Attention UAD users!

  • Thread starter Thread starter mshilarious
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mshilarious

mshilarious

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Do the UAD emulations sound exactly like the hardware? The debate continues, but not here!

One significant difference I have noted in the past was that no UAD plug I have tested (I have most of the pre-UAD-2 release plugs) generates any even-order harmonic distortion at all. Literally none. 0%.

Since that is the desired type of harmonic distortion, and second-order distortion is often the dominant type of distortion in a circuit, that's a serious problem if one is trying to emulate an analog circuit. It baffles me why UA didn't model that behavior.

Well, I can't do emulations, but I can help fix this problem. Even-order distortion is an asymmetrical distortion of a waveform; that is, it occurs to a different degree to the top and bottom of the wave. Whereas odd-order is a symmetrical distortion; that is the behavior that all UAD compressors exhibit (since they are compressing symmetrically).

So all we need to do is feed the plug a waveform with DC offset. The UAD plug will compress one half of the wave more than the other half due to the offset. Et voila, even-order harmonic distortion!

Note that this only works if the compression algorithm is not preceded by a high-pass filter, because the high-pass filter will remove the DC offset and spoil our plans. Fortunately, most of the UAD compressors don't seem to have that feature (which is odd if you are emulating an analog circuit, because most analog inputs won't pass a DC offset).

So I humbly present Simon, the ugly little runt brother to Nigel:

Simon

Simon is a .dll file that you will need to save to your VST plugs folder. It's very simple: one knob is DC offset from 0 to 1, the other knob is gain up to 100 (+40dB).

Place Simon in front of the UAD plug that you want to generate even-order distortion. I have verified that it works with the following plugs:

- Nigel (compressor must be active, recommended ratio of 4 or greater)
- LA2A
- LA3A
- 1176LN

It does NOT work with the Fairchild.

Anyway, by twiddling with the knobs in Simon and Nigel, you can generate a MUCH larger variety of overtones than Nigel itself can manage; forgive me for saying that I think it breathes new life into a plug that UA has abandoned. I recommend avoiding the Bent knob if you want clean and phat, it just adds high-order distortion. Select the Supa Clean amp model, keep Color and Bent low, set input Lows very low and make up the lows with the output Low knob, and you'll have a clean sound with very high second order distortion and almost no higher-order distortion.

Enjoy, and let me know about the UAD compressors I don't have, and any glitches you find! :)
 
I'll give it a try tomorrow. Is there any reason to remove the DC offset later in the signal path... after it has run through the compressors??
 
Chili said:
I'll give it a try tomorrow. Is there any reason to remove the DC offset later in the signal path... after it has run through the compressors??
Click to expand...

It needs to be removed before further processing; however, all of the plugs I tested removed the offset after compression. This could happen because the plug implements a filter somewhere after the compression algorithm, for example. But definitely, sticking a high-pass filter after any plug that doesn't internally remove the offset is a good idea--Precision EQ with the high-pass set on 10Hz will do the trick.

I realized last night I should have provided the ability to generate negative as well as positive offset, so I'll do that this morning.
 
I haven't tried it with Nigel yet, but I really have never used it before,either. I did try it with the 1176SE on a vocals track and didn't notice any difference. Maybe I shouldn't expect one if the Simon plug is meant to enhance a distortion plug.

However, the one glitch I noticed is a loud spike when I enable it it. Maybe a soft start might help to eliminate the spike.

So, umm, how do you make plugs?? Some developer's kit somewhere? Is it something the average laymen can do? Probably not...
 
Chili said:
I haven't tried it with Nigel yet, but I really have never used it before,either. I did try it with the 1176SE on a vocals track and didn't notice any difference. Maybe I shouldn't expect one if the Simon plug is meant to enhance a distortion plug.
Click to expand...

It's very dependent upon offset level as well as the output level into the plug. At the default Simon settings with a -12dB peak sine wave into the 1176SE default settings, I am seeing 1% THD at the second harmonic.

Now, as I said before I neglected to provide for negative offset. If you have a wave with a larger negative than positive peak (male vocals often have unusual assymetry), Simon wouldn't do as much.

That said, perhaps we could have a discussion on how much THD really matters. On a male vocal, the answer is probably not much. My voice has a stronger second-order harmonic than fundamental, and further harmonics that all exceed 1% of the fundamental. So how is an added 1% supposed to be audible? It probably isn't.

For higher amounts of THD with the 1176s, try the all-buttons mode with a fast attack and release--that allows the maximum wave-shaping possible. I am certain you will hear the difference between Simon on and off with those settings! Probably don't want to use that setting on vocals though! Maybe bass DI, that's what I usually use the 1176 for.

Similar on Nigel, you get more distortion if the compressor is set to fast; it also helps to use the Bright settings on the amps.

However, the one glitch I noticed is a loud spike when I enable it it. Maybe a soft start might help to eliminate the spike.
Click to expand...

Hmmm, yes, that is what a sudden DC offset will do. Have to think about that one . . .

So, umm, how do you make plugs?? Some developer's kit somewhere? Is it something the average laymen can do? Probably not...
Click to expand...

I use Synthmaker, it's lots of fun :) Obviously I put no effort into the GUI on this one; I tried a bit harder with Organ Monkey but honestly I don't really care about GUIs, mainly I wish the UAD ones took up less real estate. I suggested that to them one to no avail :(
 
Hey, I just noticed that in at least two situations, Nigel can generate even-order distortion on its own: the Custom Blues amp with the Compressor Boost on generates a lot and the Big Beaver and Gemini generate a little irrespective of other settings. Some of the other amps will generate a small amount, but often it's swamped by intermod distortion whose source isn't even apparent. But definitely, the Custom Blues is a useful model for even-order on its own. The Color and Bent controls will suppress even-order distortion as they are increased for the Custom Blues amp.

Still working on fixing Simon; I have a patch that should work but it doesn't work in Wavelab :(
 
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