WHA WHA NOISE- HELP

[Rhandy]

Hello

Someone can help me.

I buy one used zakkwylde ZW95 wha pedal.

In first wha doesnt sound good. I open to see it inside and meter with multimeter the pontentiometer. And I see is not well calibrated because when wheel is close I read 105k ohm, and when full open I have 15k.

I adjust Wheel And now I have 105k close, and 66ohm open.

The problem is when is full open it makes lots of hiss. Is Like you have pre amplifier and capture some noises, like antenna.

ANY SUGGESTION?

[GibsonGM]

Hi Rhandy,

I don't think adjusting the pot on the treadle is going to remove hiss...that is just for setting the maximum high point of the sweep (and of course, the low by default).     The more you adjust to the high end, the noisier it's going to be (hiss).    It's usually not something done with a meter...most people just use their ears, and adjust a little at a time, and try the wah out.

If you DO have a tone you like, and as you say, the hissing is bothering you, there are a couple of tricks that can be done.
You would have to post the schematic of the wah, and we'll show you some things that may help a little.  But keep in mind, it probably will not be made perfectly quiet.

One thing is to use shielded cable for your inputs and outputs, with one end grounded...and being cautious about where you run signal wires...

See if you can post the schematic...and maybe  a picture of the inside of your pedal! 

[Rhandy]

Hi

I dont heve specific shematic of ZW-45.

The real thing is inside have pcb board of GCB-95. Some people said with , dunlop make little mods for have more vocal response.

There are lots of shematics for gcb-95 but i dont found any one for zw45.

here my pictures. https://www.dropbox.com/sh/jwpt0kajb1f0ehh/AABjV6fLXJComA-_3aBv9sCpa?dl=0

Other thing I use instrument cable I  Plug guitar tp BOSS TU3 ->WHA->Chorus Tc electronic dreamtheater - > AMP  -> FXLOOP - > CARBON COPY - > BOSS RV6

see here https://www.dropbox.com/s/d7tia5rnlw8xq9d/2016-02-21%2016.51.40.jpg?dl=0

How I can ground cable???

[GibsonGM]

Ok, Rhandy...there are a couple of ways to proceed here.  First, I think your cable is already grounded!  If not, it would go "BZZZZZZZZ"      

1)   If you use ONLY the wah, and have distortion on your amp - does it still make bad hiss?  Use a battery when you do this...better?   It COULD be amplifying the noise from something else.  If you take a pencil eraser and push lightly on the board, and on the jacks...does anything happen (be gentle).   If something is loose, this might help you find it.  You are SURE they are instrument cables, and not speaker cables, right? (ha ha, had to ask).

2)  Yes, there could be something wrong inside the wah...a bad capacitor could make hiss.   The GCB-95 does not look that complicated.   So I would then make an audio probe and try to find where the noise begins, after eliminating anything loose inside the wah.    Use a search engine to get the schematic, and follow that from input to output.   

[Rhandy]

Hi GibsonGM

First I make your test. I discover one thing, I dont have one wha pedal, I have one "Radio"!  Yes!! I can Listen radio on my guitar cab.

Put volume louder and see my vídeos

I found shematic  https://www.dropbox.com/s/xzx10z72bc7h2f3/Dunlop_WyldeWah_ZW45.PDF?dl=0

[GibsonGM]

Ha ha, now you can listen to the radio, too!!      If you put the back cover on, does it still do this?

The amount of hiss in pedal-forward would not bother me....but, is the "mmmmmmmmmmmmm" noise something that is always there?  That is a lower frequency, and is not hum.  That is a sign of poor power supply filtering, or a nearby flourescent light, something like that, creating noise.  If you are near lighting or something, try moving your stuff away (or turn the light off) and see if you can make that humm go away.  Put back cover on for this.


As for the noises, the clicking when you tap...I personally would pull the PCB and re-flow the solder in the input jack.  Might as well do the output jack, too.  A bad solder joint could cause that clicking, and maybe the radio too (ok, that's reaching but...).         

Check that the 22pF cap is in the circuit, and soldered ok. That should shunt RF.  Look at all the solder connections in the input stage.  If the radio thing continues (with the back on...), I would place a 68pF cap across my input jack terminals.   It should not affect any frequencies that you can hear (you won't know it's there).  Thing is, that's to fix something that should be happening - better to find out why.

[Rhandy]

Hi!!!

My room light is Led light!

But I found some stranges more noises, before I resolder pcb board.

The shematic is wrong,doesnt have all componentes. Check r14 doesnt exist on shematic. see here. https://www.dropbox.com/s/4r6bnq8ppzhq657/2016-02-21%2016.34.20.jpg?dl=0

Please see my vídeos.

[GibsonGM]

Ok, Rhandy!     I think you have other problems besides the wah making a "hiss", ha ha.

