What's new
By:

Loud thump sound when I turn on my NNC. Any tips for fixing?

BuddyC

BuddyC

Enlightened
Joined
Sep 17, 2018
Messages
936
Reaction score
3,190
Location
Oslo, Norway
I got 2 New Net City’s at home.
Both work excellent and are identical as far as speakers, Sega amp, original wiring etc etc.
One is quite silent when I power on, the other one makes a loud THUMP sound. Just like turning on a old guitar/bass amp.

Not a big issue since everything is working as it should, but I am curious on why one of them makes this thump/pop sound since they both look identical as far as I could tell.

Anybody else got a ”thumper”?
 
Yeah, one of my net cities is. Never thought much of it... it has the bigger lindy style SUN PSU as opposed to the "normal" SUN in my other cab.

I never checked to see if perhaps the audio amps are different revisions or something, but it's been this way for many years (since I got it) so I just kinda stopped caring.
 
Does it happen only when you turn on the cab, or also when you turn it off?

it could be a few things, some are:

Ground issue between amp/cab/source
Amp turns on before the source or turns speakers on immediately when powered (the thump is most likely the result of high voltage spike), a simple 3-5 second delay circuit could solve that.
If there are any gain pots on the amp, they are set too high
 
Got the cab around 3 years ago and it has never been an issue, but find it quite interesting since audio amps are same revision and recaped. As is SUN PSU.
Weird.
 
Derick2k said:
Does it happen only when you turn on the cab, or also when you turn it off?

it could be a few things, some are:

Ground issue between amp/cab/source
Amp turns on before the source or turns speakers on immediately when powered (the thump is most likely the result of high voltage spike), a simple 3-5 second delay circuit could solve that.
If there are any gain pots on the amp, they are set too high
Click to expand...
No gain pots as far as I know on these amps. It makes a small thump when I turn it off, but the thump is way louder at power on. No other audio issues or “humming“ sounds that indicate ground issues after power on.

I know some use a delay circut on car stereos, so that could be a potential fix.
 
My NNC does a bit the same, never thought much off it, also original Sega amp etc.
2 weeks ago I recapped both the sound amp and the PSU and no change, so I think it might be 'normal', perhaps the thump comes from when the high voltage of the monitor is turned ON?
Possibly you could try unplugging the power from the monitor and turn the cab ON/OFF then and see if anything changes?
 
All NUCs that I worked on do that. I think it is normal for these cabs.
 
nnap said:
All NUCs that I worked on do that. I think it is normal for these cabs.
Click to expand...
Probably normal, but I have worked on 4 New Net City’s and this is the only one that’s really fucking loud at power on.

I might have a go with a delay circuit. Could be a fun experiment.
 
BuddyC said:
Probably normal, but I have worked on 4 New Net City’s and this is the only one that’s really fucking loud at power on.

I might have a go with a delay circuit. Could be a fun experiment.
Click to expand...
ya - in other cases a delay circuit like this aliexpress.com/item/32716030330.html was used to solve the "problem".
my NUC makes a sound pop as well btw.
 
You must log in or register to reply here.
Back
Top