As you may or may not have seen Jean Paul, I have a bit of an issue with the term 'digital amplifier' being used (lol, I see you have, your emoji tells me something ;P ), as its mostly used as a sort of woo woo marketing term written by the marketing department, with no regard for what digital means. I know you are a bit of an enthusiast of these type of amps and i'm in no way poo pooing their quality, its just the use of technical language that I have issue with. Digitally controlled amplifier? yes. Class D with digital front end? yes. Fully digital amplifier? no; not IMO. I hold a similar view to Bruno Putzeys on the matter and he explains it far better than I could. . a fully digital amplifier would amplify the code and the speaker and output filter would have to see and read/process that output signal as code. It isnt read as code, it is seen as a voltage (or current). the speaker has no knowledge or understanding of the meaning behind the signal; it is a dumb, analogue device. Whether the output COULD be read/processed as any PWM type hard switched signal could be read as code by the 'receiver' doesnt really matter; its whether it in fact is. In my (rather pedantic) view of it there are a whole bunch of other reasons too, but this is the main point for me; as it is what defines the term digital. I'm not sure how one could ever listen to a digital amplifier; unless we are living in the matrix.
You have a complex system with lots of balancing between fire and ice. If the KRC2 is anything like the KRC3 which i've owned, it errs on the side of dullness. The Utopias perhaps compensate this to an extent. The silver, especially in teflon, is not something i have ever been able to live with and i've tried many times. I even spend hours stripping teflon off OCC copper before using it
Such detailed context is sufficient to understand our different reactions to the 627.
It is not about the (indeed silly) name/form but about the added functionality that, of course, comes at a price. It's main drawbacks are that it is the end for DACs, opamp rolling and several hours trying out capacitors made of precious metals and best dielectric plastics let alone the painful loss of the pastime of trying out and talking/writing about all the stuff
Thanks for the explanation though, appreciated.
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Of course and in that I agree with you. I havent had the pleasure of owning any of the better 'digital amps', but the concept appears sound. I'm all for the digital process and run digital XO, but my amps are still of the more conventional type. I still run class AB (with the option of class A) (tweeters) Class AB (Mid-bass) Class AB (Subs) Dual 3 way amps, fully active setup, but the dac/dsp is separate.
Anyway I didnt want t divert the thread.
Anyway I didnt want t divert the thread.
Its always interesting to read other people's subjective assessment of op amps, especially when comparing the industry standards like NE5532, TL072, 4560 etc.
The one thing that is to understand here is how these chips are applied in the circuit ie. loading, hf compensation, gain, etc. The other problem is PCB layout, bypassing and PS decoupling. All those things are a great bit more influential on the "sound" and performance of the circuit than the chip itself.
The fact you favor the TL0XX series is an indication you prefer a generous portion of K2 HD. These bargain fet input chips are good at injecting that "sizzle" most vintage hifi ears like to hear. They do sound more engaging, but the odd order HD is too high for my tastes unless the application is specifically optimized to eek out the last bit of performance from it. Looking at the NE5532/34, these are really optimized for low imoedance sources and tend to sound lifeless if you have a more vintage audio type of sound preference. In fact, the original signetics/philips NE5532 and 34 are really great chips. They're used in so many higher end recording consoles (as are some TL0XX and LF3XX in specific stages), but there are also many other pieces of the signal chain that add flavor ie. coupling transformers, caps, etc.
The reason i mentioned Signetjcs and Philips is the fact that most of the newer copies of the NE series of amps are not as good as the originals. Also, there is a definitive difference in noise as well. I found this out by accident when I restored an old Revox CD player and noticed it sounded significantly worse than before, even with all the tried and true recipe of parts otherwise used and a long break in period. I replaced the IV op amps in this player because one channel had intermittent issues. I had to use JRC equivalent NE5532 to replace the Fairchild branded op amps, so i decided to go with my gut instinct and pull some Philips NE5532s from a parts unit to use instead - the magic sound was back and better than ever, just because of the otherwise equivalent generic op amps I substituted.
