Is selector switch close to inputs really necessary?

maurycy

Member
2005-12-24 4:34 am
NJ
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.
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
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.

RV5.gif
 

maurycy

Member
2005-12-24 4:34 am
NJ
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.
 
According to me it easier to put the switch close to the input ( one shaft extention and a few small parts ) .. otherwise you will have to use shielded wire from the back to the front panel and this need a lot more work .

An other option is shown below
 

Attachments

  • 100_3144.JPG
    100_3144.JPG
    327 KB · Views: 101
  • 100_3147.JPG
    100_3147.JPG
    321.1 KB · Views: 103