How To Bias a Deville Amplifier

[@gvb54]

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.

[@antwannn111]

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!

[@ArtDonna84]

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.

[@rockbandgamer]

This video was so helpful. Replaced the tubes in my Fender Blues Deluxe reissue. Worked great! Thank you!

[@bobandy3197]

Same test point on the blues deluxe? Service manual for deluxe is different.

[@yusufandongvlogs6954]

MAds

[@bazjones7349]

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

[@rudolphgaroa1960]

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

[@mjs28c]

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.

[@VintageRandom]

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.

[@01MrGibson]

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.

[@hhscadets0925]

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?

[@xenod1066]

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.

[@bart99gt]

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.

[@GameLevelEditor]

Most excellent straight forward biasing video ever.

[@wildparlor5456]

Great info and sick blues at the end. Love it

[@harrykarmona]

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!

[@moogmanXanders]

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.

[@moogmanXanders]

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

[@robertnewman2864]

Excellent instruction. Can this similar bias adjustment be done on the Fender 410 blues Deville reissue, 2005 model?

[@WillCorg]

I bought my DeVille 2/12 in 1996 and I've never adjusted the bias level... the original Fender tubes burnt out in 1998 and I replaced them with a set of tubes from a guy I found in the Nickel Ads in Portland Or. They've never gone bad and still work to this day! I'd be interested to see what the bias level is set to?

[@MiloMeskensOfficial]

and wich multimeter did you use?

[@almpinho]

Hi, fantastic video! I have this same amp and at now I know do the bias adjustment in my HRD 2x12". But I would like to know which is the plate voltage of this HRD for calculate the 100% of bias value and 70% also. I thing this value varies from each same amp and I would like to know how measure this value. Please, if it's possible to you, make a video explaining how to measure the HRD 2x12" plate voltage value!!! Thanks

[@4Dcruz]

@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

[@MiloMeskensOfficial]

If I have 4 6L6 (100w) will I still have to bias it to 60 mV?

[@zoomer51]

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.

[@RoxxHoffner]

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?

[@glennkubik3774]

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.

[@bill.clifford.59]

Thanks for this awesome video! I just bought a deville and this video is a big help!

[@real_fjcalabrese]

Great video! Kudos for mentioning the connections.

[@cassvirgillo3395]

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 KZbin 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.

[@dstrats]

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

[@TubeDepotTV]

Nik, installing EL34 tubes in the Hot Rod DeVille would require modifying the amp. If you want a close EL34 sound, I recommend trying the JJ 6L6 as these have a very compressed, low vacuum sound ... very similar to an EL34.

[@MadSpectro7]

I would think that EL34s would merely require re-biasing. All octal-pin tubes use the same plug and socket.

[@Jonw8222]

Shoes EL34's draw more current which means they need a sturdier OT (more ma headroom in the output transformer) and higher screen resistor values, and sometimes also different bias resistors depending on if they can be biased with the trim pot (if the value is in the range of the pot). Sometimes you can get away with just swapping them but common screen resistors for 6L6 is 470ohm resistor and EL34's for better with 1K or 1.5K resistors. You can see in this video that even at max range, this bias pot didn't have much throw and would be hard to run EL34's in.

[@alvagoldbook2]

Shoes Both the power transformer and output transformer would have to be replaced to put EL34's in this amp, along with changing the screen grid resistors as well as changing some of the wiring on the tube sockets, which isn't very easy since their PCBs.

[@MitchelYoung]

+Alva Goldbook one of my tube amps (and only one out the 30+ I own) a Carvin MTS 3212 has a switch to select between using EL-34 or 6L6GC tubes. it says in the owners manual that it has different taps on the transformers and different resistors and different heater loads. Either way the amp has some great tones. This amp also has a switch that literally shuts off two of the power tubes to drop from 100w to 50w. but that's another story. you will almost certainly damage the amp if you use the EL-34 instead of the 6L6 where specified, but what would happen if you use a 6v6, the JJ seams to have very similar specs, . Could I get my Blues Deville 410 to break up at much more usable volumes? Just wondering?

