Keyboardpartner-Forum

Hi
The clock of FPGA has nothing to do with tuning.
FPGA clock is a system clock and all things inside a FPGA run in parallel there is no pipeline of any routines like in normal processors.
That´s the great difference !
A programmed FPGA works like pure hardware. The program only tolds the FPGA where and how any connection had to be realized.
When the programm ends You have a "hardware with wanted functions" just like soldered chips
FPGA means Field Programmed Gate Array

So the correct definition is not to program a FPGA but configure a FPGA

I am dealing with translations of the German to English so it may not be correct but previously in this thread Carsten appears to have posted the following

"the physical model assumes a fixed frequency"

"The FPGA clock is currently at 70 MHz"

I am assuming that the physical model is using the 70 MHz clock as it's frequency basis for the generation of the 91 tonewheels.

It seemed from the earlier posts that if the clock frequency is changed then the 91 tonewheel frequencies will change as well since they appeared to be generated based on the master clock.

hi
You must read Carstens indications correctly .
Inside the FPGA is a Hammond Generator implemented which only supports 91 virtual Tonewheels.
There is NO WAVE OR SAMPLE in it which is able to be tuned
If You transpose or octave shift the KEYS they also use the same 91 virtual Wheels. No frequency above 6000 Hz is generated
exact like in Hammond.
So if you move virtually the Keys on octave higher You will miss these octave on lower side, same when You move downwards You wil miss
then on upper side.
Exactly this has Carsten told.
So it´s impossible to use two Hoax with any octave shift or transpose in parallel mode.
If You use two Hoax parallel with different MIDI Chanels the Frequencies wil repeat after 5 octaves.

If You use a Clone based on Waves or samples it is possible to shift like You want, but the HX3 isn´t based on that it´s physical modeling

88 notes = 7 octaves + 4 notes ~= 7 1/2 octaves

Each HX3 covers 61 notes = 5 octaves +1 so 2 boards, in theory could cover 10+ octaves if the note ranges could be fixed as I asked

If the first HX3 was set an octave higher then I could feed the upper 44 notes of each keyboard to that unit and feed the lower 44 notes to the second unit that was set for two octaves lower.


This could be done using physical wiring or, since a HX3 board can be configured for the default channels of 1,2,3 or can be changed to a different set of channels,
in a pure midi environment I could do a keyboard split on each keyboard so that the upper 44 would be on one channel and the lower 44 on a different channel. If I merge the keyboards and then split the mid signal and feed both boards then each board would only respond to the notes on its channels.

Technically this is quite easy to do, the real question is whether the design of the HX3 allows for a clock change that only affects the tone wheel frequency generation without impacting other parts of the modeling.

In a prior post Carsten indicated that it was not possible to do dynamic frequency adjusting such as user adjusting A between 440 and 444 Hz but left open the possibility that a fixed frequency change might be possible.

Over and above the clean integration with a midi setup using 88's, it would be fun to have a B3 generate the 32' and 64' ranks only found on large pipe organs. I have equalized subs that are flat to 20HZ and only 3 db down at 10 hz so I can handle a 64' C without a problem. (not so sure about the room though !)

Jimbo hat geschrieben:Is it possible to set the HX3 to an octave higher or two octaves lower ? Thinking of using 2 boards to use 88 key keyboards.

That won´t run NEVER EVER

The HX 3 anyway which variation ( expander via MIDI or buildt in connected direct to keys ) only accepts in each manual 61 keys - nothing else.

In case ( if it can made ) of transpose plus one octave higher You will miss the lower octave !
Same when transpose two octaves lower You miss the two octaves above on higher side.
The full range of 5 octave manuals You ONLY have when on CENTER POSITION like original Hammond

you may split your 88 and take OM on the Right, channel 1, UM on the left, channel 2

Is it possible to set the HX3 to an octave higher or two octaves lower ? Thinking of using 2 boards to use 88 key keyboards.

Ich werde aber trotzdem mal mit programmierbaren Taktgeneratoren wie dem DS1077 von Dallas experimentieren. Der DS1077 geht je nach Ausführung bis 100 MHz. Beim FPGA-Takt ist derzeit bei 70 MHz Schluss, sagt die Synthese -- aber weniger geht immer. Fraglich allerdings, wie die FPGA-internen DLLs (Delay Locked Loops) auf dynamische Taktänderung reagieren...

Danke für die Antwort.

Äh... Nein, das physikalische Modell geht von einer festen Netzfrequenz aus. Es besteht im Prinzip die Möglichkeit, die Zahnradübersetzungen zu ändern, das wäre aber eine eigenständige Konfiguration. Wollte ich mal für eine Art H100-Zusatz machen, mit zusätzlichen Fußlagen in leichter Schwebung, so wie bei einer BC.

Stufenlose Änderungen kann die PLL im FPGA leider nicht. Bliebe die Möglichkeit, den 50-MHz-Takt variabel zu machen. Das ist ziemlich Hardcore.