Dwarf Tube Rocket Amp

[Dano]

I am playing it through 2x12" English greenbacks that are in a Marshall Bluesbreaker cabinet. It sounds fantastic with these speakers. I also tried it with an old Celestion Lead 80 that's in a Demeter TGA3 combo. It sounds good but not nearly as sweet as the greenbacks.

This is a gem of an amp. I'll post some pics one of these days. Rj is an absolute pleasure to deal with.

[RJ Guitars]

Dano,

Welcome to the AmpGarage and thanks for sharing some info on your build. I really wanted this amp to be a project where everybody involved helped develop this into a great little amp so I love getting the reports back on it. I plan to keep it available for the future and add our improvements and tweaks to the build kits.

It's great to know that this amp went together well for you. I have not had a chance to gig with this amp yet but I am pretty excited about seeing how well it does in the mix. It just doesn't seem like a lightweight amp as I listen to what it brings out from my guitar.

thanks again,

rj

[Dano]

Thanks for the welcome rj. I must admit to being a bit intimidated by the expertise on this site. I'll chime in if it might contribute to the discussion but will probably just observe for the most part.

I'm mostly just a guitar player and wood guy with quite a bit of guitar repair and a couple guitar builds under my belt. Tube amp building is new but so damn intriguing that I'm finally taking the plunge after lurking on this site and a couple others and reading a couple books on the subject. The V2 project was my 2nd build with a 1/2 watt Gilmore Junior being the first. Before that I put together several effect pedals. My next build will be a Rocket.

I really enjoyed building this. I did a lot of head scratching and checking and double checking my work with the schematic and actually feel like I learned quite a bit with this build as a result. The Little Rascal is my favorite amp right now. The sub-minis are too cool...it's hard to believe this little thing has such a huge presence. It's very responsive to the players touch and guitars volume and tone knobs. I've had success with all the pedals I've tried. It's taken them all very well. These include an old Boss CE-2 chorus, my favorite through this amp, phase 90, EH Frequency Analyzer, tube screamer, byoc vibrato. Chime, swirl and depth.

The only issue I had on the maiden flight was the volume not working if the bass was on 0. Rj suggested checking the trimmer and just like he thought it was on 0 so now all is well. Rj did a great job organizing the pc board and internal layout. I couldn't be happier with it and look forward to recording with it someday when time permits.

[kec]

Welcome aboard Dano! Glad to see yours is working. I'm slowly working on mine - as time permits. Waiting for a few parts from the Mouser.

As for speakers, I've got a WGS Veteran 12", WGS british 12" and some of those Celestion G8's.

[Zippy]

The only issue I had on the maiden flight was the volume not working if the bass was on 0.

Need to hang a 10K resister off the bottom of the trimmer to prevent that "opportunity"?

[stompjunkie]

First, a big thanks to RJ for putting together such a great project!

I finally finished my mini rocket a couple of days ago. There is a bit of background noise around 5kHz that I have to work out though. Instead of removing that little ammount of noise, I've impatiently moved on to tweaking. I tried the extra gain mod (I'm always a sucker for extra gain) and it was very cool. I decided to put it back to schematic values after that becuase I really only intend to use this for sparkly cleans and a bit of breakup.

FWIW I've been running this amp through a open back 2x10 with an Eminence Lil Buddy and a Legend. It's a very cool combination in that the Legend has all the sparkle I want and the lil buddy fills out some girth underneath.

I guess it's time to finally work out that but of noise (wich doesn't change with any settings or volume levels etc...) and then I can see about maybie getting a little bit more top end chime out of it.

All in all it's a very cool amp. Plenty of volume, really nice breakup, just the right ammount of compression, and a really nice non-harsh top end.

[RJ Guitars]

Stomp Junkie,

Congrats on joing the ranks of the V-2 community. Great sounding little amps and they like pedals too.

