How to Bias Your Guitar Tube Amp
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- čas přidán 1. 02. 2013
- A quick tutorial on how to set the bias on a guitar tube amp, specifically the Fender Hot Rod Deluxe.
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I managed to switch my tubes with this video and set the bias myself. Thanks for being very thorough and giving safety warnings, which I think a lot of videos out here lack. It was actually very easy to do. My amp sounds like new again 👌🏾😄
I wanted to drop by and say "thank you" for this informative and easy-to-follow tutorial. This saved me some time on restoring my amp, and I learned something new. Thanks again! :)
“I’ve got one hand in my pocket, and the other is biasing.”
- Alanis Morrisette
Ive got one hand in my pocket and the other one is jerking my girlfriend off
EXCELLENT!!! So glad you did this tutorial. I didn’t want to take my HRD to a tech for such a simple maintenance task. You shed light on the mystery.
Thank you for this! Your short video was more helpful than anything I’ve read in the forums.
really appreciate your effort to make these guides. Very well explained!
Thanks for the knowledge, this makes it much clearer for me. I always thought that if I didn't set the bias pot to the "absolutely correct" spot (that could only be derived at through an engineering degree) I would blow the amp up entirely. Thusly, I would until recently only buy solid state amps because I didn't want to get someone else to bias my tubes. Now I am learning to do it myself, and this vid provides a nice piece of the puzzle.
Thank you for the education on biasing the power tubes. I have a Hot Rod Deluxe and I'm replacing all the garbage GT's with JJ's (both preamp and power) but never knew anything how to check the bias. Looks simple enough, thanks for the video and safety tip!
Kennis, want to say thank you for sharing your knowledge on this. I just bought a FHD and it was so flat and dead sounding. Bought a set of matched JJ's and with your help got them biased to were I am so happy now! What a difference :)
super helpful and straight forward video! looking forward to getting amongst the tubes in my deluxe and having a go
Great vid. All the information I wanted and none of the filler. Thanks for the info.
I love your videos! Very informative, clear, and concise. Thank You!!
Thanks for the tutorial!!! Didn't know it was something I could do by myself...Amp sounds GREAT now!!!
Straight to the point and brought across very well, no Guru secrets like I always thought were involved, Thanx Kennis.
Great video, really cleared up my confusion with biasing. Thank you.
No, actually it's a crappy video, full of incorrect information.
Thanks Kennis. Great job making your tutorial easy to understand.
Great video tutorial. I really enjoyed the way everything was explained. Keep up the good work.
Most excellent! I wish all how-to videos were as well done and to-the-point as this.
Good stuff Kennis. I'm acquiring a USA HRD that most likely needs to have a total tube overhaul, and I'm just glad biasing can be done relative quickly and easily. Having no prior experience because all my other tube amps either have fixed bias (Mesa Boogie ROV25) or are self-biasing (THD Bivalve 30), so this video is super useful!
Ahh man THANK YOU!! Have been wanting to switch from SS to tube but this whole bias thing kept me from doing so. Finally got myself a HRD iii and could not believe this is all there was to it!! Thank goodness I have the potentiometer!! Thank you!!!!
Great video. Exactly what I was looking for. Thank you.
Great video! Very informative and easy to follow.
Thank you for a very instructive video. Changed tubes in my Fender HRDx and set bias to 71....it's like a new amp....
Great video for someone who knew nothing about biasing tubes! Thanks!
Remember driving thru Mississippi in the 70's. Bias was set high there.
Great vid, thanks.
Just a few clarifications .. Unless your amp is horribly defective (and blowing fuses) the circuits ARE already biased .. What you're doing is adjusting, measuring and/or optimizing the existing bias voltage/power dissipation. Secondly, one must be careful with that term "self bias". "Self Bias" DOES NOT means that you can adjust the bias yourself. Self bias is also known as Cathode Bias. It's referring to the the tube creating it's own bias by virtue of the cathode being lifted from ground via a cathode bias resistor. Outside of replacing the bias resistor with one of a different value, you cannot adjust this bias scheme. The other common method of biasing the output tubes is called "Fixed Bias". This method frequently utilizes an internal potentiometer that allows one to adjust the bias voltage to the output tube(s). This is called fixed bias.
Excellent video - professionally done !!
Awesome info Kennis. Thanks for making this.
Thanks! This works for my Fender Blues-Deluxe Reissue as well - same test point and pot locations.
Cheers! Seems a lot easier than I expected! Good idea hand in pocket rule.
