A proper head scratcher...

SteveRobinson

Bridgehouse said:

On my board Tip is blue and Ring is red - 



Because it’s a TRS jack, I’m following this graphtech wiring diagram - 
http://www.graphtech.com/docs/default-document-library/trs-jack.pdf?sfvrsn=2

Yes that should work, no need for a fancy jack with that. You will though require a separate earth to the main earth of the circuit. 

Did you check that the solder tags on the jack are correct, tip and ring?

Bridgehouse

SteveRobinson said:

Bridgehouse said:

On my board Tip is blue and Ring is red - 



Because it’s a TRS jack, I’m following this graphtech wiring diagram - 
http://www.graphtech.com/docs/default-document-library/trs-jack.pdf?sfvrsn=2

Yes that should work, no need for a fancy jack with that.

Did you check that the solder tags on the jack are correct, tip and ring?

I physically attached the tip wire to the tip of the actual jack on the boss wireless and the ground/battery to sleeve and still get the noise - so even without a socket at all!!!

SteveRobinson

Connect the body of the jack to the main circuit earth and try that

Bridgehouse

SteveRobinson said:

Connect the body of the jack to the main circuit earth and try that

Which bit of the body? (not sure what you mean by the body!)

prowla

Bridgehouse said:

prowla said:

Why not just make up an extra interface box, like the one with Variax guitars, to convert the one to the other.

Do you mean external to the bass?

Yep - I've just bought a Variax and it has a pedal which can run power to the guitar via TRS.

An alternative could be to put a mini mixer in-between.

Bridgehouse

prowla said:

Bridgehouse said:

prowla said:

Why not just make up an extra interface box, like the one with Variax guitars, to convert the one to the other.

Do you mean external to the bass?

Yep - I've just bought a Variax and it has a pedal which can run power to the guitar via TRS.

An alternative could be to put a mini mixer in-between.

Kinda defeats the purpose of having a small bug wireless that runs on battery for both tx and rx to connect direct from bass to amp tho

SteveRobinson

Bridgehouse said:

SteveRobinson said:

Connect the body of the jack to the main circuit earth and try that

Which bit of the body? (not sure what you mean by the body!)

You've connected the "ring" wire to the body of the jack (via the earth tag) but not connected this to the circuit earth. I think this is the problem.

Run another wire from the earth tag on the jack to an earth in the circuit such as the back of the mag vol pot. Looking again you should probably run an earth to the back of each pot in the circuit.

ICBM

Bridgehouse said:

@ICBM - given connecting battery and ground to the sleeve and tip to tip still resulted in noise - would the 4 prong jack isolate the battery sufficiently for it to work?

No. It's exactly the same functionally, just that it allows the battery to disconnect when the plug is out.

It sounds like it's just a basic interference problem between the Boss and the preamp, nothing to do with the power after all.

Bridgehouse

SteveRobinson said:

Bridgehouse said:

SteveRobinson said:

Connect the body of the jack to the main circuit earth and try that

Which bit of the body? (not sure what you mean by the body!)

You've connected the "ring" wire to the body of the jack (via the earth tag) but not connected this to the circuit earth. I think this is the problem.

Run another wire from the earth tag on the jack to an earth in the circuit such as the back of the mag vol pot. Looking again you should probably run an earth to the back of each pot in the circuit.

Ah I see what you mean now - I have a wire from the earth tag going to the common ground on the graphtech board, so it’s grounded. 

ICBM

If the jack wasn't grounded it wouldn't work at all, so I don't think that can be it.

Bridgehouse

ICBM said:

Bridgehouse said:

@ICBM - given connecting battery and ground to the sleeve and tip to tip still resulted in noise - would the 4 prong jack isolate the battery sufficiently for it to work?

No. It's exactly the same functionally, just that it allows the battery to disconnect when the plug is out.

It sounds like it's just a basic interference problem between the Boss and the preamp, nothing to do with the power after all.

This is also a strong possibility - if I hold the boss system in my hand when connected, the noise goes away. 

I guess the ultimate question is if there is a way of shielding the graphtech board from the interference. I can’t get the unit physically far enough away from the boss to actually test it though 

ICBM

Bridgehouse said:

This is also a strong possibility - if I hold the boss system in my hand when connected, the noise goes away. 

