OK, well it's a been a little while, but I have finally gottten round to replacing the capacitors and resistor in the DM3 crossovers.
I used Jantzen standard caps for the woofer and tweeter, their cross-caps for the super-tweeter, and their superes 10W resistor.
I decided against any higher quality caps for the high frequencies, as being hearing impaired, I didn't feel the juice was worth squeeze, but even I have immediately noticed a crispening of the soundstage, a lifting of a veil I had not even been aware of.
The original, ITT, capacitors were not too far out of spec, but were clearly tired.
The 6x2.2uF caps measured 2.25, 2.25, 2.25, 2.17, 2.10 and 2.16
The 1.5uF caps measured 1.587 and 1.53
The 0.68uF caps measured 0.751 and 0.753
The resistors both had some heat stress damage, so I replaced them both.
I decided not to mess with either the orientation of the inductors, nor the iron core on the woofer circuit, as looking at the original frequency response being so flat, I am wondering if the XO was not possibly designed with the orientation accounted for?
Anyway, eitherway, they really are incredible fun to listen to, and I am thinking I would like to install tube connectors and replace the internal wiring. With this in mind, I would be grateful of some advice on how to connect the internal end of the tube connector to the circuit board.
The connection is currently via a biding post which is itself non-ferrous, but has a ferrous disk at its midpoint, which holds it to the backplate. This bolt fits through a hole in the circuitboard, and is connected to the circuit by being sandwiched between two non-ferrous washers. This would seem to be an obvious place for improvement in the signal path, but am wondering if drilling holes for the tube connectors in the cabinet, below the binding post plate, and soldering short jumper cables between the tube connector and the circuit board?
I'm thinking of also replacing the internal wiring, and doing away with the (non-ferrous) connection between the baffle and the cross over.
Would it be very detrimental to put the tube connectors near the bottom of the speaker, but keep the cross over in the original position and connect using a long piece of wire?
Any advice much appreciated.
Here a vid of where I am
https://youtube.com/shorts/KeAowQ3Gy58