Attempted Simplification of the Express - Non Traditional

[RJ Guitars]

Awesome Colossal Build - Thank you for your touch on this project!

[dorrisant]

Dave... you say that is not "show"quality... I for one beg to differ. Looks beautiful!

I'm waiting for parts to implement the filament scaling. In the meantime, I did rewire the tone stack. Well worth the effort... much more harmonic content.

The rumbling noise seems to have stopped for the moment... but I won't hold my breath yet.

I have to agree... overall, it was a quick build. The first time I tried it, she fired right up and sang. All of the voltages seem to be in the right ballpark. The amp didn't develop any noise until after it had been burned in for a while and I think the problem is due to a bad component. I will get past this and a few mods and it will become a permanent resident next to my Rockster builds.

Tony

[fishy]

Tony

I did rewire the tone stack. Well worth the effort... much more harmonic content.

Do you have a before and after image of the rewire. I would be interested to see the difference in lead dress. It strikes me that most do not consider playing with the lead dress around the tonestack and are more prone to look towards plate and grid wires etc.

[martin manning]

I wanted the extra couple of switches to see how the amp reacts to lower voltages (maybe a little browner sounding?) and see how the different OT primaries sound. I like a bit more aggressive tone so want to hear the difference between 5k2 and 6k6 first hand.

How's this stuff working and what are the tonal differences? Do you have any definite preference for one voltage or Zpri over the other? On the bass content, I had the thought that you could try increasing the 10k resistor in the presonance circuit to 5k, which would perhaps shift the response up a bit.

[Zippy]

Awesome Colossal Build - Thank you for your touch on this project!

Seems like some sweet PROTOTYPE builds - when is the next set of boards coming out? Ready to call it "production"?

[Colossal]

How's this stuff working and what are the tonal differences? Do you have any definite preference for one voltage or Zpri over the other? On the bass content, I had the thought that you could try increasing the 10k resistor in the presonance circuit to 5k, which would perhaps shift the response up a bit.

Hi Martin,

I did get a bit more time today with the amp. I left it idling last night for a while to break it in, form the caps and such (love that new amp smell). As far as Zpri goes, I think the 6k6 tap sounds best to me. I think the harmonic content and depth is slightly improved and more of the hallmark Trainwreck 3D almost-built-in-reverb quality comes out a bit more than on the 5k2 side. The 5k2 primary sounded good, but perhaps just a little flat for lack of a better word. I just kept playing similar riffs and big, wide interval chords and switching back and forth. This was done on the 300V side.

The low end is thicker all around on the Express and I'm convinced that this is intrinsic to the EL34s and not just brute power. I am hearing the horn-like, musical, and rather elastic power supply compression. This quality is really noticeable with my Liverpool variant and I love the way that amp sounds. Both of these amps sound really similar, the major difference in feel (and low end) seems to be in the power tubes, not so much the overall tone. The Express feels just slightly "later" than my Liverpool and I think it is bias excursion and recovery. My modded Liverpool seems to have a more 3D, almost like a plate reverb with more midrange content and it's got to be that EL84 swirl. I am basically setting up both amps in the same manner and A/Bing. Even though, on its own, my Liverpool has quite a nice, tight low end whump, it sounds almost anemic in comparison with the Express. For me on both amps, I like the grid leaks somewhat lower than 220k (using a PPIMV) as this seems to add a bit more PI crunch (which I really like).

With this Express, I think the next step for me would be to see about tightening the low end a bit. It feels very much like a 50W Plexi feels (which of course is excellent) where the note hits and you feel that you arrive comfortably late and in style, not hard and glassy with the notes dying under your hands as some (unpleasant) amps do. But the clarity and feel on my Liverpool on the low strings is phenomenal (I'm using a 7 string) and I feel it edges out the Express slightly. This is not a criticism in any way as the differences in feel are very, very subtle. I would like to get that same degree of clarity with this Express. I think targeting that second stage bypass cap might be the place to start. Maybe 0.68 to 2.2uF? I don't think the coupling caps are too big. The amp seems perfectly balanced really, just needs a bit more clarity (perhaps I'm using clarity synonymously with midrange?) and a bit less 'woof'. What do you think?