I got my hands on some NOS mil spec ceramic case NE5532s and have used them in upgrades of my personal gear. They have about the same character as the original Philips chips but sound a bit more transparent and refined to my ears. That being said, the original NE5532/ 34s overall sound balanced and have the "correct" sound. Used correctly, they have clean analytical tight low end, neutral mids and transparent quiet top end. Piano music is my go to benchmark test for evaluating audio gear and these original spec NEs have the most inert sound of any older bipolar op amp. I do prefer the "AN" spec for phono riaa stages because of the lower noise spec than the common N suffix. The standard version is more than up to the task compared to any of the other cookie cutter bipolar op amps. I've had good luck with the TI version AN suffix as well, but they do tend to be a little more forward sounding than the originals in lower gain situations, so I understand why you would label them as shouty. By far the nastiest bipolar op amps are the 4556, 4558 and LM324. They sound downright awful and usually are found in cheaper gear that have tons of polarized electrolytic and mylar coupling caps in the signal path. Alot of budget "DJ" / karaoke mixers and amps come with bucket loads of these nasty chips.
Regarding the TL chips, I really don't like them, mainly because they sound veiled. The grainy treble along with the looser bass is just too heavily flavored for me. The OPA2604 and 2132 are a bit better but still sound blurred and colored compared to a good old NE5532. I've tried many other op amps in various circuits and always come back to the NE 5532 / 34, simply because it just does almost everything right. Ive also used the LM4562 but it has a thin sounding bottom end compared to the other bipolar chips. It does however have very low noise and lower internal offset so that's one thing going for it. In general, I would only use the TL chips in typical utilitarian applications like in DC servos or meter drivers and that's really all they're good for. There are some other very nice sounding fet input op amps like the AD8066 (optimized for higher bandwidth video), but these chips are generally fussy and hard to implement correctly, so that you don't run into stability issues - trying to use them in older audio gear with sub optimal PCB layouts isn't going to work in most cases thanks to the higher bandwidth capability.
IMO, most of the time you can get bigger improvements just from decoupling the op amp supply pins with the right type of capacitors, optimizing the ground plane, matching L/R ch gain setting resistors and swapping cheap electrolytic caps in the signal path with higher grade ones. More often than not, if you hear in improvement just from swapping like components, its due to inadvertently fixing or optimizing a poorly engineered part of the circuit design itself.
The one thing that is to understand here is how these chips are applied in the circuit ie. loading, hf compensation, gain, etc. The other problem is PCB layout, bypassing and PS decoupling. All those things are a great bit more influential on the "sound" and performance of the circuit than the chip itself.
The fact you favor the TL0XX series is an indication you prefer a generous portion of K2 HD. These bargain fet input chips are good at injecting that "sizzle" most vintage hifi ears like to hear. They do sound more engaging, but the odd order HD is too high for my tastes unless the application is specifically optimized to eek out the last bit of performance from it. Looking at the NE5532/34, these are really optimized for low imoedance sources and tend to sound lifeless if you have a more vintage audio type of sound preference. In fact, the original signetics/philips NE5532 and 34 are really great chips. They're used in so many higher end recording consoles (as are some TL0XX and LF3XX in specific stages), but there are also many other pieces of the signal chain that add flavor ie. coupling transformers, caps, etc.
The reason i mentioned Signetjcs and Philips is the fact that most of the newer copies of the NE series of amps are not as good as the originals. Also, there is a definitive difference in noise as well. I found this out by accident when I restored an old Revox CD player and noticed it sounded significantly worse than before, even with all the tried and true recipe of parts otherwise used and a long break in period. I replaced the IV op amps in this player because one channel had intermittent issues. I had to use JRC equivalent NE5532 to replace the Fairchild branded op amps, so i decided to go with my gut instinct and pull some Philips NE5532s from a parts unit to use instead - the magic sound was back and better than ever, just because of the otherwise equivalent generic op amps I substituted.
