Rocket/Rockster mods

[analogjunkie]

i am looking for ways to expand my new build a bit. it is not nearly as loud as i thought it would be, and it gets dirty very fast. i would like to get more volume at least. every tw i have played is a good bit louder then my build.

after looking at the different tw schematics and layouts i notice the rocket has no cathode cap on V1 pin 3, or the anode snubber cap on V3 like the express and liverpool. i would really like to get some input before i go tweaking to nowhere. thanks in advance!

[Fischerman]

Are you sure it's working correctly and putting out full power? It might not scream like an Express but it should be loud and full. Adding a cathode bypass cap to V1-3 is definitely a viable mod, the Zwreck has it. A snubber cap is often more for stability (shunts uber high frequencies) and with the (relatively) lower amount of gain in the Rocket preamp, it isn't required.

[M Fowler]

You can add the bypass cap V1b as stated and change the 220k plate resistor to 120k-150k area of value V1a for less gain and more headroom.

The amp should be plenty loud stock but the lower plate resistor will improve less dirt until you turn the amp up.

May want to check the known voltage readings in the TW file section to compare your voltages with. May need to increase your preamp voltages some. Edit just noticed this was the Rockster never mind.

Also look for wiring errors.

Mark

[Zippy]

Edit just noticed this was the Rockster never mind.

Most everything north of the output section is the same - it's a good reference for voltages throughout.

OP: What trannie set did you use? Is it a Rocket or a Rockster? What tubes are you running?

[RJ Guitars]

You can make some measurements and figure out how much power you are making but it should be between 30 and 35 watts. Depending upon the situation that can be stupidly loud or not enough, but most folks end up using power brakes, variable voltage regulators, and/or master volume controls to bring the volume down on these amps.

To get more clean headroom I suggest the PIG (Phase Inverter Gain) control. This borrows a page out of Ken Fischer's "Trainwreck Pages" and is a simple mod that allows you to vary how much signal you put into the phase inverter section.

If it's really a matter of needing more power you might think about building something like my 80 Watt "Road Rocker" amp which is the same basic circuit as the Rockster but you can choose between a pair of KT-88's or a quad of EL-34s/KT-66's or what ever octal output tubes suit you. This will be louder but not 2x louder... more like it goes to 11 and is "one louder".

rj

[M Fowler]

Pop in a pair of 6550 tubes and use a SS rectifier plug instead of the GZ34/5AR4.

Mark