Rocket Group Build project

[UR12]

Myself and Pureoldsound are getting ready to start Rocket builds together. I thought I would start this thread to document our progress and share ideas. If anyone else is interested in joining in or just sharing ideas please jump right in. There isn't as much info on the Rocket as the Liverpool and Express. The schematic in the files section is actually documentd from a Two Rock clone. I haven't seen any pictures of a real Rocket but will be using Mark Abbot's schematic and layout along with a Liverpool power supply as the Liverpool and the Rocket shares similar power amp sections. If anyone has any info or has already built one, what did you use on your build as far as values and such.

The Two Rock clone info shows a 4.2K tranny. What did you guys who already built one use? I have a NOS Stancor A-3800 that is 5.2k that I am going to use as the Liverpool I built sounded great with the 5.2k primary. Any help or insights would be greatly appreciated.

[mhuss]

hi Dana,

Sign me up! I've been meaning to build one of these, and I have a JTM45-sized chassis and a few old Stancors and Triads laying about looking for a home.

--mark h

[UR12]

hi Dana,

Sign me up! I've been meaning to build one of these, and I have a JTM45-sized chassis and a few old Stancors and Triads laying about looking for a home.

--mark h

Sounds like fun Mark. It will be cool if we get a few of these built as a group and see how close they sound to each other. I am planning on getting the boards made up this week and hope to start mounting Trannys and tube sockets by next weekend. We can post some pics as we go and maybe come to some kind of consensus on what parts/values sound the best.

[philmanatee]

I used Moose's trannies with the 5.2k taps. Phil

[Allynmey]

I'm in!

[philmanatee]

If you guys come up with some more info than has been available I'd be into building another one that was more of an exact clone. Phil

[UR12]

If you guys come up with some more info than has been available I'd be into building another one that was more of an exact clone. Phil

Phil

What tranny impedance did you wind up using. 4.2k, 5k??

[philmanatee]

I used the 5.2k tap on the toneslut iron. I'd like to make as exact of a copy as I could just to compare my trem-rocket to. Phil

[pureoldsound]

Yup, can't wait to start on this amp...I have to hear why people claim that this one is the best Wreck of all...BTW I'll be using a 4.2K, it will be a great way to compare amps once finished with those using 5.2K...I'll be using a 15H 100ma choke as well...There are Vox replicas, but I think they run on 10H 100ma....Also there is the option of just using a 1k 25w resistor...Lots variations to compare....

[paulruby]

Here's the info about the versions I've made, which sound really great...

I used the standard wreck iron. 5k2 primary OT and 295VAC PT. 5AR4 recto delivers about 370V B+ to the EL84s. I like high B+ on EL84s.

I followed Mark Abbot's preamp schematic and used the same power section as the 36W over at 18W.com. I did NOT use a choke as I don't think it is needed.

Pics of one...

http://www.paulamps.com/DSCF0134.JPG
http://www.paulamps.com/DSCF0135.JPG
http://www.paulamps.com/DSCF0136.JPG
http://www.paulamps.com/DSCF0137.JPG
http://www.paulamps.com/DSCF0138.JPG
http://www.paulamps.com/DSCF0139.JPG
http://www.paulamps.com/DSCF0140.JPG

Wiring diagram:
http://www.paulamps.com/RocketWiring.gif

Note the bright switch drastically alters the treble cap in the tone stack and also modifies the first coupling cap to keep the bass properly inline with the mids and treble from the tone stack.

Power board wiring:
http://www.paulamps.com/RocketPSU.gif

Let me know if you want any help or what ever with your build. I'm happy to contribute.

[UR12]

Thanks Paul! Great info!! Please chime in anytime. So you used the bright switch on your Rocket builds? I was just taking note the other day that the Rockets I have pictures of didn't have the bright switch feature. I was just trading PMs with Rhinson regarding the use of a Dynaco a-270 tranny the Dave Funk had purported that he had used on some of Ken's builds. They were a 4.2k tranny if I remember corectly. I am also using a 5.2 on my build but some of the others out there might want to try the Dynaco iron. This is all interesting stuff.

[Custom 100]

Here is some Dyna transformer info/specs from the Triode Electronics site. I think they sell Dyna clone transformers as well. Might be a cool alternative to the "standard" TW iron.

http://www.triodeel.com/images/dynaxfmr.pdf

[paulruby]

Thanks Paul! Great info!! Please chime in anytime. So you used the bright switch on your Rocket builds? I was just taking note the other day that the Rockets I have pictures of didn't have the bright switch feature.

You're right that the originals didn't have a bright switch. But, in a discussion, I think on this board (I need to do a search) the topic of tone stack values came up. I built my first rocket with "normal" tone stack values, which means marshall tone stack. This gives the high-mid peak that we all know and sounds great with EL84s when palying hard. Great overdrive sound.

But someone, and I forget who now, suggested alternate values. In particular, the treble cap reduced from 470pf to 47pf, which gets rid of the mid peak. This also resulted in too much bass, so the first coupling cap was cut from 1nf to 500pf. This sounds really great for clean and mild over drive conditions. Crystal clear with excellent string separation and chimey in the top end.

So, the "bright" switch is really changing the treble cap and the first coupling cap to switch between the two above settings. It actually makes too big a change to the character of the amp to call it a bright switch.

Anyway, figuring out exactly what tone stack values to use to get the true sound desired seems to be the challenge. I'll try to find the original discussion and add a link...

[johnspeck]

http://ampgarage.com/forum/viewtopic.ph ... highlight=[/url]

[Curly]

great idea!!!

I fell in love with johnspeck's Rocket that Paul built, and he says that amp sounds great.

there does seem to be less info on the Rocket, so it will be interesting to see what brainstorms folks come up with.