• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

RIAA in LTspice

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Hi all
I recently decided to have a look at the LTspice/switchercad simulation program. It was my first attempt to use a SPICE program and I was pleasantly surprised to see that is rather easy to get started.

I have now drawn a few RIAA schematics in LTspice and included an exact ANTI-RIAA network to check the accuracy of the RIAA components.
As an example I of a schematic an its frequency response I have attached a file (example.zip).

The example schematic and a few others are included in another attached file (RIAA.zip)

To view the schematics and run the simulations you will have to
download the LTspice/switchercad program. It is freeware and can be downloaded from www.linear.com/software/

Once you have the schematics it is easy to change component
values, change to other tubes or completely modify the circuits.

I hope this will be useful to some of you.

Torben

SORRY: I can't attach my files. Don't know why
 
LTSpice is all you need to do SPICE simulations for tube circuits, I have used it extensively for tube RIAA circuits. The correlation between simulation and bench testing for audio frequency response has been excellent, under 0.1dB above 50Hz, about 0.5dB below 50Hz.

Frequency response studies for global negative feedback loop stability, out to 10MHz or so, usually don't correlate so well since parasitic capacitances are hard to add to the simulation, the simulation usually performs better (needs less phase compensation) than the actual circuit.

RIAA frequency response studies can be done with linear models at the expected DC bias conditions (DC plate current, voltage). Attached is an example of a single common cathode stage with linear models for 6072/12AY7 and IR LED in cathode circuit.
 

Attachments

  • 6072cc1.zip
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