Elliptical Filter Plugin

[DrDeltaM]

An elliptical filter is just a type of filter implementation, resulting in a very steep filtercurve, but with some ripple in the passbands. It doesn't do by itself what you are asking for however.

Mono summing under a centain frequency just means filtering S out under that frequency (as S dissapears on mono-summing). You can do this filtering with pretty much any type of filter, they just will have a different characteristic. So you can do this with any HPF and an MS matrix, or with a plugin that has those functions build in (shameless plug for my own DrMS plugin ).

[24-96 Mastering]

You have me confused now... Ls and Rs and Ms and S's are buzzing through my brain.

What I mean is that which on a vinyl transfer console is called an elliptical filter - to sum the bass to decrease groove width.

I.e. not to split to M/S and HPF S, but to take (below a crossover frequency) L and add it to R and to take R and add it to L so that low frequency signals that are panned far out still exist but in a phantom stereo source at respectively reduced amplitude.

I can build that by sending a track through a crossover and on the low signal adding L+R and R+L... but if there was a plugin to do that in one process, that would of course be easier and quicker...

[turtlerock]

i guess its not really a plug in but a while a go we bought up the last stock of jenson transformers passive lacquer blend units , basically a transformer with an passive eq circuit built in that gave taps at different eq points in the low freq range that were mono the top end all stereo . i think they were happy to see them go off the shelf after all those years

we get asked to do a lot of vinyl prep work that we then send to abbey road to get cut and i figured the less they have to do the better for everybody .

the neumann elliptical eq on the transfer console i used to use always left me wishing i could lower the freq just a bit on some tracks because it felt a bit high or then the low was a bit too low.
i would have bought a plug in that did this feature in 1 sec
it can sound really powerful - nothing to do with cutting disks as well

[jdg]

u can do this OK with ozone image tools.

[Adam Dempsey]

And watch your panned tom toms...

[Cellotron]

Originally Posted by DrDeltaM

An elliptical filter is just a type of filter implementation, resulting in a very steep filtercurve, but with some ripple in the passbands. It doesn't do by itself what you are asking for however.

Mono summing under a centain frequency just means filtering S out under that frequency (as S dissapears on mono-summing). You can do this filtering with pretty much any type of filter, they just will have a different characteristic. So you can do this with any HPF and an MS matrix, or with a plugin that has those functions build in (shameless plug for my own DrMS plugin ).

afaik the accepted definition for the Elliptical Equalizers that were manufactured since at least the 1960's for the process chains for the cutting of vinyl masters was a two band processor (often with 2 or sometimes more settable crossover frequencies) which summed to mono all frequencies below the crossover point. In other words the commonly used EE's such as the ones made by Neumann did not just remove the side channel bass frequencies but actually summed the Mid and Side channel together below the crossover point.

With many digital eq's that allow their bands to be set to process just the Side channel only it would certainly be easy to just remove the bass freq's from the Side channel - the Sonoris EQ and LPEQ's are both processors capable of easily doing this - Equalizer - Sonoris Audio Engineering

Otherwise a number of digital Elliptical EQ plugins are in fact available:
Brainworx "Control" has a control that's called "Mono Maker" -
MS-Mastering Tools by Brainworx-Media

as does their more expensive eq, de-esser and M/S matrix module - "BX Digital" -
MS-Mastering Tools by Brainworx-Media

GVST has a beta freeware VST plugin called "GMono Bass" - http://www.gvst.co.uk/dl070421/GMonoBass.zip

I'm sure there are others out there. It's fairly easy to set an EE up in a DAW with multing the file to two tracks, high passing one track, and low passing the second track and summing this track to mono. Having a single plugin that does this for you definitely makes this quicker to do though.

The one company I am aware of that still makes off the shelf hardware EE's is ADT Audio - their stuff looks really nice with tons of crossover freq choices - but it's pretty darn expensive - Niveau Filter with High Equalizer and elliptical EQ W794 or M/S Matrix with Stereo Base Width Control and Equalizer in the M/S Chain W731

Best regards,
Steve Berson

[polybonk]

The absolute best I have found is called monofilter by Nugen Audio. One of the best things in my kit IMHO.

[macc]

Voxengo Soniformer has this facility - you can draw/make your own width vs. freq distribution thumbsup

[DrDeltaM]

Originally Posted by 24-96 Mastering

What I mean is that which on a vinyl transfer console is called an elliptical filter - to sum the bass to decrease groove width.

