Yet another power question

FruitarGeek · 2010-07-31T14:37:43+00:00

So, whilst the forum is on the topic of power, I have a quick question So my current power supply is the Boss AC Adapter (PSI 230s) or something like that,...

Yet another power question

AlanRatcliffe

Yes, it will work. Just be aware the more pedals you add - especially different makes - the more chance of picking up earth loops.

FruitarGeek

Alan Ratcliffe wrote: more chance of picking up earth loops.

Im no electrician, but I'm guessing that means it will be noisy? Should that happen, I could fix that problem by getting a proper power supply right?

AlanRatcliffe

Yeah - it'll hum. How much depends on the pedals involved. A good power supply with isolated outputs for each pedal will fix it.

FruitarGeek

Cool.

Thanks Alan

FruitarGeek

Sorry, before I foget

Does a daisy chain split the power evenly i.e. if my chain has 5 outputs and is connected to a 500ma power source, does that mean each output will only give 100ma? or is it dependant on how much power the pedals such?

The reason I ask is, most boss pedals are below 50ma so the rules of 100ma per channel works fine, but I wanna get a DD-20 which takes 200ma and I want to know that a single daisy chain can handle that!

TomCat

If you do daisy chain then work in descending order of current draw if possible. In your case have the DD-20 closest to the PSU.

AlanRatcliffe

A daisy does not limit the current to any of the plugs, so if you want 200ma on one plug and 50 on another, there should be no problems doing so.

TomCat wrote: If you do daisy chain then work in descending order of current draw if possible. In your case have the DD-20 closest to the PSU.

Why is that Tom? Cable resistance?

VetGat

yes you can do that with your dd-20 but do as tom says and put it closest to your power supply..
another thing-most people dont realise that the tu2 and the new tu3 are power supplies on there own. so before anyone buys a second power on a complicated board, just check first because if you have one of those pedals, you are much more than sorted

matta

Nope, the TU2 only has a THROUGHPUT it has not supply of it's own at all... all the extra jack does is pass the power on from the connected power source.

Cheers

Matt

Christo de la Rey wrote: yes you can do that with your dd-20 but do as tom says and put it closest to your power supply..
another thing-most people dont realise that the tu2 and the new tu3 are power supplies on there own. so before anyone buys a second power on a complicated board, just check first because if you have one of those pedals, you are much more than sorted

TomCat

Alan Ratcliffe wrote: A daisy does not limit the current to any of the plugs, so if you want 200ma on one plug and 50 on another, there should be no problems doing so.

TomCat wrote: If you do daisy chain then work in descending order of current draw if possible. In your case have the DD-20 closest to the PSU.
Why is that Tom? Cable resistance?

Yup.Ground loop noise is directly related to ground currents. The ground in the daisy chain lead has resistance and if you draw higher current down the lead at the farthest point then all other devices (Pedals) are not at ground potential and therefore susceptible to hum...

One of my favorite little peeves is the often high neutral/ground voltages often present in building's power reticulation, causing great fun and games to audio and video/AV equipment.

AlanRatcliffe

TomCat wrote: Yup.Ground loop noise is directly related to ground currents. The ground in the daisy chain lead has resistance and if you draw higher current down the lead at the farthest point then all other devices (Pedals) are not at ground potential and therefore susceptible to hum...

Makes sense, but I wouldn't think the resistance in the cable would be anywhere near enough to cause an issue.

One of my favorite little peeves is the often high neutral/ground voltages often present in building's power reticulation, causing great fun and games to audio and video/AV equipment.

Amen.

TomCat

Alan Ratcliffe wrote:
TomCat wrote: Yup.Ground loop noise is directly related to ground currents. The ground in the daisy chain lead has resistance and if you draw higher current down the lead at the farthest point then all other devices (Pedals) are not at ground potential and therefore susceptible to hum...
Makes sense, but I wouldn't think the resistance in the cable would be anywhere near enough to cause an issue.

The way I see it is that the overall impedance's in guitar lines etc is quite high when going into the amp so there is not much there to swamp out noise currents (unlike low impedance microphones for example) so for me any way of giving the signal a better chance of survival is important. By having higher currents drawn over shorter lines in a daisy chain arrangement should drop the level of noise/hum in the pedal chain.

However, when the power is distributed in a star configuration as from a centralised power supply, only one ground reference is used and all ground voltages are references back to the same point, theoretically meaning that each pedals' ground voltage is identical and therefore zero relative to each other....i.e....no hum/noise.

Parting shot....the noise/hum referred to here relates to grounding issues. This will not fix a noisy pedal in the chain as the noise will usually relate to gain (Electronic Noise) and not the grounding conditions.