Phono preamplifier. Active filter or pasive

[Hans Polak]

How so, RIAA is defined by a minimum phase polynomial in s, the time and frequency domain behaviors are not independent?

Some time ago I got strange results with this Laplace voltage source in the time domain that did not at all happen with an inverse Riaa network based on discrete R and C components.
When applying a Sinewave to a Phono amp through this Laplace source, there was an ever increasing phase shift between input and output that did not occur with the discrete Anti Riaa, and after some point in time even the amplitude from the Laplace source went down.
I reported this to Mooly, but never got an answer.

So I never use this Laplace implementation in the time domain, but in the frequency domain it works flawlessly. It's a perfect tool to check the linearity of a discrete Anti Riaa network.
When going to the time domain, I then use this discrete version, so I can live with it.
This experience was with LT SPice IV, I never tried LTSpice XVII.

Hans

 

[scott wurcer]

Some time ago I got strange results with this Laplace voltage source in the time domain that did not at all happen with an inverse Riaa network based on discrete R and C components.
When applying a Sinewave to a Phono amp through this Laplace source, there was an ever increasing phase shift between input and output that did not occur with the discrete Anti Riaa, and after some point in time even the amplitude from the Laplace source went down.
I reported this to Mooly, but never got an answer.

So I never use this Laplace implementation in the time domain, but in the frequency domain it works flawlessly. It's a perfect tool to check the linearity of a discrete Anti Riaa network.
When going to the time domain, I then use this discrete version, so I can live with it.
This experience was with LT SPice IV, I never tried LTSpice XVII.

Hans

I remember that, a software artifact. I use "noiseless" resistors VCCS connected back on itself and C's with VCVS buffers which works perfectly.

 

[Calvin]

Hi,

thats what I use as basic Sim params for RIAA
A VCVS with Laplace term, followed by a RL dummy pickup.
It allows to preset and change most parameters easy.

jauu
Calvin

 

[DouglasSelf]

Some time ago I got strange results with this Laplace voltage source in the time domain that did not at all happen with an inverse Riaa network based on discrete R and C components.

This experience was with LT SPice IV, I never tried LTSpice XVII.

Hans

I don't think you need to go into the Laplace domain to make an inverse RIAA generator. See Small Signal Audio Design.

I too have had silly results trying to use Laplace stuff, in my case in PSPICE, which is normally considered respectable. Much discouraged, I have never tried it on any other simulator.

 

[ALPUY]

Hi. Public video of Marantz PM6006.
Someone can identify if the phono preamplifier is discrete or IC; passive or active?.

https://youtu.be/_6q0ARZCuiY