OPA2107 (some personal impressions and vs 2227, etc.)

[millwood]

the whole discussion reminds me of the gainclone discussion in its earlier days. at first, everyone was building inverting gainclones because they sounded so much better than the non-inverting versions, and there were many sound scientific reasons why that was the case.

then a couple years later, the wind shifted and everyone was building non-inverting gainclones because they apparently sounded so much better than the inverting gainclones. the same people who were advocating inverting gainclones were denouncing anyone and their mother who dared to praise inverting gainclones.

....

the same thing is happening here. I have no doubt that those chips are different. and i have no doubt that some of us heard the difference, real or psychologically. But the fact that there are such divers opinions on those chips suggest, to me anyway, whatever the differences are, they are small and can be easily overwhelmed by other factors: if those chips were night and day different, we wouldn't have such diversity here.

Quote:

the AD797BRZ is the only one I could say transparent and not sounding like op-amp.

I would 2nd that for ad797. that is a great chip.

my other favorites are ne5532/34 (nice sounding, smooth, easy to deal with and cheap), ad815 (large current capability, straight forward and authoritative), and ths4012 (to the point).

 

[rembrant]

Now my hearing is unreliable? What is your malfunction? I'm not really sure what I have done to offend you.
First. The reason I looked up the info to begin with is because I have not heard any of these opamps at all, and certainly none in a Cmoy amp. So explain to me exactly how I am supposed to know what it sounds like without trying it. If I can't trust head-fiers then who can I trust. It has also been known that some of these folks are very passionate about what they hear. What one man hates is another one's treasure.
I know I will get shunned for this. I personally like the sound of the headbanger amp that Stephen Lafferty designed and is posted on minidisc.org. What does that say about my "desire to conform" It's quick, it's clean, and it is flat throughout the audio band. Many people here would dismiss it right out of the gate because it goes against conventional though in a lot of areas. Big EL caps in the signal path, old chip, Etc. I built one a few years ago and I still use it everyday. I decided to try the Cmoy to see if I was missing anything. Time will tell.

You certainly seem to know everything for only being around here for a short time. From what I have seen of your posts I am not so sure your helping this little community at all. Try to practice a bit more humility, and perhaps we can all get along.

 

[millwood]

Quote:

Originally Posted by rembrant /img/forum/go_quote.gif Now my hearing is unreliable?

calm down, will you?

I wasn't talking about you, or with you, at all. It was an observation of the diverse of opinions and why they exist.

chill out.

 

[krisjan]

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Originally Posted by millwood /img/forum/go_quote.gif isn't that why people do blind listening, rather than measurements, to judge sound quality?

You don't need to be blind to do that
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Originally Posted by millwood /img/forum/go_quote.gif so take the klippel test as many times as you want, whenever you want it.

A single test over and over is exactly what i want to avoid - the test is to listen to the same EQUIPMENT over an extended time period and to a diverse range of material...
Quote:

Originally Posted by millwood /img/forum/go_quote.gif there is a definite limit to any approach. That doesn't mean such an approach is invalid.

exactly my point - let me put it another way using the klippel test - if distortion is at 6db it's very east to assess - i don't need to be blind to assess it. If we get to the subjective nuances then sure do some blind tests (the most useful thing it seems about these tests is that it shows us whether we can discern something or not and therefore if it's even worth comapring)...
what i am saying is that the difference between the 2227 and 2107 is quite substantial - no need for a blind test - going through extreme scientific enquiries, statistical analysis, etc. This post is just my subjective first impressions...

 

[krisjan]

Quote:

Originally Posted by millwood /img/forum/go_quote.gif is the test done sighted or unsighted? in an unsighted test, how accurately do you think you can tell the chips based on their sound? on the offset: opa227 has a unique bias current cancellation circuitry that I haven't seen in other opamps. because of that, the conventional offset cancellation scheme will actually cause more offset - which may be what you are experiencing. on the hum: maybe you can ground your amp to the case?

so to ground it - do i just connect the case to the virtual ground?

