What's so good about SET amplifiers and efficient speakers?

[@kindface]

Your explanation is absolutely the BEST among the YT videos I've seen that explains the SE and the PP difference. Huge kudos to you! The rest of them starts flipping out some white board or paper and start scribbling diagrams that confuse more than elucidate. You did use diagrams too but dispensed with all the noise and clutter about high voltage, transistors, etc. I totally get it now, at least the essence of the difference. We just want to know the operating difference, not the "rocket science" behind them which is what all the other videos tried to do - and failed!

[@wa4aos]

I agree 100% regarding SET and efficient speakers. I have built amps running 45's. 2A3'a and 300B's and several that I can switch between 45 and 2A3.. I have built my share of PP amps and they were very listenabld but SET is just captivating. I have a pair of back loaded horn cabinets I built in the mid 90's. Each cabinet weighs 146 pounds and there is no cabinet flex at low freqs which brings more lows out the front. I have ran both Lowther 2A and 6A speakers as well as a Fostex single driver in these cabinets and they all sound amazing. Soon I;m going to build a sub with FETS and build a sub box with 2 )12" drivers or 4) 10" drivers. Need to play with the math and see what makes sense. One thing I will add to you description is the speaker crossover distortion in addition to amp crossover distortion you mentioned. That plus SET has virtually no slight lag time. When the signal is there and changing, the output is right there. I also agree there is something that science can't explain about the purity of such systems. The THD is decent but many SS amps are far better but sound harsh. Of course, maybe the real magic is our ears and how our brains interpret what we hear. The designer of that arrangement is trulley and awesome engineer... Again, enjoy your videos and glad you are sharing your knowledge with a new generation. Maybe I'll get off my duff at some point and put up some videos as well. 73, Glenn WA4AOS

[@Blueglow]

Would love to see you make some videos. I just do this as a hobby and wouldn't consider myself a pro but having fun none the less.

[@kindface]

You sound like an expert. What a pity you prefer to inundate the world with it and with your opinion remotely, instead of presenting them on a video for the world to see.

[@wa4aos]

@@kindface You worry with your issues and butt out of mine. I am free to comment as I desire just as you have done so by insulting me. It's trolls like you who insult people, this was a 5-year old post, who discourage many including myself from sharing my vast knowledge as an engineer with decades of experience only to have some low IQ nitwit insult my efforts.

[@deruebersau]

Thanks Mark for an exposition of this subject that an average fellow can understand. 100% Full Duty Cycle means budget for (very likely) bigger electric bills! The sweetest two-way horn speakers I've ever heard are the Vitavox CN-191. The Fostex single drivers are deservedly well regarded. If one has the budget, the Lowther TP1 also deserves a listen. I personally own Klipsch Chorus II and KG4's. The Chorus would probably perform well with a SET, but that's not what they're paired with now. Listen before you buy!

[@helmutdiggy6874]

Great explanations , I appreciate you making these videos.

[@emildejong1226]

Thank you for helping me to understand a bit more of this complex (to me) subject, Mark. You’ve made it easier for me grasp a bit more of it.

[@drbarney1000]

The simplicity of the single ended triode amplifier makes it easy for any amateur to build one if they cannot afford to buy a manufactured one. One solution to the low power is to use an 833-A triode. I use this tube with transformer driven 245 by step down transformer to the 833-A grid and a Hammond 1642SE output transformer and 1) the speakers need not be as sensitive and 2) the bass is not so weak as it is in most SETs.

[@srtamplification]

It can all be summed up in one word. Fidelity!!!

[@obscurazone]

I would say two words that lead to that fidelity: Sensitivity and efficiency across a system.

[@srtamplification]

@@obscurazone Efficiency is inverse to fidelity. Class A amps have the greatest fidelity, but lowest efficiency. That is why it is important to have very efficient speakers with a Class A amps, as to waste even more power.

[@obscurazone]

@@srtamplification Erm, exactly. I said "across" a system. If you don't have efficient speakers, and you're running SET or class A SS, you're not getting the fidelity. Hence why I said efficiency and sensitivity are what LEADS to fidelity. Merely stating "Fidelity" is meaningless.

