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There is two camps of biasing push pull Class AB output tubes is either High Plate Voltage and low cathode Current = High Crossover distortion, compared VS to Lower plate voltage & High cathode Current = Low Crossover distortion. I'm not sure why higher plate voltage & low cathode current will cause HIGHER Crossover distortion? compared to biasing the amplifier using Lower plate voltage & high cathode current will cause LOWER crossover distortion, any reasons why?

If you really want a really powerful really specialized sound go with the tube rectifier. I was able to get unbelievable and insane amounts of sag and chainsaw guitar and all sorts of stuff depending on which stop box I was using which guitar I was using I used to use transistor amps in boss pedals and also what's a butt of gear I wanted to get nice guitar synthesizer 1 day I mean I was gonna go with all that digital stuff that I've been buying trading selling guitar stuff for like 30 years now and the equipment that I now love I did not at all think was the equipment I needed in the beginning I found most of that stuff to be digital and garbage now yet there's analog synthesizes that I like and then I want and their primal permit of screaming out waves of mu trons, moog's, phase shifting the sonic reality of the room. . Last time I played one I was able to create and copy baby that amazing amazing tone from The Isley Brothers saw and called""whos that lady""" trippy CRAZY TRIPPY. psychedelic man. . Would you hear things like indigotta Devita from Iron Butterfly. It's actually probably the first 10 metal song ever dark creepy song people had killed themselves when they saw him come out especially people that were on acid or I mean it was the first really dark and horrific sound one of the guitars so those is just his quiet wow pedal thing it gets a little more distorted as it goes and now the other guitar solo is absolutely insane some people don't even know what instrument it is either barely tell it's a guitar but it's hissing and seething and screaming and wailing totally demonic I've never heard anything else sound so demonic coming out of a guitar and at that 18 minute version there's only 2 guitar solos and I'm telling you you can't miss that 1 I mean it's just trip trippy the voice of the guitar is Living breathing evil and hiss, screaming it's just unbelievable but he is creating buzz saw effects through the Whole song and the rifts. . But spirit in the sky by Norman green bombthe rhythm guitar is his telecaster with the overdrive/distortion/fuzz circuit. Right there in his own guitar and when he Kix that in people said that he got the Sound from damaging the speaker and that's what made it ultra fuzzy and going out of control some people have been able to get a little bit of that kind of thing.

Wow, great detail! Thanks You. I just got lost on the voltage drop used to calculate the current. But to dumb it down for me, say I have a single power tube fixed bios amp... If I were to measure the DC resistance from B+ to the Plate (anode) pin (say pin 3 on an EL34) with the amp off, then turn the amp on (as explained in the video) and measure the DC voltage across those same points (B+ and Plate pin) and plugged those numbers into the I=v/r, wouldn't that give me the current?

Your work in Epic band is awesome!! Are you having anybody over to try out your new projects any time soon? A friend and I did sound for you at Encore bar in Covington a while back

How to remove the overtone

I don't hear any difference, could be my ears being wrecked because of too much loud playing haha. I expected to hear a massive difference though, what does this say about different brands of the same type of tube though, I would likely hear even less than no difference there.

Great video

I usually prefer the Kt66

Excellent. I'm learning and this has been very helpful.

Should have done several double blind tests so that YOU the player didn't know which was which and THEN see if what you "heard" matched what was installed. Would have been easy to have had someone else switch out or not switch out the rectifiers and then try maybe 5 or 10 trials and keep score. Expectation bias could have been a factor here or not. I do know that people say the low end of a tube rectifier amp has sag. Was that evident?

Awesome! Love the sound of the SE stuff. Stumbled on the videos about a week ago

Solid State rectification is for crayon eaters

If you could wire it to run on two of each, that wouldbe the bomb.

