gparker777 Posted August 10, 2020 Share Posted August 10, 2020 Above is an image of the MC/MC(Load) section of my phono preamp. I want to solder in resister loads internally, rather than using external plugs and just want to make sure I do this correctly as I don't have access to a schematic (and no help from manufacturer). My assumption is that I just need to solder the chosen resister load between the Shield trace and tip (shown with little red circles) to achieve the chosen loading, however I was confused why the previous solder point was so far away - wouldn't it be better to solder into the closer Via (white circle) and keep the resister lead length short to prevent pick up of any unwanted noise? Link to comment Share on other sites More sharing options...
soundbyte Posted August 10, 2020 Share Posted August 10, 2020 I would examine using the elliptical shaped plated through holes to the left of the nut/s if you want short leads, larger pad easier to solder and larger pads not so easy to damage? Link to comment Share on other sites More sharing options...
andyr Posted August 10, 2020 Share Posted August 10, 2020 Soldering in a resistor is a baaaad idea, I suggest - as it means your load is then fixed .... and you'll probably have to swap the resistor out for a different value when you change the cart. Why do you consider using load plugs is not desirable? Andy 1 Link to comment Share on other sites More sharing options...
soundbyte Posted August 10, 2020 Share Posted August 10, 2020 The requirement to change resistors was not mentioned but can easily be accommodated by using a longer lead on the board side of the the first resistor/s installed. When you need to change values, cut the installed resistor at the junction of the resistor body and lead going to the board, then solder the new resistor to the lead coming from the board. You could also unsolder the wire/s on the connector/s, remove the nut and put in place a suitable solder lug, replace the nut, resolder the wire and solder in new resistor/s to the new solder lug/s. Link to comment Share on other sites More sharing options...
Decky Posted August 10, 2020 Share Posted August 10, 2020 Since you started soldering you might consider going a step further and putting a small PCB inside with a resistor ladder and a DIP switch. This Pass Labs X15 setting will give you a decent idea what you need. Capacitance setting is only for snobs so you don't need that . Link to comment Share on other sites More sharing options...
andyr Posted August 10, 2020 Share Posted August 10, 2020 (edited) 1 hour ago, soundbyte said: The requirement to change resistors was not mentioned but can easily be accommodated by using a longer lead on the board side of the the first resistor/s installed. When you need to change values, cut the installed resistor at the junction of the resistor body and lead going to the board, then solder the new resistor to the lead coming from the board. You could also unsolder the wire/s on the connector/s, remove the nut and put in place a suitable solder lug, replace the nut, resolder the wire and solder in new resistor/s to the new solder lug/s. Mmmm - very complicated. Much simpler is to have a second pair of input RCAs (in parallel). The 1st pair is for the phono cable ... the 2nd pair for load plugs (which act in parallel with the phono stage's default 47K.) That's the way I build my 'Muse', anyway. 37 minutes ago, Decky said: Capacitance setting is only for snobs so you don't need that . BS! Correct capacitance loading is vital for MM carts ... but unimportant for LOMC carts. Andy Edited August 10, 2020 by andyr Link to comment Share on other sites More sharing options...
gparker777 Posted August 10, 2020 Author Share Posted August 10, 2020 3 minutes ago, andyr said: Mmmm - very complicated. Much simpler is to have a second pair of input RCAs (in parallel). The 1st pair is for the phono cable ... the 2nd pair for load plugs (which act in parallel with the phono stage's default 47K.) Andy Are you talk about something like this Andy? Link to comment Share on other sites More sharing options...
andyr Posted August 10, 2020 Share Posted August 10, 2020 1 minute ago, gparker777 said: Are you talk about something like this Andy? Well, sure - that's a good solution, gp - if you don't have 2 parallel pairs of input RCAs on your phono stage. Or 3 pairs in the case of a MM phono stage - to allow capacitance loading adjustments as well as resistance loading adjustments. (Not all MMs or HOMCs sound their best at 47K! ) Andy Link to comment Share on other sites More sharing options...
