[Tyson]

Hi all,
I just got a Mapletree 2A SE second hand, and I notice that there's channel crosstalk - when I have the source switch set to listen to music, I still get some very low level sound bleeding over from my TV, which is plugged into a different input. 

What could cause this, and what can I do to eliminate it?

[Watson]

With the Mapletree amps you have to put shorting plugs on the unused inputs on the back otherwise you'll get crosstalk between sources.

[rajacat]

Hi,

I installed a stepped attenuator in my Mapletree Line 3a and experienced better separation and sound quality. Mapletree now offers this as an option. Maybe a better selector switch would help with the sound bleed over problem.

-Roy

[JoshK]

Simple way to remove cross-talk between sources is to put the two sources more than 1 source away, i.e. on input 1 and 3 and leave two empty (Morgan Jones suggests this).  You can try this and see if it helps.  Easy experiment.  Or get a better source selector.  I think it can sometimes be through grounds since most preamps don't switch grounds, just the hots. 

[Tyson]

Yep, tried putting them farther apart, and I plugged in inputs in to all 3 - Duet on Line 1, PS3 on Line 2, and Satellite TV on Line 3.  Helps quite a bit.  Still a tiny bit of crosstalk, but much lower in level now.

I also pinged Dr. Lloyd on this and I think his reply is worth putting here, in case anyone else has a similar issue:

The feed-through is due to parasitic capacitance between the switch contacts. It is possible to wire the unused switch sections so as to ground one of the inputs when another is active. I can only do this with one pair of inputs. Of course, the other solution is not to have two sources active during serious listening.

[JoshK]

Precisely what Dr. Lloyd said.  The more than 1 section away is to lower the capacitive coupling affect.  The better source selector is to minimize the stray capacitance.  In Morgan Jones' book, he uses a 6 input selector switch for 3 inputs and leaves the other three empty (ones in between).  Nice for muting (selecting in between) and for reducing cross-talk.

[*Scotty*]

Part of your cross-talk problem may be caused by how the preamp is wired from the back panel to the selector switch.
Mapletree selector switch wire routing.


Superphon  Rev III Wiring

Cross-talk results from that nice, neat bundling of the wires from the rca jacks to the selector switch via capacitive coupling between the wires.
You might try snipping the tywrap on the wire bundle and physically seperating the wires from one another.
Scotty