What's current "best" opamp for active filtering? - diyAudio
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 30th April 2011, 04:23 PM   #1
sdad is offline sdad  United States
diyAudio Member
 
Join Date: Jan 2011
Location: Grand Ledge, MI
Default What's current "best" opamp for active filtering?

What's current "best" (maybe 2nd best, if cost is considered) opamp for line level active filtering, audio range? Home application, so standard bipolar +/- 15v supply is good. Either single or dual package good, quad, not so much.
  Reply With Quote
Old 30th April 2011, 08:44 PM   #2
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
You'll be hard-pressed to find somebody that can hear the audio signature of an OPA2134.
  Reply With Quote
Old 30th April 2011, 08:47 PM   #3
diyAudio Member
 
Andersonix's Avatar
 
Join Date: Jan 2004
Location: Silicon Valley
LM4562!
  Reply With Quote
Old 30th April 2011, 08:48 PM   #4
mbar is offline mbar  Poland
diyAudio Member
 
Join Date: Dec 2010
MC33078

Sent from my Milestone using Tapatalk
  Reply With Quote
Old 1st May 2011, 07:13 AM   #5
Calvin is online now Calvin  Germany
diyAudio Member
 
Calvin's Avatar
 
Join Date: Nov 2004
Location: close to Basel
Hi,

as usual the answer is...it depends.
In this case it depends on the type of filter and the connected to it parts.
Generally the OP-Amp should not react much to different and varying impedances between their inputs. Gross impedance imbalances may lead to excessive output offsets. An example for such a situation are DC-servos/Integrator where one input sees 0Ohm while the other may see 1MOhm. FET-Input devices are less affected in this regard, because of their much lower input currents. If the source impedances the OPsees exceed ~2kOhms, FET-Input devices may be less noisy due to their much lower current noise. The typical FET-Input candidates are also all low enough in voltage noise for usage in low source impedance circuits.
In most filter applications the bandwidth limit of all OPamps exceeds the requirements by far. Very fast OPamps need more care regarding the power supply lines (hence PCB-layout and associated parts) than ´slower´ devices. So there´s in majority no necessity for fast wide bandwidth parts.
So if You are willing to mix technologies bipolar input OPamps may be suitable certain cases. If You want one device for all a FET-input OPamp should be Your choice.
If cost is a factor FET-devices like OPA604, OPA132, OPA134, or AD711, AD825(featuring a OPamp unusual high OL-bandwidth of >10kHz) and bipolars like the NE5534 or NJM4580 and their Dual and Quad brethren are suitable.
If cost is no object FETs like BB/TIs OPA627, OPA827, AnalogDevices´s AD743, AD8610 come to mind as well as the bipolar AD797 and some of the LME-Series of NationalSemi.

jauu
Calvin
  Reply With Quote
Old 1st May 2011, 07:33 AM   #6
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
> If You want one device for all a FET-input OPamp should be Your choice.

My choice in any case.
With modern FET input opamps, the noise advantage of BJT opamps becomes insignificant at line level.

> If cost is no object FETs like BB/TIs OPA627, OPA827, AnalogDevices´s AD743, AD8610 come to mind ...

You should try something modern like the OPA1641/2 for FET and OPA1611/2 for BJT.
And they are not even expensive.


Patrick
  Reply With Quote
Old 1st May 2011, 07:38 AM   #7
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
If I were to use a Sallen Key with no gain, I basically only need a follower.
In such cases, I shall definitely use a pair of JFETs such as 2SK372 or 2SK369, as in :

A Compact, High-Performance Source Follower Module


Patrick
  Reply With Quote
Old 1st May 2011, 07:53 AM   #8
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 96
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
NE5532 is best bang for the buck by a long way, so long as you're not asking for gain as well as filtering. If you are, then something with a bit more GBW would be appropriate - perhaps LM4562.
__________________
It doesn't have to take the form of a conspiracy, rather a consensus... James H Kunstler
  Reply With Quote
Old 25th March 2013, 09:44 PM   #9
diyAudio Member
 
lehmanhill's Avatar
 
Join Date: Jan 2008
Location: Chelsea, Michigan
Quote:
Originally Posted by EUVL View Post
>
> If cost is no object FETs like BB/TIs OPA627, OPA827, AnalogDevices´s AD743, AD8610 come to mind ...

You should try something modern like the OPA1641/2 for FET and OPA1611/2 for BJT.
And they are not even expensive.
Patrick
Patrick and all,

Thanks for bringing the OPA164x series to my attention. Looking at the specs, these are very nice opamps for a good price. Of course, specs are good, but they don't always tell the whole story.

Has anyone compared the OPA1641/1642 to OPA627 for how they sound? The OPA627 is pricey, but my choice for high quality signal path opamps. It would be nice to get an opinion or two about how the OPA1641 compares.

Thanks in advance.

Jac
  Reply With Quote
Old 26th March 2013, 02:14 AM   #10
diyAudio Member
 
Andersonix's Avatar
 
Join Date: Jan 2004
Location: Silicon Valley
Because of the low distortion levels these new op amps have, one is closer than ever to listening to the ps quality.
  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
4-way Active (3+1 way) TL 15" 8" 3" 1" cka3o4nuk Multi-Way 44 25th April 2011 02:26 PM
Jfet/opamp "hybrid" phono stage 00940 Analogue Source 8 11th March 2011 06:29 PM
"A Continuous-Time Active Filter", AudioXpress Magazine, Aug 2010 Dr. Ram Analog Line Level 4 4th August 2010 03:15 AM
Comb Filtering from "mesh" pjpoes Multi-Way 11 14th March 2009 01:39 PM
Reconstruction filter from "Opamp applications" (Jung) 00940 Digital Source 7 10th November 2005 09:19 AM


New To Site? Need Help?

All times are GMT. The time now is 03:24 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