Decky Posted August 10, 2020 Share Posted August 10, 2020 @andyr it was just a joke. He can start with the R loading and then decide if anything extra works for him or not. 1 Link to comment Share on other sites More sharing options...
andyr Posted August 10, 2020 Share Posted August 10, 2020 4 minutes ago, Decky said: @andyr it was just a joke. He can start with the R loading and then decide if anything extra works for him or not. Ummm, from your comment, D ... I'm not sure whether you were joking ... or simply ignorant. Sure ... start with the R loading - which is most commonly applied to LOMCs. However: MMs can also sound better at a non-47K R loading. and they most certainly have an optimum C loading (which MCs do not). Andy Link to comment Share on other sites More sharing options...
bikecrank Posted August 10, 2020 Share Posted August 10, 2020 Rather than solder resistors into the PCB, you could take the same approach used by Lehmann Audio in their Black Cube Statement, where a couple of machined pin IC sockets are soldered in each channel of the PCB to enable easy insertion (and removal) of loading resistors. The sockets can be obtained by cutting the plastic away from individual pins in a strip. A picture is worth a thousand words, apparently, so hopefully the attached images will make this clearer. Link to comment Share on other sites More sharing options...
andyr Posted August 10, 2020 Share Posted August 10, 2020 9 hours ago, nbaker said: Rather than solder resistors into the PCB, you could take the same approach used by Lehmann Audio in their Black Cube Statement, where a couple of machined pin IC sockets are soldered in each channel of the PCB to enable easy insertion (and removal) of loading resistors. The sockets can be obtained by cutting the plastic away from individual pins in a strip. Great idea - provided the pin sockets hold the resistor leads tightly. An alternative is the (screw-down) Phoenix connectors, which I sometimes use. Andy Link to comment Share on other sites More sharing options...
soundbyte Posted August 11, 2020 Share Posted August 11, 2020 23 hours ago, gparker777 said: I want to solder in resister loads internally, rather than using external plugs OP wants to solder, no external plugs SO.... 20 hours ago, gparker777 said: Are you talk about something like this Andy? This suggestion or something like it is Simple? This suggestion or something like it is Complicated? I must be in another universe? By all means solder the resistors inside your equipment. My thoughts are that you take care to be able to return the equipment to standard if not the result that you are looking for. Link to comment Share on other sites More sharing options...
Warren Jones Posted August 11, 2020 Share Posted August 11, 2020 On 10/08/2020 at 3:44 PM, gparker777 said: Above is an image of the MC/MC(Load) section of my phono preamp. I want to solder in resister loads internally, rather than using external plugs and just want to make sure I do this correctly as I don't have access to a schematic (and no help from manufacturer). My assumption is that I just need to solder the chosen resister load between the Shield trace and tip (shown with little red circles) to achieve the chosen loading, however I was confused why the previous solder point was so far away - wouldn't it be better to solder into the closer Via (white circle) and keep the resister lead length short to prevent pick up of any unwanted noise? You have 2 sets of RCA sockets in parallel why not just use external loading plugs in the second RCA socket. Load R is easily changed then. Were you planning to remove the 47k or add R in parallel if in parallel do you know how to calculate the total R of parallel resistors. Also keeping the leads very short will not have a huge effect as the R is too low. it's not until R in the MOhms that the resistor will become an antenna. Link to comment Share on other sites More sharing options...
gparker777 Posted August 12, 2020 Author Share Posted August 12, 2020 Thanks all for the responses to my query and some great suggestions. Because I had two MC inputs, I was going to solder in a 47k resister input into the one on the Right hand side (referring to photo) to create another MM input and then still have the MC if needed later. However, Warren you right, I can build the loading plugs (like andyr has done in the thread below) and play around with different loadings as needed without worrying about internal soldering so will take that approach. Link to comment Share on other sites More sharing options...
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