Which OpAmp is Better for 20W Class A Amplifier - OPA2604 vs NE5532? 

Hope you enjoyed it! Thanks for the feedback!

Thanks for sharing!

Thank you!

Thank you Tony! Cheers!

Thank you!

Thanks Keith. LOL, I think you are so right;)

It is still contained in the parts;) Thank you!

Great point - Thank you!

At room temperature....

@@KissAnalog hello, how about using RC4558? Or 4580 😂

Well in that case use LM741, they are probably free these days. The board is supposed to be hi-fi hopefully.

@@nicoras8803 Not worth to step down so much when you're professional engineer, but when you are getting your degree it's another story.

Thank you! I appreciate you! For those that want to squeak out every once of quality, the OPA604 or OPA2604 is a great part, but for the money - the NE5532 is pretty darn good too.

Thanks for the great feedback!

You are awesome! ;) Thank you!

Thanks Tron! Let us know how you like it if you do;)

also you can try TLE2082, AD825, burson v6 vivid, AD797

The exchange of NE5532 to OPA2604 only makes the difference in more output voltage swing due to power supply voltage increase from max +/-22V to +/-25 V. Relating most of the other parameters the OPA2604 is worser that the NE5532. Espacially it is 2 to 3 times more noisy especially in the lower frequency range between 10 Hz and 1 kHz. I'd personally prefer the NE5532.

Kala AD 823 bagai mana abang

Yes, BB was never a low cost company;) But, they are known and respected as top of the game. Thanks Ronnie!

Great feedback - thank you! I agree, if I were making this board I think I'd use actual linear regulators too. ;)

Great feedback - thank you!

Thanks for the great feedback! Swapping OpAmps for better sound is not usually beneficial - but in this case - it is for operating range. I need an OpAmp that can swing to higher voltage rails - so it is definately needed. Also, - just a btw - the NE5532 is used as it is a great 'low cost' OpAmp - and used because of this. There are better OpAmps for sure. ;)

Thanks for this feedback;) I would have to agree with you. I'll take more measurements at the final build. Let me know what you think;)

We know that JFETs have a quadratic relationship between input and output voltages, while BJTs have an exponential relationship. That implies a JFET will introduce principally second harmonic distortion, while a BJT will add odd harmonics. However, local negative feedback at each stage will reduce that distortion, and then the entire opamp will have overall negative feedback to set a fixed gain. For a TL072 with a gain-bandwidth product of 3MHz, it means that at 1Khz it has an available gain of 3,000. If you use it in a stage with a gain of 10, you're reducing the gain and hence the distortion by roughly 300 times. For an NE5532, it's 10MHz, and a reduction of 1,000 in a comparable setup. It's little wonder you can't hear (or see) the difference. FWIW, the LM4562 has a GBW product of 55MHz typical.

Thank you!

@@KissAnalog I’ve been using Sparkos discrete op amps in my Neve console - the op amps have duel compensation class A output current - most discrete op amps don’t sound at all like they are discrete instead sound like extra high frequency - but the sparkos have the class a sound when compared to a Neve 1073 class A pre amp 💯

Wow - thanks for the feedback! I will have to try the LM4562 OpAmps. Thanks for the tip!!

Hello Nico, I think you are the only one talking over the 3rd harmonic and its issues. If I may, and is is pertinent, here goes my5 cents of contribution to the topic. Hope we can chat about it. This is one of my fav. topics. The odd harmonics and its unfortunate presence in the modern music. Sound like a title doesnt it? But, if I mayh, lets brake it down. The 3rd harmonic are present in every instrument and mostly in the wind instruments (mainly in double reeds wind instruments) and yet those instruments sound realy good even when mixed up with a dense sprectrum. The Clarinet for g.e, mostly has odd harmonics. Also, lets remember that we are using the Equal Temperament System (Since BACH). The Equal temperament System has the perfect fifth wich is the 3rd natural harmonic. The problem is that when we use instruments tunned by fourths (like bass guitar, acoustic guitar and so...) we can not have the perfect tunning (dividing the octave by 12 perfect steps). The thirds will always sound a little bit off. Now imagine that you have a chord based on a triade (tonic, third and fifth). The fifth is the strongest harmonic on that chord and the fifth by itself also has the natural serie of harmonics. In a eletric guitar for example, the fifth harmonic of the fifth note of a Cmajor chord is an E, but the third note of a C major chord is also an E... but those E's aren't the same... the E note is alterated by the Equal Temperamented System, while the E harmonic is natural). Almost 99% that we can read about of harmonic distortion's sound quality is a misconception or a misuderstanding of the whole picture I would like to hear peoples opnion on this subject aswell. There is three books that I think is worth reading about this subject: 1- How Equal Temperament Ruined Harmony by Ross Duffin; 2 - The Physics of Musical Instruments - Fletcher 3 - Distortion. The cause of harmonics and the lie of THD - Dan Bullard