[@alvagoldbook2]

Mitchel Young Yes, you can use 6V6s as a drop in replacement for 6L6s in a Fender Blues Deville, but you would have to rebias the amp. It may even require a modification of the bias supply circuit. I've heard of many people doing this with these amps, but do NOT use some vintage NOS 6v6 tubes, as they would most certainly get fried, and possibly damage your amp. Rather, you should stick with the more sturdy modern production JJ 6v6s which are designed to handle such abuse. Another way to tame the volume of the amp is to use an attenduator. Those can be pricey. One trick that worked pretty well for me was plugging into the 2nd input jack and removing 2 of the 10 inch speakers from the amp. I'm thinking I might just put a new baffle in my Hot Rod Deville 410 and replace it with 2 12 inch speakers. The fewer the speakers, the less the volume. You'd be surprised by just how effective this little trick is. Just make sure you have your remaining speakers wired up correctly.

[@jeremyberg9693]

wonderful presentation!!! breath of fresh air!!!!!!

[@jamessanscrainte9533]

Thanks so much for making this video. Great explanation and instructions.

[@Themostrelentlessronin]

Great vid just subscribed glad to find someone who can explain step by step for a D.I.Y. saved me money. I have the blues deluxe reissue is this similar process as well?

[@rockventures]

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.

[@jasoncobb7427]

At 4:14 isn't the bias test point the one on the corner?

[@Sandelb]

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?

[@AGTR98]

Can someone tell me what the 3:28 step is for? So you measure the voltage and adjust it to the most negative using the same pot thats used when checking the tube test ? What i want to know is if you basically just roll it back and then clockwise

[@AGTR98]

Is it because it was on stand by? Does the function of the pot change with the stand by toggle?

[@bostonmassappeal]

Awesome. One of the best vids on youtube.

[@PeterDad60]

I used this most excellent of all tutorial's in 2015 for biasing my new Fender Dot Rod Deville III 410. I deliberately set the Ma to only 57-59 Ma to prolong tube life. Now I have been wondering to my self if this is too cold and did I sacrifice tone. I can not get power tube break up at any volume and when it's at full volume I get that "ice pick" pain in my ears it's so loud. I think I shall re-bias to the 60 Ma and maybe change V1 to the 12AT7 which has 60% as much gain as the 12AX7 which has 100%. The available Pre Amp tubes have these gain factors: 12AX7 100% 5751 70% 12AXT7 60% 12AY7 45% 12AV7 41% 12AU7 19% Changing tubes is not difficult so I may even set the bias as high as 70 Ma or 80 Ma just as rob mentioned. If the amp then sounds warmer to my ears it will be worth the cost of purchasing new tubes sooner. After all I did not purchase the amp to save money but rather to enjoy the tone of a fine amplifier. He, he, as usual I outsmarted myself with the too cold re-bias from the factory settings of 60 Ma. Live and Learn! Thanks again Rob for your video, for re-biasing/bias of a Fender Deville it's the best one on You-Tube!

[@PeterDad60]

I tried 2 different 12AT7's and at volume over 4 1/2 the amp made a strange noise. I have decided my amp only want's 12AX7's.

[@Stratocooler]

Hi Nick, if you can tell me why it is an important first step, set the power - 60 volts, and whether it is necessary to measure bias in milli volts or in milli amps, and what is the difference in these measurements. Best Regards

[@Myamptech]

Stratocooler - setting the bias control voltage to its most negative level insures the tubes aren't installed with a bias control voltage that could cause tube damage. the negative 60V is the starting point.

[@silasfatchett5693]

'Biasing' is the procedure which sets the 'plate dissipation' of the tubes. This is determined by the plate voltage multiplied by the amount of current flowing in the tubes. The pot adjusts the negative bias voltage on the tubes' control grids which determines the current in the tubes and therefore the plate dissipation. The voltage at the pot is the actual negative bias voltage, and setting it to -63V (or as high as it will go) means that the current in the tubes is at its minimum and can be adjusted from there up to its recommended value. In this amp, (and some others) there is a 1 Ohm resistor between the cathode(s) and ground through which plate current must flow. The voltage across this resistor is measured at the test point, and the number of milliVolts across the one ohm resistor is the same as the number of milliAmps flowing through it. (From Ohm's law: current = volts / resistance, I = V/R, so (e.g.) 30mV / 1 = 30mA.)

[@OhHeyFixItGuy]

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.

[@JeffDumps]

Excellent video production and clear instruction, thank you!

[@al94551]

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

[@MattsArtStuff]

Question? Is it normal to hear a buzzing sound coming from the upper PCB board on the Fender 410 Deville? It sounds as though it might be coming from one of the large grey capacitors. Thank You, Matt

[@salalexander5950]

Hi - the bias test point on my recently acquired (used) Hot Rod Deville 410 won't go past 30 mV even with the bias pot turned all the way clockwise. I have all the volumes down, power on and standby off, and 30 mV is the actual reading (I didn't divide by 2). I only have the tubes that came with the amp. Is there any explanation you can think of? Nice playing!

