Unexpected noise from AKAI and Yamaha

[MikeMiller]

Hi friends! Tried to figure it out in another forum but it seems like nobody knows the answer there.

I've bought an AKAI s1100 and Yamaha TX802. The units are in great operation condition, everything works, but.....

There's one little thing that doesn't allow to use them at all. It's a hiss or a white noise on both units and a high-frequency hum on the AKAI. What's wrong can be with that gear? Is it age or what? Since everything's working and loading why the output is so noisy?

I've bought them to avoid software emulations (FM7 and software samplers) to get the right sound but it seems like with that hiss "sofware guys" will only laugh at my "hardware perfection" =( *very upset* I wanted them so much and now I feel like i've been fooled by myself.

If more details or sound samples needed to define the problem I can provide it!

Thanks!

[._.]

Could it be a ground loop? Google it.

[MikeMiller]

Does ground loop provide a white noise? OK, i'll try to google it. I doubt it's a groundloop since Yamaha TX802 for instance has no ground (a 2-pin power cord).

Moreover, my MOTU 828 Mk3 doesn't make any hiss or noise though it is connected to the same socket.

[MikeMiller]

Guys! Some important update! I plugged headphohes to a "phono" jack and no hiss, no noise, no hum! A clear sound. It means that the chips are ok! But when I connect smth to an output it becomes hissing and noising.

[Muser]

electrolytic capacitors could have failed on the power board.

sometimes a midi cable having the center earth pin connected can do it.

sometimes a ground loop can too.

if you make a mains cable with (just) an earth wire connected to the plug is useful to test how earthing the metal shell on a unit to ground, it can be useful to test for (lack) of ground.

if it starts when you plug a midi cable in, it could help to have a cable with no center pin ground.

obviously if its a break down in any circuitry, it's a different level of difficulty

eliminating audio cables as the cause 1st, is also worth doing..

[MikeMiller]

Muser, you mean the powerboard which is responsible for powering the unit? (connected with AC plug and on/off switch). Well, looks like it is time to bring it to a service center.

In my mind a midi cable can't be the reason of noise. But I'll try to check it right now and unplug it. Also since I'm outside the US i'm using a 220/110 switch and it has no ground at all. Besides, my house is not actually grounded.

One more important thing is that when heating AKAI starts making a constant beep noise coming from the box. I don't know what it may be. But what's interesting is that a "phono" jack is the only one which works as it should when plugging headphones! It's very strange...

[LeeYoo]

What do you mean with "I'm outside the US i'm using a 220/110 switch"..

[MikeMiller]

It means that I'm living in a country where we have 220V AC and I have to use an adapter from 220 to 110V.

Yesterday evening I finally defined what is making noise and what isn't.

1) AKAI doesn't actually make much hiss but it makes a 60Hz hum.
2) Yamaha makes hiss but that's probably a capacitors issue.
3) MOTU 828 mk3 (new) makes the main hiss. First, rear analog inputs are very low so when I plug AKAI i.e. to then analog input 1 I have to trim it in cue mix up to +20 and more. Otherwise the input signal is very low while recording. I found it when I ocasionally unplugged the cable from MOTU and it still was making hiss!
4) 1-2 front MIC inputs are also making hiss when trimming them more than +10!

Today I'm going to test my ex-interface (X-Fi elite Pro) and MOTU to compare signal to noise ratio. I can't remember if i ever experienced noise issues with audio interface. Only with external units or guitars....

So the main trouble as it revealed is probably with my new MOTU. I thought it is a high quality recording interface which doesn't need additional preamps for recording sampler or synth units. And why making preamps that start making noise when trimming them more than +10?)) It means that actually any value more than +10 is useless in recording though the max value is about +50 or more (incredible hiss).

[LeeYoo]

I already understood that you are using 110v gear on 220/230volt power.
What I should have asked is if you are using a proper stepdown transformer with at least the total power rating of the gear.
Not some cheap triac based reducer for resistive loads. The word "switch" was not clear.
I see you have problems with most of your gear, so power is the first thing to check.
Leo..

[MikeMiller]

yes, stepdown transformer supports up to 70W units and AKAI is only 50W. But it is only 2-pin (it has no ground pin) though AKAI is supplied with 3-pin cable (with a ground pin).

Suppose that the power may cause mains hum problem. But the white (digital) noise is still up to MOTU. In the manual they said that I can plug directly samplers and etc. in the rear analog inputs. But in fact if I don't use a preamp the input signal of those jacks is very low! Is it something wrong with my inputs or is it just a MOTU feature? I'll say it again: to get a relatively loud signal from the rear input I have to trim it in cue mix to the max value and the signal is still not loud enough. I logically turn the volume knob on AKAI at max to reach an appropriate record level and again get the white noise.

[MikeMiller]

Is DI box a possible solution?

[Muser]

Muser, you mean the powerboard which is responsible for powering the unit? (connected with AC plug and on/off switch). Well, looks like it is time to bring it to a service center.

no I meant the power board in the Akai or yamaha.
eventually the electrolytic capacitors break down.

but, 60 Hz hum could easily be some kind of ground loop.

try either connecting the earth on Akai power cable or lifting it.
the opposite of what it is currently.

sometimes the earth in midi cables can indeed create ground loops.
not often, but sometimes.

Those Motus don't seem to run a ground anyhow do they these days. ?

some meter or cable tester with an audible continuity tester feature are pretty important for these kinds of issues. you want to know which units are getting to earth / ground and which aren't. you can often establish that by touching the metal shell of a jack thats plugged into a unit and then touching the chassis of the unit. if the chassis also connects to the earth pin on the power plug you know that the main power ground is traveling through the sleeve of the jack plug. (you don't need it connected to power to check that)

then you see if the jack plug does the same on other units too. you slowly build a picture about where earth is going and where it isn't going. getting all that right can remove a lot of crap from your signal. and that might have nothing to do with capacitors.

so a power cable or small power extension (without) an earth can be
really handy as a quick diagnostic tool.

the ground on an audio cable often carries the main ground.
not always but often. so if you have two bits of kit, both with ground and
the audio cable carries that to the other unit, they both try to find ground
and the potential difference between them both trying to find ground is often what causes an earth loop hum.

you don't want to change caps if you don't need to.

also, as the Akai should be outputting at line level, and if your plugging into
a motu at line level (and) your Akai is outputting a signal at almost zero db.
I'm not sure why you'd have to add 20+ or 20db of gain on the motu.

if your akai only outputs unbalanced line then only use a mono cable.
if it outputs balance line, then make sure your motu is using a stereo jack and isn't set somewhere to be using a balanced microphone setting.
e.g. XLR microphone. also make sure any phantom power is off.

these do most of what is needed for testing.
http://lashpapa.info/pyle-pro-pct40-...le-tester.aspx