Keep in mind too that I am playing prog rock/metal, not classic rock. The tone in my head is Alex-Lifeson-meets-Van-Halen-meets-Tool and that's what I'm after. I want to be able to play very wide interval chords (1-5-9, add9, sus2, etc) under heavy shimmering distortion but hear every note. For me the Trainwreck spring-like compression is absolutely essential. This is the closest I've gotten to that tone in my head. I like low output pickups as I want that early Van Halen warmth and clarity that is clean but dirty at the same time.

[Reeltarded]

Exciting!

Question, Mr Dave? Did you add the Faraday stuff as a tweak, or just from experience from before? I wonder how much of something good I am losing in my mods from using 10' of shielded wire instead of creating an alternate universe for the noise.

[Lindz]

Following this thread with interest..

Colossal, what gain mods did you do on your Liverpool?

[Colossal]

Exciting!

Question, Mr Dave? Did you add the Faraday stuff as a tweak, or just from experience from before? I wonder how much of something good I am losing in my mods from using 10' of shielded wire instead of creating an alternate universe for the noise.

The faraday coil was mostly a tweak. I have been at odds with shielded wire of late. Having been messing around with the Trainwreck circuit for a while now, it's been a bit of an epiphany in that you hear how much every little thing makes an audible difference in the tone and the amp's response. On my Liverpool, the input tube is right up front, so the grid wire is about 1.5" long. I had shielded wire on it originally but I don't like how the inner strands are so very tiny. I think they fatigue incredibly easy. I was using Belden shielded which is ok I suppose. I originally bought it for use with PPIMV runs but honestly I don't find that shielded wire is all that necessary in that application. So with the Wreck I wanted to use hookup wire only, mostly as a hedge against anything potentially messing with the tone, good or bad. I also was having a bit of fun with the PCB amp and I was able to just focus on building the amp for fun (instead of a client) and just thought it would be cool. Nothing more really. I used a long shaft screwdriver (haha, I said long shaft) and Belden 18g teflon/tinned wire for the coil. I use that stuff for heaters and it stays put. I wanted to make the coils tight and they are.

Following this thread with interest..

Colossal, what gain mods did you do on your Liverpool?

Lindz, there are a few things, not really one 'mod' per se. As I've stated, my goal is a pretty modern melodic prog metal tone. I always describe my tone as a fusion of Rush, Van Halen, and Tool; that's what I'm after. So, I'd characterize that as a lot of grind that is just grind, no fizz/spray or buzz like you get with a Boogie or an Engl for example (no offense to them). First, I'm using slightly higher preamp voltages and slightly higher filtering in the preamp. This made the most difference fundamentally. I've also set the PPIMV to a max of about 163k. I play from moderately loud to quite loud. The lower grid leak values that the PPIMV provides, depending on setting, pushes the phase inverter more and gives a little more midrange crunch (plus the amp is so ungodly loud when cranked). I also run the tone stack almost wide open, especially the treble as this passes more signal to push the second stage a little harder. Most guys are running the Volume and TMB about 1 o'clock. I found that to be no where near enough for what I wanted. I'm running the Volume around 8. Lately I've been liking the bright switch where before I was running it off. I also added a Cut control and although that's not related to gain, it does take the upper edge off just a bit which I find very useful. I also used a different OT than the stock Liverpool 6k6 primary. My amp is biased to around 11W per tube. Originally I had a single cathode resistor but recently rewired to two separate resistors as per the stock layout. I also have been messing with the 10k clipping stage, that is spot to tweak. Lowering that value will increase gain. I like the grid leak on the third stage at 150k, going higher did not result in any improvement. I did not change any of the plate resistors as I do not want to change the amp's fundamental tone. Ken Fischer got it right and I'm not screwing with that. My goal is to make the amp just a bit meaner, just a little more midrange character and crunch. Ultimately I want the clarity, harmonic richness and that almost 3D depth. The amp has that in spades, I just needed to personalize a bit. Preamp tubes play a big role in that so roll some to find what works for you. Finally, and not to be coy, I did a couple of other small things which I will keep to myself for now as I'm not quite through playing with them yet. I hope that helps.

