Been using tube amps for 25 yrs and never truly understood how they work just loved the sound. Your series on tubes is second to none! Thank you so much for posting this and sharing your knowledge, it is appreciated. Looking forward to more.
I have a mk2 deville ( made in mexico) I fitted a fromel supreme kit ,and changed all the valve sockets to gold ceramic .I usually set the bias a 68 mv ,I also recently changed the first ax12 to a at12 ,this has made the volume much more controllable
Excellent instruction. Just got a HRDV 410 and walked through the steps. Fantastic result. Beautiful cleans for days and very silent even with single coils. Thanks very much.
Great video! Very helpful and informative. I've had my Deville for probably 10 years and I was never 100% happy with the gain/overdrive channel. It sounded.......raspy.....not smooth at all. I installed a Fromel kit, which made things better....but still....something wasn't quite right. I had the amp serviced/biased/etc. Again.....better, but not quite 'there'. So I found your video and did as you suggested. The bias was set at 58-59, and the blue trimmer was epoxied in place. I powered-off and carefully trimmed the epoxy. I set the bias to 68 (the alleged 'sweet spot'), let it warm-up and took it for a spin. Much better! I was more satisfied with the gain....definitely an improvement. I also thought the clean channel had improved as well.....I could hear a difference. I kicked the bias up to 70 and I'm happy with it. Looking forward to next band rehearsal.
Rob, was looking for a simple video for biasing a Vibrolux and came upon this one. Since I purchase tubes like I'm sure many below from you all, I was happy to find this video. Very well presented, clear to understand and a great help for dummies like myself. Thank you.
G'day Rob, I hope you've been well in this time of crisis. I'm 11 years or more late on this, but I guess it's better late than never. Amongst most of the Biasing for the Hot Rod Deluxe I've seen, I decided to follow yours because it is the most clear (visually plus the audio & explanations) I've just done my Hot Rod today .. with 101% confidence thanks to you. Just one thing which I thought is super important, for those non-techo's like me. .... that's the detailed settings of the multimeter. I had to go over your video a few times to be sure. Where you set the multimeter to "Volts" to take the reading of the plate behind the Bias adjust knob, but mentioned very little about changing the multimeter to mV when setting the actual Bias while at the same time looking at the mV readings. I was lucky I saw the different settings showing on the video for your multimeter and so followed. In my case every detail of the procedure is important. Hope this will help you help us (non-techos) for future video releases. Stay well and all the best. ru
Good. Point taken. I just bought a fender hotrod deville that had a very loud microphonic howl, seemed to be the first valve in line of the 3 small ones, was going to buy a complete new set, but then I just swapped the first to around absolutely perfect now. A good hint to try first.
hey, yes, all the solder connections are fine. I just thought it was strange that i couldn't get it under 73mV but i made a call to the store and they said it's perfectly normal. They offered me to return them in if i wanted, so they could give me another pairbut as you said 73mV is a nice value. Great vid by the way! nicely explained for electronica noobs (like me)
Great video, well done! I own a HotRodDeluxe and this thing is always frying tubes. I took it to a tech who claimed to have biased it correctly but two days later at a gig I only had one 6L6 working, glowing extremely bright amber, distorted badly on the clean channel (I only use the clean channel) until it died all together. This was back in '05. I have a tech friend install new tubes 'bout a year ago and bias it, and it distorted again. I bought new tubes and I'll use your vid to DIY. Thx
got the new JJs in the mail today and checked em out by swapping one position at a time, swapped V3 nothing put the original in. tried V2 still nothing, tried V1 which I suspected and got a low volume fuzzy tone even on 12, so I put another one of the JJs in the V2 position and she jumped back to life with even more tone, put the last new one in just to complete the set and i figure ill hang on to the one good one for emergencies till i get a few spares, Thanks again for your help
@TubeDepotTV i knew it was a legacy because of the bridge and the tremolo arm.... they´re just the best guitars for me, i have the legacy special model, and also have a deville amp... awesome combination... excelent tutorial i am about to do this to my amp, greets!
Thanks dude, great video, very well spoken and nicely put together! I'm just about to change the tubes on my Blues Deville and I hope I goes as smoothly as your video!
@TubeDepotTV thanks a lot! I ended up settling at 70mV, messed with it back and for for a while and 70 just seemed to be a good middle ground where i got the best tone without killing my tubes
Hi! great tutorial! I have a question, I have a old hot rod deluxe made in USA and I would like to know what are the valves you recomend me. I would like to change all of them. Thanks from Spain!
Thank you I found the problem it needs new tubes 1 overloaded due to the lack of electricity. I'll retube it & be careful of what is tied into the outlet before I plug it in. Thank you for your videos on tube amps & a walk though of my & many other peoples post.
