MPowersynth Sawtooth issue / DC-Bias affecting maximum RMS

[Terrafractyl]

Hey!

So this has been bugging me for a while, and I did some tests a few weeks back to see if I was crazy or not, only getting around to posting about it now.
Please tell me if I'm doing something really stupid and missing something, but as I've just turned the main osc shape to Saw, disabled transform and everything else on the Osc tab, and disabled everything else in the signal path I don't know what else I could be missing...

My images clearly show all this with a slightly older verion (9.16) but I have just now tested this issue on v10.00 and it was exactly the same.

Basically the saw wave in MPowersynth has always given me grief and never sounded right to my ears. For ages I figured it was because I was missing something, and I just avoided making certain kinds of patches with this synth, now I am looking at it on an oscilloscope I'm starting to think that this is actually a bug.

I put MOscilloscope on an instance, of MPowersynth and one on Uhe's Zebra(just because its my other most used synth), I made each as 'inital' as I could (ie just sawtooth, nothing else in signal path)
and got this: (Zebra on the left/ MPowersynth on the right)



They are both playing the same octave, and it is quite low. I think it was C1, but still the bottom half of the waveform is quite dramaticly different!

This was noticably less of a problem the higher the note played eg:



But I'm pretty sure this is why I can't use Mpowersynth for Sawtooth basslines.

Any ideas?

[jmg8]

Which mode is the osc in? Normal or harmonic?

[ZentralmassivSound]

Ha, great topic! I also noticed this form of the sawtooth sometimes when exporting test waves. Still, it sounds perfectly the same as the other "real" sawtooth. I am puzzled by this, too.

[jmg8]

From the manual:

What you see is not always what you get! Say you want a rectangle wave and play a 440Hz tone(A4). You would expect the output signal to be a really quick rectangle wave, right? Wrong! If you would do that, and actually most synthesizers on the market do that, you would get the infinite number of harmonics. And, since you are working in say 48kHz sampling rate, the maximum frequency that can actually exist in your signal is 24kHz. So everything above it would get aliased below 24kHz, and there would be a lot of aliased dirt. The "good" synthesizers perform a so-called anti-aliasing. There are several methods, most of them require quite a lot of CPU or have other limitations. The goal is to remove all frequencies above the 24kHz in our case or in reality, it is more about removing all aliased frequencies above 20kHz - this means, that we do not care about frequencies above 20kHz, because we do not hear them anyway. But we will keep it simple. Let's say we remove everything above 20kHz. You already know that the
rectangle wave can be created using an infinite number of harmonics or sine waves. We removed everything above the 45th harmonic (20000 / 440) so our rectangle wave is trying to be formed using just 45 harmonics, so it will not really look like a rectangle wave. After some additional filtering (like DC removal), the rectangle wave may look completely different than a true rectangle wave, yet it would sound the same! Does it matter? Not really. You simply edit the shape as a rectangle wave and let the synthesizer do the ugly stuff for you. But do not check the output, because it may be very different than what you would expect .

[Terrafractyl]

The osc is in normal mode.

I have read and re-read the above quote from the manual, and that is all well and good.

but I came to this problem because I don't like the way the saw 'sounds'. Now that I am looking at it, I think this is not because of the superior quality of the synth(which it is by the way, thats why I want it to do everything I want it to!), but surely something else.

This is just not a proper saw wave on the bottom half of the waveform, and to me it sounds quite different.
Naybe it IS a matter of taste, but to me that is very odd, as no other synth I know of puts out a saw wave like that, and it takes away from an otherwise brilliant synth

[ZentralmassivSound]

Well I just checked Massive and Steinberg Retrologue, and their saw waveform looks pretty much the same as the MPS one. Alchemy looks similar but a little more "classic" sawtooth, Waves Element looks similar but even more sine-like. None of the synths actually produces the sharp sawtooth that Zebra has.

[jmg8]

Well I just checked Massive and Steinberg Retrologue, and their saw waveform looks pretty much the same as the MPS one. Alchemy looks similar but a little more "classic" sawtooth, Waves Element looks similar but even more sine-like. None of the synths actually produces the sharp sawtooth that Zebra has.

Yes, I have also just checked many synths including Synthmaster and a bunch of analogue emulations. Almost all looked the same as MPS. One of the modes in Synthmaster looked close but nowhere near as sharp as Zebra.

I don't think that MPS saw sounds bad, so not really an issue for me, but it is interesting.

