Influence of DC offset on bias

A SS amp without autobias circuitry or stabilization of quiescent current faces these following problems also previously mentioned by Kirkus:
1. due to the age the parameter mismatch percentage increases.
2. due to the temperature and other room conditions mismatch increases unlike vacume tubes.

There are quite large number of quiescent current stabilization circuits designed and created so far and they have advantage or disadvantage of one to another, but the best ones IMHO is implemented in Bryston amplifiers.

Up until before this post I believed that every SS amp post mid-70's will have it as a matter of fact and quite frankly, I'm shocked of what so-called 'purists' are able to build these days. If you somehow will be able to shoot me the circuit diagram, I'd like to take a peek on that.

As to Meridian 559, I'm surprised. It should be something else on the signal path such as loose wire(interconnect?), solder joint, preamp volume pot etc...

I have no schematics but the LSR&D amp was designed by Marshall Leach at Georgia Tech University and is the well known Leach Low TIM amp. Few were commercially produced and subsequently became a DIY project for which Dr. Leach provided parts and instructions via mail order. It's easy to find schematics for this amp just by googling. There was nothing wrong with the 559 as far as I could tell. It functioned as it should. It was just unimpressive. All of the other amps I've mentioned sound better, the Leach being the best of the lot. The Ampzillas are a close second, Bedinis third and finally the 105's but only because they begin rolling off right at 20hz. It's probably why they sound so good otherwise.

and finally the 105's but only because they begin rolling off right at 20hz.

Are you realy fenomenal or you've just measured SPL to make such conclusion?

I still don't get which amp you've been trying to adjust bias? I've looked at the schematics of Superamp and it has a quiescent current stabilization(an auto-bias), but the offset is being set by Q23 in diode connection and R27 I assume at the factory only once and than sealed.

I don't know, maybe but the 105's keep you on the edge of your seat waiting for it to happen and it never does, no sub-audible bottom end at all. I adjust bias on all my amps. I have no auto bias amps. Some don't have adjustable offset. The LSR&D Superamp monos I have definitely have bias pots. There are no other ones in the circuit. The Leach Low TIM DIY circuit has had numerous upgrades over the years so you may have found an up to date version but the factory amps were few in number produced back in the late 70's-early 80's. Unfortunately and sad to say, Dr. Leach passed away this past November. Always returned his e-mails and was available to deal personally with any question you may have.

Hi Csontos . . are you experiencing differences in timbre or level between channels on some of your amps? If so, given the age of the GAS stuff, the first thing I would be looking for is dried-out electrolytics used for coupling caps, especially at the input and in the feedback ladder.