JCM800 clone w/ mods!

[DrNomis_44]

Dr_Nomis, I love the plexiglass front of you amp. Home made definitely has more character...and people can tell when Ive made them!!

I've decided on a Jensen C12R for the speaker to go in the combo. I'm not really a fan of the Vintage 30 or Greenbacks...which is weird when I'm the right side of the pond!

That's actually a piece of clear perspex I found in amongst the stuff in my dad's workshop, it was lucky that it happened to be just wide enough to fit, all I had to do was cut it to length and drill some holes for the mounting screws, and then fit some suitable pieces of wood scrap to the cabinet.

Part of the fun of making home-made guitar amps is searching for suitable material to build the amp, most of the bits and pieces I scrounged while working in my dad's workshop, I did have to buy one expensive item though, which is the output transformer, if my memory serves me right I think it cost me something like $380.00, or thereabouts, and then when it came to the power transformer I didn't know where I could buy a suitable one, so I found a power transformer that came out of an old reel-to-reel tape recorder, it looked like it was about the right size, so I proceeded to strip it right down to the cardboard bobbin, next I measured the dimensions of the transformer's core, and then did some calculations using a book called "Build Your Own Coils And Transformers", and then re-wound both the primary and secondary windings of the transformer according to my calculations, the transformer actually worked first go.

This time round, I'm going to go ahead and buy a proper, commercially made power transformer.

[Marcel]

Yep... Without the proper machinery the whole winding transformers thing is a mugs game... and these days after many barely passable attempts I'd much rather pay someone who has the right materials and machines to do it, and let them do it right...

[Ik7]

Funnily enough I bought a transformer book from Australia on how to wind your own power, output and choke transformers. One day I'll have the nads to wind my own transformers, so I commend you on that!

I had an idea for using perspex and drilling a couple of small holes on the end and putting LEDs in to get a nice back glow.

I am loving toroidal transformers at the moment, if I could find an output one for the right price I'd use it.

[Marcel]

Many many many many many moons ago, when toroidal transformers first came on the market, a few intrepid builders tried making toroidal output transformers... and although they are better at efficiency and they cost about the same to wind, the whole idea never really took off as the 'puritans' amongst us complained that they "don't sound right"...

Technically it makes sense... at 50Hz or 60Hz the current make up of the ferric former of the toroid is ideal, but the same former for wideband audio use is not as it has different responses at different frequencies... find the right former with a ferric (or some other) make up that gives an acoustically appealing response and you'll be on a winner.... There are dozens of former types to choose from... Good Luck !!

[DrNomis_44]

I actually had to re-wind the transformer all by hand, to say that it was tedious is an understatement, the very first time I re-wound it I ended up having to completely strip it down to the bare bobbin and start again because when I put the laminations back in I accidentally cut one of the primary windings with one of the laminations, eventually I succeeded and had a working power transformer.


Because a Toroidal transformer has a core shaped like a ring, the magnetic field is shaped differently compared to a conventional transformer, the magnetic field is more contained, the benefits of that is lower induced hum-noise.