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In Reply to: RE: OPA211 - reportedly a higher grade version posted by reb on March 16, 2010 at 12:01:41
FYI- Response from a TI Application Engineer when emailed about this:
(to paraphrase)
The opa1611/1612 are optimized for better distortion figures than the opa211.(apparently, the opa211 is still pretty good in this area)
The opa1611/1612 are not trimmed for the lowest DC offset.
High levels of DC precision are generally not required by audio equipment manufacturers. So, parts are not specified or tested for the same levels of DC precision as a part, such as opa211, designed, specified and sold for DC precision.
..so it seems that the 20% or so less expensive opa1611/1612 is less good in an area that is less important in audio use and is better in an area that is more important.
Having no opa211s in my collection, I can't evaluate any sonic differences.
Dan
Follow Ups:
yes, i read the ti reply on another forum. not finding anything sonically great about the opa211- i feel non compelled to try the 1611. i'll stick with the opa827.
for iv conversion, i use the lt1364
Hi reb,
That must be the cut-and-paste TI response.....a number of us got similar/the same answer.
I can't wait to try out the opa827s, but they are backordered to TI. Delivery is expected in early April.
The lt1364 is a good solution in a dual op-amp with, to me, a pleasant "warmth" to its sound. I also forgot about the lt1028 single (a nice little BiPolar)--I've never "heard" them, so I requested a couple pair to try out on the dual adapter boards.
It appears that, like most, the opa211 is greatly effected by all associated circuitry. I've read wildly varying assessments of its sonics. I guess it's not a real "drop-in". The opa1611 seems pretty forgiving in that respect and has a fairly consistant "sound".
Did you find that the opa211 did anything especially wrong, or did it just not "have it", so far as SQ in general?
Any feelings about the old standby Motorola mc34082p touted by many as THE drop-in replacement for the ne5532/jrc4560/lm833 back in the late '80's? Some old-timers (like my age) still swear by them.
Dan
Hi,
"Any feelings about the old standby Motorola mc34082p'
If I heard this Op-Amp it would have to been already in the equipment as I never tried them as replacements. So I can't speak of their quality.
The NE5534, can sound good but I hear some phase issues going on that makes the bass/mids/highs sound- well out of phase with each other. Once you hear this issue, its hard to get passed it.
I have experimented with many Linear Technology OP AMPS and in general do not like them. Most exhibit exaggerated bass and midrange overhang. The LT1364 is easily the least "warm" and most transparent sounding LT I have tried, with the highest resolution and speed. That's why I use it for the IV conversion stage.
I found the OPA211 used as a filter/buffer to cast a coloration over the midrange. I found no area of its performance to excel at audio reproduction (in my highly modified cd player)
OPA827 are on back order again? And you mention that you have not heard them yet?..........well I think you will be pleasantly surprised with these.
They sound nothing at all like the old OPA627.
The OPA827 is perhaps the most transparent Fet OP AMP ever. It will take on the coloration of what precedes it- etc. This is my reference OP AMP for filter/buffer position.
On a side note. I also have an older Cal Aria MK3 cd player, that I modified. This player uses no OP AMPS at all in the signal path. Oh it has OP AMPS inside, but they are used to control the circuit parameters.
Point being is that listening thru this machine helped me fine tune my hearing to identify just what an OP AMP is doing wrong.
The first OP AMP in the signal path is the most crucial. Whatever damage that does can not be recovered further down the signal path.
Which brings me back to mentioning the LT1364/OPA827 combination. Easily the closet I've heard yet to a discrete circuit.
Thanks for the observations, reb!
Nope, I've had the 827s on backorder from TI since November. I've heard a lot of good things about them. Can't wait to get my hands on 4 of them!
I also missed out on the 627/637. They had a lot of positive press, but were known to be a bit "sterile" if I recall correctly.
I've played with a few LT chips. There were a couple (lt1469? maybe-it's been a bit) that were the opposite of the 1364-they wanted to stick needles in my ears with shrieking upper mids/highs and minimal bass.
If you shoot me a PM or email, I can send you out a couple of the mc34082p's to play with......very nostalgic, actually.
