firezog schematic?

[strangerock]

hello,
does anyone know where i can find a schematic for doug h's firezog?
the link i found doesn't seem to work.
thank you
sr

[d95err]

It's extremely simple. Connect a pot just like a regular volume control from the speaker output to ground, and add a series resistor from the wiper. Take the line output from the series resistor.

The value of the pot and resistor is not that important. The original Firezog suggests an 1Meg pot and a 100k series resistor. A lower value should result in lower output impedance and noice (I think). I use a 4.7k pot and series resistor on my 15W amp.

Like this:

Code Select Expand


SPEAKER OUT
   |
   |
   N
   N<---NNNN---LINE OUT
   N
   |
   |
  GND


One more thing. If it's a tube amp, you need to connect a dummy load if the speaker is not plugged in. The dummy load resistor should have the same resistance as the corresponding speaker impedance (e.g. 8 ohm resistor for an 8 ohm speaker). It should also have a power rating of at least twice the power of the amp. The power resistor must be properly heatsinked and attached to the amp chassis.

With a regular switching jack, you can easily have the dummy load switched in automatically when you remove the speaker cable.

[strangerock]

thank you.
much appreciated.

[Pushtone]

An older version of Doug H's web site, including the Firezog.

...could be out of date, but it's all that left.

http://web.archive.org/web/20050212085405/home.cfl.rr.com/dbhammond/doug.htm





Good luck and all the best to Doug in his new ventures.
Can someone send me the HWY-89 schem 

[John Lyons]

Just search for Basicaudio and Hwy 89. I posted it im my build report. Maybe it should go in the gallery. I guess I should put up a gallery as well.  Email me if you can'r find it.

John