Great video! Thank you, for this! About too go bias my hrd, and now i know exactly what too do
Greatly done and very informative
What do you not do? CHEAH!
I've got one of these amps, so this video was very helpful. Thanks very much
Thank you , that was really educational and concise ,, it helped .
Very explicite, helpful and friendly help sir! I'm changing my tubes for the first time today (Traynor YCS100).
Thank you for posting this video. This really helped me feel more comfortable changing out the power tubes from 6l6 to 6v6 for my Hot Rod Deluxe!
Not recommended.
www.tdpri.com/threads/6v6-and-6l6-interchangeable.52593/
You put 6V6 tubes in to replace 6L6s? I hope you get 5 minutes out of them. And I don’t really understand why anyone would want to do that in the first place?
On an interview the tec guy for Angus ACDC said he runs the valves hot.bias high a bit on the edge...which explains Angus,s eq only on 3 bass treble & mids...great info
Thanks...you have saved me a few quid...and amp down time.
Very Nice introduction to biasing. Thanks!!
That was very informative. Thanks!
That bias point is total cathode current.. A little screen current (5%) is included in that number..
So a number like 70mV at the test point is ~ 66mA plate dissipation for two tubes or 33mA for each tube. The B+ voltage with a cold bias (60mV) is 431V. A little OT loss and you have 429V plate. Multiply Volt with mA and you get the plate dissipation at idle. This is 14.16W or 47.2% of max plate dissipation for a 30W 6L6GC tube.. That is too cold,, you want to be above 50% to avoid crossover distortion. Between 50% and 60% is a good number for the hot rod.. Going higher and you will loose a lot of headroom and spank in the bass..
Lets run the bias to 80mV at the test point..
deduct 5% as screen current = 76mA of total plate dissipation.. Multiply with you plate voltage which should be a little lower as you are drawing more current at idle.. So lets say it has dropped to 424V (80mV) from the previous 429V (60mV).
Now you get an idle plate dissipation of 16.11W which is 54% of max dissipation.. That should be a good bias...
With the Hot rod deville you want to have a lower mV number at the bias test point as the voltages are higher in that amp..
With 60mV at the test point and correct wall voltages and a pair of 30W 6L6GC tubes you should get around ~484V on the plates..
Doing the same math you get that 60mV is 57mA plate dissipation (I assume 5% screen curent). Plate dissipation is (0,0285A x 484V) = 13.8W dissipation (or if screen current is even lower) around 14W which is 46.6% of max dissipation.. Again a little too cold.. Bring it up to 55% if you have a strong 30W 6L6GC tube..
thanks man , you took some worry out of my life lol now my amp sounds great and has been running good.
Thanks for this... I recently purchased a new Fender Blues Deluxe to replace a 15 year old model that quit working. The new one breaks up/distorts at 1-2 where as the old one would begin to break up at 4-5. I need the amp to play clean (jazz/traditional blues) with my hollow body guitars. This was a good video, a starting point to get the new amp set up to match the old one.
Perfect, thanks. Makes sense and I just happen to have a Hotrod Deluxe so I may just tweak before tomorrow's gig.
Thanks for the good instructional videos
Thanks, very informative and good job explaining.
i really like your tutorials,you're easy to listen to and learn,have you ever looked into an orange amp? do you think it's gonna be similar to bias like you did on vid? thanks
Great video. Exactly what I needed to know. Thanks for posting. Subbed.
Nice video as always thanks Kennis
Very easy to follow. Thank you! Never BIASed my Hot Rod Deluxe in 4 yrs I own it. The meter was showing 55. Damn!!
Thanks for clear information!
Great video. Thank you. Just getting into this
Thank you so much!
I have Blues Deluxe Reissue I remember it looking the same internally.
Any suggestions on cost effective power attenuators? I live in a small apartment...
sooo awesome. definitely help me a lot!
Really helpful video. Thanks!
Very informative video. Thanks man. If you have 4 power tubes, when checking the bias test point would the minimum be 120 instead of 60? Or is 60 just for this specific amp?
Thanks for the great tutorial! I'm wondering about lowering power? I have a Fender Concert Reverb with a 1/4 power switch. Is there any way to get this thing to 15 or 20 watts safely? I've heard of running on input 2 as well as 6V6 tubes? Different pre-amp tubes? Thoughts? Experience?
i just got that very amp second hand , your video was very helpfull thaks alot!!!!
thanks dude, this really helped!
