This is an electrical frequency response calculator for a phono cartridge connected to an audio system. Bellow is the equivalent circuit.

If you want to find out how this equivalent circuit is derived – please read the intro to our “Electrical Analysis” service.

You can use this tool to predict final system frequency response.

This tool can only generate electrical resonance of your cartridge. For this you just need to know electrical parameters of your cartridge. Some manufacturers have these parameters in their product datasheet and some don’t. Even then, they all are “ballpark” values as during manufacturing there will always be some errors.

You can absolutely measure them yourself – it is one of the simplest electrical measurements you can perform with an LCR multimeter. But buying one is not going to be cheap.

However if you order our “Electrical Analysis” service – you will get a table with exact measured values of your particular cartridge.

Here is an example report values. By putting these numbers to the above calculator, you should get a frequency response like below.

Now download this frq. response and name it graph_data_180pf.txt. This file is now your default electrical frequency response. Meaning it is already present in your full frequency response of a cartridge.

Install REW software and import (Ctrl+I) your full frequency response that you got together with your “Electrical Analysis” report. Usually it’s left_frq_(#order).txt for left channel and equivalent for right. You should end up with a workspace like above.

Make sure you select “All SPL,” then go to Actions → Trace Arithmetic. In the Trace Arithmetic tab, select A/B from the functions drop-down menu and click Generate. You will end up with a third graph labeled “A over B” just like in the example shown above. This “A over B” is now your final frequency response without 180pF||47kΩ loading and you will use it as reference to add other loading’s.

Go back to calculator and generate files graph_data_280pf.txt.graph_data_380pf.txt graph_data_480pf.txt by changing only loading capacitance (or resistance, or both if you like). Now import them into REW and this time choose “A * B” as arithmetic function.  By pressing “Generate” you end up with “A times B” graph.

At this point you want to rename this graph to something more specific like “left_frq_180pf” and it’s a good chance to check if everything worked as it should.

Deselect all other graphs, leaving only your full frequency response, “left_frq,” and the renamed “left_frq_180pf.” These two should align perfectly, which is expected since we first removed and then added back the 180 pF loading influence to the full frequency response.

If all went well, you can proceed to generate the rest of the “A times B” graphs by selecting different loading for “B” and renaming them accordingly.

By closing all imported files and leaving only generated data, you will end up with your workspace as shown above. “All SPL” now displays how the final frequency response of the cartridge will look like when different loading is applied.