boji

Parallel EQ-ing & aux fx insert spitballin'
« on: July 11, 2019, 12:40:10 AM »
Hello friends. Couple of noob questions I'd like to put to the gdiy braintrust?

Was doing a final bench run on channel logic / 500 slot connections, and I have serial inserts covered, but realized it would be very easy to add a parallel insert option too.  I know parallel compression is popular, but does anyone around here use parallel EQ in mix/tracking channels?  For my situation, both the 500 slot and input channel preamp have their own output tx's and would tie together at the channel fader in parallel with a simple mod.
Is this a no-no in a input channel? Something better left to a patch panel connection, as it is traditionally a mastering / group bus thing, or not a popular mixing/tracking technique?

One more question due to real-world console inexperience, if you don't mind...
Are there consoles out there that have fx inserts positioned such that you can toggle including/excluding them from hitting the auxes? I ask because I also realized adding this would be a simple matter of modifying where the aux prefade gets its input from-- post or pre 500 inserts.

Thanks for your opinion / advice in advance!
-Boji


fazer

Re: Parallel EQ-ing & aux fx insert spitballin'
« Reply #1 on: July 11, 2019, 01:45:24 PM »
I believe the ITI parametric is parallel within its own buffer amps and has a sweet hi frequency sound because of it.   And seems like a 550 is the same with input and output amps.  But back to your question the prefade no eq postfade eq,  seems more functional for live sound than for studio since you pull the mix from the multitrack output and you don’t have possible feedback problems like you might on a stage with two mixes.  Parallel compression is the main function and for that , having ability to use it on your 500 compressor modules.  Is quick way to have a yes/no decision.  My 2 cents .

boji

Re: Parallel EQ-ing & aux fx insert spitballin'
« Reply #2 on: July 12, 2019, 12:02:31 AM »
Quote
Parallel compression is the main function and for that , having ability to use it on your 500 compressor modules.

As added incentive, looked over the majority of standard 500 series comp/limiters and many do not have blend knobs, so I'll take the easy step of adding it. All I'd lose by omitting it is for a particular button state, switched-out opa in and tx out would sit idle on the patchpanel.  Thanks Fazer for the nudge!


ruairioflaherty

Re: Parallel EQ-ing & aux fx insert spitballin'
« Reply #3 on: July 12, 2019, 02:38:21 AM »
I believe the ITI parametric is parallel within its own buffer amps and has a sweet hi frequency sound because of it. 

Hmmm, Not parallel in the sense that we normally mean when we say parallel processing - a dry signal blended in some amount with a wet signal. They are parallel in that the filter banks are all wrapped in the same opamp feedback loop.

Also, if the ITI highs are sweet as you say, how do you know that it's the "parallel" nature of the EQ circuit that is responsible?  I've never used an ITI, only GMLs and quite a few Sontecs.  In the Sontecs at least I'd think the first order (cap only) nature of the shelf and opamp coloration are better bets for its sweetness.

fazer

Re: Parallel EQ-ing & aux fx insert spitballin'
« Reply #4 on: July 12, 2019, 05:12:19 PM »
The discrete amps in the ITI are one of the reasons for the hi freq sound quality but just comparing it to a serial chain eq bands, (feeding one into the next),  have ability to do drastic surgical eq but have had a metallic top end to me where maybe there running out of slew rate.  It could be other reasons as you suggest.  In Massenbergs  own description maybe from the original AES paper ,  he describes that he also played with state variable filters in series and did not like the sound as well as the design he used in the ITI that be came a parallel feedback circuit as you describe.   Later that became sontec and then Massenburg I’ve like topend better from parallel feedback eq’s.  IMO. 

That said your the mastering engineer.  Do you use eq in a parallel channel hookup? Or with a blend?  It was the original question from boji.

ruairioflaherty

Re: Parallel EQ-ing & aux fx insert spitballin'
« Reply #5 on: July 12, 2019, 10:19:51 PM »
The discrete amps in the ITI are one of the reasons for the hi freq sound quality but just comparing it to a serial chain eq bands, (feeding one into the next),  have ability to do drastic surgical eq but have had a metallic top end to me where maybe there running out of slew rate.

I dunno man, you're moving the goal posts again. I don't think there is one factor that makes a good design work, everything counts.  George and Burgess have long held that the speed of their opamps was a factor in the sound of the units, as far as I can tell it just made them more vulnerable to failure.

I'll leave it to the better minds here but I don't see how massively over speccing slew rate can bring anything to the table.

Quote
It could be other reasons as you suggest.  In Massenbergs  own description maybe from the original AES paper ,  he describes that he also played with state variable filters in series and did not like the sound as well as the design he used in the ITI that be came a parallel feedback circuit as you describe.   Later that became sontec and then Massenburg I’ve like topend better from parallel feedback eq’s.  IMO. 

That said your the mastering engineer.  Do you use eq in a parallel channel hookup? Or with a blend?  It was the original question from boji.

There's a lot of lore around the original ITI EQ, I wouldn't pay too much attention if I was looking for real engineering knowledge.

I use two analog EQs daily, one a heavily modified Porter with SVF in one feedback loop, the other a design by my friend Dave Collins with several filters in series. Both sound great.

I guess I'm fighting the idea that we should categorize EQs into serial or parallel, or that it in some way tells us something useful.  It seems to be something that started with plug ins.

Re: Parallel EQ-ing & aux fx insert spitballin' New
« Reply #6 on: July 12, 2019, 11:07:23 PM »
Generally speaking Id apply parallel processing with time domain effects ,series with EQ and distortions ,but sometimes a blend of mics off the same amp cab ( say condenser and 57 )can give you just the tone you want with eq's out .

What goes on under the hood of your EQ in terms of series or parallel is ,I suspect is a different question to what was asked  , interesting none the less , and good to hear from you Ruairi.
« Last Edit: July 14, 2019, 05:13:52 PM by Tubetec »


 

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