Attempted Simplification of the Express - Non Traditional

[RevD]

I love the way this thing is layed out. I was going to put an express together, heck now, I'll wait until this is in production, by that time I'll have my finances to do it right.

Good Job RJ, anxious to see how the proto-types turn out and sound, should be really cool, I'm a Marshall kinda guy so this just may be what I'm looking for. I suspect you'll be selling a lot of these guys!

Regards,

Don

[RJ Guitars]

Thanks Rev, This is the first amp I've put together for a while that has kept me from working, it has been really fun to play thru.

I finished up the next PCB board design iteration last night and it can go into production anytime. I did want to get the feedback from the other three of these that are in progress before I pressed play. I was thinking about a dozen for what will be formally called Rev-1.... humm that would be really funny if I had started with letters rather than numbers. Anyway - a dozen is certainly enough to prove an idea and still not wait too long to improve it. As far as I know now this ought to be enough to cover everybody that has indicated they want to play along... I think I have 3 names on the yes list and three more on the maybe list...

Cautionary note - consider it a prototype development effort, you will need to provide a "Reduced Expectation" release form to participate. Many amp builders and those in close proximity to them have experienced various side effects including nausea and vomiting when subjected to the results of prototype amp building... etc.

[dorrisant]

Just curious... how hard would it be to add the Presonance mod to the new boards?

I was thinking of adding a few turrets to accommodate this mod...

What do you guys think?

Tony

[RJ Guitars]

Tony,

that is a very good addition to include. I had previously contacted Martin Manning and he gave us his blessing to add that to the options so we have a green light. If you have an idea you would want to include on the next board iteration, it should be easy and timely to add it before this next order goes out.

rj

[dorrisant]

There is a little space on the PCB where the "rj-pcb-x" and version numbers are...
I don't mean to cover up rj's signature, but it seems like a convenient spot for the Presonance parts... close enough to the pot anyway...

My parts came in yesterday but I got the wrong octal sockets. I placed an order for the correct ones from tubedepot... I use them when I need something fast. Parts from them usually arrive before it clears the bank. I have everything else though, so not too much longer now.

Tony

[martin manning]

Tony, you have the latest version of the presonance circuit, right? One more resistor to find a place for. It'll be great to have another evaluation of it too.

[M Fowler]

Next time I would like to try using chassis bolted PCB type sockets to see if wiring them would be easier. I haven't had any trouble really but just thinking out loud.

I think there would also be room to add solder pads for the screen resistors as well. See picture note 1k5w white resistors.

[ChrisM]

Radial caps might be a good idea.
- much cheaper then axial
- more choices available (read more options while being cheaper too!)
- better specs generally (lifespan, ESR, etc)
- smaller footprint

If you went with radial you could reduce the PCB size and put the filter caps right at their voltage supply nodes. This is ideal as it decreases the B+ and ground runs. Should result to lower noise overall.

The way the PCB is designed now it just seems like a turret/eyelet layout but on a PCB board. I think one of the huge advantages to PCB is that you can optimize your layout, create a smaller footprint, improve consistency and improve performance. I'm not sure if that's all being done here.

This is not a knock at you RJ, just thinking out loud.
I just think the PCB could be smaller and improved a bit.

[M Fowler]

Yeah if a guy went two sided we could reduce the foot print even more.

The use of pots soldered directly to the PCB and tube sockets direct to the PCB would make this one fast to put together amp and improve noise at the same time.

But this is just V1 and rj can decide if he wants to go that route.

Mark

[dorrisant]

Tony, you have the latest version of the presonance circuit, right? One more resistor to find a place for. It'll be great to have another evaluation of it too.

Martin, I downloaded the latest and greatest earlier. I would love to implement and post results. Glad to.

Take a look and see if this will work... I want to be sure before I drill.

Does anyone see any issues?

Tony

[Colossal]

Tony,

I plan to do this very mod myself when my PCExpress board gets here. Should be next week (thanks RJ) Looking forward to the build.

[dorrisant]

Tony,

I plan to do this very mod myself when my PCExpress board gets here. Should be next week (thanks RJ) Looking forward to the build.

Does the above look right?

[Colossal]

Does the above look right?

Yeah man, that checks out to the schematic. Nicely done.

[dorrisant]

Does the above look right?

Yeah man, that checks out to the schematic. Nicely done.

Right on!

Putting it in tomorrow...

[martin manning]

On the presonance mod layout, the pot needs to be replaced with a 10k audio taper, and the outer lugs need to be switched- the clockwise lug goes to ground. And of course the existing presence cap that is hanging on the pot should be removed.