Output Tranformer Ground Soldered to Frame

[hack]

Ideally, should this be cut loose, solder a lead and connect it to the speaker jacks, then on to the quiet ground lug for the preamp side I made near the input jacks?

Or, will it be quiet enough if left as it is?

In that case, I would ground the isolated speaker jacks via said lead to the preamp ground lug.

[Bruce / Mission Amps]

Use some star washers under the OT channel mount, so it digs into the chassis and the channel mount... plus use a couple star washers under the heads or nuts you clamp the OT to the chassis.
Use a good star washer on your output jacks too... I'm pretty sure it will be just fine.

[R.G.]

As with all questions about grounding, one should ask one's self: what currents flow through what conductors, and to where? Answering that question contains all of the solutions to all grounding problems.

[Randall]

Is anyone else uncomfortable with the fact that if a speaker jack nut goes a bit loose, you have a faulty speaker connection along with the perils that brings? Seems like a bad idea, why not run wires to the jacks?

[Tom Phillips]

Ideally, should this be cut loose, solder a lead and connect it to the speaker jacks, then on to the quiet ground lug for the preamp side I made near the input jacks?
Or, will it be quiet enough if left as it is?
In that case, I would ground the isolated speaker jacks via said lead to the preamp ground lug.

For most simple amps it’s probably quite enough as is. However, if I were going for the best topology I would unsolder the wire from the OT frame and run it to the negative lug on the speaker jack. I would also isolate the speaker jack ground from the chassis and make an additional connection from the speaker jack negative lug to the point where the phase inverter is grounded. I would not ground the speaker jack to the input jack.

Note that sometimes when you make one "improvement" to a grounding scheme the overall performance can actually get worse. This is because the circuit is a system composed of many different connections. Sometimes one less than ideal thing compensates for another. In that case you need to change more than one part of the circuit to make an overall improvement. Hope that makes sense.

Is anyone else uncomfortable with the fact that if a speaker jack nut goes a bit loose, you have a faulty speaker connection along with the perils that brings? Seems like a bad idea, why not run wires to the jacks?

That is something to be aware of but I’m not too concerned personally. I just consider tightening (and sometimes cleaning) all the mechanical grounds in an amp as part of periodic maintenance. The old Fenders have many mechanical ground points.


Regards,
Tom