There is no mystery about why is the cathode current higher than Plate current. As soo nas you have beaming quattrode or pentode you ill have this "phenomenon". In triodes they will have the same value. You got it already? Yes it is the screen current. Screen takes its own few mili Amperes current. So plus come from the plate from the output transformer and screen gets it's plus voltage from screen resistor or in the case of ultra linear tube amplifiers from output transformers screen tap. In both cases screens have usually smaller voltage than plate. On the tube you have only one connection to negative side and that is the cathode so that is the only place to go for both currents. So Cathode current is Plate current plus screen current. Usually screen currents are a few mili Amperes (3-5 for common output tubes). Also as soon as you do change bias current to new value you need to measure plate voltage that will correspond with new situation. You can't just measure palte voltage and think it is going to stay the same no matter what plate current we draw. It might be sort of logical to think like that because plate currents are mili ampers and that should not make much difference right? Wrong. 5 mA more will drop plate voltage considerably. It will lover it down. When you are lowering the plate current your palte voltage will go up. So you always have to measure both values. To be honest 60 percent is all you need nowadays with the fixed bias amplifiers. Your working currents will reach the maximum value with maximum signal even with 60 percent value. 60 percent is not sounding worse either. Especially not in cleaner amplifiers. Fixed bias amplifiers are more efficient and therefore it is easier and more clever to make a big amplifier with fixed bias power stage. Plus with NFB those big amplifiers will stay usable and not turn into the unplayable monsters. One thing is true we are talking about percentage of the dissipation power and not about the mili Amperes. Though we have to obey the tube datasheet and not overstep the maximum plate current. For example in some nice amplifiers designers use lover voltage overall. They do not care about how to use full power of the tube they are after the sound it self. So for example they do not go with 450V for 6L6GC but they opt to go with 320V. If that would be a cathode bias amplifier to reach 90 percent of maximum plate dissipation you might have to go more than maximum plate current. Then they do leave it at lower biassing current and do not achieve 90 percent. But if that sounds good who cares?? Who cares is it 20 or 30 or 40 watt amplifier? They are after the tone and not the power in such amplifiers. Plus if that turns out to be no NFB cathode bias amplifier with big output tubes and not that much power still it is going to sound bigger and louder than actual Watt numbers would make you think. Think VoxAC30. Not many people were complaining it is not loud enough for what it is. There is no shame in bringing your amplifier for tube change and inspection and biasing to proper tube amp tech. Amplifiers contain lethal dose of DC Voltage. Voltage that stays present in the filter caps even when the amplifier is off. Most of the amplifiers have discharging resistors but those take time to drop the voltage to safe levels. Plus there is a benefit to it. Proper tech will check everything and find if something is lose or broken and your amplifier will be back as new again. Ask me how I know? Well people brought me amplifiers with one issue and most of the times there are more issues. Like one amplifier came to me for tube change and biassing and checkup and I found out that presence cap have had broken hookup wire. Presence can't work without that cap. And that was in really good built boutique amplifier. Once owner got it back he called me after his first gig and asked WTH have I doen to it and how come it sounds so much better now :) Well new tubes, fixed presence and overall cleaning and check up and reflow of few spots does that. Just make sure that if you own really valuable amplifier you do not go to random guy. Often you see bad parts and parts that lower the value of the amplifier. Also if he will not call you after the initial checkup and before he fixes what he thinks needs to be done without consulting you about costs and what needs to be done I would avoid those people. Some people just assume you got money and you want everything done so they just go and do their stuff and charge you after it. You need good communication and pictures and even videos.

GREAT amp!!!! 😁

Built my first tube recrifier, i’ll never go back. Soft start and way smoother crunch. Just perfect

Excellent and very concise video. Thank you

Laney offers Class A amps up to 20 watts.

Interesting experiment. But listening with my Bluetooth earpiece I could not tell the difference. Maybe in person I could. Thanks for posting.

Who would ever listen to this clown show?????

I love KT66, however in the dirty channel. the EL34 has more grit. I can always clearly hear and feel the 3rd-order harmonics in my EL34 powered amp, but I prefer the added noise.. A chacun son gout!

Don't forget about the infamous Fender hybrid fixed/cathode bias circuits, introduced around 1968 and quickly abandoned. I happen to own 2 of those beauties, a 1968 Bassman (AC568) and a 1969 Bandmaster Reverb (AA768). Both had the bias balance (output tube matching) pots, so I added a bias trim pot and use the output transformer resistance method to bias them.

These comments kill me. No matter how ac is rectified, as long as it’s smoothed, there is no tonal difference at all. Because the DC is the same. Difference? Amp manufactures manipulate the circuits to sell you shit. End of story.

Only an armature would trust an amps factory bias test points. Real pro's use a bias meter taking the results directly from the tube. I have proven time and time again the bias testing circuits build in amps are GROSSLY incorrect.

EL34 There is a notable difference in the midrange of an EL34. Online info says the EL34 has a more scooped midrange than the 6L6. I disagree. My ears has always found the midrange in the EL34 to be more pronounced, interesting, and pleasing to my ear. I own several high gain/ high power guitar amps that uses a 6L6 power section. Recently picked up a Magnatone Super 59 M80 that uses EL34's in the power section. The midrange response, especially when driven hard, is prominent and consistent with other EL34 power sections I've used and heard. Whether or not that sound is something you like or not is a matter of personal taste. Keep in mind that speaker selection and other factors can negate this difference or increase it. I'm not getting rid of any of my 6L6 driven amps. But I'm definitely not going to let go of my new Magnatone either. Each amp and sound has its place. They're all good.

