Exchange tips and tricks for the Akai MPC4000
By shoestarr Fri Jan 29, 2021 10:00 am
Hi,
I have some strange problem when recording samples through "Analog In" in to my MPC.
Most of the time I get a clean and perfect result when recording. But now and then, with the same recording input levels (of source and mpc) there is a lot of annoying hissing noise mixed in it.
Thinking it might have something to do with RAM, I tried different Bitrates and Recording-time-Settings.
And indeed the noise disappeared almost all the times when recorded with 16Bit.
But the strange thing is that the noise is not occuring when recording in 24bit and a timelength of ca. 20min., but it is appearing all the time when recording in 24bit and a timelength of <2 min.
I also tried it in different settings (meaning different soundsources, small projects, larger projects.)

Has anybody experienced something similar or has it been already discussed? I was looking through the forum but couldn´t find anything exactly matching this issue. So as it is not essentially breaking the functionality of my MPC, it still is very annoying and worrying though.

If anybody has an idea where to look and how to fix it, I´d be super thankful!
cheers!
s

PS:Sorry for my bad language and long writing
User avatar
By dabmeister Fri Jan 29, 2021 12:00 pm
Just gathering some info to help solve your problem. So what are you using to monitor your sound?
User avatar
By Sense-A Sat Jan 30, 2021 9:45 pm
You sure it isn't the SOURCE of the analog in causing the problem?

It might not be the MPC at all. It could be hissing or a ground loop problem or something associated with the source of your sound.

This could be especially true if you are recording from a turntable or have a phono signal somewhere in the analog audio in chain.
By shoestarr Mon Feb 01, 2021 8:53 pm
Sense-A wrote:You sure it isn't the SOURCE of the analog in causing the problem?

It might not be the MPC at all. It could be hissing or a ground loop problem or something associated with the source of your sound.

This could be especially true if you are recording from a turntable or have a phono signal somewhere in the analog audio in chain.



Hi Sense-A-

thank you for getting on this. I experienced this on different setups. One time sampling my Dave Smith Evolver, the other time my Moog another time sampling from the computer.
That being said, I also have to add that it doesn´t occur all the time. There were occasions, while troubleshooting this problem, when it didn´t occur (i.e. when turning the mpc on -> setting the output channel -> record mode on (default: 24bit, 10 sec) and sampling. Then after a while of messing around, programming, jamming, whatever … then, however, when I was having a couple tracks w/ different programs going and I wanted to add some more it would start to do the hissing again :-(
I usually work with about 10 Parts / Programs / Tracks, meaning each track with a different part etc. … Some Tracks are routed to my Synth, some are using the samplebased Programs … I don´t use too many of the internal effects, so the usage of RAM is fairly low, no?
My first guess was/is, that old RAM-Sticks are causing the problem. I think this, because I have the feeling that only after a couple hours of messing with the 4k this hissing problem starts … 

Don´t know. I mean, in the end of the day my 4k is not broken and still highly usable, so it´s not a big drama. But it is just something that came up recently, which is worrying a bit. So I thought I´d post it to see if anybody had similar experiences with the 4000. Any suggestions are very welcome and appreciated though!

s

ps. excuse my language and typos: I am not a native speaker :popcorn:
User avatar
By Sense-A Mon Feb 01, 2021 10:24 pm
I doubt it is the ram. Replacing the ram is cheap (Under $20), but I don't think that is the cause of the problem.

I still think it is a grounding problem, a fan, a spinning hard drive, or the inverter behind the LCD. Any spinning parts can add noise/humming in an audio path. Grounding problems can cause hissing/noise. Inverters have a small transformer that can insert high pitch noise (common problem in old Akai S1000's and S1100's).

1. Make sure all components in the audio chain are plugged into the same power conditioner and share a ground.

2. Disconnect the internal fan and internal hard drive and CD ROM and see if the problem goes away. A spinning CD ROM or Hard drive or fan while you are recording could introduce a high pitching noise in the pathway.

3. Check the amplifier you're running your output signal into.

4. Look at the circuit board around where your audio inputs are. Do any capacitors appear bloating or swollen? And residue or dust?

5. Make sure your audio cables are not running parallel to power cables. Try to keep audio cables away from power cables.

6. How intermittent is it? Does it hiss the entire recording? Does the hiss fade in and out during a single sample? Does it occur regardless of which outputs you're using? What if you use SPDIF output instead of analog output? Still hear it?