Thanks abraxalito for your invaluable comments. There is no earthloop, hum or any other grounding issues as I've "star" grounding & all +/- pins are decoupled with 0.1uF polyester film caps. I've also incorporated an earth lift switch. Surprisingly there isn't any RF/EMI problems either despite I had reinstalled the preamp from dicast alu box to an ABS enclosure.
Yes,you're absolutely right in your assertion in using single supply, especially from an economical perspective. It's just that the pre doesn't sound "open" or"spacy" on 9v single supply. The difference is like night & day with +/- 9 (12 or 15v!)
You may agree that a sonically pure ic may not be as musical as a jellybean one with some specification deficiencies! JRC 4558 is a good example of this as the most sought after chip for Ibanez TS effects! This could be due to the fact that NE5532 too is nearly 30 yrs old & not as efficient as the modern chips yet highly musical in a particular application.
I will definitely try the LM6172...I actually considered it at one time,but decided against as it was rather pricy for my liking.
Yes,you're absolutely right in your assertion in using single supply, especially from an economical perspective. It's just that the pre doesn't sound "open" or"spacy" on 9v single supply. The difference is like night & day with +/- 9 (12 or 15v!)
You may agree that a sonically pure ic may not be as musical as a jellybean one with some specification deficiencies! JRC 4558 is a good example of this as the most sought after chip for Ibanez TS effects! This could be due to the fact that NE5532 too is nearly 30 yrs old & not as efficient as the modern chips yet highly musical in a particular application.
I will definitely try the LM6172...I actually considered it at one time,but decided against as it was rather pricy for my liking.
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I've found the traditional style of two 0.1uF caps from each rail to gnd at the chip problematic for SQ. I'm guessing this has to do with the supply rail HF hash getting on to the gnd. I prefer nowadays to have a series resistor with the caps - somewhere in the range 1-4R7 is typical. This attenuates HF hash on the local gnd because all gnd connections come with inductance. My other solution is going balanced whereby no current flows to gnd and therefore no decoupling needs to be to gnd.
Perhaps this is the 5532 not liking such low supplies - I don't know because I've never tried a 5532 at 9V.
Yes, its more expensive than 5532. Hard to find an opamp which isn't as the 5532 is such a great bargain.
@suntechnik - I've tried AD8065 which is the single version of AD8066. It adds a top end colouration which I don't care for. I got some really cheap but I doubt I'll use them much because of this. I'm not the only person who's noticed this colouration. On paper though it looks excellent.
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Well, you should read Dougles Self's (the famed Sound Craft & other mixer designer) very detailed technical report on OPA2134. Appararntly, according to Mr.Self's tests, has a very nasty distortion curve around & above 10kHz! On the other hand, NE5532 faired far better if not beat many of the newer chips on specs!
I've used OPA2134 as very high impedance input buffer, but found it a bit susceptible to short circuit & sudden power failure! I've indeed destroyed a few,but found OPA2132 more stable & better sounding!
Over the past several weeks I have been trying several opamps in my WM8740-based DAC and I will offer my impressions of them for this purpose:
1) OP275 - This is the opamp that was included with the DAC. Warm and smooth, but boringly so. Flat.
2) AD8599 - Generally good, with decent sound stage, but the top end is too hot and seems slightly distorted. Not "real" sounding.
3) OPA2132 - Very nice and well-balanced. Great bass. Warm, but not overly so. Slightly receded highs make for less forward sound and slightly narrower sound stage than AD8599, but still far more pleasurable to listen to.
4) OPA2107 - All the same great sound as the 2132, except the top end is better and the sound stage and imaging are improved. Perhaps slightly less bass? Either way, I really like this one. If I had not tried #5 below, this would be my opamp.
5) AD8066 - Thick, but fast bass. Incredible treble extension. Excellent mids. Sounds extremely accurate and fast. The sound stage and stereo separation seems twice as wide as any of the others and the imaging just blows my mind.
You can probably guess that the AD8066 is my current favourite. I generally like the "warmer Burr Brown sound", but I am running tube amplification, so I get plenty of warmth from that.
I find the combination of a fast, clean, crisp, accurate (analytical?) source with tube amplification and single-driver full range speakers to be very potent and impressive!
I may switch back to the OPA2107 and/or OPA2132 at some point just to hear the difference once again, but I think the AD8066 has found a permanent home in my DAC.
1) OP275 - This is the opamp that was included with the DAC. Warm and smooth, but boringly so. Flat.
2) AD8599 - Generally good, with decent sound stage, but the top end is too hot and seems slightly distorted. Not "real" sounding.