[@andreas7278]

What an excellent video on this topic! Regarding your last statement "if there were science behind this it wouldn't be so controversal": Well for sure there is, it just often takes a lot of time for humankind to find out truly what it's all about. A few things that we already know from science today w.r.t. SET amps which you did not mention here are: 1. Those DHT tubes operate at a vacuum, a very large spacious one even. That's the best dielectrica known to mankind on this earth. You simply can not get any better than a large vacuum. This means that there is hardly any capacity to speak of (nothing is truly perfect but it's basically gone) and there is no chance of any coloration of any kind. So when you then couple this with a very high quality filament you get something that even the best of the best FET or bipolar transistor amps are very far away from. Want some practical evidence as well? Strip the plastic crap insulation from bipolar transistors from your SS amp and see how it sounds. :-) 2. Low order harmonics: These DHTs only produce low order harmonics, none (not little, just none) of those nasty high order harmonics. You only get this here. Human hearing is based on only low order harmonics. Literally we create our own distortion (up to even 10%) of low order harmonics inside our ear canal. There are scientific papers about this going into great detail if someone is interested. The distortion created there has its own shape which varies greatly based on amplitude and frequency. We as humans actually are used to hear distortion all the time since we literally don't receive anything undistorted due to this. However, our brains are used to this unique distortion pattern and anything other than that sounds ... well unnatural or you could say distorted. While the harmonic distortion spectrum created by DHTs are not the same as the ones created by our own ear canal it comes somewhat close to it. So it's not perfect at all but when you see the distortion patterns created by bipolar transistors or FETs and how extremely different they look like, well then a bell will wring in your head. There are even scientific papers outlining the psychoaccoustic perception of the human brain to different distortion characteristics. This is also the scientific reason why a high quality SET amp driven quite loud does not sound harsh/distorted to us and we feel like we can just continue listening for extended periods of time at quite high volumes (given the rest of the chain does not add some pretty nasty stuff). On a sidenote, while speaker cones, especially the bass ones, have quite high distortion, compared to distortion in modern amplifiers it's not really an issue as long as we stay low enough (way below our 10% of the human, so sufficiently large drivers for the amplitude) since just like tubes the only produce low ordered even order harmonics which are very similar and, thus, pleasing to the human ear. If it weren't like that we could just ignore distortion level of amps since those speaker bass cones would make up more than 99% of the audio chain distortion anyways. The reason the amp distortion however matters quite a bit is that apart from SET amps the distortion pattern created by other amps is psychoaccoustically very unpleasing for the human. So they have to be ridiculously low in order for us to be bothered by them and still they are "not quite there" since we can't get them to 0. 3. High quality DHTs are very linear and a lot of stuff has to be done trying to correct for them. From biasing to all kinds of sound coloring and signal harming things inside other amps. 4. They are high-bandwidth devices which is awsome since there is no clipping distortion ever. You can have one of the best amps in the world, if you ever just barely clip anything it sounds harsh. By massive design-overkill in very expensive amps (massive indeed, since in order to have so much headroom that you never ever in any musical peek in a dynamic passage you will not get to that point) due to the logarithmic behaviour of amplitude (+10dB -> 10 times the power) you need to design for that overkill. This not only makes amps super big/heavy/expensive but also due to the massive amount of parts used any coloration, noise issue, out of phase, differently specced components etc will multiply their negative effect. To a large degree this can be nullified with using crazy expensive parts and extremely tight component matching but not completely. Given the same quality of parts and matching you will never get to the same level. I am sure there are even way more reasons that I am just not aware of, forgot to mention here or are simply not yet understood well enough but as can be seen there are quite a few scientific reasons why they sound remarkable when done well (and put into a system where their downsides can be dealt with adequately since they also have a couple of disadvantages). They certainly don't work well in any audio chain out there but in those where they do they deliver a very natural, authentic and even uncolored sound.

[@alexandernaydenov7400]

Some people believe the dominant harmonic distortion gives the specific SE sound, but from personal experience I think, the less any amplifier distorts, the better is the sound. In fact, you can build a multiple local feedback SE amplifier, that will give you low distortion resulting in the combination of excellent performance of complex dynamic music. This kind of "SE magic" is not related to distortion.

[@sammys7518]

There are at least 6 other types of distortion besides harmonic that affect the sound, and SETs produce them. (Distortion is anything that alters the sound.) True, some designs exaggerated second harmonic to define the sound, and also masks higher orders. The sound quality also depends upon what one's reference is. Anything will sound good if the reference is the local bar sound.

[@boblochen]

Nice presentation.. Thanks for the tutorial!