Yeah, that makes some sense. After I watched your vid, I perused other utube biasing vids, and all the techs were touching the tubes and viewers were commenting the same thing I said to you (I guess I'm not as alone as I thought in my old thinking). It would be so cool if you could demystify this old wives tale by doing an unbiased test (no pun intended) using two sets of matched power tubes, one totally filthy, and one spotless.
thanks, I also tapped the reverb tank and could hear the springs through the speakers so thats working ok, it was bad timing too cause my Wampler tweed 57 pedal had just came in the mail and I was itching to try er out. Still in Awe over how many tools and tube accessories you have on the tubedepot store, wouldnt mind getting one of the 18 Watt british amp Kit sometime in the future.
Very Good Explanation! Glad you mentioned safety. Too bad for the Test Point - the PCB should have a Tip Probe socket for holding the DMM's probe. To minimize the chance of getting an electrical shock (although not UL approved/tested) I wear the Black thicker Mechanics "Nitrile Gloves". Love 6L6 amps like the Deville (I have a Peavey ValveKing 2x 6L6). A dab of Nail Polish or RTV/Silicone keeps the pot from moving after being set.
I so wanted to be a guitar god ... but sadly my playing has always been well below the "god" rating. Therefore, I had to find a real job ... enter electronics tech.
Brilliant vid and pickin ! The lad just picked up a HR Deluxe ii ....fantastic sound except the power tubes are noisy on some low notes. Gonna try some damper rings but if that doesn't work then may be putting your instructions to use soon with a pair of new tubes.
Hi Rob, Tube Depot, Just a little FYI, the ribbon connectors on the Deville can come loose and this will cause issues with the amp and performance of. El Paso Tube amps on TH-cam did a video about this problem, worth a view. Discharge filter caps first when working on amps, use only one hand when hooking up meter. Also see Uncle Doug on YT, very knowledgeable. Take care, C.
I played a gig last night with some band and the other guitar player's amp died on the gig...it was a Hughes and Kettner though....he came back 20 minutes later from his house with a Deville!
this was very informative, cleared up a few things for me. cheers mate much appreciated p.s guitar playing at the end was killer, should upload a video with just you jammin
At 1:23 you say to not touch anything without first discharging the amp. How is this done? Will simply turning it off and unplugging your amp discharge it after a period of time?
Mike Lowrey Well, probably, after a month.. I'm tempted to say "if you have to ask, don't do it." - Not to be snarky, but because it's actually dangerous. A power resistor is used to discharge the power supply filter caps. There's a lot of videos about it. If in doubt, take it to your tech.
I made a wand out of a cheap screwdriver, alligator clip and a 1k resistor. Alligator clip lead is soldered to the resistor, resistor to the Clip the alligator clip to the chassis, touch the end of the screwdriver to the positive end of one of the filter caps. That will usually discharge most caps in less than 10 seconds. They will discharge after turning the amp off while the cathodes are still hot enough to emit electrons. But don’t rely on that alone before sticking your hands in there. Plus, it only works if the tubes are installed, if you’re testing something with the tubes pulled, those caps will hold a charge for quite a while.
I have a Jet City JCA20H 20w 2xEL84 head. It doesn't have the nifty test point on the pcb. I saw a video here that showed how to bias it with a multimeter and I'd just like to verify the procedure before I make any adjustments. They suggest to check the plate voltage which is supposed to be around 350VDC (mine was 370VDC), then check the milliAmperes at each tube and plug those numbers into the following equation: 11.5watts x (600 / [PlateVDC]) = X [milliAmperes].
I think it depends on power transformer current capacity. With most amps I agree with you but take a fender princeton reverb amp with 2x6v6 and 4x12ax7 tubes feed from a 325VAC/70mA transformer with just 2A of filament current. It is taxed really hard, and will B+ will drop when biased hot. The 60mA for both tubes suggested by fender is with screen current also. Eurotubes has a video that shows that a test point reading of 91mV = 78mA plate current, which gives ~12- 13 mA screen.
I just had a Blues DeVille come in with major blow out damage on the board, 5 resistors, a couple of caps, and a chunk blown out of the board. The ONLY remedy is to cut out the bad part of the board and jumper everything. There is so much carbon tracking to ground the only other option is a new board, or new amp. If only you knew how little it costs to make on of these!LOL They still sound good. They are just hard to repair when things go wrong, and hard to modify without making a mess.
