Hello. I have a adcom preamp with only a single phono input. I have tube amps and decent speakers. I got an Alexandra 2 and also a homebuilt DIY table. I’d love to have a phono source selector to switch between the two but hear about noise introduced by sloppy switches. Any suggestions for an input or should I get a tube phono preamp? Recommendations.
Thanks.
Thanks.
Find high quality 4-pole switch with gold plated contacts, then each of L and R can use two poles paralleled for better reliability. Many switches are designed for power rather than signal and the contact meterials are chosen for robustness and high current, not low-level signals, and often oxidize over time unless several mA flow through the switch (the arcing blasts through the oxide). Gold doesn't oxidize.
You could use signal relays too, and have a cheap switch to energize the relay...
You could use signal relays too, and have a cheap switch to energize the relay...
Thanks for the info. I can definitely build a box. Then I start to over think wires rca jacks switch and or relays. Do you know of an off the shelf solution that’s good? I saw a rec-o-kut one for $55. But don’t know if it’s good or for double that I can get something nice. I’m on the fence. On the other hand a nice DIY box that matches the style of my DIY table would be fitting. Any recommendations on specific switches and rca connections and internal wire. I’ll also need a central ground point.
Datasheets for switches and relays will explain which part numbers are the gold-plated version - thick gold plate is needed for frequent use, "gold flash" is much thinner and typically used for infrequently plugged connectors. There are literally 100,000's of switches and signal relays out there, but companies like Digi-key and Mouser make parametric search relatively easy these days.
For connectors the same applies, thick gold plate, reputable manufacture, has a datasheet...
For connectors the same applies, thick gold plate, reputable manufacture, has a datasheet...
Another thing you may want to do is remove the caps from the phono input of the adcom and move them to before the switch/relay. That way you can adjust the cap size for different carts. Some cart's like some AT's like very low cap (<150pf) which usually means no cap at all in the phono when you factor in cabling capacitance. Many other cart's want to see around 300pf which means around a 150-200pf cap on the phono in.