Who's running grid stoppers?

[leadfootdriver]

Kens Express design doesn't have one. But, I'd like to avoid the inevitable Spinal Tap moment. You should probably at least get one on V1a.

What value are you running, and did you notice a difference in tone?

[Colossal]

I'm running 825R metal film at the input grid to V2a on a Liverpool. I play with a lot of gain and 7 string guitars so want to avoid blocking distortion (with that low B string) as well as oscillation. The resistor is transparent tonally and I have no oscillation with or without the resistor. I left it in for good practice. Ken notes 820R-2k2 as a tweaking value in that position.

Your new build is badass Leadfoot.

[leadfootdriver]

Cool. I play a 7-string as well, so I'm glad your amps are holding up to the task.

Thanks for the compliments!

[Colossal]

Cool. I play a 7-string as well, so I'm glad your amps are holding up to the task.

Thanks for the compliments!

+1 on 7-strings The trick to tight, defined, mean distortion is small value coupling caps and grid resistors. I've got plenty of low end in my Liverpool and the grind is glorious. The power supply has that incredible spongey feel but still stays tight with those low strings. Fat sustain too. I can't wait to build an Express.

[leadfootdriver]

Awesome. I always wanted an EL34 amp, but was never satisfied with the few Marshall's that I've tried.

I hope the Express is the amp I have in my head. I still need to get transformers tho!

[Colossal]

Awesome. I always wanted an EL34 amp, but was never satisfied with the few Marshall's that I've tried.

I've always loved Marshalls. Superleads in the hands of Van Halen and Jimmy Page are THE sound. Some of the lesser played Van Halen tunes such as Me Wise Magic and Little Guitars really show the magic in that circuit (not to mention the prowess of EVH's playing). Neither Page nor Van Halen's tones however are really considered high-gain by today's standards. But a cranked Marshall is definitely something everyone should get to experience. I do agree with you though. For what comes out when I play, I always want a little something more than the stock Marshall circuit.

I hope the Express is the amp I have in my head. I still need to get transformers tho!

Having built a Trainwreck circuit, I can definitely hear and feel what Ken F. meant when he said that a Wreck picks up where a JCM800 leaves off (I think that is KF quote, perhaps I'm mistaken). The way each of the gain stages is configured and where output tube distortion occurs first in the power section and works backwards is the master stroke. The tone stack late in the Marshall design cuts a good bit of signal out where the Trainwreck gets the tone shaping out of the way on the first stage. There is sufficient signal to push the PI and in turn push the output section. Fantastic sustain and a very pure grind when the gain is pushed. It stays very tight in my experience (I did take a few liberties however so my test build is not stock).

[rooster]

I have used a value as high as 22K on occasion. No, not every build needs it but this is all about the quality of that Tungsram V1, IMO. If you are not using a Tungsram, I imagine YMMV.

[leadfootdriver]

Awesome. I always wanted an EL34 amp, but was never satisfied with the few Marshall's that I've tried.

I've always loved Marshalls. Superleads in the hands of Van Halen and Jimmy Page are THE sound. Some of the lesser played Van Halen tunes such as Me Wise Magic and Little Guitars really show the magic in that circuit (not to mention the prowess of EVH's playing). Neither Page nor Van Halen's tones however are really considered high-gain by today's standards. But a cranked Marshall is definitely something everyone should get to experience. I do agree with you though. For what comes out when I play, I always want a little something more than the stock Marshall circuit.

I hope the Express is the amp I have in my head. I still need to get transformers tho!

Having built a Trainwreck circuit, I can definitely hear and feel what Ken F. meant when he said that a Wreck picks up where a JCM800 leaves off (I think that is KF quote, perhaps I'm mistaken). The way each of the gain stages is configured and where output tube distortion occurs first in the power section and works backwards is the master stroke. The tone stack late in the Marshall design cuts a good bit of signal out where the Trainwreck gets the tone shaping out of the way on the first stage. There is sufficient signal to push the PI and in turn push the output section. Fantastic sustain and a very pure grind when the gain is pushed. It stays very tight in my experience (I did take a few liberties however so my test build is not stock).

