Is putting at least a steel shield between toroids and a preamp PCB worthwhile? Building an Aikido based line stage and working out the best layout. I can keep all the AC components on one side. Is ~6" from the nearest amplification stage enough, or should I put a steel or mu metal magnetic shield between the power and preamp sides? I may put a phono preamp in the chassis later.
Toroids produce small stray magnetic fields and are comparatively immune to stray magnetic fields.
IMO, that 6 inches rates to be OK.
IMO, that 6 inches rates to be OK.
Maybe he wants to screen the circuit from the mains field from the transformer, not the other way around.
But I agree that toroids have very little stray fields too.
The only point where flux can 'escape', so to say, is where the wiring leaves the core. Best not to point that area directly at your circuit.
Jan
But I agree that toroids have very little stray fields too.
The only point where flux can 'escape', so to say, is where the wiring leaves the core. Best not to point that area directly at your circuit.
Jan
Simple steel does not shield significantly 50Hz magnetic stray fields. Only mu-metal does. I learned this the hard way when I tried to shield the CRT tube of an oscillosscope from the mains transformer stray shield bending steel sheets to just no avail.
All depends on the circuit gains etc involved. If you are getting a custom transformer then spec a GOSS band as it will make a difference in a compact housing. But the biggest gains to be had are by rotating the transformer to find the null point. 8-10 dB and in some cases 2x that.
I hope to post links to some videos later this week showing this.
I hope to post links to some videos later this week showing this.