 

[krisjan]

Quote:

Originally Posted by millwood /img/forum/go_quote.gif or a couple others who praised their superior sounding amp, only to learn that they were oscillating like crazy. so take the listening test I linked for you here (Listening Test - Instructions) and show us how you do on that test. you may learn a thing or two about your hearing.

two q's:
1> how does oscillation sound? like a vibrato? blurriness?
2> this is not actually a q - the klippel test is highly problematic because their reference sample is already severely distorted due to the compression they used to make it small enough for web, or sth - i compared it to the original cd...

 

[rds]

Quote:

two q's: 1> how does oscillation sound? like a vibrato? blurriness? 2> this is not actually a q - the klippel test is highly problematic because their reference sample is already severely distorted due to the compression they used to make it small enough for web, or sth - i compared it to the original cd...

1> Oscillation happens at frequencies way above the audio range. I don't think there is any sound signature to oscillation, although it would be expected to degrade the op-amps' performance.

2> Yeah, that test is flawed on many levels. First it assumes that the type of distortion they chose is what determines sound quality.
Second, in most cases you are playing the sample through a pc card and with compression (as you said). In that case the distortion effect they use is swamped by the card/compression distortion.
You could go on and on.
I think the bottom line is when someone tries to "debunk" you in this kind of way they are making all kinds of assumptions about your perceptions. I don't really like when people try to act like this is scientific. It's really not at all.
I think hifi audio is like you said originally - very subjective. All you really have to know is what you like.

 

[krisjan]

ok...tx for those replies...i see the word "Banned" under millwood's name - so he's gone? exciled? i must say, he was rather abrasive - must've ruffled one feather to many then...

 

[Earwax]

Yes, OPA2107 is very nice in a CMOY. There used to be some discussion of them now and then, I think it mostly got overlooked because it was hard to find and somewhat expensive.

One of the problems in comparing notes opamps is that nobody's heard them all and different people seem to judge differently. I pay attention to what majkel says about amps since his comments about the opamps I've heard are very close to what I think of the same opamps.

That poll that was linked only offered 4 choices. If those were the only opamps I could choose I'd have to take the 2227, but in a wider universe there are certainly better choices.

 

[krisjan]

Quote:

Originally Posted by majkel /img/forum/go_quote.gif Regarding more desktop applications. OPA2107 sounds simply worse than similarily priced and designed OPA2111. The last one is amongst the best dual op-amps but not perfect.

hey majkel - i had a look at the opa2111 specs and slew rate is very slow - similar to 2227 - don't you find it slow when you listen to it? anybody else has any experience with 2111?

Other thing is just regarding the actual intended use of opamps - i find it intriguing - some seem to be designed with audio in mind but others (which are often use in cmoys etc.) are actually designed with something totally different in mind - take the LM6172 - i don't know if i have the wrong spec sheet, but it has a slew rate of 3000v/us!! That seems way above other opamps, but then when i use tangent's calculator for dc offset i get very high dc offset values (the trade off for having such a good slew rate?)? Then i read it seems to be intended for imaging (video processing, etc.), and not really audio? Anybody have any comments on this chip?

 

[majkel]

The OPA111/OPA2111 were designed for professional audio many years ago. While the slew rate is low, it's still enough for audio purposes. I recommended this chip as I find it still as one of the best sounding op-amps, sure, not perfect, but given the choice between the OPA2111 and the OPA2107, I'd stick with the former without a doubt. I just don't know how the OPA2111 works with lower supply voltages, I mean a single 9V battery or something. With +-12V rails, it works fine.

Regarding the LM6172, its slew rate is that high but it's not all that makes an op-amp sound great. There are other, often unmeasurable aspects like say silicon purity and the technology of production. It's a pretty good choice for the Cmoy but might get unstable due to being so fast. When it's stable, it provides clean sound, somewhat colorless and cold. Class A biasing turns it a bit into sweet kind of things but it's not recommended to do it in battery powered devices.

 

[krisjan]

thanks for comments majkel - yes, of course i do not mean that slew rate is everything - it does not account for the frequency response, etc. in my cmoys i run mostly of wallpower - 12v to 24v...i hate it when you forget to turn (battery powered) cmoy off - so then when you return to the desk you always swear when you think of the power that was wasted...at least with wallpower that doesn't matter.k