I know some of this might be looked down upon as sacrilege and heresy but I think it honors Ken's memory to continue his legacy by building his design. I don't think he would have been one to rest on his laurels and would encourage pushing the envelope. The more I study this design, the more appreciation I have for the guy. The whole power supply design coupled with the preamp configured with decreasing gain as you progress is a master stroke. The amp is incredibly musical sounding to me.

[Colossal]

Dave... you say that is not "show"quality... I for one beg to differ. Looks beautiful!

Thanks a lot Tony, very kind of you!

Best,
Dave

[dorrisant]

Tony

I did rewire the tone stack. Well worth the effort... much more harmonic content.

Do you have a before and after image of the rewire. I would be interested to see the difference in lead dress. It strikes me that most do not consider playing with the lead dress around the tonestack and are more prone to look towards plate and grid wires etc.

I think you can see a bit of the old wiring on page 6... I didn't take any good shots of that configuration... I didn't think it was noteworthy at the time. I will post some of the new when I get a chance.

The routing was basically the same. The wire is much different. The old was 20ga stranded copper pvc coated. The new is 18ga solid pvc coated. The old was stuck to the chassis with spots of silicone. It was also routed with barely any space between the runs. I knew I could get the amp stable with this wiring. I found the newer wire hiding in my shop and swapped it out.

Dave... I love the Faraday coil implementation!

I'm gonna try out some mods soon. I just wanted to work at one thing at a time.

The amp was pretty quiet last night... played 3-4 hours without any noise.

I was playing a baritone tuned down to drop C... with the gain on 9 and the guitar vol way down for clean. It sounded very piano-like! I realized this is probably why the clean tones sound good to me. Not that I play piano... just the familiarity feels good!

Tony

[Zippy]

I know some of this might be looked down upon as sacrilege and heresy but I think it honors Ken's memory to continue his legacy by building his design. I don't think he would have been one to rest on his laurels and would encourage pushing the envelope. The more I study this design, the more appreciation I have for the guy. The whole power supply design coupled with the preamp configured with decreasing gain as you progress is a master stroke. The amp is incredibly musical sounding to me.

Progress in the forward direction! <applause>

Respect to you, Dave, and RJ for keeping the fires burning. Of all the contributions at The Amp Garage (including the Dumble forum), this is among the most creative work I've seen in a while.

Hey, RJ, what's up with the next iteration of this project? Where're the boards? What's new with you? Version 1.3 or 2.0???

[ampdoc1]

These are some great builds! But I wonder if you're over thinking the "problem" of the layout. I've built four "variations" of the Express in various donor chassis, with different orientations (usually close to stock of the chassis) of the preamp, power supply and transformers. I've had no problems with hum or oscillations in any of them. Sure, the hiss can get pretty bad, but I've compensated by putting in different 12AX* tube combination's chosen to maximize the sound vs the hiss.

I don't use any special techniques other than neat wiring practices, and they all get that Express "touch sensitivity" and feel..

a'doc1

[RJ Guitars]

I was really pleased with the Colossal finish to the four prototypes of this amp. All four of them have gone together with minimal trouble... I really expected a much greater challenge.

At this point I am ready to move on and make a few "improvements" to the board. Is there enough interest to merit a dozen of the next rev of the boards? If not, I'll have a few made up with thoughts of building a half power Liverpool. The new board will support either amp circuit.

It's my plan to offer them to the TAG crew exclusively and again as prototype efforts. I will be selling bare bones packages consisting of a PCB board, chassis, and transformers. I really liked the varied parts selection used in these first four so no full parts package is in the works yet. There are too many good options to explore before I try to lock down any one cap and resistor parts selection.

Let me know if you are interested and I'll order the boards as soon as it's clear the interest is there.

rj

[Decko]

Hi RJ,

Count me in!

BTW: How did those EL34's East German makes work out?

Danny