Hey Rob I really appreciated the video as I just bought a Blues Deluxe and it looks like the tubes are in same configuration. I have a lot of noise coming from the middle 12AX7, do I need to bias them as well as the 5U's if so is there are similar reference point and and adjustable potentiometer for the other side? Really appreciate the video, going to save me some money. Oh yah the noise goes away when I put pressure on the tube so maybe a quick solder is all that's needed.
great video.. WIth 485V plate (schematic) a value of 74mV (2 x 37mA) is a good medium warm bias (60% of max dissipation). The hot rod deluxe shows 431V plate and Fender recommends 60mA (30mA pr tube). That is cold for a set of large 6l6GC (30watt) tubes (less than 50%), at those voltages. With that amp you could go up to 84mV (2 x 42mA) for 60% dissipation. Even 90mV (2 x 45 mA) is not that bad. Just watch the plate voltage, my guess is that with the small PT it will drop when biasing hot.
@TubeDepotTV Thanks man. I just got JJ 6l6gc's and a tung sol 12ax7 for the V1 spot and two electro harmonix for the V2 and V3 preamps. Sounds great even without biasing it yet. Which leads me to my next question: I have an analog multimeter, any idea what setting it should be on? AC or DC? 500, 250, 50V?
Hi Fantastic video I plan to change my tubes watching this video as I have a hot rod deville. Last time I played the sound was getting fuzzy and losing power. Do you suggest any different tubes to the ones originally in the deville? another question. How do I know if the pre amp tubes need changing also? Im I correct in saying you changed the power tubes only in this video? is it the same method for pre amp tubes? Thanks. sorry for long message Cheers
Awesome video, just what I was looking for. Recently picked up one of these babies used. It played fine for a day or so then started doing some heavy volume fluctuating. The jewel light also fluctuated but not always in synch with the volume trouble. I popped the back off and checked the connections as Rob did in the video and they looked solid. It's my first tube amp and don't want to assume anything. Would a good first step be to pick up some new power tubes and pop them in?
when you said "there's a newer model", i suppose you were talking about the hotrod deville 3 ? as far as gettin new tubes, i'm gonna check out your catalogue see if there's any special custom sets for the 212 deville.. Thx once again for you answers and kindness.
Hey there thank you for your speedy response. so I seem to have found out the source of the issue, and I'd thought I'd share what I found. The speaker jack was plugged into the ext. speaker output on the chassis. someone must have plugged it back in incorrectly. does that sound like that would cause that kind of volume drop?
Thanks Rob for the info. Can you suggest what practical brand of KT88 tube good for this dyna mk3 in terms of quality but not much expensive like the three choices below from your TubeDepot: 1. Sovtek 2. Electro-Harmonix 3. JJ/Tesla so what about these 3 NOS respective cathode currents then? Is 70mA still safe or they are just between 45mA - 60mA?
Nice vid, never had seen all this biasing thing ......Btw, I also have a Fender Deville with Sovtek tubes but one of the preamp's is microphonic so I'm thinking of buying new ones. Which preamp tubes would you recommend for this amp? Thanks
Hi Rob, Like the video. Good solid and easy to follow. I have just changed to TAD 6L6 tubes and during biasing could not get less than 61mV at the bias test point (highest voltage pot would go was -60V, which gave me 61mV at the bias test point). I therefore backed off the pot voltage until I got 70mV as the bias voltage. Is there large tolerances between amps, or should they all be able to get 60mV without having the pot at max counterclockwise Regards, Allan
Good video, nice guitar playing ! I just replaced all the tubes on my brothers Deville, looking at the back of the amp, the left power tube looks like it never comes on, the amp still plays and seems strong. Could this be the solder connection you were talking about, or else what may be causing this ? Thanks !
Thank you so much for your video mate! Can you please tell me why did you need to read negative voltage before you read positive also do you only bias when changing power amp tubes or also when changing preamp tubes! Many thanx
Wow! You made it look easy. I have a question. I have a Hot Rod Deluxe. I put new JJ power tubes in and the started rattling shortly after. The guy at JJ said it's because I have a combo and the amp vibration is the cause. What do you think? Also what replacement tubes do you recommend? I play rock, blues, country.
@TubeDepotTV Ok Rob but tell me somenthing The TAD web says: 'The bottle is made from very thick glass and my sample of four were consistently straight and internally well aligned. I have no worries at running them at 450 volts and above average current. The plate construction is more conventional than a JJ but TAD has added cooling fins to both halves of the plate structure. This helps get rid of the excess heat when you run them outside of the standard 6V6 envelope.'
Hi Rob! Thanks for the great manual for replacing the power tubes on the DeVille. I've the same amp (only difference: I've got the 4x10" version) and recently I replaced my 6L6 tubes. Now I've got a question: My other amp is a Fender Twin Reverb Reissue from 1992 and would ask you for a replacement manual for the power tubes there. Same as on the Deville? As far as I know the Twin has also a BIAS knob. What are the measure data for the BIAS there?
