A15 help

Re: A15 help

If you play softer blues and rock you would probably get away with an M15Mk1 and there is already a footswitch circuit on here for that amp that works well.

This company do speaker cabinets and head cabinets that will fit Martins amps (I believe - haven't tried them myself yet but was going to get one to go with the next amp).
Speaker cabs: http://www.tubetown.de/ttstore/index.…eaker-Caps.html
Head cabinets: http://www.tubetown.de/ttstore/index.…sis---Kits.html

Celestion speakers website has a good page for speaker wiring for various combinations of speaker: http://professional.celestion.com/guitar/feature…secret_swd.html

I can't answer the line out question though but there is an optional send/return circuit for the M15Mk1 but my electronics isn't good enough to tell you whether that is compatible with what the PA is expecting.

Good luck - search around for the cabs though as you may find somewhere closer to home.

Re: A15 help

Zitat von royboy

maybe a poti parallel on the the out put so I can ajust what goes to the PA. As far as the ls and head box I don't see to much of a problem with making them myself (build a amp so the rest must be hand made, want something original ) Wish me luck!!

I don't know exactly what you mean by a "pot in parallel on the output", but if you do it wrong you could burn the amp AND the PA. Be very careful!

When using a line out, you always need to have a speaker or dummy load connected, or you risk frying the output transformer. The Madamp amps have a safety resistor across the speaker out, but I wouldn't rely on it saving the output transformer for longer periods.

If you look at some Matchless amps, you can see how to wire a line out that will probably work with an A15. They use a 22k resistor from the speaker out and then a 3k3 resistor to ground.
Schematic: https://schematicheavencom.secure.powweb.com/newamps/matchless_spitfire.pdf

Note that the line out signal by itself will sound utterly crap if you connect it directly to a PA. You need some kind of speaker simulation to make it the line level signal sound good.

There is also a risk of ground loops when connecting the line out to a PA (i.e. lots of hum). You may need to isolate the signal using a buffer or transformer to break the ground loop.

A simple (but not DIY) solution is to get something like the Behringer GI-100. It's an active direct box with built-in speaker simulation. You can connect it between the amp and the speaker witout having to use a line out.

I intend to implement a line out on the M15Mk1 I'm building. Possibly a built-in speaker simulator as well. I'll let you know how it turns out.