Musical Fidelity Phono preamp loading
Thanks. I have gotten that far. There are more loading plugs included. These are open at the back and don’t seem to be a complete circuit without something plugged into them. That’s the mystery. I won’t be buying any other Musical Fidelity products after contacting them and being told to see the dealer. Dealer has no documentation either. |
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 |
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. |
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 |
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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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. |
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. |
