#1
I see soo many people refering to fixed bias as a bias that doesn't need to be adjusted. The amp companies really used a bad term calling them fixed. A fixed bias does need to be biased when replacing the power tubes.
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
Last edited by modernp at May 24, 2008,
#3
I'm not sure, but I don't think the usage of the term has anything to do with region. I think it's abused everywhere Could be wrong tho.

Oh, and btw, USA IS overseas
Quote by Lunchbox362
This thread if fail in almost every way imaniganable.
#5
Fixed bias means the cathodes are referenced directly to ground, and the bias is controlled by a separate bias circuit biasing the grids to a negative potential by a bias tap derived from the power transformer, as opposed to cathode bias which just means a big resistor and cap are connected from each cathode to ground.

Cathode bias means it can't be changed without circuit mods, wheras fixed bias should really mean that it's adjustable by a bias pot. On some amps though, like Mesas, they just whack a resistor in there and leave it, so you get a non-adjustable fixed bias amp. Adjustable is really a far better term.
The Laney Thread are big and clever. No exceptions.
#7
Yeah but soo many people here the word fixed and they think it doesn't need to be biased. Amps come in to our shop all the time because of it.
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#8
Quote by MrCarrot
On some amps though, like Mesas, they just whack a resistor in there and leave it, so you get a non-adjustable fixed bias amp.


That's what 'fixed' really means. Nowadays, with inconsistent tubes, you need to be able to adjust it.
#9
On my Rivera they code the power tubes. So all you have to do is order the same jj's as the code. And now they are starting to cross refence those codes to other manufacturers.
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#10
Quote by mr_hankey
That's what 'fixed' really means. Nowadays, with inconsistent tubes, you need to be able to adjust it.
That'd make sense, but I always assumed 'fixed' referred to the actual biasing system, I'd not heard of any other nomenclature for that method...
The Laney Thread are big and clever. No exceptions.
#11
What is nomenclature?
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#12
no·men·cla·ture
noun 1. a set or system of names or terms, as those used in a particular science or art, by an individual or community, etc.

and question:
so if mesas are nonadjustable fixed biased, then they aren't able to be modded to have an adjustable bias?
Gibson SG Standard + 18volt EMG-81 & 85
Mesa/Boogie Mark IV + Recto 2x12
Keeley Modded BD-2
Vox V847a
Quote by one vision
Bureaucrats gonna crat.

Recognised by the Official EG/GG&A Who To Listen To List 2008
#13
Yes, your definition is correct, but I use the term "fixed bias" to describe an amp that can't be biased without mods because it simply makes a lot more sense
Quote by Dave_Mc
I've had tube amps for a while now, but never actually had any go down on me
Quote by jj1565
maybe you're not saying the right things? an amp likes to know you care.





www.SanctityStudios.com
#14
Quote by MatrixClaw
Yes, your definition is correct, but I use the term "fixed bias" to describe an amp that can't be biased without mods because it simply makes a lot more sense


well that depends on how you look at it, cathode biased amps will adjust themselves within certain limits, which is why they aren't "fixed"

in fixed bias amps the bias is fixed by the circuit and won't change without user adjustments.
make Industrial and/or experimental electronic music? Join my group!

Last.fm
#15
Quote by Kid_Thorazine
well that depends on how you look at it, cathode biased amps will adjust themselves within certain limits, which is why they aren't "fixed"
WRONG

This terminology has been around for decades, long before you or I were born.
There is no "how you look at it" about this.



Fixed bias means the voltage relationship between the grid and the cathode is fixed. It's not dependent on the current through the valve. The voltage can be adjusted by the user, but not by the change of current in the valve.

Contrast this with Cathode Bias -aka- Self Bias where the voltage from grid to cathode varies depending on the current in the valve and the voltage drop across the cathode resistor.


Quote by MrCarrot
Fixed bias means the cathodes are referenced directly to ground, and the bias is controlled by a separate bias circuit biasing the grids to a negative potential by a bias tap derived from the power transformer, as opposed to cathode bias which just means a big resistor and cap are connected from each cathode to ground.
This ^
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
Last edited by SomeoneYouKnew at May 24, 2008,
#16
Quote by SomeoneYouKnew
WRONG

This terminology has been around for decades, long before you or I were born.
There is no "how you look at it" about this.



