Audio Research I/50

Somebody asked why ARC didn't "just include" auto bias in the i50.  Because it costs.  And it would then compete with the more expensive models.  

I don't know if this is how they did t, but the old Classic 30, 60, and 120 amps used a servo...an inexpensive chip...to maintain bias once set.  That's what Raven did on their $5k integrated. 

Auto bias circuits have been done for years.  But is the "auto" when it is static, while the tubes idle?  What happens when you turn up music?  Or tubes age?  Or one tube goes a LITTLE whacky? Or maybe it was whacky when you bought the amp?  

I will admit that if it were me buying an i/50 I would prefer easier bias. But as a tube amp owner for over 20 years (all ARC other than an Ampsandsound Nautilus), bias does not normally drift very. much in a stock set of tubes. Everything changes is you swap out tubes. ARC obviously did not bring the i/50 to market for tube-rollers. 

With a push-pull pentode design, bias adjustment is vital but again, the consumer could easily get two years of use out of the amp before needing new tubes and bias adjustment. FWIW,  my SET HK Citation-based Ampsandsound Nautilus does not offer any bias adjustment whatsoever and does not need it as a matter of circuit implementation. And that is regardless of being able to swap tube types for the power tubes and rectifiers. 

I’m an AR I50 buyer and I want easy or auto bias and don’t want to mess around with tubes, changing or rolling tubes. The tube rollers and tube biasers may want to focus elsewhere.

But I really want the AR sound in something I can afford and a simple good looking integrated ......and the proof is in the listening - when I heard this amp driving Maggie 1.7i speakers the sound was clear, detailed, spacious and sounded terrific.

Balanced Audio Technology VK-3000SE (replaced by VK-3500 which is, I believe, same internals in a new box). I used Audio Research for ten years then switched to BAT and never felt I was missing anything. BAT is just pure music. 

@malibu457 , the reason there is no auto bias is because there isn't room to fit it , I saw a very interesting video on Youtube where they explain the ( few ) trade offs due to price but mainly design limitations in that chassis , which apparently wasn't originally an in house ARC design but elsewhere in the MacIntosh Group .