PSU cap is ok see attached measurement, can be the heater elevated cap?
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![WP_20170315_001[1].jpg](/community/data/attachments/562/562029-56b67d39acec10b69870778f9a97ea43.jpg)
Unlikely but test it. I havent followed all posts here but I think I saw (I might be wrong) fairly long twisted pairs from regs which you may try shorten or capping.
Higher frequency noice is likely oscillation between components (caps, inductors, tubes, wires etc). Salas wondered about woofer movements which is indications of low frequency motorboating oscillations, but you say you hear higher freq artifacts. Oscillations can follow the whole scale from near DC to GHz.
Higher frequency noice is likely oscillation between components (caps, inductors, tubes, wires etc). Salas wondered about woofer movements which is indications of low frequency motorboating oscillations, but you say you hear higher freq artifacts. Oscillations can follow the whole scale from near DC to GHz.
![WP_20170315_003[1].jpg](/community/data/attachments/562/562060-8e10268caaf1f4e8d2f7cd96af93612c.jpg)
![WP_20170315_004[1].jpg](/community/data/attachments/562/562076-b9c5f98c1e2617e36dca9e29a061b4cb.jpg)
The scope line only moves at 10mV/cm and 5mV, time base don't related, moves at all mS sets.
149 mV is from my perspective a very stable rail when we are talking HV.
I read somewhere for preamp 3mV or ripple is OK not using any kind of regulator.
I would say that is a question of which ripple we are talking about. If it was in the audible frequency spectra 20-20000 Hz it would be to much for this application. This is not that kind of ripple that is regulated in a AC to DC filter, this is low frequency rail voltage variation usualy caused by tempdrift in active regulations or in passive filters often by variations in the grid.
That itself would not be causing what you hear when you say high frequency disturbances. It could of course be a secondary symptom of it.
For a solution we must know the problem first. Where is ripple of any frequency on the scope scan? Is there any? AC coupled and moving the flat trace up and down slowly can't be DC because there is a capacitor on the scope's input. Can it be riding on 50HZ hum? No, its not periodic and its not fast enough. Being the same all over the time scale can it be the scope's vertical sync is bit unstable on noise or an old part inside it playing up? Maybe. Tells us nothing secure as an onscreen movement when no woofer movement follows it.
Thanks guys, attached pics of grounding.
Left pic SLB connected to chassis
Left centered pic mains PSU cap ground connect to SLB
Right centered pic signal ground from Itch to SLB
Right pic mains earth coming from PSU chassis connected to Itch chassis
Left pic SLB connected to chassis
Left centered pic mains PSU cap ground connect to SLB
Right centered pic signal ground from Itch to SLB
Right pic mains earth coming from PSU chassis connected to Itch chassis
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At 1x in a tubes circuit the probe can end up in danger. At 10x has its full DC+AC rating. Use 10x where it has its full MHZ also and its more protected.
It can happen to me sometimes on older scopes on AC setting that the scope kind of cant decide if its an AC or DC signal. I guess its when the variations are in the low frequency borderland for the cap to charge and discharge and the trace starts moving up and down.