9 Volt power supply/battery replacement

[kags]

Some info here and lots of good info on the guitar forums.
Post in thread 'DIY isolated power supply for guitar pedal board'
https://groupdiy.com/threads/diy-isolated-power-supply-for-guitar-pedal-board.52107/post-663697

 

[S.Samuelsson]

Hi.

It may make the most sense to chalk this up to being a limited use hack with an approximate 60% chance of usability.

IME, make that ~20% if the device is really designed to be battery only.
And even then, some of the 20% may well fall into "I can't hear it so the noise/hum/interference isn't there" category .
There are very good reasons to design and manufacture effect pedals to be battery only, and usually any of those reasons automatically mean that there's very little or no chance to use that design free from noise or other problems with a wall- or a cord wart.

I'm relatively young, so the battery eating effect pedals were probably even a bigger problem before I got into 'em in ~mid 80's, and there hasn't been a viable solution to that inconvenience as far as I know.
Other than rechargeable battery packs that is.
The problem with battery pack approach is the fact that any relatively modern battery bank has a smps section for multiple reasons, or at least some "smartness", so those can't be used with audio unless designed to.
And then the cost will be relatively high, prohibitive for most of us.

9V rechargeable batteries can't be used, because the chemistry is different with different technologies, and so is the (cell) voltage.

Perhaps some day a breakthrough is made, and we musicians can have reliable, high capacity 9V batteries to power our pedals with, but I for one wouldn't get my hopes up for that to happen.

Regards,
Sam

 

[Wavelength]

All,
I am a pretty good fan of That Pedal Show and I have worked with Dan on isolation a lot and have done really really low noise designs for a number of products that I have built for years.

Pedals are a problem because when powered by a supply you have the power supply ground and the analog ground. The lowest noise will happen when the supply is totally isolated from ground and it inherits the analog ground of the other pedals.
As soon as you parallel pedal power you now have created a ground loop between the pedals which causes a problem.
The other problem is pedals that have positive ground like PNP based fuzz pedals and other transistor designs.
Both JHS and GigRig sell isolated battery supplies. Basically these take 9V in and DCDC convert and isolate the power into a new isolated supply.
I started testing a bunch of commercial supplies some of which have isolated or partly isolated, some DCDC convert each connection making them totally isolated and even the EHX MP10 has a linear transformer with 10 secondaries, 10 bridge rectifiers and 10 separate 9V regulators.

If you have low current pedals (i.e. less than 100ma draw) GigRig makes an isolator that will support 4 pedals. Like I make a couple of amps with 9V supplies on the back. Like the one in the moniker. Take that split it in 2 with a Y cable then plug that into 2 separate isolators and power 8 pedals on my small go to board (fuzz, treble booster, boss TU3, Special Cranker, Thorpy Peackeeper, MXR Flanger, MXR CC, my tube buffer->amp

Some pedals are just designed for batteries. Batter eliminators will work for those.

If you have noise, what frequency is it at will probably determine where the problem exits.

Thanks,
Gordon

 

[Gus]

Have you looked at GEOFEX?

 

[Tubetec]

Some of these so called boutique pedals need a dedicated 2A supply ,
its the digital ones you have to watch out for ,

A pedal board is a rats nest of contaminated ground loops ,
not everything runs at 9V anymore either .

Not to mention the typical airbourne RF single coil pickup are famous for ,
it all amounts to a load of unwanted garbage superimposed on your signal ,

Did you ever look a guitarist in the eye and tell him ,
'were going to have to loose the pedal board ' , now what pedals do you actually need on this tune , lets get rid of the rest .
If you do it diplomatically hopefully the fragile eggshell ego doesnt crack

 

[Tubetec]

Why anyone would want to put a digital piece of crap between the guitar pickup and the tube amp is beyond me ........

 

[Wavelength]

Why anyone would want to put a digital piece of crap between the guitar pickup and the tube amp is beyond me ........

Have to agree with you! I have several and they just don't make it. I think the big problem is getting the most out of the bits you have there. You have to have a really nice compander or autoleveler to get good results. Plus good ESS and AKM AD/DA chips are not cheap.

 

[Newmarket]

Hi.



IME, make that ~20% if the device is really designed to be battery only.
And even then, some of the 20% may well fall into "I can't hear it so the noise/hum/interference isn't there" category .
There are very good reasons to design and manufacture effect pedals to be battery only, and usually any of those reasons automatically mean that there's very little or no chance to use that design free from noise or other problems with a wall- or a cord wart.

Use a well regulated and galvanically isolated DC feed (with sufficient current capability of course) and you'll be fine .

I'm relatively young, so the battery eating effect pedals were probably even a bigger problem before I got into 'em in ~mid 80's, and there hasn't been a viable solution to that inconvenience as far as I know.
Other than rechargeable battery packs that is.
The problem with battery pack approach is the fact that any relatively modern battery bank has a smps section for multiple reasons, or at least some "smartness", so those can't be used with audio unless designed to.
And then the cost will be relatively high, prohibitive for most of us.

9V rechargeable batteries can't be used, because the chemistry is different with different technologies, and so is the (cell) voltage.

Normal NiMH rechargeable PP3 can be reliably used in pedals. The slightly lower cell voltage is compensated to some extent by a lower internal impedance (so def don't test them with your tongue ).
You will get a different response if you're relying on some "sag" effect. But that also goes for different non-rechargeable battery chemistries.