Attempted Simplification of the Express - Non Traditional

[RJ Guitars]

Always appreciative of supportive words - there are a lot of really good guys that hang out on this forum. I have learned a ton over these past few years from the contributions that everybody makes. It took me about 7 years of tube amp study and effort to finally make a decent sounding Express so none can accuse me of being a fast learner despite how much help you guys have given me.

I studied the pros and cons of the PCB board idea before I put this together and there were a couple cautions that I used for guidance. One was to avoid mounting the tubes directly to the PCB board. The primary reason was that you would be flexing the board with every tube change and also that you are applying a lot of heat to it... the obvious stuff that you guys mentioned above. Once I read that it made sense but I was pleased that somebody else wrote up an article to steer the way without having to learn everything the hard way. http://www.geofex.com/article_folders/p ... -to-pt.htm

Noise Issues? -- It is not noise free but nothing that seemed problematic or unexpected - plenty of hiss. I am expecting to have to do some tube rolling to really dial it in and minimize the noise. I am overall extremely pleased because there were no immediate glaring issues... I'm sure as I play with it I'll find opportunities to make some positive changes.

I set the bias at about 44MA on each tube and then got out the Les Paul. It really sounds great - reminds me a lot of a Marshall and is very fun to play with. At one point my wife came out to the shop and suggested that I should consider turning it down so that she didn't have to call the cops to save the neighbors the trouble.

It has a very nice clean sparkle to it and I think it sounds better clean and cranked than the traditional that I was working on last week, but that's a tough call since it wasn't a head to head comparison. I also don't necessarily have the ideal speaker cabinet for this circuit so we are going to reserve "awesome" and "perfect" in the event I am able to improve on how it sounds with tubes, tweaks, or speakers. Well worth doing and much less trouble than my attempts at other Express clones and hybrids.

We'll see how the other guys do on theirs so that we can get some perspective and objectivity on how easy it is to put together and how good it sounds.

rj

[eazilyled]

Great work RJ. Looks really tidy and +1 on keeping the sockets chassis mounted.

I'd love to build one of these down the line.

I know what you mean about volume. I find my unattenuated Express to be truly scary

[M Fowler]

rj great looking build and I like what you said about how well the amp is sounding that is a big positive.

I need to get started on mine, sorry buddy.

Mark

[RJ Guitars]

I played with the amp again tonight for another 15 or 20 minutes and it really sounds nice. I tried a 5751 tube in the V1 spot and it definitely sounds good. I did not notice any significant performance difference (loss of gain) but I think it does sound sweeter than the VOSKHOD 12AX7 I had in there before. I really like the way this amp sounds with the Les Paul.

I'll give you a better look at the brite cap layout I used. As you can see from the photo I rotated the volume pot around to minimize the lead lengths from the brite caps. I'm pleased with how this came out and I think it is an improvement over the longer leads that always seemed to be problematic on my previous Express builds.

rj

[HobbswheresCalvin]

that brite switch wiring looks really good. very clean. i am very tempted to wait for when you start offering the PCB boards to order parts for my next build, i like the look alot

[RJ Guitars]

Thanks Hobbs - I am pleased with it but I am trying to be cautious not to overstate how good this amp sounds since I have just not built that many Express amps and as near as I know maybe this one just sounds average. I am really pleased and I haven't even tried my best EL34's in it yet. I have really never succeeded at the clean to mean thing with any great satisfaction before. I am definitely a clone school dropout so it's very pleasing to me to get by with a departure from the standard parts selection... the parts cost is pretty reasonable for this build as well.

With this amp I feel like when I play something well it sounds so nice and then when I biff it she seems to scream "you suck"... she is merciless at pointing out my mistakes.

I have to get some more orders out and get my taxes done then I am planning on ordering up a dozen more boards for the TAG folks. I wanted to know what kind of results the other guys are going to get with the first iteration PCB boards before I decided whether to leave the board design alone or update it... I need to see at least one more success.

rj

[HobbswheresCalvin]

i totally get ya, i just took my amp over to a friends to show her how it sounds, we plugged her guitar into it, and it was night and day from mine. i spent ages working on finding the right set of pickups for my guitar and i think alot of the clean to meanness is in the guitar as well. i really didnt like her guitar thru the amp nearly as much as mine. it sounded way too dark even though she was in standard tuning and i was in Drop B. the crispness i get with my guitar and the amp is unbelievably different. and these amps definitely dont lie to you.

i rather like that though, it makes me play better, that way when tour comes around ill be able to put on the mask again and slay with the big boys in the tone arena.
im calling my clone Cocaine, cause she dont lie.

