How To Bias EVH 5150 III Stealth 50 Watt & EVH 5150 III 100 Watt Stealth Head

[@hbkaplan131]

Great video. The day to day variants are due to line voltage changes. The power to high voltage is an unregulated power supply. Also, be sure the meter is on mVdc mode, Not Current Mode. And thanks for the nice comments.

[@cbphotovideotips]

Thanks Howard.

[@murdock8068]

Hey Howard. Does this apply to the lbx version of the stealth? I'm sure the values are different being lower wattage. Thank you

[@steveo4253]

Hi Howard, I just discovered your amplifier repair/mods website yesterday. A quick question, can I put 5881 tubes in the Stealth and what would the bias setting be at the test points ?

[@riccardo8676]

Maybe it would be better if they measured the plate voltage! Honestly I have adjusted to that to calibrate my bias and I have found that the bias measurement without plate voltage is quite inaccurate. Obviously due to the high voltage it is better for people to risk burning the amplifier rather than being electrocuted trying to open it.

[@ragingskeptic9753]

You are an amazing human being. My EVH 5150 III Stealth was flat and flubby. I had tried everything. I checked the bias, and it was set to 14.2 mV DC. I set it to 58 mV DC. It’s a whole new amp! Sharp, crisp, clear, and growls like a lion! THANK YOU!

[@cbphotovideotips]

Glad I could help

[@JJJJ-bg3yz]

@@cbphotovideotips so when biasing the hundred watt with the numbers be double from the ones you mentioned when you demonstrated the 50 W? Could you also confirm which setting on the multimeter we should be using? Thank you.

[@cardiacade]

Absolute legend. My amp was set to 20 and I wasn't happy with the sound. Now I've rebiased it it sounds great!

[@cbphotovideotips]

Great to hear!

[@cardiacade]

@@cbphotovideotips you've saved me so much frustration! Happy new year!

[@cbphotovideotips]

You are welcome, Happy New Year!@@cardiacade

[@jusbzyabz3319]

needed some new power tubes for my 50watt stealth, went with matched Sovtek 5881 6l6wgc. checked the bias on my old stock tubes & they were set at 35mV compared to the suggested 60mV from you & Howard. followed all these steps & the amp roar's now, it sounded like a blanket was covering the amp before but the tube swap & bias set at 60mV instantly brought it back to life, got wayyy more bite. I don't even need a boost in front of the amp now, thanks man

[@cbphotovideotips]

Awesome.

[@rosskrause3926]

Yep..my 50 watt Stealth head came with the Shuguang 6L6 power tubes and they barely lasted 3 hours before they started crackling really bad..but I happened to have a brand new pair of JJ's 6L6-GC's from Eurotubes that I had ordered prior to receiving my 50 watt Stealth head..it came to life big time after I swapped them in and checked the bias..this is an excellent vieo.

[@grumpyoldrockers1048]

Another great video Craig... Howard and I will be doing an experimental mod on the Blue channel for the Stealth 50w, once it's completed I'll post before/after video. Keep up the great work my friend.

[@cbphotovideotips]

Thanks

[@conrauxyann5398]

Excellent video ! However, I set my EVH 5150III 50 Stealth at 70mV, because at 58mV it sounds too much sterile IMHO. At 70mV it sounds open, warm (particularly on green & blue channels), but keeping typical tightness and crisp of its distortion, and slightly more headroom. Also, I changed the stock tubes (6L6GC Groove Tubes) for a pair of Tung-Sol 6L6GC-STR which are by far my favorite modern 6L6GC. Now my EVH is closer to my Dual Rectifier than before, with a great low end. As you said, let ears judge :-) ! And honestly I think at 70mV (35mA per tube), they will last long enough.

[@kirkkulhanjian9387]

I followed the instructions. Great video, but I’m not getting a reading at all on my power tubes. Any advice.

[@MetalKillsRap2]

What about the LBX stealth? They’re el84 tubes. 15 watt head

[@Rummy73]

Cathode bias. You cannot change.

[@pedrolourenco2707]

I've been biasing amps for more than 20 years now. In teh old days everybody wanted a hot amp and then came the cold bias hype. To be honest, using a attenuator and cranking amps, since I dont use super clean sounds, a like a cold bias, just a little above the point where the cross over distortion goes away!

