Your opinion on the evolution of amps since 70s?

Both transistor amplifiers and tube amplifiers have seen plenty of evolution since the 50s , 60s and 70s. I have had a hands on experience with both as I ran a consumer electronics repair shop for a number of years during and after college.

With respect to conventional transformer coupled tube amps: the big thing that has changed in pentode based class AB amps is increased filter capacitance in the power supplies! I have rebuilt a number of H/K Citation IIs over the years (one of the very best vintage amps, BTW). Its weakness was its power supply and properly fixed up with new parts and boosted supplies keeps up quite nicely with its modern counterparts. Mind you, to obtain such an amp and fix it up properly will cost you as much as a new amp!

Triode power amplifiers have returned, from the grave we thought they went to during the 30s or maybe during the War. They came back because triodes sound better then pentodes, despite their inefficiencies. High end cares not a whit about that but does care a lot about getting closer to the truth of our recordings. Obviously, single-ended amps reappeared too.

Balanced line applications now exist in tube embodiments and in the home. This too is different and better.

OTLs got reliable and competetive with other amplifier technologies. OTLs were neither reliable or practical in the 70s.

Coupling capacitors, resistors and filter caps have all improved immensely. Just rebuilding a vintage amplifier with newer parts using today's superior materials (non-inductive metal films, Teflon, poloystyrenes, OFCopper, etc, etc.) reaps big rewards. Modern materials sound much better due to better specs (including greater purity).

With respect to transistor amps, they too sound better due to superior materials and better power supply bypassing techniques. High power amplifiers that are also stable are rather commonplace now rather then the exception. Heatsink technologies have improved, thermal feedback means have improved and improved semiconductor devices are commonplace that were only theoretical in the 70s.

Prices have also gone up, but if you figure what inflation has done to the US economy- lets explore that for a moment:

In 1967, a near state of the art system, maybe all Marantz tube gear with a nice set of Dayton-Wright electrostatics, Revox recorder and Empire turntable would have set you back around $3,000, which was about the price of a decent car. Nowadays you pay $20,000 for the same performance (in round numbers) and that gets you entry-level transportation. High End audio today is a good deal.

Another way to look at it: Design a nice,decent box (but not a super fancy one), install a couple of $4.00 volume controls, a couple of switches and some connectors. Now you have a stereo passive volume control. Include the cost of labor to build it, the rent to house the unit while it is being built, dealer markup, shipping and so on (don't forget to include a wage for yourself...) and see how much a simple thing like that has to cost! You are doing exceptionally well or *cheating* if you come up with a retail price of less then $500.00. And that is a passive setup with cheesy controls and no active circuitry!! High end today is a screaming deal. I would not complain about the costs unless you have already walked the talk and seen the expenses that can be involved!

I believe there is some evolution from early amps to the current models today but not nearly as much as with early digital source components. I own an older Threshold Se series amp and had an interesting conversation with an well known amp designer once. I mentioned that I had thoughts of upgrading to a new amp and he suggested that I not be in too much of a hurry to upgrade yet as my older Threshold could still hold it's own against many of the current designs today.

Thanks Atmasphere for a most lucid and informative discussion. That's the kind of response I was hoping for when I started this thread. I've always known that ss amps are better today than they have ever been but now I learn a great deal about tube amp's evolution as well. I agree with you that they are among the better values out there in spite of their relatively high cost.

I fully understand and agree with you that an amp that is properly designed and built with high-quality parts costs a great deal of money, especially for a small run. I still find that too many high-end amplifiers out there spend (waste?) an inordinate amount of money on cosmetics and testosterone effects. Sure, a fancy box helps sell the amp but I for one prefer the money optimally spent on the sound. I always open an amp and do the part counts whenever I can: many high-end amps are just overpriced, period.

To be fair, I think high-end amplifiers are distant second or even third when it comes to poor values—that’s really what we are talking about. Cables and cartridges are way up there on top of the overprice/poor value list with many speakers not far behind. And I won’t even mention the ridiculously priced accessories with dubious functions out there. When you see that companies like Magnapan, Martin-Logan, Vandersteen, and Thiel just to name a few—I apologize for not recalling all the worthy ones—have been able to make great sounding products at about the same price or less in constant dollars as they did 20 years ago, you begin to wonder about the prices of other speakers.

I am way off the main thrust of this thread: amplifier evolution since the 70s. But I feel that it is important to stress an important point: the larger the gap between the cost of high-end audio and mass-market audio—or should I say video?—the further the high-end market will shrink, and the higher the unit cost of high-end gears will rise. It’s a vicious circle. Let us make great products but let us not forget about values.

Better components, not better design. But what a difference.
In '71, I bought a pioneer 626, electrovoice speakers and dual turntable for $450. With inflation, that price would be around $1,800 today. For $1,800, you can put together a system today that will sound better than the original. There is (and has been) high end equipment sold, not for the enjoyment of music; but for establishment of "superiority". Audio is not immune to status seeking.

the cost of manufacturing consumer electronics as a percentage of wholesale(this includes hi end audio)has dropped from about 35% to less than 10% in the last 35 years. the only two places to see increases have been cardboard and transportation. that $20,000 system has a hard cost of around $2000 today. this obviously does not apply to the diy'ers who took out a second mortgage to fund a company commited to building an s.e.t. capable of....well...not much. i love music, but this industry has got to be based on value for the dollar like any other.