Great Feedback Nico! Thank you! I think this comment nailed it;)

Very interesting information here Eduardo! Thanks for sharing this! I think IMD type testing is done to be sure the input is reproduced accurately.

@@misterjorous I think you've misunderstood what second-harmonic and third-harmonic distortion are. If I play middle C (C4) at 256Hz, then its second harmonic is C5 at 512Hz (2 x 256Hz) and its third harmonic is G5 at 768 Hz (3 x 256Hz). We sometimes call these "overtones". You're talking about chords where a "third" is the note that is in a ratio of 5:4 with the fundamental like E4 (320Hz), and a "fifth" is in a ratio of 3:2 like G4 (384Hz). A clipped sine wave is equivalent to a mixture of the note and all of its odd harmonics in decreasing amplitude, and the ear is very sensitive to that, so we feel that as much worse distortion than second harmonic.

The odd harmonics are not really dissonant as the ear doesn't object to notes in a ratio of 3:1 or 5:1. The problem is that if we add a small amount of third harmonic to a pure sine wave, and then add a smaller amount of fifth harmonic, we start to create a wave that looks like a square wave, rather than a sine wave. That sounds like we've clipped or overdriven the original pure note and that's what our ears find harsh-sounding.

Thank you for that Tip and for his great feedback! Looks like another great option. It does have lower voltage rail specs but would be great for pre-amps or lower power amps;)

@@KissAnalog Early to mid-2000s, rolling opamps in a circuit was fashionable. Many headphone amp aficionados would build a "cmoy" headphone amp clone and with a socket, for the opamp(s) they would try different opamps and give their subjective opinions. So I wanted to try this on a Pioneer stereo amp and modified the preamp/tone control circuits with IC sockets to see if there is any truth to all of this. I felt that there is a difference in the sound signature of the opamps and if the circuit power supplies, decoupling, etc are good enough, the differences between opamp sound signatures are definitely audible. High-quality headphones, good jazz recordings can show the differences. See this link (not mine) if you are interested - tangentsoft.net/audio/opamps.html

Sadly the OPA2132 is about 10 times the cost of an NE5532 and still considerably more expensive than an LM4562. If you're not using a relatively high impedance source, I doubt they will ever have more than a subjective bias in favour of them.

I can't agree more - the filtering and support circuit around the chip can totally make a bigger difference.

That’s fantastic!

Thanks - that’s great! Let us know how it works out!

@@KissAnalog It s a servo op amp , it remove offset DC on the output of amplifier.

Yes, the BB part can operate at a higher voltage on the rails. I originally thought I'd try to get more power - and maybe I will;)

Thank you! I once started a design this way. I'll have to get back to that in another series down the road;)

Thank you for this! Great Point Michael! Maybe if it is pushed a bit above its power rating there will be less distortion. But then, unless I can raise the voltage rails on the OpAmp, the best reason is maybe to offer a JFET input;)

Thank you Jeff! I never heard of them before - always great to learn something new. From their spec, it looks like they are close to the NE5532. Both BiPolar and similar specs. Maybe easier to get real ones - maybe the Japan made parts are not intimidated?

You will have fun!

Thanks for the great feedback! I have the amp back and will do some testing!

