The Amp Garage

[RJ Guitars]

I've been interested in developing a way to consistently build an Express without the traditional pain of getting every wire in exactly the right place, tweaking and cursing. While on a long airplane flight I designed my own Express based layout and circuit board. I had been trading ideas back and forth and sharing designs with Mark Fowler for a couple years on this idea but time had not allowed me to get anything done. After I got to me destination overseas I ordered four prototype boards and when I returned, they were here waiting for me.

First - a digression about some of the recycled hardware I am using. I had this idea a while back that I would revisit the Trainwreck layout and move those transformers apart... seemed like a good idea at the time but it hummed like a Bumble Bee. I fought with it for a while but finally gave up and decided to just admit it wasn't going to work. I pulled the output tranny and head-phoned it around and found a half dozen places where the hum was minimal and one spot where it was zero (at the other end of the chassis). Funny, one of those minimal places was the traditional Trainwreck location. So I commenced to cutting out the top of the chassis and re-purposing it for yet another new idea. I made up a new top plate and fit it onto the chassis and began the efforts to create a simplified version...

I found three willing partners to build a prototype with my board and chassis and once that hardware arrives in their hands (this coming week for most of them) you may see some activity on this effort. I'll keep you up to date as I work on this project but I expect the other guys will be done before me... I am a bit too busy for anything but sharing the idea right now. Depending on the results, I'll make improvements on the boards and chassis and make more of them available.

Stay tuned, this could turn out to be entertaining...

rj

[guitarsnguns04]

Pretty cool concept rj....I'll keep my eyes on this ....curious to what the results will be....if you need another willing builder let me know. I'd be interested in giving it a go myself.

[Bob S]

Heresy...
I am very interested in this.
I would really like to build an Express or Liverpool without having to dink with them too much when initial assembly is complete.
When they are right they sound wonderful.
Getting there is a real PIA.
Good Luck with your worthwhile endeavors RJ & associates.

[guitarsnguns04]

Bobs...sounds like a natural progression that once the express is solved the Liverpool layout will probably next in this experiment....just a guess though. It would be nice to be able to build them consistently with a revised layout that keeps all the tone intact and reduces all the tweak time to get them quiet and stable. I'll be staying in tune with this thread.

[RJ Guitars]

I'll throw up a couple more photos that will add some perspective to this effort... some folks already had this part figured out. I'll say up front that I really don't know how well it is going to work but I wanted to develop a layout and circuit board that will add consistency to the results. The hope is that the results will ultimately be good not just consistent. That's why I asked for some help in putting these first prototypes together because I anticpate that it will be a challenge to conquer the beast. If we are successful the we will preserve the Express character and performance while reducing the build time, etc..

For those that are interested I was sorta thinking that we'd test the waters with the first four prototypes that are out there and then offer up more of them in a Gen-2 version. The bare bones package (Chassis, Transformers, and circuit board) is about $300 and that shouldn't change with the nest iteration. As you can see I've set these up with Edcor transformers and a standard sized Trainwreck chassis. I wanted to use non-traditional components to avoid the high dollar mojo tax since we've already broken most of the trainwreck rules anyway.

The front panel is standard Trainwreck specifications and I've added the IEC socket to the back but otherwise it's similar to the familiar Wreck controls.

Thanks for the interest.

rj

[UR12]

Here is one that does work. Like you, I have had this project on hold for about 4 years. The prototype you see in the pic works flawlessly and uses the traditional chassis layout. One recomendation I would give you is to go ahead and include the pots mounted on the PCB so that you eliminate wires runs to the pots. Don't want to side track your thread,. Just thought you might like a little input. I don't have any plans to offer this in a kit but it will probably become our production Express in the near future.

[Jana]

RJ,

In the first photo, is that orange thing on the chassis a new style of transformer? Does it give the push/pull, killer bee sounds for metal sounding amps? What's the bias current on something like that?

[dorrisant]

Is the bright switch disconnected, Dana?

[UR12]

[RJ Guitars]

[dorrisant]

Dana,
Did you build more than one, and if so do they sound the same? Just curious... Express builds are hard to make sound alike. With the pots mounted to the pcb, it seems you will repeat the harmonic content due to that wiring or the lack of it.

[RJ Guitars]

Thanks Dana UR12 for sharing your inside look on your PCB Express efforts - It looks like you have preserved a lot of the Express layout. I agree that focus on the "pots" is at the forefront in this effort. I find that the volume pot and associated "brite" electronics are very sensitive in the Express circuit and the Presence control can also be at the root of many Wreck issues.

I used this link as a starting guide for development of the board - http://www.geofex.com/article_folders/pt-to-pt/pt-to-pt.htm There are some tradeoffs that I can see in simplifying and minimizing amp lead lengths and it will be interesting to see what is required to untangle the good from the bad on a PCB layout.

thanks again,

rj

[UR12]

[M Fowler]

It's great seeing a couple of PCB designs and knowing Dana's works so well.

We will be putting the rj PCB Express to test soon.

I always had interest in JoeBob's Hoffman style board as well not sure if anyone ever built one?

Mark

[Richie]

I'll vouch for what Dana said. It was fun playing it, and sounded great. I was really suprised.
I figured others might feel the way i did. And the only way would be to play them,and then you could make your own judgment on them.