[@Wi66pro]

Hi, I have the same issue with my Hot Rod Deluxe. Not as low as your readings but the maximum reading I get is 59mV's. To get a setting so I'm not burning up my tubes I have to set it at 30mV's, which is about halfway. So far I haven't found out why my readings are a lot lower than Fender and others recommend.

[@salalexander5950]

I had a burned out 470 ohm resistor and probably bad power tubes. There are two 470 ohm resistors - one going to each power tube (I think coming off pin 3 - you can see the pin numbers if you look on the white plastic that the power tube plugs into, from inside where the ciruit boards are). I got some 1 watt 470 ohm resistors (xicon) from Mouser.com and replaced the tubes. Now I was able to bias my amp to 66mV. I found the answer to my own question in this article: www.maxxplay.us/img/hrdx/How%20to%20Bias%20&%20Biasing%20FAQ.pdf

[@Wi66pro]

Sal Alexander Thanks for the reply, much appreciated. I've changed my tubes, had same problem with previous pair also, so next step will be to check the resistors. Thanks again.

[@Myamptech]

Sal Alexander - You likely have an amp issue. There is likely an open component or poor solder connection. A qualified amp tech needs to look at your amp.

[@Myamptech]

Fender56 You likely have an amp issue. There is likely an open component or poor solder connection. A qualified amp tech needs to look at your amp.

[@andrewt248]

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].

[@01MrGibson]

Hi. OK understood now, I'd got milliamps on my mind. Got the right measurement now. Thank you for all your help. Brilliant.

[@Redpepper917]

Nice Video. I like the information. 1 Question; Volt Setting on the multimeter is DC Volts or AC Volts. ( I saw DC VOlts in this video but I believe Alternating signal is in the amp). Please clarify. Thanks.

[@silasfatchett5693]

The meter is set to measure DC milliVolts.

[@gaur1000]

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?

[@sixstringer82]

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

[@someguyonaguitar]

@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?

[@MylesJP]

Nice explanation. Will adjusting bias help with the over-sensitive volume issue of this amp? The "smaller tubes" (pre-amp tubes? Sorry, mechanical engineer ignorance!) are 12AX7 models and I know you previously suggested 12AU7 or 12AY7 tubes. Are those tubes different enough from the X7s to be worth investing in or is there a simple resistor a person could drop in to solve this issue? Thanks so much!

[@TubeDepotTV]

The Hot Rod DeVille is a 50W amp. And in loud applications that require a 50W amp, the DeVille works fantastic. However, in quieter applications (such as at home or church) where a 10W amp would be better suited, this amp is much too loud. As such, there is much internet discussion on making this amp quieter without loosing tone. You can try installing lower gain preamp tubes, or 6V6 power tubes, or a volume pedal in the effects loop, or a different volume control. All of these will reduce (or modify) the volume some, but you will still be left with a very loud 50W amp. I've found the most effective solution is to use an attenuator between the amp and the speakers and control the volume that way.

[@MrMisterLondon]

The over sensitive volume Aunt Jemima mentions might be to do with the ratings of the pots as that is something Fender addressed in the latest version (III) of the Deville family. Versions I & II used to leap from nothing to very loud when turning the pots between values 0-1. Thanks for the video by the way! Consider me subscribed

[@MitchelYoung]

+TubeDepot FYI I just put a GT 12at7 in the PI tube of my Deville 410 and the volume seams much more usable, since the lead channel is not to my taste I will try a 12au7 in V2 and possibly even V1, what do you think? If I tried some 6V6 what would I set the bias to? Can I just test to see if I like the tone by taking the tubes out of another 6V6 amp I have such as a Marshall DSL15H or Fender Deluxe Reverb 65ri? or should I buy new? The JJ 6v6 seems closest in specs to the 6L6 so should I just buy a matched set of these

[@brenfen]

Great video. Should the bias level be set differently for different brands of tubes or is 60 generally a safe bet?

[@billwilliams6338]

TUBEDEPOT When you're biasing the power tubes in an amplifier circuit how do you bias the compression of the power tubes the 1dB compression point of when the power tubes start to compression? because its say to bias tubes at a 30mA bias current per tube to be safe but how do you know when the tube is compressing? Most Power tubes 6L6,EL34 use a B+450vdc on the plates, if you increase the B+ to +600vdc would this increase the AC ripple but why would it increase the AC ripple? i would think it would decrease the AC ripple because more B+ voltage mean less current draw from the power tubes.

