Just how bad Is the volume issue

Hi guys this is my first post on the forum so apologies if this has already been covered somewhere

I have recently been looking into getting an MPC500 as they look like great little units, however I've heard a lot of people saying that the output from them is pretty quiet in comparison to the other MPC's. Exactly how bad is the volume issue, would the 500 be loud enough to just make simple beats and record the raw output through a mixer and onto a computer, without processing or is it way too quiet. Also what is the general sound quality like in comparison to other samplers such as the sp404

Many thanks guys

No it's fine. I had one in last week and I did notice it was a little when using headphones, but even this is ok because there is an output volume boost setting in a submenu. I think its in pad 8/ "other" mode.

It really is fine. The headphones output is really quite if you use real headphones, but that depends on the ohm's of the headphones.If they are difficult to drive yes it is going to be a problem. The stereo outs though haven't been a problem for me, especially when using it via a sound card or any kind of preamp obviously. There is also this setting where you can adjust the headroom of the mpc, but this really depends on the polyphony used. If you use lots of samples, then you'll have to readjust the headroom so that your mpc does not distort. Actually my emu's 6400 is not much louder than my little mighty mpc, I would say 5-7% pick level more.

When people say its quiet, they mean you get no white noise or hiss from the inputs and thats great for sampling.

Its a loud talkin' sonuvabitch imo.

Mine has quite loud noise on both inputs and outputs, I guess this could be remedied by performing a decoupling mod.
Does anyone know about any guides out there?

DjDiskmachine wrote:Mine has quite loud noise on both inputs and outputs, I guess this could be remedied by performing a decoupling mod.
Does anyone know about any guides out there?

First of all I must admit that my 500's inputs and outputs are not noisy . At least not more than my miniak or evolver.
A decoupling mod is something I hadn't thought about. You can check the service manual for the schematics, I did check it some months ago and it seems that there is sufficient decoupling almost everywhere.
The mpc has 3 of the same psu ic's to supply three different voltages if I'm not wrong. So you should start by decoupling those, but this is probably nearly not enough, you should decouple every ic and more .
I guess if the power section ic's are already decoupled as suspected then the difference would be negligible and completely inaudible .I did mod the midi output of the 500 so it can power external midi devices (like the quicco mi.1) and after I tried to change two resistors to make it up to par with today's midi standards but these were surface mounted and not serviceable by me. So that could be an extra problem for you too.

Anyway, if you really are wanting to try this, here is the info you gonna need .
http://www.ti.com/lit/an/slyt199/slyt199.pdf
http://www.analog.com/media/en/training ... MT-101.pdf

And of course as much help as you need by me

quoting the second pdf, Decoupling is :

"A large electrolytic capacitor (typically 10 μF – 100 μF) no more than 2 in.
away from the chip.
The purpose of this capacitor is to be a reservoir of charge to supply
the instantaneous charge requirements of the circuits locally so the
charge need not come through the inductance of the power trace.

A smaller cap (typ. 0.01 μF – 0.1 μF) as physically close to the power pins
of the chip as is possible.
The purpose of this capacitor is to short the high frequency noise
away from the chip."

Still away: thx for the input. Dont have another hw sampler so I dont have any comparison, but the 500 is defo one of my noisiest pieces of equipment!
Maybe I'll start out by checking the decoupling caps that are already in there, I'll start out by checking by oscilloscope close to the power section(s) and try to figure out what's the cause of the problem.
Might be as easy as a bad cap in there, seems suspicious since u say that your unit is not noisy.

Thanks for your support, I'll report back with my findings & results. :3

MPC500 noise elimination trials

I suspected the caps that are associated with decoupling the output voltage from the power regulators to be the culprits - I was correct to some extent.

The C911 seems to be the cause of a lot of pinkish noise on the headphone amp - this is the rail that produces +3.3V from the main power
Decoupling the main input seems to have no particular effect.
There might be some improvement by swapping the caps, but I cannot be certain until I can swap them with some proper caps of the same capacitance

C912 Does have some minor effect on the audio quality..