I got my hands on some NOS mil spec ceramic case NE5532s and have used them in upgrades of my personal gear. They have about the same character as the original Philips chips but sound a bit more transparent and refined to my ears. That being said, the original NE5532/ 34s overall sound balanced and have the "correct" sound. Used correctly, they have clean analytical tight low end, neutral mids and transparent quiet top end. Piano music is my go to benchmark test for evaluating audio gear and these original spec NEs have the most inert sound of any older bipolar op amp. I do prefer the "AN" spec for phono riaa stages because of the lower noise spec than the common N suffix. The standard version is more than up to the task compared to any of the other cookie cutter bipolar op amps. I've had good luck with the TI version AN suffix as well, but they do tend to be a little more forward sounding than the originals in lower gain situations, so I understand why you would label them as shouty. By far the nastiest bipolar op amps are the 4556, 4558 and LM324. They sound downright awful and usually are found in cheaper gear that have tons of polarized electrolytic and mylar coupling caps in the signal path. Alot of budget "DJ" / karaoke mixers and amps come with bucket loads of these nasty chips.
Regarding the TL chips, I really don't like them, mainly because they sound veiled. The grainy treble along with the looser bass is just too heavily flavored for me. The OPA2604 and 2132 are a bit better but still sound blurred and colored compared to a good old NE5532. I've tried many other op amps in various circuits and always come back to the NE 5532 / 34, simply because it just does almost everything right. Ive also used the LM4562 but it has a thin sounding bottom end compared to the other bipolar chips. It does however have very low noise and lower internal offset so that's one thing going for it. In general, I would only use the TL chips in typical utilitarian applications like in DC servos or meter drivers and that's really all they're good for. There are some other very nice sounding fet input op amps like the AD8066 (optimized for higher bandwidth video), but these chips are generally fussy and hard to implement correctly, so that you don't run into stability issues - trying to use them in older audio gear with sub optimal PCB layouts isn't going to work in most cases thanks to the higher bandwidth capability.
IMO, most of the time you can get bigger improvements just from decoupling the op amp supply pins with the right type of capacitors, optimizing the ground plane, matching L/R ch gain setting resistors and swapping cheap electrolytic caps in the signal path with higher grade ones. More often than not, if you hear in improvement just from swapping like components, its due to inadvertently fixing or optimizing a poorly engineered part of the circuit design itself.
profiguy, thanks for taking time with that thoughtful response
I also have a soft spot for the TL072 because of mr finnegan and the klon, but even with the clipping diodes out "grainy" is definitely right for that pedal. (I realize 9v guitar overdrives VS hifi preamps are apples and oranges)
- I think you're probably right about my preferences. I also like horn speakers, so sizzle / bark/ etc is in my wheelhouse.
- other folks in this thread have said the same thing about the phillips 5534's sounding better. I would definitely be interested in trying out a set against the TI ones I have. I believe you may be correct
- Regarding design and layout, thanks for providing specific examples of how to adjust design elements instead of saying "better designs will be reflected". Useful stuff.
I also have a soft spot for the TL072 because of mr finnegan and the klon, but even with the clipping diodes out "grainy" is definitely right for that pedal. (I realize 9v guitar overdrives VS hifi preamps are apples and oranges)
I heard something similar in 1985 after replacing a blown Signetics 5534 (one out of 6 in a phono) with a Ti. The two channels sounded completely different after the change. The Ti had slightly better highs but everything else and bass in particular was much worse. These opamps were only listenable in the inverting topology anyway.
The KRC2 is a class A design, known for it's smoothness detail and neutrality. (If you found the KRC3 dull I would look to other components in the setup). Most (me also) tell that silver cables can be bright, with class AB gear certainly so, but that's just in our view (after trying many exotic types) because they take no prisoners and are faithful, in the wrong system they can be very unforgiving though. The mezzo's in fact have a strident top also, that's why I put Teflon caps in, just as with silver mica tiny value caps, there's nothing like them in my view. Teflon for cable insulators make little if any difference I've found, air is a good insulator! it's the silver that does the job. But as I said it's all subjective, I suppose that's why people do double blind testing to make sense of it all. All the best, enjoy your gear.You have a complex system with lots of balancing between fire and ice. If the KRC2 is anything like the KRC3 which i've owned, it errs on the side of dullness. The Utopias perhaps compensate this to an extent. The silver, especially in teflon, is not something i have ever been able to live with and i've tried many times. I even spend hours stripping teflon off OCC copper before using it
Such detailed context is sufficient to understand our different reactions to the 627.