Yes, I was talking about this: Elliptic filter - Wikipedia, the free encyclopedia

Originally Posted by 24-96 Mastering

I.e. not to split to M/S and HPF S, but to take (below a crossover frequency) L and add it to R and to take R and add it to L so that low frequency signals that are panned far out still exist but in a phantom stereo source at respectively reduced amplitude.

Adding L to R gives an M signal, as does adding R to L. So what you describe is placing an M signal at the left under a certain freq, and an M signal on the right under that frequency. Depending on the panning law, this is the same as just keeping an M signal and filtering out the S signal up to that frequency in an MS setup. The only influende the panning law will have is the volume of that M signal under the crossover freq. Something you could adjust yourself with an EQ on M for example.

[DrDeltaM]

Originally Posted by Cellotron

afaik the accepted definition for the Elliptical Equalizers that were manufactured since at least the 1960's for the process chains for the cutting of vinyl masters was a two band processor (often with 2 or sometimes more settable crossover frequencies) which summed to mono all frequencies below the crossover point. In other words the commonly used EE's such as the ones made by Neumann did not just remove the side channel bass frequencies but actually summed the Mid and Side channel together below the crossover point.

The origin of that name 'elliptical filter' for vinyl records probably has to do with the actual movement of the needle I guess.

[24-96 Mastering]

Ah, the mindgame that is M/S ... You're of course right, DrDelta. I work with M/S often enough, but as it turns out, my brain still works in L and R unless I concentrate.

DrDelta: What does this mean for the M signal below the crossover frequency with regards to panning law though? +3 dB? I am still somewhat confused...

--------------------------------------------

Still, having one quickly inserted plugin to check (that will also take care of panning law level change) would be nice.

Thanks for the suggestions, every one. While all suggestions look promising, of course, the first go to would be the most simple (and free) GVST. I'm not sure about level compensation though. Other than that, it seems to do what I want but it seems the slope is pretty mellow. Does anyone know what kind of slope a typical transfer console elliptical filter uses?

[Paul Gold]

Originally Posted by 24-96 Mastering

Does anyone know what kind of slope a typical transfer console elliptical filter does?

The two Neumann types are 6db/oct.

[DrDeltaM]

Originally Posted by 24-96 Mastering

DrDelta: What does this mean for the M signal below the crossover frequency with regards to panning law though? +3 dB? I am still somewhat confused...

That was to point out the possible difference between keeping only M (filtering out S) and filtering out S and placing M in both L and R. That can give a level difference, depending on the panlaw. But you shouldn't really worry about it, trust your ears.

I just use my DrMS plugin and use the HPF in the Side. Handy to make my own tools, as they work the way I want them to work

[24-96 Mastering]

Thanks Paul, great to hear information from the vinyl expert. And thanks DrDelta, and all the others for the information and the plugin suggestions. Very helpful!

[kjg]

Originally Posted by DrDeltaM

I just use my DrMS plugin and use the HPF in the Side. Handy to make my own tools, as they work the way I want them to work

That looks like an interesting plugin Mathijs. Congratulations on the release!

Just out of curiosity:
For the tilt and high pass filters, did you use objects from the standard Max/MSP distribution, 3rd party objects, or did you develop your own externals?

Also, are you running on 32bit float internally (standard Max/MSP), or on higher resolution custom code (like the hr.objects by JKC, or your own code)?

With kind regards,
Klaas-Jan Govaart

[kjg]

Originally Posted by DrDeltaM

Mono summing under a centain frequency just means filtering S out under that frequency (as S dissapears on mono-summing).

True. From my understanding, proper implementations of the two techniques (1: MS + Side filtering, 2: Crossover + LF summing) should have the exact same result.

