Exactly. I agree the OPA690's distortion below 20 Khz is probably somewhat better, but we don't really know as it's not intended for audio so TI didn't even bother to specify the THD at audio frequencies. And even if it is a few dB better, it's still a long way from high quality audio op amps
Also very true. I mentioned in my write up it gets seriously hot driving low impedance loads due to that high dissipation. I kept my tests very short as I didn't want it to go up smoke. To me, the stress on the virtual ground is even more critical because if it fails it may well take your expensive headphones with it.
Thank you. I'm trying to help DIYers make more informed choices. I don't get why people like Linuxworks think I'm the bad guy here. I'm not the one promoting blatantly false information, myths and hype.Yes, kudos to you for exposing the BS in this.
Go to the thread on 'Logic vs Emotion' and read the article there. You're offending people's religious beliefs here, so you're bound to attract some flack.
When I say 'religious' I mean it in a broad sense of non-falsifiable beliefs which are used as pretexts for action. I don't mean it in the narrow sense of organised religion
The great thing about most of science is much of the work has long since been done, well proven, reviewed many times over, and has stood the test of time. When you let go of your cell phone you know it's going to fall to the ground not float off into space because the laws of gravity dictate what's going to happen.
I don't have to be any kind of magical authority... I only have to understand basic electrical engineering and be able to reference the guys who did all the hard work long before I was even born. Anyone who understands the technical aspects of this discussion can verify the basic engineering. I'm not out on some limb here.
What Ti Kan claims is little different than letting go of your phone and having it float into the sky. He's proposing things that go against the most fundamental of electrical engineering knowledge. 1+1 = 0.5 in Ti Kan's mysterious parallel universe.
If he's really right, why doesn't he just demonstrate where I'm wrong? Instead he banned me from his forum when I haven't violated any of the terms or conditions there. What does that tell you about his side of the argument?
You have it the wrong way around. Saying 'the laws of gravity dictate' is like saying 'the rules of grammar dictate what I say'. They do not dictate, they describe what habitually happens. 'The laws of gravity' are human inventions - rocks were falling out of the sky long before the 'laws' were dreamed up.
Ok, perhaps not the best analogy, but I was trying to relate electrons to gravity. Both behave in ways that were largely well documented long ago. And, for the purposes of this discussion, the science is not open to debate. Linuxworks seems to think the basic rules of electricity are somehow open to discussion like it's some unproven "gray area" that nobody (least of all me) can be certain of. That's convenient for audiophile myths, but just not true in this case.
In my book, linuxworks and AMB are part of the "good guys". Meaning they give out a lot of info for free and produce very affordable and well made and easy to use kits for the diy community. Rocketscientist is also part of the "good guys", giving objective analysis and reviews to many affordable components. I appreciate the contribution of all these parties. I hope the "friction" will not discourage anyone of them from continuing contributing.
I agree with the concept and generosity. I have, in the past, complimented the AMB website many times. There are also some generous people sharing their tube headphone designs with the world. And I'm sure those designs have performance issues as well, but they don't make claims that are not true (that I've seen).
If AMB just put their designs out there "as is" (like the tube guys tend to do) that would be one thing. But, instead, AMB makes a bunch of "seductive" claims for their designs that are simply not true. Several of those claims are completely wrong and could easily mislead someone into choosing an AMB design over another better performing one. And AMB isn't doing the community any favors blocking discussion of the factual errors on the AMB website.
Linuxworks might do an amazing job with microcontrollers, and if so, that's great. But he's been trying to discredit me (it goes well beyond his comments in this thread) since my review went up. Why? He's not doing anyone any favors trying to suppress objective information about DIY designs.
If someone says "I don't care if my amp measures well I like how it sounds", I'm fine with that. That's the case with most of the tube designs out there. But when someone comes along and puts designs out there, sells parts for them, and makes a bunch of false claims for those designs, I think that's wrong and a disservice to the DIY community.
you seem like you are out on a hit-job for 3ch designs and some designers, personally, as well.
I wish I could understand why you have this 'mission' to show the world how 'wrong' these other respected designers are. but it comes off very distastefully. if you are going to make a go at being a professional reviewer, you need to stop attacking the designers with your "I'm right and they are clearly wrong' approach. summarily concluding that your views are the only valid ways to look at such and such an idea won't get you endearment. this is one of the things that causes people to discredit you, pretty much immediately.
perhaps try to understand why the designs work they way they do. maybe acknowledge that there may be things going on that you just don't see. perhaps there is a difference in how the devices are being tested. there are a lot of unsettled IFs. but to set yourself up as the final judge on a very complex issue is, well, I'll say it again, arrogant beyond belief. your statements accuse the designers of either outright lying, incompetance or ignorance. while I'm not one of the designers of this topo, I find it insulting that you would imply this about people that you know almost nothing about.
