Class A v Class AB Explained by Santiago Alvarez

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00:00 - Welcome
01:01 - The AC30 Isn't Class A
03:05 - Class A v Class AB
06:05 - The Bicycle Analogy
09:50 - Ac30 Caveat
10:41 - Crossover Distortion
11:59 - Audio Example
12:28 - Character Tones
13:25 - Negative Feedback
16:05 - Bringing It All Together
18:51 - Sag
22:06 - More Audio Examples

[@LeonTodd]

What other amp topics would you like to see covered on another video?

[@kenclark4193]

very very very very interesting, thanks Leon. Both this talk and the other podcasts raise the quality of your channel to a very high level. The clarity of the explanation and kindness with which he explains it are impressive, fascinating. Like others have said, who isn't imagining a couple of cyclysts inside the power tubes? LOL This man and that analogy is at the genius level, we want him to explain everything to us nerds! Pickups, cables, impedances, headroom, feedback, pedals, power supplies, tone controls, speakers, everything!

[@peterharvin2775]

Best explanation I've ever heard. And delivered with no condescension at all. What a great guy.

[@LeonTodd]

All absolute legend!

[@CamiloVelandia]

Man! I have to watch just that bicycle analogy like 3 times over and over. What a great way to explain!

[@LeonTodd]

So good!

[@jasonktong1]

Great. Proves that it takes incredible understanding of a topic to be able to then explain it simply.

[@LeonTodd]

Beautiful analogy isn't it. What a guy

[@santiall73]

thank you!

[@joerobertson795]

Wow! The "Bicycle" explanation is incredible. Even a dumb guy like me now understands amplifier classes, bias, and sag! Excellent vid

[@LeonTodd]

I love it!

[@heavybrett-al4082]

OMG....I watch....I learn....I love... fantastic talk, what a great why to explain it. So cool.

[@jtbranman]

This video and the other one with Santiago are great. Thanks to both of you and Troy too. Also, it was nice having Michael on the gear podcast. He's a great guy and very helpful like yourself. This stuff is pearls. Thanks!!!

[@LeonTodd]

Our pleasure!

[@brutallyremastered4255]

What a terrific analogy and engineer.

[@primaballerina84]

Blessed are we who can listen and learn from such a humble genius! Thank you for this Leon!

[@LeonTodd]

Absolutely!

[@rickard9294]

Very nice video! I liked the bicycle analogy. Thank you!

[@RobinStrower]

Santiago is the man.

[@billyarsenault1970]

Well worth the effort- his accent only made me pay attention even more. Brilliant man and the father of my beloved Satch JVM. I am willing to bet I have struggled with the tone of an an amazing amp that was just biased too low and then thinking it’s not for me and moving on for no legit reason.

[@hoosierdaddy2308]

Sorry to write again, but talking about Vox amps so much made me think about when I saw Rory Gallagher. I was thinking he used Vox AC30's.. It might have been fenders, but he had a bunch of them and his famous Strat and I think a Tele with a capo he played too! I saw him open for Rush and an older guy I went to the show with said "Man make sure you check out Rory too" because he knew what a huge Rush fan I was.. I was blown away by Rory.. I mean just blown away.. He was so sooooooo much better live than his records sound to me.. He just came across as one of those guys that you had to see his live show to really get it to me.. What a great blues guy! Great stuff..

[@LeonTodd]

Holy shit I can't believe you saw the great man live!!!!

[@hoosierdaddy2308]

@@LeonTodd Yeah, it was great man! I loved it.. I couldn't believe how good he was.. I was a fan from then on ! You can imagine what a great show it was with him and Rush playing last!

[@StratsRUs]

Thanks.Just the sort of conversation that I find fascinating.Great explanations

[@LeonTodd]

Glad you liked it!

[@rayjames433]

thats the best description on the difference between amps great analogy now it all makes sense brilliant great vid cheers Leon✌

[@LeonTodd]

Glad you enjoyed it

[@seventhsealhere]

Tasty interview. Great to see Santiago on the channel. I think an LT signature amp should be discussed 👍

[@LeonTodd]

If I ever had a signature amp I'd want Santiago designing it.

[@santiall73]

😉

[@AudioAtmos]

Excellent video…Thanks Leon!!

[@ludvanlazarz]

Amazing! Love this interview! You two are really great together in conversation 🎉

[@LeonTodd]

Glad you enjoyed it!

[@rutger4131]

If you want to listen to cross over distortion let your guitar signal flow through a antiparallel pair of diodes (use EMG pickups or a booster as a preamp). Depending on where your guitar signals is in its cycle one diode will be blocking signal and the other will only turn on above it's threshold voltage (about 0.3 V for germanium or 0.7 V for silicon). In a high gain circuit, with lots of amplification and distortion, you can use diodes with a low threshold voltage like Schottky diodes (0.15 V) as a noise gate. The little bit of cross over distortion will be negligible to the other distortion and the signal will we ~4V peak to peak so the diodes will be conducting most of the time. This is the basis of the noise gate in the Tight Metal pedals.

