I was in the process of installing BACCH4Mac and a pink noise signal was sent to the left speaker. The inventor of BACCH, Dr. Chouieri (Head of the Princeton 3D Audio and Applied Acoustics Lab, and head of the Electric Propulsion and Plasma Dynamics Lab as well…very bright, to put it mildly) told me there should be no noise coming from the right channel when he applied a signal only to the left. The same issue occurred when he sent a signal to the right-only.
I have a NAC252, with SupercapDR and 250DR.
Apparently this is unusual and it killed the installation.
Is this crossover leakage a design feature, or is something in need of repairs?
Well your colleague should have said in theory there should be no noise crossing channels, but in practice because of the close proximity of the channel electronics and the shared powerline and ground planes there will be a small amount leakage across the channels. It should however be very low, if it’s not very low then it points to a fault, possibly a wiring fault somewhere, or as said a mono switch pressed somewhere….
Now for headphone amps, there is often a technique called cross feed used, and this blends a small amount of certain frequencies across both channels. This simulates how you hear stereo sounds when using headphones. Typically cross feed circuitry can be switched off, if present and not required.
The crosstalk could be from preamp, and/or power amp (unless you use separate power amps for each channel), latter minimised by monoblock design, and/or also from interconnect/SNAIC. The amount of crosstalk is often given in amp specs, more commonly referenced as channel separation, the aim being as low as possible (large value of separation dB), but with stereo music listening it is largely academic as the speaker arrangement and room have greater audible effect in practical terms, so it is not a value often considered as of great significance in amp choice. I’ve never heard of it being deliberately built in other than in some headphone products as Simon mentioned.
Very low cross talk specifications is overated. Proper music is mixed that the R and L channels share a lot of common information. And even a $25,000 exotic MC cartridge will have at best around 29dB of channel separation…at least 80dB more than some of the best specced preamps and amps, and yet still can sound brilliant with fantastic imaging.
Our ears are also full of cross-talk!
Some years ago I knocked up a cross feed circuit (with bypass switch). It sat in the headphones chain for a number of years, and I would play with it from time to time. Ultimately though, I decided I preferred the sound when in bypass mode, so I took it out.
Well now it’s getting muddled as do all things audio.
I spoke to Naim and the guy said there might be a few microvolts, but really noting audible. He said the expert would call me back, and that has not happened.
Then I spoke to Chris West of AV Options in Chicago who may be the last Olive/Chrome Naim genius standing, who was hired by J. Vereker 30+ years ago, and he told me to pull one of the RCA plugs out of the DAC and see if I heard anything from that speaker. Nothing. I reversed it: Nothing.
So no Xtalk.
So it’s either in the way Prof. C. induced the signal, or I heard some kind of passive resonance, or else it’s in my power amp. But they all say the power amp is HIGHLY unlikely to be the culprit.
I’ll try again. Stay tuned if you are so inclined. Thank you for your suggestions. Happy Thanksgiving to all in the US. And for you Brits, muddle through as is your wont.