You are here

Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

For everything after the recording stage: hardware/software and how you use it.

Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

Postby samuk » Wed Mar 11, 2020 5:07 pm

I have two questions:

1. Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ unit, or are there issues this will cause?

2. If the above approach doesn’t work, will another of the same unit work - or can it only be done with a factory matched stereo pair with a stereo link?


I’ve learnt that this method doesn’t work with compression as it’s likely to lead to left-right image movements (see post here: https://www.soundonsound.com/forum/view ... 500&hilit=)

But will it work for EQ in the way I’ve described? Hugh Robjohns said it would be workable for a static process such as EQ, but what are the potential issues in doing this, if any?

If it doesn’t work, then would buying a second EQP-WA unit work? There’s no stereo link on the EQP-WA, but it does have a ‘Tube Gain Adjust’ control on the rear of the unit which the manual states ‘will allow users to match two units for stereo use’. Will this work? I am dubious as I’ve read regarding other units need to be identical factory matched pairs.

If all else fails I’ll just have to use plugins and maybe get a stereo outboard EQ at a later date.

Thanks for any advice.
samuk
Poster
Posts: 22
Joined: Tue Jan 08, 2019 3:32 pm

Re: Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

Postby The Elf » Wed Mar 11, 2020 5:28 pm

Since EQ is a static process then it should work better than dual mono compression, but I would encode to mid/side first (and decode back to L/R stereo on return) to remove any potential for L/R imbalance.

But I would also question whether this particular eq is genuinely so very special that you really want to do this?
User avatar
The Elf
Jedi Poster
Posts: 13706
Joined: Tue Aug 14, 2001 12:00 am
Location: Sheffield, UK
An Eagle for an Emperor, A Kestrel for a Knave.

Re: Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

Postby MOF » Wed Mar 11, 2020 5:39 pm

It should be fine, just make sure that the two mono files line up perfectly with the original stereo file, zoom in to sample level to check.
MOF
Frequent Poster
Posts: 659
Joined: Thu Mar 06, 2003 1:00 am
Location: United Kingdom

Re: Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

Postby Hugh Robjohns » Wed Mar 11, 2020 6:06 pm

samuk wrote:1. Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ unit, or are there issues this will cause?

Yes, you can. This has been discussed very recently, as you are well aware. It's not ideal... but it can be made to work in all circumstances, as was explained. Consider MS processing rather than LF to minimise obvious image shifts due to mismatches.

2. If the above approach doesn’t work, will another of the same unit work - or can it only be done with a factory matched stereo pair with a stereo link?

Any significant inaccuracies in settings between channels will result in image shifts. Stereo-linking only applies to dynamics processors, not EQs. Stereo EQs use ganged controls to try and ensure matched parameters between channels -- usually 0.5dB or better is the requirement. If you think you can match settings on separate hardware units to that level of precision then there's no problem -- and you can with most, althogh switched controls (as on mastering units) are obviously far easier than continuous rotary controls.

Hugh Robjohns said it would be workable for a static process such as EQ, but what are the potential issues in doing this, if any?

Time consumption and general faffing about!

If it doesn’t work, then would buying a second EQP-WA unit work?

I remain somewhat ducious about WA produts because of experience with production consistency -- which is precisely why they've added that tube gain trim facility. So if you use two separate units tyou will need to ensure they are properly gain-matched (for all settings) to avoid image shifts.

H
User avatar
Hugh Robjohns
Moderator
Posts: 26258
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Can I split stereo files into L and R channels for hardware processing through a mono outboard EQ?

Postby samuk » Wed Mar 11, 2020 10:23 pm

Thanks very much for your replies! Really helpful.

I now understand the issues and will try mid/side processing and check carefully for any L/R imbalance. I shouldn’t need to ask any more questions on splitting stereo files into L/R again!

The Elf - thanks for your advice. I do really like the EQP-WA, and subjectively it seems to add something to the sound when I run signals through it. There’s a sheen and sparkle to the top end, and bass sounds really good through it also. I am fairly new to mixing and very new to outboard, so it could be some bias I’m not aware of. There’s more presence and body to the sound to my ears however, and it sounded better to me than the plugin Pultec EQ’s.
samuk
Poster
Posts: 22
Joined: Tue Jan 08, 2019 3:32 pm