Parallel eq

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I believe Mr. Clean [ Massenburg ] felt it was cleaner to do it that way , so there wasn't 4 or 5 filters affecting the entire signal
but that there was a limited amount of boost possible,
and if I'm not mistaken he also preferred to not balance outputs  [ to avoid the extra circuitry ? ]  the Stephans tape machines
were also unbalanced on purpose I believe .  I'll see if I can find some reference on the ol interweb .........
 
okgb said:
I believe Mr. Clean [ Massenburg ] felt it was cleaner to do it that way , so there wasn't 4 or 5 filters affecting the entire signal
but that there was a limited amount of boost possible,
and if I'm not mistaken he also preferred to not balance outputs  [ to avoid the extra circuitry ? ]  the Stephans tape machines
were also unbalanced on purpose I believe .  I'll see if I can find some reference on the ol interweb .........

You are confusing balanced with differentials, I'm with him in the non differential, balanced output. I think it's the best non floating method to drive the outputs. The limitations I see are level (6dB lower than a differential with the same rails) and it isn't a floating output. I can live with both I guess, going to a differential input it does matches the impedance so a very good CMRR is archived so as any little difference in reference potential is presented as common mode noise it's cancelled out. Going to an unbalanced input (I don't see a scenario where you'd do that with a GML gig) it works fine, only signal present in the proper line, no signal current being dropped to ground, you have the output resistor to add in series to the reference conductor just swapping a contact in the wiring to limit the current through the shield. A truly floating output would work better in this case but I just don't see the point of the extra beams only for when it's used with unbalanced equipment far enough to have a noticeable chasis voltage difference.

About the filters and parallel EQ, filters inside an eq are fine to be in parallel, is a well known application with known limitations and advantages. I wouldn't use an EQ in parallel by itself unless looking to explode its nonlinearities, you end up needing more extreme actions to archive the same effects making the internal signals more extreme, affecting the dynamic range, making it easier to add noise and distortion. It's reasonable to use eq in either (or both) side of a parallel compression independently to archive certain effect.

JS
 
ln76d said:
Ok, so what we talk about?
I think that the best would be if the autor of the topic will give the answer :D

As example of parallel filters in EQ units in 3D

http://www.khstudio.us/DIY%20PICs/3D%20EQ%20-%20FULL.bmp

Filters are connected in parallel and they go to the sum.

There's is no direct signal in parallel to the filters so my guess is that there is some misunderstanding of topic ;)

That's basically what's in the Rane PEQ-15 and -17 and every other parametric you'll see.

-a
 
ln76d said:
gyraf said:
No. You'd still get the exact same time-domain response.

Always when am processing track with analog eq it is delayed in comparision to the original track. Amount of the delay depends on amount of equalization.

Are you saying that you're mixing with a DAW and you've "inserted" an outboard analog EQ on a track? Of course you'll have latency on both the DAC out and the ADC in. Doesn't the DAW have a feature which compensates for that latency?
 
Andy Peters said:
ln76d said:
Ok, so what we talk about?
I think that the best would be if the autor of the topic will give the answer :D

As example of parallel filters in EQ units in 3D

http://www.khstudio.us/DIY%20PICs/3D%20EQ%20-%20FULL.bmp

Filters are connected in parallel and they go to the sum.

There's is no direct signal in parallel to the filters so my guess is that there is some misunderstanding of topic ;)

That's basically what's in the Rane PEQ-15 and -17 and every other parametric you'll see.

-a

"All" the parametric EQs i designed over a few decades were in series. 

Running EQ sections in parallel can lead to unintended interaction between frequency bands.

That said it is fairly common to run GEQ filter sections in parallel because they use fixed bandwidths and centers.

JR
 
I think we're messing up concepts a bit here.

My understanding of OP's question is that it was about parallel/blend-in type Eq'ing. Which imo makes no sense, other than for marketing.

An entirely different discussion is about EQ topology, i.e. how filters are arranged internally: We, in Gyraf Audio, make a device named Parallel-Passive Equalizer - this does NOT imply blend-in, but simply that the filter bands are all acting in parallel. In our case, the benefit is much more predictable impedances vs. frequencies - making the job simpler for L/C/R type of individual bands.

Jakob E.
 
gyraf said:
I think we're messing up concepts a bit here.

My understanding of OP's question is that it was about parallel/blend-in type Eq'ing. Which imo makes no sense, other than for marketing.