That sounds to me like 60Hz hum.    That means (yes) there is a bad ground somewhere...a bad capacitor in a power supply...or something is coupling into your audio path.  Usually, if it's a light or motor or something, it's easy to find.  I will assume you checked the area, and there's nothing like that?

The high hiss of the wah doesn't concern me...mine have all done that on the treble sweep.  The buzz does, however.

How does your guitar sound plugged directly to the amp? Turn up the gain on it, still ok?   How about with just 1 pedal?  How about if it's only used on batteries?    Then 2 pedals....then add the wah last.  Try different cords.    Then, if all's ok, try the effects loop with 1 effect...you see, process of elimination.

Try to find out what is causing that hum!   A bad ground on your GUITAR will certainly do that.  Or a problem with a cord.   That reminds me of a not-quite-plugged in cord...bad jack??   And yes, it can be inside one of your pedals, or the amp. 

It seems like a lot to have to look at, but it's really not...you have to be the detective    

Edit:  PS - if it IS only the wah doing this...re-flow the jacks' solder, and make sure there is a clean, solid ground connection to the enclosure!  Often done at a jack.  Check that ribbon connector, too!  Wiggle it.   If it's the wah, something is loose, a PCB trace may be broken, or a bad solder joint....

[Rhandy]

Ok, GibsonGm!

When I plug my guitar direct to Engl Amp, I don´t have any noise on clean channel, On distortion channel I have one litle noise, but I think is normal on distortion you can see it here, before I push wha button.

And About wha! I read this:

This from Dunlop:

"This is a common occurrence because the inductor in the Wah pedal acts as an antenna. When you are in an area with a lot of radio frequency, the pedal can and will pick up radio stations. It is not very easy to troubleshoot and fix, because it differs so greatly due to the different signals and the varying surroundings. What may work in one region might not work in another.

Check the inductor. If you have a metal inductor, you can purchase a shield from us and place it over the inductor with a ground wire that is placed under one of the screws on the PC Board. This acts as both an AC Hum and RF shield. (It is part number ECB99 - and lists for $12.00) If this doesn't work then...

Wrap the entire black wire harness in Mumetal foil, which comes in a tape format, and hope that that works.

Getting radio stations on your wah pedal is unfortunately, the nature of the beast, and has been that way since its inception. In some areas it is worse than others. It is especially bad in the great lakes region because the lakes act as large antennas sending out the radio signals to all areas - and all wah pedals."

These are just a couple of solutions.

I also try make TRUE BY PASS MOD.

No my wha is true bypass, but radio station doest go away.

The diference between GBC95 and ZW45 are: zw45 have Red Fasel and C5 capacitor is 0.22uf instead of traditional 0.01uf.

I buy new capacitors but I not replace anyone yet.

I have for C1, C5 and C6.




I read this too:

If you've converted to true bypass, replace the 68K series input resistor with a lower value, say 47K. This gives a slight increase in volume. Too low a value is likely to result in the pedal picking up radio interference. This can be addressed by adding small value (10 - 20pF) capacitors between the collector and base of each transistor

Maybe I try put this capacitors?

[GibsonGM]

Hi Rhandy,

I think that LOW humming is really your problem.  It gets worse when you push on the input jack, so I believe you should look at the traces there, and re-flow the solder connections.   The increase in volume of noise when you turn the wah on, is just because the wah is amplifying noise already there.

I wonder if your true bypass mod isn't quite right or something (?)   RF should NOT be audible if that is really true bypass.  Caps will not get rid of that low humming; finding the open ground or place it's "getting in" will.

Do you have the LOW hum with just your guitar plugged into the amp, no wah in the chain?

[Rhandy]

Hi GibsonGm!

When pedal is in truebypass is very quite! the radio only can be listen with wha on and full open.

I resolder input and output jacks!

Today I will test with diferent cables.

Do you have the LOW hum with just your guitar plugged into the amp, no wah in the chain?

Answer your question, Yes I have Low hum.

I Dont know how to cut it! when I use my PODHD500x, I put one Noise Gate. But now I´m not using podhd500x with amp. Pod is only for badroom play.

[GibsonGM]

The low humming suggests a problem with your guitar, or your amp....bad ground on guitar or a cable,  OR  either there is a ground not connected inside the amp, or one that is faulty....bad input jack on the amp would do this....OR, lastly, the power supply filter caps are bad. 

Try another guitar with the amp, and a new cable that you KNOW is good.  If it still has 60Hz hum, plug amp into different line power circuit. Test again.  If the amp has a cord to the speaker cab, be SURE it is a speaker cable!!  If not, it WILL hum that way.

One last thing that could make that low hum is SOMETHING nearby that is getting into your line power, as we discussed earlier.  That isn't too likely, as you said you've gone around and checked this out.  Feel free to go around the house again to see, though, as this is easier than fixing things!   

Personally, I would worry about that hum before the wah.  It may mean your amp is malfunctioning, and it COULD get damaged if it is filter caps. 
But yes, if all is good and the wah picks up radio, the bypass caps on the transistors are certainly an option!  You will not hear this, the frequencies they affect are above those we can hear.  They will shunt RF out of the audio path.  I am surprised it is doing that, though...but sometimes it happens.

