18 Watt Lite Test Readings?

[tatter75]

Hi everyone!

First post from a novice so please be gentle!

I have just completed building an 18 watt Lite kit (normal channel only and tube rectified) which was bought for me about 15 years ago from Aston Electronics in the UK. They no longer sell kits and I'm sure they used to provide some test voltage readings to verify the build but I can't find them.

Is there a list of expected voltage readings for certain parts of the circuit?

I do seem to have a couple of issues with my build which I will look into but would like to check voltages:
1. The power light doesn't light up (should be an easy fix)
2. If the volume is on zero and the tone is on full I get a loud white noise/hiss sound
3. There's some low volume hum but I reckon that is probably down to wiring

The amp seems much louder than I expected which I suppose is a good thing.

I will attach an image of the layout that I have used, and some photos.

[tatter75]

Just found the test voltage charts in the downloads section!

Any pointers on the white noise issue much appreciated.

[Bieworm]

Just found the test voltage charts in the downloads section!

Any pointers on the white noise issue much appreciated.

Personally I don’t like the layout plan. Ground return wires are way too long imho for instance. If the wires from the input are not shielded, well change them to shielded wires. Ground the shield on only one end at the input and seal off the other end. Let’s start there. Also a sound clip would be helpful

[tatter75]

Thanks, currently the input wires aren’t shielded so I will do that.

I did wonder why the ground point was so far away from the source of the wires! If I still have issues at a later date could things be improved by just drilling a hole in the chassis nearer the board and shortening those 5 ground wires?

[Bieworm]

Shielded input wires are pretty crucial when you want the best signal to noise ratio. Remember that this is an amplifier. It will do its job and amplify the signal you put into it. The noise generated in the early part of the circuit will be amplified several times along with the guitar signal. You might want to try different 12AX7 tubes in the first socket. Some tubes are more quiet than others. Also a 5751 tube is a good and quiet option. But you lose some overdrive, which might be good or bad, depending on what you aim for

There are ground schemes that have proven to be the best for these amps. Follow the link and read up on the advice. Best chance on good results

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