An entirely different discussion is about EQ topology, i.e. how filters are arranged internally: We, in Gyraf Audio, make a device named Parallel-Passive Equalizer - this does NOT imply blend-in, but simply that the filter bands are all acting in parallel. In our case, the benefit is much more predictable impedances vs. frequencies - making the job simpler for L/C/R type of individual bands.

Jakob E.

Jackob that is correct. The OP was all about the idea of a blend but in place of the usual of parallel compression  doing an eq.  I have had some engineers of late tell me that how it's amazing, etc, etc. Where as I am looking at it like I see no real point to doing such a thing.  So I was asking the brain trust their take on the matter...
 
Wall of guitar sound?
I personally haven't ever used parrallel eq but it might create an interesting effect on distorted guitars during a chorus.
I've definitely used parallel compression to achieve this effect (as I often use comps as eq's) but really I'm just trying to make sense I f when it would be applied and thats alk I could come up with.
Someone else mentioned "like a mojo box" which  seems the most viable.
 
pucho812 said:
well this came up  as I had people swearing that running an eq in parallel sounds better then as a normal eq in series.

While I have seen units that internally do parallel filtering(massive passive comes to mind) I was wonding about running the unit in parallel vs as a standard in series kind of thing.  For me I just do not see a real benefit to running it as a parallel process but hmmmm will have to further investigate.
In theory it is pointless. As others have said, it is just like using less cut and boost than you dialled in if there is also a parallel non-EQ'd path.

In practice, there may be oddities which have an audible effect. Non-linearities as already mentioned, which may be stronger due to needing higher boost and cut settings to achieve the same overall cut and boost. Also, a real outboard analogue EQ quite possibly has a non-ideal HPF and LPF even on its flat-setting bandwidth. If the parallel non-eq path has a better bandwidth then you'd hear a difference due to the extreme highs and lows being less rolled off. The EQ will have an albeit tiny group delay which would cause an unintended EQ effect on the super highs when combined with a parallel, non-delayed version of the same signal. The more interested speculator might run some figures to see if that last suggestion might actually be in the audible range.
 
The EQ will have an albeit tiny group delay which would cause an unintended EQ effect on the super highs when combined with a parallel, non-delayed version of the same signal.

I'm pretty sure that time-domain would be exactly the same, if you dial in the same setting without parallel. Think of the group delay being the other side of the "EQ coin", they always co-exist in a fixed pattern. Only exception is in digital, where you can do tricks to the timedomain, and get lin-phase - but with some strange artefacts added in time...

Jakob E.
 
gyraf said:
The EQ will have an albeit tiny group delay which would cause an unintended EQ effect on the super highs when combined with a parallel, non-delayed version of the same signal.

I'm pretty sure that time-domain would be exactly the same, if you dial in the same setting without parallel. Think of the group delay being the other side of the "EQ coin", they always co-exist in a fixed pattern. Only exception is in digital, where you can do tricks to the timedomain, and get lin-phase - but with some strange artefacts added in time...

Jakob E.
I looked up some figures. We're talking picoseconds of delay, even with a lot of cascaded circuitry, so the delay would not cause any significant effects in the audio band. I grasped too far looking for mechanisms to give a different sound to parallel EQ!
 
The only place I've seen it useful is with extreme sound effects filters with big resonant corners.  Too extreme to use by themselves. 

Dolby 740 is a reverse dynamics processor, turns up low level signals, leaves anything above the threshold alone.  Internal parallel processing with dry, has a crossover type EQ on the dynamics path for tailoring.  Doesn't really apply to this discussion. 
 
Matt Nolan said:
gyraf said:
The EQ will have an albeit tiny group delay which would cause an unintended EQ effect on the super highs when combined with a parallel, non-delayed version of the same signal.

I'm pretty sure that time-domain would be exactly the same, if you dial in the same setting without parallel. Think of the group delay being the other side of the "EQ coin", they always co-exist in a fixed pattern. Only exception is in digital, where you can do tricks to the timedomain, and get lin-phase - but with some strange artefacts added in time...

Jakob E.
I looked up some figures. We're talking picoseconds of delay, even with a lot of cascaded circuitry, so the delay would not cause any significant effects in the audio band. I grasped too far looking for mechanisms to give a different sound to parallel EQ!
I don't think it would be useful but there are a number of different EQ topologies that have subtle different phase behavior around their center frequencies. Placing different topology EQs in parallel at roughly equal level (both -6dB), I can imagine interactions different than a simple sum of the two amplitude responses.

But so what? EQ at it's best can completely correct amplitude and phase of natural errors. Making it less predictable, seems less than ideal.

JR
 

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