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Post subject: Re: fixed bias amps.
Posted: Thu Nov 15, 2012 1:58 am
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Thanks Bill. Different strokes for different folks. All's good.

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Post subject: Re: fixed bias amps.
Posted: Thu Nov 15, 2012 7:02 am
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Roger that. :wink: :D

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Post subject: Re: fixed bias amps.
Posted: Sat Jan 04, 2014 8:42 pm
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Hello ,

I am new to the Fender forum and just purchased a Fender Supersonic 100 combo. I hope you guys could help with a couple of questions I have. I tried to research these questions in the manual and here on the forum when I came across this thread.

My questions are:

1) Regarding the auto-bias feature, I read on this thread that there were seven adjustments via the back panel:

" Whether the Fender Bias Point is too "COLD" or too "HOT" for you is irrelevant as firstly that is a personal preference and secondly this amp actualy has 7 bias selections. COLD - * - * - WARM - * - * - HOT. The normal setting being WARM which is probably where the standard values on the schematic are based upon. But as I said earlier, a little mod can be done to have this amp BIAS range running a lot hotter and then you would not need to adjust it ever again. Just think of the AUTOBIAS as a little "you" continuously checking the bias to keep it spot on even while your playing."

I could not find any reference to the 7 bias selections in the manual and wanted to ask if this is verified, and if so, how do you cycle through the 7 selections? I assume you press the cold or hot button multiple times?

2) The second question is regarding the Stadium/Club options. I understand that Stadium equates to 100 watts and Club to 25 watts. However, when I use the Club setting, it seems to me that my amp is louder than when set to the Stadium setting. Has anyone else experienced this? Could my particular amp have been wired in reverse? This amp is really loud, and I was hoping the 25 watt setting would make it more usable in situations requiring less volume.

Thanks in advance for any help with my questions! :)


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Post subject: Re: fixed bias amps.
Posted: Wed Dec 03, 2014 2:33 am
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I have had a Fender supersonic head in my workshop for 2 months , to resolve an issue of shutting down the clean channel after about 50 minutes of playing. After reading all of the forum notes I had decided to test the all of the components in the bias circuit and attached ribbon cable. the result was that no component had failed. My gut feeling had been that the amp chasis was hot at the point of shutdown. After checking the temperature at the point of shut down the steel chasis sat at 55 degrees celcius and the power transformer sat at around 58 degrees celcius. It was clear to me that failure was due to the lack of ventilation within the component/ integrated circuit cavity, especially around the bias circuit that sits above the power tubes. From this point it appeared simple to me , I reflected upon old school amps like the Arbiter Sound house 120 watt and Hi watt amps that had routed out channels above the power and preamp tubes. I eventually ended up cutting 2 120mm long x 20mm wide channels above the 4 power tubes and 3 preamp tubes, and set a pressed expanded aluminium grill onto the top of the cabinet. The result is that the amp runs over 3 hours at an ambient room temperature of 35 degrees celcius . Ps if you place the amp on its head without any changes it wont over heat any will run 24 - 7. Its a happy ending and a resolve to that cool sounding amp.


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Post subject: Re: fixed bias amps.
Posted: Wed Dec 03, 2014 4:02 am
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Good job Timbo95. Although, I don't recall anyone else having heat issues with this amp. Really, 58 C is not unusual for a tube amp with this many tubes. Maybe you are onto something here, the placement of the bias circuit in relation to source of heat. :idea:

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Post subject: Re: fixed bias amps.
Posted: Wed Dec 03, 2014 4:56 am
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shimmilou wrote:
. Maybe you are onto something here, the placement of the bias circuit in relation to source of heat. :idea:



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Post subject: Re: fixed bias amps.
Posted: Mon Dec 15, 2014 10:01 pm
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Bugera/Behringer amps have a circuit named "Infinium".
It is a bias auto sensing and auto adjusting technology.
Bugera says/claims that the system monitors EACH tube individually and adjusts the bias to be a "optimum".
What that "optimum" setting is is obviously decided on by the circuit engineer/s.
This system works over the life time of each power tube adjusting it's bias even as it ages.
Bugera claims this circuit can extend tube life by 20 times. That's a hefty claim, and pretty darn good if it works as they claim.

