Amazing opamp measurement shoot-out

[darkfenriz]

Forr,
you got mail

[lineup]

Amazing opamp measurement shoot-out:

http://recforums.prosoundweb.com/index.php/t/24704/0/

Any kind of shootout, will be biased in some way, by the intent, the hypothesis or desire of the investigator.
- selection of objects to test
- selection of parameters to test
- and parameters not to test
- selection of data presentation of test result
- the conclusive statement, opinion of the tester

Nevertheless, any such comparing test performed
can give us some useful additional knowledge and information.
So is very welcome

[lineup]

Here is the PDF Document for download

Operational Amplifier Distortion
by Samuel Groner, 1 September 2008
http://www.sg-acoustics.ch/analogue_...distortion.pdf

[lineup]

Notice that Scott Wurcer is mentioned in the reference list:

[13] Scott Wurcer:
An Operational Amplifier Architecture with a Single Gain Stage and Distortion Cancellation
AES preprint No. 3231, March 1992

Along with such great men as
Douglas Self
Walter G. Jung

[janneman]

Originally posted by lineup
Notice that Scott Wurcer is mentioned in the reference list:

[13] Scott Wurcer:
An Operational Amplifier Architecture with a Single Gain Stage and Distortion Cancellation
AES preprint No. 3231, March 1992

Along with such great men as
Douglas Self
Walter G. Jung

In this preprint Scott describes the design of the AD797.
And while I have a lot of respect for WJ, please note that Scott is an IC designer while Walt is an application engineer. Different roles.

Jan Didden

[Ryssen]

what's up with njm4556, njm4580 and all that stuff that populates modern digital low- to high grade digital interfaces?

Just found out that the 4580 sounds better in my Behringer DEQ2496 than LM4562.
I´m thinking on changing it back to 4580.Is the 4580 realy that bad that everyone is saying?

[Pan]

I think there's a bunch of those in the Echo Audiofire4 and that converter is close to transparent in loopback so I think calling that IC bad would be a stretch and then some. :-)


/Peter

[Ryssen]

to high grade digital interfaces?

It would be nice to know how expensive gear CD,DVD the 4580 is used in.
I now Denon DVD3910 uses them,any more expensive than that?

[gaetan8888]

Originally Posted by john curl

Carlos, I have answered you the best way that I can. I really don't have any absolute opinions on this subject. The biggest problem with IC's, in my opinion, is that they tend to starve the output stage in order to save current, and this causes higher order distortion to be generated. ALL my discrete preamp circuits operate in class A, and don't have this problem.

Hello John

The THS4031 do have an higher bias (close to a class A) than most Ic.

For myself I allway use my Ic into class A with a resistor or a CCS from rail to ouput, but the THS4031 may not need it since its high bias.

Thank

Bye

Gaetan

[stocktrader200]

At the risk of being run out of town, I keep coming back to the LF353
I have used several of the other amps including the LM4580.
The key I think is to use these op amps at high frequency gains less then 5
The phono stage uses a low noise bipolar front end (Av =20) overall s/n = 93db.
I noticed that this amp (LF358) had very linear distortion curves.
In practice , it is almost impossible to get them to oscillate with an appropriate output decoupling resistor.
The latest project has a LF353 a/d 1st stage in my 1.3 mhz class d amplifier
with spectacular results.