music, guitars & other obsessions

All Aboard The Trainwreck Express

Why not?! After watching Glen Kuykendall’s YouTube videos, one can’t help but notice just how great his Trainwrecks’ sound, of course, his playing only adds to the experience, such great control!

After looking online, many have done the conversion, so I figure why not give it a shot, if I don’t like it, I can always restore it back to an 18Watt. The conversion seems pretty straight forward – change the cathode bias resistors, bypass caps and move the tonestack to just after the first gain stage. Also, I need to figure out a way to provide fixed bias for the output tubes – probably just go with a voltage multiplier off the filament supply, since the PT does not have a separate winding for the bias supply.

Addendum (7/9/2012):

After looking over the circuit and the construction, I have decided to re-do the turret board, as mentioned in my earlier post, I was never that happy with how the kit from Ampmart turned out. So now is a perfect opportunity to get it right!

Instead of re-using the original turret board, I will make a new one with the proper spacing for the parts, and move a few components around to optimize the layout. I will also change out all of the wires- instead of the thick multi-strand wires used in the original build, I will switch them to thinner solid-core wires, this should improve both the look and the sound of the amp (well it is worth a try).

Addendum 2 (7/12/2012)
When I fired up the amp, it was very noisy, so I spent a few hours trying to find out the cause… It turned out the noise was nothing more than some mis-wiring, doh! Should have checked more carefully before trying various “fixes” – luckily I did not make things worse, as it can easily happened. I will get back to tweaking the amp after my vacation… But it is good to know that the amp is fully functional and sounds pretty damn already, this one is a keeper! This is the noisiest amp I have build so far, need to figure out how to quiet it down – tried a few things so far but nothing helped that much – kind of a bummer because behind all that noise, there is a good sounding amp…

Here are the before and after pictures of the build, I stripped out a lot “junk” from the previous build – got rid of the VVR, the crappy fat stranded wires, and of course the whole turret board itself. I think the result is definitely an improvement. Working with solid-core wire was a breeze, but I had to really paid attention to the solder joints, hopefully no cold solder joint will show up later…

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2 responses

  1. So any updates on the 18 watt Exp amp?

    How does it sound as I’ve been contemplating doing a 2 x EL84 wreck-like amp,?

    I have built a ~10 watt express-like amp I have some info here: http://thriftywrecktour.wordpress.com/about/

    August 22, 2012 at 10:45 am

    • jazzbo8

      It is working just fine, I guess it does have the “wreck-like” characteristics – especially the C2M bit, really like the note blooming aspect as well. It is the only amp that I have that can even do that… I am currently running it with the Chinese 6P14s, they don’t sound half bad at all, I see you built the Thrifty Wreck, that seems like a real cool project as well. Will try and build one someday…

      Jaz

      August 24, 2012 at 5:28 pm

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