To clarify for myself and others, I did the numbers (please correct me if I'm wrong):

1: MS + Side filtering technique.
For the sake of clarity I'm using equal gain MS matrixing with gain compensation in the decoding *

example 1: signal = 1, polarity = L+R+ (in phase), Left = 1, Right = 1

LR to MS matrix
Mid = (L + R) = (1 + 1) = 2
Side = (L - R) = (1 - 1) = 0

PROCESS. Pass Mid signal unaltered & HPF Side signal: Mid = 2, Side = 0

MS to LR matrix (including -6.0206 dB gain compensation)
L = 0.5 * (M + S) = 0.5 * (2 + 0) = 1
R = 0.5 * (M - S) = 0.5 * (2 - 0) = 1
result: Phantom image remains the same.

example 2: signal = 1, polarity = L+R- (out of phase), Left = 1, Right = -1

LR to MS matrix
Mid = (L + R) = (1 + -1) = 0
Side = (L - R) = (1 - -1) = 2

PROCESS: Pass Mid signal unaltered & HPF Side signal: Mid = 0, Side = 0

MS to LR matrix (including -6.0206 dB gain compensation)
L = 0.5 * (M + S) = 0.5 * (0 + 0) = 0
R = 0.5 * (M - S) = 0.5 * (0 - 0) = 0
result: Out of phase information has been removed by HPF.

2: Crossover + LF summing technique

example 1: signal = 1, polarity = L+R+ (in phase), Left = 1, Right = 1

PROCESS: Crossover signal, sum LF component, pass HF component unaltered:

Low band L = 0.5(L + R) = 0.5(1 + 1) = 1
Low band R = 0.5(L + R) = 0.5(1 + 1) = 1
result: Phantom image remains the same.

example 2: signal = 1, polarity = L+R- (out of phase), Left = 1, Right = -1

PROCESS: Crossover signal, sum LF component, pass HF component unaltered:

Low band L = 0.5(L + R) = 0.5(1 + -1) = 0
Low band R = 0.5(L + R) = 0.5(1 + -1) = 0
result: Out of phase information has canceled out by summing.

NOTE: A proper implementation of the crossover + LF summing technique does not output one mono signal (L+R) for the low band,
(as level in a stereo system will only be correct if the system uses a panning law of -6dB),
but instead outputs two signals 0.5 * (L+R), one for Left and one for Right.
(Which will result in correct levels no matter what panning law used.)

With kind regards,
Klaas-Jan Govaart




* Equal power matrixing (so the encoding and decoding matrix are identical) would be like this:

MATRIX
Mid or Left = 1/sqrt(2) * ((M or L) + (S or R))
Side or Right= 1/sqrt(2) * ((M or L) - (S or R))

Which would work out like this with the same signals:

example 1: signal = 1, polarity = L+R+ (in phase), Left = 1, Right = 1

LR to MS matrix
M = 1/sqrt(2) * (L + R) = 0.707107 * (1 + 1) = 1.414214
S = 1/sqrt(2) * (L - R) = 0.707107 * (1 - 1) = 0

PROCESS. Pass Mid signal unaltered & HPF Side signal: Mid = 1.414214, Side = 0

MS to LR matrix
L = 1/sqrt(2) * (M + S) = 0.707107 * (1.414214 + 0) = 1
R = 1/sqrt(2) * (M - S) = 0.707107 * (1.414214 - 0) = 1
result: Phantom image remains the same.


example 2: signal = 1, polarity = L+R- (out of phase), Left = 1, Right = -1

LR to MS matrix
M = 1/sqrt(2) * (L + R) = 0.707107 * (1 + -1) = 0
S = 1/sqrt(2) * (L - R) = 0.707107 * (1 - -1) = 1.414214

PROCESS. Pass Mid signal unaltered & HPF Side signal: Mid = 0, Side = 0

MS to LR matrix
L = 1/sqrt(2) * (M + S) = 0.707107 * (0 + 0) = 0
R = 1/sqrt(2) * (M - S) = 0.707107 * (0 - 0) = 0
result: Out of phase information has been removed by HPF.

[DrDeltaM]

Originally Posted by kjg

That looks like an interesting plugin Mathijs. Congratulations on the release!

Thanks!

Originally Posted by kjg

Just out of curiosity:
For the tilt and high pass filters, did you use objects from the standard Max/MSP distribution, 3rd party objects, or did you develop your own externals?

I didn't reinvent the HPF

Originally Posted by kjg

Also, are you running on 32bit float internally (standard Max/MSP), or on higher resolution custom code (like the hr.objects by JKC, or your own code)?

It is running 32bit float, I don't feel there was a need for anything higher.

