Reverse Image Wreck Combo Cabinet Design

[RJ Guitars]

Hello TAG folks,

A few months back communications with the machine shop went south and for one batch of chassis they read the drawings as looking into the chassis rather than at the top of it. After years of working with the same guys and creating hundreds of chassis, I dunno how that could happen???

I had them cut the top out of most of them and this allowed me to turn them upside down and plate them, creating some modular chassis... that works out in a good way so it wasn't a total disaster. However for a few other chassis I went ahead and made some reverse image chassis'. I had always hesitated to this because it means drawing up entirely new drawings, layout, and debugging. I recall that Dana Hall made a couple Wreck combos he was very happy with I occasionally get a request for them myself. So now it's begun... A couple guys are building the prototype amps, I'm about 2/3's done with the layout on a Reverb Rocket/Rockster, and I designed and had a few combo cabinets built.

However, although I am a decent capitalist, I really don't want to get too deep in the cabinet business. We have a lot of great cab builders here on the forum and they have the tools, skills, and love for the craft that I don't. I wanted to post up my cab designs and let the builders here have the option of furnishing the cabinets when I get a request for a Reverse Image combo package.

My cab builder is awesome but by the time I have cabs sent to me and then charge again for shipping them it adds a bunch to the cost. It's not too bad for a head cab but double shipping a combo cab can add $75 to my price. Aside from that, I appreciate the good folks here at TAG and I know they love to add to the personal touch of each of our custom builds.

Enjoy and feel free to use the drawings... sorry, the image doesn't transfer out of CAD to look good in a small footprint. You'll be able to see all the lines and such when you expand it a little bit.

rj

[M Fowler]

I like the cabs rj and a Rocket combo is always a good amp to have.

[Jana]

I'm confused. How does a reversed chassis affect the cabinet?

As for a reversed chassis, if everything is built in mirror image of the non-reversed, it should be fine. Unless, of course, there is something related to the rotation of the earth and the magnetic fields--but that gets us into the "red wire has better tone" argument and we know how those usually turn out.

[njwrecks]

Nice looking cabinets RJ- is that poplar? I am making one now using poplar.

[RJ Guitars]

I'm confused. How does a reversed chassis affect the cabinet? ...

In that typical Wreck format, the tubes are pointed up... so you could turn it over and have tubes down but then the faceplate is reversed. That is the simple way to build a Wreck combo but somehow it just seems wrong to have the front panel reversed... and I couldn't past that for reasons far too complicated for me to understand them myself much less explain.

When you mirror image the layout drawing a very interesting thing happens... the tubes are no longer going from pin 1-9 in a clockwise orientation but rather counter clockwise. The tube sockets don't accommodate that and it requires a new layout scheme, not too different from the first but just enough to take a little thinking about it. Also I have to create a mirror image circuit board setwhich is trivial enough to do but nothing I already have built works in the reversed amp.

Finally, on my most recent chassis I added a fourth preamp tube for a reverb driver so it becomes an amp that I have never built or debugged thus far.

A little bit of "Rocket Science" but not really anything like "Brain Surgery".

rj

[Jana]

Thanks for the explanation, RJ. It does make sense when I think about it: I am so used to the layout of a Marshall or Fender (pre-amp on the left when looking into the chassis and facing the knobs), that if I tried to build the opposite way, it would be really weird. It's interesting that the normal trainwreck layout is the opposite direction than marshall or fender.

[Cliff Schecht]

I've built them both ways. Pretty much as RJ says, the sockets are backwards and there's a few headscratchers you might have to solve. But I honestly don't notice or care after the build is done, but that's probably because I'm doing one-off stuff not production runs.

[RJ Guitars]

I've built them both ways. Pretty much as RJ says, the sockets are backwards and there's a few headscratchers you might have to solve. But I honestly don't notice or care after the build is done, but that's probably because I'm doing one-off stuff not production runs.

Hey Cliff, good to see you hanging around these parts with us... we can stand to learn a few things from you. Once you've made one good amp, you've done the hard part of getting the big mistakes out of the way to build a few more of them... I think accurate layouts are among the best indicators that you're finished with a new amp design... I am getting closer to getting the initial draft done for this particular effort.

[Jana]

http://www.youtube.com/watch?v=THNPmhBl-8I

[M Fowler]

I've built a lot of Rockets both EL84 and octal versions as well as reversed layout and it is challenging.

The board and faceplate is reversed but the tube socket pins are not so I've made some wiring errors that I had to change while building. Nothing hard but does require my brain to have to function on that particular day and that isn't always easy for me.

Oh Jana you really are being quite testy this month.

[Jana]

Mark,
Yes, this long winter has released my inner beach.

It's supposed to get up to 40 this weekend. I don't know how I will handle the heatwave--maybe put the A/C in the window?

I would wear shorts but the reflection off my legs could cause eye damage.

[M Fowler]

I hear you Jana. Fluorescent legs can blind my brother-in-law is testament to that. He does get a nice farmers tan in the summer though.

I heard 33 degrees tomorrow and and Sunday, I'm hoping it's true.

[Jana]

Me too hoping it's true. I am so tired of this winter. I put on 25 pounds, which wasn't a bad thing overall since I lost so much weight last year with some other stuff that was going on. But, I am ready for outside activities (that don't include 27 layers of clothes).