You absolutely can bias a 6L6 a good bit above 46mV. It all depends on the amp circuit design. My Egnater Vengeance can run a WIDE variety of power tubes, and can even run mixed pairs such as 6L6's and EL34's, or KT88's and 6L6's. Back to the bias. The Vengeance bias for 6L6's can run between 60-70mV are the Egnater recommended bias level. I experimented with bias mV cause it's so easy to do on the Vengeance cause the test points and adjuster are on the outside. You can even play the amp while the meter is connected and adjust the bias to hear which setting is giving you the tone you prefer. My 6L6's are set to around 62mV, higher didn't sound as good, lower didn't sound bad either. The problem with the 333/333xl is that the supplied test point is not measuring the actual current flow. But, it's at least a much safer method than going into the amp. Plus, a few mV's one way or the other doesn't make a lot of difference. So even if Bugera is copying Peaveys bias test design rather than Egnaters, it's at least going to give you a reasonable and safe setting. Those who want to get exact with actual plate bias settings have a legit concern, but a user isn't going to red plate their tubes or be too cold by using the mV recommendation from Bugera/Behringer. It won't be as exacting, but it'll get you right in the ballpark.
I do remember many, many years ago in photo school we were told NOT to touch the photographic strobes because of the oil. The only reason I would cover my hands replacing tubes might be breaking a tube with too much pressure. Great video.
The Bugera 333/333xl is NOT self biasing as someone posted below. The bias is not adjusted automatically. What is there is a base bias switch that allows you to select for either EL34 or 6L6 bias ranges, but the bias will not set itself automatically. You still have to either use the supplied test and adjust points to get to a reasonable bias setting, or you can go the more accurate route using actual circuit test points and use the bias adjust that's on the circuit. The amp is NOT "self biasing" or "auto biasing". Please, read the manual, and if you aren't familiar with working on high voltage and high current electronics that can kill you if you don't know what you're doing, then take it to an actual tech. It's not expensive and costs much less than what can happen if you fail. Either stick with the supplied test and adjustment points, or take it to a tech if you want a more accurate bias adjustment. Actual biasing by a pro tech won't cost more than $100, and should really be about half that as it doesn't take more than about 20 minutes for a pro. At $50 for a bias set that's like $150 per hour, most tech's don't get that kind of money.
lower the bias the more headroom you have also, I myself i have my bedroom amps 50 watters running i use soft break up tubes biased hot, what this means is at a little less than half volume my power tubes are breaking up where someone with medium breakup tubes would be well over half volume before there power tubes started break up, you can also tweak plate voltage and screen voltage but thats a whole other ordeal thats not necessary most of the time, hope i was able to help ya some
as far as i understand and can see from looking at the bugera line they are all self biasing which means you dont open the amp or have and bias pots to adjust the amp does this its self, however there are draw backs to self bias such as you cant bias the tubes to your bias number, example 6L6GC tube type bias set at 30mv would allow the tube to break up at a later point where 38mv to 46mv(never run over 46mv with 6L6GC) gives a quicker breakup (tubes run hotter)
Yes but you must pull the two outer tubes or the two inter tubes. that will cut yer power in half make sure the Oms are set for the right cab/ speaker. A/B Amps you can do that . Note a Class A amp you couldn't do that because it's not "push pull" power section.
some people think that because when you replace certain headlight bulbs in a car they explode if you leave skin oil on them but tubes USUALLY don't get as hot
it’s a bologny that you can’t touch tubes that comes from car headlight replacement where they tell you not to get finger body oils on the bulbs because these oils could burn onto the glass guitar tubes don’t get as hot !
Slamming the power switch off is 100% fine to do. Putting it on on standby just leaves the heaters on, and turns off the output... so basically the same thing as turning on the standby, just the heaters turn off also.
You seem to know what you talking about when it comes to this, but are all bugeras self bias? to be honest I don't even know what that means so if you could help me out and educate me that would be awesome
