I'm building a pre-amp with a phono stage and 3 other inputs.
Both the pre and phono run at + and -15v.
Current draw shouldn't be a problem.
Do I need to use some kind of switch to turn on phono or just leave it connected all the time?😕
Thanks
Both the pre and phono run at + and -15v.
Current draw shouldn't be a problem.
Do I need to use some kind of switch to turn on phono or just leave it connected all the time?😕
Thanks
Looking at your voltage I'm assuming solid state? If so, I leave my pass pearl on all the time, doesn't hurt anything.
Thanks.
Both the pre and phono amps are op-amp based, which I should have stated in my original post.
I guess I'll just wire it to be in the on state all the time the pre is running.
Don't think it will hurt anything just wanted more experienced opinions.
Rod Elliott's, by any chance? 🙂
I would certainly include a mains on/off switch (which would switch power to both preamp and phono stage) but I would leave it switched on 24x7, unless I was going away.
Regards,
Andy
Thanks Andy
Yes based around Rod Elliot's design except I'm going to use an external PS.
I think it was one of the revisions to run off dc.
Hardest part has been what to use as connectors for PS. I'm using Plastic box and so far I'm deciding on simple binding posts.
I'd like to have a nice male - female arrangement but haven't found a suitable one. This is all kind of new to me.
John
Actually it hurts the capacitors in the power supply.
Think green, turn it off when not in use!
power switch for lightning protection
I don't know what part of the US you are in but there is a lot of lightning strikes where I am. I've had lightning explode the neon bulb in the ST120 power switch and nothing else. I've had lightning blow up the capacitor across the power switch in my PAS2, and nothing else. The refrigerator or A/C probably damps the lightning down some but still. A two pole switch that disconnects power and neutral is good. If it is in a power strip and not the preamp chassis, that is fine. Blue MOS arrestors salvaged from dead PC power supplies from both hot and neutral to the safety ground are a good idea now- I have back installed these on the PAS2 and the ST120. They weren't invented until the 80's. They will have a regulatory approval logo on them, UL in US, CSA in canada, VDE in Europe, etc. for installation on the power line. A .47 uf regulatory approved capacitor across the hot of the power switch is also a good idea. These can also be salvaged from the dead PC power supply. The cap reduces or eliminates turn off pop.
Cheap square connectors with shielded pins rated for 250 VAC can be bought in small quantities from mcmaster.com. They are molex. It takes a while to form the crimp without the $150 tool but is doable particularly with a $20 crimp tool for automotive type terminals. You have to do the strain relief separately without the $150 tool. Square connectors are good because you can drill 4 holes in your chassis and connect the dots with a sabre saw. Drilling big round holes in sheet metal is a bit difficult even if you do buy the $35 drill bit. It tends to bend the metal when it snags at the end, also break the expensive bit. I do big holes in sheet metal now mostly by connecting the dots on small holes, and using a die grinder with a carbide tree bit to clean up. Use safety glasses.
I don't know what part of the US you are in but there is a lot of lightning strikes where I am. I've had lightning explode the neon bulb in the ST120 power switch and nothing else. I've had lightning blow up the capacitor across the power switch in my PAS2, and nothing else. The refrigerator or A/C probably damps the lightning down some but still. A two pole switch that disconnects power and neutral is good. If it is in a power strip and not the preamp chassis, that is fine. Blue MOS arrestors salvaged from dead PC power supplies from both hot and neutral to the safety ground are a good idea now- I have back installed these on the PAS2 and the ST120. They weren't invented until the 80's. They will have a regulatory approval logo on them, UL in US, CSA in canada, VDE in Europe, etc. for installation on the power line. A .47 uf regulatory approved capacitor across the hot of the power switch is also a good idea. These can also be salvaged from the dead PC power supply. The cap reduces or eliminates turn off pop.
Cheap square connectors with shielded pins rated for 250 VAC can be bought in small quantities from mcmaster.com. They are molex. It takes a while to form the crimp without the $150 tool but is doable particularly with a $20 crimp tool for automotive type terminals. You have to do the strain relief separately without the $150 tool. Square connectors are good because you can drill 4 holes in your chassis and connect the dots with a sabre saw. Drilling big round holes in sheet metal is a bit difficult even if you do buy the $35 drill bit. It tends to bend the metal when it snags at the end, also break the expensive bit. I do big holes in sheet metal now mostly by connecting the dots on small holes, and using a die grinder with a carbide tree bit to clean up. Use safety glasses.
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hi
Electronic parts do not last forever. If you leave the phono stage on all the time you will be lucky to get more than a few years use from the electronic parts, especially the capacitors in the power supply. As the parts age/wear it is possible that a failure will occur but it is more likely that the phone stage will just sound less clear and less dynamic. It will last longer if you only switch it on when required.
If you do still plan to leave the phono stage on all the time you will extend the life of the parts if you operate the parts well within their operating zone and at a low temperature.
Don
Electronic parts do not last forever. If you leave the phono stage on all the time you will be lucky to get more than a few years use from the electronic parts, especially the capacitors in the power supply. As the parts age/wear it is possible that a failure will occur but it is more likely that the phone stage will just sound less clear and less dynamic. It will last longer if you only switch it on when required.
If you do still plan to leave the phono stage on all the time you will extend the life of the parts if you operate the parts well within their operating zone and at a low temperature.
Don
It won't be on constantly. Just when the pre is powered up.
Trying to make it simple as possible since both pre and phono amp run off the same voltage and use very little current. Op-amps for both.
Switch will be on the seperate PS.
I'm on the east coast of FLA so I'm familiar with lightning😱😱
Got hit a couple months ago overnight but was very lucky. Only thing it zapped was modem and T-100 in computer. No other damage.😀😀
Thanks Joe
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