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AR SP-10 two phono inputs problem

Yungdave

Yungdave

New Member
I've got an Audio Research SP-10 preamp. Never had the "need" for two turntables, but I lucked into a decent super cheap one the other day and decided to hook it up to my system. Problem created! Can barely hear the new one on "Phono2" and when I switch to "Phono 1", the output is cut by about 30%. Bad inputs or switch or what? I'm estimating I haven't moved the phono switch for several years.
 
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Had you previously been using a turntable with the preamp without difficulty?

While it is possible that the Phono Input Selector switch is dirty or defective, I think it unlikely as this switch uses four individual sets of contacts for each channel to ensure lowest noise and best signal transfer. Mind you,after a couple of years of inactivity, even the best switches can oxidize.

Try a light cleaning (meaning applying a couple of drops directly into the switch contacts; don't go spraying the stuff willy-nilly and getting overspray everywhere. Accuracy is your friend here:)) with a top quality control cleaner, preferably one that contains a lubricant / anti-oxidant additive.Also, Give the RCA inputs, jacks and plugs, the same treatment.
 
so in phono 1 mode with 2 tables connected, the output is lower than with just the one turntable connected to phono 1 ? Has to be some switch or wiring problem. Guessing both inputs are active at the same time and phono 2 disconnects them for whatever reason. Sounds like someone has been inside this and meddled around.
 
Which Red and Which Bronze? These colors are used in a number of lines from Ortofon

What is the switch position of the impedance switch? It can be tailored for a specific cartridge. Maybe the other cartridge doesn't like the switch settings.

For the 100k and 47k higher output cartridges will work for the 100, 30 and 10 settings the lower output cartridges should work. I'm guessing you have tried different settings of this control.

I strongly recommend moving all controls full range a dozen times or more on a regular basis, couple times a year. This will refresh the electrical connections. But this is a different issue. Back to your phono issue.

Let us know which ortofons or post pics and then the impedance switch position making a difference.
 
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