[@BlankBrain]

Another way to get more sound out of lower-power amplifiers is to tri-amp. Admittedly, active crossovers add a noise source. But by eliminating passive crossovers, the only thing between the output transistors and voice coils is wire. This allows the damping factors of the amps to be fully realized. I use large enough amplifiers that they are almost always idling. I use bipolar for bass and midrange, and Sony V-FET for treble. As a rule-of-thumb, at least half of your audio equipment budget should be invested in loudspeakers. I started with the dB I wanted to accurately reproduce, and worked my way back.

[@bobsmoot8454]

IMHO, the sound of a sound system is more influenced by the conversion of energy types. Meaning whenever you are converting energy, such as mechanical to electrical or electrical to mechanical, has more chances of generating distortion. The synergy some people perceive when listening to SET and efficient speakers, I would dare say lays more with the speaker. Again, my opinion, an efficient speaker reveals more about what is in front of it and again my opinion, efficient speaker allow closer reproduction of dynamics and if chosen wisely play cleaner at volumes closer to what we hear at concerts. The ability to execute dynamics I also think lends greatly to differentiating tones, which are comprised of many harmonics. After 60 years of listening to tunes, I’d advise someone to buy efficient speakers, unfortunately, large cabinets or baffles are an integral part of that solution. Again, just my opinion.

[@robertyoung1777]

I think contemporary speakers tend to have more complex crossover designs in an attempt at getting big sound out of small boxes. What is lost is efficiency. For example; my new JBL L100s are 4 ohm - my 1979 JBL L100a speakers are 8 ohms. The old version sounds much more lively but sacrifices detail. The new version has better detail whilst sacrificing the nice open sound of the 1979 L100a speakers. That a in L100a matters. In my experience the L100a version is the best of the vintage JBL L100s.

[@kenmicallefjazzvinylaudiop6455]

Thanks for the excellent explaination.

[@todddembsky8321]

Your number 3 is the reason. Listening is so subjective, it is all about finding the correct speakers putting them in the correct place, for the type of music you listen to. That is the magic. I have had some high end speakers that were darn near flat on the frequency curve, and they sounded so cold. They actually would be painful to listen to for extended times. same reason vinyl sounds better than CD. Our ears are just not designed to listen to music that is square wave.

[@turnersparadise8368]

lol, you see people in the strangest places. I know you from Fresh P's channel.

[@todddembsky8321]

Absolutely. Corrin has been very quiet lately. I really think that her hip replacement and the KZbin censoring and demonetising was just too much. I am refurbishing a Dynaco ST70 so I watch Mark to know what wires not to cross :-)

[@turnersparadise8368]

I have a Marantz 4270 which brought me here and Mark has hooked me. I was seriously thinking of building the Triode Dick 807 SRPP for a first build but now he has me hesitant. Maybe I need to see his next build before I make the jump. I have thought about a Dynaco 70 or more to the point a new Bob Latino ST 120 kit but think I want to try building a smaller single ended amp from scratch first before I really invest.

[@todddembsky8321]

Yes, the SET build series was extremely interesting. I would not be afraid of the Bob Latino kit. A little money, but I have his upgrades in my Dynaco, go in easy, sound great, and I could use my WTMW speakers that I built from plans from Parts Express. Sound great, but need a touch more than 8 watts. Hey, did you ever let your son use the mini lathe that you got him for Christmas then you swiped for turning pens? He has to be 17 or 18 years old now.

[@turnersparadise8368]

hahahaha he tried to turn a pen the other night....He is going strong on 17 with a serious girlfriend...Yeah, 8 watts, I hear ya....Got the Skipjack finished. Time to turn over a new leaf....Cranking on some Hank Jr. now. I miss Corrine...Glad she and Wstar are back on speaking terms. She just divulged too much. Glenn put his foot down...Yeah, I miss her but all is well. Take care, Todd.

[@V1ralB1ack]

It makes perfect sense to go the set route with crossoverless single driver speakers. What better way to design a crossover than no crossover. The time and money on the crossover now goes into a perfect driver. The set amp is not push pull and each channel powers the full signal no pushing pulling or tearing nothing lost but everything to be gained. At a 6.5in single driver speaker a person should be able to enjoy detailed musical paradise.

[@rickg8015]

Where to start? The back issues of the defunct Sound Practices magazine from the 90’s.. i think you could still get them on cd-rom - complete. I must say the most difficult part is selecting the right speakers.

