The bias probe measures the cathode current flowing through that particular valve, whereas the RCA jack measures the bias voltage applied to all valves. You can't say that the bias probe 'is more accurate' because it's not even measuring the same parameter.
The whine problem is caused by an overheating +15v regulator under the chassis which is only very loosely related to the valve operating conditions. Change the valves if you like but it won't make that much difference to this problem.
dude, the problem in this amp is NOT about tubes, nor transformers... its all in the regulator feeding the digital reverb processor, and the channel switching system...
I have heard from many sources that the RCA jack is placed at an inappropriate spot in the circuit and will give an unreliable reading. I personally really like JJ brand tubes.
HI, Using your video I troubleshot and rebiased by 1990 and all seems happy at the moment. I discovered that there is some drift in that mAMP output. It is not "fixed" during use. Hope this is "Normal" ( 45.6 to 49.5 depending on output demands I place on the head.) Found a bad tube, too. Now I will put about 3-6 hours of playing on it to make sure everthing seems happy in there. Until a brand new set of virgin tubes arrive I;ve had to use a frankenquad, 3 of one, 1 of another, both 6L6 GC.
One other question. You're right about the trebly bit too. For a deeper bottom end in a rock crunch tone, would JJ tubes be better than Mullard EL34s, or the other way around?
I'm in Sydney Australia and I just bought myself a brand new 1990 Bugera 120watt amp. Guess what? After a short period of playing it, it flicks between channels - clean and dirty - and then goes off. When it cools, it automatically comes back on again. Exactly what you said! I am going to put some EL34 tubes in it, bias them, and see if this fixes the problem. Q. After doing this, should it be RELIABLE enough for gigs or are there other issues?
im havin a problem with my brand new bugera 1990, i was playin it on the 60 watt setting and it started to break up all wierd, then i went on the 120 watts and it started crakling and scretching witout my guitar plugged in.......... i dont know if this is the same problem.... help please
Maybe someone can answer this question. How does the power tube master bias adjustment pot recognize which tube you are working on? After biasing one tube wouldn't the next one being biased throw the other one off kilter? I am planning on re-tubing my 333xl and I have never done this- so my plan is as not to blow it up in the feeble attempt of fixing it.
@MaxxxwellC Maxwell hey thanks for this! 5881 tubes are not good audio tubes period.Cheap military versn of 6L6's/ I had posted this on UG and all the jocksbitched about itlike I am a dumbass,sure- I really like that the 1990 and 333XL are so easy to bias I am also using a bias testr (eurotubes) which I also got crap for mentioning the bias also. We'll see how long before they are over here cking the 1990 out which they claim sucks. I've paid my dues long ago, sounds like you have 2
great video. Me and my rhythm player are using these. He has not had this problem but I have once. Thank you roadies for packing the back up. One question what do you have your multimeter set at on the dial.
what the fuck?,that sucks,take it to a bugera dealer to have it fixed if its still under warrenty.Damm I havent any probs with my 1990 and Iv been playing every weekend 1 year straight with out changing a tube.
Thats cool man,I still have the bugera tubes in the power section to my bugera 1990,and havent had any problems.I havent replaced them in a while,and I play a lott of gigs with it at high vollume and the gain maxed out! This amp rules,..well mine does anyway.
Awesome slideshow! I bought one of these the other day and it has the same problem. I can't thank you enough- now instead of returning it and getting the same problem again, I will have them swap those tubes out. Thanks again!
Good Slide show - Only comment is that the plate voltage should be measure to be able to calculate the mA.( tube watts /plate voltage ) x 70% = mA. Tubes have different watts rating, in the case of 6L6GC it would be 30w.
Did you check the plate voltage?
omfgbbqsauce 3 weeks ago
Thank you! Very nice video!
DethVmnt 3 months ago
Hey do you still have the 1990?
theblazerzone 4 months ago
Hi Max! I have a doubt! Noob question indeed. Do you have to measure EACH tube with the bias probe? or only one of EACH PAIR? Thanks!
HeilTheOperator 5 months ago
I have a very noobish question:
I have a 212-cab with two outputs and an ohm-switcher (4,8,16) how do I have to connect it to the amp????
MetalAriel 5 months ago
Can I replace the stock tubes with EL34's?
