Building a Rocket - Layout Check for group build

[RJ Guitars]

Hello Forum - As I prepare for this Rocket group build part of my intention is to gather and grow the collective knowledge on these amps... I recognize that we are in the dark a bit for documentation on the Rocket, but in the end I bet we will get some new info added to the knowledge bank...

Perf Board:

Aside from the question about the layout for the Rocket PS board, there are a couple reasonable safe assumptions I've made. One of those is that KF probably made his boards out of the same perf board he used in his other amps. Thus, the following questions:

1) What did KF use?
2) Where did he get it?
3) Is it still available?

I'll answer my own questions then let everybody else chime in and see what we get out.

I believe the original Perf Board was something called Vector Bord made by Vector Electronics in Glendale California. The samples seen in the picture below were picked up along with a bag full of the matching flea clips from a government surplus salvage vendor.

As it turns out you can make exactly two sets of Express or Liverpool circuit boards from one full sized piece of Vector Bord, there is no left over material. The holes are .100 inches in diameter and .265 inches between centers and it is .95 inches thick. It is 17 inches long and 4.75 inches wide.

Vector Bord is no longer in production, but several guys here on the forum have created their own product that is the same specs. I don't know if anyone makes a flea clip or not... but there are lots of good turrets available from various sources.

Maybe Omar will archive these images...

rj

[UR12]

Your build looks great... how does she sound?

It sounds very different from the Express or the Liverpool. Its more of a cleaner sounding amp of the three.

As to the authenticity of the Rocket PS board layout, I can only let Tubedog answer for himself... I don't know if he meant that to be gospel or a personal inclination. I have scrubbed the archives pretty hard here and elsewhere and I will admit that I didn't find a Rocket Power supply board anywhere documented as the real deal.

Pure speculation on my part, but with all due respect the board layout that you have drawn and verified by Tubedog looks more like the Two Rock clone. I don't think that anyone has posted any pics of any real Rocket power supply boards and that's why they aren't documented here.

I'd be inclined to feel that the standard layout of the Liverpool PS would work make sense and serve for the Rocket. I'm a little concerned about that 80uf cap against the GZ34 rectifier tube... if that could be softened up I'd be all for that. On that PS board the little notched cutout makes it kinda look retro cool... I'm not qualified to answer as to the authenticity though.

I've never seen any pics of any of Kens amps sporting the Trainwreck name that had a single 80uf cap. He always used 2 40uf caps in parallel. The data sheet for the GZ34 specifies 60uf max cap. One thing to note on Kens amp is that the first filter stage was always before the standby switch and this means that the first cap after the recto was charged gradually as the heater of the GZ34 came up to temperature and this helped to negate any instantaneous current demand on the recto like would have happened if the first cap was after the standby switch. It is interesting that the Komet amps that Ken designed used a single 80uf.

Finally, another tidbit... Malou on Dave Funks amp site... a real nice looking Rocket... is it a real Trainwreck? Can anyone see the mounting screws for the PS board and tell us if it is the Liverpool design?
http://www.thunderfunk.com/In_Performance.html

rj

The picture on Dave's site is misleading. He shows you two pictures of the real Rocket Malou from the outside and then a gut shot of an amp that is clearly a real Liverpool preamp board and NOT a Rocket preamp board. The Rocket only has 4 controls, not 5 like the one pictured, and the preamp board is the wrong layout for a Rocket.

[Ron Worley]

I've seen real flea clips in many surplus places, so I don't think that they are the real long pole in the tent..

Real or decent repro perf board is another matter, I think....

[gearhead]

Flea clips of the right size? Took me forever to get 100. Like to know where you are looking GC Electronics (Calectro) also made some that look a lot like Kens.

The perfboard is the long pole in the tent, that's for sure. You can find 1/16 in the right size for the PS board, but the preamp board is too long. Do a search on UR12 posts from 06 and you'll find he went to some of the manufacturers, who won't do it anymore. That's why he has been making them (in limited quantities).

The original Express boards were actually 3/32, but that's nigh near impossible to find in any size. https://tubeamparchive.com/viewtopic.ph ... hlight=093

[RJ Guitars]

Hello Forum,

There has been reasonably strong reception of my proposed "Group Build" of a Rocket... The idea is that neither myself nor any other forum member builds these for profit, but rather as a group project. The group build allows us some buying leverage in addition to some shared experience and build info.

I intend to disseminate all the learned info to the forum including the vendor information, although some of it may not be available until after the "First Option" closes... possibly even later than that if there are negotiations ongoing with the vendors.