[@Cro55co]

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

[@erikolson2897]

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?

[@LeviSiccard]

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)

[@funkyjones]

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.

[@bahady30]

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

[@zoomer51]

first off thx for this tutorial, im planing to get a used 212 deville and that's exactly what i need to check it out in a basic way.. Just a question though since im no tech or whatsoever, you first checked the "general" voltage by putting the red pin close to the bias pot, is there any solder point there since we can't see from that cam angle ? thx in advance for your reply. Cheers from france

[@alvin10388]

thank you for the great videos as always.Sir i have question,I have hammond 291AEX 240 euro power transformer,but the primary has two black wires not like us version ,in this case when i connect to champ 5F1push pull pot.do i have make sure which is hot and return or i can connect any of these two leads switch and fuse?any help really do appreciate.

[@billyburke7621]

Thanks man!!! Does this go the same for the 4x10 model?

[@Barnekkid]

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?

[@brokenbones112]

Hi I opened my hotrod deluxe up and its got a pair of sovotek 5881's in the power section, now it is 10 years old and i am not the origional owner, so keeping this in mind and the fact that i have no idea what im doing other than dont touch anything on the circuit board is there a different bias point for these tubes

[@1thess523]

I just got onw for my son 👍, can you clean the tone pots when you remove the backing plate?

[@mrgroise]

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.

[@justplanecrazy3d]

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 !

[@guitartec]

Great vid. but I gotta question.... I have been told by techs to never handle vac tubes because the dirt & oil from your fingers makes the tube run hotter and have a shorter life span. Iso alcohol is to be used to clean tubes if they are touched. Has this rule changed because of some techno improvement I don't know about?

[@stephentrageser]

I've got a Blues Deville, the reissue and I think the newer version of that, so the inside looks pretty much the same as the Deville here. I can see the bias pot and test point in the same position. The only thing I can't figure out for sure is whether or not it has the same recommend bias of 60mV. Is it? Where do they hide this information in the specs, or can you derive it from something else?

[@CARMINATISOUND]

Hi. Have a Deville 212. Cant get voltage on test point, but it is present on regulator... But even at max setting it only gets to around 54vdc. Local ac is around 109/110v. Any idéias?

[@brycethomas1138]

I have a DeVille as well and after watching this video i bought some new power tubes, changed them out and biased it myself, running a little hot cuz i like it break up a bit faster. . . But even after the power tube replacement my amp still sounds weak. Clean channel is fine, but channel 2, even with the drive ALL the way up doesn't sound like it used to. What does this mean? Do i need to change the pre-amp tubes to get that gnarly gain i used to get out of it? I've only had the amp for about 9 years. Which sounds like a long time, but i know people go even longer than that without changing the tubes. HELP ME BREH!!!

[@honkmagic]

so essentially what your doing is adjusting the voltage applied to the plate of each valve? similar to how you would bias the base voltage of a transistor?

[@Myamptech]

richard kerr - nope ... the voltage being adjusted is the control voltage which is applied to the control grid of the tube. The control grid of a tube is similar to the GATE lead of a FET. The plate of a tube is similar to the DRAIN lead of a FET. The cathode of a tube is similar to the SOURCE lead of a FET.

[@VinnieBlues1]

Hi...I'm a layman so I need to ask a question...do these parameters (approx. 60mV) work for any brand of power tube? The original ones that came on my Hot Rod are two 6L6GC GT and I want to exchange it for two JJ 6L6GC. So the ideal parameter is still about 60mV? Thank you so much

[@MrAnders1976]

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.

[@DjNorbax]

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

[@PeterDad60]

That's some purty good playin at the end Rob!

[@zeke5989]

What about biasing a Super Reverb reissue, it doesn't have the "bias test point"? Any tips on how to bias it would be much appreciated.

[@owlsonik37]

My circuit board where the power tubes connect is in the exact location as yours on my HRD and it’s a bit warped. Is that normal?

[@derzasekolahdidd]

does adjusting "bias voltage" mean the same as adjusting the voltage in "cathode bypass" resistor? And how can we manually figure out the idle voltage/ current?

[@MylesJP]

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!

[@j_music_8779]

Nice video man! Very informational and easy-to-follow 👍

[@gibstone23]

Hi Rob, firstly many thanks for this lesson, it was really helpful. I live in the UK so I have bought some GT-6L6-GE tubes from a local supplier. I have followed your instructions however even at the lowest setting I cannot get the Bias under 76. Could you suggest something I am doing wrong, it all looked pretty straight forward. Thanks Lee.

