Precision op-amp RIAA pre.. - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, 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 1st April 2010, 04:04 PM   #1
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Default Precision op-amp RIAA pre..

Hi all,

I have designed (filter circuit is inspired from an internet project that I already forgot) that about one year ago. However couldn't find any chance to make it until now.

It's a mixed filter stage (passive+NFB) and battery powered (4.8v) MM type preamp. in the simulation its RIAA curve accordance in 20Hz-20KHz band is +/- 0.05dB max with 1% resistors and 5% capacitors. I have already purchased 0.1% resistors and 1%capacitors (all MKP except 220) from Farnell. So I am expecting better results.

Since its battery powered I am using a virtual ground circuit that provided by a TLE2426. Its actual gain is ~41dB (@1Khz). It has capability to upgrade for MC heads with a simple resistor changing. The opamp (OPA4353) I use is an audio grade BB CMOS opamp since its rail to rail and low power one.

LM317 stage is just for battery charging nothing about the circuit.

So may you share your advices about my RIAA preamp please..

Thanks in advance for anykind of comment or recommendation..
Attached Images
File Type: jpg dualstage.JPG (127.3 KB, 630 views)
__________________
Best regards,
Ozgur
  Reply With Quote
Old 3rd April 2010, 08:28 PM   #2
diyAudio Member
 
Join Date: Nov 2008
If you are using a 5V supply you will not get enough distortion-free headroom. Maybee 2x9V or a V-up converter?
0.1% R and 1% C will make the circuit more accuarate in inaccuarcy. To obtain a proper equalization curve a far more complex feedback network is required.
  Reply With Quote
Old 9th April 2010, 12:17 AM   #3
rjm is offline rjm  Japan
Richard Murdey
diyAudio Member
 
rjm's Avatar
 
Join Date: May 2004
Location: Kyoto
Blog Entries: 103
5% tolerance capacitors implies +/- 0.5 dB RIAA accuracy, your 0.05 dB figure is calculated for the components as exactly the stated value.

The circuit itself is straightforward and reliable... except for the headroom issue brought up previously. If your want the simplicity of running from a low voltage battery an all active RIAA filter would be a better option.
__________________
RJM Audio (phonoclone.com / G+)
  Reply With Quote
Old 9th April 2010, 09:03 AM   #4
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Thanks for the advices..
Concerning the PSU headroom issue;
USB-Powered High Precision Hi-Fi Phono Preamp - Maxim
What do you think about that? My op-amp specs are very similar to MAX4478.. So I am expecting no hearable distortion even with 3,6v suppy!
And what do you think about the TLE2426? Is it enoughly noise free for that position do you think?
__________________
Best regards,
Ozgur
  Reply With Quote
Old 9th April 2010, 04:47 PM   #5
diyAudio Member
 
Holger Barske's Avatar
 
Join Date: Jan 2001
Location: Ruhrgebiet
Quote:
What do you think about that?
Fantastic. Fed from 3.3 Volts...
"High Precision" for those guys is something completely different from what it is for us audio people. That circuit is intended to be used in "50$ special offer USB out" turntables. Quality isn't the biggest issue there.
__________________
Best regards: Holger
www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum
  Reply With Quote
Old 12th April 2010, 07:34 AM   #6
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
Right.. But if you take a look my filter design and opamp specs then you'll see my pre will be a really precision RIAA opamp!
I cannot see any reason that a "rail to rail low distortion and low noise" opamp will not give good results with that level of supply voltage! Which is really comparable with LM4562, OPA604, OPA134, AD797 type popular opamps..
__________________
Best regards,
Ozgur
  Reply With Quote
Old 13th April 2010, 01:10 PM   #7
oshifis is offline oshifis  Hungary
diyAudio Member
 
Join Date: Mar 2004
Location: Budapest, Hungary
Ozgur,

Precisely following the anti-RIAA curve is one thing. The final sound quality is determined by many other factors, starting from the choice of the gain element (opamp and type thereof, BJT, FET, tube), topology (feedback or passive equalization), power supply (3-legs, discrete, battery) etc. I also built a phono similar to yours. It was technically "perfect" but sonically inferior.
  Reply With Quote
Old 13th April 2010, 01:15 PM   #8
Dxvideo is offline Dxvideo  Turkey
diyAudio Member
 
Dxvideo's Avatar
 
Join Date: Nov 2003
Location: Turkey
Send a message via Yahoo to Dxvideo
I am absolutely aggree with you..
My components arrived just this morning.. I guess I will finish the project by this weekend and hear the results next week.
My filter topology, component selection and psu (which is only battery) is best I can do. I hope the results will the best also
I'll inform you about the impressions next week.
Thanks for the sharing.
__________________
Best regards,
Ozgur
  Reply With Quote
Old 27th November 2010, 09:19 PM   #9
diyAudio Member
 
regiregi22's Avatar
 
Join Date: May 2009
Location: Madrid (Spain)
how is it going?
__________________
diyAudio, doing it as big as you can, JUST BECAUSE WE CAN!
  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
Needs simple RIAA pre-amp parmar664 Analogue Source 2 30th March 2007 11:29 PM
Pre-pre; phono; pre line ;device discrete (bjt/fet) o op. amplifier GIPIONE Solid State 8 18th December 2005 10:09 PM
RIAA pre amp jethari Solid State 1 30th April 2002 05:21 AM
Trimodal Power amp and Precision Pre amp petekav Everything Else 6 11th February 2002 08:18 PM


New To Site? Need Help?

All times are GMT. The time now is 04:56 AM.


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