3) OPA2132 - Very nice and well-balanced. Great bass. Warm, but not overly so. Slightly receded highs make for less forward sound and slightly narrower sound stage than AD8599, but still far more pleasurable to listen to.
4) OPA2107 - All the same great sound as the 2132, except the top end is better and the sound stage and imaging are improved. Perhaps slightly less bass? Either way, I really like this one. If I had not tried #5 below, this would be my opamp.
5) AD8066 - Thick, but fast bass. Incredible treble extension. Excellent mids. Sounds extremely accurate and fast. The sound stage and stereo separation seems twice as wide as any of the others and the imaging just blows my mind.
You can probably guess that the AD8066 is my current favourite. I generally like the "warmer Burr Brown sound", but I am running tube amplification, so I get plenty of warmth from that.
I find the combination of a fast, clean, crisp, accurate (analytical?) source with tube amplification and single-driver full range speakers to be very potent and impressive!
I may switch back to the OPA2107 and/or OPA2132 at some point just to hear the difference once again, but I think the AD8066 has found a permanent home in my DAC.
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My question is are any of these test fair to the devices that are being tested here? What I mean by that statement is that if you are merely rolling opamps and not optimizing each one for the circuit in question is the test valid? From what I gather from my reading each opamp may operate optimally under slightly different conditions, voltage changes and such, along with any needed external decoupling capacitors and other factors may significantly change the characteristics of the opamp in question. So if each op was optimized and then subjectively compared the results could be very different.
Indeed. This is very true. However, not all of us have the knowledge or skills to optimize a circuit for each specific opamp. For those of us whose circuit is static (as purchased) all we can hope to do is roll through opamps till we find one that subjectively sounds best in that circuit.
This is why I stated my particular use of the opamp before my listening notes. It is only relevant to those people using the device in the same/similar manner, and then just barely so because it is subjective anyway.
To be clear, I certainly do not think any absolute statements can be made about an opamp other than what is stated in its spec sheet.
Despite all of this, I have noticed that each opamp does seem to have a general "flavour". It seems this way, at least, because there does seem to be some general consensus about the sound of some opamps. Most people agree, for instance, that OPAs are generally warmer than ADs, and that the OPA2132 sounds better than the OPA2134, etc. etc.
In the end it really is anecdotal evidence, but it is important. It was this kind of info that inspired me to try all of the opamps I did, and I am glad I did so.
cogitech,
At least that is a very honest answer. If we are only going off of subjective information then everyone would really have to make up their own mind as I doubt that many agree on what sounds best to them. When it comes down to circuit design then I would expect the designer to optimize each circuit for each device if an honest answer is really being looked for on a technical basis. For you you have found what you are looking for and that is fine. We just have to remember that in each situation with a different circuit topology the results can easily change.
At least that is a very honest answer. If we are only going off of subjective information then everyone would really have to make up their own mind as I doubt that many agree on what sounds best to them. When it comes down to circuit design then I would expect the designer to optimize each circuit for each device if an honest answer is really being looked for on a technical basis. For you you have found what you are looking for and that is fine. We just have to remember that in each situation with a different circuit topology the results can easily change.
There is no such thing like "optimizing a circuit for specific opamp". Opamp is a standard building block. Right opapmp has to be picked up for specific task that is true.
For example instrumental AD8620 data-sheet claims "APPLICATIONS: High performance audio" so there is nothing wrong in using AD8620 instead of NE.
suntechnik,
That would seem to go against some of what is in both the Bob Cordell and Doug Self books on design. Doug has a certain way that he parallels opamps to lower distortion rather than using higher cost opamps. So I do not think that the statement that all opamps that are called audio opamps says that they are all equivalent in use. There is more to it than the general case, there is also the specific construction and component design of each opamp that would need to be considered.
That would seem to go against some of what is in both the Bob Cordell and Doug Self books on design. Doug has a certain way that he parallels opamps to lower distortion rather than using higher cost opamps. So I do not think that the statement that all opamps that are called audio opamps says that they are all equivalent in use. There is more to it than the general case, there is also the specific construction and component design of each opamp that would need to be considered.
I think you need to brush up a little on this. Every op-amp has a few things that were optimized in place of others. Loading varies, compensation varies, drive capability, etc. Some like being pulled into class A, others don't. When they ever invent a perfect op-amp, then it will be a standard building block. Until then, they are a complex part just like every other.