As I said, the problem is most of the Sig/Philips 5534/2 on Ebay are fake. You may want to try to find real one in some broken old equipments. There are usually socketed. If someone has real ones, I'll buy them. They are valuable.
Yes, that's true about the counterfeit garbage found on ebay. Most are remarked 4558s. You can usually tell by the font and the faked lot number that never changes. The ones in the picture are the real deal ceramic body version and very hard to come by. I found them at a yard sale in my area - go figure.
I'm not sure why there is such a big spread in quality among 5532 / 34s. The dye will certainly be different because from personal experience I can run these FE spec 5532s on up to 20V rails without issue (+/- 18V is rated max spec). I torture tested one into a 100R load at +/- 22V rails for a whole week without issue. It actually got pretty warm but never showed any other symptoms of stress. Two of these with each internal pair in parallel and SE push/pull on a single rail per channel makes for an amazing higher impedance HP amp. I tried a few others under these conditions and most failed within a minute or two, with the exception of the TI branded "AN" version and the NJM branded "N". Of the two, the NJM sounds closest to the old Signetics version, but a hint more noisy.
@analog_sa - I can agree with you regarding the inverted topology being more listenable in a higher gain application. Thats usually why most RIAA is done this way with op amps.
@Salas - They were originally NE5532Ns running inverted and another one behind doing LP and de-emphasis. The TIs I tried sounded like plastic with both top and bottom missing. I was shocked at how bad it was, but chalked it up at first to other caps replaced needing break in. This was with the an S1 TDA1541A dac which is my all time favorite converter when running in NOS mode. The signetics NEs also had much lower offset than the TIs, closer to the converter's own 2mA. All I can say is these replacement spec NE chips are all over the map with internal specs ie. offset, noise and open loop thd/gain. The TIs need 22pf bypass in unity gain mode and good decoupling. I can run the signetics without any decoupling wide open into 600R without any overshoot on the output or other signs of instability, although its stupid to do.
@asilker - The TL op amps really are better for single ended low voltage rails and do very well in stomp boxes and active guitar preamps. I tried so many other ICs in my active bass preamps and the TL072 just sounded the best, especially in my music man bass with 18V power. The TL062 gave better battery life but sounded thin and brittle compared to the TL072. The TL082 was even worse and pulled alot of juice on top of it. The LF356 isn't that bad either in a preamp but the OPA2604 was the winner despite 20mA idle at 18V - now thats a battery killer.
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LOL !!! this was a fun read and interesting outcome
Interesting though because I have done personal opamp test and surprising that the TL072 regardless of " specs" on paper
always had a certain magic and fail proof result. Maybe everyone has a favorite transistor or Opamp from early days of learning.
Not only did the TL0 series pass listening /design test it was the first opamp I played with.
Specially with single supply designs. Always wins
Even if I spilled a cocktail and wet myself, angry or happy the 5534 would still annoy me.
Growing up around live audio equipment/mixes/ processors etc etc
From affordable to some ridiculous priced equipment.
Most are full of TL072 or 74
And any old school MI ( musical Instrument) Engineer will usually go straight to those OpAmps
Many new designs still use them. And plenty instantly roll their eyes when a 5534 gets mentioned.
Or roll their eyes when people " upgrade" opamps in cheap MI amplifiers or effects.
I believe the issue with the subjective differences heard between the jfet and bipolar op amp types are due to the distribution of distortion components throughout the entire audio spectrum combined with the magnification of these artifacts by fewer, higher gain stages and high efficieny speaker drivers.