Do you think the hum could be a preamp tube? The one thing I've found with my three iterations of these amps is that they are all pretty quiet, even the one with the extra gain stage.

The grounding scheme is pretty important, mainly keep the preamp grounds away from the phase inverter and power amp grounds - that is don't share a ground lug between them.

I am currently on my way to the other side of the world but if you let me know I could arrrange for a tube to be shipped out if you have convinced yourself that the wiring is all good

... it just occurred to me. Do you have the heaters grounded? I had some bad hum until I tagged one of the heater leads to ground with a 1K resistor. If it is done correctly then you run a 100 ohm resistor from each heater lead to ground. I did the 1K resistor because it was in arms distance as I sorted out the problem. To test it ground one lead (or both using the 100 ohm resistors) and you'll know in an instant if that is it. This transformer doesn't have a center tap on the heater windings, you have to make your own so to speak. Ultimately use a 100 ohm resistor to ground on both leads.

I am in a hotel on a mini notebook but if I get settled into someplace I can look throughmy drawings I'll try to give you a drawig of that if you need it.

thanks,

rj

[M Fowler]

rj,

I sure hope these tubes make it through my assembly process, my hands are too big to be working with this small stuff and I'm not being very gentle I'm afraid.

But my wife came into the Man Cave and said oh that's cute She was refering to the tiny tubes mounted on the board.

Mark

[RJ Guitars]

Yes I understand... I have not grown fond of those little tubes although I have learned to work with them a little better. I almost quite on that first protoype more than once because they are such a pain. After you get done then they will be worth it... big sound for such small beasts.

rj

[kec]

Finally got around to stuffing the board. I'm using the machined sockets (just like the 'Lil Devil) mounted on the board using some epoxy (JB Weld).

Here's some pics...

[stompjunkie]

Hey RJ, thanks for the offer to send out another tube. No need though, it was a simple problem. The hum was just from a bad solder joint on one side of the filament grounding. She's perfectly quiet now! This is a really great amp. I find myself using this more and more! Thanks to everyone for the troubleshooting ideas on the problem I had.

[Zippy]

Finally got around to stuffing the board. I'm using the machined sockets (just like the 'Lil Devil) mounted on the board using some epoxy (JB Weld).

Is JB Weld conductive? Or are you keeping it well away from the pins?

[kec]

Is JB Weld conductive? Or are you keeping it well away from the pins?

I only put it on the plastic part of the socket.

[mclmk8d]

Here is the Pocket Rocket that rj built for my son Michael, who won't see it until he comes down from college. I played this for a while and it screams for a little mother! Nice distortion, excellent cleans and I can carry it with 2 fingers (though I won't!). I asked rj for something different, so I decided on a purple elephant tolex, which came out REALLY nice.
[img:720:554]http://img822.imageshack.us/img822/8286/img2030g.jpg[/img]
[img:720:540]http://img829.imageshack.us/img829/4053/img2033.jpg[/img]
To get an idea of size for those who don't have one (and you should!), here it is on top of the Carol-Ann
[img:540:720]http://img507.imageshack.us/img507/755/img2032x.jpg[/img]
rj, Mike is going to love this.

BTW, I was playing through a Bogner 412 Uberkab without any problem; seems to have enough power. Tomorrow, I'm going to try it through its eventual partner, Michael's Avatar 212 with a Weber Silver Bell and Weber Blue Dog, both alnico.

[RJ Guitars]

...BTW, I was playing through a Bogner 412 Uberkab without any problem; seems to have enough power. Tomorrow, I'm going to try it through its eventual partner, Michael's Avatar 212 with a Weber Silver Bell and Weber Blue Dog, both alnico.

mcl... keep in mind that the output transformer is rated at 8 ohms. I don't know what your cabinets are but the output tranny I use is a Fender Pro Junior tranny rated for an 8 ohm speaker.

That is a good looking little unit and allowed me to look into the various cabinet colors. The only down side is that custom cabinet work makes the delivery pretty slow.

rj