Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Effects => Topic started by: tubesornothing on April 11, 2010, 01:15:14 am

Title: No transformer reverb with 12AU7
Post by: tubesornothing on April 11, 2010, 01:15:14 am

I came across a reverb driver circuit which uses 1/2 a 12AU7 and no transformer.  1k/25uF cathode.  It feeds off the plate of the 12AU7 into 0.22uF coupling cap, then into a tank rated at 1.9k input.  The other interesting thing is that the plate resistor on the 12AU7 is only 10k - I presume that is to help with driving the moderately low impedance tank?  Upping the current?

The recovery is a little strange as well.  1/2 12ax7 with a 470k plate resistor. 3.3k/0.1uF cathode.

The reverb works quite well.

Title: Re: No transformer reverb with 12AU7
Post by: sluckey on April 11, 2010, 04:57:26 pm

Sounds similar to some of Magnatone's circuits. Look at page 4 of this pdf...
http://home.comcast.net/~seluckey/magnatone/Magnatone_M10A.pdf

Title: Re: No transformer reverb with 12AU7
Post by: caps8419 on January 28, 2016, 01:38:11 pm

Quote from: sluckey on April 11, 2010, 04:57:26 pm

Sounds similar to some of Magnatone's circuits. Look at page 4 of this pdf...
http://home.comcast.net/~seluckey/magnatone/Magnatone_M10A.pdf (http://home.comcast.net/~seluckey/magnatone/Magnatone_M10A.pdf)

Slucky,

I know this is a very old thread but do you have a new link to this Schematic by chance? looking into a 12DW7 cap coupled reverb as well. Thanks!

Title: Re: No transformer reverb with 12AU7
Post by: sluckey on January 28, 2016, 03:08:24 pm

Click on the world icon below my name.

Title: Re: No transformer reverb with 12AU7
Post by: caps8419 on January 29, 2016, 09:58:51 am

thank you