MPC frequency tests

 

How the test works

This is designed to be a simple test so we can see what happens when we record a swept sine wave out of various Akai MPC machines. We can gain a better understanding of the different sonic characteristics of these machines doing this, as a separate issue from any subjective ideas of how the machines 'sound'.

This is the simple process:

a) Load in the 2kh - 22khz swept tone into the sampler. On some earlier samplers, it may be difficult to do this without physically recording the sample into the machine. Just note that this is the way it was done. On newer machine, it should be easy to load in the pure .wav sample.

b) Play back the sample from the machine (remember to remove any effects, EQ, filters etc)

c) Record the tone back into your system, save it, and send it to me!

d) As a final test, you can play the test tone straight back in thru your system to give us a rough idea of what your system sounds like by itself. Use Cubase or another multitrack sequencer for this, simply place the test tone on a track, play it back thru an output of your computer / mixer / soundcard, connect a cable back from the output to the input, and record the input. Be carefully you don't set up a feedback loop doing this. Send this to me, along with all info about the methods and equipment used.

 

MPC 4000 output

This is what started me off on this test - some unsubstantiated claims on the internet that the MPC 4000 'rolled off the bass below 120 Hz'. Since I just got a 4000, and it sounded good to me, I wanted to know for sure what was happening. As you can see from the image below of the swept tone from 2hz on the left to 22Khz on the right, it is basically flat, with a tiny hf roll of, about 0.1 db, from around 7hz up until the 20Khz cut off point (you can see this at the end where the sample dips to a point then rises again). The sampler managed to reproduce the 2hz tone no problem, the small rise in the frequency response on the very low end may be due to my mixing desk offset compensation (see below).

AKAI MPC 4000 OUTPUT FREQUENCY RESPONSE
The MPC output is at the top, the flat tone is at the bottom.

 

MPC 4000 Input

As requested, here is the MPC 4000 input (record in) frequency response. The waveforms are lower in amplitude because there is a DC ofset at the start of the MPC file, I think this is due to some automatic DC ofset compensation on the MPC. Remember this test starts at 2hz, which is almost DC anyway. The lowest note we can hear is around 20hz. Further up the waveform, there is a tiny bulge at around 9Khz, then a droop to 20khz with a deep cutoff that starts a bit lower than the output conversion waveform. This waveform overall doesn't look as good as the output waveform, sugesting that anything sampled into the MPC 4000 using it's own converters may have slight high frequency losses, and that using a different converter will lead to subtley different results.

AKAI MPC 4000 INPUT (Record) FREQUENCY RESPONSE
The MPC is at the top, the flat tone is at the bottom.

 

Yamaha 01V96

This is the 'control' test, where I put the signal out of my desk (a Yamaha 01V96) and recorded it coming directly back in. As you can see, the Yamaha's frequency response is very flat, with a small bump in the very low end of about 0.2dB, probably due to DC offset compensation kicking in on the 2hz tone.

YAMAHA 01V96 OUT TO IN FREQUENCY RESPONSE
The 01V96 test is at the top, the flat tone is at the bottom.

 

MORE TESTS NEEDED!

I am especialy interested in the MPC 1000, MPC 3000, and MPC 60 tests, but the MPC 2500, MPC 2000, and MPC 2000XL would be great as well. I will also accept any other tests anyone wants to do any any other aspect of their system, especialy other samplers and other mixing desks. Just download the test swept tone, and follow the instructions above, then email me the results! It should take you about 5 minutes.

 

 

 

 

© AudioPervert  21st Sep 2008