Filter curve is slightly different

[waltercruz]

Hi! After trying to convert a bank, with the preset converter, I noticed that the filter curves are not exactly the same.

So I did a simple test: loaded a instance of Oberheim Sem V, and SEM-V2, and load Melda MMultiAnalyzer on each one. I tested the low-pass filter, and tried to match the sound of V2 to the same sound (frequency) of V1, comparing with MMutiAnalyser.

Not an exaustive test, but, for getting the same frequency output, the filters on SEM-V2 needs to be somewhat higher value than V1.

A quick table:

SEM V1	SEM V2
20	20
52	67
105	140
105	140
203	269
326	424
508	630
813	1004
1300	1556
1601	1889
2366	2715
3588	3994
4304	4728
5031	5463
6526	6950
8036	8425
9640	9969

11268

11616

I did a graph too:



I didn't test the other filter modes. It's a slightly difference, but when converting the presets, they don't sound the same (and it seems that the SEM-V converter doesn't convert the frequencies right anyway...)

[LBH]

Interesting. Thanks for testing.
Do you know the curve of the real hardware SEM?
Do SEM 1 or 2 curve come closest to the real hardware SEM?

[waltercruz]

Hi LBH! Don't know if it matches a SEM. Probably does. And I think that there's difference between SEM modules.

I think that it's ok, but some imported presets from V1 don't sound the same.

[LBH]

Hi waltercruz,

Thanks for your reply.

The original hardware had individual sound to a certain degree.

The fact that the new sound engines sound different than the old is for me to be exspected.
If i convert preset i will exspect them to sound more or less different.
That's also one of the reasons why i think VC4 should be bugfixed.

For me the important thing about the sound difference is, if the new engines are sounding closer to the originals as they are emulations. If they are, then the sounddifference is okay for me. But i'm not convinced about that.
If the applications both can sound like the originals and then add more, that's okay too. But a emulation is primarily to emulate the original.

Anyway - thanks for testing and sharing your results.


Best