JTM50 Build

[michelebis]

nice

 

[Marcomel79]

Hi Marco, I hate to say it but the only long term solution for the turrets is to flare the backs. This can be done quite easily, but you would need to remove the components first. Sorry!

Thank you Andy, i was hoping somebody would talk me out of my idea...

 

[AndyD]

It will be worth it! Sometimes you have to go backwards to go forwards.

 

[pietro.castelli]

I would also agree with Andy. You're doing an amazing layout with that turret board. You don't really want such a nice build to be plagued forever with "loose" turrets. You've done everything on top of the board, and you haven't soldered any component yet, so I think you can still go back and flare the turrets without too much destruction.

 

[Marcomel79]

Thanks guys, only three capacitors are wrapped around the turrets so its no stress. If id had a workshop at my house i would have already done it that way.

 

[Central Scrutinizer]

Glad you discovered it early before everything was soldered in place.

Sometimes you get lucky.

 

[neikeel]

I prefer split turrets and use tight fitting holes and a centre punch with turret tool to keep square.
If you like you can raise a blob of solder on the underside of the board to stop it moving.
How are you finding those solid turrets. The ones I had needed a lot more heat than I usually like.

 

[Marcomel79]

I prefer split turrets and use tight fitting holes and a centre punch with turret tool to keep square.
If you like you can raise a blob of solder on the underside of the board to stop it moving.
How are you finding those solid turrets. The ones I had needed a lot more heat than I usually like.

Hey Neil, the split turrets are really cool, but very expensive compared to the ones from Tube Town. I paid 3.32€ for a bag of 25. I soldered the connections really fast, i didnt think they needed a lot of heat.

The solder blob method is something i thought about, but i dont want to use more heat near the base now, where all the jumper wires are...

Next time ill drill the holes a bit wider so i can push thrm through easily and flare them on the drill press. You live you learn right?

 

[Marcomel79]

Should be good now

 

[AndyD]

Should be good now
View attachment 123469

Agreed!

 

[Marcomel79]

All the components are in place except for three resistors. Hopefully they will come in the mail tomorrow so i can break out the trusty soldering iron. Good night

 

[pietro.castelli]

You made the right decision! The peace of mind from turrets that feel "secure" will last forever.
The board looks awesome! Exquisite attention to detail! Can’t wait to see the full chassis!

 

[Marcomel79]

Yes, from now on, its a must

 

[Marcomel79]

Im calling the experts for a layout question:
Im thinking of following the Modulus layout for my build, as opposed to the schematic,


http://www.marstran.com/JTM50.gif
but i will ground the whole circuit at one point only, by the input jacks. Whats the verdict?

 

[neikeel]

The schematic is wrong anyway (sorry Brian!). The HT is incorrect. I’ve experimented a bit with grounding and use a modified Larry Grounding scheme.
1) input jacks, vol pots, v1 cathode and heater CT at the front corner by jacks.
2)Tone stack, v2 cathode and preamp can on choke bolt.
3) bias caps, octals and output jacks on octal socket ground
4) presence and pi cap and screen cap on chassis by cap.
5) Mains and ht Ct (fused) on rectifier.
I’ve used central ground before but you have to be careful not to double up a ground and get a ground loop.

 

[Marcomel79]

The schematic is wrong anyway (sorry Brian!). The HT is incorrect. I’ve experimented a bit with grounding and use a modified Larry Grounding scheme.
1) input jacks, vol pots, v1 cathode and heater CT at the front corner by jacks.
2)Tone stack, v2 cathode and preamp can on choke bolt.
3) bias caps, octals and output jacks on octal socket ground
4) presence and pi cap and screen cap on chassis by cap.
5) Mains and ht Ct (fused) on rectifier.
I’ve used central ground before but you have to be careful not to double up a ground and get a ground loop.

Thank you Neil for the nice explanation. I was just thinking of dividing into two grounds, preamp ground and all the rest. Both grounded by the input jacks. Ive used central ground in 5 builds so far, and all of them are dead quiet, thats why im leaning that way..

Now you got me thinking....

 

[pietro.castelli]

If you are after the reduction of the noise floor, you might also consider improving the heater wires routing, which, in marshall circuits, traditionally loop around the tube sockets crossing some of the preamp signal wires.
Some people switch to a "fender style" routing with heater wires passing through the pin sockets.

 

[Marcomel79]

If you are after the reduction of the noise floor, you might also consider improving the heater wires routing, which, in marshall circuits, traditionally loop around the tube sockets crossing some of the preamp signal wires.
Some people switch to a "fender style" routing with heater wires passing through the pin sockets.

Hey Pietro this is how im gonna do the heaters, all of my builds used this style. Picture stolen from @Pete Farrington

 

[Central Scrutinizer]

@Marcomel79 , you will get this figured out!

You have some very knowledgeable members giving you great advice.

Good luck!

 

[pietro.castelli]

That's exactly what I was referring too!