I think it's pretty darn impressive technology and I welcome it. Guitar tube amp technology has been around for a very long time and it's cool that someone finally designed something to bring tube tech into the modern era. This technology makes sense.
Some may lament that they can't now "tune" their bias to what they like.
But then if you like the amps tones as they are designed, then this tech will help keep that tone over a longer life span of the power tubes.
Many of us of course like to tinker. :)

I had the Bugera TripleRec amplifier with this technology. It was a very technologically impressive amp with it's auto bias along with SS recitifier, tube rectifier, or a combination of both.
I swapped power tubes in it to see/hear what it would do and it responded great to any power tubes and different tube combinations, which is pretty cool if you want to mix and match.
Put in different tubes and the auto bias led's would flicker for a few seconds and then settle it.
It's a little light show to apparently show you that it's doing something.
It has 3 independent channels each with their own eq along with 3 different voiceings per channel, and a continuously variable power output from 1 watt to it's max.

Pretty cool amp IF you like it's tones. After a month with that amp I concluded that it wasn't what I wanted tonally. But I sure do appreciate Bugera's technology and willingness to try something different.
I actually like their V22 and V55 amps better as they are voiced more "old school"/vintage.
Those amps have the infinium tech in them as well. I think all of their amps now have infinium.

But, here I am with 2 new regular ol' Fender amps with nothing fancy about them, and I prefer the tones and feel I am getting from them.
Sometimes the old tried and true just works, even if they are not still hand wired. :)
Still, I wouldn't mind a continuous auto sensing/auto biasing circuit in my Fender amps.
Fender amps can use some modernizing as long as they keep their basic tones, but then I'm sure that's where it gets tricky. If you fiddle with the design, then you invariably alter the tone, which is why vintage Fender amp lovers don't much like the new PC board Fender amps.
Luckily for me I really like my new PC board 68 custom amps.


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Post subject: Re: fixed bias amps.
Posted: Tue Dec 16, 2014 1:11 am
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That's amazing! I routinely get 10 years or more from my tubes, and Bugera can extend that to over 200 years?

Wow! :o

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Post subject: Re: fixed bias amps.
Posted: Tue Dec 16, 2014 5:18 am
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Any schematic how Infinium circuit look ?


http://www.guitarworld.com/review-buger ... -amplifier


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Post subject: Re: fixed bias amps.
Posted: Tue Dec 16, 2014 8:59 pm
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shimmilou wrote:
That's amazing! I routinely get 10 years or more from my tubes, and Bugera can extend that to over 200 years?

Wow! :o


:)
I'm sure their claim is quite likely exaggerated, marketing you know.
The claim is likely comparing the average user and tube life, and maybe even worst-case scenario where the amp is never tuned up.
Most players probably don't keep their amps tuned like you do.

Over the years I've known regularly gigging tube amp players and their tubes don't last 10 years when they are cranking them regularly.
For those of us who don't gig regularly anymore playing mostly at lower power/volume levels helps those tubes live longer.


Last edited by Rverb on Tue Dec 16, 2014 9:06 pm, edited 1 time in total.

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Post subject: Re: fixed bias amps.
Posted: Tue Dec 16, 2014 9:05 pm
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stratele52 wrote:
Any schematic how Infinium circuit look ?


http://www.guitarworld.com/review-buger ... -amplifier


I'd like to know how it's done too.
I've read non tech info saying that it's a "processor" controlled system.
How it's actually implemented and wired would be cool to see.


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Post subject: Re: fixed bias amps.
Posted: Wed Dec 17, 2014 2:11 am
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Rverb wrote:
stratele52 wrote:
Any schematic how Infinium circuit look ?


http://www.guitarworld.com/review-buger ... -amplifier


I'd like to know how it's done too.
I've read non tech info saying that it's a "processor" controlled system.
How it's actually implemented and wired would be cool to see.


Sure it is something close like a processor.

I wish there is no problem with this amp in futur , working with those circuits may cost more than a " standard " amp . You 'll loose what you save in tube , if what they said is true.


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Post subject: Re: fixed bias amps.
Posted: Thu Dec 18, 2014 12:50 am
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stratele52 wrote:
Rverb wrote:
stratele52 wrote:
Any schematic how Infinium circuit look ?


http://www.guitarworld.com/review-buger ... -amplifier


I'd like to know how it's done too.
I've read non tech info saying that it's a "processor" controlled system.
How it's actually implemented and wired would be cool to see.


Sure it is something close like a processor.

I wish there is no problem with this amp in futur , working with those circuits may cost more than a " standard " amp . You 'll loose what you save in tube , if what they said is true.


That's exactly what I was thinking.
That "feature" may prove to be costly to fix.
And if there isn't way to bypass it and be able to adjust bias manually, then the owner will have to pay for that fix.
The costs of progress. :)


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Post subject: Re: fixed bias amps.
Posted: Thu Dec 18, 2014 2:06 am
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Rverb wrote:
[
That's exactly what I was thinking.
That "feature" may prove to be costly to fix.
And if there isn't way to bypass it and be able to adjust bias manually, then the owner will have to pay for that fix.
The costs of progress. :)



+1


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