JimmyF95 7 months ago
james hetfield thank you!
izzy92rock 7 months ago 3
The bias probe measures the cathode current flowing through that particular valve, whereas the RCA jack measures the bias voltage applied to all valves. You can't say that the bias probe 'is more accurate' because it's not even measuring the same parameter.
The whine problem is caused by an overheating +15v regulator under the chassis which is only very loosely related to the valve operating conditions. Change the valves if you like but it won't make that much difference to this problem.
olsmokey 8 months ago
@olsmokey well hey, im replacing my tubes soon, which one should i use, the rca port or use the bias probe? i need my tubes to last a while
89GlamMetal 4 days ago
you sound EXACTLY like James Hetfield..
gerby90 8 months ago
dude, the problem in this amp is NOT about tubes, nor transformers... its all in the regulator feeding the digital reverb processor, and the channel switching system...
sergioajaimes 8 months ago
Hello Maxwell,
I am a Dutchman and have a questionb for you (maybe a stupid question?).
Why do not you use the RCA spot beside the potmeter?
I have a new V22 and maybe have to change the EL-84 tubes someday. And which are a good brand preamptubes? There are three 12AX7 in the V22.
Thank you in advance.
Henk
HenkDynacord 8 months ago
@HenkDynacord
I have heard from many sources that the RCA jack is placed at an inappropriate spot in the circuit and will give an unreliable reading. I personally really like JJ brand tubes.
MaxxxwellC 8 months ago
your voice sounds like Brian the dog from Family Guy :P cool xD
MsNevermore 8 months ago
HI, Using your video I troubleshot and rebiased by 1990 and all seems happy at the moment. I discovered that there is some drift in that mAMP output. It is not "fixed" during use. Hope this is "Normal" ( 45.6 to 49.5 depending on output demands I place on the head.) Found a bad tube, too. Now I will put about 3-6 hours of playing on it to make sure everthing seems happy in there. Until a brand new set of virgin tubes arrive I;ve had to use a frankenquad, 3 of one, 1 of another, both 6L6 GC.
sustayne 9 months ago
can i replace the stock tubes with lets say kt88's or 6l6's even though it comes with 5881's, as long as i bias properly?
dashizzler 9 months ago
@dashizzler
6L6 yes, KT88 no.
MaxxxwellC 8 months ago
Oh and 2 question!
How's your bugera doing?
Will the amp work only rebiasing and not changing the tubes? Cuse it will take a wile for me to have the money for a new set of tubes.
andreisidro 9 months ago
what the fuck dude! you didnt let us hear the finished product,grrrrrr
hirskdubbi 10 months ago
is this the golden voiced homeless guy narrating?
jfr04 10 months ago
why did you by a bias probe, my 1990 has a rca bias spot and an adjuster right next to the far left power tube, and so does yours.
christianguitarest 10 months ago
@christianguitarest
The Bias probe is much more accurate.
MaxxxwellC 8 months ago
@MaxxxwellC Good to know, Ill have to try one out, its good to have an accurate bias.
christianguitarest 8 months ago
WE HAVE FOUND THE NEXT GOLDEN VOICE
nuuuum 11 months ago
One other question. You're right about the trebly bit too. For a deeper bottom end in a rock crunch tone, would JJ tubes be better than Mullard EL34s, or the other way around?
Mrjohnfstuart 11 months ago
I'm in Sydney Australia and I just bought myself a brand new 1990 Bugera 120watt amp. Guess what? After a short period of playing it, it flicks between channels - clean and dirty - and then goes off. When it cools, it automatically comes back on again. Exactly what you said! I am going to put some EL34 tubes in it, bias them, and see if this fixes the problem. Q. After doing this, should it be RELIABLE enough for gigs or are there other issues?
Mrjohnfstuart 11 months ago
im havin a problem with my brand new bugera 1990, i was playin it on the 60 watt setting and it started to break up all wierd, then i went on the 120 watts and it started crakling and scretching witout my guitar plugged in.......... i dont know if this is the same problem.... help please
guitargod445 11 months ago
how about a before and after vid :)
lakerblake 11 months ago
so thats it? thats how you bias a bugera? just put the probe on one tube?
kodieperkins 1 year ago
Maybe someone can answer this question. How does the power tube master bias adjustment pot recognize which tube you are working on? After biasing one tube wouldn't the next one being biased throw the other one off kilter? I am planning on re-tubing my 333xl and I have never done this- so my plan is as not to blow it up in the feeble attempt of fixing it.
fistandantilus18 1 year ago
your voice is awesome
andrewkadar 1 year ago 10
@andrewkadar
Thanks man.