Very informative and to the point. Thanks for sharing.. Mighty fine guitar playing as well. That's how my amp used to sound. I repaired a cracked solder joint at the "foot switch" connector, but now I find there's something not right with the far right, small(pre-amp) tube. A friend tested my tubes by removing them, then stuck new tubes in thew sockets(1 by 1). That's when I noticed he wasn't quite somber enough to be doing this test. He either bent the pins and/or caused damage at the connection. I realized this when it popped and cut in and out as I barely wiggled the the tube. Are the tube pins worth messing with till they fit again(If that's the only damage) or should I just replace them with new tubes?
Hello Rob. I'm an owner of the Hot Rod Deluxe ( 12 inch speaker ) and the amp is the smaller brother of the Deville but looks prett much the same inside. I'm living in Holland so our current is 230V AC unlike the 110V in the states. Does that make any difference in biasing the power tubes? I read somewhere that you recommend 70mv for a Hot Rod Deluxe. Is this a safe value for my amp. I appreciate it that you took the time to explain this ! Thanks
@TubeDepotTV Thanks for the quick response! Is it normal for the bias to oscillate a bit over time? If i let the amp warm up and then set the bias to, for example, 65mV, it will eventually drop to 61 after a couple of minutes. I thought it was normal for it to rise a bit due to the amp getting warmer, not to drop! Right now the amp is on and i'm checking the bias every couple of minutes, when i first turned it on it seemed to be around 65mV, then dropped to a stable(ish) 60mV. Is it normal?
i have a Hot Rod Deluxe. I picked it up used, and swapped out all the tubes today. 2 brand new mesa boogie 6l6 for power, and 2 groove tube 12ax7-r for the pre. Since it's used, and i don't have the manual, any advice about what to bias to? Close to 60 like the deville? Already gave the new tubes a quick test, sounds much better.
Nice demo! I have the same amp and it has been great aside from one issue. Is the volume knob on your amp extremely sensitive? There seems to just be a fraction of a degree between inaudible and glass-shattering loud with mine. Is there an easy way to either adjust this or perhaps replace some hardware to distribute and voltages a bit more evenly? Thanks!
Hello! I am new with tube amps and I am planning to buy one. The amp I am planning to buy also has 2 power tubes. Is this method you showed is alwasy the same? 1. Turn the tripmot full counterclockwise while in standby mode 2. Turn the amp on (switch it out of bypass) and set the voltage to the desired amount while touching the sowder spot of the powertube? What do you recommend when replacing with different tubes? Does the safe voltage remain the same? Thank for you reply in advence!
@TubeDepotTV Looks like one of the preamp tubes was a little loose! Thanks for all the help, do you guys ship to Canada and if so, can you ship via USPS?
Is there any chance of salvaging a pulled PCB trace leading to the power tube socket? I'm fairly confident with soldering, and I have 18 gauge solid core wire I've used to replace bad traces in guitar pedals. I think my concern is long-term sustainability. It seems like once the solder mask is pulled, the copper trace continues to deteriorate pull off the board. I assume the only alternative would be a lot of work around hand wiring the traces off those finicky ribbon connectors.
Been using tube amps for 25 yrs and never truly understood how they work just loved the sound. Your series on tubes is second to none! Thank you so much for posting this and sharing your knowledge, it is appreciated. Looking forward to more.
This video was so helpful. Replaced the tubes in my Fender Blues Deluxe reissue. Worked great! Thank you!
Same test point on the blues deluxe? Service manual for deluxe is different.
MAds
I have a mk2 deville ( made in mexico) I fitted a fromel supreme kit ,and changed all the valve sockets to gold ceramic .I usually set the bias a 68 mv ,I also recently changed the first ax12 to a at12 ,this has made the volume much more controllable
Best explanation ever... Happened to be the first video I clicked on, what luck. You have just saved me hours of my life! Thanks for that!
Excellent instruction. Just got a HRDV 410 and walked through the steps. Fantastic result. Beautiful cleans for days and very silent even with single coils. Thanks very much.
Great info and sick blues at the end. Love it
Great video! Very helpful and informative. I've had my Deville for probably 10 years and I was never 100% happy with the gain/overdrive channel. It sounded.......raspy.....not smooth at all.
I installed a Fromel kit, which made things better....but still....something wasn't quite right.
I had the amp serviced/biased/etc. Again.....better, but not quite 'there'.
So I found your video and did as you suggested. The bias was set at 58-59, and the blue trimmer was epoxied in place.
I powered-off and carefully trimmed the epoxy. I set the bias to 68 (the alleged 'sweet spot'), let it warm-up and took it for a spin.
Much better! I was more satisfied with the gain....definitely an improvement.
I also thought the clean channel had improved as well.....I could hear a difference.
I kicked the bias up to 70 and I'm happy with it. Looking forward to next band rehearsal.
