Firefly built

[Connoisseur of Distortion]

some of you will remember me asking about this awhile ago. well, i finally got myself working and the end result is an amplifier.

it has problems, but worked first try (  ). it doesn't have quite the grit of the soundclips, but i am just about certain that my issue is the boost switch, which i ended up wiring upside down. it also oscillates a little, but i have observed the messups of builders past and i have decided that i will try rearranging the switch, then try to isolate the power transformer and output transformer with metal plates, then go into the amp again and start messing with wires ( :x  :x  :x ).

this was my first ever project with plate voltages. i built the firefly into an amp about 6" X 8" x 2" without incident. all components were placed onto perfboard and wires run to them. i first tested the power supply and got reasonable voltages. after doing so i used a 10 watt 30k resistor to lower the capacitor voltages to not-killing-user levels. i think that the 10 watt is nice because it has rigid leads and is easy to grip without touching said leads. you could probably get by with a smaller one   .

people i want to thank? everyone who's built one for giving feedback, Paul Marossy for his VERY helpful layout, and Doug Hammond for his wonderfully simple (and great sounding) amp!

[lovekraft0]

6x8x2? Whew, that's tiny for a tube amp - I've never even attempted to put one in a chassis less than a foot long! Udaman! Are you having any hum problems with the OT that close to the PT?

[Connoisseur of Distortion]

please remember, this thing only has 3 nine-pin tubes, a 269ex, and a 125A to hold on it's top, so it's not exactly a crowded surface  

the OT and PT are on opposite ends of the chassis, and i have not yet heard any hum... but after about an hour of tweaking, i still get oscillations when i have the boost on or my volume at about 9-10. i am kind of regretting the small enclosure because of this, but it'll make a great little head to carry around   .

i actually just threw together a cab from a friend's old Stage 100 that crapped out and his celestion that was inside. i took the side of a RACO box and drilled holes for 2 jacks and 3 screw mounts, which has been firmly attached to the front under the velcro down grill-thing. i now have an open back 1x12 with 100 watts power handling!  :lol:


just sat down and played it some more, and i have to say that it has a very sweet tone to it. the harmonics are not painful, the bass is rich and full, the mids just fill up the room. great sounding little practice amp.

EDIT:

just thought i'd mention that i also subbed out the filter caps for 33 uF instead of 47 uF, and that i have no noticeable hum. in case you even cared...  

EDIT EDIT:

oops. placed my edit in the middle of my post  :?

[Connoisseur of Distortion]

holy crap!

i went back at it, and it is now good! this thing went from being a great little amp to being an amazing little amp!! one cold joint changed everything!

:shock:

it also now wakes up people in nearby rooms (it's 3 AM here) but i could not care less. i am completely preoccupied.

everyone should build one. it's silent (completely... no joke) when dampened, aggressive when cranked (sounds a bit higher gain than marshall, a bit lower than mesa), and probably all you'll ever need in volume for practicing (if you like feeling it in the floor).

[Doug_H]

Glad you are enjoying it.

Now try this:  

http://home.cfl.rr.com/dbhammond/Firezog.gif

(:lol:  :lol: )

BTW, for anyone who is interested, Chris Hurley (ax84 site admin) is now offering Firefly kits:

http://dobermanamps.com/shop/index.php?main_page=product_info&cPath=1&products_id=24

This will make it easier for people who don't want to source all the parts themselves.

Doug

[Connoisseur of Distortion]

Mr. Hammond, your design is fantastic. I absolutely love it.

people!! listen to what he says! a kit would be so much easier! i have been planning to build this for a few months, but i had to order parts from all over the place... and thus it took just about forever. it's only about 10-12 hours of work when you actually have everything there in front of you, but getting prepared can take ages!