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 Post subject: noise/hum question about the sp-404sx
PostPosted: Mon Nov 06, 2017 2:38 pm 
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hi all,

I've a question - I was trying to sell my sp-404sx (keeping my beloved 303), and a guy I sold it to me returned it because he noticed a hum/background noise in it, and decided he couldn't use it for that reason. I replied to him that some hum is common in any device which outputs audio, you can't expect it to be fully silent, and that also he might check if it was affected by the power grid, or by other devices on the same power outlet. But in the end it didn't help, so I got the machine back.

I tried it myself, to see if I noticed any difference from when I used the machine myself (which was a while ago)... I don't think there's a difference, but it's true there is a noticeable hum, but it doesn't get recorded when you sample and resample. So I figure it only occurs in the output, and not in the data that the machine works with. (Which makes sense I guess.)

The funny thing is that the hum only occurs when the volume is somewhere in the middle - it's inaudible when volume is all the way down, and it also disappears when you turn the volume all the way up (when not playing samples, of course).

I was wondering, can other SX users confirm this same behaviour or is it different? I think I will put the machine back up for sale without mentioning this, if it's not specific to this machine.


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Mon Nov 06, 2017 6:10 pm 
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I hate to say it, but I've never heard a hum or any noise with my 404sx, it's really clear (I got it about 2 years ago & use it DAILY). When adjusting the volume it crackles a little, but as long as I don't touch the volume knob it's fine. Crystal clear.


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Mon Nov 06, 2017 11:33 pm 
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might be a grounding issue . I'm no electrician, but its the only conclusion I can come up with. might need to take a look at the unit (if you know circuitry . or someone who does) could just need to remove the cover and clean the ports .

is there an input source connected that's turned off?

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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Tue Nov 07, 2017 12:30 pm 
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This only happens on my 404sx also, The hum appears only if the ext source button is turned off...
And it also sounds strangely weird..


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Sat Nov 11, 2017 2:55 pm 
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Thanks for your replies, all. I guess it could use being looked at, in a repair shop which does audio gear in general. But I don't want to spend a lot for a machine which I intend to sell. I'll probably try and sell it and be upfront about it, have people come by and try it out.

I know for a fact that this machine hasn't ever been 'crystal clear' so perhaps I should have used the warranty when I still had it. I actually never thought much of it, but I do think that my 303 is more silent than the 404sx. Might be another reason why I like the 303 better.

thanks again for the feedback.


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Sat Nov 11, 2017 3:03 pm 
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THEGREAT wrote:
might be a grounding issue . I'm no electrician, but its the only conclusion I can come up with. might need to take a look at the unit (if you know circuitry . or someone who does) could just need to remove the cover and clean the ports .

is there an input source connected that's turned off?


Thanks, I will try out if this makes a noticeable difference, but I've never noticed that before.

Last time I tested, I had it connected to the headphone out of the living room amplifier, which is connected to other devices which are plugged into the wall socket and turned off. Only the record player is grounded to the amp, and the amp itself I think isn't grounded. Previously I've tested the SP connected to my laptop running on batteries, and by itself, sampling the audio out from my telephone.


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Mon Nov 13, 2017 1:32 am 
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Just got a used sx and i got this problem too. The buzz goes away when i press ext source(sometimes other buttons) and comes back when i press a pad or turn a knob. It wouldn't be a big deal cause it's super low, but i really wan't to run 404 stuff through the 303 vinyl comp and when i do that the buzzing is annoing af :cry: i tried it on batteries away from my computer and stuff, but it's still there. If anyone have been able to fix this or got some workaround i would be so gratefull


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Tue Jan 16, 2018 10:42 pm 
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I have this issue with a brand new 404sx that I got for Christmas. I have discovered that the output in the headphones is very clean, but output from the Line Out buzzes horribly as soon as something is displayed on the display. For example, if I play a sample it buzzes/hums. Stop the sample, with tempo or other details on the display, it buzzes. Hit the external button (dashes appear on the display) and the buzz is gone. Move a dial or launch a sample (so something appears on display) and buzz is back. Driving me crazy! Is this normal?


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Tue Jan 16, 2018 11:10 pm 
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DYMS wrote:
I have this issue with a brand new 404sx that I got for Christmas. I have discovered that the output in the headphones is very clean, but output from the Line Out buzzes horribly as soon as something is displayed on the display. For example, if I play a sample it buzzes/hums. Stop the sample, with tempo or other details on the display, it buzzes. Hit the external button (dashes appear on the display) and the buzz is gone. Move a dial or launch a sample (so something appears on display) and buzz is back. Driving me crazy! Is this normal?


Damn. I got my 404SX brand new and never encountered this. maybe this is fixed with the 404A?

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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Wed Jan 17, 2018 12:09 am 
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thesisdrs wrote:
Damn. I got my 404SX brand new and never encountered this. maybe this is fixed with the 404A?


Thanks for confirming that for me. Probably gonna have to take it in for a repair or warranty claim.


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Wed Jan 17, 2018 5:36 am 
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have kind of a similar problem, but not as bad. since I've had my 404sx, when I power it on, I hear a very high pitched hum noise, but its not very loud. However, it only hums when the volume knob is all the way down. When the volume knob is at 12 o 'clock or louder, i don't hear the hum at all. Its not as big of a deal for obvious reasons but its still annoying, because I hear it everytime i turn it on.

THEGREAT wrote:
might be a grounding issue . I'm no electrician, but its the only conclusion I can come up with. might need to take a look at the unit (if you know circuitry . or someone who does) could just need to remove the cover and clean the ports .


if anyone knows a proper way to clean the correct parts on the 404sx to get rid of a hum, let us know!


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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Sat Feb 24, 2018 6:02 am 
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it shouldn't be hum, but hiss. if any sampler is turned up too loud with no audio being played you will hear white noise, just like the noise floor of records or tape hiss or whatever. it should never make any hum (which usually specifies a single frequency or note of sound that gets played in mix with the hiss) this is only caused in record players that are poorly grounded as they catch interference and shit i think but a hum wouldn't be generated by a sampler unless it was damaged i guess?

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 Post subject: Re: noise/hum question about the sp-404sx
PostPosted: Sat Feb 24, 2018 6:03 am 
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btw all computers make hiss that's nasty af from the soundcard if you turn up the speakers

if you turn up any speakers connected correctly to anything you will get lots of hiss

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