Search results

I generally agree with the recommendations you give, but RF is defined as 20kHz to 300GHz. What's being coupled into Peter's system is AF - audio frequency - noise from the 60Hz AC line. Peter - you can put a dead short across the audio input lines and do no harm.

Ha! Yes! Damn that induced noise. It's everywhere - everywhere, I say. Night and Day. Relentless...

So? Agree that no current is running through that particular wire, but it can, and does inject noise in your system electromagnetically. That AC field in that wire is expanding and collapsing at 60Hz. Any wire nearby will have a voltage induced in it.

Peter, if those wires going to the switch are still in the circuit, it will still create an EM field that can induce (either capacitively or inductively - it doesn't matter, probably some of both) into the input. They, the wires going to the switch, have to be totally disconnected from the AC...

But can you confirm the frequency?

Peter, looking at the scope shot you provided, it looks to me, if I'm reading it right, the residual noise is roughly 2.5-3.0 mV P-P, at about 240 Hz. Can you confirm that? So, if you're listening to music at 1 watt with 8 ohm speakers, my calculations have that residual noise down about 70dB...

Agree. Twisting them should help and shielded twisted pair perhaps even more (with the shield grounded at one end only). Those run close to the input op amps on the PL14/20 board, so that may be where the induced hum/noise is coming from. Perhaps you can try bypassing the thermal switch...

This thread reminds me of a thread I follow on a UK forum for restoring old radios. The thread is called "The Audiophoolery Thread" and is now over 65 pages. Folks submit whatever latest audio snake oil they've found on the web. Here's one for your enjoyment...

That is so cool... The only thing I'd rather restore is an airplane.

I think the red tractor is pretty cool too.

A Network Analyzer would be needed to make an accurate measurement. Also, to be clear, the measurement is from the center conductor to the outer shield and both connections would be made at one end. Generally a DVM's measurement of capacitance is done at one relatively low freq - 10 to 100kHz...

Of all the recent super bowls that I can think of, this one has to be the hardest to handicap. Both teams are quite capable of scoring a lot of points in a hurry - no lead is safe. I'm attending a SB party hosted by an old college friend who lives in KC, so I'll be rooting for them, but as far...

I thought of putting some 30v zeners across them, but if you guys say it’s alright then it must be alright. I trust you guys... well sometimes.

Meters were not happy with you. At what point do they give up the ghost?

Check out the Volumio here: https://volumio.org/volumio-overview/ I put one of these together with a Raspberry PI a couple of years ago after I had ripped my CDs to a NAD. It works really well. We often use it when we have the kids or friends over and I can hand them my iPad and let them...

So, essentially for a PL400, it's okay to peg the shit out of the meter when you're playing music over 100W?

Amazing. It's actually what I measured. For some reason I'm always a bit surprised when science works. Sorry for covering old ground. I'm going to go find the thread, so I can ask more questions.

Welcome. Having just completed a WOPL restoration of a 400, I can vouch for the first rate kit and instructions you get. Looking forward to following your thread.

Ahh... So it's voltage, not power. Appreciate the hint.

Perfect.