Home Amp/Preamp Asylum

Looking for a new Amp or Preamp? If you're after tubes, post over here.

Installed fresh KT120 tubes this morning. Rebiased all to 60mV - pics

The Rogue Cronus Magnum is a lot easier to bias but the ARC isn't difficult.

Rogue Cronus Magnum : Everything is accessible from the top of the amp including it's built-in bias meter. You simply remove a small cover plate by loosening it's two captive thumb screws which reveals 4 toggle switches and 4 10-turn trimpots. Flip the appropriate toggle switch, adjust the trimpot with the provided industry standard tweaker tool, and observe the meter. Repeat for the remaining tubes. Since the trimpots are 10-turn, it's super easy to dial-in the exact bias setting without overshooting or undershooting. Once dialed-in the bias remains rock solid.

Audio Research VSi-60 : There are 4 pairs of small test point sockets on the back of the amp that will snugly fit the test probe tips from a digital multimeter. The 4 bias adjustment trimpots are single-turn and located under a hole in the chassis top plate near each KT120 power tube.

Fortunately, ARC provides a skinny plastic screwdriver tweaker tool as the industry defacto standard tweaker will not fit. The hole is too deep and the skinny part of the defacto standard tool is not long enough. OK, I'm not positive that these are THE industry standard tweaker tool but I've been using them for over fourty years since I was an electronic hobbyist as a kid.

With the bias test points located behind the ARC amp and using typical DMM test probes. I had to pull the amp forward on it's stand in order have enough to be able to see the test sockets and to clear enough space behind the amp for the probes. Adjustment was simple and stable. Just dial-in 60mV on the DMM for each tube and it remains rock solid.

Rogue with bias access cover plate removed, tweaker tool, and built-in meter. ARC bias access holes near each KT120.


ARC bias test jacks behind amp required amp to be pulled forward on stand with front of amp hanging off the front a few inches.


Dial-in ARC bias using a digital multimeter and tweak it to 60mV.


Standard tweaker tool as provided by Rogue on Left. Skinny plastic screwdriver provided by ARC on Right.





This post is made possible by the generous support of people like you and our sponsors:
  VH Audio  


Follow Ups Full Thread
Follow Ups

FAQ

Post a Message!

Forgot Password?
Moniker (Username):
Password (Optional):
  Remember my Moniker & Password  (What's this?)    Eat Me
E-Mail (Optional):
Subject:
Message:   (Posts are subject to Content Rules)
Optional Link URL:
Optional Link Title:
Optional Image URL:
Upload Image:
E-mail Replies:  Automagically notify you when someone responds.