Thanks Kinnis! I'm wondering if the 70mV setting is across the board - or for 6L6s - or for the Deluxe. I've got a Hot Rod Deville 212 and wonder if the 70mV would be the same for my amp? Also, my Fluke 75 has a DC 300mV setting, but not a 200mV. I'm thinking it would still put me in the right range. Thanks for the video and advice.
very useful video. That is just great. Thanks a lot.
Very clear thank you!
thanks for you info straight to the point A+
I'm gonna bias my Fender HotRod Deville 212 tonight, thanks to this movie!!
Thank You great tutorial.
This is really easy! Thanks
Big thanks for that video!
Great video. Thanks!
Helpful. Good video, thanx
Really helpful. Thank You
very good video, thanks for posting
this is great, thank you for this video
Very helpful.
Great video. Fender sets this amp at 60mV. Raising it to 70mV gives a better sounding gain. Higher bias shortens valve life.
Great video! Thank you!
That works out real well if one has an adjustment and test point. I haven't looked in my Carvin so I can't say how it's set up, everything sounds fine but it is a older amp so I expect to be servicing it soon, my Bugera is suppose to self baising.
Hey Kennis great video and really informative , I have a question, I use a fender SuperSonic 22 and just replaced my power tubes with jj 6v6s (2ea) and my preamps are jj ecc81( 2ea), and ecc83s (3ea.) would you know the bias value for this amp? I've been trying to get a hold of fender with no response's yet. Thanks
You have explained so far better then anyone else.
Outstanding Class ... Thank you.
Thanks for the information
thanks for "the hand in the pocket rule", as a self taught electronics experimental person, never heard that one before
Wow great how-to explanation.
Is this about same for the Hot-Rod Deville 4x10 2x12 the 1st ones.
Great video if one of the pre-amp tubes blows do I need to change the whole set
Great vid thanks!
What setting do you use on the multimeter and can u also teach me how to drain a capacitor
Thanks very helpful video
Best bias video on ytube. Also helps that mine is the blues reissue which is basically the same amp your biasing.
Thanks, very interesting. I have a laney vc-30 and the clean channel is very quiet compared to the drive channel. This happened after a guy revalued it. Would I have a bad valve in the preamp?
great stuff for us. thanks
thank you.
do power tubes need to be replaced at the same time and if so , why ?
Good video, i have a doubt with my twin reverb 68, cause have a switch to A, Ground, Off and B. How i could put this to do bias?. Cheers from Chile
Thanks a lot ! Has every amp this bias point indicator (I have a Mesa B mini rectifier) ?
Hi Kennis, great video! .. i have the fender hot rod deluxe western version are they the same as the normal hot rod deluxes? I'm going to replace the valves myself but confused on the term "self-biasing" does that mean you can put the power tubes in and they bias automatically ? or do you still have to bias them? ...do you also ever need to change the 3 little valves?
your videos are really helpful thanks.
Dear Kennis,
Thank you for the great video. I own a Fender Hot Rod Deluxe III and followed your video closely. Everything is set correctly with the multimeter (200m DCV) but I only get 30mv from the bias testing point. When I turn the wheel it goes from about 10mv to 55mv. Do you know what the problem here could be?
I'm using an almost brand new pair of JJ 6L6s that replaced the original Groove Tubes.
Hi, great video. I have a Bugera V22 Infinium (with auto bias). It bursts the power tubes in days. Could be that auto bias is damaged? Thank you.
Thanks for all great info. I’d like to replace the original power tube from my Vox AC4C1 for a Mullard and,Honestly, I’d prefer not to bias it if I don’t need it.once my amp has only one power tube, do I need to bias it ?If i don’t bias it (just replace) how can I check if it is working properly ? Which are the evidence of bad functioning (that it should boas-noites it) ?Thanks !!
Great video !!! really helpfull.
Great stuff thank you
I have a crate blue voodoo 300h, this particular amp has 2 bias test points as well as 2 bias adjuments knobs on the rear of the amp.
how would I set my bias correctly for my 6 new Tung-sol 6550s?.
thanks for your help.
Thanks for the awesome video. Nice having amps with only a pair of power tubes and three pre amp tubes. Saves a lot of $$$ come tube time ahem Mesa Boogie Mark Series.
thanks Kennis. I've been playing guitar for years but just take the amp for granted. recently I bought a Blues Jr to run in stereo with my HR DV because i felt things were "lacking". great combo though... Changing out my stock power tubes for the first time as well so I'll look to see if my HR DV 212 has the bias option. Sound like I may have some fun. great info, cheers.