[@kesm66]

Thanks for the input. I’m building a low watt amp set up. I ordered Omega Super 3 High Output speakers (97.5 db). My chain currently is PC USB > Border Patrol SEi DAC > MZ3 Linear Tube Audio Preamp/Amp. I’m thinking to add an First watt SIT-3 amp into my chain if the LTA doesn’t offer enough watts for dynamic peaks. My only reservation with the First Watt SIT-3 is its physical size for a desk top application (floor amp). Can you recommended a desk top sized SET amp that would offer the same magic?

[@petercornell2002]

Hey Mark, nice new intro sequence!

[@rezakhyabani725]

Hi, I was wondering if you have ever designed high end mosfet power amplifier and high end tube preamplifier. I would appreciate your help.

[@davidrapalyea7727]

I am curious about the sound profile of my Marantz 1060 I run into period speakers the KEF 104. Have you heard anything about such items? I like them but I don't have much experience. For comparison sake I just bought a Chinese Reisong single ended A10 EL34 and Klipsh Heresy. That will give me some mix and match opportunities to report on!

[@tee-jaythestereo-bargainph2120]

Synergy- I own over a dozen speakers and a also a dozen amps , And your correct that one speaker isnt better than another its just depends on the marriage or Synergy - last night i rolled 8 speakers with my New Omnia amp by Audiolab . and all my speakers were just sounding ok but as soon as i hooked my Kef speakers up to the Omnia omg Synergy was on 🔥

[@blejzerosamigos6115]

Hello, I connected A50 mk3 7.6w to my Sonetto viii 90db sensitivity 4 driver's floor tower speakers and I don't even need to go pass 10 o'clock on the volume knob it's that loud and it sounds awesome.

[@ujean56]

I'm not at all sure you are being "subjective". I am convinced that either single ended throughout (pre & power) or single ended (pre with SS power) is the way to go along with high sensitivity speakers - preferably open baffle. The combo is truly magic and I have heard only very expensive solid state rigs come close. I think there's a reason SS amps try to emulate the "tube sound".

[@robertbowes1829]

Mark I have a pair of Goldnote S6-XL speakers, they are 90db @ 6 ohms and was looking at driving with a Unison S6 tube amp. What is your thought on this? Thanks

[@MyIDIsNotAvailable]

s6 has got lots of power.. it will drive almost anything you wanna conect it with.

[@robertbowes1829]

Mark I ended up purchasing the unison sinfonia anniversary amp. Also got the simply phono by unison.

[@rondrew1]

Excellent explanation Mark. Thanks for this video.

[@sammys7518]

The video is basic nonsense. What he describes with the notch is Class B operation. In reality, Class AB push pull allows both output tubes to run Class A for X amounts of watts until sliding into Class AB1. Also, the signal is Not taken apart and put back together. Hope this helps.

[@goaway2174]

Hi Mark, I agree with your explanation in general. Finding the appropriate speakers is important but I don't believe that you need high sensitivity rated speakers to enjoy these amplifiers, the impedance curve is more critical. I have partnered speakers from 88 - 90 dB/m with 6.5 W (EL34) , 8 W (KT88), and 18 W (6C33C-B) SE amplifiers and all of them played reasonably loud and sounded clear. 95 - 100 dB/m is sufficient for most of my listening. If you need concert levels that is another story but it isn't typically found in systems based around SE tube amplifiers.

[@mosfet500]

Class D with a single ended triode preamp. No crossover distortion, high power, drives anything, sounds great.

[@julior3753]

Hi Mark, would you please kindly check my beautiful Grommes LJ amp, possibly made by Philips on 1960, and tell if it is a class A SET or not. It has all the original Grommes label tubes: 4 X 6EU7 ; 4 6BQ5 and 1 Philips EZ81 rectifier. In addition it would be great if you could kindly explain in general how to identify as Class A SET amp.

[@sammys7518]

That is a push pull amplifier design. Only two output tubes, assuming left and right channels is SET. Hope that helps.

[@larryshaver3568]

when did 300B tubes first come out?

[@rightslot1]

I am considering a 8WPC SET tube integrated. I'm sure some are better, so anybody have thoughts on 2 or 3 of the best--small bookshelf type speakers? I keep hearing that the Klipsch will fatigue after a while, so I'm looking at something else. THOUGHTS???

[@BourneAccident]

Awesome. Helped me a lot. Thanks.

[@sammys7518]

What a shame as the information presented is almost entirely false. Read my above posts.

