).
I’ll draw up a full schematic. The lazy loops are a signature piece of authenticity. There’s way too much chassis space left bare without them.Would still love to see a schematic of the preamp, there seem to be a lot of different versions of the Trainwreck Express, and it might be something I consider to build myself in the near future (without the lazy loops though
Jim, it’s really a 6v6 or 6k6gt setup. It’s got 337 volts on the plates and runs an 8k output transformer so it’s not running typical Express voltage (402) or 6.6k impedance.
I can only take credit for the chassis, faceplate and the finish on the cabinet. I called Mike Cauley from Faith Amps to see if he had anything. I’ve built 4 of these cabinets myself and they are difficult because the exposed joint work. I can do it but it’s stressful. I almost built a tolex cabinet with a maple or cherry face panel. Anyway, Mike had this cabinet, it’s got a small gap in the face panel and he was going to trash it. Oh no, well he offered to sell it to me and I couldn’t resist. He had finished it in Tru-Oil and it looked good but it wasn’t slick. I leveled it and shot it with lacquer. I lost count of how many coats but it’s over a quart. I shoot a few coats and sand. Finally got leveled out and was able to finish sand and buff.
It’s pretty close to the sound of a full wattage Express. The 6k6gt and 6v6gt really didn’t have the oomph. I’m still looking for a true pentode (not EL84) octal that’s got lower heater current than an EL34 (>1amp) but the 6P3S are working for now. The true pentodes have a softer clipping edge on the waveform, they compress as they reach their limits and the beam tetrode hard clips no matter what I try.
I’ve got all the notes in my book. I used the 150k because this amp can run 6k6gt, 6v6gt and 6l6gc. It gives it enough sweep to bias them all. Since I got a Power Station 100 I’ve just left the 6k6 in because they have more of the EL34’s feel and midrange I like. It only makes 11 watts with those tubes but the PS-100 let’s me do so much more with the amp, I’m satisfied with low power. I can make it really loud or just double it with a dry Trainwreck/wet PS-100 thing that’s unbelievable.
If you have a chance at some point to reference your notes I would really like to know what the voltages that you noted were. I'm going to build a lower wattage version as well.
I’ve got two clips earlier in the post. They aren’t good but they’ll give you an idea.
I can tell you that the important thing about the voltages is that they drop consistent with the original design through the power supply. My voltages are very consistent with the Liverpool model because I used nearly the same HT voltage and AC secondary before rectified. My power transformer is although much smaller than an Liverpool is capable of maintaining a strong HT voltage like the original. My transformer doesn’t have the current available to support the demand of 4 EL84 or 2 EL34’s but I didn’t want that capability. I’ll post my voltages, I just have to get around to it.
Thanks, I'm looking forward to seeing what you came up with.