I wish I could understand why you have this 'mission' to show the world how 'wrong' these other respected designers are. but it comes off very distastefully. if you are going to make a go at being a professional reviewer, you need to stop attacking the designers with your "I'm right and they are clearly wrong' approach. summarily concluding that your views are the only valid ways to look at such and such an idea won't get you endearment. this is one of the things that causes people to discredit you, pretty much immediately.
perhaps try to understand why the designs work they way they do. maybe acknowledge that there may be things going on that you just don't see. perhaps there is a difference in how the devices are being tested. there are a lot of unsettled IFs. but to set yourself up as the final judge on a very complex issue is, well, I'll say it again, arrogant beyond belief. your statements accuse the designers of either outright lying, incompetance or ignorance. while I'm not one of the designers of this topo, I find it insulting that you would imply this about people that you know almost nothing about.
I for one don't believe you do wish to understand. Rather you wish to smear because you feel insulted. None of your arguments are directed at errors or oversight's in RS's work, rather its a litany of character asassination with zero basis in reason or reality.
I offered, more than once, to help resolve the issues on the AMB forum. But instead of being open to that offer, AMB insisted there wasn't anything wrong and later banned me completely.
I'm trying to stay to the facts, and you keep trying to make this personal. If anyone is on a "hit-job" it's you trying to personally attack me by calling me arrogant, etc. Go ahead and call me arrogant if you want, but that doesn't make 3 channel designs work any better or change any of the other AMB claims I've questioned. You keep attacking me and avoiding the facts which are all I'm disputing.
You keep implying there are all these "if's" or "unknowns" but most of what I've put out there is really very straightforward and easily verified. Some of what's on the website is analogous to reversing gravity. It's literally impossible.
I don't need to know anything about someone personally to judge if 1 + 1 = 0.5. AMB could be the nicest guy on the planet for all I know. But if he's going to publish grossly misleading information to DIYers who are trusting him as an authority, he should at least be more open to having the information corrected and improving his designs.
If you're referring to the thread on AMB's forum, I have read it. Is there something else I should be aware of like you picked up a 'criticize at will' card last time you passed Go?
you came in to argue and argue and insult. that is probably why you were banned.
rather than trying to understand why you and he (and others) came to different conclusions, you assumed you were right and wanted everyone in the world to know this.
its fine that you found some issues with the designs and want to understand them. you don't seem to want to understand other viewpoints, you simply conclude that your reasoning is flawless therefore others are out and out wrong.
if you were the scientific person you claim to be, you'd want to understand why this disconnect is happening (in your view of the tech as compared to those that designed this concept).
but you refuse to allow for the possibility that there are issues you are not seeing. you set yourself up as the one to decide that this concept of virtual ground channels is 'all wrong'. and you keep implying that its childs play (1+1) and that everyone should conclude the same as you.
I have had enough of this, truly. you are not really in a fact finding mission. that much is abundantly clear.
Before I even "came in" there were several posts already attacking me and the review. So I was put on the defensive from the start. The most insulting posts in that entire thread are yours directed at me. So why weren't you banned? I did not violate any of the terms or conditions of the forum. I didn't call anyone names, use offensive langauge, etc. You kept trying to provoke me, just like you are here, but I kept trying to bring the discussion back to the facts.
But neither you, nor it seems AMB, wants to be bothered by mere facts. You seemingly would rather put your head in the sand and ignore the real truth. Suit yourself, but don't try to shoot the messenger.
Something I don't get in your review...
You write:
Isn't it exactly how the mini3 already works ? All the grounds points but the output ground are returned to the tle2426 output. Nothing but the headphones are connected to the opa690 output (well, and the opa690 inverting input as it's unity gain).
You write:
Isn't it exactly how the mini3 already works ? All the grounds points but the output ground are returned to the tle2426 output. Nothing but the headphones are connected to the opa690 output (well, and the opa690 inverting input as it's unity gain).
You are correct! Thank you. I'll update the article now. There are some virtual ground designs where this is not done (i.e. everything shares the same virtual ground) and I was assuming the Mini3 was in that group.
I guess on the one hand it proves what I was suggesting works. But I should have caught that on the schematic. Thanks again.
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