Hi, I'm trying to understand these 2 EQP5s I built a little better. I'm swapping the filter caps to adjust the targeted frequencies, but I was also wondering, what are the rest of the capacitors doing functionally? I'm a bit if a newb and hoping to learn more about what components are swappable.

I'm currently looking at replacing the inductor for the high boost,  stock is 47mH, I'm going to try 86mH, 82mH and maybe the  low 150mH. My understanding is this will lower the frequency range of the boost shelf. But how is this calculated? How do I know which frequency range each inductor will hit?

Peterson, bless his soul, is going to send me some values for capacitors I can swap to modify the frequency ranges as well.

I read here about someone very excited by swapping out just the filter caps with some vintage units, but I've also read in other places that the newer capacitors work as well if not better than anything old or "retro".

Can anyone here school me on EQP mods and what matters and what doesn't? I've built a couple VP28's, an 1176, 2 EQP5s and a summing mixer, I can build this stuff but it's frustrating not really knowing how it works and how to make modifications to get them where I really want them!

For example: I see these big Wima caps on the right, what are they doing?  What's the function of the electrolytic capacitors on the right around the Wimas?

Photo of my current build (1 of 2) for reference.

Appreciate all you folks.


Re: Help with selecting capacitors and inductors for (DIYRE EQP5)
« Reply #1 on: August 04, 2020, 04:02:36 PM »
To calculate the frequencies, you can use this calculator: http://sim.okawa-denshi.jp/en/RLCtool.php
For the R just use the max value of the pot (10k), and the others are the capacitors (C) and the inductors (L). The frequencies are then calculated and displayed under cut-off frequency (note: most of them are not exactly spot-on on the unit, which is ok)

Re: Help with selecting capacitors and inductors for (DIYRE EQP5)
« Reply #2 on: August 05, 2020, 12:47:43 PM »
Thank you! I came across this as well: https://electronicbase.net/low-pass-filter-calculator/


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