To Aesthetix users

Hello,

A couple of other thoughts:

* You obviously do not have a continuous ground through to the receptcle. If you unscrew the receptcle from the box and leave it in free space then your ratshack tester will show a missing ground. I don't know your electrical code (I'm in Canada) but I understand that in major centres like Chicago and probably NYC conduit is required in commercial/multiunit applications for fire code and protection from pests. If you are comfortable you can mechanically bond a ground wire from the recepticle to the recepticle box with a screw.You'll still have a problem on the other end though with perhaps poor bonding of the conduit to the box... the whole system circa 1955 may not be grounded anyway? An electrician's advice is good here if you are not savy in opening up your main panel for a peek.

* You could try running an extension from your AC outlet to the Io just for fun and see the results.

* If the AC line works (or even if it does not) and you can make the investment in one dedicated circuit back to the panel then this may be worth it to eliminate clicks and pops from other appliances. Decorative panel mold conduit is available to make the run as unobtrusive as possible.

* You are running the Io full out with possibly an improper ground in NYC (RF hell I imagine) so you may have to back off a bit. This is a function of the overall sensitivity of your system from cartridge to speakers and the room interface. I'm thinking this is your real problem!!!

* Try eliminating your power conditioner on the other equipment and see what happens to the hum... make sure you have no other inputs tape,tuner etc connected to your pre. They may be causing a groudloop via the common buss on the pre back to the Io.

* Start swapping cables L-->R and tubes L--R... If you have known good tubes for the PS supply swap them in. If it bothers you enough and you don't want to ship the unit for testing then perhaps buy a complete tube set and try swapping them in (for god's sake mark them first so you don't confuse yourself...ask me how I know)...man I'm getting tired just thinking about it!

The good news is the Io is very silent on my system so I know you can get there with this equipment with proper wire dressing, grounds, and good tubes.

All the best

Thank Nkj. I just opened the receptacle and checked ground with the ratshack tester - and it is just as you describe - grounded when the receptacle is screwed into the conduit box, not when unplugged.

I was going to run a wire from the ground screw to the box as you also suggest, but my multimeter shows continiuty from the ground screw to the receptacle ends, which are firmly screwed to the conduit box anyway, so I don't see the point of a separate wire. Effectively, screwing the receptacle to the box grounds the box, as the ratshack tester shows.

Unfortunately I don't have the skills to check to see whether the conduit is firmly grounded to the circuit breaker box at the other end. It sound like I need to bring an electrician here, and in fact I have been considering a dedicated line for some time.

For now I'm going to replace the receptacle as it was (unless you really tell me a wire from the ground screw on the receptacle to a screw on the conduit box is somehow different from the (ground-continuous) receptacle-ends being firmly screwed onto the box).

Next I'm going to try swapping the Io's power umbilicals, and then the EL-34s, to see if that makes any difference.

I take your point about running the Io all-out in NYC. I probably could use the 72 db setting as well. But the 80 db setting sounds so good in my current system that I'm reluctant to switch.

I haven't been able to get in touch with Jim White yet - he's a hard man to get hold of!

Patrick

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