Same OpAmp, distinct manufacturers.

@@misterjorous thank you!

Great answer #Eduardo Caetano;) Also, I think these OpAmps are so high level that they seem to work so great!

@@KissAnalog I love the 5532... perfect jellybean.

Thanks Eduardo! I agree - for the cost it is hard to beat! Especially when it takes one 4 or 5 times the cost to get something better - it it really is:)

Great question. In general - yes - but in my case I wanted the higher voltage rails.

@@KissAnalog Thank you! And will both stock and new opamp be in optimal regime of work then? Is trying to get some improvements of sound quality such way correct?

Thank you!! I can show why in science that the 5532 is not the best choice:P) What to you think of the OPA2604? Science would show that it should be better:)

Thanks for your feedback. There is nothing wrong with maximizing the voltage swing of you OpAmps. If you use OpAmps - you are trying to get away from the discrete circuits - so adding transistors to drive the signal doesn't make sense - if you can find a great OpAmp that can drive the signal from rail to rail. Sure- it is not a problem to use transistors - but now you have to make sure that they don't change your linearity.

There are many fakes but there are some reliable sources with real opa2604s but you can piggy back a pair of opa604s for the equivalent circiut and they are still in production. The opa2604 has dual opa604s in the same package. Browndog opamp adapters can be ordered with opa604s presoldered for around $18. I have found genuine opa2604s for $6 to $8. I have also some fake opa2604s. Be careful who you order from

Which is which? LOL thanks for your feedback. I'm still trying to find which is better;)

Great question! Yes - that is no problem for any OpAmp, but with what gain can it still do that - and how much noise? OpAmps are all pretty darn good - and some are just more exceptional.

@@KissAnalog thank you for the reply! The thing that confuses me is that according to the video link below its not flat from 20 to 20k . What's your thoughts on this? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-QCBUFBJh9bk.html

Thank you! And let us know if you make that video. It would be a great one;)

It is hard to tell, but they do look legit;) They have tested well so far.

@@KissAnalog Yeah it is hard to tell, and a lot of the time they test well. I have found the fake by looking at their leads. They always seem to look like they have solder on them and they seem to be made of a lower quality of metal i.e. very soft and bend very easily. If you have a real one next to a fake one you would see what I mean.

Thank you! I'll have a look at the leads of the new ones that I have. I could see that their process might not be as good...

Thanks Martin! Do you mean that so many amps out there have 5532s?

@@KissAnalog I was talking about studio desks/mixing. Great channel.

Thanks for the great feedback! Which OpAmp do you think is best for audio? How about with higher voltage rails?

@@KissAnalog it depends. For most of my audio amplifiers I use the NJM4562 because of its high slew rate, good linearity and low noise. For higher voltage rails (above 18 V) I use discret differential input stages

Who listens to sine waves, let alone square waves. You can calculate slew from frequency response.

@@nicoras8803 it's about waveshape rendering, overshoot, ringing etc... it could be triangle or whatever.. music with analog synths use all these waveforms. I cant believe old peoples still think they are not used in music haha it's used in more than 90% of modern music...you think you can test audio gear with AC/DC crapshit.. you could use bandlimited square wav to 25khz for example.. a system should reproduce it perfectly to be perfect.. note that you need an analog generator or a perfect digital to analog converter that also produce perfect square .. + a bandlimited square wave sample.. opamp datasheet have these and they are important in my opinion.. see sansui au-x1 amp for example on perfect square wav amplifier up to 90khz or so

@@lextr3110 I also do like to see the transisent response of a square wave on any audio path. A 100 pound drummer hiting a snare drum can not be replace by just a sinewave.

@@misterjorous they always have 1000 excuses not to test them ...

