Bypass bleeding

[edo1123]

Okay, I've recently started boxing my pedals and I found basically every pedal I've boxed has the same issue: a whine noise in bypass.

I used 3pdt stomp and the true bypass wiring form tagboard. What is actually bugging me is that if I use my Atk 200 I have no noise in bypass as soon as I switch to guitar I get this unstoppable noise. I thought it was something in my builds, but I have the same problem with an original cry baby. I've tried with two power supply, but it made no difference at all.

Is it something with my guitars or with my bass? Is something I can get rid of or I have to live with this haunting presence for the rest of my life?

[Neil mcNasty]

The first thing that comes to mind, is the fact that your Atk 200 has active pickups, and your guitars has not...
Also the fact that (from what I understand) you only have this problem when all pedals are bypassed, and not when there is a pedal that is on.
This indicates that there is DC current bleeding trough to (or from) the amp in some way.

Are both the power supplies from T-Rex?
If so that could explain a lot... Those are horrible!
Here is a discussion and a circuit that often help to smooth out ripples in the current from bad power supplies:
http://guitar-fx-layouts.42897.x6.nabble.com/Weird-quot-hum-quot-from-a-couple-of-pedals-td20501.html;cid=1474053970962-847#a20590

Also... have you tried them with a different amp?

Here's what I would do:
- Unplug/remove all the pedals and try them one at the time.
Also make sure you disconnect all the other pedals from the power supply as well, when testing them.
Is it still happening (with all of them)?
If it only happens with one of them, you have found the culprit!
If one pedal does not have a proper power-filter (or if you have a bad Electrolytic cap) it can create high pitched noise, specially in high gain circuits.
This is often only noticeable when the pedal is off, since the input/output cap of an active pedal blocks DC from bleeding trough to the amp.

- Check your internal pedal wiring and make sure that any power leads are as far away from the audio signal leads/cables as possible. Also check all ground leads and make sure that they are all good.

- Check all your patch cables and your jacks for weak ground connections.
One single bad cable can introduce a lot of issues, and is often something people forget to check.
Specially if you make your own patch cables. The life span of a home made cable is very often very short compared to factory made cables.
Personally I never make my own patch cables, since that has been my biggest problem when it comes to noise and bad connections.

- Build and try this little handy tool: http://guitar-fx-layouts.42897.x6.nabble.com/Lehle-DC-Filter-td24719.html#a30329
It blocks DC current from the audio path, and should be placed last in your pedal chain, before going to the amp.

Whatever you do... Make sure that you systematically check your gear, attacking the problem with one test and one unit at the time, instead of jumping around trying a lot of different stuff.

Hope this helps you finding the problem...

[Beaker]

Good tips from Neil.

There is a whole bunch of possible causes of noise like this, and it's not always straightforward tracking down the source.

Nevever assume that any link in the chain is good. Always test every thing - every pedal and every lead individually first, then add combinations of pedals and leads until you find the culprit. You have not said whether you are having problems when using one pedal, or if you have a whole string of pedals hooked up together.

You have not said whether the power supplies are the same, or two different brands, so bear this in mind as well. If they are the same brand, and they are unregulated, this could be your issue.

As Neil said, work methodically. Get back to us if us with a progress report, and we'll see what you need to do to rectify things.

[edo1123]

Thanks guys. It took me some time to check all the potential culprit. I've tried my builds and the cry baby, one by one, with my amp and with a mxr microamp I use to practice (it's almost noiseless), but nothing seems to explain the noise. It appears when I plug the supply, which is a 1spot, and disappear as soon as I unplug it.

I have to try the huminetor and the filter, even though I didn't get where to put it.

All the wiring seems pretty solid and since I have the same issue with a pedal built by Jim Dunlop, maybe it's not in the builds.

[Neil mcNasty]

You have found your culprit!
It's your power supply!

The Huminator goes between your power supply and the pedals.

This is what i do when using a 1spot power supply:
I have/build a Huminator based filtering box that has one input, and several outputs.
The input has the two diodes and a large filter cap (half wave rectification/extra ripple smoothing).
And each output has it's own 47-100R resistor and a 47uf filter cap that isolates every pedal from each other. This is called "power decoupling" and is almost always skipped, even in expensive pedal power supplies in order to cut down on parts/costs.

Look at my layout in the Huminator post (the one with the schematic included).
It has both a single Huminator, and a quad version for decoupling 4 power outputs.
This layout can easily be expanded with more decoupled outputs.

I use these instead of the normal daisy chain and has never come across any noise issues after i started using it instead of a daisy chain.

The only drawback when using this is that it drops the voltage a tiny bit.
So when you got pedals that draw larger amounts of current (more than 100mA), then the voltage will drop a bit more than with a pedal that has a low current draw, and can affect the circuit a bit ( but has only happened with one of my pedals that draws about 300mA)

[edo1123]

Okay, Could I build one huminator and then daisy changing? And why with the Atk this is not happening?

