Reactive Load/Line Out

[Arch Stanton]

Anyone tried building one of these ?

It's a pretty good project for getting your feet wet with electro-assembly & soldering. Much simpler than building an amp.

I built this one based on Randall Aiken's posts over on TGP :

schematic:

 

[mnemonic]

I made one also based on the legwork done by a bunch of guys in that long thread on tgp, which was based on the stuff Randall Aiken has on his site.

Works fantastic. I tweaked the values to be as close as possible to the measured impedence curve of my cab and I think I nailed it - my recto in modern mode (notoriously touchy when it comes to the load used) sounds the same loaded and reamped with a SS poweramp, or direct into the cab.

Inductor proximity to the aluminum housing gave me a real headache at first, too close to aluminum and the reactive element is significantly reduced. Apparently the opposite is true if using a steel enclosure (assume the inductors start to act like iron core inductors)

 

[Arch Stanton]

I made one also based on the legwork done by a bunch of guys in that long thread on tgp, which was based on the stuff Randall Aiken has on his site.

Works fantastic. I tweaked the values to be as close as possible to the measured impedence curve of my cab and I think I nailed it - my recto in modern mode (notoriously touchy when it comes to the load used) sounds the same loaded and reamped with a SS poweramp, or direct into the cab.

Inductor proximity to the aluminum housing gave me a real headache at first, too close to aluminum and the reactive element is significantly reduced. Apparently the opposite is true if using a steel enclosure (assume the inductors start to act like iron core inductors)

Looks like you used the Erse Audio Super Q coil as well.

 

[mnemonic]

Looks like you used the Erse Audio Super Q coil as well.

Yes, I used erse for both inductors and the big film caps. Lots of good options but when I was searching for parts it seemed like the best option. One of the more expensive sources but still all-in was about half the price of the suhr reactive load here in the U.K. Also I like making my own stuff when I can.

 

[Arch Stanton]

Yes, I used erse for both inductors and the big film caps. Lots of good options but when I was searching for parts it seemed like the best option. One of the more expensive sources but still all-in was about half the price of the suhr reactive load here in the U.K. Also I like making my own stuff when I can.

How did you plot your impedance curve ?

I had to feed in an audio signal at various frequencies and measure VAC in order to plot the curve on a graph.

 

[mnemonic]

How did you plot your impedance curve ?

I had to feed in an audio signal at various frequencies and measure VAC in order to plot the curve on a graph.

I used room eq wizard, and soldered together a couple wires and 1/8” phone plugs to plug into my computer sound card as shown here -
https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html