Rob, was looking for a simple video for biasing a Vibrolux and came upon this one. Since I purchase tubes like I'm sure many below from you all, I was happy to find this video. Very well presented, clear to understand and a great help for dummies like myself. Thank you.
Most excellent straight forward biasing video ever.
G'day Rob, I hope you've been well in this time of crisis. I'm 11 years or more late on this, but I guess it's better late than never. Amongst most of the Biasing for the Hot Rod Deluxe I've seen, I decided to follow yours because it is the most clear (visually plus the audio & explanations) I've just done my Hot Rod today .. with 101% confidence thanks to you. Just one thing which I thought is super important, for those non-techo's like me. .... that's the detailed settings of the multimeter. I had to go over your video a few times to be sure. Where you set the multimeter to "Volts" to take the reading of the plate behind the Bias adjust knob, but mentioned very little about changing the multimeter to mV when setting the actual Bias while at the same time looking at the mV readings. I was lucky I saw the different settings showing on the video for your multimeter and so followed. In my case every detail of the procedure is important. Hope this will help you help us (non-techos) for future video releases. Stay well and all the best.
ru
Good.
Point taken.
I just bought a fender hotrod deville that had a very loud microphonic howl, seemed to be the first valve in line of the 3 small ones, was going to buy a complete new set, but then I just swapped the first to around absolutely perfect now.
A good hint to try first.
Great video! Kudos for mentioning the connections.
hey, yes, all the solder connections are fine. I just thought it was strange that i couldn't get it under 73mV but i made a call to the store and they said it's perfectly normal. They offered me to return them in if i wanted, so they could give me another pairbut as you said 73mV is a nice value. Great vid by the way! nicely explained for electronica noobs (like me)
Great video, well done! I own a HotRodDeluxe and this thing is always frying tubes. I took it to a tech who claimed to have biased it correctly but two days later at a gig I only had one 6L6 working, glowing extremely bright amber, distorted badly on the clean channel (I only use the clean channel) until it died all together. This was back in '05. I have a tech friend install new tubes 'bout a year ago and bias it, and it distorted again. I bought new tubes and I'll use your vid to DIY. Thx
Thanks so much for making this video. Great explanation and instructions.
Excellent video production and clear instruction, thank you!
Hi. OK understood now, I'd got milliamps on my mind.
Got the right measurement now.
Thank you for all your help.
Brilliant.
wonderful presentation!!! breath of fresh air!!!!!!
got the new JJs in the mail today and checked em out by swapping one position at a time, swapped V3 nothing put the original in. tried V2 still nothing, tried V1 which I suspected and got a low volume fuzzy tone even on 12, so I put another one of the JJs in the V2 position and she jumped back to life with even more tone, put the last new one in just to complete the set and i figure ill hang on to the one good one for emergencies till i get a few spares, Thanks again for your help
Nice video man! Very informational and easy-to-follow 👍
Thanks for this awesome video! I just bought a deville and this video is a big help!
@TubeDepotTV i knew it was a legacy because of the bridge and the tremolo arm.... they´re just the best guitars for me, i have the legacy special model, and also have a deville amp... awesome combination... excelent tutorial i am about to do this to my amp, greets!
Thanks dude, great video, very well spoken and nicely put together!
I'm just about to change the tubes on my Blues Deville and I hope I goes as smoothly as your video!
That's some purty good playin at the end Rob!
excellent video and kudos for providing safety review . . . very important!
thank you for your wonderful comment.
@TubeDepotTV thanks a lot! I ended up settling at 70mV, messed with it back and for for a while and 70 just seemed to be a good middle ground where i got the best tone without killing my tubes
I don't know much about amps,I'd rather watch your playing.I like it,U teach?
Hi! great tutorial! I have a question, I have a old hot rod deluxe made in USA and I would like to know what are the valves you recomend me. I would like to change all of them. Thanks from Spain!
Thank you I found the problem it needs new tubes 1 overloaded due to the lack of electricity. I'll retube it & be careful of what is tied into the outlet before I plug it in. Thank you for your videos on tube amps & a walk though of my & many other peoples post.
Yeah, that makes some sense.
After I watched your vid, I perused other utube biasing vids, and all the techs were touching the tubes and viewers were commenting the same thing I said to you (I guess I'm not as alone as I thought in my old thinking). It would be so cool if you could demystify this old wives tale by doing an unbiased test (no pun intended) using two sets of matched power tubes, one totally filthy, and one spotless.
thanks, I also tapped the reverb tank and could hear the springs through the speakers so thats working ok, it was bad timing too cause my Wampler tweed 57 pedal had just came in the mail and I was itching to try er out. Still in Awe over how many tools and tube accessories you have on the tubedepot store, wouldnt mind getting one of the 18 Watt british amp Kit sometime in the future.
Awesome. One of the best vids on youtube.