[@fill172]

My stealth 50 was set smack bang on 30, turned it up to 58, definitely not as shrill through the usual frequencies as before..

[@cbphotovideotips]

That was set pretty low.

[@fill172]

It wasn't sounding bad, if anything a bit "ice pick" through the higher end.. I put a TS before it to try round the edges which helped. Now I don't really need the TS unless I want the boost.

[@TheJMan1K]

How’d the low end feel?

[@jimh6391]

Excellent video,thank you so much for sharing

[@markfortuna5664]

Craig, can you tell us where you got your multimeter leads that fit in the bias ports of the Stealth? Thanks

[@kirkkulhanjian9387]

Bump

[@dionr1168]

Will there be a tutorial for the LBX Stealth amp? I know that one has the bias test points on the back, but not the bias adjust. Plus, that uses EL84 tubes.

[@cbphotovideotips]

No I do not own that one.

[@stickit1168]

Appreciate the video. Thank you!!

[@bradleyshuppert3393]

Out of all the tubes you mentioned….. you did not mention…. Mesa Boogie tubes going into this great amp. I just replaced the tubes in my Blackstar MKII 40 watt combo using Mesa’s Red Plate 6L6s and the very rare and sweet SP12AX7 s in both slots…. If it sounds this great in a Blackstar I can only imagine these tubes in the EVHIII 50 watt. It would cost nearly 500 dollars so most people will never know…. But I swear by my ears and fingers how happy I am with tubes that go into the Dual Rectifier Series amps….. super quiet and full of expression and touch and gain in a sweet compressed way….I kicked my dirt pedals off the board and play stock amp gain now….

[@cbphotovideotips]

They are just re-branded tubes. They don’t make tubes.

[@bradleyshuppert3393]

@@cbphotovideotips Correct!! They are STR, Sovtek Russian but tested and graded by Mesa to even get their name on the tube. Randall Smith has a great way to test and if a dual or triple wreck sounds great to you, it will improve this EVH. And honestly…. Before we did any tube changes the bias was set at 30.9…. We ran it up to 59.4 and the amp seemed loud and brite…. So we did the ultimate test of the player playing while I moved the bias around until HE said….. right there!!!! It turns out to be 50.4 was the sweet spot and also quieted the amp noise floor and pedals input…. So don’t forget to try your ears during biasing…. The feel and sound is not a number but a feel….

[@jamessickles1859]

Great video! I was wanting to try some TAD EL34 power tubes in mine but haven’t heard of many people swapping the 6L6 power tubes out for EL34s.

[@cbphotovideotips]

I don’t think you can switch power tubes, probably the reason for the EL34 version.

[@kenaiello4851]

JJ power tubes were in my new 6l6 im pretty sure with the single hole in the center of the plate.

[@cbphotovideotips]

I like a mix of 12ax7 s for a slightly different tone.

[@guitardave]

Really interesting video. I’ve got the EVH 1x12 50w el34 combo, so not sure where the bias points are for that, but I’ll look into it. Would love to hear you play through the three channels of your Stealth head now that you’ve biased and retubed it. Is the gain a bit lower and more manageable now?

[@cbphotovideotips]

Yes, still lots of gain though.

[@RHExperience103065]

How will the Apex JJ‘s work with my 5150 stealth 50 W head

[@rosskrause3926]

They are ok..I have bought them from my online tube vendor and have had zero problems with them ever.

[@speedinbob]

Great video. thanks you!

[@cbphotovideotips]

Glad you like it.

[@nafis6668]

thanks for teaching us. im getting this amp.

[@finchman7654]

do these settings change for UK 230v?or does it make no difference?cheers

[@chrisshultz144]

Do you need to bias each channel on their own? Like how selected and biased the green channel, would you move onto the blue channel or does the first adjustment cover all tubes?

[@cbphotovideotips]

One adjustment all tubes.

[@kgjohnson0240]

What does raising the bias on the 50 watt or 100 watt amp do to the overall life of the amp? Additionally if you were going to take your amp to a tech what would be the best way to explain changing the bias to them?

[@cbphotovideotips]

It only effects the tubes, just say what you want it biased to.

