What To Look For When Shopping For Used Or Vintage Solid State Amplifiers
Looking to add some high-end amplifiers to your setup? Estate sales are the perfect place to shop for amplifiers. Learn what to look for when buying a used or vintage amplifier.
Amplifiers are the creme de la creme of audio components. In fact, of all the parts of an audio system that matter the most for home audio, I put amplifiers at the top of the list. Yes you need good speakers, but they don't need to be as good as you think they do to get amazing sound. And while a great source is definitely a necessity, many devices today are capable of outputing very high end sound. In fact, the sound quality of an iPhone is surprisingly good considering it has no visible speaker drivers. Of course my iPhone 8 sounds crystal clear, but it lacks that definitive experience that a room filling home audio system can provide. And when it comes to filling a room with sound you need watts of power, and to get watts of power you need a dedicated amplifier for your stereo system.
Amplifiers can be made in many different ways but there are a few popular classes of amps that are relevant to our discussion. The first class is called Class A. Class A is basically an amplifier circuit that is biased on all the time. It's a very simple and effective circuit, but because it is on all the time it generates a lot of heat. So powerful Class A amps tend to be big and heavy almost by definition because of how big the heat sinks have to be to keep them cool. Class A is probably the most desireable type of power amplifier to audio aficionados.
Another type of amp is Class A/B, this type of amplifier is biased into Class A for most of the time, but when a lot of power is needed, like when you turn up the volume really high, the amp switches into Class B, Class B is more efficient but can produce distortion because of how it works. Many top quality amps are Class A/B and it's an accepted way of getting the same max power with a lot less heat than a pure Class A amp.
The last type of amp I want to mention is the Class D amplifier. Class D technology has only recently come into its own. Class D may not have the pure sweet sound that a Class A amp has, but nothing out there will top Class D's efficiency which is theoretically capable of reaching 100%. So Class D amps can be packaged very small and give off far, far less heat than a Class A or even a Class B amplifier.
So, what can we learn from these different amplifier types? Well for starters, because of how each amplifier uses power each class of amp has a different physical design. Class A amplifiers are the least efficient and most power hungry so they give off massive amounts of heat and energy all the time that they're on, such that they can heat a room on their own. As you may know, heat is the enemy of electronics, so these amps need massive cooling, in fact some of them even have fans on the inside. The sheer size of the heat sinks causes Class A amps with high power ratings to often weigh in over 100 lbs.
Now you have a general way to tell what kind of amp you're dealing with just by the physical size and weight. Amps with large heatsinks that tend to run hot are probably Class A or Class A/B, and amps with smaller heatsinks or no heatsink are either Class B or Class D. If we're talking about vintage amplifiers you definitely want to take a second look at anything that is pure Class A or Class A/B. These amps were often tuned "by ear". Basically that means their sonic signature was adjusted to suit a certain style or listening taste, they weren't just made to fit the output of a measuring device, people actually listened to them and they tweaked the sound based on preference. This is one of the awesome things about older amplifiers, they may not be the most revealing or the most accurate, but, they're often the most fun to listen to because they were designed to make certain kinds of music more interesting.
Many high-end amplifiers of the 80's and 90's were heavy, really heavy. But even today a higher end product is going to be heavier. Class A amplifiers are still dealing with the same issues of heat that have always existed, but, even for a Class D amp a high end product will still have a relatively solid build. A solid build is just part of the tradition and expectation of high end amplifiers.
Another important thing to know is that many high end brands have since gone out of business or changed hands over the years. So it's important to be brand agnostic at first especially if you don't have a good idea of the brands to look for. Just to get you started here are a few brands in no particular order to keep an eye out for when you're perusing your next estate sale:
The odds of spotting a Mark Levinson at an Estate Sale are remote as it certainly took a unique person to spend that kind of money on a stereo system to begin with. Which is why I encourage you to be brand agnostic in your searching and try to go by build quality and amplifier type instead of being a brand snob. There are unknown brands out there, companies that never made it big back in a time when economics were different, and you may stumble across something from one of these unknown companies and not have much to go on. In that case look at the build quality, you may end up taking home something really special.
Another genre to be aware of is DIY amplifiers. There's a pretty significant number of DIY amps out there that have been built according to specifications provided online by various sources. People like Nelson Pass for example were very active in the DIY community and have created some very nice sounding DIY amplifiers. I don't recommend buying a DIY amp unless you have experience with building electronics because there are dangers associated with improperly executed electronics that you want to be aware of. But, if you do get an amp you know is DIY take it to a professional repair shop and have them look it over first to make sure it's in good functional condition and is safe to use. If all is good to go you might end up scoring an amazing sounding amp built with super high quality components for next to nothing. I have done a couple DIY projects and always choose the very best quality stuff for the things I build. Many popular projects really do sound awesome, as good or better than all but the very best mass produced products.
When referencing build quality as a standard there a few basics to be aware of. Look for items that have spade or banana style binding posts.
If an amp has a robust machined faceplate opposed to a flat piece of metal, you're almost certainly looking at a higher end item. Pretty much all cheaper amps are going to have a thin flat face plate that has screen printed lettering but of course some expensive amps will have thin flat faceplates as well. It's just a general rule that if something looks impressively built and designed the company is probably trying to hit a very high price point. Removable power cords using IEC power sockets are another item typically found on higher end amplifiers. Obviously not all will have this feature depending on the age of the item but many will.
If there is a fixed power cord most higher end and higher power amps built in the 80's or later will usually have a 16 gauge or bigger power cord. It may seem like nothing, but when it comes to delivering the perfect sound saving a few cents on the power cord isn't part of the equation.
Remember to take the information you have and apply it, but don't let it keep you from having fun with the experience of experimenting with different amps. Every company has a gem, some companies have a lot of gems, like the ones I mentioned above, but almost every company has at least one or two solid products that it made in its day. Just keep that in mind when you're trying stuff out, especially if it's cheap. Sometimes respected engineers worked for companies we wouldn't expect and designed a product or two that were a bit higher end than that company's typical fare. So it's good to have an open mind and a solid understanding of the different aspects of a quality build to help guide you.
As always good luck and have fun!
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