The difference is one sounds organic and the other sounds like a big steaming pile of dog doo.

No I couldn't hear The Difference at all Really and it's you should be able to because I have played a lot of old Transistor amps and I got Really Into tube amplifiers and I've played all sorts of news of bunch of different types of power tubes and it creates a lot of different sound even though they say it's just a pre amp tubes that shape the sound and it's b******* because even EL84 like a box doesn't sound anywhere near like EL34 which is Marshall. I played a lot of bands but they're really really old harmony brand 30382 rectify amp just 1 part 2 born premium 2 and 1 direct to fire 2 but it's just a few small components cause 1962 they didn't have circuit boards and all that garbage and when you open up it was really genius looking on the inside I've never seen anything quite like it but those things get consistent tons and sound quality where is I'm looking at spenders and other brand amplifiers are getting 8 and 9's at their best in song quality even my offenders super 60 which is one of the most liked amps out there because it's got 6L6 tubes which is rare for a fender . Most splendor tube stuff I've been seeing over the years this EL84 which I really don't care for and then there is the 6V6 and I really don't care for those either I guess there's a Castillo ray Vaughan type of blues type amp I'm got KT88 which are awesome but maybe a little too much for some people cause that's what the most didoordered like Marshall's and stuff that I've seen you don't see a lot of those around but it's like the guy from slayer or another really heavy bands used KT88I. I used 6L6 amplifiers The most, a lot of brands use it 11:26 boogie being one of the best really great. American sound. . It's very much like the EL34 is in Marshall those are the best sounds I think but little boutique amps sometimes they could make a yo 84 type power tube so good if you've got the right components and like the 2 rectifier ant pie head nobody is using what I consider roll 2 band fires you guys are doing solid State versus tube but yet you guys aren't getting the stuff out of it I get out of it I have taken a couple different types of analog distortions and I've cranked the sand up the song exactly like Norman green bomb spirit and Sky with session in the same amount of sag it's like a truly crazy psychedelic sound I've never knew anybody doing that I've seen a bunch of people playing Santana and I'm all sorts of cool stuff in these boutique amps I'm not seeing any of that kind of smoothness and then these videos and I was able to pull off in indigoted Devita by Iron Butterfly and a whole lot of other sounds that you can't get out of a guitar amplifier anymore. All these so-called newer tube amplifiers are not tubed to me they just sound like too transistor like ever since Steve I had and then I got stolen my 1962 harmony 303 a which harmony is a cheaper brand of back then generic stuff was still good because they didn't have the circuit boards and achieve components from China get equipment like the look almost all the batteries that take 9 V are garbage except for the first ones from the 1960s like the Russian bigmouth get here that on tons of recordings tons and tons of recordings through the 60s and then up again up through the 80s and 90s nineties had a huge reassurance surgeons though it's a band's like Bush and smash and pumpkins and also to them using Russian bigmouth instead of the distortion that comes on the amplifier which is f****** amazing on its own. Sadly they're still promoting and selling Marshall's transistor c*** letting people think that they could buy a martial stack for cheaper and it's really good on like a martial stack no sorry but transistors s*** is f****** garbage and you sit there and play it in a room by yourself without distractions you hear WHY people are willing to spend thousands of dollars for a Tube amplifier instead of transistor garbage that a lot of a started off with. This is like the third video I've seen today and it's still is it's not showing enough of the difference and this is the person who's owned these and I know what I'm a trip but I was getting that alarm and green bomb tone I just used an old analog boss turbo overdrive that weighs like 20 pounds and I crank that going into the amp I turned up all the knobs my volume knob turned up all the knobs on the pedal all the knobs on the app with the exception of volume just to use that the control of the volume and it was insane troopy sagginess nerves also all sorts of crazy other tones coming through there too that sounded familiar to me like psychedelic stuff futuristic stuff a little bit like Rock and roll fantasy by bad company is It's a Synthesizer guitar From the 70s used on that song and it's got a lot that analog crazy distortion sound . So I was able to whip the sag around just like that just unbelievable trippy and then I was able to twist the pedal around to do some other stuff and I was able to get the sound from in the gotta Devito by Iron Butterfly which is like a f****** buzz saw one of the solos he does in that song is amazing it sounds demotic sometimes you can't tell guitar what it is but yet psychiatrist doing some amazing ship that demox owned is solo people used to take acid and listen to that song it's supposed to be people to kill themselves and stuff the long 18 Minute version of Iron Butterfly and their song indegattadavida. is very demonic and very Powerful. . That's the first psychedelic and also the first metal sound there wasn't much dark metal type music ever before that the kink's being like going to talk back to using power chords at that time.

there are 4 diodes in a solid-state full-wave bridge rectifier, not 2.

