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Musical Fidelity Phono preamp loading

I just bought a Musical Fidelity LX-LPS. They are cheap now and I was wanting to use it to experiment with cartridge loading. It comes with 5 different loading plugs that you put into rca jacks in the back. I think. Does anyone have experience with this unit? It comes with no information on how to use the supplied rca loading plugs. There are two black ones that are closed-back lugs. Instructions say the blue ringed ones are for typical MM carts, and the green ringed ones are for typical MC carts. That’s all the information on those. Then there are three sets of open backed rca lugs. The sheet says the white ones are 1K. Ohms I guess. The red ones are listed as 200 ohm. The yellow ones are 500 ohm. But these are open at the back and accept an rca plug. The circuit is not complete unless something gets plugged into them. Would the rca phono outputs get plugged into these? Or the black lugs?  So far the test MM and MC cartridges I’m using sound best without the black plugs inserted. They seem to attenuate output. That is my guess. I have no idea how to use the other lugs to see what they do.  I’ve contacted the manufacturer but they just said contact the dealer. I contacted music direct but not heard back. Given that this is the weekend I’m not expecting to hear from them. So if any of you can help I’d like to experiment with this unit this weekend. Maybe I’m the  only one on the planet that doesn’t just know how to use this thing, but I’m still surprised there is zero instructions with the unit. And no review or other online instructions I can find. Thanks for any tips on use. 
vinylfan62
imhififan's avatar
imhififan
2,181 posts
 
100Ω RCA Plugs (Green for MC loading)
47pF RCA Plugs (Blue for MM loading)

You can custom the loading plug using different value resistor/capacitor.

http://www.salonav.com/wp-content/uploads/2016/12/05-1.jpg

http://www.salonav.com/wp-content/uploads/2016/12/06-1.jpg
vinylfan62 OP
119 posts
 
Thanks. I did figure out the black lugs with blue or green rings. It was the other three sets that I was unsure about how I would use them. I think I have it now. Amazing that a company would put this much thought into a product and then not document or support it. I have bought from the in the past, but I won’t be buying from Musical Fidelity again. 
davidwbrown
3 posts
 
All above correct. The dealers should have enough competence to have advised this to begin with. Though an oversight on the manual - wholly agreed. 

It came with 2 x 100 ohm RCA Plugs (Green for MC loading), and 2 x 47pF RCA Plugs (Blue for MM loading).

Another oversight from the Manual - the MC input impedance of  the LX2-LPS stated in manual is wrong, it should be approx 3.8K. This suits higher output cartridges, and am quite sure most if not all will sound fine with this “somewhat low impedance” loading.

The product was a pre takeover product, and I can assure you now that Audio Tuning are in charge support is a lot better, and there are new and exciting products in the pipeline. So please don't dismiss a brand based on an older product and poor support from a dealer ! The support network is a lot better now. If the dealer had contacted MF HQ they should have been given the above information
chakster's avatar
chakster
6,144 posts
 
 


47k Ohm (not pF) 
lewm
13,030 posts
 
I hope you are correct, Chak.  That was my thought as well.  It would seem that with no plug installed, there is no load resistance.  In other words, there is no permanently installed load resistor at all between the gate and ground of the input transistor in the phono section (assuming the unit is solid state).  Is that correct, for those of the responders who know something about this unit? 
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