RIAA Network Transfer Function - diyAudio
Go Back   Home > Forums > Design & Build > Software Tools

Software Tools SPICE, PCB CAD, speaker design and measurement software, calculators

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 26th March 2012, 01:10 PM   #1
BRSHiFi is online now BRSHiFi  United States
Previously known as kingden
 
Join Date: Aug 2008
Location: Evanston, IL
Default RIAA Network Transfer Function

Does anyone know how to find the component values for the attached RIAA network?

I am building a tube differential phono stage and will verify it spice.
Attached Images
File Type: png Untitled.png (3.2 KB, 212 views)
  Reply With Quote
Old 26th March 2012, 01:55 PM   #2
godfrey is offline godfrey  South Africa
diyAudio Member
 
Join Date: Nov 2009
Location: Cape Town
Where's the input and output?
You also need to take into account the source and load impedances.
  Reply With Quote
Old 26th March 2012, 08:46 PM   #3
BRSHiFi is online now BRSHiFi  United States
Previously known as kingden
 
Join Date: Aug 2008
Location: Evanston, IL
More specifically, the circuit is like this. The network is between the two differential outputs.
Attached Images
File Type: png Untitled.png (15.6 KB, 195 views)
  Reply With Quote
Old 26th March 2012, 09:18 PM   #4
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
Look here, this seems to be the equivalent topology to what you have in mind :
phonostage

General information :
Cut and Thrust: RIAA LP Equalization | Stereophile.com

And in LTspice, a reference can be simply constructed with an AC voltage source of magnitude 10 connected to an "e"-source (VCVS) with the transfer function given in direct Laplace notation, using the known time constants :
laplace (1 + 318u*s) / (1 + 3180u*s) / (1+ 75u*s)
Comparison with the Stereophile article shows 100% precise accuracy (compare the detailed numbers given in the text) as expected right away, but always better double check

Last edited by KSTR; 26th March 2012 at 09:22 PM.
  Reply With Quote
Old 26th March 2012, 09:28 PM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I think it is Harm that gives a method to determine the component values.
There is also a method given by one of our audio celebs, Bax or JLH or ??
__________________
regards Andrew T.
  Reply With Quote
Old 26th March 2012, 10:24 PM   #6
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
Calculation, for a starting point, is quite straightforward. RIAA EQ is a one decade wide bass shelf (from 50Hz to 500Hz) with a pole on top (at 2.1kHz). Problem is the somewhat ill-defined plate impedance of the tubes for the actual circuit which influences all three time constants, being part of the source impedance the network works upon.
  Reply With Quote
Old 26th March 2012, 10:36 PM   #7
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
I've attached the topology you want. There's an RIAA calculator here: KAB Electro Acoustics http://www.kabusa.com which you can use as follows.

Connect the two resistors marked R! in my drawing to the 12AX7 plates. For the R1 value in the calculator, use 2 times R1 in the drawing plus two times the source impedance of the driving stage (the formula for the source resistance of a diff amp may be found in Morgan Jones's "Valve Amplifiers" as well as any other standard tube text. The other components can be directly plugged into the KAB calculator.
Attached Images
File Type: png bal riaa.png (4.3 KB, 183 views)
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 27th March 2012, 01:35 AM   #8
BRSHiFi is online now BRSHiFi  United States
Previously known as kingden
 
Join Date: Aug 2008
Location: Evanston, IL
Tried it in simulation. I receive what resembles an RIAA curve, but the voltage differential is supposed to be reasonably flat, as I am running inverse RIAA networks on the inputs, along with the sine wave generator to simulate a cartridge.

The plate impedance for a 12AX7 is around 70k, in parallel with 220k, and double those quantities is about 560k. I put the values in the calculator and came up with the values in the schematic below. I wondered if I calculated it properly?
Attached Images
File Type: png Untitled.png (18.3 KB, 172 views)
File Type: png Untitled2.png (25.7 KB, 173 views)
  Reply With Quote
Old 27th March 2012, 02:00 AM   #9
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
You really do want to incorporate the build-out resistors- that will lower distortion, especially at high frequencies, and reduce the dependence of the frequency response on tube aging and drift. There is something of a noise penalty there, unfortunately. There are also ways around that, but with added complication.

Let's pick 100k as the buildout resistor. The equivalent series resistance is then 200k + 2x RL||Rp. The second term is about 53k, so the total equivalent resistance is 306k. Plugging that into the KAB kalculator, R2 is 44k5, C1 = 7n15, C2 = 2n45.
__________________
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
  Reply With Quote
Old 27th March 2012, 02:17 AM   #10
BRSHiFi is online now BRSHiFi  United States
Previously known as kingden
 
Join Date: Aug 2008
Location: Evanston, IL
What are the build-out resistors? Where do they go?
  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
transfer function jenks Solid State 31 24th April 2008 09:28 PM
Sound card transfer function NIC1138 Digital Source 9 15th July 2007 01:15 AM
Transfer Function jclouse Multi-Way 22 1st July 2006 02:19 PM
SPICE transfer function for RIAA testing Onvinyl Analog Line Level 28 3rd March 2006 06:40 PM
Transfer function of closed box cm961 Multi-Way 1 31st August 2004 07:42 PM


New To Site? Need Help?

All times are GMT. The time now is 10:55 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