[Folsom]

I get a lot of RF, not because of the Bugle but where I live. But without playing music it's hard to tell how quiet it should be because of it, I get some hum and static. I'm running a power supply for it, and not batteries.

[doorman]

Mine is battery powered. It's silent.

[Folsom]

I wonder if my Ldr resistors on the input are not performing the role they are suppose to?

[hagtech]

If you have RF, try moving around the input phono cables.  You may hear changes in tuning.  Moving things around could lead to the area of susceptibility.  Perhaps even placing your hand on the unit could change things. 

jh

[Folsom]

I'll play with that. I made the signal ground connect with one wire to Bugle, that goes to both RCA channels. All RCA jacks are on the same ground wire (input and output). The power ground only has one wire from PSU. So I feel like I've reduced most possibilities for noise otherwise. I even isolated the ground from turntable from the case. The case is attached to bugle ground via 150ohm resistance and .1uf cap parrellel. Not sure what else would help.

But this is kinda interesting. Power off or on the Bugle/PSU makes that hum at loud volumes, but it I unhook the power for it then it goes away even if it was off. I guess it's a loop through neutral somehow.

[Folsom]

If I move the ground wire I get minor RF changes.

It seems like the key is in the fact that if the neutral wire from AC is connected to ground then I get massive noise. I can't figure out why, the hot wire to PSU is open at the switch so there is no power coming from PSU that I am aware of.....

There shouldn't even be a complete circuit through transformer with power off.

[hagtech]

Sounds like an Earthing issue - and a radio station not far enough away.  Check for ground loops through power cords / interconnects.  You should not have hum with the BUGLE off.  Or on, for that matter.

jh

[Folsom]

I unsoldered R4 and R7, and now it's just RF.

I do live in a bad Rf area. I might be stuck with it.

Would caps across the RCA inputs be too detrimental? It works well on amp (so my tuner only plays one station at a time haha).

[Folsom]

Impact is greatly improved too.

Trust me, I tried everything on the AC. I opened all my cords, disconnected safety earth (nothing I use has it except the bugle by choice).

The amount of noise in the playback seems lower too.

Maybe I have poor transformer?

[G Georgopoulos]

For rf elimination try using shielded wire,this will work also for hum pick up...

[Folsom]

I use blue jeans cable RCA's. They are coaxial.

I can hear rf in small fans in bathrooms and the one I sleep with. It's bad.

It seems like my RCA's despite shielding, at this proximity, act like antenna. Turntable probably does to.

[poty]

In my opinion there should be a series of filters (common mode and usual hi-freq) on AC mains, minimum input impedances for each device in the chain (of course the output stages should be capable of driving such impedances) and good shielding.

[Folsom]

I have that poty  , I make conditioners. They can't stop all the in system stuff; but they do amazing things.

Like I said, stopping the AC from R4 and R7 killed all hum. The RF might just be circumstantial. A ferrite on the ground wire would probably help.

[poty]

...Like I said, stopping the AC from R4 and R7 killed all hum...

What do you mean about stopping the AC from R4 and R7? Disconnecting mains?

[Folsom]

R4 and R7 bypass the diodes to ground. Hence a loop can form.

[poty]

So, you just deleted them from the circuit and this stopped hum?

[Folsom]

Yea. I can explain it to you, if you like, but in general I'd say whatever it's benefit is that Jim knows, it's not worth it. I am not the first person with hum and Bugle with PSU

[Folsom]

Get this, if the case isn't connected via a .1uf and 150ohm resistor to the ground on Bugle then there is hum before I even twist the power cable into lock (it's neutrik powercon).

There must be a lot of inductance somewhere? The RF is really strong.

It appears that some ferrites on the powercord help a lot.

Not sure about on RCA's.

[Folsom]

Actually the effects of RF ferrites on the power cord have beenn effective like a stereo upgrade.

My building is from like the 1920's or something. We have fuses in our apartments. I suspect that's where the Rf really roles in; ancient wiring and conduit.

[poty]

...you just deleted them (R4, R7) from the circuit and this stopped hum?

Yea.

Well, I can't understand that. Either the transformer works in very tight conditions and additional, even small, load drops voltage to the level that is not appropriate for LM regulators or the resistors are wrong valued and draw excessive current. It cannot be the source for any loops really. I'm not guarding the resistors (while understand their job), but such effect...

if the case isn't connected via a .1uf and 150ohm resistor to the ground on Bugle then there is hum

It is not surprise for me. You said the Bugle is the only place where the whole chain is grounded. Eliminating this only point sure will have effect.

Actually the effects of RF ferrites on the power cord have been effective like a stereo upgrade.

RF ferrites is just simple hi-freq common filter. You said you already have one in the device, or I'm wrong?