[MeldaProduction]

Ok, so as explained in the help - if you would create a shape exactly like sawtooth, it would NOT sound like sawtooth! Well, it would, but only in extreme samplerates, like 10MHz . So if a synth creates such a wave, then it is actually bad . Anyways try set Quality to Low and it should get close to that. But you know, that's low quality .

[Soundplex]

Does this mean MPowerSynth cuts off all above the 45th harmonic in general or does it take the played note into account?
What I'm trying to ask is: if the played note is (like in this example) about 30Hz it could have more than 600 harmonics to make a sawtooth looking (and sounding!) like the Zebra one. But MPS doesn't. So where does it cut off the overtones? And wouldn't it be low quality like it is now?

[MeldaProduction]

I'm not sure what you are doing and how, but my guess is that you have a filter engaged . Here's a saw wave from MPS, default settings... crystal clear "analog" thing ...

MAnalyzer01.png

[zerocrossing]

You want to hear a really bad sawtooth? Go buy a Prophet 12. It really bothered me. MPowersynth was one of the first synths I went to when I did a raw oscillator comparison and regardless of what I saw on scopes, it sounded great to me. I usually run it at 3x over sampling. Sold my Prophet 12. Kept MPowersynth.

[Terrafractyl]

INTERESTING!
So for the sake of argument, my three different analog modular oscilators all show up on scopes looking exactly like a sawtooth, I know thats different, but still (in an ideal world).

but in digital land after doing some more tests:
Reaktor looks like I would expect
So does Serum
So does Sylenth
and as mention before so does zebra2, so I assuming the other uhe synths also.

They all sound right to me.
Mpowersynth just doesnt.

Are all those other synths 'wrong'??

I will do some more investigations, but the main reason I came to do any tests in the first place is that I just can't seem to use MPowersynth for saw based patches. Especially bass lines. It just sounds wrong to me, and its not like I havn't been playing around with synths for 20 years, both analog and digital.

If that is by design then I guess I just have to keep on using other synths for that stuff....

In your help posted in the manual, to me it sounds like you are talking about bandlimited oscillators no?
I guess not as you say it is different from all digital synths on the market.
I love the sound of the synth, but I guess when it comes to saw waves I just can't agree with the 'sounds better than both analog and digital' statement, when to me everything else I have sounds better.

Im starting to think Dc filtering or Removal is perhaps one of the reasons. Maybe Mpowersynth is a bit more heavy handed with these than the others...?
sorry for all the questions!!

[Terrafractyl]

Also I just tried playing around with the quality mode on Mpowersynth, even though I was sure I had already tried this.
Putting it on Low quality mode, made no difference to the shape of the bottom half of the saw, it is still all skewed.

And again, I'm really not trying to pick on MPowersynth! I really love this synth, but I'm am really curious as to why I don't like the sound of the Saw, and I can't stress enough that it is the sound that bugs me. The images on scopes just seemed to co-incide with my own problems.

I don't have massive installed, which is a pity because I can't find another synth on my system that puts out a sawtooth that looks like this!

[Terrafractyl]

Also? sorry i have a lot of questions

When waveforms are lopsided and look like this, Isn't there is actually a waste of low end energy? as half the waveform is not pushing the speakers(or in this case woofers) as far as they can in both directions.
The reason I ask is I master a lot of music where one of the main elements (the bassline) is always a saw, and to me starting with such an assymetrical waveform like this before putting it though filters and eqs etc etc, is going to cause a lot of headaches down the track when trying to push the compression levels and get everything up to the desired RMS level.

[Terrafractyl]

Well I just checked Massive and Steinberg Retrologue, and their saw waveform looks pretty much the same as the MPS one. Alchemy looks similar but a little more "classic" sawtooth, Waves Element looks similar but even more sine-like. None of the synths actually produces the sharp sawtooth that Zebra has.

Yes, I have also just checked many synths including Synthmaster and a bunch of analogue emulations. Almost all looked the same as MPS. One of the modes in Synthmaster looked close but nowhere near as sharp as Zebra.

I don't think that MPS saw sounds bad, so not really an issue for me, but it is interesting.

Really? I wonder why you are a looking at analog emulations though? I don't think MPowersynth is trying to be one.
But regardless I'm looking at synthmaster now after downloading the demo.
I get this:


which is not 'quite' as sharp as Zebra, but very close, and it still looks like a saw shape on both sides.

Reaktor 6




Serum


and again MPowersynth (on the right)


I dunno, I guess I'm just surprised a) how different it is to everything else. b) no one else is bothered by it!