I guess the ultimate question is if there is a way of shielding the graphtech board from the interference. I can’t get the unit physically far enough away from the boss to actually test it though 

Is that the case if you're not touching any metalwork on the Boss unit or on the bass? Or does it only shield it if you are also touching something grounded?

The noise could be 'airborne' (it's not actually conducted by air, but you know what I mean...) or via the signal connection. If it's the former I would expect it to change depending on whether you're touching metal and hence a shielding issue; if it's the latter it won't and then even getting a TRS extension cable won't help.

Bridgehouse

I’m away from it now, but from memory it doesn’t matter if I’m touching metalwork or not - which does suggest the latter as you stated. 

Bridgehouse

I’m on the verge of giving up tbh. I can’t see a way of removing the high pitched hum at all - I’ve pretty much tried every wiring combo and even with just the ghost board and the output (switch and volume removed) I still get the noise. 

The fact it goes if I hold the Boss unit is maddening - it seems it just doesn’t want to work in this config

ICBM

If it makes you feel any better, solving this sort of issue is one of the worst time and money eaters at the shop. Usually it's someone who wants a sustainer, piezo pickup and onboard preamp all from different manufacturers, and when you finally do get it all working more or less OK after far more time and effort than you can really charge for and it goes back to the customer, they then come back and complain because it's noisy when they use it with their Whammy pedal or something... total nightmare.

I know there are valid musical applications for all this sort of stuff, but usually it makes me want to just set fire to the whole thing.

Bridgehouse

ICBM said:

If it makes you feel any better, solving this sort of issue is one of the worst time and money eaters at the shop. Usually it's someone who wants a sustainer, piezo pickup and onboard preamp all from different manufacturers, and when you finally do get it all working more or less OK after far more time and effort than you can really charge for and it goes back to the customer, they then come back and complain because it's noisy when they use it with their Whammy pedal or something... total nightmare.

I know there are valid musical applications for all this sort of stuff, but usually it makes me want to just set fire to the whole thing.

Thing is, the piezo system on its own isn’t complex - it’s 4 saddles with piezo elements and a Preamp board. That’s it. And that’s all I’m connecting to the boss. 1 Preamp And one output. No mixed other stuff. 

Its just really odd that the boss is picking up interference of some description from the ghost board or visa versa. 

It really sbould just work given I’ve reduced it to the simplest components. 

ICBM

Bridgehouse said:

Thing is, the piezo system on its own isn’t complex - it’s 4 saddles with piezo elements and a Preamp board. That’s it. And that’s all I’m connecting to the boss. 1 Preamp And one output. No mixed other stuff. 

Its just really odd that the boss is picking up interference of some description from the ghost board or visa versa. 

It really sbould just work given I’ve reduced it to the simplest components. 

My guess is that it's high-frequency interference from the radio unit breaking through into the extremely high impedance piezo pickup preamp.

Bridgehouse

ICBM said:

Bridgehouse said:

Thing is, the piezo system on its own isn’t complex - it’s 4 saddles with piezo elements and a Preamp board. That’s it. And that’s all I’m connecting to the boss. 1 Preamp And one output. No mixed other stuff. 

Its just really odd that the boss is picking up interference of some description from the ghost board or visa versa. 

It really sbould just work given I’ve reduced it to the simplest components. 

My guess is that it's high-frequency interference from the radio unit breaking through into the extremely high impedance piezo pickup preamp.

I think you are spot on sir. I will try an experiment later after band rehearsal and jury rig a cable to place the wireless unit well away from it and see what happens.

Is there any way I could shield the ghost board to stop it picking up the high freq interference?

ICBM

Bridgehouse said:

Is there any way I could shield the ghost board to stop it picking up the high freq interference?

It might not be at the board where it's getting in - it could be at the pickups themselves.

If you've shielded the cavity thoroughly then the preamp is shielded already.

Bridgehouse

ICBM said:

Bridgehouse said:

Is there any way I could shield the ghost board to stop it picking up the high freq interference?

It might not be at the board where it's getting in - it could be at the pickups themselves.

If you've shielded the cavity thoroughly then the preamp is shielded already.

The pickups aren’t connected