I see you completely misunderstood what I said.



WRONG

Fixed bias means the voltage relationship between the grid and the cathode is fixed. It's not dependent on the current through the valve. The voltage can be adjusted by the user, but not by the change of current in the valve.

Contrast this with Cathode Bias -aka- Self Bias where the voltage from grid to cathode varies depending on the current in the valve and the voltage drop across the cathode resistor.


This ^


this is essentially a more complex version of what I said. perhaps you should work on your reading comprehension before acting like an arrogant douchebag.
make Industrial and/or experimental electronic music? Join my group!

Last.fm
#17
Quote by Kid_Thorazine
I see you completely misunderstood what I said.


this is essentially a more complex version of what I said. perhaps you should work on your reading comprehension before acting like an arrogant douchebag.
I think I'll just do both.
Meadows
Quote by Jackal58
I release my inner liberal every morning when I take a shit.
Quote by SK8RDUDE411
I wont be like those jerks who dedicate their beliefs to logic and reaosn.
#18
Why does someone always have to come into a thread and start argueing just for the sake of argueing?There are kinder ways of making your opinions known.
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#19
Quote by UnsignedRecords
no·men·cla·ture
noun 1. a set or system of names or terms, as those used in a particular science or art, by an individual or community, etc.

and question:
so if mesas are nonadjustable fixed biased, then they aren't able to be modded to have an adjustable bias?

Couldn't access the dictionary. Thank you
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#20
Quote by UnsignedRecords
no·men·cla·ture
noun 1. a set or system of names or terms, as those used in a particular science or art, by an individual or community, etc.

and question:
so if mesas are nonadjustable fixed biased, then they aren't able to be modded to have an adjustable bias?

Thanks for the definition
Also, some amps with "non-adjustable" bias can actually be adjusted, or converted to adjustable bias, if desired. It just takes a bit more work, and the replacement of a few parts. Some amps really benefit, such as Boogies and Peavey 5150's, which are often too cold from the factory. Newer Fender amps (Blues Jr., Hot Rod Deluxe, etc.) can also sound much better, and let the tubes last longer, with adjustment.
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#21
^ cool, thanks, i knew some amps could get a pot installed or just a resistor value changed, just not sure on boogies.

oh, i also wasn't try to be an ass or anything, i second-guessed myself (the word i was thinking of was "colloquialism") and just ended up copying and pasting it )
Gibson SG Standard + 18volt EMG-81 & 85
Mesa/Boogie Mark IV + Recto 2x12
Keeley Modded BD-2
Vox V847a
Quote by one vision
Bureaucrats gonna crat.

Recognised by the Official EG/GG&A Who To Listen To List 2008
#22
You kinda gotta take "someoneyouknew" with a grain of salt. He does that alot. Hes right most of the time but comes off as a jerk in how he does it. Never had to bias or have an amp biased yet. My kustom has the auto cruise set up. Supposedly you dont need to match tubes or have it biased. Havent found any schematics to how it works and havent taken mine apart to check out the system. I dont use mine everyday so be a while before need any tubes for it.
#23
Point taken Thanks
Tom Anderson Hollow Classic
72 thin line tele

Barber trifecta fuzz
Mi audio Crunch Box
Clyde Wah
Barber Burn Unit
Ocean efx Texas deuce
Boomerang chorus delay
Barber ltd


1971 Pro reverb
Fender acoustasonic
Fender super champ xd
#24
Quote by SomeoneYouKnew
Fixed bias means the voltage relationship between the grid and the cathode is fixed. It's not dependent on the current through the valve. The voltage can be adjusted by the user, but not by the change of current in the valve.

Contrast this with Cathode Bias -aka- Self Bias where the voltage from grid to cathode varies depending on the current in the valve and the voltage drop across the cathode resistor.


+1

The term 'fixed bias' doesn't tell you anything about whether it can be adjusted by a pot or not. (I write "by a pot" since all fixed bias amps can be adjusted, even 'non-adjustable' ones like Mesas).

Quote by Tackleberry
You kinda gotta take "someoneyouknew" with a grain of salt. He does that alot. Hes right most of the time but comes off as a jerk in how he does it.

He may not put 'padding' on his posts, but he does give good advice.