will this AC adaptor solve my hum problem?

[ShowKing]

hey guys,

my chain goes like this:

bass -> overdrive -> chorus -> preamp/di -> amp

my basses are active.
the preamp/di pedal is going by battery and no AC adaptor.
the overdrive and chorus are the only pedals i'm using with an AC adaptor that is daisy chained.

the adaptor i use can be set at different volts. obviously i have mine set at 9V for the 2 pedals.
and its 500mA. the pedals require 200mA each so its sufficient.

i noticed with this AC adaptor, there is an annoying hum coming from the amp.
when the pedals go by batteries only, its perfectly quiet so i came to the conclusion that the adaptor is the cause.

after doing search here, i decided that most ppl seem to be happy using the 1 spot AC adaptor.
will this solve the annoying hum?

i found this very cheap 1 spot on ebay
http://cgi.ebay.com/9VDC-1A-Wall-Ada...3A1|240%3A1318

but it's unusually cheaper than all the other 1 spot by visual sound on ebay like this one
http://cgi.ebay.com/VISUAL-SOUND-ONE...3A1|240%3A1318

i just want some help verifying if the cheaper adaptor is the same as the more expensive one?
and lastly, i need to use a different plug because the plugs here are different. will that affect anything?

thanks

[JustDavid]

All you need is something to adapt the connection type; you don't need to transform any 'wall current' within 100 to 240 Vac.

Cheap one supplies 1.0 amps, OneSpot 1.7 amps.
Cheap cord 4.5', OneSpot 10'.
Both work on 100-240 Vac. Cheap 50 or 60 Hz, & I'd presume the OneSpot also.
Cheap has a LED (blue!!). OneSpot none.
Cheap is $13 to US. OneSpot is $24.
Cheap one's cheap. That MIGHT mean it can pass more noise on it's output.


I'd go for the OneSpot, mostly for the reduced CHANCE of noise. I do like the 10' cord too.

[4StringsEnough]

That cheap one won't work. It's centre positive when you need centre negative. And it's 2.5mm when you need 2.1mm. Does NZ have the same socket type as Australia? If so, why not look at this.

It's a bit more expensive, but it's more powerful and has the daisy chain built in. It's got the right plug socket for you and, importantly, it's 2.1mm centre negative! I use the UK version and couldn't be happier!

[ShowKing]

Originally Posted by 4StringsEnough

That cheap one won't work. It's centre positive when you need centre negative. And it's 2.5mm when you need 2.1mm. Does NZ have the same socket type as Australia? If so, why not look at this.

It's a bit more expensive, but it's more powerful and has the daisy chain built in. It's got the right plug socket for you and, importantly, it's 2.1mm centre negative! I use the UK version and couldn't be happier!

yes i believe its the same in NZ.
hmm that adaptor does look promising.

do you guys know the cause of AC adaptor hum?
because i have no clue what the reason is behind it.

[4StringsEnough]

Originally Posted by sungjin891118

do you guys know the cause of AC adaptor hum?
because i have no clue what the reason is behind it.

If it's a hum rather than a squeal then it's most likely because you've got an unregulated power supply.

Also, about the plug types, Aus and NZ do have the same sockets according to this site.

[ShowKing]

Originally Posted by 4StringsEnough

If it's a hum rather than a squeal then it's most likely because you've got an unregulated power supply.

Also, about the plug types, Aus and NZ do have the same sockets according to this site.

yeah the power supply i been using is from an electronic shop. no problems with a single pedal but when i daisy chained 1 more pedal, i noticed the hum.

i think i will purchase that adaptor u've shown me.
it's nice to know someone else has had success with it already

[niftydog]

Originally Posted by sungjin891118

do you guys know the cause of AC adaptor hum?
because i have no clue what the reason is behind it.

There are two main causes, poor quality filtering and a phenomenon called "ground loops".

Best to start with a good quality, regulated power supply. I suggest you avoid the mains plug adapter scenario and just buy something meant for the AUS/NZ market - like this. Jaycar has three stores in Auckland.

