Trainwreck Rocket AC30-ish build NOW WITH REVERB

Keefy · April 2020

PeteC said:

Nice.....Are you going with a turret style board or eyelets, and are you going to try replicate the lead dress or going with your own layout ?

Cant wait to see the build progress. Great to see the attention to the metalwork which will make it a fine looking finished amp - something I have a tendency to rush tbh.

I'm going with turrets - I already have a staking tool for fixing the turrets into the board. The layout is based on the Modulus Wrocket 30 layout, albeit some of my components will be in different locations. I am going to take the pre-amp and power amp earths to different points on the chassis as per Rob Robinette's scheme, which is what I did when I built my Modulus 5E3.

I wouldn't get too excited about my metalwork mind - any bodgery will be covered up by plastic facing. The panel with all the masking tape on will be the front, but used to be the back. I'll have to drill extra holes for 3 pots, the input socket, and the pilot lamp. The old mains inlet cutout and two of the existing holes will be covered by facing.

ICBM · April 2020

If you haven't drilled it yet, I think I have the correct fused IEC socket - or you can buy them online. It will do a better and safer job than having to cover the hole for the original one.

If you have drilled it already, you could make it for a HT fuseholder.

Keefy · April 2020

ICBM said:

If you haven't drilled it yet, I think I have the correct fused IEC socket - or you can buy them online. It will do a better and safer job than having to cover the hole for the original one.

If you have drilled it already, you could make it for a HT fuseholder.

I have the fused IEC socket that came out of that hole but I don't fancy trying to cut a square hole in 14-gauge steel in the new back panel (which used to be the front panel). Mains will come in via a captive cable secured by a strain-relief grommet in the bottom of the chassis tray, and there will be mains fuse and HT fuse-holders on the rear panel. Hope that make sense!

Keefy · April 2020

Modulus order has arrived!

Image: https://i.imgur.com/LSe37mi.jpg?1

PeteC · April 2020

Always great when parts turn up. What are you using for a faceplate/ are you getting your faceplate laser etched ? Whenever I’ve made custom amps out of old chassis I have always found getting custom faceplates very expensive.

Keefy · April 2020

PeteC said:

Always great when parts turn up. What are you using for a faceplate/ are you getting your faceplate laser etched ? Whenever I’ve made custom amps out of old chassis I have always found getting custom faceplates very expensive.

For the moment I will be using burgundy-coloured 0.8mm polypropylene sheet, which I will be fixing to the front and rear chassis surfaces with contact adhesive. I used black sheet (together with a label printer) on this rack-mount spring reverb build:

PeteC · April 2020

Good solution I'm lucky this time that I can use a very simple engraved wood faceplate on my express attempt.

I'm really looking forward to seeing how your build turns out - I bought a mains TX for the express that will do for the Liverpool/Rocket as well if I decide to change the amp. Suspect I might have some stability issues as I am using a steel chassis rather than Ali - but we will see.

The rocket clips I have come across sound great - really chimes cleans, and crunch.
Good luck with assembling.

Keefy · April 2020

PeteC said:

..

Suspect I might have some stability issues as I am using a steel chassis rather than Ali - but we will see.

...

Are we talking mechanical or electro-magnetic stability? My chassis is steel, but the transformers are in the same position as in the donor amp. The only extra iron will be the choke.

PeteC · April 2020

electromagnetic - lots of posts on Ampgarage and the like about Ken Fischer only using Aluminium to prevent magnetic effects through the chassis.

Iv'e done quite a few amps both ways and never had any issues - but the Express circuit is reportedly such a high gain and temperamental beast that it might concevenably be an issue - I dont really know tbh....

I don't think the rocket will have as much of an issue anyway.

Keefy · April 2020

PeteC said:

electromagnetic - lots of posts on Ampgarage and the like about Ken Fischer only using Aluminium to prevent magnetic effects through the chassis.

Iv'e done quite a few amps both ways and never had any issues - but the Express circuit is reportedly such a high gain and temperamental beast that it might concevenably be an issue - I dont really know tbh....

I don't think the rocket will have as much of an issue anyway.

Cheers for that, yes I think I read that the Rocket is lower gain than the Liverpool.

Keefy · April 2020

Turret board is marked out for holes to be drilled. I thought it might come with 2 rows already drilled, but this will actually make it look more bespoke and less generic. Also the piece of board is a little longer than the original layout requires, so I have space to fit my rectifier diodes rather than mount them on a separate tag board.

Keefy · April 2020

This weekend I have mainly been drilling holes in the chassis, and replacing T-nuts.

All the chassis holes are now drilled so I can start assembling hardware to the chassis. I had to add a pair of mounting holes for each valve, which took some careful trigonometry. If I get as far as adding reverb then there will be a couple more holes to drill, but I'm good for now. One alarming moment occurred when I was enlarging a hole to accommodate a strain relief grommet for the mains cable, and realised the grommets I had just received could fit through without touching the sides. On closer inspection I realised I had been sent the wrong size.

In my donor cabinet, the speaker and its baffle are both secured by T-nuts. I had no speaker bolts, the existing baffle bolts were rusted to hell, and the T-nuts (black/rusted) were an unknown imperial size. I replaced them with M4 T-nuts (silver coloured in the phots) and re-fitted the baffle. More M4 bolts are incoming for the speaker itself.

Keefy · April 2020

Re-mounted the transformers onto the chassis and added the choke. Installed all the valve sockets, with spring retainers for the power valves and shielding cans for the pre-amp valves. Mounted the cathode resistor to the chassis with a bit of heatsink compound for good measure. I can't add much more to the chassis until I've made and fitted the facing.s, as things like the fuse holders and pilot lamp install from outside and are then soldered in place.

Next job will be to drill and stake the turret board

Image: https://i.imgur.com/Rsjudq4.jpg?1

Image: https://i.imgur.com/W6p4u54.jpg?1

Keefy · May 2020

Turret board drilled, staked, and populated. Also did a test fit into the chassis - there's a lot more space to work in than in a 5E3 chassis! Still have to add wire links and runners, then out comes the soldering iron.

PeteC · May 2020

Looking great ! Nice work

Keefy · May 2020

PeteC said:

Looking great ! Nice work

Cheers! I’ll cherish your kind comment when I eventually switch it on and see the magic smoke come out...

JMP220478 · May 2020

Keefy said:

PeteC said:

Looking great ! Nice work

Cheers! I’ll cherish your kind comment when I eventually switch it on and see the magic smoke come out...

great idea - built in smoke machine ... very spinal T ... :-)

Keefy · May 2020

All solid-core wire links above and below the board now completed. Although it is arguably easier to fit the under-board links before the components, it is much easier to verify that you are fitting the links in the right places once the components are in situ. In the process of doing all this I found and corrected a layout error that would have stopped the Cut control from working. I will come back to the board in the morning, check it again, and then solder any turrets that won't have off-board leads connected to them.

In related news I scored a Creamback Neo to use with this amp - should be a decent match, and the reduced weight will offset the addition of 952g of choke!

Keefy · May 2020

New faceplate material in place, glue setting.

PeteC · May 2020

keep em coming - can't wait to see it finished/fired up !

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Trainwreck Rocket AC30-ish build NOW WITH REVERB

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