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 »
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


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
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

ilfungo

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

dagoose

Re: Passive Mastering EQ
« Reply #144 on: December 07, 2017, 05:12:28 AM »
Any progress? Just curious  8)
Da Goose Music Mastering http://www.dagoosemusic.nl

ruffrecords

Re: Passive Mastering EQ
« Reply #145 on: December 07, 2017, 11:47:56 AM »
Any progress? Just curious  8)
I have just finished the PCB layout for the higher bands EQ boards. Expecting prototypes in a couple of weeks. I am about to start laying out the low frequency PCB now I know the Sowter inductor works as I expected.

Cheers

Ian
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

Re: Passive Mastering EQ
« Reply #146 on: December 09, 2017, 04:17:33 AM »
Any progress? Just curious  8)

Breadboard it? Hard to get a more simple circuit  :)

ruffrecords

Re: Passive Mastering EQ
« Reply #147 on: December 09, 2017, 04:33:06 AM »
Breadboard it? Hard to get a more simple circuit  :)

Oh, yes the breadboard has all five bands on it. I will take a pic later today and post it here.

Edit: Here is the pic showing all five bands connected (just a single frequency on each). The custom Sowter is on the far left.

Cheers

Ian
« Last Edit: December 09, 2017, 08:00:37 AM by ruffrecords »
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

alexc

Re: Passive Mastering EQ
« Reply #148 on: December 10, 2017, 02:23:36 AM »
Those are some pretty sweet curves  :)

I think I'd like to make a pair with those!
I ping therefore I am

warpie

Re: Passive Mastering EQ
« Reply #149 on: December 10, 2017, 10:53:46 AM »
Hi Ian, a bit off topic but what ELMAs are these?

"81-124n" ?

Am I reading correct? Are they 04 series and if so, what Torque?

thanks!
w


ruffrecords

Re: Passive Mastering EQ
« Reply #150 on: December 10, 2017, 11:26:23 AM »
Hi Ian, a bit off topic but what ELMAs are these?

"81-124n" ?

Am I reading correct? Are they 04 series and if so, what Torque?

thanks!
w

They are from ELMA's Uniselector range:

http://www.elma.com/en/products/rotary-switches/rotary-switching-products/product-pages/uni-selector-detail/

Part number US-B1-124N

Torque is 4 Ncm and they come with a right angle header so you can mount the directly to a PCB

Cheers

Ian
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

warpie

Re: Passive Mastering EQ
« Reply #151 on: December 10, 2017, 11:54:55 AM »
Thank you Ian! Although I don't quite understand the difference between these and their 04 series (other than the vertical PCB of course)   :)

Gold

Re: Passive Mastering EQ
« Reply #152 on: December 10, 2017, 01:48:20 PM »
Ian, 
If you wanted to mount switches off board for say a stereo ganged version would flying leads of a few inches be a problem?

ruffrecords

Re: Passive Mastering EQ
« Reply #153 on: December 10, 2017, 05:07:19 PM »
Ian, 
If you wanted to mount switches off board for say a stereo ganged version would flying leads of a few inches be a problem?

That should be fine. Unlike my other passive EQs, this one operates at a relatively low impedance so short runs to switches ought to be OK.

Cheers

Ian
www.customtubeconsoles.com
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'