I remember the old Cal Aria....Cal Audio was quite the company back in the day.
Dan
OPA 627 has difficulty driving loads. Has a veiled colored mid-range, lacks dynamics and also can sound very hi-fi/sterile. If you glue a heat sink to them they sound much better and have quite a strong bass. But can't hold a candle to the transparent, color free 827.
Anyway, do you have any of the motorola chips in singles?
Thanks reb!
I guess I'll hang on for the 827s.
Sorry, I've only used 34082's which are duals. Never had any 34081's.
You're still welcome to a couple if you feel like playing, though.
Dan
Hey Dan and Reb - thanks for this great discussion. I have samples on the way of 1611, 1612, 2107, 827, 2211A and 2111. I ordered a SOIC-DIP 8 adapter from Brown Dog, too. I have a 627 here already that I haven't yet plugged in since I am still getting familiar with the 2132A.
And I can't recall if I mentioned that I am using this in an old Belles DMM pre that I have modded pretty heavily (and BTW it sound FANTASTIC in my system).
Here is another question for y'all. I ask this knowing full well that it isn't answerable directly.... I have a new Quad 99 pre. It has 12 OPA275s in it. I am toying with the idea of pulling them all and installing sockets to put new/better opamps in. I don't have a schematic, so I can't tell you the specific uses of the opamps in the circuit, but in a general sense, what would you recommend as replacement/upgrades for this? I am also going to try to ask Quad directly, but I don't anticipate getting an answer.
Thanks
Hey bevo!
Quite a fun discussion, eh?
Looks like you'll have quite a collection to do some op-amp rolling!
Was the 827 off backorder yet?
You will really need a schematic to play with the 99. Looks like it's about majority IC, with few discrete components. It would be pretty easy to upset the "balance" of things.
I couldn't know which to start replacing first, or with what, until you know "what goes where". I don't know how cooperative Quad is at providing schematics to non-techs, but it's worth a shot.
Nice project, though. Good luck!
Dan
Yes - it has been fun for me. This is my first time to play around with opamps. Yes, the 827 is on BO until 1st week of April. A couple others are on BO as well..
I sent a message to Quad - we will see what happens. I have already voided the warranty by replacing all the crappy 'lytics with Nichicon FGs in the power supply and Mundorf nonpolars in the phono stage. Also replaced both rectifier bridges with new ones from Fairchild. The PCB is not the best quality - lots of traces separated just from desoldering/resoldering the caps. And there were even trace separations that the factory had repaired before I even touched anything. Even though I did exact replacements for capacitance (higher V rating, though), something went wrong and it won't pwer up. From what I can tell from the PCB test points, I have lost 2V on the - power leg. The toroid output is correct, all fuses are good and the resistors I have measured are all good. I am afraid a regulator has gone bad somehow/somewhere.
I am anxious to get it up and running to do a head-to-head with my Belles. I think the Belles is winning, even with the OPA2132A...
Yep, I think that the opa1612s are b/o as well, but I thought that they were a mid March availability. I'll have to check my invoices.
While you were digging in to things, did you replace the resistors in the phono stage? I recall an old Quad preamp mod was to replace them all with like-value 1% metal film from Holco, Vishay or other "high end" ones.
Did you also do a bypass of all of the 'lytics with HQ PP/PS/whatever caps?
re: board quality-no surprise here...I've opened up a few "high end" components and had one of those WTF moments in regards to build/material quality. I've (luckily) never had a trace lift, but it has to be exasperating.
At least the regulators look to be up front and easy to test/replace.
My suspicion is that the Belles will win in any case. As has been said many times before;"The best op-amp is none at all." By extension, the fewer, the better.
Remembering that the Quad equipment (at least the ones with which I'm familiar) were "voiced" to match/compliment the Quad speakers. By design (and intent) they seemed to showcase the lower midrange to mid/upper-treble range. Extreme highs and bass were less important. This is based on old knowledge with the ESL57/63 and Quad electronics through the model 77.
This might well have changed over time and with customer request/marketability....
Happy Hunting :-)
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