[Alxi]

What about this ????

otiumFX :: Basslane VST

-Alxi-

[807Recordings]

Why can't you just use a phase pluggin like in samplitude or sequoia. I often track my moogs and stuff in stereo but might pull bass in frequencies that can go to mono for vinyl cutting. If I through a 250Hz mono filter over the whole mix it just looses that feeling and even sometimes I might have to hit a touch lower for some synths.

i don't usually mess with the rest as I leave that to the ME at The Exchange for the cutting.

[Yann Dub]

hello ,

I have schematics of the neumann EE filters , do you want them ?

I personaly do this that with a weiss eq1 or a TC finalizer 96k

[kjg]

Originally Posted by Yann Dub

I have schematics of the neumann EE filters , do you want them ?

I'd be interested to have a look!

[Bob Olhsson]

The down side of elliptical filters is that our sense of size comes mostly from out of phase low frequency perception.

[24-96 Mastering]

Originally Posted by Yann Dub

hello ,

I have schematics of the neumann EE filters , do you want them ?

I personaly do this that with a weiss eq1 or a TC finalizer 96k

Wow, thanks for the offer. That would be very interesting. Do you have them in electronic form?

[Yann Dub]

original neumann schematics , this model is used in sp 72, 75

But I realy think it is better you leave the cutting room doing it : it is difficult to know is it is realy usefull or not to apply this kind of filter before making a test cut .

Personaly , I do this kind of filtering when it is usefull to do it .

[24-96 Mastering]

Originally Posted by Yann Dub

But I realy think it is better you leave the cutting room doing it : it is difficult to know is it is realy usefull or not to apply this kind of filter before making a test cut .

I agree. For me, this is only for estimating / showing to clients that do a CD as well as vinyl what some of the differences on the vinyl cut will be in the end. So it's not for processing, only for monitoring / listening evaluation in advance.

[Yann Dub]

Give me some days to scan the schematics of the EE66
It has 2 frequencies you can choose :150 Hz and 300 Hz . Generaly it is use at 300 Hz and 150 is for Half speed cutting .

Neve did a different system caled vertical bass cut, you can t choose the frequency but the attenuation , 3dB , 6 or 9 .

I use both of them ( the neumann system in Paris and the Neve in brussels) , I prefere the sound quality of the neumann , the electronic is realy sinplest , but the features of the neve make than sometimes it is the good choice ...

Another way to do it , wich is probably the best one, if you have highend digital treatment is :
L R is going to a M/S matrice , you apply a high pass filter at 250 Hz of 6 dB per octave on the side channel , you rematrice M/S to L R .
A weiss eq1 is perfect for that , also one of the plug of the Finalizer 96K is very good , the 3 bands stereo imager .
With those settings you will have a filter wich is sounding very similar to the neumann . It can gives a good idea to your clients .
At the same time it can clear a lot the en of the spectrum and making it more "easy" to understand . so interesting even for digital ....

[baikonour]

Hello, I m bumping this thread as I have purchased a brainworx plugin to mono the bass of a recording for vinyl duplication and I would like to know from what frequency shall set the filter to? I know from previous posts that the Neumann filters are set at 300hz but is it the ideal crossover freq or is 250hz or lower?

Cheers

[mischa janisch]

Originally Posted by baikonour

Hello, I m bumping this thread as I have purchased a brainworx plugin to mono the bass of a recording for vinyl duplication and I would like to know from what frequency shall set the filter to? I know from previous posts that the Neumann filters are set at 300hz but is it the ideal crossover freq or is 250hz or lower?

Cheers

I'm not en expert for vinyl, but Elliptical EQs are problem solvers, so unless you have a problem - I would stay away from them and definitely not use them by default since I can't imagine that they will improve the sound - probably the opposite is true. Maybe I missunderstood your intention, but it sounded like you were going to use it just because you were mastering for vinyl...

To my knowledge - UNLESS a track has some weird stereo synth bass sound or contains other really out of phase material in the bass AND the vinyl needs to be cut really loud elleptical EQs are NOT in the chain when cutting vinyl.

But to answere your question: I'd use the lowest possible crossover freq - definitely not 300Hz @ 6db per octave...

[Bob Olhsson]

Originally Posted by mischa janisch

...To my knowledge - UNLESS a track has some weird stereo synth bass sound or contains other really out of phase material in the bass AND the vinyl needs to be cut really loud elleptical EQs are NOT in the chain when cutting vinyl...

That's my experience too. It's also system dependent.