The two types of op amps have different sound signatures for sure, but how much of this difference you can hear varies because of many factors, including the theory mentioned above but also from how optimal (or less than optimal) the op amp is implemented into the circuit. Jfet op amps are rather forgiving in terms of input bias offsets, source impedance mismatch, hf gain compensation, etc. Its really hard ro get them to misbehave if you follow some basic design rules. Most common pro audio and musical instrument gear uses them due to their inherent high input impedance and ease of interface with all sorts of sources, being more forgiving and versatile all around. I've built alot of specialty one off pedals for myself and others using TL and LF series op amps and they're a blast to design with. You dont really need to pay much attention to decouoling the supply rails or the like. A few 100nF ceramics here and there are all you need for rock solid operational stability.
Bipolar input op amps on the other hand can be difficult to implement correctly to get true high end, low noise and high fidelity performance out of them, especially the really high bandwidth types that demand RF circuit design and PCB layout rules to perform at their best with a safe margin of stability. The NE5532 / 34 are just 10 MHz devices, but thats 3 times the bandwidth of the budget TL or LF series stuff. The NE chips were designed for use in audio and they still shine when used correctly. The key here is correctly. That being said, if you're really careful and pay close attention to your design, PCB layout, etc you can get some nice results from those lowly jfet chips that can walk all over an average design that uses NE chips. I cant emphasize how important the circuit design around the chip is.
in general, I don't want any op amps in the direct signal path of my amplification stages. They're howeevr unavoidable in most source gear and that is usually where I focus my work. Unlike other supporters of the budget jfet chips, I really dont enjoy the sound signature of them and can usually tell their presence. There have been a few exceptions, but the sound is usually noisy, sizzly top end with an artificially wide sound stage. Add to that a scooped out midrange and bloated low end. Many people like this sound and thats cool, but I don't.
This isn't meant to sound arrogant or boasting, but I have worked on, with and custom modded alot of high end pro studio gear, including large format vintage consoles, analog and digital open reel tape machines, record cutting lathes, microphones, etc along with tons of all types of rack gear and some of the most exclusive high end audio gear that I could only dream of affording. I have personally worked with a broad spectrum of gear and designed expensive systems for live venues and clubs, mostly in Europe back in the late 70s and 80s. I know what's used in this stuff and can hear the differences between it all based on the parts and how they're applied, so i always try to make note of how something sounds based on its internal design. I'm not one of those guys who buys 500 dollar preamp tubes and spends a month listening to them through 2000 dollar interconmects. I dont have the time, money or patience for that. I just want to hear great music played back properly and learn as much as I can while doing so. The learning process never stops up until your eyes close for last time when you take your final breath. I also like to share what I learn with others, especially the younger mp3 generation and because of my efforts, hopefully some of them will have the chance to hear uncompressed music played back properly on a good audio system.
The two types of op amps have different sound signatures for sure, but how much of this difference you can hear varies because of many factors, including the theory mentioned above but also from how optimal (or less than optimal) the op amp is implemented into the circuit. Jfet op amps are rather forgiving in terms of input bias offsets, source impedance mismatch, hf gain compensation, etc. Its really hard ro get them to misbehave if you follow some basic design rules. Most common pro audio and musical instrument gear uses them due to their inherent high input impedance and ease of interface with all sorts of sources, being more forgiving and versatile all around. I've built alot of specialty one off pedals for myself and others using TL and LF series op amps and they're a blast to design with. You dont really need to pay much attention to decouoling the supply rails or the like. A few 100nF ceramics here and there are all you need for rock solid operational stability.