Very Good Explanation! Glad you mentioned safety. Too bad for the Test Point - the PCB should have a Tip Probe socket for holding the DMM's probe. To minimize the chance of getting an electrical shock (although not UL approved/tested) I wear the Black thicker Mechanics "Nitrile Gloves". Love 6L6 amps like the Deville (I have a Peavey ValveKing 2x 6L6). A dab of Nail Polish or RTV/Silicone keeps the pot from moving after being set.
Oh ok! Thank you for the quick reply! Your video was very informative and helpful!
Excellent. Thank you for your time and incredibly helpful reply. I really appreciate it.
thanks for the help I lowered my bias as low as it can go 30. now its playable beyond 1
Great vid, clear and to the point. thanks for that
thanks rob, and thanks for posting! great vid!
Holy shit thank God for this video!!! So well explained!!🙌🏻🙌🏻🙌🏻
Great video. Cool guitar playing too. I thought these amps had 2 speakers.
Very nice video and it's just not right that your top technician can play the guitar like that. Very impressive.
I so wanted to be a guitar god ... but sadly my playing has always been well below the "god" rating. Therefore, I had to find a real job ... enter electronics tech.
Brilliant vid and pickin !
The lad just picked up a HR Deluxe ii ....fantastic sound except the power tubes are noisy on some low notes. Gonna try some damper rings but if that doesn't work then may be putting your instructions to use soon with a pair of new tubes.
Really good. Keep on rockin.....
Hi Rob, Tube Depot, Just a little FYI, the ribbon connectors on the Deville can come loose and this will cause issues with the amp and performance of. El Paso Tube amps on TH-cam did a video about this problem, worth a view. Discharge filter caps first when working on amps, use only one hand when hooking up meter. Also see Uncle Doug on YT, very knowledgeable. Take care, C.
I played a gig last night with some band and the other guitar player's amp died on the gig...it was a Hughes and Kettner though....he came back 20 minutes later from his house with a Deville!
this was very informative, cleared up a few things for me.
cheers mate much appreciated
p.s guitar playing at the end was killer, should upload a video with just you jammin
At 1:23 you say to not touch anything without first discharging the amp. How is this done? Will simply turning it off and unplugging your amp discharge it after a period of time?
Mike Lowrey Well, probably, after a month..
I'm tempted to say "if you have to ask, don't do it." - Not to be snarky, but because it's actually dangerous.
A power resistor is used to discharge the power supply filter caps.
There's a lot of videos about it.
If in doubt, take it to your tech.
I made a wand out of a cheap screwdriver, alligator clip and a 1k resistor. Alligator clip lead is soldered to the resistor, resistor to the Clip the alligator clip to the chassis, touch the end of the screwdriver to the positive end of one of the filter caps. That will usually discharge most caps in less than 10 seconds.
They will discharge after turning the amp off while the cathodes are still hot enough to emit electrons. But don’t rely on that alone before sticking your hands in there. Plus, it only works if the tubes are installed, if you’re testing something with the tubes pulled, those caps will hold a charge for quite a while.
I have a Jet City JCA20H 20w 2xEL84 head. It doesn't have the nifty test point on the pcb. I saw a video here that showed how to bias it with a multimeter and I'd just like to verify the procedure before I make any adjustments. They suggest to check the plate voltage which is supposed to be around 350VDC (mine was 370VDC), then check the milliAmperes at each tube and plug those numbers into the following equation: 11.5watts x (600 / [PlateVDC]) = X [milliAmperes].
Great Video Rob!
Fantastic presentation!
Thanks ...
I think it depends on power transformer current capacity. With most amps I agree with you but take a fender princeton reverb amp with 2x6v6 and 4x12ax7 tubes feed from a 325VAC/70mA transformer with just 2A of filament current. It is taxed really hard, and will B+ will drop when biased hot.
The 60mA for both tubes suggested by fender is with screen current also. Eurotubes has a video that shows that a test point reading of 91mV = 78mA plate current, which gives ~12- 13 mA screen.
I just had a Blues DeVille come in with major blow out damage on the board, 5 resistors, a couple of caps, and a chunk blown out of the board. The ONLY remedy is to cut out the bad part of the board and jumper everything. There is so much carbon tracking to ground the only other option is a new board, or new amp. If only you knew how little it costs to make on of these!LOL They still sound good. They are just hard to repair when things go wrong, and hard to modify without making a mess.
i got a hold of some tad 6l6gc-str, they sound fantastic! biased at 75mv excellent tone.
Thanks!!!! Right on spec , just did mine....sounds great!!!!!
