Audio PA construction.

[VK3ZYZ]

This may be of interest as these transformers are quite easily modded (carefully!).

For a PA I'm building for my wife to use in her singing gigs, I needed a 22V transformer but the 200KVA toroidal one found was 25V.
Red - Black 25V.
White - Orange 25V.
So, or course, it was modded!

First, using a razor blade to poke through the enamel, I tested the continuity to find the winding, then measuring the voltage, a turn from each winding was found that gives 22.4V no load.
A further test with the new red and white wires joined, the voltages across Red to White = a few mV that could be noise, as was the volts between Black to Orange.

A bit of hot melt for strength.

Next will be testing it into the amp.
This amp will drive 2 speakers for the main sound.

Then, doing it again for the other amp that will be for fold back.
This is the mixer to be used.

To be continued.....

 

[VK3ZYZ]

The transformer mod works

Here is the full test

 

[BillC]

All the best stuff is built in the Kitchen / Dining room.

 

[VK3ZYZ]

This is the rear view of the amp case. This case will also be used to hold the leads and mics and the mixer will sit on it when in use.
I got one of the input XLR connectors a bit crooked but it will work ok.
These may be a small fan and vent added in the side of the case to help cool the amp if needed.

 

[VK3ZYZ]

Here is the amp installed in the case....

There will be a divider and cover installed later so cables and mics can be stored in the case.
Then the system will be set up as below.

It works

 

[BillC]

Neat setup, saves wires running all over the place too.

 

[VK3ZYZ]

I want to put a handle on the back of the speaker boxes but do not want to cut a hole in them to do it.
These handles I have had in my stash for around 50 years!

They are diecast and quite solid. Too good to toss out, so finally they will be put to use.

To fit them I drew up some spacers and 3D printed a couple.

Amazingly, they did fit first try. I normally take a few goes to get the sizes right.

 

[VK3ZYZ]

I'm very pleased with how the handles went on.

And the front..

 

[VK3ZYZ]

It is done!
And, as a bonus, between the original winding end and the tap I added, a rectifier and cap give 4.5V when driving a 5V fan so there is a bit of air flow to help keep the amp cool.
Some 3D printed adapters to mount the fan are added, one with the fan and the other just the exhaust.

And the amp is covered up.