Well, if there is no permanent load resistance; if the user has total control via changing plugs, that is actually not a bad feature, so long as one knows about it and knows enough to use the feature properly. (This is in contrast to almost every other phono stage I know about that uses plug-in resistors to alter load, where the added R is in parallel with some permanently installed resistance value, usually 47K ohms. I think there is one other product where the permanent resistor is very high in value, like 1M. That would work too. In that case, any plug in resistance is going to dominate.
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.
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47K is the standard input impedance for a phono section, MM or LOMC. If this were mine I'd using a DVM and measure the resistance between the connections of the RCA jack and see what's there. I'd also use the DVM to see what the RCA plug thingys are as well. You can't just use one value for MM cartridges; its variable depending on the cartridge and the tonearm interconnect cable! Take a look here:http://www.hagtech.com/loading.html 100 ohms isn't a standard either- when a load like that is specified, it suggests that the phono section is vulnerable to the RFI generated by the cartridge messes with the input of the phono section. See that link above. |
http://www.salonav.com/wp-content/uploads/2016/12/05-1.jpg That is a 47pF cap and the "K" is the tolerance of 10% http://kaizerpowerelectronics.dk/theory/capacitor-code-table/ |
Hey Chak, thanks. If it's 47k then the manual is wrong. https://www.musicalfidelity.com/uploads/catalogerfiles/lx-lps/4_LX_LPS_manual_2.pdf Accessories (supplied) Power Supply 2 x 100Ω RCA Plugs - Green Plugs - For MC loading 2 x 47pF RCA Plugs - Blue Plugs - For MM Loading USB Cable |
Mine came with several other sets of loading plugs. I received sets for 200 ohm, 500 and 1K. None offered better sound for any of the cartridges I own, but it’s nice that I can use these plugs with any value resistor I want when I buy a new cartridge. This wasn’t a feature mentioned on the product website so it was a pleasant surprise when I opened the box. I can’t understand why they included them but don’t advertise it. Seems like it would attract buyers. |
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