Bipolar input op amps on the other hand can be difficult to implement correctly to get true high end, low noise and high fidelity performance out of them, especially the really high bandwidth types that demand RF circuit design and PCB layout rules to perform at their best with a safe margin of stability. The NE5532 / 34 are just 10 MHz devices, but thats 3 times the bandwidth of the budget TL or LF series stuff. The NE chips were designed for use in audio and they still shine when used correctly. The key here is correctly. That being said, if you're really careful and pay close attention to your design, PCB layout, etc you can get some nice results from those lowly jfet chips that can walk all over an average design that uses NE chips. I cant emphasize how important the circuit design around the chip is.
in general, I don't want any op amps in the direct signal path of my amplification stages. They're howeevr unavoidable in most source gear and that is usually where I focus my work. Unlike other supporters of the budget jfet chips, I really dont enjoy the sound signature of them and can usually tell their presence. There have been a few exceptions, but the sound is usually noisy, sizzly top end with an artificially wide sound stage. Add to that a scooped out midrange and bloated low end. Many people like this sound and thats cool, but I don't.
This isn't meant to sound arrogant or boasting, but I have worked on, with and custom modded alot of high end pro studio gear, including large format vintage consoles, analog and digital open reel tape machines, record cutting lathes, microphones, etc along with tons of all types of rack gear and some of the most exclusive high end audio gear that I could only dream of affording. I have personally worked with a broad spectrum of gear and designed expensive systems for live venues and clubs, mostly in Europe back in the late 70s and 80s. I know what's used in this stuff and can hear the differences between it all based on the parts and how they're applied, so i always try to make note of how something sounds based on its internal design. I'm not one of those guys who buys 500 dollar preamp tubes and spends a month listening to them through 2000 dollar interconmects. I dont have the time, money or patience for that. I just want to hear great music played back properly and learn as much as I can while doing so. The learning process never stops up until your eyes close for last time when you take your final breath. I also like to share what I learn with others, especially the younger mp3 generation and because of my efforts, hopefully some of them will have the chance to hear uncompressed music played back properly on a good audio system.
I wish I could drink... maybe then I could quit obsessing over that pesky 60 cycle hum buried in my pink noise at -130 dB and stop trying to decipher the lyrics to Suck My Kiss...
That song has a lot of basic meaning
which slightly changes from verse to verse.
Basically about a guy who loves his girl so much he would do anything for her.
But mentions the voices in his head saying. She is special unlike the many
"one nighters" in the past. And if she were to leave it would really hurt.
And speaks of cold stares you get, from other men being jealous
of how beautiful your girl is.
Then liking the fact, that even though its a deep romantic love.
Still likes the fact the girl can be kinky and random.
like the other one nighters.
The kinky quicky, one night girls dont hurt his feelings,
But the romantic long lasting love might not be kinky.
This one is romantic and kinky.
Suck my kiss is a reference to certain sexual act.
In the context of the song, the girl he is really in love with
will do this in public. Just like the other kinky ones that
have no meaning to him.
Oh boy,, I sincerely did not expect an explanation to that as I was trying to be a bit subversive and funny... lol. I do understand the premise of the song though. That album is a great piece of work. The production and recording are amazing while sounding very raw and overdriven. My favorite 90s rock album. Rick Rubin is a genius.
Actually, no, it is very seldom used in phono applications because of the high noise when tackling a 47k input impedance. In general inverted requires small resistor values which is again problematic as the 5534 does not sound very good in less than a few kiloohm. The only technical advantage of inverted is less common noise distortion.
I would happily trade extra noise for better sound, but most people, understandably, would not.
I was referring to MC input, sorry. I don't really use any MM these days so I sort of wrote them off. The <100R MC load works out well for having a separate 5534 do the buffer output after the passive network. I like the sound of this topology. The risk is harming the cart windings with input bias current if an xformer isn't used. I've done a discrete jfet diff input stage with passive RIAA behind and then buffered. I'll have to dig in my papers and see if I can find a good example.
The 5534 is very good at I/V conversion hence everyone tends to use it for that. My AT-OC9 sounds very clean yet warm with the 5534 input stage and passive riaa but I don't feel safe with it direct coupled without step up xformer. I took out my Benz Micro MC with a bad input stage, so I'm very cautious these days. Discrete jfet input pair is more open and resolving, plus its a safe interface to the MC.