I hate biasing!

I have owned the Audio Research Reference 75 for close to a year now and do not foresee it leaving the system anytime soon.  BUT...I am continually challenged by lining up the biasing stick with the screw associated with biasing each side each side of the amp...If you own this amp would appreciate any shortcuts you have found which streamlines the time it takes to correctly position into the screw.

Ag insider logo xs@2xmattkimb96
Post removed 
We used to put heat-shrink on all our screwdrivers for that exact reason back in the day in the service dept. It also avoided shorting against the chassis if there were voltages present.

I own a Ref 150 SE and have to bias 8 KT-150 tubes.  Can't say I love manual biasing either.  

FWIW, I think ARC just came out with Ref 160 mono block amps that have an auto bias circuit.  No more fuss or mess.  

Interesting change of philosophy at ARC. I recall many years ago a conversation I had with either Lenard or Kal about the benefits of manual biasing.  One or both of them told me that ARC thought that an auto biasing circuit would in someway degrade the purity of the signal path.  Perhaps ARC's R&D folks figured out a way to insert an auto bias circuit that is more benign to the circuit, …  or maybe the original philosophy was just bogus. Dunno. 

Whatever the reason, I surmise that ARC's original philosophy at the time was sincere. I gotta believe that the marginal cost increase associated with adding auto biasing components was de minimis when compared to the MRSP of the amp.


Hey Liz, … is that you.  Are you back??  I've been off the Gon for some time.  If it's you, glad to see you posting again.  :)  BIF
I now own the Carver Raven 350 Tube amps. Though the adjustment is on the back and the meter is in the front. One adjustment and all tubes are set.

Post removed 

Try biasing  a pair of Canary M 350 monoblocks. Screws like on the inside of a watch and not Philips heads either. however, I wouldn't trade them for anything under 40k.

 You should be using a plastic bias adjustment tool and not a screwdriver. If you are using tubes that are properly matched, you should not have to adjust the bias much once the tubes have initially settled in.

 The ARC Ref amps are very easy to bias. There are a lot of more difficult amps to bias. Look at some of ARC's older tube amp designs.

Once I get the plastic bias tool into the podemeter adjustment screw the biasing is a snap.  Just can take awhile to get the plastic tool into the relatively small adjustment.  I am typically biasing ever 4 to 6 weeks.
4-6 weeks? Is that normal? Am I being remiss with my (non ARC) amps? I did it once 2 years ago and they’ve been fine since.

Dave Gordon is coming to Dallas for an event next week, a 160M demo. I plan to go and I’ll ask him about the impact of auto-bias on signal path.
Please let us know what he says. He is a pretty straight shooter. 
Long before ARC approved KT 150s for the Ref 150 and while they were house testing for what seemed like a year, I asked him at a show if I could drop them in without worry. He looked me in the eye and said. "Do it. Don't worry."
Of course, I did and he was right.

 I check the bias of my Ref 110 every month or so. But I have not had to adjust the bias in quite a while. They are always spot on. Usually I only have to adjust the bias the first couple times after I install new tubes. After the tubes settle in the bias should not move much. If you tubes are continually drifting, there could be an issue. How many hours are on the tubes? When tubes start getting to the end of there life span, they can start drifting. 

It makes sense to me that ARC is finally offering autobias.  I have both manual and autobias tube amplifiers and certainly do not hear any sonic degradation with the autobias amplifier.  In fact it's the best sounding amplifier I've ever had. So without question autobias can be implemented quite successfully. 
Do you have the yellow plastic tool that ARC supplies with their amps? It makes finding the slot in the trim pot so much easier than using a screw driver. Also some of ARC's amps make it easier to actually see the slot of the trim pot whereas with others it is blind. I had a VS110 and no original tool and it was a totally blind and frustrating "pin the tail on the donkey" exercise. My Ref 150SE makes it easy to see the slot and since I bought it new it came with the original tool that for some reason, again makes it easier. I suspect the shape of the blade is optimized for the slot. 
Pin the tail on the donkey is a great analogy.....I do have the yellow biasing tool....not sure how many hours are on the tubes.....in the 6-8 week intervals there is not a lot of drift but eneough that I want to use the tool to adjust. I would love the autobias aspect and if they ever offer an upgrade that brings this attribute to the Ref 75 I'd probably do it.  The Aesthetix Atlas amp does autobias but there is no dealer here and I would definately want to hear/compare it to the Ref 75 before going that way.  I have their Pandora Dac and have had the Calypso in the past and love/loved both of them.

Thanks for all of the feeback and Elizabeth its nice to see you "back in the fold".
The Asthetix Atlas has a transistor output stage so there're no output tubes to bias. The only tubes are the small signal types in the input section of this amplifier. The Atlas probably sounds different from the ARC REF 75 but not necessarily better.
I agree completely. I used to have a Marantz 8b and it drove me to distraction with all the fussy fiddling over the bias. Get an amp that has cathode bias. Likely cost you less and save all the fuss and bother.
As a prior owner of a ARC D series amp...which I actually thought was a phenomenal amp, I can definitely say that the biasing scheme was ------


My new tube amp has auto biasing, which has elevated this once serious concern to a non entity. Plus, the new amps sound even better than my old ARC.

Post removed 
The bane of my life, bar none, is biasing my beloved VAC Phi 300. I have to lower my arthritic bones onto the floor, stomach down,  to adjust the 8 tiny indented screws with the flat blade on a wooden stick. Oh yes, don't forget wearing a headlamp to discern the slot. Oh and then, there's the getting up from the floor. Oy. I think the whole operation would be better served by a hook and ladder crew.
Ya'know.....there are excellent sounding solid state amps on the market now.....
Post removed 
As I mentioned in another Ref 6 thread re plexi covers, I just traded in my Ref 5SE for a Ref 6.  While at the dealer, I saw that he had a pair of Ref160Ms tied into Magico S5 MK II speakers.  Didn't get a chance to take a listen.  

Has anyone had a chance to check out the new Ref 160?  Major bucks.  The pair lists for $30K.

I read the Ref 160 specs.  They are identical to the Ref 150SE.  Means nothing of course, but I am curious if anyone has a done a serious listen, especially if they are familiar with the Ref 150SE.  

Quite curious if the Ref 160s are in "another league" as compared to the Ref 150SE.  Given that  a Ref 160 pair costs twice as much as the Ref 150SE, I can only assume they will sound twice as good.  lol

Just yesterday I read the Stereophile review of the REF 160. See John Atkinsons measurements and comments. The cost is high at $30 K but two amps are always more expensive. Lots of power though.

At first I thought the Ref 160 monos were a Ref 150SE split in two.  Separate power supplies and power trannies of course.  But a close look at the specs show some small differences.  So maybe the Ref 160 does have some new bells and whistles that add to SQ.  

For example, I understand that the Ref 160 can be switched to play in triode mode.  Mike, a dealer and founder of Audio Shark, reports that  triode mode is like being in heaven.

Oh, a point relevant to this thread, as I mentioned above, the Ref 160 auto biases.  That's a nice feature.

All that said, there is no way I would drop $30K on an amp (or in this case, ... amps).   Aside from space issues, after my wife got done with me, I'd be talking like Minnie Mouse.


Wait for the Ref 160 SE, which will come out as soon as sales of the original drop off. It will make the non-SE original sound broken. Actually, it probably will be ;-).