Developing the DIY "Champ" for first time builders

[RJ Guitars]

After years of working for a contractor to the US government, I have mastered the "over budget - behind schedule" song and dance... but I think the final product is looking quite good. I will say that although it is possible to build the simplest of amps for under $100, you'll make more $ per hour at Mcdonalds if you want to get paid for your labor. However, this project is about having fun and maybe learning something and that part of the equation still holds a lot of promise.

I shipped out the first few of many amp parts kits today... I prefer to call them "amp parts kits" rather than "amp kits" so that I leave DIY as a critical part of the process.

Thanks to the guys that helped me develop this idea into reality. Hopefully we'll see this continue to morph into other great ideas.

I'll post up a photo of one of my own prototypes of a "Premium" version that I put together just to make sure that the drawings were in touch with reality. I am going to leave the final build on this particular chassis to another builder... not that I don't "need" another amp or another project. I plan to save my myself for a "Supre" build which will likely involve a KT-88 output tube... bigger is better isn't it?

Thanks again, the fun will continue.

rj

[Cliff Schecht]

But predrilled chassis take out half the fun!

[Zippy]

Just wanted to give some evidence that although I'm asking for some handouts here and there, I am putting in some effort...btw, did I get that tube recto math right?

I think you overlooked the fact that we are omitting the tube rectifier to: 1) minimize parts count/cost, 2) increase reliability, and reduce PT demand.

There are no benefits to using a tube rectifier in this application.

[M Fowler]

Very nice rj, I am looking forward to some builds to give to my grand kids.

Got mini strats for them as well, lucky kids!

[RJ Guitars]

But predrilled chassis take out half the fun!

Yes and these were extra fun. I am not sure what alloy this is but it's bubble gumish just like the old BUD boxes. Not as friendly as the 5052 Aluminum that I've used the past few years. Cutting fluid helps and I also bought some of the first rate deburring tools that helped a bunch too.

The future of the low budget Champ will likely need to depend on a DIY chassis effort, but for the Eagle 100 I wanted to get a bunch of them the same so the results might be more comparable (and predictable) so I waived the chassis prep fees.

We'll see how they turn out, should be fun and realitively straight forward to put it together.

rj

[RJ Guitars]

Very nice rj, I am looking forward to some builds to give to my grand kids.

Got mini strats for them as well, lucky kids!

I love the mini Strat... now that is what I call a very cool Grandpa!

[xtian]

RJ, can you repost the latest schematic and parts layout?

[RJ Guitars]

I moved the schematics and layouts to page one to make it a little easier for everyone to find them.

I packed up the boxes for the all the combo builds this weekend and they will go out tomorrow. This concludes round one for the basic and the Premium versions.

After a day or two to rest, I'll finish up and post the drawings for the Premium and eventually, the Supre...

rj

[Firestorm]

On both the schematic and the layouts, you've got the values for R11 and R10 swapped (compared to the 5F1).

[RJ Guitars]

On both the schematic and the layouts, you've got the values for R11 and R10 swapped (compared to the 5F1).

I believe you are correct...

I edited the drawings and re-posted with correct values.

Thank you!

rj

[xtian]

I don't understand the need for the Cab vs. Head layout diagrams. Sure: tubes up versus tubes down...but it seems like either layout will work--the only important issue which orientation you apply the labels to the front and rear controls. One man's ceiling is another man's floor.

BUT, if you are sending a turret board with turrets attached, that determines which layout you can use, right? Because the board does not have bilateral symmetry.

[ToneMerc]

I don't understand the need for the Cab vs. Head layout diagrams. Sure: tubes up versus tubes down...but it seems like either layout will work--the only important issue which orientation you apply the labels to the front and rear controls. One man's ceiling is another man's floor.

BUT, if you are sending a turret board with turrets attached, that determines which layout you can use, right? Because the board does not have bilateral symmetry.

It matters trust me, I've made that mistake before. If it didn't you could just rotate the board on the same plane 180 degrees and the "symmetry" would be the same. It doesn't matter whether it's turrets or eyelets, the same condition exists. While just changing the labels from front to back corrects the outside appearance, it doesn't bring the same matching wire routing orientation with it.


TM

[angelodp]

As in pinout orientation. Looking from in the chassis toward the solder tabs or from under the chassis looking up at the tube. Pin numbers will run clock or anti-clock.

[RJ Guitars]

In practical terms it might have made more sense to just turn the amp over and have the controls on the opposite side of the amp... then all you need is a reversed faceplate and the amplifiers are identical. However, I have this weird thing about wanting the input on the left side of the amp whether it's a tubes up or tubes down layout. In order to accomplish this you mirror the layout - sorta. The tube sockets can't be mirrored unless somebody is making reverse order tubes and sockets etc.. It wasn't much trouble to make reverse image circuit boards so that part was easy enough. The wiring from the board to the sockets is just slightly different but the simplicity of this amp made it a great candidate for me to learn some lessons in reverse layout technology... hopefully I have it right. I appreciate the extra eyes reviewing the drawings.

rj

[M Fowler]

rj I with you I like my input on the left, non Marshall orientation, if you will.

Even if I decide to build another Marshall I want to do a reverse faceplate layout to put the input on the left. It really bugs me to have it the other way.

Talk about confusing, I'm building a tubes up Dumble 100w reversed from the layouts on TAG, it's challenging to say the least.

Mark