I came up on solid state amps, so I've always been use' to a fast attack. The 1st time I tried a Marshall, the attack was so low to me that it was like a delayed response. Having the tonestack latter in the circuit driven by the cathode follower is part of the reason I suppose. This is what I've always hated about Marshalls; the soggy attack and feel. They sound good, but the feel is not my style.

I did an Express like circuit in my little single ended test amp with a Vox tonestack, but the 2 fully bypassed gain stages are a bit to much for a single EL84 I think. I tried a Komet/Marshall type 1st gain stage with the parts I had on hand by running a 2.2k/.68uf 1st stage, and it cleaned up the bloated overdrive sound I was getting a lot. But the amp sounds more Fender/Voxy when I overdrive the tone. However, it's a great practice amp because it's real dynamic and revealing because it doesn't have a truckload of distortion and compression to hide the slop.

That said, I hope the Express has a rippin' distortion tone. I've seen kuykendalls' vids, and they sound good, so I'm confident that I'll like it. But I could always go with Komet 1st stage if I find it to fat.

[leadfootdriver]

I have used a value as high as 22K on occasion. No, not every build needs it but this is all about the quality of that Tungsram V1, IMO. If you are not using a Tungsram, I imagine YMMV.

I have an extra 10k I was planning to use.

[Colossal]

I have an extra 10k I was planning to use.

Are planning to add an input grid resistor to V1a? The grid resistor I was referring to is the sometimes-used mod Ken did to the entrance to V1b. Schematics note 820R to 2k2 in this position. Presumably, this is used to tame unruly amps or for a bit of tonal flavor. I used 825R (precision metal film) simply because I am concerned about blocking distortion using 7-string guitars with the two fully bypassed stages in the Trainwreck design.

That said, I have very clean, articulate distortion with plenty of low end. I think however Trainwreck amps are very sensitive to everything (especially guitar pickups) being very transparent sounding amps. I can clearly hear the difference between three different guitars for instance. I find my PRS with 245 pickups to sound rather obnoxious (bridge pickup is running around 9k). My basswood bodied 7-strings with Dimarzio PAF7s in both neck and bridge positions sound absolutely sublime.

[jjman]

The 3rd stage (V2a) doesn't reach saturation in my preamp. My voltages are lower throughout but I suspect this is also the behavior for a proper Express. The biasing and lack of a bypass cap on that stage cause it to clip on the “cold” (cutoff) end but I don’t see it reach clipping on the top where grid current and/or blocking distortion might be triggered.

I played with one on the PI’s input since I do see clipping on it’s top (and bottom) ends of the wave. No surprise on that. Only difference was a little loss in highs if it was over ~400k or so.

No harm in using them and earlier stages probably need more protection from radio frequencies and ultrasonic oscillation. 3rd stage appears to be usually safe w/o one.

[Colossal]

The 3rd stage (V2a) doesn't reach saturation in my preamp. My voltages are lower throughout but I suspect this is also the behavior for a proper Express. The biasing and lack of a bypass cap on that stage cause it to clip on the “cold” (cutoff) end but I don’t see it reach clipping on the top where grid current and/or blocking distortion might be triggered.

I played with one on the PI’s input since I do see clipping on it’s top (and bottom) ends of the wave. No surprise on that. Only difference was a little loss in highs if it was over ~400k or so.

No harm in using them and earlier stages probably need more protection from radio frequencies and ultrasonic oscillation. 3rd stage appears to be usually safe w/o one.

jjman,

My mistake, I went back and looked at the schematic. I meant what is marked V1a, not V2a. I entrance to the second stage, not the third is what I was referring to.

[jjman]

My 2nd stage doesn't clip at all so no blocking risk. Probably since the tone stack is snagging so much. Using a boost after the guitar could maybe get the 2nd stage to clip.

[cbass]

Didn't use any on mine .Didn't need em