Doug's paralleling op-amps is SOP. Works great, but SOP. He does admit the National is actually better overall then the 5534, but will still defend the lower noise of the Signetics. You do have to respect it when he reminds you, that wonderful CD you are listing to while evaluating all these new expensive op-amps has gone through hundreds of 5534's in the studio. He might have designed the board.
tvrgeek,
I have no iron in the fire as to which opamps sound better than others. I just objected to the statement that they were all interchangeable and could be substituted at will into any audio circuit. I am sure that you can hear a difference between models and even brands of the same type, and this is what you are getting at in your last comment on what is it that is making these differences. I would be interested in following that conversation rather than the statement that a particular opamp is superior to another just by rolling opamps in a particular circuit.
I have no iron in the fire as to which opamps sound better than others. I just objected to the statement that they were all interchangeable and could be substituted at will into any audio circuit. I am sure that you can hear a difference between models and even brands of the same type, and this is what you are getting at in your last comment on what is it that is making these differences. I would be interested in following that conversation rather than the statement that a particular opamp is superior to another just by rolling opamps in a particular circuit.
I'll leave the "why" up to you guys, as I really have no idea. All I know is that I can hear it. Same way I can hear the difference between various 12AU7s, 12AX7s and 12BH7s in my tube amp, or the difference between Electro-Harmonix EL34s and Shuguang Hi-Fi series EL34s ...
I see "slew rate" being referenced a lot by people who sound like they know why one opamp sounds different than another. I also get the impression that Burr Brown (now TI, of course) specifically makes their opamps "warmer", or more "analog sounding" in response to this idea that "digital sound" can be "harsh". But this is all just from opinions I have read on the many forums out there, so... big grain of salt.
I see "slew rate" being referenced a lot by people who sound like they know why one opamp sounds different than another. I also get the impression that Burr Brown (now TI, of course) specifically makes their opamps "warmer", or more "analog sounding" in response to this idea that "digital sound" can be "harsh". But this is all just from opinions I have read on the many forums out there, so... big grain of salt.
The thing is, if you put an OP275 in a circuit and let a group of people listen to it, then switch to a (more) modern AD opamp like AD8066, I believe the difference will be very noticeable to nearly anyone in the group, and I do not necessarily think the circuit would matter all that much, as both of the opamps are commonly used in various audio circuits to good effect (to the best of my knowledge).
Would the results change if you put the two opamps in their respective "ideal circuits". I don't know, but my gut says, "no, the AD would still sound better to most people."
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Doug claims BJTs quasi complementary no good. National Instruments implements NPN quasi complementary in LM3886.
Doug claims electrolytic more than adequate for audio freq however one can easily build simple SET 12AX7+EL84 and roll over decoupling cup in order to audition cups difference it's very prominent actually.
Well yes SOIC on dip browndog has to be handled with extra care like extra NPOs on IC power legs to ground.
And yes ultra wide BW opamps like AD8066 has no common sense for audio in general but AD8066 cheaper than instrumental AD8620
And yes ultra wide BW opamps like AD8066 has no common sense for audio in general but AD8066 cheaper than instrumental AD8620
...and, most importantly, I have found several (subjective) comparisons of these two opamps and the 8066 is usually preferred. Having said that, I have not tried the 8620. Perhaps I should.
Kin, We are on the same page with the interchangeability question.
Cog: Please be patient for a second. We want to help you with your "best of my knowledge" as we believe it could be expanded just a little.
I have no doubt just swapping chips may change the sound and a few people can hear the difference. I am sorry if you are cursed with hearing that good You are jumping to the conclusion it is the op-amp that is causing the change, not how the op-amp interacts in the circuit.
Hint: Undercompensate an amp, it may sound edgy. (at the limit, just oscillate or latch up) Overcompensate it it will be smooth but flat. I could easily see this in the wave forms of my Hafler 120 when I converted it from VAS loaded compensation to TM. A few puffs one way or the other made an audible difference.
Hint: Commonly used does not always relate to appropriate or optimal.
Hint: You are correct in "slew rate" is just a parameter. Not magic. The in circuit slew rate need only be "sufficient". It too is effected by the compensation.
Might I suggest doing some reading on the subject to understand compensation, input impedance, output impedance, and how they can effect the op-amp action. Otherwise, you are shooting in the dark and there is nothing relevant other than your one test, in your specific circuit, no matter how accurate your results are for you. ( I am not doubting them, please understand that) If you could learn how to adapt the circuit, and optimize for each device, then we can put your good ears to good use. It is not a black art, it is just basic circuits. Jung, Self, and Cordell are good places to start as are the data sheets and application guides for all the manufactures. Another way to learn about this is to play with SPICE. See what happens when you change the compensation and input impedance. Very quickly you will see there is a "right" answer. Of course, in your circuit due to para-statics, the actual right answer may be a little different. The problem in circuit design is that old " all things being equal". They never are.
