Fixed hidden negative loudness keytrack on analogs ?

[Mutant]

Hi everyone.
Recently when trying to match some hardware with my freeware software i noticed that to make the low notes shoot through the highs like most hardware synths do, i need to set my software synth to keytrack volume by around -10%.
On soft synths that can't keytrack volume, the low notes are usually not as powerful as on real analogs.
It is kinda possible to fix it with an EQ, but it is not the same because low notes can have high frequency content too, so only boosting the low frequencies wont work as good as boosting the whole spectrum of the low note.

I don't have any analog synths, so i can't check it.


So the question(s) is:
Is the loudness of low notes higher than the loudness o high notes on your >>polyphonic<< analog synth if the filter is 100% open ?
Should be pretty easy to check.
And if yes:
If you have some electronics knowledge and know how your synth is built from looking at the schematic, is that hidden loudness negative keytrack "an accident" or did the designers intended it to work like that ?

[Mutant]

Come on !
Hit that low note, look at the RMS/peak meter, hit the high note, look at the RMS/peak meter.
Lets do science !
Hmm... or maybe no one here has a real analog ???

[JCJR]

Its been a long time ago and those brain cells are mostly dead. Some synths did not have filters that could linear track good enough to for instance play a melody with them-- Set the filter resonance to self oscillation, with no vco input, and turn up the keyboard control voltage to full tracking, and play a filter sine wave melody.

But other synths had filters which could play an in-tune melody thataway.

Some synths you had a filter mod knob you would turn up to add keyboard cv. If the knob was all the way down, the filter didn't track keyboard at all, and then as you turn up the key cv mod knob, the filter tracks more and more. At some point in the knob travel, a third octave filter increase per octave of keyboard cv, then some higher point of knob travel you would get a half octave filter increase per octave of keyboard cv, etc.

So in that scheme it wasn't really negative key tracking. More like deciding how much positive keytracking to add. I would typically make patches that didn't have the filter keytrack knob turned up all the way, so that high notes didn't take off the top of yer head compared to low notes. Especially noticeable if the filter resonance might be turned up.

I think some synths may have had filter keytracking more hardwired than that, or maybe a switch just to turn keytrack on or off.

In some later hybrid or digital hardware synths, was the feature where 1:1 keyboard tracking was the default, and the synth gave you options to tilt the keyscaling either positive or negative slope, and optionally send a tilted keytracking control to several destinations, not just the filter. Which seems to me a reasonable workable way to use keyboard as modulator.

Probably doesn't answer your question. Just some info you maybe already knew.

[zerocrossing]

I don't think any of us knows what you're talking about. What hardware are you trying to match?

[Mutant]

Not asking about filter keytracking, but about note volume keytracking.
Set the filter to 100% open to take that variable out of the equation.

[Mutant]

I don't think any of us knows what you're talking about.

The higher the note, the lower the output volume of that note.
For example in Diva in Amplifier and Pan section set Keyfollow/Vol Mod -10

Seems to be THE solution to the common problem virtual synths have: bass notes are not powerful enough if compared to bass notes on real analogs.

(and it has nothing to do with the filter, i already said to fully open the filter, to just compare raw oscillator low and high notes)

[Mutant]

Now it seems kinda logical.
When designing an analog synth you would want all notes to be equally loud and human hearing is nonlinear and best in mid range, so boosting low notes (and high) would be a good idea.
I just wonder if they really do such thing in their analog circuits.

btw. I forgot to say that i am talking about poly synths.
Where you hit a chord with your right hand and hold 2 octave bass with your left hand and without that negative keytrack the bass notes would be barely hearable, totally overpowered by the chord.

[edit]
https://en.wikipedia.org/wiki/Equal-loudness_contour
This is what i am talking about.

[JCJR]

I don't think early synths had any built in vca modification to make high notes softer than low notes. Except in patchable synths, offhand I suspect many synths had no way of routing keyboard cv to the vca, but maybe that is just memory failure.

Most early synths had short keyboards anyway, couldn't hear a wide range of notes without transposing the keyboard or retuning the oscillators.

Am not trying to be argumentative. Most of the gadgets were real simple inside. Some patches were naturally loud, some patches naturally quiet. Would often adjust the volume on the synth or mixer, and tone controls on mixer, to get stuff the correct volume. Many patches would only sound good over limited note ranges.

I did most volume adjusting and envelope shaping with the filter. The vca only got modified after the filter was working in the ballpark. It is louder with the filter open vs the filter closed, except at high resonance levels. With no filter tracking and high resonance, whatever note range coincides with the filter tuning is the loudest range, and lower or higher notes are quieter.

As best I recall all the good vco's would generate close to the same peak to peak voltage regardless of pitch.

Edit: I see you were asking about poly synths. I think in general the above also applies to poly hybrids, except they had longer keyboards. Many of the poly hybrids had simpler voice structure than mono synths, because it was so expensive to add each programmable poly feature. They could only afford to add a certain number of poly features.

[Mutant]

Thats a good reply.
Thank you.

But still, i would like to hear that on analog poly synth A, note C1 gives RMS X and note C5 gives RMS Y.
Even if i am wrong and high notes are louder.
You can use the free Voxengo SPAN - it has many nice meter types, half of which i don't know what they even stand for... but at least i know that RMS is root mean square haha !

[JCJR]

Good luck maybe someone will help. I don't have any working analog hybrids to test or would do it. Was mostly getting tired of them back in the day and either sold em or they wore out.