18Watt.com

All that trouble for an amp with no balls

Hi Phil
I'm not sure how ballsy it will be, I'm not a metal head more of a hard rocker, as this is my first attempt of doing it all from scratch I settled on a design that seemed about mid strength with the plan to attack it later with the soldering iron later if need be. I have actually never heard an 18 watter in the flesh as pathetic as that sounds.
Have completed the drawings for the graphics and lasered a test run moving forward steadily.

I have just about completed wiring the chassis ready to drop the turret board in and marry it all up.
My question is, how important is the routing of the wiring from the input jacks to V1 Ive seen pictures of neatly routed around the turret board, unceremoniously draped across the top of the turret board and simply laying under the board. I am trying to route these cables around the end of the turret board but am not sure if this is strictly necessary it would certainly be easier to go under the turret board
I am using Mogami w2333 shielded interconnect cable

Ideally, the wiring from the input jacks to V1 should be kept as short as possible, to prevent picking up stray noise. Use of shielded wire would also be recomended.

In the famous words of Rolf Harris, "tie me kangaroo down, sport"

Thank you Phil, my question is will going over or under the turret board cause additional noise? I am using shielded cable I just do not know how important it is to route the cable around the turret board as shown in the layout, or as you suggest keeping it short which would be straight over or under the turret board, going around would be a little trickier but not an insurmountable problem
Tim

AussieTim wrote: ↑

Thu 03/17/22 7:14 pm

Thank you Phil, my question is will going over or under the turret board cause additional noise? I am using shielded cable I just do not know how important it is to route the cable around the turret board as shown in the layout, or as you suggest keeping it short which would be straight over or under the turret board, going around would be a little trickier but not an insurmountable problem
Tim

It doesn't make any difference when it's shielded wire ... over or under. I always run mine crossing under the board. For the sake of avoiding soldering burns when troubleshooting.

Thank you for that I have decided to route them under the board, will post progress photos in a few days

AussieTim wrote: ↑

Sun 09/26/21 8:43 am

Hi Phil
I'm not sure how ballsy it will be, I'm not a metal head more of a hard rocker

To make things clearer, I think the SIII is better suited to rockabilly than hard rock. So I recommend you instead build a Trinity TMB 18W or maybe a Trinity Plexi18W.

The main difference between the Plexi and the Siii seems to be a couple of capacitor positions and values and resistor values early in the circuit, as I said before, when I fire the thing up if it isn't as ballsy as I would like I am happy to attack it with a soldering iron and see where that goes

Just at that point myself Tim reworking my 6V6 amp into a new chassis,going to run the 3 shielded wires under the board and I sourced some ceramic stand off turrets so I can swap out resistors without having to redo the shielding.

Hi Guys Getting closer to finishing this thing, I just about have the chassis and its attached wires sockets and switches pots etc complete. Here are some photos I would appreciate any constructive criticism, The turret board is complete as per previous photos next step is to marry it all together
Tim

Hello Tim,
It looks like you have the rectifier,bulb and filaments feeding off the 1amp 6.3V taps! the ez81 alone draws 1 amp of current so I would use the 3 amp 6.3V taps for the valve filaments and bulb supply.

geoff 1965 wrote: ↑

Mon 04/25/22 11:11 am

Hello Tim,
It looks like you have the rectifier,bulb and filaments feeding off the 1amp 6.3V taps! the ez81 alone draws 1 amp of current so I would use the 3 amp 6.3V taps for the valve filaments and bulb supply.

Nice catch Geoff!

Thanks guys

Don’t forget to ground the 3 amp 6.3V centre tap along with the 290 HT centre tap and the screen SCN to the ground of your can capacitor. You could add a 2W 220K resistor between the first filter of the can cap and ground to bleed off the voltage for safety.

Hi Guys
Just wondering, I drilled the holes for some carling switches slightly too big.
Do any of you know where to get some nice shiny washers to go around them? I have been searching and cannot find anything I am probably looking in the wrong places, any suggestions?
Tim

AussieTim wrote: ↑

Fri 05/13/22 6:07 am

Hi Guys
Just wondering, I drilled the holes for some carling switches slightly too big.
Do any of you know where to get some nice shiny washers to go around them? I have been searching and cannot find anything I am probably looking in the wrong places, any suggestions?
Tim

I use the 12.4mm ID washers meant for guitar pedals. You can get them from most pedal supply places, but I dunno what's easy to get down undah.

Finally finished wiring this thing up, time to go through it with a fine tooth comb then follow the start up procedures, I know a guy who is a professional amp guy and is happy to help me commission it as has an oscilloscope and a lot of knowledge so I will see him in the next few days
Anyway here are some pictures of what I hope is the completed amp

Hello Tim,
As I mentioned before you need to swap those 6.3V supply’s around,the 1A supply goes to your ez81 and the 3A supply feeds the power and preamp tubes and you need to ground the centre tap of the 3Amp as well.
Good luck