Audio Research I/50

There is an advantage to having trim pots in certain places. When you have a product like AR, you don't want anything to look out of place, collect dust that is difficult to clean and certainly not around trim pots. Mr. Clean Jeans with his Q-Tips and micro cloth could move things. As a bulletproof design. I'd hide it too. LOL

OLD design almost always hid trim pot under the bottom plate (if there was a plate) or through a hole in the top that was covered with a metal or wood cover.

Auto bias sucks. I use it but I install trim pots on Macs. I BIAS cool. Unless I'm doing a lot of late night low volume listening. I still bias and listen. If I can keep the SQ and bias cooler I do. Why? pretty simple, the cooler you bias the longer the valves last.

BUT that is just part of the story. It also stops the power valves from breaking up sooner than they would have with the higher bias. Distortion! HF distortion, and LF both suffer when you start to crank it. The higher you go the worse it get, then you run out of gas. 

If you scope bias the actual watts created can double. Cary Six Pacs are a good example. Factory bias is 220-240ma per 6 valves. 50 wpc. Scope and alignment increased power on demand output to 100+ wpc and COOLED the bias to 160ma for 6 (lets say) EL34s.

So what do I get out of the deal being able to bias my own units?

1. A lot longer valve life, you can see why. Lower bias, lower volume, longer life.

2. Less distortion. Cleaner sound, COOLER running. 

3. More horsepower, the amps will play louder and cleaner before distortion sets in or the tubes break up.

Side note: 

I had WE 300 (116a) amps they were my fathers. That is what he left me. His snap-on tools, and Western Electric Amps. 

I learned how to maintain those valve amps. The 300WE valves that were in it were used. I had 4 new, and one used sets of valves. In 15 year of playing those watt sucking pigs close to every day, 2 sets of valves still had over 50% valve life. I know I put 30,000 hours on those amps easy. My father over 30,000 hours. He had them 20 years. He used the same set of valves all that time. 2 set were never used and I never did wear out the set my father used.

How long do valves last?

I have original Mcintosh valves in a 1968 MC225 less one 12AX7.

BTW you still have to bias most SS ampt too, you know.. :-)

Regards

The i50 is a really nice looking unit, and it's nice to see AR release a product available to those with somewhat more modest means. It is a little strange that they release a product for what could be described as entry-level (per cost...not in the quality sense) with manual bias setting, but requiring it be done by a technician. 

The skeptic in me wonders if this is a way for AR to have consumers build relationships with dealers by design (with the benefit of recurring revenue), a'la John Deere or any modern automobile.

i hope that sometime soon there will be a comprehensive review, in a serious magazine/site   about it's sound quality 

I just ordered one for a second system and look forward to providing more clarity on the biasing issue from my AR dealer.

I agree that brands like Linear Tube Audio that provide complete audio bias around this price point would generally be more agreeable to the younger listeners their branding cultivates. Even my truly high-end SA Lab integrated auto-biases its 6550 tubes, and that is meant for experienced listeners. This said, I always liked manually biasing my Octave Audio (great bias readout) and Rogue (less so) tube amps, which should be telling of how others will experience this, as I am under 40 and lack comprehensive experience with the servicing of mechanical gear relative to other fields (i.e., automobile / home repair).

In addition to assessing ease of use and seeing if I can access a service manual, I will report on how the I/50 performs in my second system, using Graham Chartwell LS6 speakers that seem to strike an appropriate price and specification balance with this unit.

@ Transience 

That's great. Let us know how you like the I/50. The Graham LS6 speakers are very nice. My assumption is that the two should be a good match. I agree with you on the Octave amps. They have implemented a unique and easy way for all users to bias the tubes.