[@BourneAccident]

@@sammys7518 Almost doesn't cut it.

[@sammys7518]

@@BourneAccident Please explain. What are you saying? Thanks.

[@BourneAccident]

@@sammys7518 No biggie, but "almost" entirely false is somewhat misleading. Honestly, I have yet to read your other posts. I will do so.

[@1mctous]

How a tube distorts when overloaded goes a long way to explain its sound, just ask any guitarist. But below that level triode distortion closely mimics the human ear's, as Harry Olson established in the early 1950s.

[@jesusiscomingrepent6625]

I have three fifty-year-old Cerwin Vega Power amplifiers solid-state the first ones made for the movie / The Poseidon Adventure and earthquake in Censoron. A1800 A1800M A3000i from EBay. I had the filter capacitors replaced but the old capacitors still work there is a difference in sound with the new ones should I continue using the old ones even though the amps are over 50 years old.. The capacitors were tested and they're still functioning within specs but because of the age I had them replaced....

[@dachanist]

TLDR - the science is in amplitude depth and speed of amplitude response aka headroom/imaging/detail You have a far greater understanding of the science than I do, but there is definitely science behind it. Number one is that its a Class A amp. You send an electron in and it gets multiplied. It doesn't get delayed and re routed and turned into a square wave and yadda yadda.. it just gets multiplied at the speed of the electrons in the circuit. Number two is the volume of the multiplication. Its like asking why does a church have great reverb? It's because it's so fucking big! So, Class A with direct path from source to speaker - You have amplitude response not just frequency response. The reason guitar players love tube amps as much as they do is because the wave from the pickup is unbroken and magnified to the speaker cab, not bit crushed. It's like using a magnifying glass on the sun vs taking a picture on a cell phone or a 35mm and zooming in. People talk about the magic of tubes, and that"s wrong (in my opinion, I'm a musician not an engineer). The magic is in the multiplication of electron flows due to the physical properties of the circuit. Why don't transistors sound the same? The biggest reason IMO is because they aren't working with the same volume. Tube distortion is yet another story for a different time (and a different guy as I'm a trumpeter not guitarist). Shannon Nyquist made the leap that since frequency response can be assured - that no quality is lost. Shannon Nyquist was incomplete. You need amplitude response too. The reason a ride cymbal sounds so damn good on a 5 watt mono Single Ended tube hifi... old enough to draw a pension... isn't because of the "great" frequency response on the unit.. the frequency response sucks on most of those old radios and reel2reels and record players (at least it does on mine). The reason is because the amplitudes of the frequencies it CAN do are turning on a dime and in the correct quantities. You can hear the millisecond the stick hits the ride on an old tube amp with shitty stock speaker. It isn't some muddy fuzz or some 808 sample, the hit is very well detailed. You can almost tell the weight of the stick. If you listen to a live recording, you hear the room noise as though you are actually there. Or, put differently for the guitar players out there... a guitar solo sounds like the players tube amp is right in front of you... because effectively... it is... What has worked well for me is to pair my tube hifi with a modern boombox. The boombox handles the lows and the tweeter stuff, which are low information frequencies. You don't hear the shoes the drummer is wearing in the subwoofer or the tweeter, but you might hear it in some well delivered mids.. as he shuffles across the floor. Under 100hz and over 10khz is all bout feeling the space of the music. Thats the stuff that makes it sound big and fat but the mids is where all the information is. The hifi does the telling, the solid state boombox does the selling. I balance levels and eq so the hifi can output the sweetest spot possible and then add volume and frequency range with the solid state side. From there, the volume level on the laptop acts as global volume. I mean ideally there would be a Single Ended amp and high sensitivity speakers and a high power push/pull with electrostatics to fill it out and some high end subwoofer to cap it off and I would have a re-purposed cathedral as my bat cave... but you work with the budget that you have...

[@sammys7518]

SETs have many inherent flaws. It is only because very very few understand how to design a top notch PP amp that SETs even exist. An excellent PP design will hands down beat an SET design. But PP are very difficult to design. Sad.

[@jatza07]

So basically what I lose when I drive low efficient speakers (87db) with class A tube amp ? To my ears my RH84 sounds really nice but all this discussion makes me fell like I miss something with the sound, the power is sufficient.

[@graemehumfrey9700]

Superb explanations

[@sammys7518]

Very poor and incorrect explanations. What he describes with the visual notch is Class B, Not Class AB1. This is first semester Electronics Engineering. The signal is also not taken apart and put back together. The information is almost totally useless.

