Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 28th July 2012, 05:36 PM   #1
diyAudio Member
 
Join Date: Jul 2012
Location: Hsinchu
Question Choosing op amps for Essence STX I/V stage

I recently bought a ASUS Essence STX, although it's far better than the integrated soundchip on my mainboard, I'm thinking about changing better op amps on the card.

I find some good op amps but choosing one from them seem to be a difficult trade-off on the electrical characteristics, the followings are what I found:

OPA627 (or similar ADA4627): Maybe the most well known audio op amp ever,
I found the PCM1704 from TI uses OPA627 in the I/V stage in the datasheet example diagram.
But its capacitive-load driving capability is very poor, I don't know whether it will cause ringing problem when driving the LPF stage.

AD8620: Has similar characteristics from the OPA627/ADA4627, but has a little bit higher input bias current and a little bit lower dynamic performance.
The capacitive-load driving capibility is far better (there is a comparison on the capacitive-load driving between OPA627 & AD8620 in datasheet p.14.)

AD827: A very fast op amp, originally designed for video purposes, but many people also use it in audio systems.
It really seems good for DAC output I/V conversion.PCM1794 datasheet says that
"Dynamic performance such as the gain bandwidth, settling time, and slew rate of the operational amplifier affects the audio dynamic performance of the I/V section."
And it can drive heavy capacitive-loads (With lots of internal compensations.)
But its noise is high in some extent for modern op amps.

LT1364: Similar to but faster than the AD827, and has the same questions.

LME49990/LME49720/AD797: These low noise and distortion series may be ideal for the preamp stage, many people also put them in the I/V stage and got satisfactory results.
But the dynamic performance is not so good as those ones above.
(I don't know how fast is really just enough for this kind of application.)

ADA4898: Transimpedence amplifiers do the job of "I/V conversion" so is it good to use those op amps with these kind of characteristic (such as low input resistance?)
(If it is true, then FET-input parts seem to be bad choices?)
High dynamic performance combined with low input resistance:
55V/s, 65MHz (-3dB freq.), Ri=5kΩ.
And its input noise is very low, too.


Or some people could recommend other good ones for me?
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Choosing op amps for Essence STX I/V stage delaluna Digital Line Level 21 28th November 2012 06:22 PM
Asus Essence STX Extension Oustide The Case? Drweird PC Based 42 6th March 2012 05:55 PM
New Asus Xonar Essence STX Drivers Brian Kingsbury PC Based 6 9th March 2011 09:52 AM
I2s from asus essence stx? bambadoo Digital Line Level 1 19th February 2011 01:05 AM
Issues Of Asus Xonar Essence Stx fotios Digital Line Level 0 12th May 2009 09:42 PM


New To Site? Need Help?

All times are GMT. The time now is 02:37 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2