Loading speed & gain structure.....

Hello everyone,

I have owned an MPC4000 for about a year now. I have just started using it in a live performance.

In my experience so far it has been rock solid. Although I do have a couple of problems which I hope someone can help me with…

There are thousands of samples in my set. When I load from the hard drive the machine gets really slow towards the end of the loading process.
It is much faster loading from CD. Surely I have just missed the “defragment hard drive” function?

The other thing is the gain structure.

I like to use EXT1 – 8 set up in the mod matrix to fade various samples in and out.
What ends up happening is that the samples seem to play like midi velocity is being compressed.
Putting the samples in different zones and x-fading doesn’t seem to give the right effect.

Please could someone enlighten me on how the gain structure is laid out in the MPC?

Cheers

1881 wrote:Hello everyone,
Surely I have just missed the “defragment hard drive” function?

There is no defragment hard drive function.

You might be able to pull it out of the mpc, put it in a PC and do a defrag, but it's never
been tested by Akai, so I'd back up first..



Cheers,
Dave

you can defrag the ram only

Thanks for the comments,

I think I will stick to loading from CD rather than risk messing up the HD

That is interesting on the CD being faster. Have you tried from ak.sys or a USB device and gotten similar results?

Unfortunately I do not think you are going to find a solid explanation on the gain structure as I have never seen one, and without knowing the code, we can only guess. Unfortunately the extreme flexibility often makes tasks much more complex than they should. Since there like 10 points where amp/pitch/filter/etc can be changed (and a hundred more through modulations), there really isn't a formula. Just keep in mind that a setting change from one area can throw off what you did in another.

I've noticed in quite a few applications the same problem you have. I'm not sure if the problem is with the audio gain/mixing or the modulation curves. I put together a virtual synth patch that changes waveforms, but to be honest, you really can't expect it to merge the waveform, it is mixing 2 waves together. Aside from that, the fades can be tricky too. Usually a log curve helps and some play with the overlap. Having more iterations can help smooth this, but it is a lot more work.

Simarly, I've tried several times to make a surround panner with a midi joystick and the mod matrix, but the manual pans never quite come out the same as the built in stereo pan. Maybe the curves aren't the same. Although not perfect, there are a lot cool things that can be done. On my last experiment I figured out how to use the LFOs to apply a surround swirl to a sample/keygroup.

Hi McSmooth,

Thanks for your comments.

When I was building the project and loading from aksys, the load time was much faster.
I can live with the loading time from CD, so not too much of a problem in reality.

I am thinking of trying to use MIDI expression messages to see if that gives the effect I am after.

Other than that - like all hardware - I guess you just have to try to convert 'problems' into useful features of the machine and get on with the job.

Akai NEVER documented the gain structure,
and I was asking them about it from, um, August 2002,
like every month for 4 years,
and never got an answer.

Basically though there seems to be only TWO gain stages,
One is the GLOBAL mode pad (which comes before the final DAC - so if you are getting clipping, turn down the global mode volume - I usually have mine at -12dB).

The other gain stage is affected by EVERY other parameter -
part level, program level, keygroup level, zone level, filter attenuation, sample amplitude, the Mod matrix, MIDI cc 7, the LOG/LIN switch in your program, and probably some others I forget.
They ALL affect it, and as you noticed, you'll soon hit a "ceiling" in level and not be able to get any louder......

If you turn several of those parameters down by a fair whack, you'll start see volume change linearly with MIDI velocity 1 to 127.....