[@kgjohnson0240]

@@cbphotovideotips right. But I tried that. I told them 45mV at the test point across all tubes. They said that it will only shorten the tube life and could cause damage to the amp.

[@metalmaniac17]

So basically, the bias should be set somewhere around 60mvdc (50w version) and that is, regardless of the type of power tubes you put in there? I was wondering if the same voltage applies to every tube. Very interesting video, clear explanations, thank you!

[@cbphotovideotips]

Yes, exactly

[@ricardopereira9262]

@@cbphotovideotipsthat means I can just put a new set of matched tubes without need to adjust tubes again ? Why then the screw? Why don’t leave it always on the same value ? (Ignoring that it can vary depending on the wall voltage )

[@dougfredericks3851]

I just bought a used EVH 5150 III 50 watt with the 6l6 power tubes, the older one with the shared eq for the green and blue channels from Long & McQuade and i checked the bias and it was at 39 and what did you keep your older one set at?

[@cbphotovideotips]

Same as video.

[@arthurreid6108]

Does this apply to the standard 5150III as well? My other guitarist is doing a retube and I'm tasked with installing them because I do my own biasing with my Randall Diavlo head, and I'd like to not bugger it up.

[@cbphotovideotips]

Yes, but the adjustment is not the same. Search for another video for the procedure.

[@rosskrause3926]

With the standard 5150-3 I went inside it and checked the plate voltage and biased power tubes based on the reading..but 55-60 should be ok..I also used the tube socket probes with the power tubes installed into them when doing the bias adjustment.. the trim pot to adjust the bias is inside the chassis..you have to be really careful inside but seems you know what to do.

[@danielholguin1983]

Thank you so much for this video, my 50 watt stealth was set at 40, I biased it to 58 and noticed the amp is warmer upon touch after playing Is that normal? And do you recommend using a auto adjusting multimeter to check the amp? Sorry it’s my first tube amp :)

[@cbphotovideotips]

Tube amps get warm. I just use a basic multimeter. Once it is set you only need to adjust it if you change your power tubes. Let me know if you have anymore questions.

[@JRs-guitars]

Thank you for this video. Is a insulated screwdriver required? I have plenty of common slot drivers but none are insulated.

[@cbphotovideotips]

No

[@JRs-guitars]

​@Craig Beckta thank you for the response!

[@ronnymilianowicz5228]

Is it och the same Bias for the first EVH iii?

[@rosskrause3926]

Most 6L6 power tubes are rated at 30 watts each and thats what my Ivory 50 watt 5150-3 head had in them..the 6L60GC's..so basically yes,

[@CarsAndGuitarsTV]

Great video, I’m Justin on Facebook. You tagged me in this video. Very informative. I’m actually going to try the Sovtek 6l6 tubes you used. I bought my 100wS used and had the same reaction you did. I wasn’t impressed with the amp. The previous owner did tell me he had the bias set cold, i tested it at 95mv! It was definitely cold, too cold. What preamp tubes did you end up using. Im probably going to pick them up as well. My amp has JJs in all the slots now.

[@cbphotovideotips]

I know from experience that it could sound better. I have some new preamp tubes on the way. I will post a video update when they arrive.

[@CarsAndGuitarsTV]

@@cbphotovideotips looking forward to that! I’m going to try to order the complete set. Tube doctor is currently out of stock on the Sovtek’s right now anyway.

[@cbphotovideotips]

@@CarsAndGuitarsTV I have heard good things about their 6L6GCM-STR REDBASE. I think Pete Thorn has a review on his channel.

[@Hadouken5150]

That’s crazy, I have 100w stealth as well. Factory set bias, and it sounds amazing. I boost it with an OD808.

[@brianmeredith4248]

What would the evh iconic 80 watt bias to

[@Altrego66]

Hi I saw you unscrewed the back to change the bios but you didnt plug anything into it. What was the reason for unscrewing that input then?

[@cbphotovideotips]

Adjustment screw.

[@murdock8068]

Does this apply to the lbx stealth as well? Thanks!

[@cbphotovideotips]

You will have to check with Howard.

[@murdock8068]

@@cbphotovideotips Thank you for replying bud. I will.

