Brake Lite or ......

[beakos]

I'm thinking of building a Dr Z Brake Lite style of attenuator for my little Marshall.

Based on the info found here, it seems the Trainwreck AirBrake and Brake Lite are 'birds of a feather' with the difference being the AB has a reheostat for bedroom levels.

I was looking some other places and came up with a different schmatic that seems to be similar in concept to the AB / BL. I've attached the link below.

Two questions:

How close is the attached link to the AB / BL. Will this one sound the same as the AB / BL?

Second - From everything I've read, the AB / BL is designed for an 8 ohm amp output. What would I need to change to work properly with a 16 ohm amp. Or a 4 ohm?

Thanks!!

http://www.hearditontheweb.com/images/p ... nuator.pdf

[surfsup]

I built something similar to the airbrake. The concept is to put a resistor in series and in parallel with the speaker. By adjusting the values of the resistance, you can change the attenuation of the signal to the speaker. The problem is matching the impedance of the speaker. If you want to be at 8ohms resistance to the amp (as though there was only a 8ohm speaker attached), you can't just change the resistances to any arbitrary value. You will need to figure out what combination of resistance in series with the speaker, in parallel with the shunt resistor to ground, will still keep it all at about 8ohms, while simultaneously attenuating your signal with two paths to ground (only one having your speaker producing noise, the other producing heat).

This is how I thought of it, and it could be wrong, but mine turned out to work very well.

I also did not use a rheostat, either, as well as making the last rotary position a silent dummy load to use for testing purposes.