Old 01-23-2020, 05:20 AM   #1
jrk
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Default Fake Dolby A trick

Want that 70's sheen on yr stacked backing vox? Don't have one of the excellent (paid) plugins to do the job?

Try this (fx chain - two instances of ReaXcomp)

[edit] V2 down below, after my telling off from pipelineaudio (tweaks the band gains, adds some pre-emphasis)
Attached Files
File Type: rfxchain FakeDolbyATrick.RfxChain (740 Bytes, 92 views)
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Last edited by jrk; 01-31-2020 at 08:20 AM. Reason: updated
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Old 01-23-2020, 07:18 AM   #2
vdubreeze
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As in recording with dolby A and playing back without it? I'm in
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Old 01-23-2020, 07:28 AM   #3
jrk
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Quote:
Originally Posted by vdubreeze View Post
As in recording with dolby A and playing back without it? I'm in
Yep, it's an approximation of the top two bands of the Dolby A encoder (very approximate but it seems to work)
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Old 01-23-2020, 07:40 AM   #4
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Kewl! I have to give this a try on a couple of track s I have with multi BVs on them!

Nesxt thing you know I will be growing out a Mullet as welL!
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Old 01-28-2020, 11:07 AM   #5
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The free (though 32 bit) Storm Recording Studios exciter.

The Mutt Lange booster is a critical part of every mixd I make and lately I have switched to Audio Assault's version, XCTR is the one I use now
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Old 01-29-2020, 08:11 AM   #6
jrk
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Exciters and (multiband) saturation do something rather different tho. They're adding harmonics that weren't there in the original signal. Don't get me wrong, really useful sometimes (but *really* easy to overdo). I'm fond of "Roth-Air" http://www.danielrothmann.com/#downloads

For a lot of things, particularly if you're after a "period" sound, something like the Dolby A trick works well - might be a bit subtle unless you drive it fairly hard.
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Old 01-29-2020, 10:39 AM   #7
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Iíve got a project right now dude gave me a CD of a tape of a live performance complaining that itís all weak in the bottom and harsh in the treble. I donít know anything about how it was treated at any step of the way. I dicked with it for a half hour or so before it hit me that this was exactly what happened. In this case I donít think it even occurred to them to decode. Like I donít think they even knew it was a thing. I was able to hack together a decoder in Reaper in minutes and it really made all the difference.

Thereís another sounds almost like they did the opposite - recorded without encoding and played back with decoding on - but itís also actually damaged and kind of redundant. Trying to re-encode after the fact doesnít turn out so well.
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Old 01-29-2020, 11:03 AM   #8
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I've worked on old recordings before that, in short, sound closer to what the source (pre destructive transfers) would have sounded like with the dolby not decoded than with the hardware circuits decoder in the deck. With all the variables of the high end attenuation damage and everything else, some of the dolby eq boosts done on the way in ended up preserving some of the content a little stronger. Seven wrongs making a right of sorts. And even when there are artifacts breathing around from the dolby encoding moving the dynamics around in that scenario, it still might be closer to what the original recording might have sounded like than the wool blanket covered result the decoder would give.

I've used parameter modulation with ReaEQ in Reaper to try to simulate the decoder where dolby moves the crossover frequency keying off the source.
It's always tricky and case by case though. I don't feel like I have created a universal dolby decoder that I can just plunk down in any project and just push a button. Maybe this speaks to the damage in the recording and why the hardware dolby is also struggling? I still think I'm missing something at the same time though with the decoding technique.

A tape that someone already digitized to 16 bit CD and presumably with a budget interface (or maybe even worse with a circa 1990 CDR recorder or DAT deck with shit AD stages) is most unfortunate. The transfer in those examples incurs more loss than the tape format itself caused. Stuff you might have been able to work with or repair was left on the cutting room floor in the AD transfer.
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Old 01-29-2020, 11:39 PM   #9
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Quote:
Originally Posted by jrk View Post
Exciters and (multiband) saturation do something rather different tho. They're adding harmonics that weren't there in the original signal. Don't get me wrong, really useful sometimes (but *really* easy to overdo). I'm fond of "Roth-Air" http://www.danielrothmann.com/#downloads

For a lot of things, particularly if you're after a "period" sound, something like the Dolby A trick works well - might be a bit subtle unless you drive it fairly hard.
Audio Thing's Type is is EXTREMELY accurate to a modded Dolby A (you didnt just NOT decode, you normally would bypass the lower bands).

However, I will bet dollars to doughnuts that you will get the same results with XCTR and then you can go past that as well.

Both processes add harmonics, Dolby A is a nonlinear process
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Old 01-30-2020, 01:53 AM   #10
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Quote:
Originally Posted by pipelineaudio View Post
However, I will bet dollars to doughnuts that you will get the same results with XCTR and then you can go past that as well.
And I bet you're wrong, but seeing that you made the claim it would be up to you to prove it.

Quote:
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Both processes add harmonics, Dolby A is a nonlinear process
Well, this is plainly wrong since, if it were, it wouldn't be decode-able - which of course it is - to an acceptable value for "decode-able"

Anyhoo, you seem to be missing the point, which is that it's possible (nay, trivial) to make an *approximation* of the "Dolby A trick" using only stock Reaper fx. If you prefer multiband distortion or an enhancer, go for it. If you prefer to buy a plugin that more closely models Dolby A - do that.
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Old 01-30-2020, 03:49 PM   #11
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Of course Dolby A is a non linear process.

From someone who spent a VERY VERY long time trying to be happy with Dolby alternatives on the computer (which you can see from the very first few posts on this very forum), where instead I had to patch my hardware in, it may behove you to have a listen to these pieces of software we have found and some of us have completely replaced our Dolby hardware with
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Old 01-31-2020, 07:22 AM   #12
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Quote:
Originally Posted by pipelineaudio View Post
Of course Dolby A is a non linear process.
Overall, end-to-end, a noise reduction system is designed to be a linear process. Since Dolby A is based on (multiband) compansion, granted, for each band it's only linear above and below the threshhold(s). Correctly calibrated of course, this function is mirrored in the decoding. Thus the overall transfer function is (very nearly) linear.

I have trialled Audiothings "Type A" and found it to be excellent. As it happens, it does produce a tiny bit of odd harmonics, but something like 96dB down relative to signal. I'm not convinced that this will contribute to the subjective effect.


[EDIT] I was wrong (what you get for putting a 1kHz tone through something) in the area covered by the top two bands 3rd harmonic goes up to -60dB relative to signal. Hmm, not a lot tho' is it?

Quote:
Originally Posted by pipelineaudio View Post
From someone who spent a VERY VERY long time trying to be happy with Dolby alternatives on the computer (which you can see from the very first few posts on this very forum), where instead I had to patch my hardware in, it may behove you to have a listen to these pieces of software we have found and some of us have completely replaced our Dolby hardware with
I'm very glad that after years of searching you've found fx that satisfy you. However, this behoves me to do nothing.

I'm not saying that it's trivial to make a *exact copy* of the DolbyA top 2 bands with nothing more than a couple of ReaXComp. Or that you shouldn't have bought the plugins. But it is possible to get *something like the effect* thisway. One might tweak the gains on the two (overlapping) bands, maybe even add a bit of pre-emphasis. It's certainly not quite so plug and play.

Here's V2

Cheers.
Attached Files
File Type: rfxchain FakeDolbyATrick_V2.RfxChain (1.1 KB, 32 views)
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