ron_swanson

Analyzing Pultec clone EQ build...
« on: August 28, 2019, 03:10:05 PM »
I just recently finished building a Pultec MEQ-5 clone build.

All seems to be working as expected, but hoping to have a closer look at the results from a testing / measurement perspective. 

I have an old Pultec manual that includes a page of what appears to be scope traces of the EQ curves.  (See attached)

How does one go about analyzing / measuring something like this?   This is my first EQ build, so apologies if my question registers on the noob scale.  Trying to learn more everyday...

Thanks in advance!

~ Greg


john12ax7

Re: Analyzing Pultec clone EQ build...
« Reply #1 on: August 28, 2019, 08:16:39 PM »
You need appropriate software that can do frequency sweep measurements.  REW and ARTA are two options.

alexc

Re: Analyzing Pultec clone EQ build...
« Reply #2 on: September 02, 2019, 12:21:06 AM »
REW has some quite good 'sweep' dataset visual-ising  capabilites, with historical traces etc     ...  once you have your basics setup, you can run repeated sweeps with 'stop motion' tweaking of your pultec controls with quite good accuracy  :)

It's my goto for that kind of thing ...  'R E W'  [room eq wizard' software audio analysis suite]
I ping therefore I am

ruffrecords

Re: Analyzing Pultec clone EQ build...
« Reply #3 on: September 02, 2019, 03:27:58 AM »
To measure EQ response with REW it is not necessary to do sweeps. Just use the white noise source and the RTA graph will be the frequency response.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


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

ron_swanson

Re: Analyzing Pultec clone EQ build...
« Reply #4 on: September 03, 2019, 12:36:05 PM »
Looks like REW is the path I need to pursue here...

Thanks for the replies!  Much appreciated!


~ Greg

alexc

Re: Analyzing Pultec clone EQ build...
« Reply #5 on: September 05, 2019, 04:24:21 AM »
Me too!     

thanks Ian    :)
I ping therefore I am

ron_swanson

Re: Analyzing Pultec clone EQ build...
« Reply #6 on: September 09, 2019, 02:53:14 PM »
Well, after downloading and installing REW, I'm stumped on how to actually proceed with testing.  Most of the documentation and online discussion I can find for REW is centered around taking room calibrations with a mic which is of no interest at this juncture.

After spending a reasonable amount of time trying this connection and / or that setting, I've got nothing to appear within the spectrum analyzer in REW.  I'm clearly missing something here.  I can get my laptop and / or my crappy electronics bench interface to display within REW and emit sound in the preferences setup, but that's about all.   I'm unclear about how this would be configured...

Do I use an external signal source (Pink noise?) connected to the EQ then into REW or is there some means of using REW's internal signal generator in some sort of loopback configuration or ?  I have a fairly complicated ProTools HD setup in my recording studio which rarely gives me any configuration challenges that can't be resolved quickly, but for some reason this task seems to be escaping me.

Can anyone offer a path for me to follow here?  URLs? Books? Other? Appreciate any help that can be provided.


ruffrecords

Re: Analyzing Pultec clone EQ build...
« Reply #7 on: September 09, 2019, 04:35:15 PM »
REW includes its own signal generator than can make sine waves, white and pink noise and some other stuff.

When you start REW go to Preferences. In the page that opens up select the sound card or interface you want to use. The next step is to press the set levels button. For this to work you need to loop back your sound card output(s) to the input(s). When the do the levels check you should see one of the input meters respond. if this works you are ready to go and you can close the preferences box.

Now open the RTA, still with inputs looped to outputs on your sound interface. Open the generator and set it to 1KHz sine wave and turn it on. Now in the RTA window you should see a 1KHz spike and various noise and junk. If you can get this far you are basically working.

Now undo the loop back and insert the device you want to test. Check you can still get the 1KHz signal on the RTA. If this is OK, go back to the generator and set the output to white noise. Back on the RTA you should now see a frequency response curve of the unit under test.

Cheers

ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


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


 

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