Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

The Phonoclone and VSPS PCB Help Desk
The Phonoclone and VSPS PCB Help Desk
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 8th February 2018, 03:11 PM   #3961
ALPUY is offline ALPUY  Uruguay
diyAudio Member
 
Join Date: Mar 2012
Location: Montevideo, Uruguay
Hello how are you. Today I annoy them because I need help.
I always play with simulations in LTSPICE. I usually have simulations of phono preamps.
I need you to help me "copy and paste" a Laplace font for the inverted RIAA function.
I'm amateur and I can not do it.
Thanks friends of the forum.
  Reply With Quote
Old 9th February 2018, 12:02 AM   #3962
rjm is offline rjm  Japan
Richard Murdey
diyAudio Member
 
rjm's Avatar
 
Join Date: May 2004
Location: Kyoto
The Phonoclone and VSPS PCB Help Desk
You can cheat by setting up a little passive filter circuit to generate the inverse RIAA function. It's a simulation so you can make the output impedance as low as you want i.e. use super-low resistance values and ridiculously large capacitance.

I'd share but I don't actually use this myself. I take the output of the circuit using a flat voltage signal source and compare it in an Excel worksheet later with the reference RIAA curve. I've attached an example.

If anyone does know how to generate the inverse RIAA function directly in LTSpice using the transfer function, please feel free to jump in here - I'd also like to know how to do it.
Attached Files
File Type: zip Emerald RIAA response 40-60.zip (118.8 KB, 9 views)
__________________
RJM Audio website|blog
  Reply With Quote
Old 9th February 2018, 02:26 AM   #3963
ALPUY is offline ALPUY  Uruguay
diyAudio Member
 
Join Date: Mar 2012
Location: Montevideo, Uruguay
Thanks Richard. I am already using a passive circuit (Elliott's).
But I saw in the forum that just like Laplace RIAA can be simulated (Calvin gave me the formula to copy and paste) you can also simulate reverse RIAA.
Greetings, Josč.
  Reply With Quote
Old 14th February 2018, 06:43 PM   #3964
ALPUY is offline ALPUY  Uruguay
diyAudio Member
 
Join Date: Mar 2012
Location: Montevideo, Uruguay
Click the image to open in full size.

Click the image to open in full size.


Click the image to open in full size.

The formula of reverse RIAA with trial and error arose.
Where in RIAA was multiplied I put it divided and etc. (The formula of Laplace RIAA was given to me by Calvin)
I think it was fine, but I submit it to corrections.
Do not forget that I am a doctor, not an engineer.

Last edited by ALPUY; 14th February 2018 at 06:54 PM.
  Reply With Quote
Old 14th February 2018, 11:24 PM   #3965
rjm is offline rjm  Japan
Richard Murdey
diyAudio Member
 
rjm's Avatar
 
Join Date: May 2004
Location: Kyoto
The Phonoclone and VSPS PCB Help Desk
Could you upload the .asc file? It would save some time if you want me to check it against my reference.

It seems right, though you have the 4th time constant in there too unless I am mistaken.
__________________
RJM Audio website|blog
  Reply With Quote
Old 15th February 2018, 12:47 AM   #3966
ALPUY is offline ALPUY  Uruguay
diyAudio Member
 
Join Date: Mar 2012
Location: Montevideo, Uruguay
laplace((75µ*s+1)*(3183µ*s+1))/((318µ*s+1)*(3.18µ*s+1))/{10}

Richarg. I just play with LTSpice. What I thought was to base myself on the RIAA generator that Calvin gave me and modify in reverse. What multiplied it made it divide.
Therefore, the .asc file can not be found.
I show you the formula that emerged after the modifications.
  Reply With Quote
Old 15th February 2018, 02:12 AM   #3967
rjm is offline rjm  Japan
Richard Murdey
diyAudio Member
 
rjm's Avatar
 
Join Date: May 2004
Location: Kyoto
The Phonoclone and VSPS PCB Help Desk
Here's a simplified version.

Removing the Allen Wright 4th time constant, the laplace transform becomes,

laplace((75µ*s+1)*(3183µ*s+1))/((318µ*s+1))/{10}

Insert the transform between the voltage generator and the VSPS input and the circuit output is the gain multiplied by inverse RIAA response.

It's convenient for working out which circuit values give the most linear response. Note that is it not a simulation of the actual cartridge, as the output impedance of the coils is not modeled.
Attached Images
File Type: png vsps laplace.png (103.6 KB, 44 views)
Attached Files
File Type: asc VSPS.asc (3.6 KB, 2 views)
__________________
RJM Audio website|blog
  Reply With Quote
Old 15th February 2018, 02:50 AM   #3968
ALPUY is offline ALPUY  Uruguay
diyAudio Member
 
Join Date: Mar 2012
Location: Montevideo, Uruguay
Thanks Richard. I have made the modification.
Now to continue playing with LTSpice.
  Reply With Quote

Reply


The Phonoclone and VSPS PCB Help DeskHide 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

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 12:17 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki