[dubble]

The different sound is nothing to do with the different kernel frequencies. The kernel frequency is the maximal frequency of the step signals and the OP has the same settings, same kernel freq. in Mach3 and the UCCNC and hears different sounds of the motors. Also different kernel frequencies will not cause different sounds if the running feeds are the same.

The reason for the different sounds is that Mach3 has a defective CV motion planner where the accelearions and deccelerations are often not optimal and especially the deccelerations are often higher than what you have setup in the configuration.
In the UCCNC the CV motion planner always obeys your settings and the profile is always perfectly symmetrical, this can be hear on the sound of the motors since the trajectories generated by the two system are different and therefor the sound.

An example logic analyser print of the X axis step signal with a simple G1 X0 ... X1 ... X2 movements

With Mach3:

Attachment 295098

With UCCNC:

Attachment 295100

Notice the different trajectories for the accel and deccel part in the Mach3 measurement, this has to be symmetrical if it was optimal.
With more complex paths the situation is often worse than this as this was a very simple one axis movement.

[mactec54]

The different sound is nothing to do with the different kernel frequencies. The kernel frequency is the maximal frequency of the step signals and the OP has the same settings, same kernel freq. in

Really, and the higher the step signals ( output Frequency ) the smoother the motors will run, with the motors running smoother, the sound they make also changes, this is not rocket science

[dubble]

Really, and the higher the step signals ( output Frequency ) the smoother the motors will run, with the motors running smoother, the sound they make also changes, this is not rocket science

Nope, the output frequency varies the running speed or feedrate in other words, has nothing to do with smoothness. The kernel frequency is the maximum output frequency.
There could be one thing which could vary the smoothness about kernel freq. is the max. jitter (maybe you thought about this), but there is no exact relation, so again the kernel freq. does not directly influence anything about motor running smoothness.
Moreover high kernel frequency like 4Mhz will make the system noise sensitive since 4Mhz frequency means 125 nanoseconds pulse width at 50% duty cycle, I would not run anything with this short pulses using step/dir interface, not even a hobby machine, but sure not a machine in an electrically noisy industrial environment.

[mactec54]

dubble

I understand what you are saying, so what is the reason for this to be happening, I know what you said in the first reply, that is normal for any good motion control, like I said that's not rocket science, we have known about Mach3 motion planner for 10 years, I would hope that your's is much improved

so if someone runs your UC100 with Mach 3 why do the motors sound better and run smoother, no other changes just adding the UC100

[dubble]

dubble

I understand what you are saying, so what is the reason for this to be happening, I know what you said in the first reply, that is normal for any good motion control, like I said that's not rocket science, we have known about Mach3 motion planner for 10 years, I would hope that your's is much improved

so if someone runs your UC100 with Mach 3 why do the motors sound better and run smoother, no other changes just adding the UC100

It runs smoother when adding the UC100 and still running Mach3 is because the jitter is in avarage 100 times lower with the UC100 than it is with the LPT port. Tens of microseconds range compared to hundred nanoseconds.
A stepper motor will run much smoother, because it runs in open loop and is a high pole count syncronous motor, so if the syncronisation is better timed, the jitter is lower means a smoother running.
Imagine a simple example of a fixed steps frequency running, e.g. 100Hz. The motor will run smoother when this 100Hz in realism is always between 99.9 and 100.1 and will run less smooth when it fluctates between 99 and 101. The same thing is what happens when you add the UC100 to Mach3, the signals will be better timed or in other words it will have less jitter.

[mactec54]

It runs smoother when adding the UC100 and still running Mach3 is because the jitter is in average 100 times lower with the UC100 than it is with the LPT port. Tens of microseconds range compared to hundred nanoseconds.
A stepper motor will run much smoother, because it runs in open loop and is a high pole count synchronous motor, so if the synchronization is better timed, the jitter is lower means a smoother running.
Imagine a simple example of a fixed steps frequency running, e.g. 100Hz. The motor will run smoother when this 100Hz in realism is always between 99.9 and 100.1 and will run less smooth when it fluctuates between 99 and 101. The same thing is what happens when you add the UC100 to Mach3, the signals will be better timed or in other words it will have less jitter.

This is the best reply yet, and is what It was meant to be in the very first post, this happens to anyone that has added UC100 or Smooth Stepper to there system, with the motors running smoother,this also changes the sound the motors make as well

As for the Smooth Stepper it defaults to 256 Hz and is adjustable down or up to it's max, so does not run at 4 Mhz unless someone was to try/set it at its max

[dubble]

This is the best reply yet, and is what It was meant to be in the very first post, this happens to anyone that has added UC100 or Smooth Stepper to there system, with the motors running smoother,this also changes the sound the motors make as well

Well, IMO this shoud not be the first post, because this is not an answer to the OP's question. This was an answer to your question only which was a different question than what the OP asked about.
He used Mach3 + UC100 and then he used the UCCNC + UC100 and comparing these 2 setups, therefor the jitter is the same and is not the answer to his question, the answer in this case is the different CV planner as I have described previously.