A proper head scratcher...

ICBM

Bridgehouse said:

The pickups aren’t connected

Ah! Well it's not those then .

PhilKing

Interesting that there is no ground to the Ghost system (other than the ring short).  I wonder if that has anything to do with it?

This diagram shows a ground with active pickups:

http://www.graphtech.com/docs/default-document-library/powering-active-pickups.pdf?sfvrsn=2

PhilKing

duplicate post due to link

PhilKing

duplicate post due to link

PhilKing

duplicate post due to link

Bridgehouse

ICBM said:

Bridgehouse said:

The pickups aren’t connected

Ah! Well it's not those then .

Nope. Def the ghost Preamp board. I’m going to wrap it in tinfoil later as an experiment

Bridgehouse

PhilKing said:

Interesting that the Ghost isn't grounded.  This diagram shows a ground connection:

http://www.graphtech.com/docs/default-document-library/powering-active-pickups.pdf?sfvrsn=2

It’s grounded - one of the wires from the black ground row goes to my common ground. 

ICBM

Bridgehouse said:

Nope. Def the ghost Preamp board. I’m going to wrap it in tinfoil later as an experiment

Put it in a small plastic bag first to be certain you don't short out anything.

Bridgehouse

ICBM said:

Bridgehouse said:

Nope. Def the ghost Preamp board. I’m going to wrap it in tinfoil later as an experiment

Put it in a small plastic bag first to be certain you don't short out anything.

Andyjr1515

axisus said:

Sorry, two sentences in and my head exploded. 

Well, having put in ghost acoustiphonics in a couple of my LP's - one with an additional piggy-backed hexpander midi module and associated switches, I got all the way to the bottom of the thread.

And THEN my head exploded.

Bridgehouse

Andyjr1515 said:

axisus said:

Sorry, two sentences in and my head exploded. 

Well, having put in ghost acoustiphonics in a couple of my LP's - one with an additional piggy-backed hexpander midi module and associated switches, I got all the way to the bottom of the thread.

And THEN my head exploded.

Wait till I try my experiments later... I suspect there is more explosion to come!!!

Bridgehouse

Update for the disinterested part 1!

Experiment 1 - long leads to the socket:



The socket is a metre from tbe ghost board. No interference at all. The high pitched noise starts faintly at about 25cm away and gets stronger until right next to the ghost board when it’s very loud indeed.


Experiment 2 - cable connection from jack socket, then wireless controller turned on and held in hand - noise from 25cm out to right up to ghost board exactly the same - it has nothing to do with the circuit at all in the slightest etc.. 

Bridgehouse

Experiment No. 3 - Tin Foil placed around ghost board, switch and vol pot...


And it cuts down the noise significantly..... very significantly. 

So shielding is the answer. Sigh. OK. On with the shielding it is then.

Bridgehouse

In terms of how much it cuts down the noise - it becomes a very faint and nearly imperceptible noise at about 6cm away...

ICBM

So definitely airborne then.

If 6cm still isn’t far enough when it’s all back in the bass, try a double layer of foil.

Bridgehouse

ICBM said:

So definitely airborne then.

If 6cm still isn’t far enough when it’s all back in the bass, try a double layer of foil.

Yep - going to experiment with it back in to find the best fit

Bridgehouse

@ICBM - been pondering shield strategy - the cables on the loom are acting as an antenna a bit - should I shield them with braided tinned shielding and does that need to be grounded?

I think I also need to shield the inside part of the jack socket as it’s inside the cavity shield and another unshielded antenna - thoughts?

normula1

You need the universal shield of an Altoids tin

Bridgehouse

normula1 said:

You need the universal shield of an Altoids tin

You’re right! Shame it wouldn’t fit in the control cavity tho

ICBM

Bridgehouse said:

@ICBM - been pondering shield strategy - the cables on the loom are acting as an antenna a bit - should I shield them with braided tinned shielding and does that need to be grounded?

That should work, and yes - shielding always needs to be connected to ground.

Bridgehouse said:

I think I also need to shield the inside part of the jack socket as it’s inside the cavity shield and another unshielded antenna - thoughts?

Probably not, since it will be on the low-impedance output of the preamp. But you could try it.