High pitched whistle with a digital pedal

[Osiris]

Digging around in my odds and sods box earlier I found my old Alesis Smashup digital compressor and thought I'd have a play with it having not touched it for years. When plugging it in everything appears to be working fine but there there is a persistent high pitched whistle while using it and what sounds like a sort of Morse code tapping underneath it too, which from what I can gather online is digital clock noise (although I have no idea what that actually means!). Further looking online suggests that the issue is the power supply not being isolated, but I'm using the original Alesis power supply that came with the pedal, I'm not using it with any other pedals, it's just bass into the Smashup into my amp. It's worth noting that the pedal is sat on top of the amp in case this makes a difference. The amp and the pedal are plugged into the same multi gang socket. I've tried to power it using a different power supply but it appears to have an odd sized connector, my 9V Boss adaptor being too big to fit. I've also tried other cables but to no avail. 

Anyone have any thoughts as to what I can do to resolve this? Or is the pedal had it? Be shame if it has as it's a great sounding unit.    

[itu]

Alesis uses 9 VAC very often. It may be the reason for the odd sized connector.

[dannybuoy]

If it's 9V DC and under 800mA, this might do the trick, worked well for me when I had a similar situation:

https://www.amazon.co.uk/JOYO-ZGP-Guitar-Effect-Supply/dp/B07CS6T95Z

[paulbuzz]

An ugly noise identical to your description is mentioned in the Ovnilabs review of the Alesis Smashup, so maybe it's just an inherently flawed design...?

http://www.ovnilab.com/reviews/smash.shtml

[Osiris]

Cheers folks,

@dannybuoy does the Joyo filter have standard Boss sized connections (I can't remember the actual size but the industry standard size for pedal power connections)? If it does it won't fit due to the different sized connector, which could be because it's AC as @itu says. 

Thanks @paulbuzz Yes, it sounds like the same issue described on the Ovnilabs review. I must have had this for around 15 years, and although I haven't used it for years because I'd forgotten I had it, it had never made the whistling before. 

[Woodinblack]

1 hour ago, Osiris said:

Cheers 

@dannybuoy does the Joyo filter have standard Boss sized connections (I can't remember the actual size but the industry standard size for pedal power connections)? If it does it won't fit due to the different sized connector, which could be because it's AC as @itu says. 

They are standard connectors, I use one with my smoothhound (after a polarity changer)

 

[paulbuzz]

Here's the manual for the Smashup:
https://www.noisefx.com/docs/Alesis_ModFX_Smashup_Reference_Manual.pdf

The power supply provides 9V AC - From p17 of the manual:
The Smashup comes with an AC power adapter that transforms the voltage from a standard outlet into 9 volts AC (830 mA)
So don't try using a normal DC power supply as an alternative!

The manual also contains some info about dealing with "stray hums and buzzes" between pages 37 and 40 (!)
I think that this does tend to imply that this model is a bit prone to this kind of problem!

[Osiris]

5 hours ago, Woodinblack said:

They are standard connectors, I use one with my smoothhound (after a polarity changer)

 

Cheers, I guess that rules the Joyo out?  It also looks like it's for a DC voltage, would that even work with AC? This isn't something that I understand! 

Thanks again @paulbuzz. I read the relevant sections of manual and tried moving and swapping cables but it's still whistling, unfortunately. 

 

Does anyone know if something like this would work? The blurb mentions eliminating AC hums and hisses, although my issue is not what I'd call a hum or hiss but a whistle with an underlying tapping or drumming sound. 

https://www.gear4music.com/Recording-and-Computers/SubZero-Hum-Destroyer/27BH?origin=product-ads&gclid=EAIaIQobChMItufu4_Cv5AIVBrDtCh0L0A9kEAQYByABEgJqb_D_BwE

Could it be worth a punt for the money?

 

If not, I guess my options are;

1. Live with it, it's only my little practice rig, and you don't really notice when playing, only when there's a gap. 
2. Buy another suitable AC power supply. But I guess that this won't necessarily solve the issue?
3. Play without the Alesis. But the dbx model sounds so big and punchy that I'd miss it too much!
4. Get another compressor pedal. 
5. Play without a compressor. No. Not an option 

[Woodinblack]

13 minutes ago, Osiris said:

Cheers, I guess that rules the Joyo out?  It also looks like it's for a DC voltage, would that even work with AC?

It is dc only, sorry I missed you wanted AC. The only reason I said about the polarity converter is the smoothhound is backwards

13 minutes ago, Osiris said:

Does anyone know if something like this would work? The blurb mentions eliminating AC hums and hisses, although my issue is not what I'd call a hum or hiss but a whistle with an underlying tapping or drumming sound. 

That is exactly what it is for

[Osiris]

Cheers @Woodinblack, I'll order one and see what happens. 

[itu]

If the unit's powering scheme supports DC, it may work. Still I would not try that without carefully studying the unit. Besides, 9 VDC may not be enough.

[Woodinblack]

Now I have read your original post, it will not help you (sorry, I was sitting in exeter high street waiting for my wife to come out of lush when I replied before). It helps in the situation where you have a shared power supply, and the digital noise gets on the power going to the other effects.

If you have it sat on your amp, that is the first thing to change.

[Osiris]

OK, thank you. Good job I didn't rush in to ordering one in that case!

I was trying a few things earlier, I even moved the pedal to the next room and ran it into the amp with a 6 meter cable, but it's still whistling. Also tried swapping cables and even a different bass but I still couldn't get rid of the noise.

Looks like it might be time to get something to replace it. Unfortunately, the Smashup is no longer made, which is a shame as it has some great sounds in it. Ah well. 

[Woodinblack]

So what is the input to that compressor? Is it direct from an active bass? That could be another issue

[Osiris]

No, I've only tried this with passive basses, neither of which have hot outputs. There is also an input trim pot on the Smashup, the optimum position for this so that it doesn't clip is around 80% open, but even with the trim set at minimum the whistling is still audible. I even tried it with no bass plugged in and the cable removed and it was still doing it! 

[MoonBassAlpha]

Might be worth checking the soldering of the sockets to the board. if the ground has disconnected you might well hear just this. PCB mounted sockets can be prone to this. Both my old Zoom multitrack recorders had this on the headphone socket, an annular fracture of the solder round the pin.

[Osiris]

Thanks @MoonBassAlpha it's something to investigate. Our keyboard player is an electronics engineer, I'll ask him if he wouldn't mind taking a look.