To Aesthetix users

Just realized there's no point in swapping the EL-34s if swapping the power umbilicals makes no difference. And swapping the umbilicals makes no difference - the RF is more in the right channel.

I've just realized two things:

- moving the Io PS power cord around reduces the hum, but not the RF

- the RF problem and the hum may be in the Io tubes. I guess V1/V2 are the candidates for replacement. Perhaps I should try swapping the channel pairs first?

Patrick

Hello, Patrick

You may be getting close. Definitely swap the front end tubes from channel to channel. Make sure you mark them V1A, V2A, V1B,V2B etc to keep things straight. You may have to work through the whole tube complement to find a culprit.

Bonding of the receptcle frame to the box is really not good enough IMO the box is oxidized cadmium plated and you are trying to achieve a good ground...I'd add a wire from the ground terminal of the receptcle to the box if it were me...you still need to check the other end out with an electrician...this point may be minor if there is no ground at the front end anyway.

Try a sheilded ac supply cord from Belden or Volex(P/N 17604) They cost about $15.00 for a 14gauge type from any of the supply houses like Allied Electronics etc.They give similar performance to some of the high priced highend types for a fraction of the cost.

Lift the ground with a cheater to note the result

Try turning down your gain or if you are really adventurous move your equipment around to see the result...clean your contacts!

Jim has always responded to me...he may be busy or sometimes the spam filters don't let you through. You can give a call otherwise.

Nkj: re opening up the main panel for a peek. I can unscrew the circuit-breaker main panel (it was done recently when I had some air conditioning wired installed) and look at the back of the switch which supplies power to the stereo. Is there any way I can tell whether it is properly grounded at the panel just by looking at it? Or would I have to measure continuity from the conduit sheathing to the switch (or the neutral wire)?

Don't worry - I'm an exceedingly cautious person - I won't do anything foolish. I've built a few electronic kits and rewired various electrical things around the house - lamps, light switches, and (as you know) receptacles, but I have not looked at the back of my circuit box.

Best
Patrick

Please do not attempt to enter the service entrance if you are not qualified to do so. Your risk serious injury or death.

When your electrician looks at the service entrance (panel) there would be, in modern set-ups, a buss termination where all grounds go to..usually bare wires or green wires This buss strip is directly bonded to the panel. There is another buss strip where all white(neutral wires) go to this is isolated from the panel and bonds to the neutral main coming in. Your electrician would be able to see the two distinct buss strips indicating a grounded panel.If you do not see this it is unlikely that you have a grounded service. Have your electrician look at how the latest addition to your panel (the AC) has been added. Is there a ground from this branch and where does it go insided the panel?...this could be a clue..

Outside of panel Take a voltmeter, set to AC, measure from the wide prong of a receptlce to the ground ...should be zero if the receptlcle is grounded correctly. Also measure from the ground prong of the receptlce to the narrow bar of the receptcle should be 120vac.

I'm not familiar with your codes or practices in NYC. This is general information. You need an electrician to look at the main entrance of the service wires: should be 2 black & a white and possibly a ground bonded to the neutral dependant on the era and the codes at time of installation.

Just ran a wire from the receptacle's ground screw to a new screw and hole I drilled in the conduit box. As before ratshack wire says there is now a ground.

I have a shielded supply AC cord on order as per your recommendation.

I think I will use an electrician for the next step!

In the meantime I will be searching for Telefunken 12AX7s to try in the Io's front end.

Thanks to everyone in this thread... audio's a journey...

Patrick