Paging Doug Hammond: Re - Meteor

[Mark Hammer]

Slowly working my way through the various etched-and-stuffed boards I have that need to be checked and wired up.  I rediscovered Doug Hammond's "Meteor" circuit today - a tube-to-FET adaptation of the Trainwreck Express amp.  Former forum member "Hairy Andy" Harrison once told me that he had tried one of these amps in his capacity as guitar tech for a number of major touring bands, and it was his holy grail of amps to save up for.  So I take that as a strong recommendation to come as close to it as I can, which led me to Doug's circuit.  It took me darn near 20 years, but I did get to it, and it fired up right away today, which made me very happy.  I adjusted the 5 trimmers on the board to get the drain voltages to around 4.5V for each of the J201s.  While all the controls do what they are supposed to do, it doesn't sound "right".  It distorts, yes, and can be clean when Gain is dialed back, but it farts out too easily, and isn't especially smooth.

Two mods were posted (that I know of) in 2004.  They are both shown in the attached schematic.  I did them, but something is missing in the sound, and I don't know what it is.  The expected "glassiness" is not there, and neither is the high gain.  Since it has been 20 years, perhaps there is some new knowledge, or changes, to help make the circuit live up to its goals.

Anybody know?

[zambo]

I'm not familiar with the schematic, but did you use a bright switch? They never sound right without that. I use the 500pf one. Just getting back into building things. Have been down the trainwreck rabbit hole for years.

[Mark Hammer]

I did get it working.  The problem seemed to be some solder lugs on one or two pots that were loose.  Just need to nail down bias voltages that allow me to obtain clean sounds as well as dirt.

I thought the "bright" cap (I use 51pf mica) could be implemented with a toggle, but lifting that cap results in a big drop in level, which I don't understand.  But it's a nice circuit.  Trying to decide whether to put it into a pedal or install it in my modular system.

[Kleber AG]

I can't open the schematic you posted Mark, it stays loading forever actualy never openning the image

Slowly working my way through the various etched-and-stuffed boards I have that need to be checked and wired up.  I rediscovered Doug Hammond's "Meteor" circuit today - a tube-to-FET adaptation of the Trainwreck Express amp.  Former forum member "Hairy Andy" Harrison once told me that he had tried one of these amps in his capacity as guitar tech for a number of major touring bands, and it was his holy grail of amps to save up for.  So I take that as a strong recommendation to come as close to it as I can, which led me to Doug's circuit.  It took me darn near 20 years, but I did get to it, and it fired up right away today, which made me very happy.  I adjusted the 5 trimmers on the board to get the drain voltages to around 4.5V for each of the J201s.  While all the controls do what they are supposed to do, it doesn't sound "right".  It distorts, yes, and can be clean when Gain is dialed back, but it farts out too easily, and isn't especially smooth.

Two mods were posted (that I know of) in 2004.  They are both shown in the attached schematic.  I did them, but something is missing in the sound, and I don't know what it is.  The expected "glassiness" is not there, and neither is the high gain.  Since it has been 20 years, perhaps there is some new knowledge, or changes, to help make the circuit live up to its goals.

Anybody know?

[Mark Hammer]

Hmmm, it does that for me too.  This one should work better.

[Andon]

[PRR]

Yes, the image hosting site has been wonky for days.

Try https://imgbb.com/upload