5E3 Prototype One

After deciding¬† to have a crack at Guitar amps, I settled on a 5E3 circuit. Don’t really know why, perhaps it seemed straight forward enough. I was wanting something that would be interesting with more than 2 tubes. The schematics were available all over the internet, and good wiring diagrams to go with them. I had a transformer and a chassis from some other project. Sometimes you just acquire parts and heavens knows why.

Basic Chassis

Basic Chassis

This is the basic chassis that I had on hand and so it was to be used for this first project. At one point it had a transformer attached to it and this was going to be OK or so I thought. But at this time it was going to do the job.




Bag Of Parts

Bag of Parts

Took nearly a week to scrounge the parts, not all I used. many were unsuitable. I ended up purchasing other parts more suitable. Also shown is a wiring diagram that I added into a binder with other documentation.




Components Layout

Components Layout

I used a template to lay out the front but what I did not consider at the time was that I got the input jacks and the power controls swapped backwards.




Feaver 57 007

Initial Wiring

Not having a board but plenty of tag strip, I used this method for component mounting. Other amp examples have used this in the past but it is not efficient. The filter capacitor is on the right mounted in the underside. I did not feel like cutting a new hole for it. I will mount the cap properly on another project



Feaver 57 010

Completed Wiring

Well this was a rats nest. Certainly gave me lots of experience in what not to do again. Surprising that it worked as well as it did. This helped me to realize that no mater how weird it looked I could get it to work. But it’s not without it’s problems that I was later to find out.



Feaver 57 013

Bottom Plate

Nothing fancy here, some plate and feet on the bottom.





Feaver 57 012

Completed Amp

Completed Amp ready for testing and this was not without problems.




So how well did it work? First thing was that the interaction of the controls was not typical, they all interacted with one another that was a bit confusing. The volume worked in reverse. There was some ground loop in the way I had these set to earth. So I removed a ground line and things improved. The amp had lots of squeals, honks, motor boating and interference from local AM stations. So using a chopstick I poked around and began moving wires aside, some from the output transformer. This began to make a difference. I also found that some signal lines that crossed the circuitry caused interference and howling and when I moved them underneath the interference improved. Some source of hum disappeared as well. I also find that this amp plate voltages are a bit low, 270 to 290VDC and this makes for low output. However for my first amp, working with voltages way beyond what I am used to in normal amateur radio solid state electronics, I was quite happy to get my first tube project to operate. I finally had to give in and get a guitar to use as a proper input device at the right voltages and impedance that are necessary for this kind of work. So I got a Strat look alike called a Barracuda that does the job just fine. I am not a guitar player I am a trained drummer so this was a new angle for me. Now I have no excuse not to learn some guitar playing.



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