It seems as if you already have a daisy chain so I wouldn't waste your money on that eBay one - especially since with postage it looks like costing you over $50!!!

As for ground loops, there's an easy way to test for this. First try this; make sure there's a battery in both the pedals being powered by the adapter. Then, when you've got everything plugged in and you're hearing the hum, unplug the DC plug from ONE of the pedals, leaving just the one other pedal being powered by the adapter. If the hum goes away then you might have a ground loop.

Another test would be to have both pedals connected to the power adapter, but only have ONE of them connected in the signal path. This puts the same load on the power supply, but doesn't allow a ground loop to form. (You must have a spare patch cable plugged into the input of the 'out of signal path' pedal so that it turns on.)

There's no guarantee that simply buying another power supply will fix your problem, even if it comes recommended by other users.

[ShowKing]

Originally Posted by niftydog

There are two main causes, poor quality filtering and a phenomenon called "ground loops".

Best to start with a good quality, regulated power supply. I suggest you avoid the mains plug adapter scenario and just buy something meant for the AUS/NZ market - like this. Jaycar has three stores in Auckland.

It seems as if you already have a daisy chain so I wouldn't waste your money on that eBay one - especially since with postage it looks like costing you over $50!!!

As for ground loops, there's an easy way to test for this. First try this; make sure there's a battery in both the pedals being powered by the adapter. Then, when you've got everything plugged in and you're hearing the hum, unplug the DC plug from ONE of the pedals, leaving just the one other pedal being powered by the adapter. If the hum goes away then you might have a ground loop.

Another test would be to have both pedals connected to the power adapter, but only have ONE of them connected in the signal path. This puts the same load on the power supply, but doesn't allow a ground loop to form. (You must have a spare patch cable plugged into the input of the 'out of signal path' pedal so that it turns on.)

There's no guarantee that simply buying another power supply will fix your problem, even if it comes recommended by other users.

i've done the test u've told me, and when i plug the DC out of one of the two pedals, the hum is gone.
i guess this means i have a ground loop which i dont know what that means.

this adaptor (same as ebay) seems to be my best choice at the moment, it's available in same plug as aus/nz.
the only issue is i've already got a daisy chain, but i can easily sell it because i still have the packaging and i only got it yesterday for free.
http://www.effectpowersupplies.com/9...-chain-2-p.asp

[niftydog]

The adapter on ebay will NOT fix your ground loop problem. The cause of the ground loop is effectively the daisy chain, and the adapter you linked to above is nothing more than a glorified daisy chain. DON'T WASTE YOUR MONEY!!

I would suggest you also do the second test I mentioned just to be sure that the power supply isn't becoming noisy when you load it up with both pedals.

As to what a ground loop is, the simple explanation is that noise can be created when two devices share the same ground connection - particularly when the ground connection is of a particular configuration as found in ALL daisy chains.

The cheap solution is to make (or modify) a patch cable with the shield only connected at one end. Put that between the two pedals on the daisy chain and let us know how you go.

[ShowKing]

Originally Posted by niftydog

The adapter on ebay will NOT fix your ground loop problem. The cause of the ground loop is effectively the daisy chain, and the adapter you linked to above is nothing more than a glorified daisy chain. DON'T WASTE YOUR MONEY!!

I would suggest you also do the second test I mentioned just to be sure that the power supply isn't becoming noisy when you load it up with both pedals.

As to what a ground loop is, the simple explanation is that noise can be created when two devices share the same ground connection - particularly when the ground connection is of a particular configuration as found in ALL daisy chains.

The cheap solution is to make (or modify) a patch cable with the shield only connected at one end. Put that between the two pedals on the daisy chain and let us know how you go.

i've done ur 2nd test.
the pedal that isn't connected in the pedal chain made no difference with the adaptor in or out.
so what does this mean?

but even with one pedal with the adaptor, there is a hum.
its a quieter hum but it's there as long as the adaptor is in.

i think i need to buy a regulated adaptor for effect pedals

[niftydog]

Originally Posted by sungjin891118

i've done ur 2nd test...
so what does this mean?

It means you definitely have a ground loop. The 2nd test checks how the power supply performs - some power supplies will get noisy when you load them down - this one seems to be just fine.

