The Opamp thread

[TigzStudio]

So I read through this entire thread, painfully, from start to finish.  What I gathered?  That basically everyone goes back and forth from liking one to not liking it, then a new one pops up... etc etc rinse and repeat.  There really doesn't seem to be a definitive opamp that people like and will stick with no matter what.  No end all opamp for anyone?
 
The ones that seem to be leaning in everyones favor would be the AD797 and the LT1363/4.  
 
In all of the opamp rolling what is the most neutral opamp you have encountered?  That is my ultimate goal.  If you can please list the one that beats all in this regard even if slightly.  I am not looking for colorations of any kind.  
 
Thanks!
 
btw: I would be swapping out 4x5532's in this amp
 

 

[majkel]

Quote:

In all of the opamp rolling what is the most neutral opamp you have encountered?  That is my ultimate goal.  If you can please list the one that beats all in this regard even if slightly.  I am not looking for colorations of any kind.  
 
Thanks!
 
btw: I would be swapping out 4x5532's in this amp
 

When I really have to use an op amp, I refer to OPA228 family. Otherwise, I skip op amps where possible.

 

[amb]

 
Quote:

So I read through this entire thread, painfully, from start to finish.  What I gathered?  That basically everyone goes back and forth from liking one to not liking it, then a new one pops up... etc etc rinse and repeat.  There really doesn't seem to be a definitive opamp that people like and will stick with no matter what.  No end all opamp for anyone?

What do you expect from such opamp fetish?

 
Quote:

If you can please list the one that beats all in this regard even if slightly.  I am not looking for colorations of any kind.

 
Good luck...  there are at least a couple things which makes that impossible:
 
1. Most people here talk subjectively about the "sound" of the opamp, but what's "neutral" or "uncolored" is a perceived entity and subject to interpretation.  (e.g., What one person considers "neutral" might sound "bright" to some and "laid back" to others).  What those words mean, even, are also fuzzy.
2. The opamp isn't the only factor at play here.  What circuit it's installed in also has an effect on the sound.  Sometimes more so than the opamp itself.
 

 

[TigzStudio]

Hmm good points, so I guess it really comes down to.... what amplifier design (that does not use opamps) is the least altering of the original signal.  
Quote:

 
What do you expect from such opamp fetish?

 
 
Good luck...  there are at least a couple things which makes that impossible:
 
1. Most people here talk subjectively about the "sound" of the opamp, but what's "neutral" or "uncolored" is a perceived entity and subject to interpretation.  (e.g., What one person considers "neutral" might sound "bright" to some and "laid back" to others).  What those words mean, even, are also fuzzy.
2. The opamp isn't the only factor at play here.  What circuit it's installed in also has an effect on the sound.  Sometimes more so than the opamp itself.
 

 

[TigzStudio]

Well I think for now I will just swap out the 4x5532's with this:
 
http://www.national.com/pf/LM/LME49723.html#Overview
 
or the LM4562

 

[majkel]

I suggest using LME49860NA. Surely better than the LM4562.

 

[Avro_Arrow]

So ADA4894 in the I/V role and LT1363 for the Filter role.
 
I want to use the soic version soldered directly to the board
so rolling would not be a very good option, thats why I would
like to start out with the best (oh, there's that word again...)
amps for those uses.
 
Thanks for your input.

 

[jcx]

my fingers slipped in my I/V op amp recommendation post - that would be ada4898, I fixed my post
 
http://www.analog.com/static/imported-files/data_sheets/ADA4898-1_4898-2.pdf
 
from info provided by Scott Wurcer it appears to use US 6963244 Common mode linearized input stage and amplifier topology

 

[Avro_Arrow]

No wonder I couldn't seem to find any information about it...
 
Quote:

my fingers slipped in my I/V op amp recommendation post - that would be ada4898, I fixed my post
 
http://www.analog.com/static/imported-files/data_sheets/ADA4898-1_4898-2.pdf
 

 

[Avro_Arrow]

The LT1363 data sheet mentions that it is suitable for the I/V role...could I not
use it for both the I/V role and Filter role and maintain it's high slew rate?
 
Any opinions on this?

 

[jcx]

only technical opinions...
 
lt1363 9 nV/rt(Hz) input noise is high for I/V role
 
slew rate requirement in audio is not 1000V/uS, - like output Vswing or current limit once you have sufficient margin over what the signal, load requires there is no obvious good from having orders of magnitude more
 
I highly advocate using a feedback C in a op amp I/V to give a low pass filter below 100 KHz - limiting slew requirement to  ~1 V/uS per V of output swing - with desktop consumer 2 Vrms output this means the "only" 55 V/uS ada4898 is already 10x faster in slew rate than the highest possible 100KHz filtered DAC I/V output

 

[Avro_Arrow]

Yes, I agree. I keep the ADA4898 for I/V.

The data sheet quotes a 2200pF cap in parallel with 750 ohms for the feedback in the I/V section
Is there any reason I should alter these values for use with ADA4898?
 
I did like the ADA4898 noise figues...
 
 
Quote:

only technical opinions...
 
lt1363 9 nV/rt(Hz) input noise is high for I/V role
 
slew rate requirement in audio is not 1000V/uS, - like output Vswing or current limit once you have sufficient margin over what the signal, load requires there is no obvious good from having orders of magnitude more
 
I highly advocate using a feedback C in a op amp I/V to give a low pass filter below 100 KHz - limiting slew requirement to  ~1 V/uS per V of output swing - with desktop consumer 2 Vrms output this means the "only" 55 V/uS ada4898 is already 10x faster in slew rate than the highest possible 100KHz filtered DAC I/V output

 

[Mad Max]

Quote:

So I read through this entire thread, painfully, from start to finish.  What I gathered?  That basically everyone goes back and forth from liking one to not liking it, then a new one pops up... etc etc rinse and repeat.  There really doesn't seem to be a definitive opamp that people like and will stick with no matter what.  No end all opamp for anyone?
 
The ones that seem to be leaning in everyones favor would be the AD797 and the LT1363/4.  
 
In all of the opamp rolling what is the most neutral opamp you have encountered?  That is my ultimate goal.  If you can please list the one that beats all in this regard even if slightly.  I am not looking for colorations of any kind.  
 
Thanks!
 
btw: I would be swapping out 4x5532's in this amp
 

There are a few I've tried that are the most neutral, and 1363 is one of them, but it requires really clean power or it will sound colored.  AD797 is [pleasantly] colored, but pratless and has crappy treble.
ADA4627-1B is the very best I've heard along with THS4081, the latter of which needs very clean power as well.

 

[razzz42]

I'm on the sidelines here since I'm handicapped technology wise. but hasn't this 'no amp' been discussed before starting somewhere around here....http://www.head-fi.org/forum/thread/287617/prelude-with-opa627-opamp#post_3693471
 
Not arguing the point as it is the finally the first thing that makes any sense as to listen to sounds as recorded on a pass through basis maybe some filtering needed but that is about it.
 
Then this leads back to the sound processing chip itself, in my case Envy Vinyl (which everyone seems to ignore which must be a good thing in this case) on a Prodigy HD2 Advanced DE. Just need a decent pass thru DIP8 or equivalent. (JP4 'on' just send the raw processing through, like for a home receiver to work with. )
 
Glad I caught on before I spent to much money trying to change the original recordings.

 

[jageur272]

I'm thinking about using a LME49710 as the voltage gain stage of an amp I'm building.  Is there any advantage to using the TO-99 package as opposed to the SOIC or DIP packages offered?