ruffrecords

Re: Passive Mastering EQ
« Reply #140 on: November 14, 2017, 11:33:52 AM »
I have now carried out a range of tests on the low frequency end of the EQ using the custom inductor supplier by Sowter. Here are the results:

30Hz boost and cut:





I was initially concerned about the 30Hz boost only having a Q of 0.3 but the curve actually looks pretty good.

Here is 50Hz boost and cut:





60Hz





80Hz:





100Hz:





140Hz:





160Hz:





200Hz:





240Hz:





400Hz:





480Hz:





480Hz:





725Hz:





870Hz:





They all look good to me. I just need to find out why the actual boot/cut is not quite the expected value but this could be as simple as the load presented by the  Scarlett 2i2. Notice to cut is less affected than the boost because it is lower impedance. lastly here is a pic of the array of capacitors I used in these tests. As you can see some of them are quite big and a few cases needed three caps to get the right value:




Cheers

Ian


« Last Edit: November 14, 2017, 11:54:30 AM by ruffrecords »


ilfungo

Re: Passive Mastering EQ
« Reply #141 on: November 14, 2017, 12:13:33 PM »
Great!!!
which software have you used for this tests?

ruffrecords

Re: Passive Mastering EQ
« Reply #142 on: November 14, 2017, 01:01:46 PM »
Great!!!
which software have you used for this tests?
It is a free program called REW which stands for Room EQ Wizard.

https://www.roomeqwizard.com/

It has a lot of features for measuring rooms but it also has an excellent spectrum analyser that is great for audio measurements. Plus, it has a built in signal generator. For EQ measurements I set this to white noise and just check the spectrum to get the frequency response. It runs on Windows, Mac and Linux.

It can also measure distortion and noise. All you need is a decent audio interface to your computer. I use a Scarlett 2i2.

Cheers

Ian

ilfungo

Re: Passive Mastering EQ
« Reply #143 on: November 14, 2017, 05:38:49 PM »
Thanks!