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

@tray


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

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.’

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.

Somehow this OP seems disingenuous to me. But maybe that's my bias!

Well, that about covers it.

@tyray
As fas as I'm concerned you can't go wrong with Klaus. He hooked me up with a pair of his Khartago mono blocks with Kismet boards inside. Told him what I had for a preamp and what speakers I had and he took it from there.

When the shipping company delivered them one had obviously taken a tumble down the stairs and was beat. It lasted a week before it gave up the ghost. Told Klaus and he shipped a new one out without hesitation.

I'm still new to this hobby too but between everyone here and vendors like Odyssey its a fun journey. I 2nd @kakomess' referral of Harley's book, The Complete Guide To High End Audio, is a great reference source.

What the heck did I just read?

Certain threads really need a warning tag of some kind.

@tablejockey,

Thank you!

http://ken-gilbert.com/images/pdf/taste_of_tubes.pdf

I’m not finished yet but the above pdf link is a damn good read!
Behind all that sarcasm you just maybe one cool ass dude!

Now don’t let that go to your head, as I have seen many of your one post comments - with no one having anything to respond to your (ouch) - shall we say thought provoking....Whatever.

Before I opened the link and reading some of the posts here I knew I was going to have to learn more about old vacuum tube theory since it is an early transistor. MUCH appreciated.

Bias adjustment on solid state amplifiers:

https://forum.audiogon.com/discussions/bias-adjustment-on-solid-state-amplifiers

Thanks @erik_squares and @tablejockey. Points well taken but what I’ve read in the above link from @ieales and even @monoogan not only does bias need adjusting at times but DC offsets may have to be adjusted too. I am not going to believe you - just because you say it is so. I’m here like everyone else trying to learn for myself.

Even though it may be easy to do, I will take @atmasphere’s advice and let a competent tech do it. Or maybe I’ll get one of my old vintage receivers in my old audio closet that we all have and start learning on my own, with the help of my neighborhood audio tech guy of course. And get me an audio 101 course book.

@kacomess,
Thank you

@jnorris2005,
He's the one who emailed me he does have specials and trade ins and to give him a call so we can talk about it...For the money, his customer service, 20 year warranty and quality of his amplifiers cost/performance value I have no problem buying used from the person who would personally go through to make sure it's right for me. If I'm not mistaken that's what he's known for...Beside I learned about his quality of his amps from here on agon from @patrickdowns.

Amplifier bias is when it only plays Genesis with Peter Gabriel well, but refuses to play Genesis with Phil Collins at all.

What the heck did I just read?

Go to the library and pick up a analog electronics 101 book.
Get an overview of electronics theory. 

Careful with all that audio jumbo jumbo.

The only reason to be concerned with bias, is if you're thinking of playing with tube amplifiers. Bias is simply voltage

If you want to enlighten yourself-
http://ken-gilbert.com/images/pdf/taste_of_tubes.pdf

I'll bet Klaus Bunge is scratching his head as we speak.

For technical details on all things audio, Robert Harley's book is very good (albeit now slightly dated).

@millercarbon

Good question MC, from what I gathered bias is ’something that can be dialed in an amplifier that can be HEARD.

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 amplifier. Bias level pots are the ones near the big central caps, the offset pots.’ This is per Nicholas Bedworth of six moons.

My background is structural, concrete, structural steel and rebar. Electrical engineering was not part of my informal training but believe it or not, with folks here on agon like millercarbon taking the time to help and explain albeit NOT in layman terms what things in audio are - like bias, some of this stuff is making sense and finally sinking in. Even if it’s only on my terms of understanding.

I guess I had a aha moment and not learned (at first) what it is, but with a solid state amplifier I learned HOW TO ADJUST BIAS MYSELF with an inexpensive voltmeter we all have around the house.

Also keep in mind I’m a newbie trying to share with other newbies in newbie like terms.

Although with my structural background I could probably design one heck of a mean concrete audio stand! With characteristics very similar to the look and finish of those concrete kitchen countertops you see in the magazines.

millercarbon I must say I was surprised you gave a wikipedia, cut and paste like answer! That is entirely not like you! :)

Thanks millercarbon for taking the time to help explain what bias is.

Was there supposed to be something in there about bias? Maybe you forgot to include it? Because I'm sure not seeing it.

Was it anything like this?
https://robrobinette.com/How_to_Bias_a_Tube_Amp.htm