[Beaker]

The ATK is an active bass, the onboard buffer/preamp is helping prevent the whine.

The One Spot is a really popular power supply, and for most people, most of the time they cause no problems at all. However this is a known issue with them - they just don't want to play nicely with some pedals.

I think you can use one hum eliminator and a daisy chain, but as Neil says it should work much better with a multi eliminator and pig tails for each pedal, as it isolates each pedal from the rest.
I've never built one though so don't know for sure.

[Neil mcNasty]

Very important regarding using just a single Huminator betwween the power supply and your daisy-chain:
The resistor in the Huminator circuit lowers the voltage just a tiny bit when using it with one pedal that draws low current (like 10mA). Then the voltage drop is not noticeable...
But when you draw lager amounts of current (like when powering 8 pedals that together draws 2-300mA, (or more), the voltage drop can become quite large, and you might loose several volts in the worst case scenarios.
Meaning: the higher the mA current that is drawn via the Huminator, the larger the voltage drop you will get!

This is the reason that I build Huminator boxes that has one input for the One-Spot and has several decoupled/Huminator outputs, so that it filters the power for each pedal by itself, instead of the daisy-chain as a whole...
You can of course try to put it between the One-Spot and the daisy-chain. But as soon as you put a Delay or Reverb pedal in the chain (which normally draw about 100mA or more), you will get quite a significant voltage drop.
Also:
Using it this way might defeat the purpose of the Huminator entirely, since it is a circuit that is design to create separation/filtering between pedals, or to isolate a single troublesome pedal, so that it does not affect the other pedals.

[edo1123]

Okay. And if I put a single huminator in each pedal? Should this  prevent the noise and keep the amperage the same?

[Neil mcNasty]

Yes!
I often use those tiny 1590LB boxes where I can get one input on one side of it and then outputs one each of the other sides with a LED indicator on top (so that I can tell that it is getting power)
Or you can use small plastic boxes that don't cost as much, since the need for a grounded box does not apply to these instances, like it does with audio circuits.
I then wire them point-to-point, and then i fill them with hot glue so that I'm sure nothing is able move anywhere an create a short circuit.

If you give me a second or two, I'll draw up something that show how I've done it...

... a couple of minutes later:
This how I've done it, but you can add as many outputs as you need.
This is just to show how simple it can be done...
(forgot to add an LED indicator on this)

[edo1123]

Thanks, man. This thing is driving me crazy, mostly because I can't get a clean signal, but I have just some super heavy distortion and fuzz..

[Neil mcNasty]

Yeah! I know what you mean... Been there!
But after building a couple of these, I have never had that problem again.

This is a great way to cut costs and be able to use much cheaper solutions/one-spots than the "so called" professional power supplies that cost a shitload, and does not even have proper decoupling between the outputs.
I highly recommend the Boss One-Spots instead of the ones you find at the electronic stores.
Those are dirt cheap and can handle 600mA, and are quite noise free with a normal daisy chain.
The ones I find at the electronic stores are often extremely noisy.
In fact, some of them are so noisy that even these Huminator boxes can not remove the noise.

Another cool option could be to use a Laptop Power Supply feeding into a couple of 7809 Voltage Regulators (they can handle up to 1amp) and then have Huminators/decoupling after that.
Those power supplies normally have quite good power filtering, since computers are very sensitive to stuff like that...

Maybe it's time to put our heads together an come up with a "poor mans power supply/filtering box" that enables us to cut some corners regarding costs, based on Laptop Power Supplies?
The though has been in my head for a while now, and the beauty is; that they put out 19.5 volt, and often up to 4-5 amps.
So it should be possible to get both 9v, 12v and 18v out of such a system...
I'm quite sure it should be possible to come up with a very low cost solution that can compete with the  professional power supplies, with some experimentation...

[edo1123]

Neil, this project could save a lot of money.  !! If I had more skills I'd be glad to work on something like that. Yesteray I saw a computer power supply and saw it was 4,74 A / 19,5 V.. The only "problem" was the polarity (center positive, but for 16€ would be perfect..

[Neil mcNasty]

The Center Positive issue can be dealt with easily if the instructions are clear enough with a big "WARNING! Input is Center Positive, make sure to wire accordingly" notice.
If the polarity protection is good enough it should be safe, so that it does not fry someone is wiring it the wrong way. I think by using transistors for this might be a better way than the regular diode way, as far as I know...
The input power Jack also a bit different if I remember correctly, so it should be able to make it so that it is impossible to plug in the wrong plug.

I'll start a new thread here on the subject and see how the response is...

[edo1123]

Neil, another question. Since I'm planning to build a bunch of pedal for my pedalboard, can I build a single huminator in each box? It's actually cheaper than build a single box with several outputs. And (maybe) the last question, I saw your thread in open chat and I was wondering: how is going the "definitive power supply" construction?