TW Rocket Right For Me?

[mauiboy81]

Hi guys,

So here is the scenario.....

I have a friend who asked me to build an amp for him. He is in a pop rock type of band that blends a lot of electronic/synth type stuff with organic instruments. When he plays electric guitar he just plugs straight in to his amp clean with no effects (he has a lead player who does all the effects stuff). He wants a nice punchy chimey clean with an edge maybe a little grit when pushed.

I was looking at doing something like a stripped down AC30 with only the top boost channel into an octal power section. That's when I thought about looking back here and saw the Rocket and the Rockster variation. In the past I spent most of my time in the dmble forums and never really checked the Wreck. But man these look like sweet amplifiers!

So does this sound like the right amp for the job?

Thanks,

Nick

[geetarpicker]

Sounds like a very good choice actually!

[skeezbo]

Everybody seems to love the Rocket, but maybe you should also consider how loud he needs to play, and how clean? A Twin Reverb would have more clean headroom and fuller fidelity than any of the two octal Tweed/Marshall/Vox variants.
Skeez

[RJ Guitars]

Welcome Mauiboy to the world of the Wreck... great amps and great folks over here. Of the three primary Wrecks, the Rocket is the "utility amp" that allows you to use it straight or is very pedal friendly. If you want over the top Wreck performance then the Express is the big deal... clean to mean with the turn of the volume knob on your guitar, but no significant change of volume in the process. The Liverpool is very aggressive sounding as well but I don't think it has the same punch as the Express. Each of them serve a great purpose and do it very well.

For myself the Rockster can sound like a more powerful Rocket but has the ability to offer more tone variations depending on your choice of output tubes. Also component choice and B+ voltage can voice the amp in many different ways.

The Rocket and Rockster are very forgiving circuits that allow you some liberty in the build layout. The Express tends to sound best when you stick with the known formula but most determined folks can dial them in to be great sounding amps if they work at it. IMHO - The Liverpool is not as fussy as the Express but still requires adherence to the known layout to make success come easier.

In all cases there are many great Wreck gurus available if you want help dialing them in...

rj

[Zippy]

A Twin Reverb would have more clean headroom and fuller fidelity than any of the two octal Tweed/Marshall/Vox variants.

He wants a nice punchy chimey clean with an edge maybe a little grit when pushed.

By the time you get a lil' grit, a good Twin can be painfully loud.

+5 for the octal Rocket, aka Rockster 66 (w/ KT66).

[M Fowler]

I would have your friend go for the TW Rocket, nice and chimey, plenty of volume, and to get more headroom without low volume gain adjust the 220k V1a plate to 100k-150k range. I seem to settle on 120k mostly.

If he does want to have a boost function the foot switchable or mini toggle switch can be used to kick in a cathode bypass cap on V1b.

Also, take advantage of using a DPDT mini toggle bright switch with 100pf one way center off and up 250pf to 500pf range rather then the 100pf cap on the volume pot.

Mark

[dorrisant]

If you build a Rockster for someone, you will probably end up building one for yourself!

I love mine... everything else has been collecting dust since mine was ready...

Fun to build too... not very complicated.

Tony

[mauiboy81]

Thanks for your input guys.

The Rockster is pretty much exactly the amp I was building in my mind.
I love the simplicity of it.I haven't built him one yet and I already want one for myself! I may consider adding reverb but I'm not sure yet.

Although I love a fender Twin I don't think I want to go that route on this one. I do have a 69 Dual Showman Reverb I am probably gonna rebuild soon.

I am definitely considering a 3 way bright switch. The V1b Cathode bypass cap is interesting too. What value have you used 5uf, 10uf?

Is the 1.5k cathode resistor the right value with the 220k plate resistor? I have used 100k/1.5k but with the higher value plate resistor don't you want to use a higher cathode resistor to keep it biased correctly?

I have a Heyboer 4k:2,4,8 bassman OT..... will that work well for this?
What is the proper PT HT for the octal tubes? I like the idea of the dual HT for High and Low power.

Has anyone tried a 4 6v6 version?

Thanks again guys! You are great!

Nick

[dorrisant]

You may like the Rockster as is without a bright switch... I do.

As far so the ot... Most use 5.5k taps... Pretty sure you can use 6.6k. I don't know about 4k... Let's others chide in.

If you haven't already, you should read this for some tasty mods:

http://www.ampgarage.com/forum/viewtopi ... t=rockster

And

http://www.ampgarage.com/forum/viewtopi ... t=rockster

Tony

[dorrisant]

Also... rj's Road Rocker is a Rocket with 4 octal output section.... But I have to tell you two EL34s are plenty loud enough. You could always try different tubes, octals anyway. I would suggest some KT66s... thanks to rj...
Tony

[mauiboy81]

Hey Mark, when you say you like 120k on V1a plate what voltage do you get there?
Also, in another thread you said you liked to run your rocket on the higher voltage PT taps.... is that so you get higher voltage on the power tube plates and more clean headroom? Do you adjust the PS dropping string to keep the preamp tubes the same as with lower B+?

RJ, Thanks for the kind welcome to Planet Wreck. I feel at home here. Thanks for your effort to help others find their way with these circuits!

Tony, thanks for the links...... after I looked at them I wondered why they didn't come up first when I searched for those very topics and I realized after a bunch of searching with no luck that when I select the "search for all terms" I get way better/ more specific results and found those threads.

The 4k OT I have was made for 6l6gc's but is that more suited to amps that run with higher plate voltage?

Thanks you guys! It looks like you have had a lot of fun with these designs over the past few years! How are your ears?

Nick

[M Fowler]

Nick, I like the plate voltage to the power tubes higher yes. But after building some with 300-0-300 TW PT I have switched to 280-0-280 or 290-0-290 because of recommendation not to go so high on my plate voltage.

Today's tubes are not built as well as NOS tubes and based on what I have heard in my amps no difference as far as clean headroom or power by lowering the plate voltage. There is a big difference using 120k verses 220k on that Rocket V1a plate though. Cleaner/more headroom.

You have to adjust the dropping string resistors but that is something people should be looking out for anyway when they take voltage readings. You may have to replace dropping resistors to get the preamp tubes voltage inline.

Following a proven schematic or layout isn't a bad thing to do sometimes. I have a habit of always changing my amps from the norm