[@oturgator]

Ummm... actually tube amplifiers in general Current Sources and modern Solid State amplifiers behave more like ideal Voltage Sources. The main difference between them being the Damping Factor. Even with low power ratings, the tube amplifier will have a higher voltage swing, making it sound louder than a SS amplifier of higher power output. When “the magic” kicks in, well that happens when a low Qes speaker like Lowther, AER MK1, Foster FE-206E meets with a Current Source amplifier. There is a considerable low frequency boost. Please find and read articles from Bob Carver and specially the famous PDF from Nelson Pass on current vs voltage sources.

[@sammys7518]

The damping factor of an SET amplifier varies not only along the musical signal waveform, but is also power output sensitive. The boost is almost assuredly distortion. There always seems to be a gimmick. Personally, I like live music better than artificially flavored music.

[@sammys7518]

The author's explanation of Push Pull operation has very little accuracy. The author's description with the left side photo notch, the scope sine wave at 6:58,, and signal split in half comment is Class B mode "50% duty cycle", nothing to do with Class AB1. In fact, Class AB1 has both output tubes running Class A, or 100% of the waveform for multiple watts output by definition. This is first semester Electronics Engineering. That is good for 80s/90s db spl. As the wattage rises, the output gradually slides into Class AB1 operation. There is no taking the signal apart and putting it back together. A completely false statement. Frankly, the video explanation is disgusting to me. As far as pure sound, well............. An SET amplifier has several inherent major problems that degrade the sound. One being the speaker sees a constant varying output impedance over the waveform, thus constant varying damping factor. Another is that there is not cancelling out of the 120hz ripple that PP has. This almost necessitates the need for inductors/chokes in the power supply filtering. A choke/inductor causes non distortion of the music. Another is the extremely high signal drive needed for many DHT tubes. The problem is the driver creates high harmonic distortion. Combine the harmonic distortions of each stage and suddenly one has higher orders. Many designs create very high amounts of 2nd harmonics to mask the negative effects. Interestingly, he mentions the black between the notes. Nothing there. With an elite PP amplifier and entire system, one would be hearing the reflections off the recording studio walls. Truly, one hears all the music, not just a portion with the inner detail blacked out. The good amps use no global negative and minimum single stage feedback. The main problem is that virtually no one understands what is involved and/or how to design a Push Pull amplifier. Oh, they know a few equations but not a true understanding. Lastly, if musical accuracy is one's goal, or gimmicks to manipulate the recording to one's own tastes. I could go on and on but won't.

[@victorbrantsen8872]

Great,again, thank you for not going too much into this debate, people get so polarised on this, sometimes. I love the SET sound, and let’s just say; it’ personal, just go out and listen, compare, and steer your own course. BTW, on the effiency part; My 845’s handle the Magnepans 3.3 R with no problem at all..! 2; What is your great intro blues music? Thanks again, victor from Holland.

[@biketech60]

YES ! Plus most SET amps also have no negative feedback . Feedback robs music of it's liveliness . It is almost always used in complex amplifiers to lower the measured distortion , which is always good for a company's marketing department .

[@D.E.E.P.Y.]

Combination on 300B + 805 (with grid cap) tubes gives me 50W per channel and serves as a heater with 450W power consumption 😂

[@jukingeo]

That is the problem with wanting higher power with SET tube designs. Once you get over 20 watts, the designs get complicated and they are extremely inefficient, consume power and expend most of it as heat. The rule of thumb with SET is to nix the inefficient speakers for more efficient ones. It is like the OP said above, try and get the SPL 1w/1m rating over 95 db, then you don't need such a big amplifier.

[@larryshaver3568]

are 6bq6's a triode or pentode

[@garymoore3497]

there is no switching cross over distortion inside a vacuum tube.

[@amdenis]

One thing, there are SET amps that are 200 Watts+. In fact, there are plenty of SET around the 100-300 watt range. I have a 75 Watt and a 200 Watt currently (Jackson Ampworks 75 watt) and a Valve Amplifier dual 3100 (dual mono 100 watt / stereo 200 Watt) - both SET. I had a Kraft 300, which was a 250 Watt pure CA amp, but that one I used for music listening.

[@basspig]

The notion of crossover distortion is outdated. Designs have improved to the point where this distortion is eliminated. People are shortchanged by the reduced performance of SETs.

