Building a Rocket - Layout Check for group build

[RJ Guitars]

EDIT 6/1

[Fischerman]

Things I noticed:
Don't forget the pilot light from hot-to-neutral...basically in parallel with the PT primary leads.
Wire colors are wrong on the Rectifier socket. The grey leads are the 5vac heaters and go to pins 2 and 8...the green/yellow leads are 260v leads and go to pins 4 and 6. The yellow leads are the 300v taps and are not used unless you want higher voltages (then use the yellow instead of the green/yellow). Just cut and heat-shrink the ends of the yellows and stow them away.
I think it's better to let the first filter charge up while in Standby; then when you flip the Standby switch the OT center tap and choke are connected to the first filter which then fires up the whole amp. I think this is easier on the rectifier...especially if you use the full 80uF at the first filter node. The way you have it wired none of the filter caps are charged until you flip the SB switch and then there's a big inrush to charge the caps...harder on the rectifier. Whether this is really an issue I dunno but I know some of the Vox AC30 reissues have too many rectifier failures due to bad SB switch design (their's is different than yours...they switch/fuse the PT center tap but it's still the big inrush that's the issue). How you decide to do it is up to you. I made extra eyelets on my power board so I could run a twisted pair from the SB switch to the board and then run the choke as a twisted pair terminating adjacent to the SB twisted pair. The OT center tap also has it's own eyelet right there on the power board too...this is all between the first filter and the screen filters on my power board. In the case of the AC30 reissues it's better to just not use the SB switch at all...just leave it ON and let the rectifier come up slowly. We don't really even need a SB switch...I've left mine in the ON position pretty much since I built mine and I just let the rectifier come up slowly.
Is there a reason you chose to 'couple' the power tubes the way you did? I did mine on the same side...i.e. both tubes on the left are one pair with coupled grids/plates and both tubes on the right are the other coupled pair. But you staggered them and I assume it was intentional so I was just curious. I don't know if it matters...it doesn't really matter in an electrical sense but maybe it makes a difference tonally?
Other than it looks good...just make sure you plan all your grounding...it always seems to be an after thought but it's very, very important (it's really where all our electrons are coming from!).

[RJ Guitars]

Things I noticed:
Don't forget the pilot light from hot-to-neutral...basically in parallel with the PT primary leads.
Wire colors are wrong on the Rectifier socket. The grey leads are the 5vac heaters and go to pins 2 and 8...the green/yellow leads are 260v leads and go to pins 4 and 6. The yellow leads are the 300v taps and are not used unless you want higher voltages (then use the yellow instead of the green/yellow). Just cut and heat-shrink the ends of the yellows and stow them away.

I think it's better to let the first filter charge up while in Standby; then when you flip the Standby switch the OT center tap and choke are connected to the first filter which then fires up the whole amp. I think this is easier on the rectifier...especially if you use the full 80uF at the first filter node.

Is there a reason you chose to 'couple' the power tubes the way you did? I did mine on the same side...i.e. both tubes on the left are one pair with coupled grids/plates and both tubes on the right are the other coupled pair. But you staggered them and I assume it was intentional so I was just curious. I don't know if it matters...it doesn't really matter in an electrical sense but maybe it makes a difference tonally?

Other than it looks good...just make sure you plan all your grounding...it always seems to be an after thought but it's very, very important (it's really where all our electrons are coming from!).

Matt - great set of eyes and a real help to the builders who will use this layout.

Pilot light wiring is now shown - everyone note that this requires a 110V light not the old 6.3V Fender style.

Good catch on the yellow wires - I always think of yellow as the official color for 5V - Heyboer is different on that.

I've never done this type of layout on the Standby switch and filtering - did I get it right?

Putting the pairs in order the way I did is not essential - it does make it easier for me to setup the half power switch. I'd listen to anyones argument to revisit that layout since it doesn't lend itself to the two tube options for the future.

O.K. grounding is next. I learned from the HiFi guru's and they like to have only one central ground in the whole amp... What is your school of thought on this.... or the thoughts of any other well informed builder with Trainwreck Savvy.

rj

[Fischerman]

I've never done this type of layout on the Standby switch and filtering - did I get it right?

I think you have the OT center tap on the wrong side of the Standby switch...the power tubes would be running in standby. And the OT center tap and one wire of the choke should be on that same side of the SB switch. You want the first filter cap to get the juice in Standby but you don't want the OT center tap or the choke to get the juice until you flip the SB switch.

Regarding grounding; You need to drill any extra holes for ground bolts now before you get started. I would suggest you look at Expresseses/Liverpools and go with that...and then remember that the ground for the cathode resistor goes to a bolt right near the power tubes.

[Ron Worley]

The standby switch needs to be after the first 2 40uf caps and the bleeders like the Liverpool and Express. The Matt Taylor schematic you updated is wrong. Here's the LP schematic to better explain the point...

Ron

[gregarious]

double

[gregarious]

Good catch on the yellow wires - I always think of yellow as the official color for 5V - Heyboer is different on that.



rj

Sort of curious the inconsistent color coding of transformer flying leads with no standard convention that is universally accepted.

UK manufacturers seem to have avoided this by labeling the PT connections (and saved some coin on wire). OT's are another story.

[Allynmey]

RJ, I feel like a broken record saying this again but...

No power board on a Rocket.
Screens are 100 Ohms.
50 Ohm Cathode.
No 1/2 Power (it does affect the sound).
220uF bypass cap.
Cathode and bypass cap on other side of power tubes bolted to the chassis.

