Weird horrible sound with Series II electronics and IN-2

[edwin]

I've had a couple of episodes now where I plug my bass into an IN-2 and everything sounds good, then I switch the bass to standby and when I switch it back, I get a horrible broadband noise out of the bass. If I turn down the master volume on the bass it goes away, but if I run the bass off the batteries, it works fine. I've checked the wiring of the bass and it seems like there's not much to go wrong with the IN-2, so I'm not sure where to start. Could the power module in the IN-2 be failing? I always assumed it would work or not.


Ideas?

[JimmyJ]

That's an odd one, and the worst kind of problem because it's intermittent.    Do you have a DS-5 you could try to see if you can recreate the issue?  I agree that it seems unlikely it would be the IN-2's power module failing. 

"Standby" mode simply shorts the audio outputs of the onboard preamps so it's unrelated to the power supply or current the bass is drawing.  The preamps are still running.  That makes me wonder if you might be losing a component on the board?  Can you say if the noise appears to be coming from both pickup channels?  If so... hum canceller channel opamp or FET?  (Because that signal appears in both channels).  Just my uneducated guess.

I'd probably open up the electronics cavity and tap around on the preamp board with a pencil or something to see if anything makes noise.

Let's see what other ideas come through and hopefully we can get to the bottom of it.

Jimmy J

[edwin]

Thanks for the reply, Jimmy. I would think that if it were a component on the board failing, then I'd get same problem when running off batteries.

Yes, it is both pickups. Weirdly, with the 5 pin cable unplugged from the IN-2, I still get some noise I wouldn't expect. I'll poke around some more and see if it does it with my DS-5.

[sonicus]

https://www.acopian.com/   
ACOPIAN sold me a new power module several years ago for my failed IN 2 .

It shall be of paramount importance to measure your internal clearance to accommodate their current production availability and comply to ALEMBIC power requirements for the + / - voltage.

[edwin]

Of course, now I can't get it to make the sound. I had it wired up and poked the wiring with a chopstick and it sounded perfect. Hm. Maybe my 5 pin cable? It does sound like it could be a grounding issue, although it's much more than a hum.

[edwin]

https://www.acopian.com/   
ACOPIAN sold me a new power module several years ago for my failed IN 2 .

It shall be of paramount importance to measure your internal clearance to accommodate their current production availability and comply to ALEMBIC power requirements for the + / - voltage.

Good to know. Do you happen to have a record of the model number? They seem to have a huge selection.

[cntrabssn]

Of course, now I can't get it to make the sound. I had it wired up and poked the wiring with a chopstick and it sounded perfect. Hm. Maybe my 5 pin cable? It does sound like it could be a grounding issue, although it's much more than a hum.

Edwin, you might have tried this already, but could there be a correlation between the occurrence of the noise and how long the bass is in standby? In particular, if the bass is in standby for a longer period of time (e.g. minutes)?


Checking the cable is always a good idea.

[edwin]

Of course, now I can't get it to make the sound. I had it wired up and poked the wiring with a chopstick and it sounded perfect. Hm. Maybe my 5 pin cable? It does sound like it could be a grounding issue, although it's much more than a hum.

Edwin, you might have tried this already, but could there be a correlation between the occurrence of the noise and how long the bass is in standby? In particular, if the bass is in standby for a longer period of time (e.g. minutes)?


Checking the cable is always a good idea.

Yes, I thought about this and have tried various times of standby. My recollection is that the bass wasn't in standby for more than a minute or two when it happened. I've got this all set up at home and have been playing it all week and it seems to be fine.

[edwin]

Update: I cannot make it make this noise and it has performed perfectly at subsequent gigs (and in my basement). Oh well. It's weird.

[JimmyJ]

Well, I guess that's good news, but not very comforting.  We hope it has cleared itself up.

You described the noise as "broadband".  Do you mean like a pink or white noise, like a roar?  Or was it an oscillation like the scream that we can sometimes get out of our filter circuits? 

Are you using a different 5-pin cable now?  Did you also exercise the switches on the IN-2 (doubtful but...)?

Again, we'll hope that was a one-time thing and the gear was just trying to get your attention.   

Jimmy J

[edwin]

It was like pink noise, except darker. Definitely not an oscillation.

Same cable.

I did exercise the switches, but I don't see how that would make a difference.

One thing I did was tighten up the 5 pin jack on the bass. The wires were all fine and not shorting out, so it shouldn't have made a difference, though, and it was working before I did that.

Thanks for the suggestions!

Edwin

[BeenDown139]

in my tech days that solution was referred to as the laying on of hands.

myself, i hate problems that solve themselves.