Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: plexi50 on July 23, 2010, 02:25:46 pm

Title: Line Out For Mixer Board
Post by: plexi50 on July 23, 2010, 02:25:46 pm

Can i feed a mixer board a signal  from the PI of an amp to the mixer board

Title: Re: Line Out For Mixer Board
Post by: RicharD on July 23, 2010, 03:38:12 pm

Are you trying to grab a differential output from the PI and feed into the snake?  You could by using a pair of isolation caps but it's gonna load the PI and affect what the output tubes see + the impedance is quite high.  I'm a believer that the best way is to add a speaker tap.  Embellish this to match your amp.  Add a matching transformer (DI box) to get it balanced.  Theoretically now the mixer is seeing what your speaker is seeing.

(http://www.dairiki.org/hammond/pics/m3-line-out.gif)
Typical Hammond organ mod.

Title: Re: Line Out For Mixer Board
Post by: plexi50 on July 23, 2010, 07:46:38 pm

I tried this a while ago tonight and it worked for a minute until the pot started to smoke. I did not use a 10 watt resistor across the green and black speaker feed. What am i doing wrong?

Title: Re: Line Out For Mixer Board
Post by: RicharD on July 23, 2010, 08:55:19 pm

No.  That's a speaker or a dummy load.  This circuit is for a little old 10ish watt Hammond Organ amp.  That will smoke a 1/2W pot for certain if you're using a 50W amp.  This looks considerably more correct.

(http://www.tkk.fi/Misc/Electronics/circuits/speaker_to_line.gif)

http://www.tkk.fi/Misc/Electronics/circuits/speaker_to_line.html

Title: Re: Line Out For Mixer Board
Post by: plexi50 on July 23, 2010, 09:21:21 pm

Ok i see. I was thinking it looked more like a dummy load than a line out. I got it working with your second diagram. Thanks a mill!