Hey Rob I really appreciated the video as I just bought a Blues Deluxe and it looks like the tubes are in same configuration. I have a lot of noise coming from the middle 12AX7, do I need to bias them as well as the 5U's if so is there are similar reference point and and adjustable potentiometer for the other side? Really appreciate the video, going to save me some money. Oh yah the noise goes away when I put pressure on the tube so maybe a quick solder is all that's needed.
great video.. WIth 485V plate (schematic) a value of 74mV (2 x 37mA) is a good medium warm bias (60% of max dissipation). The hot rod deluxe shows 431V plate and Fender recommends 60mA (30mA pr tube). That is cold for a set of large 6l6GC (30watt) tubes (less than 50%), at those voltages. With that amp you could go up to 84mV (2 x 42mA) for 60% dissipation. Even 90mV (2 x 45 mA) is not that bad. Just watch the plate voltage, my guess is that with the small PT it will drop when biasing hot.
@TubeDepotTV Thanks man. I just got JJ 6l6gc's and a tung sol 12ax7 for the V1 spot and two electro harmonix for the V2 and V3 preamps. Sounds great even without biasing it yet. Which leads me to my next question: I have an analog multimeter, any idea what setting it should be on? AC or DC? 500, 250, 50V?
Hi Fantastic video
I plan to change my tubes watching this video as I have a hot rod deville.
Last time I played the sound was getting fuzzy and losing power.
Do you suggest any different tubes to the ones originally in the deville?
another question. How do I know if the pre amp tubes need changing also?
Im I correct in saying you changed the power tubes only in this video?
is it the same method for pre amp tubes?
Thanks. sorry for long message
Cheers
extremely helpful video. thank you so much.
Awesome video, just what I was looking for. Recently picked up one of these babies used. It played fine for a day or so then started doing some heavy volume fluctuating. The jewel light also fluctuated but not always in synch with the volume trouble. I popped the back off and checked the connections as Rob did in the video and they looked solid. It's my first tube amp and don't want to assume anything. Would a good first step be to pick up some new power tubes and pop them in?
when you said "there's a newer model", i suppose you were talking about the hotrod deville 3 ? as far as gettin new tubes, i'm gonna check out your catalogue see if there's any special custom sets for the 212 deville.. Thx once again for you answers and kindness.
Thanks for sharing
Hey there thank you for your speedy response. so I seem to have found out the source of the issue, and I'd thought I'd share what I found. The speaker jack was plugged into the ext. speaker output on the chassis. someone must have plugged it back in incorrectly. does that sound like that would cause that kind of volume drop?
ok thanks for your comment. all the best mate.
Thanks Rob for the info.
Can you suggest what practical brand of KT88 tube good for this dyna mk3 in terms of quality but not much expensive like the three choices below from your TubeDepot:
1. Sovtek
2. Electro-Harmonix
3. JJ/Tesla
so what about these 3 NOS respective cathode currents then?
Is 70mA still safe or they are just between 45mA - 60mA?
Nice vid, never had seen all this biasing thing ......Btw, I also have a Fender Deville with Sovtek tubes but one of the preamp's is microphonic so I'm thinking of buying new ones. Which preamp tubes would you recommend for this amp? Thanks
Hi Rob, Like the video. Good solid and easy to follow. I have just changed to TAD 6L6 tubes and during biasing could not get less than 61mV at the bias test point (highest voltage pot would go was -60V, which gave me 61mV at the bias test point). I therefore backed off the pot voltage until I got 70mV as the bias voltage. Is there large tolerances between amps, or should they all be able to get 60mV without having the pot at max counterclockwise
Regards,
Allan
Good video, nice guitar playing !
I just replaced all the tubes on my brothers Deville, looking at the back of the amp, the left power tube looks like it never comes on, the amp still plays and seems strong.
Could this be the solder connection you were talking about, or else what may be causing this ?
Thanks !
Thank you so much for your video mate! Can you please tell me why did you need to read negative voltage before you read positive also do you only bias when changing power amp tubes or also when changing preamp tubes! Many thanx
Wow! You made it look easy.
I have a question. I have a Hot Rod Deluxe. I put new JJ power tubes in and the started rattling shortly after. The guy at JJ said it's because I have a combo and the amp vibration is the cause. What do you think? Also what replacement tubes do you recommend? I play rock, blues, country.
@TubeDepotTV
Ok Rob but tell me somenthing
The TAD web says: 'The bottle is made from very thick glass and my sample of four were consistently straight and internally well aligned. I have no worries at running them at 450 volts and above average current. The plate construction is more conventional than a JJ but TAD has added cooling fins to both halves of the plate structure. This helps get rid of the excess heat when you run them outside of the standard 6V6 envelope.'
Thanks for the reply TubeDepotTV.
Yep. These have a test point and a potentiometer to adjust it. 👍
Excellent instruction. Can this similar bias adjustment be done on the Fender 410 blues Deville reissue, 2005 model?