Thanks for the informative video. What does it usually mean if the bias is drifting a lot? The bias on my two rock studio pro 35 amp test point varied from 0.054v to 0.074v during a gig after I set it at the recommended 0.064 initially! Also the test point feels soft with the multimeter probe almost like I’m stabbing it into play dough!! I’m so confused!! The tubes are new and quality matched tested ones so unlikely to be the cause.

The only important difference is that with tube rectif you will never get AC into circuit( if tube goes off any current stops) if diode is damaged it is not so good

Very stark in 60’s Ampeg Rocket vs Reverberocket. Haven’t looked at the circuit but ver different sounds. Great clear explanation.

Cut the intro down for God's sake. Sounds like a day at Guitar Center. 😂

Interesting. Thanks for the video.

For me I think that a great amp as a pedal platform is a JTM45 clone amp with KT66, when using heavy distorted pedals I think that the KT66 sounds better in a JTM45 compared to the EL34. It seem like the KT66 have more dynamics than the EL34, some people would disagree with me on that but in my opinon the KT66 is super great tubes. I don't know any better amp for a pedal platform than JTM45 or some sort..

Great video man. I have both ss and tube amps. I'll take my tube amp over my ss anytime. Tube amps have a more natural sustain clean or dirty, the ss when holding a sustained chord breaks and cracks before the notes die out at the end.

KT66

6L6

6550

The differences are so subtle that you will never notice them on a stage playing with a band. In that case, I would always go with the SS rectifier, as they are more reliable. However, it should be pointed out that if you change your rectifier tube out for a SS version you will almost certainly increase the voltages supplied to the plate etc. of your tubes. Be careful. Don't cook your tubes. On my Vox AC30 CC2, the GZ34 puts out 352VDC with the amp running idle. With the SS rectifier, 374VDC. Way too hot IMO. Amps where the ability to switch in/out an SS rectifier is designed into the amp itself will be just fine, but be careful when swapping your tube rectifier out of your Vox, Fender, Marshall amp etc.

The El-34's were better with the gain, just had that great growl and compression in the midrange. The Kt-66 had a nice clean tone, but seemed a bit stiff and hard 😅 distorted.

I don’t think your calculations for cathode bias are correct. Plate voltage is with respect to cathode, not to ground, so plate dissipation Pd = (Va-Vk) * Ia.

There's one more important thing I forgot to mention about the Tube/SS rectifier switch. An additional benefit to having this switch is that if the tube rectifier goes out for some reason, you can switch to the SS rectifier and be good to go. This actually happened to me at a show one time with the RC30. At the time, I could only get my hands on a cheaper GZ34 rectifier tube and that's what was in the amp. I went through soundcheck without an issue, but when it was time to start the show, I flipped the standby switch and there was no sound. I knew right away in my head that the cheap rectifier tube had blown. I quickly switched to the SS rectifier and the amp came back to life and I proceeded to play an almost 4 hour show without any issue. Afterwards, I replaced that bad rectifier tube with a more robust one and haven't had an issue since.

The EL34 sounds good on this amp. The KT88 had a honk to it that would probably be a good choice for a live 2 guitar setup that would cut thru maybe a little better. Superb tones for sure.

6550

Excellent channel. I hope you get more subs. I like your amps too.

How about this -20 volt....and I need -13 volts...show me the circuits to get negative voltage.

SONICTONE< you didn't show how you measured or calculated the plates voltage drop? once your got the plates voltage drop * bias current = tubes power dissipation, how do you compute to get the tubes power dissipation?

Great vid thanks.

I fully expected to prefer the EL-34’s but I found the KT-66’s more pleasing to the ears than the EL-34’s. I’m a big fan of the Soldano sound so I’ve always liked the KT-88’s .. But for what I do (mostly small bedroom) they’re pretty unpractical..

Damn it, I prefer the tube one (but my amp has ss.) It's more noticeable on cleans. I guess because the distortion is already adding sag/compression.