Originally posted by: Platypus
Snatchface, you'll probably want to go with an amp with a 6L6 power tube section. This gives you the subsonic lows and crystaline high end tone most prominent in 'American' tones.
A brief history lesson.. a ridiculous amount of amplifiers out there in production all trace their roots to Leo Fender's designs. Leo's designs in turn were robbed from old RCA vacuum tube manuals. Marshall for example started their empire by modifying the Fender Bassman circuit.. Mesa Boogie got their start modifying Fender Princeton amps and in turn M/B invented cascading gain by making old Fender amps 'high gain.' Almost all the famous amplifiers out there trace their roots by copying or modifying a different amplifier.
Marshall use EL34 power tubes, which along with EL84 tubes encompass the 'British' catalog of tones. EL34's are known for their focused midrange attack and harmonically rich upper midrange section. The classic British crunch you hear from AC/DC, Hendrix, old Clapton, Zeppelin, Sabbath, etc is an amplifier with that kind of power section.
So it depends on your ears.. I personally prefer 6L6's because they have a much better clean tone and can reach down into the subsonic bass territory far better than EL34's or 84's can. There are a ton more tube types out there but those 3 are the most prominent in current production amplifiers today.
6L6 will give you the best cleans and blues tones in my opinion. Metal is subject to taste... a shit load of 80s metal was created on Marshalls... but Marshall quality is absolute dick these days, I wouldn't purchase anything they've made in the last few years personally. There are lots of copies out there which out-Marshall any Marshall on the market right now.
I would honestly avoid a combo with built in effects, if you want the best tones I would go pure tube and not look back.. there's just nothing close out there honestly.
Your best bet is to find an amp with 6L6's with a master volume control so you don't have to turn your amp to 11 to get cranked tones and then pick up a nice overdrive for your metal kick. There is nothing in the 800 dollar price range that will 'do it all' without assistance of a pedal in my opinion. You are better off getting a great clean/blues/pushed tone and then using a pedal to push the preamp into a more compressed/saturated area for metal tones.
http://www.mesaboogie.com/Prod...fo/Express/Express.htm
The 5:50 is a kickass little amplifier.. it goes for 1200 bucks so it's a bit more than your estimate but you might have some luck finding a used one. They are brand new so it might be a bit harder but this would probably be your best bet for all the tones you're after in a small package. It also can scale down to Class( single ended power section) A mode as well as Class A/B (push/pull power configuration) and can get down to a much lower wattage than 50 (which is overkill for home playing) so you can get better power tube saturation at lower volumes.
Petrucci has used Mesa's exclusively for years. His famous lead tone comes from a Boogie Mark IIC+ and his rhythm is a Boogie Mark IV which he used exclusively up until the Six Degrees era where he had a brief stint with the Boogie Dual Rectifier.. he has since gone back to the Mark IV and C+ for the newer stuff. The Express won't give you access to his tones exactly but they're close enough and the closest you'll get in that price range.
I would recommend a Mark IV for you normally but they're pricey, even used, they go for around 1K and they're extremely complicated, especially if you've never used a tube amplifier before. They have tons of bells and whistles and are honestly probably more complex than you need for a basic kickaround combo amp.
If you're looking into a British tone as discussed above, the Orange Rocker 30 can be had for around 800 used and is a kickass little amplifier. Pair it with a nice OD on the dirty channel and you'll be coping Sabbath for days, the cleans are surprisingly good for an EL34 tube amp.