Great Video! Is there a Marshall JTM 45 video like this? That would be cool!
it's Bob from Brookwood Leather : )
Otaypanky is my alter ego ~
Have a great 2013
Your videos are so cool
Thanks for the reply and help David or guys at tube depot!!
Very good video. How do you bias an amp that doesn't have the test point, say like a 64 blackface with an AB763 circuit?
very informative video. i enjoy it, and u play great too.
keep posting some good stuff. :)
Great video man.
Hi.
Why is the power tube guard missing.
Good info by the way.
Hi Rob! Thanks for the great manual for replacing the power tubes on the DeVille. I've the same amp (only difference: I've got the 4x10" version) and recently I replaced my 6L6 tubes.
Now I've got a question: My other amp is a Fender Twin Reverb Reissue from 1992 and would ask you for a replacement manual for the power tubes there. Same as on the Deville? As far as I know the Twin has also a BIAS knob. What are the measure data for the BIAS there?
Very informative and to the point. Thanks for sharing.. Mighty fine guitar playing as well. That's how my amp used to sound. I repaired a cracked solder joint at the "foot switch" connector, but now I find there's something not right with the far right, small(pre-amp) tube. A friend tested my tubes by removing them, then stuck new tubes in thew sockets(1 by 1). That's when I noticed he wasn't quite somber enough to be doing this test. He either bent the pins and/or caused damage at the connection.
I realized this when it popped and cut in and out as I barely wiggled the the tube. Are the tube pins worth messing with till they fit again(If that's the only damage) or should I just replace them with new tubes?
Hello Rob. I'm an owner of the Hot Rod Deluxe ( 12 inch speaker ) and the amp is the smaller brother of the Deville but looks prett much the same inside. I'm living in Holland so our current is 230V AC unlike the 110V in the states. Does that make any difference in biasing the power tubes? I read somewhere that you recommend 70mv for a Hot Rod Deluxe. Is this a safe value for my amp. I appreciate it that you took the time to explain this ! Thanks
@TubeDepotTV Thanks for the quick response! Is it normal for the bias to oscillate a bit over time? If i let the amp warm up and then set the bias to, for example, 65mV, it will eventually drop to 61 after a couple of minutes. I thought it was normal for it to rise a bit due to the amp getting warmer, not to drop! Right now the amp is on and i'm checking the bias every couple of minutes, when i first turned it on it seemed to be around 65mV, then dropped to a stable(ish) 60mV. Is it normal?
Great vid, thanks.
i have a Hot Rod Deluxe. I picked it up used, and swapped out all the tubes today. 2 brand new mesa boogie 6l6 for power, and 2 groove tube 12ax7-r for the pre. Since it's used, and i don't have the manual, any advice about what to bias to? Close to 60 like the deville? Already gave the new tubes a quick test, sounds much better.
Hey, excellent video! Very informative. Would the Hot Rod Deluxe be the same way, but set at 40v instead of 60v? or would it also be 60v?
Awesome! thanks so much! anything different for a Hot rod deluxe?
Thanks man!!! Does this go the same for the 4x10 model?
Great video. Should the bias level be set differently for different brands of tubes or is 60 generally a safe bet?
Nice demo! I have the same amp and it has been great aside from one issue. Is the volume knob on your amp extremely sensitive? There seems to just be a fraction of a degree between inaudible and glass-shattering loud with mine. Is there an easy way to either adjust this or perhaps replace some hardware to distribute and voltages a bit more evenly? Thanks!
Hello!
I am new with tube amps and I am planning to buy one.
The amp I am planning to buy also has 2 power tubes.
Is this method you showed is alwasy the same?
1. Turn the tripmot full counterclockwise while in standby mode
2. Turn the amp on (switch it out of bypass) and set the voltage to the desired amount while touching the sowder spot of the powertube?
What do you recommend when replacing with different tubes? Does the safe voltage remain the same?
Thank for you reply in advence!
nicely done video
@TubeDepotTV Looks like one of the preamp tubes was a little loose! Thanks for all the help, do you guys ship to Canada and if so, can you ship via USPS?
Great video - Do you know if this is the same in the Fender Blues Deluxe?
Thanks for your help.It seems that I had a bad tube. You'd think you could trust brand new tubes, but not always I guess. Thanks again.
Is there any chance of salvaging a pulled PCB trace leading to the power tube socket? I'm fairly confident with soldering, and I have 18 gauge solid core wire I've used to replace bad traces in guitar pedals. I think my concern is long-term sustainability. It seems like once the solder mask is pulled, the copper trace continues to deteriorate pull off the board. I assume the only alternative would be a lot of work around hand wiring the traces off those finicky ribbon connectors.
Thank you for your answer,i'll contact Soldano soon!
Great video!!