[Rhandy]

Hi GibsonGm!

In first I make on ground test to my line.

Could see it here

I try change all cables but hum still there when I use distortion.

Cable connection to cab is SPEAKER CABLE WITH NEUTRICK PLUGS.




I will try in other amp.

Thank you.

[GibsonGM]

You are on the right track, Rhandy.  I don't think you can find trouble on your power lines that way - they function normally but noise is coupled to them, which you cannot read on a meter - you find it by turning other items off...really, we need to be sure your guitar cables are ok.   But now we know your home power is ok.

You are correct - try another amp, use your cords and guitar.  Eliminate them as the source for the hum.  Then we go back to this amp. 

Is your amp a tube amp?  A tube that is going bad may also sound this way.  But first, we need to know all cords, guitars and jacks are ok.    Move things around, including your volume and tone pots.  If there is something loose, we need to know this before you do anything involving opening your amp  

I once had a Stratocaster that made that hum.  The ground wire to the bridge had come disconnected...

[Rhandy]

Hi GibsonGM!


In first My Amp is Tube Amp



I start to unplug all cables to Amp.


I put on distortion channel And put Master to on 10. With nothing pluged to Amp, I still have hum and RF, not very acentuated, but I can listen a litle.

I create my earth loop ground eliminator.

Two paralell diodes in ground line.

But humm and Rf doesnt go Away.

I try put one ferrite filter on Ac cable, but doesnt work!





Today I have one answer from Engl Technik.

Hi Nuno,

I suppose, that the first preamp tube is highly microphonic. Please try swaping V1 and V2 and report, if anything changes.

Best regards

I have to try it!

One more answer to you. My Guitar is one Gibson Les Paul Standard.

Regards.

[GibsonGM]

Ok, the tech is correct...go ahead and swap the tubes!   Sometimes you can tell if a tube is microphonic by gently tapping it with the eraser end of a pencil.  But for this, just go ahead and swap them and see what happens!     Radio signals CAN be a sign of microphonics. 

Of course the amp must be off, unplugged, and be careful not to touch any circuit components  

[Rhandy]

Ok i swap preamp tubes. Some make more noise other make little less.

But i think all 3 I test are microphonic.

See it here.

My master volume is all open. Nothing is pluged to amp

[GibsonGM]

That doesn't seem too bad, Rhandy...usually microphonic tubes sound sort of like an odd harp if you tap them!  I do not think the preamp tubes are the problem.     

The power tubes look very strange in the video...I will assume they glow steadily and are not red-plating?

I would not be surprised to find that you have a loose jack on the PCB inside.  I have not seen a schematic of your amp, and do not know how the input jack is arranged...how old is the amp?

It is definitely making a hum.  Before going deeper, I would take it to a friend's house and plug in, see if it does this.  I just don't want you to have to open it up if you are not comfortable, or to pay a technician if you don't need to...the art here is to aggravate the problem without the need to take the amp apart very much!

[Rhandy]

Hi GibsonGm!

This amp only have 6 months on my hands. But I know is been maybe 2 or 3 years on the store.

I know I have some blue glow inside power tubes. But Some Engl tecknic says blue glow is normal.

You cant see red because tubes cover.

But I think I have to replace power tubes.

I have Amp shematic. see it here https://www.dropbox.com/s/s6qb8y9pytf9914/e650-ii-schematic%20%281%29.pdf?dl=0

Other thing red leds affect color. But you have reason, when I see video I dont think on Power Tubes and I think pulsate is camera, Like you record one "Old" Tv screen.

Regards

[GibsonGM]

Blue glow is called "fluoresence", and yes, is ok.   

Why do you suspect your power tubes?   Unless something happened to them, they should last for years. 

What is your background with working on amps, Rhandy?  This could be a loose jack or ground connection, 1 or more capacitors in the power supply, or output transformer.   It may be a better idea to take it in and let a tech look at it.   

If I were going to go at this myself, I would have to remove the amp from its enclosure, and look at everything.  Then move things around with a non-conducting wooden dowel...then a little bit of audio probing, perhaps look at some voltage readings here and there.   Look at the power supply with a scope.   All of this must be done with power on, which can kill you VERY easily!   Capacitors can stay energized long after you pull the plug, too...

I believe it is one of the above things, and will not be hard to find the problem or very expensive, but if you haven't gone into a tube amp, it could be bad for you or the amp... if you want to try new power tubes, yes go ahead, that is ok - I believe every amp should have a spare set of tubes anyway!  But they do cost some money.   I wouldn't say that is a 'good way to troubleshoot', but in this case - to have the spares, yes.
Just make sure you get the right ones, ha ha.

Come back if you change tubes, tell us if it works!   PS - you might want to take the diodes off the ground line...