[dorrisant]

Great looking job, rj.
I love the wiring for the bright switch! Good idea rolling that pot around. Can't wait to get all the parts in and finish.
Btw... with an amp that is beautiful when you play beautiful and punishes you when you are not, I feel more compelled to play more. The risk/reward factor is a wonderful challenge and will tend to make me return to that same amp again and again.
Come on USPS/UPS!!!

[badtweed]

I finished her up today - I figure I had about 12 hours total in build time. For many of you it would probably be more like 8. I'm not especially fast at anything but especially prototype amp building. It was really fun and even though i was making up a lot of it as I went along, it went pretty smoothly - therefore quickly as well.

I think I created a better way to wire up the brite caps and keep the leads very short. FWIW - It will work on a traditional Express build as well.

I am using a new tube from Russia for the preamp tubes. They are VOSKHOD 12AX7's and super cheap from AES. For the power tubes I have a NOS set of SVETLANA EL34's from the 80's.

How does it sound? - Very Express like and quite good at that. I have not built a lot of these and only one that you could call a traditional format so I am no expert on the Express sound. I do think I would be very pleased with Geetarpicker at the controls... it seems like everything dials in nicely. Great clean to mean sound and as expected way louder than I can ever hope to use. It has more clean headroom than any previous Express I've built. This is the first one with all Edcor transformers so lots of new info being revealed here.

It looks great - I did slow down and tried to pay attention to the wiring and the soldering. I'll attach some photos and I like the results well enough I'll have to think hard before I alter that circuit board design. I grew to like it a bit more than I thought I would as I put it together although I'm still convinced it could be laid out better.

Enjoy.

rj

Looks very nice.
I really like the idea of quicker builds with repeatable sonic results.

I'd be interested to see if ghost notes are a problem or not.

Whenever I see pcb builds of this type my first concerns have to do with
ease of serviceability and reliability.

Looks like your build does not provide any major hurdles to getting inside and replacing components if required.

[Colossal]

Great looking job, rj.
I love the wiring for the bright switch! Good idea rolling that pot around.

+1! That is a slick idea.

Btw... with an amp that is beautiful when you play beautiful and punishes you when you are not, I feel more compelled to play more. The risk/reward factor is a wonderful challenge and will tend to make me return to that same amp again and again.

I agree. I was just talking to Mark Fowler the other day about the unforgiving and very honest nature of these amps. Once you get into them, they immediately show you where you need to improve your technique.

Come on USPS/UPS!!!

I'm looking forward to giving one of these a shot.

[M Fowler]

I'm working on an rj PCB Express right now getting everything under the board wired up and making sure all grounding points are tight. Next will be building the board.

I have a hard time playing an Express, I'm more Fender, Vox and Marshall oriented I guess. I had some guys over that knew nothing about the TW amps. I noticed one guy rolled his volume a lot so I plugged him into my Express and he sounded fantastic and could get such a nice tone out of the amp. I sucked, so I am not a fan at all of the LP or Express

Mark

[loctal]

Nice work RJ. Very elegant implementation of the volume pot and brite switch.

[ChrisM]

Who designed the PCB layout?

[RJ Guitars]

Who designed the PCB layout?

Chris, if you go to the opening entry on this thread you will see that I am guilty... it's a long convoluted story of learning a new layout software while enduring the effects of a long airplane flight, jetlag, ambien, and maybe a little Bailey's. I was delighted with it at the time and placed the order from over seas as soon as I got settled in to my room... the boards were here waiting for me when I got back and I recall the first time I really looked the boards over and saying to myself "what was I thinking"? As I put the amp together I did find I liked things a little more all the time though and the now the final results are really gratifying. Now I have to think about why some of that worked so well??

In all fairness, it isn't all new or unproven ideas for me. I had built a PCB mini Rocket before and made a half dozen prototype boards for Liverpool and Express amps that were very similar in layout. The power supply layout I used has been good to me in several designs previous to this one and the front and rear panel specifications are similar to most Trainwreck builds. I've been working up the Liverpool and Rocket versions since I finished this first Express and I am using the opportunity to clean up things a bit while I am at it.

rj

[M Fowler]

RJ,

Your PCB Express is a very nice design, I have been enjoying the build.
I did not get time or enery to work on it today, maybe tomorrow.

The first thing I did was make a visual reference of where everything is going and wrap my head around grounding points, etc.

I completely forgot about the 1k/25w resistor until I saw your metal cased one, so I copied you there, thanks bud! Also, I ran 1R resistors from pin 1-8 to ground tab under PCB. I was thinking about putting bias probe jacks on the back but then the 25k bias trimmer is on the board so didn't.

Not sure which caps I want to try in this amp, I have 6PS, 715, 716, old Mallory OD, M150, and Mojo Dijon which I like in some Marshalls I built.

Talk to you later rj,

Mark