15 Dec
2021
15 Dec
'21
12:02 a.m.
Dear list,
I'm mainly using Pianoteq and setBfree for live performance. To quickly adapt my
sound volume of both SoftSynths together I'm using a foot pedal to send Midi
volume commands to both applications. Unfortunately that is not working very
well for both programs are using the Midi volume values (0-127) differently.
Pianoteq adjusts its output volume according to a more logarithmic manner while
setBfree seems to handle it linearly. Thus if I adjust both volumes to a similar
SPL for Midi value = 127 the organ is way to loud at lower levels compared to
Pianoteq.
Meanwhile I have found the location in the source of setBfree where I could make
adjustments. I have measured the logarithmic dependency of Pianotec's Midi to
volume characteristic and found a formula to be used in setBfree to get a
similar performance. It would be nice if this could find its way into the
original source.
Now I have the following questions:
Does anyone of you know if the original swell pedal of the B3 is changing the
volume in a linear or logarithmic way? Maybe if the original B3 uses a linear
characteristic we should not change setBfree's code.
The function I'm using is mimicking Pianotec's characteristic. Maybe there is a
more global approach for changing from linear to logarithmic behavior over Midi
volume values? Surely for me it's ideal when both Synths have same characteristic.
Do you know a source where I can find more general info about lin<=> log
conversion of Midi volume in software? How is it handled in other professional
programs? I know that every amplifier uses a logarithmic pot for volume control
to follow more the human loudness perception.
Do you think its worth the effort to send a patch to github's repository (I've
never done such a thing so far)?
Thank you for your time
Gerhard
15 Dec
15 Dec
12:13 a.m.
On Tue, Dec 14, 2021 at 11:02:27PM +0100, Gerhard Zintel wrote:
Does anyone of you know if the original swell pedal of
the B3 is changing the
volume in a linear or logarithmic way? Maybe if the original B3 uses a linear
characteristic we should not change setBfree's code.
It's very probably neither lin nor log, but whatever the hardware
(i.e. the potentiometer in the pedal) provided. Maybe tuned a bit
using one or two fixed resistors) to 'feel right'.
--
FA
2:01 a.m.
Gerhard Zintel <gerhard.zintel(a)web.de> writes:
Does anyone of you know if the original swell pedal of
the B3 is
changing the volume in a linear or logarithmic way?
Here's a quick recording from the output of my C3 (same internals as the
B3 in a different case), with the drawbars at 88 8888 888, holding down
Cs across four octaves and moving the swell pedal as smoothly as I can
between the endstops:
http://offog.org/stuff/c3-swell.flac
This looks more or less linear to me by eye. Note it doesn't go all the
way down to silence.
However, in terms of the preamp circuit it's not quite that simple --
the swell pedal isn't a variable resistor, it's an unusual variable
capacitor with two fixed plates and a moving one, in between two valve
buffer stages. One fixed plate is fed directly from the previous buffer,
and the other is fed through a filter circuit -- so effectively the
pedal is crossfading between the full signal and a filtered and
attenuated version of it (simulating a real organ's swell box with the
shutters closed, I guess), which means that there's some variation in
the frequency response as well.
This also disregards any nonlinearity in what you're playing the organ
into -- if you're doing the traditional overdriven Leslie thing, then
there'll come a point where it gets crunchier rather than louder...
Cheers,
--
Adam Sampson <ats(a)offog.org> <http://offog.org/>
3:07 a.m.
On 12/14/21 11:02 PM, Gerhard Zintel wrote:
Now I have the following questions:
Does anyone of you know if the original swell pedal of the B3 is
changing the volume in a linear or logarithmic way?
Neither, and it is complicated.
Since the gain is applied before the pre-amp, many refurbished B3s use a
lamp and photo-cell/resistor to reduce hum, so any mapping is possible
there. But as far as I know, the original B3 uses a variable capacity to
control volume, which is linearly interpolating between 2 levels.
The pedal is connected mechanically via a rod, which connects to an arm
in the expression control. This adds some ratio. So while the electrical
control is linear, the overall throw is not.
Also as opposed to setBfree, many B3 pedals do not allow to go fully
silent, either.
Maybe if the original B3 uses a linear characteristic
we should not
change setBfree's code.
There is also the problem that this would change
existing projects that
use setBfree as plugin. Changing the expression pedal mapping will make
those sound different, so this is not an option.
--
robin
10:31 a.m.
On Wed, 15 Dec 2021 02:06:19 +0100
Robin Gareus <robin(a)gareus.org> wrote:
On 12/14/21 11:02 PM, Gerhard Zintel wrote:
<snip>
Exactly! That was very common with a lot of 'portable' electronic organs of
the 1960s too, and a bit of a nightmare. There was quite a wide range in
photocell responses, along with changing output from the bulb depending on age
and supply stability.
--
Will J Godfrey
https://willgodfrey.bandcamp.com/
http://yoshimi.github.io
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.
Now I have the following questions:
Does anyone of you know if the original swell pedal of the B3 is
changing the volume in a linear or logarithmic way?
Neither, and it is complicated.
Since the gain is applied before the pre-amp, many refurbished B3s use a
lamp and photo-cell/resistor to reduce hum, so any mapping is possible
there.
9:49 p.m.
Hi, you guys,
On 15/12/2021 02:06, Robin Gareus wrote:
thanks a lot for your insight and comments (especially Adam for your time to
make measurements). After this short discussion I realize, that my approach to
control several softsynths by only one volume sweller sending Midi controller
message 7 to them individually seems not to be a good way to do it.
Obviously its far better to use a jackable master volume control device in front
of system playback (within QjackCtl) that is able to receive Midi controller
messages. I hope jackmix will do the job - I'm on my way to set it up. It seems
to be the program with the lowest footprint. If you have any other idea what to
use for the purpose please tell me.
Thanks again
Gerhard
Maybe if the
original B3 uses a linear characteristic we should not
change setBfree's code.
There is also the problem that this would change
existing projects that
use setBfree as plugin. Changing the expression pedal mapping will make
those sound different, so this is not an option. 
16 Dec
16 Dec
10:18 a.m.
I happen to use Pianoteq as well as setBfree for live sessions.
I use Carla as host and with Carla I can put midi filters before the
instruments and I am pretty sure there are filters that can be used to
mimic the behavior you are looking for.
Regards Anders
On Wed, Dec 15, 2021, 20:50 Gerhard Zintel <gerhard.zintel(a)web.de> wrote:
Hi, you guys,
On 15/12/2021 02:06, Robin Gareus wrote:
thanks a lot for your insight and comments (especially Adam for your time
to
make measurements). After this short discussion I realize, that my
approach to
control several softsynths by only one volume sweller sending Midi
controller
message 7 to them individually seems not to be a good way to do it.
Obviously its far better to use a jackable master volume control device in
front
of system playback (within QjackCtl) that is able to receive Midi
controller
messages. I hope jackmix will do the job - I'm on my way to set it up. It
seems
to be the program with the lowest footprint. If you have any other idea
what to
use for the purpose please tell me.
Thanks again
Gerhard
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Maybe if
the original B3 uses a linear characteristic we should not
change setBfree's code.
There is also the problem that this would change
existing projects that
use setBfree as plugin. Changing the expression pedal mapping will make
those sound different, so this is not an option.
1005
days inactive
1007
days old
linux-audio-user@lists.linuxaudio.org
6 comments
6 participants
participants (6)
-
Adam Sampson -
Anders Hellquist -
Fons Adriaensen -
Gerhard Zintel -
Robin Gareus -
Will Godfrey