[@LeonTodd]

Interesting! Unrelated but I'm tempted to grab an EMG 81/85 set to put in a PRS just because

[@rutger4131]

@@LeonTodd PRS Torero style ;)

[@santiall73]

yeah, I think the first one I saw using diodes in antiparallel was the Boss HM2 pedal. Then it is present in many of the James Brown designs that he did for Peavey (Rockmaster, XXX, Valveking, etc. etc). I think he designed the Tight Metal pedals too so there you go

[@sadwingsraging3044]

I had more trouble understanding _him_ than understanding the concept as he was explaining it! Ruddy brilliant way to explain it!👏🏻👏🏻👏🏻👍🏻thanks

[@santiall73]

I'll take that as a compliment hahah

[@sadwingsraging3044]

@@santiall73 it is more than just a compliment. That explanation was so simple in its concept that it was like a retired professional BMX rider trying to remember how to ride a bike.😊👍🏻 My hearing, too much Metal in my youth, combined with your accent made for a right struggle to decipher until I could process it a bit and you had spoken your vowels along with any strange consonant pronunciation particular to your mother tongue. After that it was smooth sailing except when the concepts you related broke my brain in such an easy to understand way.🤯👍🏻

[@santiall73]

@@sadwingsraging3044 glad it finally worked!, I know my pronunciation is what it is... luckily I am not being paid for that one :D also very pleased that the explanation was useful !

[@sadwingsraging3044]

@@santiall73 Your accent is great and your English is fantastic.🤘🏻😎

[@santiall73]

@@sadwingsraging3044 now that's a compliment :D cheers!

[@peterschaefer1665]

Great analogy Santiago...love it. Even I can understand that!😅

[@santiall73]

thank you!

[@tamirkeren6750]

I learned alot. Thank you.

[@wagnernoise]

Nice explaining! Great video btw! Cheers

[@LeonTodd]

My pleasure

[@hoosierdaddy2308]

Wow.. Couldn't click fast enough when you had him on here.. The pod cast was great and what a great guy who's so smart.. Man, he makes me wish I had studied electronic engineering back in the day.. 😛 Class A, Ab, C, etc.. is so interesting.. I love this nerdy stuff.. 😛 The bicycle analogy had me cracking up! It works though! Whatever works! So interesting.. He's such a good guy and so smart.. I'm really happy you did this show sir.. Great stuff, but I'm a nerd man! 😛 I loved the playing in the video to use as an example. Thanks brother! Very cool.. I'm so nerdy that recently I was arguing with people about the Coriolis effect on shooting at long range.. The earth spins fast, but it's big.. But, it has an effect when your bullet is 1000 yards or meters.. As well as bullet spin, the ogive of the bullet, the sectional density, something called the ballistic coefficient, etc.. There's a couple from Australia I watch that shoot out to two miles.. I think they are in the east near Sydney or a few miles from there in the country side.. They shoot very long range.. 🙂 Great show.. Leon, your cat was behind you trying to get a place to lay down no matter if you were recording or not. 😛 Thanks Santiago.. Man, please come back on often and explain this stuff to us nerds. It's most appreciated sir.. Really really adds value to my gear life sir! Be safe Leon and Santiago and family! Be well ! Tim South Central Indiana. (The heartland) USA)

[@LeonTodd]

If you like shooting there's some great spots in Australia - we've got some seriously flat land here!

[@hoosierdaddy2308]

@@LeonTodd would love to see it brother!

[@Angellus502]

@LeonTodd Any chance of getting some sound samples of slightly and moderatly under and over biased? I remeber one of my amps used to sound just plain angry and nasy in a killer way. Then once it got new tubes and was baised it lost all its angry coolness :(

[@martincockburn6821]

I could listen to him talk amps all day... That was a really great way to explain it too.... Everytime I play I'm just gonna see a little dude riding a bike inside my Marshall now tho 😅😂

[@LeonTodd]

Tandem bikes in the big amps!

[@martincockburn6821]

@@LeonTodd 🤣🤣

[@NikolajChristensen]

What a fantastic analogy :)

[@PerryCodes]

Great topic Leon!

[@LeonTodd]

Santiago is the man!

[@peterschmidt9942]

Like most manufacturers they all claim outrageous specifications and its all about marketing. Class D amplifiers are basically switch mode amplifiers. They operate as electronic switches (as in pulse width modulation PWM around the power rails), and not as linear gain devices as in other amplifiers. The downside of this is it can block the high frequency. The upside is they are always either in fully on or fully off modes, little energy is dissipated in the transistors and efficiency can exceed 90% efficiency. The difference from class A to AB can be significant in terms of sounds. While class A has little to no distortion,, there's an inherent lack of power efficiency. So the power output of these amps is generally in the lower output range (5-30W), Plus you have to take into consideration that class A is on pretty much all of the time hence why power efficiency is low on these types of amps. While an AB configured amp will have better power dissipation ,there's can be a little added distortion while the signal changes from positive to negative (while transistor or tube turns to B in push.pull) Thats the bias part of it. The inherent feel of the amp and sag of the power circuit unfortunately is due to bad electrical design. None the less its part of the sound of certain amplifiers.Some players love it and over curse it LOl

[@rockstarjazzcat]

Sweet! ❤

[@rockstarjazzcat]

🚴🏼‍♀️🔥

[@rockstarjazzcat]

Thanks Santiago! Thanks Leon!

[@babagadoush1]

Finally I understand

[@SuperCMO79]

I like to ride my Bicycle :D