2xel84 rocket

[Zippy]

Thanks, Mark.

Looks like I need to get with RJ to do the definitive comparo.

Cheers!

[BarryW]

Mark, thanks so much for posting your build and your expierience. I continue to just be thankful for the great info in this community, I have learned a great deal and hope to learn more. My skull is thick, so it takes a while!

[RJ Guitars]

... The quad EL34 is definately the tone pleaser that covers everything I need in an amp highs, mids and lows with nice blend of short decay reverb. It gets dirty about noon and if I switch in my boost option it gets the harmonic thing (ZZ-top) even sooner. Running Edcor 100w iron.

Mark

Quad El34 - is that loud enough?

rj

[Zippy]

RJ - Care to comment on the "complexity" issue of 2- vs 4- holer Rockets?

Can you hear a difference if you just switch to half power by neutering a pair of EL-84s in the standard Rocket?

[M Fowler]

Thanks guys I learned about the TW amps from this place with all the great data others have compiled and Ron Worley's layouts/build section.

I try to give back as much as I receive but terrible making schematics or layouts for people to follow along on the adventure.

Mark

[RJ Guitars]

Yeah.... I think I just posted something about this on the post by Angelo over in the technical discussion page so it's fresh on my mind.

I think the sound is a little more complex with all four tubes working together and a bit more edgey in the half power setting.

If I can make a simple story not... I hear more harmonics and smoothness that kinda feels like all the tone gaps are filled in with the 4 tube output. The two tube output has a more in your face sorta bite. If that makes sense?

I also believe in the notion that a mismatch in the output tubes can tend to sound more complex than the perfectly matched sets. I haven't been especially scientific about this but have noticed the phenomenon on a few occasions. Now I don't tend to intentionally mismatch tubes as much as I just don't worry about matching them and use my ears as the tube tester.

rj

[M Fowler]

Hello rj and all,

I find that my new two EL84 amp no switching doesn't have that Vox chime and sounds more like a Marshall IIB. No choke

The four EL84 switched Rocket still seems to have the chime in 36w position and a lot less in 18w position but not as Marshally as the above amp I described. They of course were built completely different from each other in the power supply and this one has a choke with typical cap values found in a Rocket.

Mark

[RJ Guitars]

Hello rj and all,

I find that my new two EL84 amp no switching doesn't have that Vox chime and sounds more like a Marshall IIB. No choke

The four EL84 switched Rocket still seems to have the chime in 36w position and a lot less in 18w position but not as Marshally as the above amp I described. They of course were built completely different from each other in the power supply and this one has a choke with typical cap values found in a Rocket.

Mark

So can we say the choke is responsible for the chime or maybe adds to the chime or is it the power supply caps or ???

Just wondering of anyone has built a Rocket without the choke and maintained the chime.

rj

[M Fowler]

rj,

This is the only 18w Rocket I have build and the only Rocket amp without a choke.

Mark

[Zippy]

So can we say the choke is responsible for the chime or maybe adds to the chime or is it the power supply caps or ???

Sounds like one of your amps needs another switch!

[telentubes]

I just finished a Watts style Spitfire (like the one Mark built) without a choke.

Are you guys thinking that replacing the resistor with a choke might give the amp more chime?... or that 4 tubes may chime more than 2? I love the amp as is (more Marshall than Vox), but who would say "no" to chime on a 15 watter. Perhaps, non of the above is directly responsible. Just curious. I guess I should put in a switch, do the legwork myself, and report back.

[Zippy]

Are you guys thinking that replacing the resistor with a choke might give the amp more chime?... or that 4 tubes may chime more than 2?

Yes, those are the questions.

Just curious. I guess I should put in a switch, do the legwork myself, and report back.

More data is mo' better - even if somewhat subjective. I'd love to hear back from you.

[M Fowler]

I would think that the four EL84's are responsible for the chime.

I suspect that the DC resistance of the choke plays a part as well.

When looking at the Hammond 158L choke for the Rocket it is 15 Henry 75mA and 411 ohms DC resistance. Not sure what the real choke for this amp was or should be.

[M Fowler]

MC finally has the standup (verticle mount) 18w PT 120mA available.

Mark

[argonaut]

I finally found my camera. I'm a poor photographer, but here's some pics as promised. Been tweaking a bit, and now have the input paralleled with 120k/750R/22uf. Sorry about the wrap on the components, not trying to hide anything, just get a bit artsy fartsy and weird on some builds. It's a rocket with a few exceptions.

Anyway, here's the poop:

PT-vintage Stancor 270-0-270
OT-vintage Hammond 1618
CDE 381LX 33uf reservoir cap
CE Manufacturing 20,10,10,10 multi cap
1K 10W resistor in lieu of choke
Holco H4P plate & grid R's
Sangamo dominoes
K-40Y-9 couplers
PVC tone caps
100R screen R's
100R/220uf cathode

Pull Bright= 120pf mica across the standard 100pf
Pull Attenuate= 220k to ground at PI entrance
Pull Mid-Cut= two 50k trim, one set for desired mid (in lieu of 10kR) the other to dial in the amount of cut when pulled...
Pull Shift= cut set at .0022uf, .0044uf when pulled

Baldwin label Sylvania in preamp and Russian 6n12n-k power, RCA 5y3

B+ 295V, 285v on the plates

I didn't plan this build, just unexpectedly got the chassis and it came together. I ordered the faceplates and multicap and pieced the rest together from what I had around. All the push/pull tweaks are very useful when playing with multiple guitars. I have to get busy making some head cabs now. I have too many naked chassis' piling up. Going to go picking through the wood pile tomorrow and make some dust!

Edit: Just remembered a few other details, although not crucial, thought I'd mention it. Couple other component details:

NOS CTS pots
NOS Cinch sockets (used the grounding lugs on the pre/PI section)
Chily 15A switch
...tied up with string, these are a few of my favorite things...