp sounds. Typically tube amps will have input tubes(which are usually fairly small), output tubes(which usually are larger) and also sometimes come with driver tubes -which have little to no impact on the sound. Tubes also require what is known as biasing, some amplifiers come with what is known as auto-bias, which means they bias themselves, others require a more involved procedure. Biasing, is in simplest terms described as adjusting the voltage so it is with in the specified range of the manufacturer, this is required on every output tube. The principle is the same for all tube amps, however the procedure itself can vary greatly from manufacturer to manufacturer. So if tubes are an added expense, and requires significantly more maintenance you might be asking yourself why anyone uses them, good question. Tube amps sound very different from SS, they are more organic with a euphonic “glow” to the sound. This may sound ridiculous right now, but after you listen to several of both it will be easily discernible. And yet some audiophiles just like the hands on involvement tubes add to a system, it makes them feel more connected to the system. I’ve owned both and enjoy both immensely, but for very different reasons. There is no right or wrong answer, it depends what you want, what your powering and how involved you want to be in maintaining your system. In addition to the ease of operation of SS amplifiers, they are known for controlling the speaker and producing phenomenal bass, being low in distortion. They don’t have the organic tone tube amps do, some feel this tone is distortion and corrupts the music and others feel it brings them greater satisfaction. There is no way of knowing which you prefer with out listening for yourself. I will mention that due to the demands of home theater systems, most use SS amplifiers for the power and control, though some have successfully used tubes and swear by them.
In the last few years there have been more hybrid amps coming to the market, these bridge the gap between tubes and SS. They have a tube input stage with SS output stage, this give you the ability to roll tubes and tune the sound to your preference and the power, control and efficiency of SS. Typically, input tubes last much longer then output tubes, are cheaper and don’t require biasing. This is a much more flexible option for those who want some of the tube “magic” but don’t want to deal with the work tube amps require. The bulk of hybrid amps are integrated amps, which is an amplifier, with multiple inputs and a volume control - much like a receiver in the mid-fi world, however, these have no digital signal processing and are basically a two channel preamp and amplifier built into one. While many audiophile disregard integrated amps, they offer a tremendous value and are usually only marginally compromise sound quality compared to separates and often will save you thousands.
As you begin your quest for audio nirvana I am sure there will be specific questions about both types of amplifiers, I will try to frequent these articles to help guide you through the confusing audio maze. In the mean time be sure to check back in often as the next article comes your way, for the next article I will combine two components, sources and preamps - this should be less confusing then the speaker and amplifier articles.