Included in that strong reception I have received commitments for reduced pricing for chassis, boards, faceplates, and transformers. The initial price quotes on everything has been extremely good - more on that later.

The chassis and board sets will be available to me in increments of 6, with 12 being the minimum order. I've already committed to the minimum purchase and those will be made available on a "First Option" list. I'm stuck with them if we don't get enough interest... but I'm not worried about that. If the interest goes above a dozen we will all share in quantity discount savings... this can lead to a very reasonable total build cost.

In the rare event that there is too much interest, I'll probably close the first option list and reopen it later for a 2nd wave... I doubt that will be a problem.

Details will be forthcoming... I'll keep updating the circuit board and chassis design info as we go (see the original post entry for this thread). I'll add another post later that more specifically states what we will build, but the general idea will loosely follow the old Mark Abbott / Matt Taylor posts and schematics. Here is a must read for all interested parties: https://tubeamparchive.com/viewtopic.php?t=23 wow look at that post number!


For those that want to get on the first option list send me a PM. I'll keep the "First Option" list open for now and will post a note on this thread indicating when I need to close it.

I will not ask for or accept any cash commitments or payment until I have actual chassis images for you. Once the process begins I will come up with some reasonable time frame to exercise the "First Option".

The first run of chassis is expected to be complete in about three weeks. I expect it will take awhile to get everything together after that so this should give you an initial time-line on things.

rj

[RJ Guitars]

Hello Trainwreck forum

I have completed the ROCKET circuit board drawings and they are in production now.

The machine shop has the metal in hand and is waiting on me to finish the design specs and they will go to work on the chassis fabrication as soon as I get them the drawings. I asked them for 12 chassis & board sets for the initial order.

For the potential builders as well as the veterans, below is a CAD drawing showing four different layouts - mostly variations on the power supply configuration. Since we do not have any real record of what a ROCKET power supply looks like, these are just a general guide and a look at some options we have.

With the circuit boards that are in production, you can build a ROCKET with our ongoing group build in any one of these four configurations. The tube sockets, transformer mounting options, and main board are identical for all four layouts.

I have not made any attempt to verify or optimize the wiring lead dress that is on the images... or in most cases that is not on the images.

In all cases I have allowed enough room for those over-sized Blue Sprague caps. There are numerous optional cap choices that are substantially smaller. Using chassis mounted can caps is also an option although I did not make a drawing of it.

I hope to get everything finalized in the next two days to allow me to turn the final chassis drawings in to the machine shop.

Has anybody got some additional discussion to bring up with regards to the layout options before I finalize and submit the chassis drawings?

A discussion on transformers is forthcoming.

rj

[RJ Guitars]

Hello Trainwreck Discussion forum,

I've been studying old posts and talking with vendors about transformers for a ROCKET amp. I'll throw out a few tidbits of info that I gathered. You can consider them all and then decide for yourself what you think is true and or worthwhile.

As near as I can understand KF used a variety of transformers and seldom if ever had a standard. This was confirmed by Patrick at Mercury Magnetics, he gave me a great quote - "Every amp Ken Fisher made was different than the last. He used a lot of different transformers including some that he took out of old televisions".

There is some evidence that the STANCOR A-3801 was among his favorite output transformers. https://tubeamparchive.com/viewtopic.php?t=347

The Pacific Power transformer at 250-0-250 was apparently used in a lot of the TW builds.

Heyboer apparently worked with Ken and made transformers for him. The current TW Tranny sets that Moose sells are highly regarded as a similar match to those old KF spec trannies. Moose has added an option 5.2K tap to the 6.6K tap on the OPT that makes them even more useful.
https://tubeamparchive.com/viewtopic.php?t=315

Tubedogsmith suggested that a 35 Watt DYNACO tranny was "THE transformer" or maybe consider an AC 30 OPT if you want an earlier breakup.

Patrick from Mercury Magnetics suggested the MM TubeClone - Radiospares Deluxe - O45RS-L. This comes with the MM "Tone Guarantee"... if you don't cut the leads and you don't like it, you can return it within 30 days or something like that. The MM 045RS-L sounds like a killer tranny, but they are really expensive... rats!

So for this ROCKET Group build I've called all the major vendors and talked transformers. I sent PM's off to the historical Rocket building gurus... they all were very kind to answer. I even tried to cook up a deal with Edcor. Edcor is highly revered in the HiFi builders circle and they gave me a great quote for custom wound trannies... it's just that their trannies are too big to fit the Rocket Chassis.

So in the end - there are many choices. For the current ROCKET Group build the Heyboers fit nicely, they have a great performance record and they are available at a reasonable price.