If your goal is a hybrid or your own design...no problem...disregard the post. If your goal is to make a close or perfect Rocket clone, you seem to be straying farther away every day. I think most people who are following the thread think this is a exact clone project so you might want to mention your intentions to them. I'm happy to help with whatever you and everyone else needs to build a correct amp (if that is their intention), so I don't know why the actual values and layout is being ignored.

[RJ Guitars]

RJ, I feel like a broken record saying this again but...

No power board on a Rocket.
Screens are 100 Ohms.
50 Ohm Cathode.
No 1/2 Power (it does affect the sound).
220uF bypass cap.
Cathode and bypass cap on other side of power tubes bolted to the chassis.

If your goal is a hybrid or your own design...no problem...disregard the post. If your goal is to make a close or perfect Rocket clone, you seem to be straying farther away every day. ....

Allyn,

Sorry to make you repeat yourself, your words have not gone unnoticed by me. I especially need to look at those screen resistors.

As presented in my layout iteration above it is definitely a hybrid design with an absolute debt and respect for the original. It can also be built as authentic as a person wants to take it. I really would not want to say either is superior, just different flavors.

Among the amps that I found inspirational were those by Keithrick, Paul Abbott, and Paul Ruby, plus many others. Interestingly, none of those provided a template for a complete authentic Rocket. In fact some were much more hybrid than I have provided the layout for.

At this point following this group build effort I now have a more complete idea of how to put together an authentic Rocket. That info wasn't available to me before the build and while developing our Rocket, we have brought into the public light a solid and relative well authenticated template for a clone.

With the extremely high post count, I hope this means that the group build is a positive for the forum. Looking at the recent posts, there aren't too many that track as high as this project. I have also had so many casual notes of thanks and affirmation of the good will brought forward through this effort. I will not ever be able to individually acknowledge them all.

I know that there is some concern that we may not be paying homage to the authentic Rocket and Trainwreck build. The camps are divided on this and some of the feelings strong. In truth I think the ability for somebody to build an authentic clone is now much more possible than before. Interestingly, with very few exceptions, the folks building the amps have indicated an interest in a hybrid design and the folks showing concern are not building an amp at this time. At the onset I would have gladly gone wither way on this.

Mostly thank you Allyn for picking up the forum management, we are very fortunate to have this resource,

rj

[Lonely Raven]

OK, I'm so very lost at this point. We are going all over the place, and I, as a beginner amp builder am having trouble following all this back and forth. My Rocket parts are arriving on Monday, and I'm not sure where to start...which is going to be a frustration for all the builders who *aren't* at a high level like Matt and Allyn.

Could we please clearly define how to build as much of a *clone* of the Ken Fisher Rocket as possible?

I'm sorry to say that up until Allyn put his fut down, I thought we were sifting through the communal knowledge to put together a Rocket clone!

While a modern rendition of a Rocket is fine by me, it should have been clarified exactly what we are building, and the builders should have enough information to make the choice as to which (clone or hybrid) they want to build. Especially since, as I've said before, I'm lost without a Layout and BOM....and I'm sure I'm not the only one.

So, could we please have clearly defined information for both a Rocket Clone and a Modern Rendition of a Rocket? Maybe start a seperate thread for each so the information doesn't get mixed up as it is now?

I'm sorry if I'm sounding rude...I just believe in the Keep It Simple Stupid method, and we seem to making things more and more difficult...and I'm not smart enough to muddle through difficult.

[Lonely Raven]

Double Post, Sorry.

[UR12]

For the folks who aren't interested in a "Hybrid Design" but one that is closer to a real rocket clone, I offer you a couple of pics of a Rocket board that I cloned from the real thing. The original Rockets were the third in a series and I believe most were built using the later style perfboard and clips. I have transposed the exact layout onto the older style perfboard but that is the only changes from the original made by Ken. Some people have contacted me regarding making them a more authentic preamp board and I must say at this time I have no interest in making these available. If I find time to make some I will offer them here. If somone wants the populated board pictured, The first $60 takes it. (Shoot me a PM) It has 6PS .1uf caps and PVC 6122 (.022uf) caps installed. The unpopulated board is already spoken for. Hopefully this will help you guys to make your own, the small difference between Mark Abbot's board layout and this one is the 100k resistor that Mark has mounted on the tube socket for the CF is actually mounted on the board and the CF is spread out over V1 and V2 triodes, as mentioned by others in this thread.

It will be interesting to see how these "Hybrid designs" stands up aganst a true clone. Personally I would go with the 4.2k tranny also but hey what do I know?

[Lonely Raven]

Dana, Allyn...E-mails sent.

[guitarsnguns04]

I agrre LR..I think we should have the hybrid layout and a clone layout. From there we can choose which way to go and it would shed some light in the way of mods or tweaks as well. I dont particularly care for an exact clone in the way of wire color details etc. But I am very interested in cloning the tone. I am a tweaker and will mod whatever I build to my personal taste anyhow but I beleive what we start with has all the effect on what we end up with. Hopefully it is just a matter of values and layout differnces. I am gettting my parts this week so I will know more when it is in hand. I am sure we can have great results with our builds. Fischerman already has proven that. I would encourage and welcome input from Allyn and Dana if possible to help those of us who have never seen or heard one. It would be appreciated by all I am sure.

[Noel Grassy]

I'm glad to see that there's a revived interest & more willing contributors in making the correct Rocket amp.

I was under the impression that's what this thread's original intention was.


Such arbitrary hybridizing of the original will unfortunately be nothing more than a wankfest in terms of my desires. Of course, I'm not trying to get a product to market either.

The Express, for example, was an excellent way to experience a method of building amps that none of the available books describe. I feel I learned some effective design skills.