Daisychain 9V on Ring of TRS Cable

[mth5044]

Has anyone experimented with passing along power through pedals on the ring of a TRS plug? Power the first pedal, use stereo jacks and send power along the audio cables? I know I didn't come up with this idea - I'm pretty sure I've seen someone say something about it on here before - but I can't seem to find any mention of it. Could free up space on the enclosure so one wouldn't need a power jack. Could be a problem if you ever got rid of that first pedal, but it would be simple to make a small box that had a power input as well as guitar in and a TRS out.

[Seljer]

I think the issue here is that then you'd then have ~1mm between the signal conductor and the power rail through all of your inter-pedal connections. Which is an excellent opportunity for any 50hz hum, LFO ticks and other pests to find ways back into the inputs of pedals and make themselves even worse through strange feedback paths.

[Levispeights]

Hmm... Really cool idea though!

[R.G.]

Sadly, this practically guarantees that any possible interference and noise from pedal-to-pedal grounding issues is as bad as it can be.

The very high gain of many pedals and the high input impedance of nearly all of them make the very, very prone to grounding issues.

Sure it will work. It is prone to giving you unwanted hitchhikers, too.

[pappasmurfsharem]

Not to mention all your patch cables would have to be TRS =(

[alanp]

Not to mention all your patch cables would have to be TRS =(

This is the huge problem -- a normal TS plug, and one tired moment where you're not entirely "with it", or one stupid bogan wanting to impress you, and watch the smoke escape.

[Processaurus]

I believe EBS actually did a system like that, where their bass heads would put 9v on the ring connections and you could plug in a pedal with a trs cable.

This is the huge problem -- a normal TS plug, and one tired moment where you're not entirely "with it", or one stupid bogan wanting to impress you, and watch the smoke escape.

The 9v would definitely have to be current limited, and forgiving of being shorted out for hours, if not days, but that technology is there.  I think One Spots, for example, will safely shut down when the output is shorted, and runs through a cycle, testing the output to see if it is still shorted out repeatedly.  Whether this cycle causes gross noise in the audio is another matter.

RG brings an interesting point, that it mixes signal ground and sewer ground into the same conductor, but... any set of daisy chained pedals where each directly connects the power (-) to the chassis and signal ground does that already.  Power (-) and signal ground are being stitched together down the chain of pedals.  It might work fine, in situations where the daisy chained pedal power would have worked.  One plus you'd have going for you is that the sum of all of the braided copper shield on a heavy guitar cable amounts to a somewhat hefty conductor.

It may have been RG who suggested, a long time ago, switching from 1/4" jacks and cords to USB cables on a pedal board, so power could be in the same cable!

[Gus]

Something I posted in the past

[brand0nized]

What if you made a huminator like this one?

http://www.madbeanpedals.com/forum/index.php?topic=3316.0

You could build it with a guitar input, and instead of a 9V out, connect it to the ring output.

[mth5044]

I guess there are a few flaws 

Gus - your image loads on neither my computer or my phone. Unsure what it is!
brand0nized - I don't have access to that forum  Guess I'll have to sign up.

[brand0nized]

No need to fear! Youtube is here! Great forum, though!

Maybe you could use this or any type of power filter/regulator circuit out there.

[MrStab]

i'm surprised no-one has mentioned this already (or maybe they have and i can't read properly): the stereo jack "trick" for powering on pedals would cause any positive voltage on the ring to short to ground, so you'd need to make sure you only use DIY or modded pedals for this to be practical. unless i'm missing something.

oh... and wouldn't you need to install stereo jacks for every single output? i usually use stereo for everything personally, but not sure everyone does.

[brand0nized]

i'm surprised no-one has mentioned this already (or maybe they have and i can't read properly): the stereo jack "trick" for powering on pedals would cause any positive voltage on the ring to short to ground, so you'd need to make sure you only use DIY or modded pedals for this to be practical. unless i'm missing something.

oh... and wouldn't you need to install stereo jacks for every single output? i usually use stereo for everything personally, but not sure everyone does.

In the context of this forum, I'm guessing, yes, it would have to be for DIY only, unless you mod everything. But OP's original point was to save space inside the enclosure, so it'd be cool for tighter projects.

The best use I can think of is with 1590A pedals since they're so small on the inside, but stereo 1/4" plugs aren't low profile, so in my mind, it is redundant to build small pedals that have smaller footprints if your patch cables are just going to take up the space you've saved.

[midwayfair]

There's a company that does this. They modify amps to supply power to the pedals, and then you have all your pedals carry it (all the pedals have to be modded, but there's a bunch of somewhat well-known pedal builders that do this). I can't remember their name, but they've been at the Amp shows.

I don't remember hearing any noise from them, but that was hardly the quietest environment.

[MrStab]

In the context of this forum

as much as i strive to keep my pedalboard DIY-only, those factory pedals can be sneaky. my point was probably a given, but a consideration nonetheless. if universalism isn't a factor, even to the small degree allowed by unpredicted circumstances, then i guess it's not an issue.

i was reading a thread the other day about the viability of using 3.5mm jacks, and the main argument against it was practicality against the standard (not the standard being perfect), but those were to give away whereas this is for the OP's personal use. perosnal use, officer. i swear. lol

There's a company that does this. They modify amps to supply power to the pedals, and then you have all your pedals carry it (all the pedals have to be modded, but there's a bunch of somewhat well-known pedal builders that do this). I can't remember their name, but they've been at the Amp shows.

i've seen a company that does it with (what seems like) DIN cables. at least, i think they sent DC down the cable. would DIN offer any advantage over TRS here? maybe they use a balanced signal (some protection against ripple, hum etc.?) and have an "interception box" at either end to convert to unbalanced and split the power. i can't remember - i'd need to look it up again. that system's probably not too far out of the ballpark, either.

[Seljer]

If the signal were balanced I think you would safe. In theory, the power noise would be common-mode which lead it to being canceled out when you summed/subtracted the lines from each other.
This of course means an entire extra chunk of balanced-to-unbalanced circuitry or pricey audio transformers at the start and end of every pedal  

[MrStab]

the only way i could ever really justify a one-cable system in my rig at least would be if i were using a lot of stuff in my amp's loop as well as in the front, which i'm not at the moment. but there's definitely an appetite for it, it would seem.

[ashcat_lt]

i'm surprised no-one has mentioned this already (or maybe they have and i can't read properly): the stereo jack "trick" for powering on pedals would cause any positive voltage on the ring to short to ground, so you'd need to make sure you only use DIY or modded pedals for this to be practical. unless i'm missing something.

Take a look at that again.  If you're using TRS<>TRS cables between the pedals, you might have a brief short as you plug in/out, but in normal usage it would work fine.  You would need a jumper in place of the battery and/or power jack.

[MrStab]

Take a look at that again.

ahhh... *kicks self* the input-power on thing relies on just one big sleeve where the otherwise-isolated ring would be. cheers for making me realise!

i'd say i should think before i post, but i tried that and that doesn't work either. lol

[cruisemates]

Guys - it is not impossible t all, I have been using one for two years now. It is called the Fuchs P3 Power station (yes, from the amp company).

It works GREAT (no noise) and you do not need TRS cables throughout - what you have is a breakout box to small DC connector cables just like any DC breakout box. The difference is that the 9v comes down the cable, so the AC plug is at your amp. here is a link:

http://www.fuchsaudiotechnology.com/products-plush-detail.php?id=p3_power_station

The only drawback is you need to be careful not to "hotplug" it. It should be fully connected before you power it up.