C910-C912 have the value 220uF


It can’t be ruled out that the caps on the inputs from Mainpow have a similar influence on the audio quality, but it’s a lot harder to experiment with them due to their tiny size.

These have the numbers C901-C903 and have the value 47nF.
These work in conjunction with C907-C909 with the value 100uF

The changes in the tone from the output of the headphone amp was approximated by using a 22uF cap that was applied in parallel over each cap mentioned above.

I’ve made the conclusion that the caps are starting to get bad, all are by the brand Lelon which seem to be notorious for failing.
I will attempt re-capping a few of them and see if I’m satisfied with the amount of noise reduction.

Hope this helps, but I use gold cables. Not sure it'll help improve sound but cheap cables give a cheap sound.

DjDiskmachine wrote:Still away: thx for the input. Dont have another hw sampler so I dont have any comparison, but the 500 is defo one of my noisiest pieces of equipment!
Maybe I'll start out by checking the decoupling caps that are already in there, I'll start out by checking by oscilloscope close to the power section(s) and try to figure out what's the cause of the problem.
Might be as easy as a bad cap in there, seems suspicious since u say that your unit is not noisy.

Thanks for your support, I'll report back with my findings & results. :3

Hey DjDiskmachine,

Sorry for taking so long to answer. Now that I saw the thread I will fire up my oscilloscope in the next days to see what is actually happening. Tell me if you need an image of the output to compare.

Now for the noise elimination, I'm no pro to this but this is what I would do.
First to find out where the noise comes from, compare headphone out vs Line outs. Having in hand the schematics you can understand that if the noise is the same you'll have to look before tlc084c. Probably first check would be c38 and c19. If noise is different you should check after tlc084c, c301-304,c401-404. Checking those would help eliminate noises introduced by faulty caps and insufficient filtering. I saw you checked for noise introduced from the psu's .Now this seems highly likely but you checked the decoupling caps I think, c901-903 c907-909 seem much more likely to affect the quality of sound. But before all these I would suggest tapping in all those places with your oscilloscope. This would most likely reveal the noise and where it comes from so you know where to focus on.

Daydreaming
recapping the whole mpc plus changing some trannies and even the tlc's would probably change the audio quality quite alot . Although dealing with all those tiny smd's would be really annoying .

Ask me for help.

Hey still, no worries. I've been having the MPC disassembled for a while now, while debugging it step by step.
I was pretty satisfied with audio probing it and ended up only replacing the electrolyte caps that are there for decoupling the power rails.
I figured that the source of the noise was probably due to power-rail fluctuations and managed to get rid of almost all of it, except for an ever so quiet constant tone, but this is so low it's almost inaudible.

The caps I replaced were C907-912. Checked the decoupling caps C14,18,46 on the OP amps but it didn't seem to do much of a difference. 401-402 and pretty much all of those in the end of the audio rail didn't seem to do that much either so I just left them where they were. C175 decouples the power rail to the LED backlight but that didn't seem to have much of an effect either.
C38 & C19 are performing DC blocking from IC19 on the output so I pretty much ruled them out since they aren't performing any high-frequency filtering.

The caps I ended up getting were of the brand Nichicon, a friend of mine who does a lot of Amiga re-capping could vouch for them.

Ill Green: Yeah, but u better make sure it's solid gold cables, not just gold plated copper since electrons run faster in gold as you know.
This is why I got Gold Capacitors.
https://www.instagram.com/p/BZCS0jpH9cw ... iskmachine

I got in touch with Akai pro, they said they'd never heard of this problem and told me to get in touch with a licensed MPC repair shop without hinting how one would go about finding one.
A friend of mine owned two of these units up until recently and he said he'd defo heard some kind of whine/noise sound when using his so..
As I put the unit together, I decided to treat me to some red fat pads from MPCstuff. The unit looks friggen dope and makes it so much more playable, totally worth it compared to the mod I did with rubber from a bike tube ;D

If this problem should happen to someone else, I hope they can find some of this stuff useful.
Thanks for all the support and baring with my ramblings ;D
Cheers!