Sign in to follow this  
Followers 0
bergytone

DOUT response to velocity

8 posts in this topic

Hello everyone

I'm just now working on midifying my old Zuckerman harpsichord with the midio128. So far, I have a working core and will be building up the DOUT modules soon. I have a couple of questions. Do I need to do anything with the DIN port; pull ups or pull downs on the serial data input?... or are they internally pulled high or low by the PIC?

Also, will the output of the DOUT change state on ANY velocity greater than 0? I have lots of midi files which play with variable velocities throughout, as most of you do too. So am I correct to say that note off = velocity 0 and note on = any velocity greater than zero?

This is a great forum, with great info and nice people, all creating some really awesome projects...I'm so glad I found it!

Eric

Share this post


Link to post
Share on other sites

Also, will the output of the DOUT change state on ANY velocity greater than 0? I have lots of midi files which play with variable velocities throughout, as most of you do too. So am I correct to say that note off = velocity 0 and note on = any velocity greater than zero?

welcome aboard!

DOUT = Digital out = High or Low = On or Off = nothing in between  :)

Share this post


Link to post
Share on other sites
[Also, will the output of the DOUT change state on ANY velocity greater than 0? I have lots of midi files which play with variable velocities throughout, as most of you do too. So am I correct to say that note off = velocity 0 and note on = any velocity greater than zero?

Yes, you are right.

And the DOUT will respond the same.

bassman

Share this post


Link to post
Share on other sites

you could use 2 doutmodules for one Velocity- one with a bigger and one with a smaller Resistor (and a standart diode in series- too prodect the circuit...)

Soo you have maybe:

Midivelocity 0: 0V (no sound) (Dout 1)

Midivelocity 0-100: 2,5V (normal) (Dout 1)

Midivelocity 101-127: 5V (Accentet) (Dout 2)

So you can accent 303ish with that. (if you dont want to use a aoutmodule for a  12bit resulution of velocity!)

its then "only" a software thing- but with this I cant help you.

Share this post


Link to post
Share on other sites

I always thought Harpsichord isn't a very dynamic instrument ...

Oh well.

Another approach would be to have a single DOUT pin for each note all held low at 0V by the PIC, going high to 5V to play the appropriate note. Then you have a single bank of (say) 8 DOUT pins on the other side of the circuit representing 8 different dynamic levels.  Using different resistors for each output of the final "dynamic" DOUT, you could effectively choose which resistor is used to complete the circuit to activate your string plucker.  You have created a matrix where one axis controls the note, and the other, the dynamics.

The problem with that method is that you couldn't have loud and quiet notes happening at the same instant.  All notes played at one time would have to be through the same "dynamic" DOUT pin.

Share this post


Link to post
Share on other sites

for velocity you have to take the "lute stop" it presses a "felt" (german: filz) to the strings and make it more "lopass", that is the "velocity" of the harpsichord"

When your harpsichord have a "lute" stop it will be a "global lute stop" and it is for all notes. (it is stick with felt on it...and it reduces the vibration)

But you could built your own "singel-note lute-stop".

So you have to "electro-mechanic" it...I dont know what is fast enough...for that, servo motors are too slow- for music.

When the harp-strings are off Iron (or magnetic), so you will need a electro-magnet- which, is sittung under the Strings,

over the magnet, you put a bit felt.

But I dont know what a electromagnet with DC make with your musik, but ok....that are only ideas.

For the Electromagnets...you could take a metric-winding-Screw---no Idea what diameter? it depends on the space between the strings....is big as possible I think...

then you you should rasp, the buttom of the screw plane. You take a Wooden or any other non-magnetic material, and drill holes for the Screws, after that, you take a nut, and screw the Screw in the holes, now wind a magnetic wire on the shaft that now look out of the Material

I never tried this in my live I dont have a harpsichord, but this is a idea, you have to make a prototype, and try, what magnetic wire, what screw diameter, how much Ampere and Voltage on the wire..... the distance between magnet and string...and so on.

;D

Share this post


Link to post
Share on other sites

Interesting!  I learned something today :)

So ... this "lute stop", is it normally operated with a pedal?  Do you use it with varying amounts of pressure, or is it strictly "on/off"?

If pressure is variable, you would most likely use a servo, similar to a motorfader.  You could probably even adapt MIDIbox MF module to control it.  Or, if you could find a solenoid that would work harder by varying its current, you could probably get by with only 4-8 dynamic levels, selected with a DOUT.  Each DOUT pin would be connected a different resistor (likely a trimpot), all of which would connected to the base of one FET, which could control pressure.  I think there is industrial automation equipment that does this type of stuff.

If it is simply on/off, you could control it with a single DOUT connected to a solenoid.

Share this post


Link to post
Share on other sites

Thanks for the  thoughts, everyone!

I think maybe some of you thought I'm trying  to get the DOUT module to respond to midi velocity. I was really just trying to verify that the MIDI128 code is written such that the output is active anytime the received MIDI velocity is anything other than zero. In other words, velocity = 0: output off, velocity = 1 to 127 = output on.

You are right.... the harpsichord doesn't really have dynamics, so it's very well suited to the midi128 design. I suppose I could somehow actuate the lute stop rail, but all it really does is slightly change the tonality of the notes. Not really a volume control, but a tone control.

I am now in the process of working out the electromagnet details, I will have to experiment to figure out the winding turns, wire size and the applied voltage. I'll keep you posted. I don't see anyone talking much about their experiences with solenoid design. Another website on an instrument called the 'Harpsitron' mentioned he used 200 feet of #30 to make his solenoids. The coil form appeared to be about 3/8" in diameter and about 1 1/4" long.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0