Anyone know how to bias output tubes (using built in meter) on a Stereo Knight M-40 (Int. Amp)?


Hello
I recently bought a Stereo Knight M40 Integrated Amp, but don't know know to bias the tubes. Please reply if you know about Stereo Knight amps, and know how to get the bias meter to work.  
Thanks
Ron
larrymikeron

Showing 4 responses by freediver

Google turns up ZERO info on Stereo Knight M40 Tube Amplifier.Are there any visible Bias Pot openings on the top plate near the power tubes?Are you sure the meter is for tube biasing?It seems to me if they provided a meter biasing pots should be easy to get to.If nothing is visible your going to have to open the bottom plate & have a look around.WARNING,there are capacitors inside that will store enough voltage to stop your heart in a,well heartbeat,ONLY DO THIS UNPLUGGED & AFTER A FEW HOURS SO CAPS CAN DRAIN.If you don’t like doing this  you’re going to have to take it to an ece.tech.
Sounds like the meter acts as test point.Disregard RCA's for now.They shouldn't have anything to do with biasing.Try setting switch to #1,then slowly turn tweak(your word)next to tubes & see if meter changes.NOTE setting before moving tweak so it can go back.Pics in your link don't work.Maybe you could post pics in a virtual system so we can see it.
Ok,Google turned up just enough info.I believe the 4 RCA's are so the passive preamp section can be isolated from the amp should you choose to use a different one.I think the problem is you must have a load on the amp to Bias.The single slot adjustment screws next to each power tube & the 1-4 switch should work together.First thing I would do is hook everything up & see if you get any sound.If your getting sound & the meter doesn't register it may be broken.Once you've confirmed the amp does work try the switch & bias pots,see what happens.Beautiful amp by the way.Good luck.
I wanted to elaborate on my findings re:the 4 RCA's on the side.First I am only about 70% sure that the info I found also applies to the S40 as it comes from the S.N.stand alone Reference PreAmp,which is the foundation of the PreAmp in the S40.Apparently when used as an Integrated Amp the S40 has an Active Class A PreAmp Stage.If I'm right the 4 RCA's are in to the Passive Stage of the PreAmp & out with just enough gain to drive the reference monoblocks they offered.Once you get the amp running you can test this theory.