[@sammys7518]

Nice to see someone who understands. Just to add, the crossover distortion mentioned is due to being operated Class B, not Class AB1. SETs are only used because very very few understand how to properly design PP Class AB1. PP Class AB1 actually operates Class A for several watts output until the tubes slide into AB1. Damping factor is basically constant vs SET with wildly varying damping factor/output impedance. SETs basically lessen the bass and highs, up the 2nd order harmonic distortion, and "magic" midrange.

[@basspig]

@@sammys7518 Being in the repair industry, I get to sample a wide variety of amplifiers of all ages and topologies and capture data with distortion analyzers. I frequently check down to the 1mW range to see if there is a rise in distortion. Rarely do I encounter such a rise. Folks don't realize that modern transistor amplifiers run in class A for small signal levels, where we are most sensitive to intermodulation distortion. Notch distortion is particularly nasty, because it worsens as signal level decreases and is heard as a constant grunge of harmonic hash artifacts. Push-pull Tube amplifiers have this issue at large signal levels. When a tube is biased so that small signal notch is not visible, and the test signal is increased to near clipping, many tube amps will start to notch due to insufficient plate current. I developed a signal responsive dynamic bias system some years back that uses some of the signal voltage to forward bias the tubes through a mix network. It is with this that I have have tube idle currents as low as 12mA, while still maintaining low distortion across the power output range. Idle bias might be -88V but decrease to -30V at full output. The complexity of the circuit involves making it track properly so there aren't bumps in the distortion vs power curve.

[@sammys7518]

@@basspig Nice explanation. A lot depends upon the design of the PP amplifier output stage, ps supply. I have never had a notch problem even though I idle near 65-70ma. I have used my Tek dual trace to check it out. Your idea of forward bias is interesting. I believe Carver entertained that design as well? cheers

[@basspig]

@@sammys7518 it is a function of the load line and the relationship between screen voltage and plate current. Depending on those relationships, an amplifier may be more or less sensitive to notching at high power levels. I have not seen a similar circuit in any of Bob Carver's amplifiers. He did employ some protection circuits on some models, but bias was pretty conventional on the ones I worked on.

[@sammys7518]

@@basspig In triode mode, there should not be any problem. I have no notch distortion at all in my PP circuit. How are you biasing your output tubes?

[@larryshaver3568]

Magnavox made an amplifier with a 12AX& and 2 50EH5's and it sounds mazing.it IS stereo

[@redstarwraith]

Thank you for this. I finally have a basic understanding!

[@sammys7518]

Actually you have been fed incorrect nonsense.. See above responses.

[@sambaron1319]

What about the fact that they do not have global negative feedback? Personally I noticed that local N.F. is harmless and actually, benefice. But global one is best to be avoid.

[@harbselectronicslab3551]

I equate the magic as a kind of performance resonance between the Amp and the Speaker........in simple terms, the speaker seems happier to reproduce what the amp is happy to produce......like an audio tracking tuned circuit almost

[@user-fp1iu4pi2c]

What is the song in the video?

[@geralddietz4577]

I have a M.A.G.I. ( massachusetts audio group ink ) flea amp 2.5 watts + - pushing klipsch forte' ones , magic .

[@larryshaver3568]

i meant 6bq5

[@franciscopelayo1648]

So that's what your face looks like. Cool video!

[@boonedockjourneyman7979]

Check out neutral linguistic programming. The magic may be related to the brain’s hypersensitivity to discordant sound.

[@eggsmann594]

I don't trust the industry db ratings for multi speakers :(

[@jermcrow3408]

Magic indeed!

[@sammys7518]

Cut the bass and highs and I can also attain midrange "magic" as well.

[@thelastofthedinosaurs]

You really need 95db? Audio Notes are like 93,5 db and works easily.

[@Blueglow]

@@thelastofthedinosaurs 93.5 is fine. Just not 89 or 90. You will burn up all the little power you have in the speaker coils and lose a lot before it gets to your ears. 98 plus is best.

[@thelastofthedinosaurs]

​@@BlueglowFezz makes parallel Single Ended 300B with 15 Watt. That should be enough.

[@tyeadel]

Push pull class A does not have crossover distortion; this applies to tube and transistor amplifier. Using push pull eliminates even harmonic distortion. Push pull can be class A, AB etc. Your description is of push pull is incorrect. Resorting to "magic" to describe SE!!!!