Cog: Please be patient for a second. We want to help you with your "best of my knowledge" as we believe it could be expanded just a little.
I have no doubt just swapping chips may change the sound and a few people can hear the difference. I am sorry if you are cursed with hearing that good
You are jumping to the conclusion it is the op-amp that is causing the change, not how the op-amp interacts in the circuit. Hint: Undercompensate an amp, it may sound edgy. (at the limit, just oscillate or latch up) Overcompensate it it will be smooth but flat. I could easily see this in the wave forms of my Hafler 120 when I converted it from VAS loaded compensation to TM. A few puffs one way or the other made an audible difference.
Hint: Commonly used does not always relate to appropriate or optimal.
Hint: You are correct in "slew rate" is just a parameter. Not magic. The in circuit slew rate need only be "sufficient". It too is effected by the compensation.
Might I suggest doing some reading on the subject to understand compensation, input impedance, output impedance, and how they can effect the op-amp action. Otherwise, you are shooting in the dark and there is nothing relevant other than your one test, in your specific circuit, no matter how accurate your results are for you. ( I am not doubting them, please understand that) If you could learn how to adapt the circuit, and optimize for each device, then we can put your good ears to good use. It is not a black art, it is just basic circuits. Jung, Self, and Cordell are good places to start as are the data sheets and application guides for all the manufactures. Another way to learn about this is to play with SPICE. See what happens when you change the compensation and input impedance. Very quickly you will see there is a "right" answer. Of course, in your circuit due to para-statics, the actual right answer may be a little different. The problem in circuit design is that old " all things being equal". They never are.
tvrgeek,
I appreciate your effort and I think you are right, however I have always been one who is 100 times more likely to "tinker" with things than sit down and learn "the boring stuff". It is one of my faults that I have not been able to fix even after 42 years. Perhaps I still have a chance, and I'll be an electronics wiz when I am 80. Who knows?
But, isn't there room for those of us who can't be bothered to understand it all? There must be others, like me, who simply want to try different opamps in their particular device(s) to see which one they like the sound of best. Perhaps it isn't the opamp, but the circuit's response to the opamp; the point is, the sound changes (for better or worse) and we can decide which one we like best. Opamp rolling, for us, is "just tinkering"; a way to maybe find unexpected synergy, maybe not, in the true spirit of the "hacker".
I appreciate your effort and I think you are right, however I have always been one who is 100 times more likely to "tinker" with things than sit down and learn "the boring stuff". It is one of my faults that I have not been able to fix even after 42 years. Perhaps I still have a chance, and I'll be an electronics wiz when I am 80. Who knows?
But, isn't there room for those of us who can't be bothered to understand it all? There must be others, like me, who simply want to try different opamps in their particular device(s) to see which one they like the sound of best. Perhaps it isn't the opamp, but the circuit's response to the opamp; the point is, the sound changes (for better or worse) and we can decide which one we like best. Opamp rolling, for us, is "just tinkering"; a way to maybe find unexpected synergy, maybe not, in the true spirit of the "hacker".
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cogitech,
I have no problem with you doing as you say and tinkering. The problem comes when some that are tinkering turn that into hard and fast rules. I tried this opamp and it didn't sound good in my application and therefor it is a bad opamp. This is how so much misinformation is passed around in this area of audio. People making blanket statements that are just not accurate on their face. If I did as you said and liked the sound of a particular opamp I would probably leave it in the circuit as I would perceive it as an improvement personally. Then we get into the my gold plated so and so is better than your copper device because it cost 10 times as much and the website that sells it says it is better. Marketing is a major player in some of the snake oil sales that go on many times. A basic understanding will at least let you see when that is what is happening, not getting trapped by unreal claims or expectations.
I have no problem with you doing as you say and tinkering. The problem comes when some that are tinkering turn that into hard and fast rules. I tried this opamp and it didn't sound good in my application and therefor it is a bad opamp. This is how so much misinformation is passed around in this area of audio. People making blanket statements that are just not accurate on their face. If I did as you said and liked the sound of a particular opamp I would probably leave it in the circuit as I would perceive it as an improvement personally. Then we get into the my gold plated so and so is better than your copper device because it cost 10 times as much and the website that sells it says it is better. Marketing is a major player in some of the snake oil sales that go on many times. A basic understanding will at least let you see when that is what is happening, not getting trapped by unreal claims or expectations.