Best Bias Setting for the EVH 5150 Stealth? Tone Comparison

[@msi1985]

Cool video thank you for sharing! Now I'm going to have to check the bias of my 5150 stealth!

[@jcspaziano]

Damn. At first I didnt hear anything significan but the room mic really brought the changes through! Im gonna have to bias up my 34 and 6L6's now! Cheers!

[@BaritoneGoatStudio]

Yeah. Up close the shift is subtle. In the room I could hear a difference, but my ears just perceived it as maybe louder or a bit more gritty, but the mic in the room caught more of frequency shift. I suspect the occupation of the speaker cone changes somewhat with the higher voltage. Being about 6-7 feet back , the mic was picking up noticeable change when gain was happening. Since the is video I have found my sweet spot for voltage around 52mv through the 6L6s on the multimeter. 60mv is also the test voltage at 50% dissipation when they made the amp. In theory the amp could go hotter, but with 6 preamp tubes, I think the amp has plenty of breakup and saturation. I like it a little colder, but 45mv was too cold and a bit stale.

[@nickx1754]

I prefer the fuller body, more umph in the low end and smoother top end of the colder bias. Thanks for this! The bias had much more influence than I'd anticipated.

[@BaritoneGoatStudio]

Is the room it really shifts the mids when standing back. I imagine the voltage affects the way the speakers move. Up close the differences captured by the mic were noticeable, but not as much as the room mic picked up!

[@immyownbestfriend9338]

you sir, have earned yourself a subscriber. great video.

[@BaritoneGoatStudio]

Thanks! This is a test I have been wanting to do for a while. And I was glad I could capture a real result!

[@waynefaircloth3423]

Gotta tell ya. After watching this, knowing that my band is headed into the studio in 2-3 weeks to start the recording of our next cd, I am taking my EVH to my amp guy because of what you showed here. THANK YOU...THANK YOU...THANK YOU

[@BaritoneGoatStudio]

Yeah man! And I was also enlightened to the fact that the 60mv is only at 50% dissipation at the plate. So in theory, the tech could get it closer to the upper limit of 70% dissipation and you may even be able to have a hotter bias than even 60mv! But the tech will know best how to set the bias based on the individual tubes!

[@gravelrocks5588]

Great video

[@TheJMan1K]

I raise mine up to 58 but tbh don’t like the sound through my Mesa 1x12. I think the slightly chunkier low end of the 45V would benefit me well. My bias from the factory was set at 40.

[@BaritoneGoatStudio]

40 is pretty low. I have settled at about 51-53mv as I thought 60mv just made the red channel push too hard into the speaker.

[@brianmcgonigal229]

I have the 6L6 Concentric 50 watter...what would you recomend ?? Around the 53 also...?​@BaritoneGoatStudio

[@BaritoneGoatStudio]

@@brianmcgonigal229 in think they are all built to be pretty similar in how voltage runs. I know the 6L6 has JJ tubes stock whereas the Stealth has Shanguang tubes. I don’t know between the two brands if their plate voltages wildly vary. Low 50s is probably a good way to go. If you feel like you need more harmonic break up in your lower gain channels, you can cold bias to get more of that crossover distortion character. I think the blue channel sounds better a little colder whereas the red sounds better hotter. So I would say try 50-53mv. On the 50 watt 6L6 and the EL34 models, the bias points are inside the chassis. The blue channel on the EL34 also benefits from removing the C137 capacitor from the circuit. You can Google that. It is basically snipping the leg on the calculator inside the amp.

[@brianmcgonigal229]

@@BaritoneGoatStudio well...I turned it on this evening ,heard a hum,then the tube lit up ,,before I could hit the switch,,it blew the fuse...so now,,I had to order fuses since nobody carries the 4am one around here...I have other tubes and will have to bias it ..

[@brianmcgonigal229]

Hopefully...it was just a crap tube...

[@kenaiello4851]

Preamp distortion usually better on the cooler side less harsh I noticed on the old dsl. My EVH usually kept it on spec.

[@BaritoneGoatStudio]

I ended up finding a middle ground between the factory voltage and what the tubes are rated to do. I am currently (no pun intended) running at 53mv.

[@kenaiello4851]

@@BaritoneGoatStudio sounds good!

[@mj-dd2fb]

Even w YT audio limitations, grittiness is def more noticeable with bias set to spec vs factory.

[@BaritoneGoatStudio]

I legit thought the diffidence would be hard to hear, but the close mic definitely captured the grit factor and the room mic almost sounds like a different amp. The extra voltage seems to roll off the high end and push more mids in to the room. I am curious now to learn if the speakers react to the power amp differently when the voltage is higher!

[@mj-dd2fb]

@@BaritoneGoatStudio This helps make up my mind for my next amp .. and I like what you're doing here, keep up the great work!