You said you bought it at an electronics shop, was that Jaycar or something like that? Can you look it up to find out if it's regulated or not? You may already have a regulated supply!

Originally Posted by sungjin891118

but even with one pedal with the adaptor, there is a hum.
its a quieter hum but it's there as long as the adaptor is in.

A small amount of hum is not unusual with most power supplies - if you can live with it at that quieter level then I'd just stick with what you've got and fix the ground loop with the modified patch cable I mentioned.

[ShowKing]

Originally Posted by niftydog

It means you definitely have a ground loop. The 2nd test checks how the power supply performs - some power supplies will get noisy when you load them down - this one seems to be just fine.

You said you bought it at an electronics shop, was that Jaycar or something like that? Can you look it up to find out if it's regulated or not? You may already have a regulated supply!


A small amount of hum is not unusual with most power supplies - if you can live with it at that quieter level then I'd just stick with what you've got and fix the ground loop with the modified patch cable I mentioned.

i just found out my AC adaptor is unregulated
i got it from dick smith. brand is "digitor"

here it is:

http://www.dse.com.au/cgi-bin/dse.st.../product/M9647

[niftydog]

Ok, something like this or better yet the Jaycar one will be just fine, and potentially slightly less noisy, but neither will fix the ground loop issue.

[Nyarlathotep]

Originally Posted by niftydog

The cheap solution is to make (or modify) a patch cable with the shield only connected at one end. Put that between the two pedals on the daisy chain and let us know how you go.

I was under the impression that daisy chain cords were 2 wire (basically) 1 for the center/pin and one for the barrel/sleeve. Is there a 3rd layer for shielding that some companies might inadvertently connect to the barrel or something?

[niftydog]

I'm talking about signal patch cables - sorry, that wasn't made clear.

[4StringsEnough]

Originally Posted by sungjin891118

but even with one pedal with the adaptor, there is a hum.

IMHO, you've not got a ground loop. They normally come where you've got the same power supply connected both to effects placed before the front end of your amp as well as to effects in the effects loop. They can also happen when using a vintage amp or one where the grounding is dodgy.

From everything you've described, the hum you're experiencing is entirely due to using an unregulated power supply. A regulated power supply like the Jaycar one with your existing daisy chain or the Ebay one I linked to should operate silently.

[Nyarlathotep]

Originally Posted by niftydog

I'm talking about signal patch cables - sorry, that wasn't made clear.

LOL

Had me wondering what kind of adapters you guys have down there

[ShowKing]

Originally Posted by niftydog

Ok, something like this or better yet the Jaycar one will be just fine, and potentially slightly less noisy, but neither will fix the ground loop issue.

i tried my guitarists AC adaptor which he got from the guitar shop and it sounded like there's no hum

[vin*tone]

Originally Posted by 4StringsEnough

IMHO, you've not got a ground loop. They normally come where you've got the same power supply connected both to effects placed before the front end of your amp as well as to effects in the effects loop. They can also happen when using a vintage amp or one where the grounding is dodgy.

From everything you've described, the hum you're experiencing is entirely due to using an unregulated power supply. A regulated power supply like the Jaycar one with your existing daisy chain or the Ebay one I linked to should operate silently.

I'm interested to see how the Jaycar adaptor works. It's a switchmode PS - similar to the OneSpot - which are apparently really quiet. That cheap $8 ebay one is also switchmode so ironically could also be really good.

*! There's a difference between "regulated" and "filtered". A regulated supply will put out its specified voltage no matter what appliance(s) are plugged into it. Most cheap adaptors are "unfiltered". ie: has a certain amount of AC signal bleeding through with its DC (eg Dick Smith Digitor adaptor!!). This is cool for most appliances- razors, battery charger etc... but NOT good for audio .

A filtered supply will likely have a capacitor bridging across the terminals which allows all AC signal to short directly to ground leaving pure DC.

[vin*tone]

BTW...

This ad is flat out misleading. The seller's called it a "1 spot" bc it takes up one spot on the board. Note there are no shots of the top.