Thank you for bringing this up. I think it is a very interesting subject and question:) OK, so first I'd like to say @Nico Ras is right of course, you can verify rise time with bandwidth testing and vis a versa. You can't get a fast rise time if you have a low bandwidth. As for how an amp would respond to a specific rise time (suggesting it has the bandwidth to do it) is interesting thought. If it rings it would be thought to be bad, but in audio - is that true? First, if it is fast enough to rise and then free enough to ring - is that really a bad thing? If you then think about why a 'music' would have a square wave - which is not a natural wave, so it has to be synthesized, and is then can be formed by a compilation of sign waves. So if the amp does have a wide enough band width, yes it can do a square wave, but regarding to the stability or lack of - we are back to why a square wave would be injected into 'music'. That would sound like distortion (as it is not natural) so would ringing be bad - or is it just that it is not accurately reproducing this wave? So, another very important question is twofold, what frequency should this be done at - and what rise/fall time? Then comes, how much inductance/capacitance might there be at the output of the Amp? Great question - and this could lead to more videos;) One more thing that I eluded to above, if the amp is so well controlled that there is no ringing - does it sound that way - well controlled - or does it sound over-controlled? Just asking;)

Thanks - that's great info on how to tell a fake from the real deal;)

@@KissAnalog The easiest way to detect fake NE5532s is to measure the resistance across the two inputs with a multimeter in diode mode. A real NE5532 has back-to-back diodes as input protection and you'll spot the junctions in both directions. Of course, you might still get a real NE5532 which is a manufacturer's reject, so caveat emptor!

Great question! I am going to do a video where I compare several options. I’ll include a listening test as well;)

That's a great idea! Thank you!

@@KissAnalog welcome sir, Love from India

Tl072 better on dynamic side ....and for live instruments i found ne5532 ...what's your suggestion @ Kiss analog

I have received one in the post today. I will be testing them and listening to them on my channel soon. I think the main advantage is current availability, no advantage on a preamp circuit. Might help on headphones...we shall see.

@@MichaelBeeny I think you get less Eddy field current from each stage because of the distance interfering with each other and other interferences

Discrete is always fun - and it allows for tweaks and modifications. The OpAmp is petty amazing though - and probably hard to beat;) But, then there are the voltage limitations for higher Power Amps. Layout and routing are so critical - and this is taken care of where that art can easily be messed up;)

@@KissAnalog what even if you did it in micro-cap could mess it up

Great point @John Sweda. Micro-Cap can give a great place to add parasitics to see how things are affected.

Great advice. I was lucky earlier when I originally chose that OpAmp for this Amplifier. They were not cheep - except for that batch that came in huge qty. I thought the price was for a single part and expected a high price, so I didn't notice that they were sending multiple pieces for each item. When parts go in surplus they can be lower cost if they are not really an item that is in demand, but if they are like these OpAmps, you would expect to pay closer to $5 per unit. Which I did.

@@KissAnalog I've seen that opamp going for 14-15 bucks now! I was watching a comparison of 8 opamps recently. Honestly, Eddie, I can't hear much difference.

Thanks Jos! That’s a great part for lower power applications;) This kit seems solid. Good noise performance and ca handle the high (max) voltage. So hard to tell.

@@KissAnalog o yea you are right +/- 15v oke i did mis that ;-) , i did only build 1 opamp pre amp in my life, i now use a dac with a build in preamp, it sounds better than everything i did build ;-), i use a S.M.S.L SU8 for my setup, and it has a THD 0,0003%, so i can never build that, and its cheap yea i am dutch

Thanks and great feedback! This is a great topic! I was finally able to get 29 Watts out with the new OpAmps, so they were great to get the power (higher rail voltages). As for coloring the sound, the Class A and tube amps give even harmonics (distortion) as the BJT amps give odd harmonicsre right I think that people hear that as warmer. But using both Class A in preamp and amp stages doesn't multiply or enhance the warmer sound - it just keeps it the same. Mixing would provide both types of distortion and that is what people seem not to like.

Thanks Jeff for the feedback. I appreciate it. The ironic thing is this was a short video for me;) I am still always trying to get better. I have a tough time with my busy job and also doing this hobby (RU-vid), so it is hard to spend even more time producing these videos. I keep trying to make it a faster process-but it does just take time, but I'll keep trying. Maybe you will give it another chance in the future - to see if I have gotten better;)

@@KissAnalog You do have good topics and ideas. Keep it up.

Sorry about that.