What's The Strangest Thing You've Observed in High-End Audio?

[MylesBAstor]

Here's one for the books!

An audiobuddy many years ago had a system that included an ARC D250Rev amplifier (a darn good sounding amplifier in its day too!) and an ARC SP8 preamplifier. He had a lamp over directly over his preamplifier and you'd get hum in the system if you waved your hand between the preamplifier and the lamp. No, not touching the preamplifier; just placing it between the lamp and electronics. Go figure.

[JCOConnell]

photosensitive?

[atmasphere]

Here's one for the books!

An audiobuddy many years ago had a system that included an ARC D250Rev amplifier (a darn good sounding amplifier in its day too!) and an ARC SP8 preamplifier. He had a lamp over directly over his preamplifier and you'd get hum in the system if you waved your hand between the preamplifier and the lamp. No, not touching the preamplifier; just placing it between the lamp and electronics. Go figure.

Did the lamp have any influence at all? I've seen a number of preamps that would do that (no lamp involved)- particularly if the cover wasn't properly secured.

[Alrainbow]

While at the Nyc audio show a few years back tgey had these huge 5 way horn setup. My expectations were high. once I went inside things quickly hit the floor. I kindly walked over to the man running the room and said.
this looks great when will you have it fixed and ready to hear
there were two men one Asian and one American
the American snapped back at me and it’s fine
I then turned to him and said are you kidding ?
he said no it’s fine and left in a huff. The Asian man said I’m sorry yes it’s broken he blamed it on the cd prayer lol.
he then showed me a spot taped on the floor and said stand here. It was to one side. it got a tiny bit better at times during music passages. i meant no harm or to insult but if you look at me and say it’s great I’m sorry I can’t lol

[ack]

Strangest thing??? Yes, in my system, figured it out just a couple of months ago, after your visit Myles... ever so slight hum in my phono with the preamp volume at or around max, much louder when I attempted to connect phono ground to preamp or DAC chassis.

I run XLR from the arm to RCA phono stage with XLR-to-XLR cables plus XLR-to-RCA adapters (pin1 connected to signal negative) at the phono, plus additional ground wires from the XLR-to-RCA adapters' bodies to phono ground, a short 3 inch distance. Measuring for continuity, phono ground to RCA negative at the phono stage shows they are connected with a 0.1ohm resistance, so no harm with those wires, right???

Wrong was I... apparently that 0.1 resistance is enough for all these troubles... remove those wires and all hum is gone. Goes to show that whatever small ground leak there was before, if amplified some 100dB it can be audible. It also shows that even tiny wire impedance variations can create ever so small ground leaks - reason I use the exact same length, brand and model power cords, and even that may not be enough.

Eventually, that's when I got special XLR-to-RCA adapters with Pin1 floating but with a ground wire coming out of Pin1, which was then routed to phono ground. In other words, the problem was between the original common adapters' Pin1-to-Pin3 connection and that 0.1ohm resistive impedance

[MylesBAstor]

Did the lamp have any influence at all? I've seen a number of preamps that would do that (no lamp involved)- particularly if the cover wasn't properly secured.

Yes, the lamp had to be on. And the top of the SP8 was properly screwed down. But I know what you’re getting at. IIRC Enid (?) said ARC preamps sounded better with their tops off.

[CJSPU]

That’s not a surprise to me. The vacuum Tubes in amps and preamps work like antennas that capture every kind of electrical noise. If I left a pair of cables connected only in one side and the other side free without being connected I get immediately noise in my tube amp or tube preamp. High sensitive…

[CJSPU]

The most unexpected experience I had,
not necessarily strange happened recently.
I changed all my rca connectors, rca sockets, binding posts, terminal posts, internal wire in all amps, preamps and the internal tonearm cable for WBT pure silver AG nextgen connectors and pure silver wire.
In every signal pathway that I could I change for pure silver. The difference is indescritably!. Much, much better!!. I recall that the differences between my ortofon a95 and the ortofon spu Royal gm mkii were almost not perceptible ( both have the replicant stylus). But after these upgrades the A95 revealed so superior and in another league of its own. High end it’s all about electronics…

[atmasphere]

Yes, the lamp had to be on. And the top of the SP8 was properly screwed down. But I know what you’re getting at. IIRC Enid (?) said ARC preamps sounded better with their tops off.

If the panel was painted or anodized, and the screws didn't break through the insulation caused by either, the result would be as CJSPU suggests- the panel would become a noise source rather than shielding. There used to be certain zener diodes that were light sensitive back in the 1980s and 1990s. Its easy to imagine a florescent lamp giving a circuit with them installed a pretty hard time.