I am building ESP's P88 preamplifier. How crucial is it to have the selector switch close to the back where the input RCAs are? Is the 10" wire length (front to back) really going to noticeably degrade the sound? I am asking because I will need to do some real remodeling to accommodate shaft so I can put the selector all the way in the back.
High Quality Audio Preamp
The project description gives the reasons for the rear arrangement, so it's a matter of deciding whether easy construction or best performance is your priority. The author has considerable expertise in pro. audio so for the best DIY results, his recommendation will be worth the extra effort.
On the other hand, the power supply noise issue is minimal using an external transformer and many people don't use the other in/out lines since they may only have one or two sources. The multiple extra lengths of long wiring up and back from a front switch arrangement may then just lay around unused and not become a significant noise or crosstalk problem after all.
Incidentally, you don't have to make a professional engineering standard shaft extension to get good results. I've even used 1/4" dowel for the extension and an old pot. for the front panel brass shaft bushing. You can't pick it other than in a slight delay when switching. You will need to fit a plain hole knob with a set screw to any plain shaft though.
The project description gives the reasons for the rear arrangement, so it's a matter of deciding whether easy construction or best performance is your priority. The author has considerable expertise in pro. audio so for the best DIY results, his recommendation will be worth the extra effort.
On the other hand, the power supply noise issue is minimal using an external transformer and many people don't use the other in/out lines since they may only have one or two sources. The multiple extra lengths of long wiring up and back from a front switch arrangement may then just lay around unused and not become a significant noise or crosstalk problem after all.
Incidentally, you don't have to make a professional engineering standard shaft extension to get good results. I've even used 1/4" dowel for the extension and an old pot. for the front panel brass shaft bushing. You can't pick it other than in a slight delay when switching. You will need to fit a plain hole knob with a set screw to any plain shaft though.
Technically I have to agree, but I still have a preference to locate the switch at the back panel right next to (almost touching) the input sockets.
Most commercial amps dont bother. Use good quality screened cable and you'll not notice the difference i'll bet.
Thanks for replying. I will see if I can rearrange the insides to accommodate extension shaft.
The enclosure will have 4 inputs but only two are going to be used (phono and aux). The difference between the recommended build by ESP and mine is that I will have small trafo in the enclosure. The good thing is that the enclosure has two divided compartments so technically power supply section is going to be shielded from the rest of the preamplifier.
The enclosure will have 4 inputs but only two are going to be used (phono and aux). The difference between the recommended build by ESP and mine is that I will have small trafo in the enclosure. The good thing is that the enclosure has two divided compartments so technically power supply section is going to be shielded from the rest of the preamplifier.
Shielded wires are not "a lot more work". Even a short connection to the switch should be shielded, so all you need is slightly longer cables. Much less work than arranging a switch shaft extension!
Outpu stage of this preamp use 200 mA @ plus & minus 20 volts .... 8 watts ...
see pitchfork thread
see pitchfork thread
I have built pre-amp with no input connects. I just used captive RCA cables wired directly to the selector switch.
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