Dwarf Tube Rocket Amp

[RJ Guitars]

Hello AGF

After too many posts and not enough builds by myself, I finally finished something tonight. I've had this project on the back burner for a long time and finally got the time and inclination to finish it off.

I've built the "Dwarf Tube Rocket" using Sub-miniature military tubes. I used the Rocket schematic as my starting place but had to change values on several components to get the amp to clean up. It now sounds extremely good and has all the Rocket vibe in a small low wattage package...

I used what I had here in the shop to build it including a piece of vintage Vectorbord. The power transformer is a Stancor and the output tranny is from a Pro Junior. I have three single triode tubes into a dual triode phase inverter and finally into the 5902 output tubes. I used cathode biasing, a solid state rectifier, and a big resistor instead of a choke.

It sounds amazingly Rocket like and I'll try to get some clips so you can sample the sounds.

rj

Edit Sept. 1, 2011 - I am adding the latest version of the schematic and layout here and will update it on this page each time I make a change in the future. Please note that the layout & schematic will not match the photos on this same page because the amp has evolved from that initial effort.

[MCK]

Great idea and great execution by the looks of it. Can't wait to hear the clips.

[M Fowler]

rj,

Interesting build you have there and anxiously waiting for more info.

[UR12]

Looks Cool........>So how bout some gut shots?

[RJ Guitars]

Hey Guys,

The more I play this amp the more shocked I am at how good those little tubes sound. This amp is so small that you can hardly see it next to me in the video clips but it sounds really big and full. I think it might still be improving but it's among the very best that I've put together so far.

Here are some garage quality clips for you. As you might expect neither the playing or the recording is stellar but the character of the amp is apparent and I have my doubts that my playing or recording will be improving soon so I want to get the clips over with and get on with the next amp to be built. Thank you for your indulgence!

I went through a lot of pain this evening trying to edit out me walking back and forth from the camera and tuning the guitar, but the sound changed with three different A/V editors I tried so you get the whole ugly batch of it... You'll need QUICKTIME player to view the clips. It's a free player from APPLE. The videos take a good minute or so to load after you click on them.

The first clip you can hear the good clean sounds very well and each position on the Stratocaster really sounds unique and clear. The second clip the audio spectrum showed that the signal was over-driving the camera input so it's probably not quite as distorted as the video might lead you to believe. I think this would make an awesome amp to record or gig small venues with.

http://www.rjguitars.net//Dwarf_Rocket_1.MOV
http://www.rjguitars.net//Dwarf_Rocket_2.MOV

rj

[MCK]

Wow! Sounds great indeed! Thanks for taking the time to tape & post. I would love to build one to go along with the express inspired Lil Devil's I have. Would love to integrate Dana's VVR though to level the playing field.

Would you be kind enough to post more info on the build details?

[RJ Guitars]

Looks Cool........>So how bout some gut shots?

Dana,

The inside of this looks a little like a prototype amp... which is to say there are a few things I'd like to clean up before I document anything funky to try to explain later.... not that I'd ever do anything funky! I guess I was so surprised with how well it works that had I known I would have gone for the pristine build technique... nah!

Wow! Sounds great indeed! Thanks for taking the time to tape & post. I would love to build one to go along with the express inspired Lil Devil's I have. Would love to integrate Dana's VVR though to level the playing field.

Would you be kind enough to post more info on the build details?

Yes indeed I will share the details and if I am not getting them up here fast enough feel free to PM me for something specific. To me, amp secrets tend to keep you looking over your shoulder rather than where want to go next... I'll gladly help others with what I learned.

Now that I've built one I have some good ideas for the improved version and I'd enjoy company if anybody wants to build something similar. I've located everything including a good line on a dependable source for tubes.

thanks for the good words.

rj

[camden_guitarist]

AWESOME man!!! Nice playing and great sounds!!! You'll be putting a kit up soon on your site?

Cheers,

Paul.

[kec]

That sounds great RJ!

[Blind Lemon]

Sounds great RJ..........were'd you have the volume set for those vids?

BL

[sst4270]

Very nice RJ. And of course what were you playing the amp through?
sounded like maybe a single 12".

-Steve

[dimi3]

woow nice tone... I would be interested in details too..since I missed Dana's devil, i'm looking to build something low power for home use..

Keep up the good work..

[RJ Guitars]

... Would love to integrate Dana's VVR though to level the playing field.

Would you be kind enough to post more info on the build details?

Thanks MCK - These amps are louder than I expect although they are not anything you'll need earplugs for. If the drummer doesn't pound things it would work for the small venues on it's own. I don't know what would happen if you added the VVR because it is a really low voltage outfit to start with. Looking at the preamp tube specs and listening to it, I'm not sure if I'd like how the preamps tubes perform at lower voltages.

AWESOME man!!! Nice playing and great sounds!!! You'll be putting a kit up soon on your site?

Cheers,

Paul.

Thanks Paul - I was always one of those players that couldn't quit my day job, so your words are kind.

This amp was a pure raw prototype where I tried a few new ideas... they all seemed to work and each even better than I anticipated. I'll use all I learned to put together a kit. but I'll probably put together a dozen for the next iteration and test run them on the forums before I add them to my web site.

That sounds great RJ!

Again you are too kind. I have found that this amp really seems to sound best after I've played it for a while. I'm not sure if it's me or if that is a real thing.

Sounds great RJ..........were'd you have the volume set for those vids?

BL

Imagine that tone in the hands of a great player! The amp is between 7 & 8 (2 & 3 O'clock) and the guitar is set at 8 for ultra clean and then 10 when I push it to break up in the 2nd video. I also played my 339 through it and the results are similar although the sparkle doesn't come through so much with the humbuckers.

One cool thing it does is that the volume control is pretty linear and it really gets quite a bit louder between 8 and 10.

Very nice RJ. And of course what were you playing the amp through?
sounded like maybe a single 12".

-Steve

Good ears Steve. This is actually a pair of Vintage 30 12's in an open back cabinet. It's a very good sounding cabinet and is great for amp testing. I've also played it through a set of mixed 10's in an open back cabinet and I like those as well.

woow nice tone... I would be interested in details too..since I missed Dana's devil, i'm looking to build something low power for home use..

Keep up the good work..

These are definitely a good home amp, although last night my wife actually came back to tell me she couldn't hear the TV and I needed to turn it down... she just doesn't get it? I guess the house isn't all that big and she is just in the next room though.

I'll try pedals through it later and let you know how that goes but it sounds so Rocketish that I expect them to work nicely together.

Let me know if you want to help prototype the kits. They are pretty simple amps to build and the parts will not be bad at all. Protoype kits will be my typical no-profit lets have some fun protocol.

Thanks again for the kind words.

rj

[Zippy]

Are these tubes prone to the microphonics associated with other tubes of similar aspect (e.g. EL84)?

What is the life expectancy of these tubes given that they are soldered onto the board?

[Structo]

Sounds great RJ!

Nice full tone from those little tubes.