Variable DI-Out

One feature which I really wanted to add to my amp to increase the versatility is a DI Output.

I was recently looking at the circuit diagram to a Mesa Boogie Studio .22 Caliber Plus, in order to replace the power supply capacitors for a friend and noticed that it had a really simple DI output with variable level. So using this as a basis, I came up modified my amp as follows:

Changes highlighted in red.

I've seen some other mods out there to add DI outputs to similar amps that suggest taking the output from between the pre-amp stage and power amp stage, but the advantage of this mod is that since it's right at the end of the signal chain, it should sound exactly the same as the signal that reaches your cab... and I'm pleased to say that it works and sounds great :)

Speakon Speaker Connectors

The first mod which I wanted to carry out, is to add Speakon connectors for a better connection to my cab.

This is a very simple mod with the following circuit diagram:

To see the differences between this circuit and the original, see the the original circuit diagram in this post: Vanilla

By connecting the positive inputs to the speakon sockets to pin 2 of the jack sockets, the speakon sockets will only be connected if a plug isn't inserted into the jack socket. This helps to prevent the eventuality of a speaker being plugged into both the jack and speakon socket being connected at the same time which could lead to an accidental impedance mismatch.

Update 25/11/2009:

Highlighted the changes in Red to make them more obvious.

Vanilla

2 weeks ago I received my order from Ampmaker - a PP-18 full valve, push-pull amplifier.

After 2 evenings work, it was finished and working nicely. Except that the tone stack wasn't ideal for bass guitar, which is what I will be using it for, so I started thinking about alternative tone stacks which I could use... and this led me to think of a number of modifications and customisations which I intend to carry out.

Over the coming weeks and months, I will post these modifications on here as I complete them and check that they work as expected. I'll also be posting photos of my amp in it's various stages of completion.

For now, here is the original circuit diagram and a link to Ampmaker should you want to purchase your own. I can highly recommend Ampmaker particularly since Barry, the owner of Ampmaker, has been incredibly helpful in discussing these ideas with me since my purchase.

Ampmaker