MartyGrass Posted December 31, 2013 Author Posted December 31, 2013 Well, hello there. That's interesting. Tell us about it.
t0aj15 Posted January 1, 2014 Posted January 1, 2014 Wow. If that amp was any smarter it would be solid state! But if it were solid state it wouldn't have thirteen tubes.
t0aj15 Posted January 1, 2014 Posted January 1, 2014 Well, hello there. That's interesting. Tell us about it. Excuse me are you being facetious yet again?
bolero Posted January 1, 2014 Posted January 1, 2014 I've heard good things about those supersonics haven't had a chance to try one though
H Posted January 1, 2014 Posted January 1, 2014 Excuse me are you being facetious yet again? Mark doesn't do 'facetious'. He's doing 'interested'. Here's your time to tell us how this amp does its biasing. I'm interested too - didn't know Fender had this technology too.
MartyGrass Posted January 1, 2014 Author Posted January 1, 2014 Mark doesn't do 'facetious'. He's doing 'interested'. Here's your time to tell us how this amp does its biasing. I'm interested too - didn't know Fender had this technology too. Yeah. What Howard said. I sometimes plummet to the land of sarcasm but try to avoid that on the net. Without eye contact it is too easy for miscommunication to happen. I was aware of adjusting bias but had not used tube amps for such a long time I hadn't even thought about it for a long time. I now get the general idea of why someone may want to do that adjustment. For me, that's an adventure for another day.
t0aj15 Posted January 1, 2014 Posted January 1, 2014 Here's your time to tell us how this amp does its biasing. I'm interested too - didn't know Fender had this technology too. To be honest I don't have a clue how they do it, but I know it involves digital technology (for the biasing) which does not invade the signal chain, but rather controls the voltage control circuits that control the balance between the actual audio output tubes, in this case 6L6's. Perhaps an actual EE could step in and explain it to us all. Tube bias to me has always been one of those factors that I've always known or at least 'felt' to be immensely important until now. Now I know that when it comes to tube amps it is THE most important factor of a really GOOD amp.
TalismanRich Posted January 1, 2014 Posted January 1, 2014 I found this on the Fender Lounge. The amp has multiple settings, so you can adjust the bias to be hotter but I'm sure they set up the range to be well within safe limits. There are some high end audio amps that appear to use similar technology. it monitors the milliamps/millivolts like your probes do and maintains that value via a microcontroller which pulswidthmodulates a transistor to generate the bias voltage that you would normally do via a potentiometer. Fender would have pre-selected their optimal bias values for the 3 bias selections, but the amp will maintain those values automaticaly what ever they are. If the NORMAL setting is somewhat "COLD" based on what you would like then there is a "HOTTER" setting. Ofcourse wether it is hot enough would have to be measured. But assuming the desired bias can be achieved via the selector switch, then the "Autobias Unit" would constantly maintain that bias regardles of tube grade. If the bias is too cold and cannot be made hotter, then a "Potential Divider Mod" would be required in the "BIAS FEEDBACK LOOP" to trick the processor into running "HOTTER", but once done the BIAS will always be maintained.
t0aj15 Posted January 1, 2014 Posted January 1, 2014 I found this on the Fender Lounge. The amp has multiple settings, so you can adjust the bias to be hotter but I'm sure they set up the range to be well within safe limits. There are some high end audio amps that appear to use similar technology. If you read further up in this thread you will see that I already tried to make that clear. That in addition to allowing you to select the DAMPING factor (as I also said) was a primary reason for me selecting this amp over several others I was considering. In addition, in talking to the Fender folks in Phoenix I was able to zero in on the proper ratings of the 6L6's that are wanted/desired with this amp and got a 'proper' set of back-up power tubes................so I think I'm set at least for a while.
Trouble Posted January 3, 2014 Posted January 3, 2014 Well, I am a bad person and this post is just here to show you what you can get away with rather than what is the correct thing to do. Probably dont do what I do. I flick the power and standby switches on and off at the same time. I leave the amp running for hours. Sometimes unattended for extended times. I just pull the guitar lead out a little bit at the amp input. Ive done this for nearly 28yrs with one amp. Ive put a full set of tubes in it three times over that period.(other than goofing around trying out different tubes) Not because I had to but because I thought I should. About the only thing that Ive done "right" is to allow the amp to cool down for 5minutes before moving it. I wouldnt do this to anyone else amp. With my super reverb the switches are in the back, for years it sat in the same spot against a wall, I would reach back and flick them on at the same time, leave it on for hours, sometimes days when the jewel bulb was burned out, and it has had the same tubes in it for about 15 years and still going strong. The only thing it's had going in it's favor is I haven't moved it around much. Not recommending this practice to anyone anymore than Jeff is just saying they are not quite as delicate as people seem to think. That said, I had a cricket/grasshopper get in my little Vibro Champ and catch on fire, no real damage to the amp other than a weird smell for a couple days, but probably could have done some damage I guess. Anything can happen.
Trouble Posted January 3, 2014 Posted January 3, 2014 Here's how do the bias adjustment. Yes, boys and girls, someone will get hurt doing this. That adds to the excitement. Note the teacher discusses keeping one hand in the pocket at all times when in the amp but doesn't do it. I'm sure I'm the same way when I get comfortable around danger. No relevance to the thread but that is the same meter I have. I do like having a standby switch for switching guitars and taking breaks at gigs, other than that never really worry about it.
bolero Posted January 3, 2014 Posted January 3, 2014 No relevance to the thread but that is the same meter I have. ....wow, isn't that a fluke??
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