Good coils are expensive! For line filters, I use vacuum-melted nanocrystalline coils with high permeability and very low Ri (internal resistance). The filtering effect of such coils is very consistent up to well over 100 kHz.
An isolation transformer, especially an EI-core isolation transformer, is a very effective component to use in a series cascade of EMI filters. Big, heavy, expensive, and effective.
Switch to DC heaters also because of wind/solar caused mains fluctuations. Give that tube pre a good regulated PSU. Despite all the often irrational objections of tube people against "sand" there is no other way anymore. The days of purely ohmic grid load are long gone, it is inverter heaven today. So it will be mains filtering, DC/regulated conversion and input filtering (against BT, Wireless, DECT, cell phone etc.) if one desires silence, possibly even SMPS for PSU in the near future.
BTW this post was typed with sand.
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Ideally it would be a RF,EMI filter, followed with DC blocker (diodes and caps) + Variac + regulator to stabilize the AC
My SS is not affected, because the PS is class D and regulated and outside the amp, but a traditional diode, transformer etc especially the tube heaters suffer so much on certain days, I will have no choice to use a variac and a DC blocker, RFI filter combo.
Oh yes you do. Many transformer based PSUs will need replacement for SMPS with the current state/quality of mains voltage. Besides their many features a positive one is that these tolerate mains voltage fluctuations like a champ.
BTW you have a class D PSU!?
BTW you have a class D PSU!?
For the solid state amp , sorry switching, as class d is a switching amp,
It is regulated 1%, 0.1 v DC maximum
It is regulated 1%, 0.1 v DC maximum
Chinese variation of 20 amps are cheap, so i could get one for the power amp and a small one 5 amps for the computer, dac, pre amp, phone,
I would have to first build a ac coupling with caps and power diodes, and before some rfi filter,
I could dial the proper ideal voltage for my amp and forget about bias and other inconveniences
It is in late night that the noise increases,
It is Saturday that the transformer buzz too much
I would have to first build a ac coupling with caps and power diodes, and before some rfi filter,
I could dial the proper ideal voltage for my amp and forget about bias and other inconveniences
It is in late night that the noise increases,
It is Saturday that the transformer buzz too much
The advantage of the variac is that I will never turn off the equipment again, I will idle it at 20% so there is always some electron flow and caps never depolarize.