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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

SimpleSE - Switches, Wire, IEC, Jacks

I'm resuming my SimpleSE project (after a few stressful weeks of school took over), and was curious if anyone has suggestions for power or mode switches, IEC connector, RCA jacks, volume pot, and Speaker connectors.

I'm curious if lit switches are frowned upon (lamp, LED, neon) due to causing noise. Also, is there a suggested wire size recommendation for the external wiring to switches and posts? Any suggested type of coax for the input jacks?

Since this is my first project, I only know of a few good part sources so far, so any input is appreciated. I'm hoping to buy these so I can finish chassis fabrication and actually get to listen to my amp! :)

I also have access to a machine shop, so if there are any recommended bore diameters for the tubes I can probably make them any size I want, with great precision. Any other chassis hints/tips would be great. I'm planning on doing wood surround with Aluminum top plate.
For power switches I've used simple toggle switches but lately have been using illuminated switches. The amps I've put them in are hum-free and quiet so I wouldn't worry about adding noise. Just make sure to tightly twist the AC wires and keep them away from signal wires.

A rotary switch (2 pole, and however many positions you want for sources. I use non-shorting switches, others use make-before-break. I've used 4 pole switches and switched the grounds and 2 pole switches without switching the grounds and can't tell the difference sonically.

I've used cheap Radio Shack 100K log pots for volume controls and they work fine. Recently though I've used Alps and Noble pots and again they work well.

I prefer to use isolated RCA jacks for inputs. That way you can choose the point where you want the grounds connected. If you have some RCAs that are not isolated you can mount them on a sheet of acrylic then mount the acrylic to the chassis.

For speaker connections dual binding posts are nice but I've used individual posts as well. As with the input jacks don't connect the common or ground post to the chassis.
for IEC jacks, I've been using the 'multi' IEC jack that has AC switching, fuses and RF/EMI filtering in one unit. Available at Allied, Mouser, Digikey, etc.

Digikey also has PEC Carbon pots which are reported to be very good for volume control use. My own personal preamp I use a Goldpoint stepped attenuator. For some budget projects I've used Alps and Noble with good success.

RCAs and Banana Jack I use some inexpensive gold plate ones - these can be found on Flea-Bay for low cost.

Wire I like teflon coated - it doesn't melt like PVC if you get a little overzealous with the soldering iron. 18-21awg should be fine for input wiring. Teflon coated can be hard to strip and there are special wire strippers available for this type of insulation.

For switching I will often use a pricey Elma (very dependable), but I've also use a simple TOCO DPDT switch depending on how many inputs I'm using.

just my .02c
Okay, after way too much wasted time I'm finally done with this quarter of school and ready to buy the remaining parts. What brands are suggested for the IEC jacks? I'm having trouble finding some of the ones with all the filtering built in. Are those pretty expensive?

I'm mainly looking for switches for Triode/UL, Power on/off, etc.

Is there a good source for smaller quantities of the hookup wire? I'm thinking I will go with the Teflon since I have experience working with it, and it is very nice.

Can anyone tell me what style coax they use for the input signals? Is the type very critical?

Zap said:

What brands are suggested for the IEC jacks? I'm having trouble finding some of the ones with all the filtering built in. Are those pretty expensive?

I'm mainly looking for switches for Triode/UL, Power on/off, etc.


I bought a bunch of IEC inlets online at All Electronics. They had built-in RFI/EMI filters and were in metal jackets (the external part was still black plastic of standard dimensions). IIRC they cost about $3 each.

For power switches I've also purchased illuminated rocker switches from the same source for a couple bucks each. Easy to install since they only require a round hole. If you don't need illumination just about any switch rated for your mains voltage should be fine.

For the triode/ul switch you need at least a DPDT toggle, avoid the ones that have a center off position for this duty. If you want a choice of three modes, triode/ul/pentode then you need either a 3P3T toggle (fairly rare at least in the surplus market) or a 2 pole, 3 position rotary switch.