High Gain Rocket

[RJ Guitars]

Hello AmpGarage Forum,

Today I used that extra half triode in a Rocket amp as an extra gain stage on one of my little "V-2 Dwarf Tube Rocket" amps. For about $3 in parts you can do this mod to basically any Rocket amp.

The A/V quality is severely limited by both the guitar player and my digital camera. However, the raw video captures the changes in the gain very well through each phase of the demo and is probably worth the personal embarrassment to show you how it sounds.

http://www.rjguitars.net/V-2_HG.MOV

This idea has been bounced around but I haven't seen anybody Else's implementation before... could be out there. It is basic Rocket science but definitely not brain surgery.

It's kinda cool although not entirely clear to me that it is a winner. I'm not really a super high gain sorta guy so we'll need someone from shredderville to give us some perspective. I would need to gig with it to really see if I like it or not.

The mod is cheap and simple and if you followed my recent thread on adding reverb to a Rocket, that provided the technology and inspiration for this idea... which is somewhat of a backhanded thank you to Normster. I'm sure he would find his signature all over this design.

Thanks,

rj

[rooster]

Can't play it on my PC, RJ.

[RJ Guitars]

Can't play it on my PC, RJ.

I think it requires Quicktime... I have the 88MB Windows version... why can't they make it easy for us?

rj

[Colossal]

Sounds great RJ (!) and nice to meet you

[tubedogsmith]

On the rocket you can also change the mid cap to a .002 and the treble cap to a 500pf. This gives you a perceived earlier breakup and a thicker, gainier type tone. Not radical but some folks like it.

[passfan]

Pretty cool RJ. I could see that being on a footswitch, which would make it a tad bit more expensive. By the way, nice bench.

[rawnster]

hey RJ, I can't get it to play either. QT file never actually loads. Tried different browsers and such.

[Structo]

You have to right click and "save as target".
Then play the file.

Sounds great RJ.

I added the cathode bypass cap and put it on a footswitch for a gain boost.

But I haven't utilized the half unused tube.
Hmmmm, may have to give that a go.

So you wired a volume pot on the extra stage for a variable gain?

Sounds quite loud for the mini tubes.

How many watts do you figure on the output?

[Zippy]

It loaded for me - Quicktime plug-in running in Mozilla Firefox.

Did you dress up for that video?

Is that the dwarf tube Rocket?

What speakers are you running?

Coffee is on.

[Structo]

Can you tell us how you implemented the new gain stage?
Did you use a grid leak between the two plate loaded stages?
Did you simply wire the other half of the tube as a plate loaded stage then use the cathode follower and tone stack as normal?

[RJ Guitars]

The video requires a "Quicktime" application or plugin

Did you dress up for that video?

I wanted to wear something special

Is that the dwarf tube Rocket?

Yes - Protoype #2 with the Edcor power transformer. http://ampgarage.com/forum/viewtopic.php?t=9816

What speakers are you running?

Do they sound familiar? They are yours. A pair of Vintage 30-12's in an open back cabinet.

Sounds quite loud for the mini tubes... How many watts do you figure on the output?

Now you are asking me to do the math - which I never seem to get around to. The Lil' Devil is claiming 2 watts from a similar output section. Rob Breyerton built one of my V-2 Roc-Kit amps and he did some measurements that I think verified something in the neighborhood of 3 watts.

Can you tell us how you implemented the new gain stage?

Yes

Did you use a grid leak between the two plate loaded stages?

Nope

Did you simply wire the other half of the tube as a plate loaded stage then use the cathode follower and tone stack as normal?

I used the half triode as an independent gain stage. It looks a lot like the 2nd gain stage in the original schematic. Then I inserted it between the tone stack and the phase inverter. Everything else is still the same as the original Rocket. I actually used the cut control pot as a voltage divider to control how much gain to add. It really doesn't add a ton like I thought it would.

thanks,

rj

[UR12]

Sounds quite loud for the mini tubes... How many watts do you figure on the output?

Now you are asking me to do the math - which I never seem to get around to. The Lil' Devil is claiming 2 watts from a similar output section. Rob Breyerton built one of my V-2 Roc-Kit amps and he did some measurements that I think verified something in the neighborhood of 3 watts.
rj

The Lil Devil puts out 2 watts of "CLEAN power" (as measured on a scope with a 8 ohm dummy load) and about 3-4w when pushed to the limit.

[rawnster]

Got the file to play.

Nice, RJ. Sounds very cool. I don't know about the Twins t-shirt though.

It's interesting and funny how we keep wanting to dirty up the Rocket. Nice work though! for sure. I'd be tempted to put that extra gainstage on a footswitch or something. I'm always in "gig" mode; and have a propensity to step on something.

[rooster]

OK, I did save it and then play it. Pretty cool indeed, RJ!

[passfan]

The video requires a "Quicktime" application or plugin

Did you dress up for that video?

I wanted to wear something special

Is that the dwarf tube Rocket?

Yes - Protoype #2 with the Edcor power transformer. http://ampgarage.com/forum/viewtopic.php?t=9816

What speakers are you running?

Do they sound familiar? They are yours. A pair of Vintage 30-12's in an open back cabinet.

Sounds quite loud for the mini tubes... How many watts do you figure on the output?

Now you are asking me to do the math - which I never seem to get around to. The Lil' Devil is claiming 2 watts from a similar output section. Rob Breyerton built one of my V-2 Roc-Kit amps and he did some measurements that I think verified something in the neighborhood of 3 watts.

Can you tell us how you implemented the new gain stage?

Yes

Did you use a grid leak between the two plate loaded stages?

Nope

Did you simply wire the other half of the tube as a plate loaded stage then use the cathode follower and tone stack as normal?

I used the half triode as an independent gain stage. It looks a lot like the 2nd gain stage in the original schematic. Then I inserted it between the tone stack and the phase inverter. Everything else is still the same as the original Rocket. I actually used the cut control pot as a voltage divider to control how much gain to add. It really doesn't add a ton like I thought it would.

thanks,

rj

I think my hairs grayer than yours. I'm going to try that with my 6SL7 version of the rocket and see how it sounds.