I've Just Learned What Amplfier Bias Is...

Horrible thread.  Bias is simply voltage, e.g. a difference in electric potential, required to make a circuit or component function.  A transistor requires a bias voltage to function properly.  But so does a diode.  And that is specified according to the manufacturer, freely available on datasheets.  It's not something to tweak.  Vacuum tube bias / biasing for guitar amps is frequently required when changing tubes and some players may prefer to tweak the bias to make the tubes run 'hot'.  This can however shorten the life of the tubes and in extreme cases melt any PCB is it near.  Guitar tube amp biasing tweaks are NOT for audiophile situations.  Guitar tube amps are designed to be pushed quickly into breakup and harmonics and feedback, audio tube amplifiers are not.  I just changed tubes and biased my guitar amp.  The EL84s were 81mv average but I changed brands and the new tubes read around 60mv which is more in spec. so I didn't adjust anything.  When any tubes are changed, the bias may need adjusting, but its not something you tweak to a room.  And bias can drift.  So, for any tube amp, guitar or "audio", biasing may need periodic adjusting within a specified range...but an "audio" amp shouldn't be "biased" to produce a particular sound.  That IS what tone controls are for, if you need those or want them in the signal path.  Biasing can be done in a closet.  Biasing an amp in a particular "setting" to tune the amp is just garbage if someone is claiming that.  A "room" does not determine circuit design and unless you seek distortion, leave dials on the circuit boards where they are.

This particular post goes out to all the Agoners on here who may be somewhat new and just trying to learn about audio as myself.

Also and especially to the Agoners here who think they can post and talk to anyone here as they please while hiding behind their monikers and the internet and acting like teenage freshmen girls with an extreme bully complex. Would they do that in person? Of course not. That takes courage and as we know most bullies are cowards.

I am Tyray. That is exactly who I am. Not hiding behind anything.

The sad part is most of these Agon bullies here are grown - ass - middle aged men!

So if anyone posted something negative to my thread here....Please read this thread...again!

https://forum.audiogon.com/discussions/axe-to-grind-know-it-alls?highlight=know%2Bit%2Balls

And everyone else, don’t be afraid to ask any question or start a cool thread to share.

The below is for all Agoners who didn’t even take the time to read the above links I provided. This is a part of a review of the Odyssey KISMET
By: Nicholas Bedworth

’If you describe your speakers and cabling beforehand, Klaus can dial in an appropriate setting for you at the factory.

Voicing your system for fun and pleasure: Over a period of several months, my Kismets drifted a bit towards the warm. But after taking a few moments to tweak the bias, everything was brought back to normal. Higher bias makes the Kismets warmer; lower bias cooler. A couple of millivolts make a noticeable difference.’

but an "audio" amp shouldn’t be "biased" to produce a particular sound. That IS what tone controls are for, if you need those or want them in the signal path. Biasing can be done in a closet. Biasing an amp in a particular "setting" to tune the amp is just garbage if someone is claiming that.

Guitar tube amp biasing tweaks are NOT for audiophile situations.

Hey skippy, If you took the time to read my thread AND the attached links your smartass may have realized I nor Nicholas Bedworth were talking about guitar amps! This was not a horrible thread and I got two words for you. **** ***

Biasing an amp in a particular "setting" to tune the amp is just garbage if someone is claiming that. A "room" does not determine circuit design and unless you seek distortion, leave dials on the circuit boards where they are.

’Setting the overall TONAL balance to one’s personal tastes involves adjusting, for each bank of power transistors (there are two banks per amplifier), a bias and a balance precision trim pot. You’ll need an inexpensive voltmeter to measure the levels and a non-conductive alignment tool but with a little experimentation and practice it can be done in 2-3 minutes per amp. My online audio colleague Mike Galusha was exceptionally generous with his patient explanation and instructions on how to get the most from these controls. It is really not hard at all and the results are well worth the slight effort’. ’At 22 - 23mV, everything is just right at least in the context of my other equipment and ROOM’.

’Instead of accepting the TONAL balance as fixed to require swapping out gear to change it, one can instead HEAR in the same system a range of coloration including of course ’just right’ somewhere in the middle. With the bias set to lower levels around 18mV, detail and definiteness dominate the sonic experience, not a bad thing at all for some listeners. Every instrumental or vocal line is clearly audible as a separate entity. On the other hand the three-dimensional body of vocalists and violins for example is reduced and there’s a feeling of coldness and solidity but not necessarily dryness throughout. ’When the bias is set to the higher end of the range, say 27 - 28mV, the individual performers in a chorus or woodwind section become a bit congealed or unnaturally pushed together.’

@tray


I suspect you meant amplifier bias is when you are predisposed to prefer a favorite brand of amplifiers??