Hi y'all,
I did a little project I had in mind for a looooooooong time and thought this could be of some interest to others..
A SCA rack with 4xN72 and 4xA12 has been with me for about 7-8 years now (and was my first DIY kit project!). Those pres sound awesome and are still my go-to's.
The only drawback was not being able to use the trim as an output fader. When recording close miced drums the gain clicked to 2, max 3 before overloading my A/D convertors.
For a while I searched for a solution but no one seemed to have one - until a few weeks ago I stumbled upon the variable T-pads that CAPI and Hairball sell. A little measuring and thinking later I came up with the following solution:
Needed: 1x variable T-pad (I got the CAPI one - http://capi-gear.com/catalog/index.php?cPath=48 ), 1x 10k resistor and some wire per channel.
- dremel off the back T-pad legs and the part of the PCB that's sticking out its' back
- remove the trim pot from the PCB
- wire in the resistor across the two outer holes and short the middle and "rightmost" (furthest away from the phase switch). Make sure it is flat to the PCB
- unsolder the orange and blue wires from the output trafo (these are the pos and neg outputs of the trafo)
- wire these to the T-pad's IN pos and neg and use two pieces of wire to solder the OUT pos and neg back to the PCB
- assemble the rack again and mount the T-pad upside down.
Works perfectly for me - or did I make some kind of impedance mistake? Anyhow, when testing it sounds like it works :
Enjoy,
Herwig
http://www.prunesandspoons.com/20170101A12DIY/01%20Pre.jpeg
http://www.prunesandspoons.com/20170101A12DIY/02%20trim%20vs%20Tpad.jpeg
http://www.prunesandspoons.com/20170101A12DIY/03%20Tpad%20slimming.jpeg
http://www.prunesandspoons.com/20170101A12DIY/04%20trim%20removed.jpeg
http://www.prunesandspoons.com/20170101A12DIY/05%20resistor%20step1.jpeg
http://www.prunesandspoons.com/20170101A12DIY/06%20resistor%20step2.jpeg
http://www.prunesandspoons.com/20170101A12DIY/07%20resistor%20step3.jpeg
http://www.prunesandspoons.com/20170101A12DIY/08%20resistor%20step4.jpeg
http://www.prunesandspoons.com/20170101A12DIY/09%20wiring%201.jpeg
http://www.prunesandspoons.com/20170101A12DIY/10%20wiring%202.jpeg
http://www.prunesandspoons.com/20170101A12DIY/11%20in%20place.jpeg
http://www.prunesandspoons.com/20170101A12DIY/12%20detail.jpeg
I did a little project I had in mind for a looooooooong time and thought this could be of some interest to others..
A SCA rack with 4xN72 and 4xA12 has been with me for about 7-8 years now (and was my first DIY kit project!). Those pres sound awesome and are still my go-to's.
The only drawback was not being able to use the trim as an output fader. When recording close miced drums the gain clicked to 2, max 3 before overloading my A/D convertors.
For a while I searched for a solution but no one seemed to have one - until a few weeks ago I stumbled upon the variable T-pads that CAPI and Hairball sell. A little measuring and thinking later I came up with the following solution:
Needed: 1x variable T-pad (I got the CAPI one - http://capi-gear.com/catalog/index.php?cPath=48 ), 1x 10k resistor and some wire per channel.
- dremel off the back T-pad legs and the part of the PCB that's sticking out its' back
- remove the trim pot from the PCB
- wire in the resistor across the two outer holes and short the middle and "rightmost" (furthest away from the phase switch). Make sure it is flat to the PCB
- unsolder the orange and blue wires from the output trafo (these are the pos and neg outputs of the trafo)
- wire these to the T-pad's IN pos and neg and use two pieces of wire to solder the OUT pos and neg back to the PCB
- assemble the rack again and mount the T-pad upside down.
Works perfectly for me - or did I make some kind of impedance mistake? Anyhow, when testing it sounds like it works :
Enjoy,
Herwig
http://www.prunesandspoons.com/20170101A12DIY/01%20Pre.jpeg
http://www.prunesandspoons.com/20170101A12DIY/02%20trim%20vs%20Tpad.jpeg
http://www.prunesandspoons.com/20170101A12DIY/03%20Tpad%20slimming.jpeg
http://www.prunesandspoons.com/20170101A12DIY/04%20trim%20removed.jpeg
http://www.prunesandspoons.com/20170101A12DIY/05%20resistor%20step1.jpeg
http://www.prunesandspoons.com/20170101A12DIY/06%20resistor%20step2.jpeg
http://www.prunesandspoons.com/20170101A12DIY/07%20resistor%20step3.jpeg
http://www.prunesandspoons.com/20170101A12DIY/08%20resistor%20step4.jpeg
http://www.prunesandspoons.com/20170101A12DIY/09%20wiring%201.jpeg
http://www.prunesandspoons.com/20170101A12DIY/10%20wiring%202.jpeg
http://www.prunesandspoons.com/20170101A12DIY/11%20in%20place.jpeg
http://www.prunesandspoons.com/20170101A12DIY/12%20detail.jpeg
