Attempted Simplification of the Express - Non Traditional

[RJ Guitars]

Thanks Mark,

Great to hear that you are recovering... modern medicine is amazing but you are wise to take it easy and do your part in taking care of your health.

I didn't want to send out caps or resistors with those first few build packages because I really wanted folks to choose their favorites and compare results. I am very hopeful that this layout will allow folks to use affordable parts and have a good result. Between the transformers and the filter caps you can cut the price over $100 from a traditional build so you can choose about any coupling caps and still not break the bank. I did use the old Cornell Dublier PVC caps on mine but I'll need to be convinced before I say they are the magic stuff. This amp reminds me a lot of a good sounding Marshall and the I think the Sozos sound really good in them so i expect there are several good choices.

My 1 Ohm bias measurement resistors were an after thought because I didn't think about them before I had the PCB board in place. I just got lucky that I could make them look decent where I finally put them. I need to think about using a remote bias pot so that you could measure and set the bias from the outside... that is a good idea for future revs.

I Actually had to scratch my head a bit on that 1K power resistor but I finally recalled that when I was laying this out I was going to use a chassis mount. Lucky enough I had one here and made it work. The holes on them will take a 6-32 tap and that can make the mounting job a little easier. I used to be skeptical about the need for that 25 watts of power capacity but on the last two Express builds I've done I've really pushed them hard with an Air-Brake on the amp and that puppy can get pretty hot. All the more reason to go with the chassis mount so it works out pretty well.

Looking forward to your touch on this build. Hopefully Colossal will have his on Monday or Tuesday and show us how it's done. Tony D. has the other one and he has gone into radio silence so I figure he is sucking solder fumes somewhere at the moment. For the guys that want on the short list to put together rev 2, lemme know. I think if I was thoughtful about it I could make the Express and the Liverpool to use the same board so rev 2 could be an EL84 amp as well. It would be way simple to choose between either cathode or fixed bias.

[Cliff Schecht]

RJ I've built a few Express's with PIO caps and could try the same thing with your boards if you'd like. I don't play my Express much anymore but I've got a really good idea of how it should sound and could compare it to how yours sounds with the same-ish components.

[surfsup]

RJ nice idea on the bright switch. I did the same thing last year on that X10 clone you got me the edcor PT/OT/chokes for. I don't seem to have any bright cap issues either although this is a liverpool type of design with the tone stack after the second stage instead of the first.

First photo here. (this photo was before I redid the bright cap leads and shortened them).

https://tubeamparchive.com/viewtopic.php?t=14565

Your layout looks very nice. Congrats on a successful first attempt! That's gotta be a good feeling!

[Zippy]

RJ nice idea on the bright switch. I did the same thing last year on that X10 clone you got me the edcor PT/OT/chokes for. I don't seem to have any bright cap issues either although this is a liverpool type of design with the tone stack after the second stage instead of the first.

The Express and Liverpool have similar topology with the tone stack after the first gain stage - it's the Rocket that has the tone stack after the second gain stage (and cathode follower).

[dorrisant]

Tony D. has the other one and he has gone into radio silence so I figure he is sucking solder fumes somewhere at the moment.

Funny you should mention that... I was sucking solder yesterday. Would have been better if it were just fumes. I had to pull the 1k 25w out and reorient the bias pot... still waiting for parts. I did get in some Jupiter Vintage caps. I have not tried them yet, so we will see.

As regards the radio silence... being a two-way radio tech demands a lot this year. Everyone with a two-way has to be on narrow band by the end of the year, so I'm working more overtime than I care for right now... could be worse I suppose.
Good luck with the builds guys, and thank you again rj for getting us in on this sweet project.
Radio service clear... um... oh well, you guys get it.

Tony

[M Fowler]

Here is my attempt at this kit.

[dorrisant]

Here is my attempt at this kit.

Attempt? ... looks like success!
Very nice, Mark.

[Zippy]

I like what I'm seeing - especially the lead dress in the chassis and the distributed power supply caps on the board. Clean!

How's the noise level?

[dorrisant]

Double post.

[Colossal]

Looks great Mark! Save room for mods!

[Tillydog]

Here is my attempt at this kit.

Neat job!

Those valves/tubes look like they've lost vacuum (gettering has gone white) - Is it an optical illusion?

Andy

[Reeltarded]

omg look at the face plate he's going to scare us with this one! Looks great all around. Very cool layout..

[cbass]

Here is my attempt at this kit.

Neat job!

Those valves/tubes look like they've lost vacuum (gettering has gone white) - Is it an optical illusion?

Andy

Looks like the nipples are broke off too.Mmmmmmm.... nipples

[M Fowler]

Thanks guys, I hope to finish wiring tomorrow and fire it up.

Those preamp tubes are old blown tubes I use when soldering the preamp tube sockets

If you have ever overflowed a preamp tube socket you learn fast to keep those bad tubes for your next build.

Mark

[Gaz]

Thanks guys, I hope to finish wiring tomorrow and fire it up.

Those preamp tubes are old blown tubes I use when soldering the preamp tube sockets

If you have ever overflowed a preamp tube socket you learn fast to keep those bad tubes for your next build.

Mark

+1 I've ruined a few Beltons that way!