[@Myamptech]

Lee Gibson - sounds like you have some very hot running tubes. 76mV is not outside the limits of the tubes ... they will just run hot. The typical bias range is 60mV - 75mV.

[@cravelp1115]

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?

[@Yoshisakan]

Great video, thanks! Is the procedure similar for swapping out the 12ax7s? My deville has a noisy buzz in the gain channel. Ive tried multiple guitars and it nets the same result. Also when turning up both the presence and reverb past 50%, it makes this high pitched scream. I'm hoping one or both of these issues would be fixed after checking the solder points and swapping tubes.

[@deathbuster927]

It could be a microphonic tube. Fortunately preamp tubes don't need to be biased, you can just replace them without any further adjustment.

[@noahherne4626]

My amp is at 83 at the lowest bias setting. Its a 410 deville from 1997. What could be the problem?

[@violeman]

I am having a big issue & you seem to be "THE MAN" to ask!!! My Hot Rod DeVille will not switch down to clean channel (Always In Dirty Gain Channel). But when I power down the amp, It flashes Green for a split second... Do you know what could be causing this ? & Where I should be looking first & so on? I have been a Transtube Peavey Guy for 20 years now & just Inherited one of these fine Beauties !!! Thanks for the Tube Tips, Cause that would have been my next Question !!! Thanks 4 Sharing Bud!!! Rock On !!! DEv

[@Myamptech]

violeman - make sure the channel select switch on the top of the amp is not depressed or stuck in the down position. Clean as necessary.

[@DasJibbala]

violeman i've heard resistor 78/79 (the two next to the bias potentiometer shown in the video) can cause issues with channel selectors on hot rod amps, google that?

[@01MrGibson]

Hi. Why is the power tube guard missing. Good info by the way.

[@memoglz]

@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!

[@erikolson2897]

Hey Rob, thanks for the great video! I followed it very closely, and my volume is still very low when I tried to do a sound test. power tubes flicker blueish purple as I send a guitar signal to it. these amps are very loud as you know, but I have to turn up a lot to hear anything. I checked the voltages at the large grey caps and they appeared to be stable. I also replaced the 2 12ax7s closest to the inputs 1& 2 I was hoping you might have some thoughts on what might be going on here. thank you

[@joelkine]

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?

[@argentsilver928]

Any idea why my test point is showing 0 volts when I switch the amp on to set the bias?

[@jordanlcombs]

When biasing my hot rod deville, my voltage meter won't pick up any readings off of my bias test point. But it had a reading when turning the voltage up when the amp was on standby.

[@bromporke]

I followed all the directions with my Deville 2x12 and the DC mV reading was all the way up at 180mV at the testing point. I couldn't turn down the pot enough to get it down to 60mV... my bandmate tested his 4x10 Deville and got a normal reading.... what's wrong with mine that it would be running that hot?

[@thenoras]

I am not getting any voltage when I test it from the bias test point. From the bias pot I get -58V when all the way to the left. My tubes are old and i've been blowing fuses, so I assume one is bad. Would that cause it to not give me a voltage at the test point? I tried switching my 6L6's around with the same effect.

[@eightGhosts]

Any tips on biasing a Deluxe Reverb Reissue? I'd have no problem biasing an original, but the reissue is extremely confusing. Thanks!

[@ManfredRahn]

What are you doing with the knobs? You turn it all to "0" or clockwise to "12"??

[@jameslomax1271]

I have a acquired a fender De Ville 410 and we used it while having a practice it sounded a bit distorted, and after an hour we had a rest and whilst we were sat down it did a few pops. Have you any idea what could cause this please.

[@4Dcruz]

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.

[@elkien5225]

Great video - Do you know if this is the same in the Fender Blues Deluxe?

[@meldeer6253]

i have a Hot rod De Ville 4x10 lot-095270 some one unhooked the speaker wires do you know the wiring digram maby a picture thank you

[@AlessandroBertocz]

Isn't the bias supposed to be measured (as per fender's schematics) with all the knobs minus reverb set to 50% rotation, and the yellow channel selected? On my amp, rotating the knobs, especially the volume one, seem to make the reading vary a bit... PS.: Is -42V a good bias voltage (measured on the tube pin)? Plate is 460V, it's a 1997 USA made deville i just got, so i wanted to check if everything is still working properly