I am expecting a note back and quotes on a couple other options.

Below is a look at the Heyboer fit into the ROCKET Group Build chassis. Does anyone have another option we should look at?

rj

[Sven]

Greetings,

Thanks for your effort, looks good. But, are you going to draw and post the schematics for this build? That would certainly be helpful, since there are several schematics on this forum and it would be best if we had your final choice of ckt. drawn nicely, so that we have the reference.

I also draw in CAD, but when transfering to other formats, as presented here in .jpeg picture, letters and numbers should be larger and more legible (you really don not need to ¨hatch¨ the resistors and caps, since hatching them messes up the numbers representing the values.

Choice of Heyboer or Dynaco OT is good, most likely (I bought two sets of PT/OT/Choke from Heyboer already for some other builds).

Also, although I am not an expert on TW, your top right corner layout would be the one I would pick (no engineering, experience-knowledge reason, merely a gut feeling that it looks most elegant).

Sven

[Fischerman]

AFAIK, the Moose, Heyboer, Mojotone, and the ones Paul Ruby sells are all the same trannies. The wire colors might be different and some might not even have leads for multiple secondaries but that doesn't mean the windings are not the same. I know for sure the Mojotone are Heyboers because I've bought both and they are identical (the Heyboers for about half the price).

Patrick from Mercury Magnetics suggested the MM TubeClone - Radiospares Deluxe - O45RS-L.

Is that a JTM45 OT? FWIW, I have a 2xEL34 cathode-bias amp that I built that uses Heyboer trannies and I'm using a version of their JTM45 OT. A 'real' JTM45 OT has separate windings in the secondary (not a single 'tapped' winding like we usually use) and there are some other unused windings (like maybe a 70v or 100v winding that I think is for PA use). There are also several different primary impedances...I think 6.6K, 8K, and another one even higher...maybe 9K. There may even be UL taps on the primary (mine has that but I decided I preferred it 'regular').
I just checked their data sheet here and it looks like this OT has all that. EDIT: It's kind of a PITA to have selectable speaker loads with this OT...having the choice of 4, 8 and 16 is a REAL PITA...but if you just choose two output Z's it can be done with a switch (not a rotary one like we usually use but a 2-position toggle that has several poles and throws...KOC mentions how to do it in one of his TUT books).

The PT on my amp above is supposedly good for 300mA and I can't remember the voltage but my amp runs at about 390vdc and ~72mA per power tube with separate 390 ohm cathode resistors. It's a laydown but it might be pretty much the same as their Express PT.

What is the primary Z typically used in Rockets? Is it the 5.2k or the 6.6k? And what is the primary Z an AC30 OT...isn't that closer to 4k?

[Lonely Raven]

I got your address, RJ, and the sample faceplate is on it's way!

[img233]http://lonelyraven.zenfolio.com/img/v1/p31792728-5.jpg[/img]

[RJ Guitars]

I got your address, RJ, and the sample faceplate is on it's way!

That is cool dude!!!

thanks for the great work!

rj

[nickt]

I got your address, RJ, and the sample faceplate is on it's way!

[img233]http://lonelyraven.zenfolio.com/img/v1/p31792728-5.jpg[/img]

Just a nit - shouldn't that be V T B C for the Rocket?

[Fischerman]

RJ,
Would it be possible to have the chassis drilled for the bright switch? I was looking at the schematic and saw the 100pF bright cap and I'm almost certain I'll want to be able to switch it out (I'll probably use a 3-position switch for 2 different cap values plus no cap at all). If people don't want a bright switch they can just cover it up with the faceplate.

EDIT: Found this short review of the RS OT vs. a Woden clone in an AC30.

[Lonely Raven]

I got your address, RJ, and the sample faceplate is on it's way!

[img233]http://lonelyraven.zenfolio.com/img/v1/p31792728-5.jpg[/img]

Just a nit - shouldn't that be V T B C for the Rocket?

I have no idea honestly. I've been so busy with work, and moving into the new house...I simply took my Allyn template and adjusted it for the RockIt drawing that RJ sent me. I've never seen a real rocket, not even in a photo.

I know information is scarce, but if someone can drum up a photo, I'll do my best to replicate it. The faceplate above is just for sizing up to the chassis anyways, so no worries.

[Ron Worley]

Eric-

Nik is right on the controls, I looked at the TW "Brochure" on the "Official TW site"....

Surely there is someone on this forum who knows what the PS board looks like- it would be nice so that RJ can offer a complete board set that is accurate.....

Ron