[@Durkhead]

How much can you push without breaking it? And also i just saw this video where they replaced the tube with a mosfet it was pretty neat

[@BaritoneGoatStudio]

I would say that pushing it much over 60mv might cause damage, but it really depends on the tubes themselves. Measuring the resistance at the plate of the tube will be the most accurate way to tell what the tubes will tolerate. Each individual 6L6 tube will hover around 30ma. This is why matched pairing is important to set a bias that is consistent across the tubes. People seem to find their sweetspot between 50 and 60. I am liking it around 57mv.

[@Greg25815]

Nice Thx

[@nuke1upgames913]

I just got mine brand new and i also own the 5150 III 50W el34 its weird the volume on channel 2 for the El34 head seems louder. Is that because the tubes were changed in the El34 head to El34 KT77 tubes and rebiased ? Gosh i have a lot of questions

[@BaritoneGoatStudio]

I don’t know much about the EL34 model specifically. If they rebiased it for the KT77s you could get more perceived volume maybe, but I would think that it would be consistent across all channels. The only thing I have heard about the EL34 version is the stock blue channel being sort of loose and flubby. People snip the C137 capacitor on the board to fix this voicing issue. Not certain if the stock blue channel voice is louder because of this.

[@kgjohnson0240]

What does it do to the life of the tubes or overall life of the amp?

[@BaritoneGoatStudio]

Increasing the voltage will fatigue the tubes quicker. The amp it self should be fine as long as you don’t exceed a certain voltage. The min risk to the amp is heat. 45mv from the factory ensures a longer life and less chance of failure of the tubes, but it isn’t as saturated.

[@johnwebb2562]

There's a noticeable volume increase In the Bias change around 3 dB on both 🎸 guitars it's giving you more power output. It's just not a big deal at lower gain levels you need to to up the gain to hear the effects of the Bias voltage increase😂. But don't run it flat out for a long period or your o/p valves will over heat , better to run it at 75 to 80 percent from tube manual specs, or lower the plate voltage like Eddy did with a Variac so you can adjust the Wall 🧱 voltage input for different venue's. Good 🤞 luck. John.

[@BaritoneGoatStudio]

I found it sounds best to my ear in the low 50mv range. Like 50-52mv. The stealth is already so gritty on all channels that running it a little colder seems to benefit the sound overall. And when I took into account the room mic, there does seem to be something happening to the mid range being pushed through the speaker with the higher voltage. It was kind of weird to hear and unexpected. Since this video, I have played around with the bias and I have noticed that the higher bias does give the amp more “honk” and I tend to like less of that character.

[@johnwebb2562]

@@BaritoneGoatStudio Hi , around 50 _ 52 mv is about a right it's about around 80 percent power is 380 v x 52 mv = 19..76 watts per tube depending on you plate voltage. If you run it Higher towards the limit too long it'll start to red plate and burn out 🐱 your tubes. I had a Randall Diablo that run on Over 500 v plate at around 50 ma, and it needed a fan to keep the o/p vales cool. So I got rid of the fan and lowered the Play voltage to about 350 v. Now it sounds a lot more harmonically rich and more defined. Anyway 😜 all the best with your musical adventures . Best 👍 Regards. John.

[@johnwebb2562]

@@BaritoneGoatStudio Sorry I meant 380 v x 52m amps= 19.76 Watts.

[@nafis6668]

Cold bias sounds best, not too much low mids.

[@BaritoneGoatStudio]

I like some of the character of the lower voltage. Has a little more chunk when doing palm mutes. The high voltage just gives the 412 a more full sound, but as I push the amp volume in either case the differences get less noticeable.

[@jd5393]

Crossover distortion

[@BaritoneGoatStudio]

Yeah. I have been reading that the colder bias can increase the crossover of the wave form and contribute to the signature brown sound. Not sure if that is legit or just conjecture.

[@ponchochico40]

hi baritone goat,im need your help,im struggling to set the bias of my peavey 6505,it seems that the bias is not in mili volts,is in mili ampers,i set the bias of my amps around 56 mv,but with the 6505 i dont know how is value in mili ampers,i really appreciate your help

[@BaritoneGoatStudio]

If you have an original 6505, I think the bias may be fixed or at least very narrowly adjustable (maybe that is only on the 6505+). I haven't owned any of the original Peavy stuff, but from what I can tell the ports on the back of the amps read the plate voltage and not the tubes directly, but you can use a formula to determine the mA but you might need a bias probe to do so instead of a multimeter. Everything I can find online says that the amp needs a modification to trim the voltage running to the tubes. I would probably go to the archives of rig-talk or some other forums to see if there is a way to figure it out. I know 5150s and 6505 are meant to run colder per EVHs preferred sound.

[@ponchochico40]

@@BaritoneGoatStudio thanks Pal for your fast answer,and your information