[@Spentelectrons]

From a guitar amplifier standpoint, in reguard to magic in fewer components, each component has a greater effect on the sound. Your not modifying a circuit to improve the sound. You can modify a single component.

[@Axman66]

thank you so much +++ now i know why there is a magic +++

[@sammys7518]

PP is clearly superior but very very few understand how to design it. Otherwise, SETs would become extinct. The explanation is nonsense.

[@salmonline]

"you see them being *run" not ran. ask your mom...lol...

[@ericjensen9091]

Thank you.

If THAT'S what you got out of this, then you might as well untwist your panties and go play outside.

[@guidoroemer81]

Ah, set amps. Those with 5 to 10% THD. Square waves that look more like sine waves. Low output asks for horn loaded speakers that add even more distortion. High efficiency speakers that also amplify the relative high hum and noise output of those amps. A biased video.

[@frankgeeraerts6243]

4 : Output transformers are biased into the hysterisis cycle .............So they pass very LOW level information and micro-dynamics !!!!!!!!! 5 / One can benefit from the very best Output transformes ( at a price ) ......permalloy and nanocrystaline technology..........incomparable quality compared with iron /silicium ones ....... 5 : Comonents will reveal their sonic texture , so synergy can be searched between tubes, resistors and capacitors ....... 6 : NFB is not necessary as correction ............processing only serves test gear but not the soul of the music .

[@sammys7518]

That sounds just like PP (except for the SET output transformers which need all the help they can get.) But so many inherent problems with SETs that cause distortion, of which there are at least 6 different types. PP can be designed totally accurate, SETs cannot. NFB not needed either.

[@mosfet500]

@@sammys7518 I like distortion, especially second harmonic. Undistorted amps are boring, Nelson Pass proved that in listening tests, he contoured distortion to please listeners. That's why there are people who love his amps. All tube preamps don't have to be class A, you could design a tube preamp that is PP if you wanted.

[@sammys7518]

@@mosfet500 A single Class A stage line preamplifier can be perfectly accurate, so no need to try PP. If it is boring, then one of two scenarios exist. 1. You do not like accurate, live instruments & voices. That is a personal choice. 2. Your stereo system is not accurate as claimed. So distortion might help. But that is a failure of the one or probably all the components in the system. 3. As far as 2nd order, negatively affects dynamics. If the system sounds scratchy, poor quality parts is probably the problem. 4. An SET amp has numerous inherent problems. As far as Nelson Pass, I have yet to find a SS amplifier of any brand that is actually accurate. Solid State has inherent problems/weakness which does not allow for accurate reproduction. This is via specialized listening testing procedures, not simple auditions. I have only found one tube amplifier that is truly accurate, and it is Push Pull. It takes one a whole step and beyond in sound quality. Unfortunately, the company no longer exists, retired some years ago. I prefer accurate because I like live sounding instruments. Again personal choice. cheers

[@mosfet500]

@@sammys7518 That's not what you said, you can have a PP preamp, the benefits are a non sequitur. Why can't you like both? No, people like distortion, that's why many people like the way tubes clip. Scratchy has nothing to do with it, neither does the quality of the parts. Every design has problems, there's no perfect design, it's tradeoffs regardless whether you're designing a car or an amp. Amps distort, speakers distort, rooms distort, DACs distort, and on and on. What's your point? Accuracy and musicality are two different things. Audio is like a photograph, if all you want to do is look at El Capitan as it exists then drive out and see it. Ansel Adams took exquisite pictures of El Capitan, you can see the majestic beauty of it but it's a picture. If you want to hear the Berlin Philharmonic unaltered go listen to it, if you buy a CD or record they are highly processed regardless whether the amp is sonically accurate or not, you're getting the sound engineers manipulation. They manipulate it and I manipulate it. If I buy an Arbitrary Waveform Generator, I want it to be accurate as possible, it has different design criteria and a different function. Guitar players like tube amps because of the distortion. Period. If you go to a concert that's live then there's no amplification, that's a limited experience, most singers and instruments go through amplification. There's a pleasure in listening at home to recorded music, that's what home audio is about, so why are you even hear? Trying to impress people with your understanding of electronics? Not impressed!

[@sammys7518]

@@mosfet500 If you like it, so be it. But a pre with distortion is not the reference. It also tells me that there is something else wrong with your system, unless you do not like live instruments. If you don't that is your choice. But don't later tell me that SETs are the holy grail, cause they don't make the standard. I depart in peace. Cheers