MaxxxwellC 1 year ago
@MaxxxwellC Maxwell hey thanks for this! 5881 tubes are not good audio tubes period.Cheap military versn of 6L6's/ I had posted this on UG and all the jocksbitched about itlike I am a dumbass,sure- I really like that the 1990 and 333XL are so easy to bias I am also using a bias testr (eurotubes) which I also got crap for mentioning the bias also. We'll see how long before they are over here cking the 1990 out which they claim sucks. I've paid my dues long ago, sounds like you have 2
BionicSam 11 months ago
@MaxxxwellC did your voice changed when u used steroids?
pietershertogen 9 months ago
Will EL34's work for the 1990? If so how is the sound comparison?
lakerblake 1 year ago
great video. Me and my rhythm player are using these. He has not had this problem but I have once. Thank you roadies for packing the back up. One question what do you have your multimeter set at on the dial.
SixMinutesIn 1 year ago
So, do you go through this process for each tube or do you just set bias using one tube and it applies for all?
pupstop1 1 year ago
@pupstop1
Great question. It applies to all of the tubes, so you only do it once.
MaxxxwellC 1 year ago
thanks man i have 6262 and im gonna do this hahahahaha
Lubial 1 year ago
just 4 likes?wtf :O
this vid is so helpful!
megadv8r 1 year ago
Hi friend! What preamps tube i have to buy for great sound? Tungsol? Sovtek? And finals? Thanks...
Slashgj88 1 year ago
@Slashgj88
My vote is for JJs.
MaxxxwellC 1 year ago
@MaxxxwellC Good call
Theyweredoingsome 1 year ago
what the fuck?,that sucks,take it to a bugera dealer to have it fixed if its still under warrenty.Damm I havent any probs with my 1990 and Iv been playing every weekend 1 year straight with out changing a tube.
zalliwa 1 year ago
I did this exact procedure in a Bugera 1960 head and while I was adjusting the bias the amp made a pop sound through the speaker cab...
All the tubes light up but I am no longer getting any sound through the cab inputs...
JBL8863 1 year ago
Thats cool man,I still have the bugera tubes in the power section to my bugera 1990,and havent had any problems.I havent replaced them in a while,and I play a lott of gigs with it at high vollume and the gain maxed out! This amp rules,..well mine does anyway.
zalliwa 1 year ago
do you like this amp? if i got a Bugera this would be the one i would get
RowenCx4 1 year ago
Is this problem only on the 1990 or do the other bugera amps have the same problem.
shanecook9 1 year ago
Awesome slideshow! I bought one of these the other day and it has the same problem. I can't thank you enough- now instead of returning it and getting the same problem again, I will have them swap those tubes out. Thanks again!
Thesoundnet 1 year ago
@Thesoundnet
Great man. Make sure the amp gets re-biased when they change the tubes and they use a bias PROBE and NOT the little bias plug that's in the amp.
MaxxxwellC 1 year ago
you got james Hetfield's voice!!! LOL
nice vid btw
caiide 1 year ago
Good Slide show - Only comment is that the plate voltage should be measure to be able to calculate the mA.( tube watts /plate voltage ) x 70% = mA. Tubes have different watts rating, in the case of 6L6GC it would be 30w.
Magiamusical 1 year ago
I disagree somewhat with the Bugera tubes, I have a V55HD, and i still have the stock 12AX7s and 6L6s in it and it sounds great.
I havent had ANY problem tubewise so far.
The ONLY problem I have had with this amp is its jumping channels, after an hr of use.
Once Behringer fixed the 15V regulator responsible, not 1 problem since!
Still a good vid.
DO you do voice over work? Cos you got a good radio or TV voice.
ace69er 1 year ago
fascinating stuff, Maxxx.
(Paul from Facebook)
crushme99 1 year ago