Has anybody heard the new Audio Research LS 27?

Again, I have a hard time with people complaining that they use the same circuit or similar circuits year after year. As a Warranty Repair Station for ARC, I can say without question their circuits change as do the parts they use. If people need to complain about this they can build their own line stages. It is not an easy task. Some people sure know how to beat a dead horse.

I have done a bit of research on the differences between the LS26 and LS27, trying to read between the lines but I really couldn't determine anything substantially different other than a beefier power supply and different parts. It seems the chassis is a little deeper as well but the circuit is basically the same. The LS27 also weighs less. As the owner of a 10 lb amp I don't hold much weight that weight matters but power supplies and filter capcitance sure do which usually add some weight. All accounts seem to attest that the LS27 is a step above the LS26 in listening impressions.

My question to Hifigeek1 as you seem to be quite familiar with the circuit designs of ARC products in general. Is there a REAL difference in the circuits between the LS26 and LS27 or just modest changes in parts and power supply? Your comments about the 6H30 tube and an improvement over the 6922, greater transconductance I presume which surely would benefit the sonics subjectively. I can only imagine if this tube were implemented in an SP-10 with its tube regulation and quite large power supply. This is MY point and Onhwy61's as well. I don't want to come across as bashing ARC, I'm not. A healthy ARC is a good thing for the audio industry but the point is that there really doesn't seem to me to be anything revolutionary over the past 25 years in the design of their products although there is little doubt that there have been incremental improvements based on refinements more than radical new approaches, outside the box thinking, if you will. Just curious on your thoughts.

It does seem automotive technology has changed dramatically over the past 40 years, not so with linestage circuit designs. For those with money to spare, getting the lastest ARC then flipping it 3 years later for the latest ARC is fine -why not, does no harm and they are excellent linestages. But if money was an issue and you wanted to have a wonderful linestage you could easily buy a 20 year-old ARC preamp and be very much in the company of what any ARC preamp has to offer - a good sounding linestage - there simply has not been that much improvement or new knowledge of how to design a linestage - better part always helped, then and now.

I currently have a ARC line stage that I bought in 2000. I have never heard any of the newer line stages. Now I'm curious to take my line stage to an ARC dealer and compare it with the newer models.

Granted, there are not thousands of ways to amplify a signal. Circuits change when designers have the insight to use a SOTA device in a new way. In tube design it would be utilizing a new tube. The circuit topology has to change to take advantage of it. True you have less design options wih tube products then transistor. Bipolar transistors give way to j-fets at preamp inputs thereby lessening noise. Some of this is semantics. What is your definition of a circuit topology change? Are you aware of the fact that the way you lay the circuit board out, the circuit board material, and the thickness and width of the traces can make or break a potential design. It is true that if a designer finds that a particular circuit in a product like a power supply sounds particularly good, (yes power supplies do have a strong effect on an audio circuit), they might use it in another design. You have to remember that it's the whole package, not just individual parts or circuit topology that make up the sound of the unit your listening to. Some manufacturers actually remove or update parts as they become available after the first design because it sounds better or gives better reliability. That's not being cheap, that's improving performance and that would be a circuit topology change. In fact a new manufacturer of amplifiers has just come out with a new output transistor circuit that doesn't utilize emitter resistors. That to me is a new circuit design. I don't think someone like Nelson Pass or John Curl would say there had been little change in line stage design over the past 40 years. When new parts come out, circuits change. Everyone is entitled to their opinion.