[@rosskrause3926]

According to my power tube ratings the EL-84's are rated at 12 watts each..so 24 watts total..there are charts online that have the readings available..but using the LBX Stealths bias points on the back I think it will total up to 24 mV / milli volts. I will try it on mine and report back here.. I also have power tube sockets that I use if I decide to check the plate voltage and adjust accordingly to the reading.

[@pedrolourenco2707]

the schematics for the 100 watts says 80mV/mA for all 4 tubes (20mV/mA each)

[@cbphotovideotips]

That is on the cold side. Howard recommends 30 mv per tube. My Marshall and Friedman heads are 36 mv per tube which is on the hotter side.

[@realtruenorth]

Do you, or can you install this setup on my Mesa Boogie tremoverb, as matched quad Mesa tubes are no where to be found lately,, not even from Mesa. I have other matched quad 6L6 sets that I could potentially use, if I could just set the bias to match the amp.

[@cbphotovideotips]

I am not sure.

[@Greg25815]

Thx much Helpfull a lot

[@cbphotovideotips]

Glad it helped

[@KaddysJamKave]

I'm confused... lots of people are saying for eg: That the bias testing ports on the back on the 6505+ are basically useless for testing your power tube BIAS...comments like "They read BIAS VOLTAGE which is completely different than bias current and pretty much useless for telling you anything about how your tubes are biased." But it seems on THIS stealth amp the external bias ports are for measuring TRUE Bias of the power tubes? What the actual heck...

[@guitarforall]

so annoying the 5150 iii 50 watt does not have the bias outside. i gotta take it apart and do it

[@gearwalker89]

I have a 5150 iii S 100w 6l6. I have been trying to check my bias but I am getting no reading at all. My multimeter is set to .ma and after I take it off of standby it still reads 0. Are my bias points dead? I even had to buy banana leads as the thin needle probes werent making a connection at all.

[@cbphotovideotips]

Is your amp on?

[@gearwalker89]

@@cbphotovideotips yes sir.

[@TexasRed420]

@@gearwalker89 did you ever figure it out? having the same problem myself, all settings correct, followed video procedure, got 0.00 for a reading. grrr

[@gearwalker89]

@TexasRed420 No sir. I never got readings from the amp. Since my amp does not need a bias adjustment (at least I don't think it does, it sounds great) I left it alone lol It was very disappointing to think, I spent about $1,800 on this EVH 100w Stealth to find the biasing points don't work.

[@ricardopereira9262]

mA??? See the vídeo again. It multimeter should be set for mV

[@BenGSimon]

Thank you so much for this dude! I'm going to be changing my tubes for the first time ever and this is a brilliant video. So just a dumb question, I know you have to bias...but when you turned on the amp and hadn't biased yet does that not cause any issues? Apologies for the dumb question!

[@cbphotovideotips]

No, most likely if the amp is new it might be biased cold. Mine was 45 millivolts DC instead of Howard’s recommend 60 Millivolts. I have mine set to 58 MVDC because I noticed my household voltage varies a few volts from day to day.

[@zoll96]

mV, or mA ???

[@kxmrock]

When You Variac Down, You'll Have to Reset Bias You Can Verify That With Dave Friedman

[@Behemoth92]

Mine was at 34 from factory ... yikes

[@TheLamboman640]

Hi Craig, new subscriber here. Great video. Question: can you use other power tubes (besides 6L6)? The manual doesn’t say. Thanks, Mark

[@cbphotovideotips]

I don’t believe you can.

[@TheLamboman640]

@@cbphotovideotips figured. Thanks!

[@JJJJ-bg3yz]

Does anyone have Howard Kaplans email address?

[@JJJJ-bg3yz]

wondering if you are familiar with the Easter egg feature on the EVH 5150 100w Stealth? Essentially, if you turn the gain to 10 it affects the gain structure on the opposing channel, great for studio, but not so much for live. In other words, if I want to affect the blue rhythm channel, I can still keep the blue rhythm channel gain around 7 where I like it, but I can turn the red lead channel gain all the way to 10 and it makes the blue channel sound different! Video demonstration attached below. What I was wondering is how difficult would it be to create a modification where I could use the Easter egg feature live and harness the aggressive gain structure without having the opposing channel cranked all the way full? Let me know your thoughts,

[@bobr6055]

thank you, great video

[@robvoyles]

What about the LBX stealth? They’re el84 tubes. 15 watt head