3' by 6' plate reverb build, use a transformer or DI box on pickups?

[AnalogApples]

I'm building a 3' by 6' plate reverb with 24 guage cold rolled steel. I'm going to use Lightning Boy Audio's suggestion of headphone speakers as the pickups. He plugs his "headphone pickups" into a microphone transformer, then into a preamp. I'm wondering if I can get away with just plugging the headphone speaker cones into a DI box that has built in preamps. I'd like to get the output of the reverb plate to the correct impedance and gain to plug directly into the effect returns of my Tascam m3500.

I'm pretty sure that I don't need transformers if I'm using the DI box with preamps. Can anyone here confirm that I don't need transformers?

A little more about the build: I ordered a Vidsonix Ghost transducer, which they even advertise as being great for making plate reverbs. It's a full range driver and only needs about 10watts. I have an antique Koss tube headphone amp that I'll be using to power the driver. I'll tension the plate inside a steel frame that I'm about to weld up. I think I've spent about $200 on metal for this project. The shop is welding triangular reinforcements onto each corner of the steel plate, for about $50.

Then I'm going to hang a piece of blue foam insulation parralel to the plate. There will be springs pushing the insulation away from the plate, and a wire connected to each of the two mouting brackets for the insulation so I can can pull the insulation towards the plate by taking up more wire. I'm not trying to keep the insulation laser flat, nor am I trying to keep it laser parralel to the plate. I figure if it's roughly paralel and roughly flat, it'll do it's job of shortening reverb times without me having to construct a robust elaborate contraption to hold the insulation. That'll also save a bunch of weight. I'll just have 2 smooth metal rods poking out the top of the frame. Then I'll glue a couple metal tubes to the top edge of the insulation, so the tubes will ride on the metal rods. A light spring on the rod between the frame and the insulation will make the insulation default to a far-away position. I can even run the wire up through the floor to my studio so I can increase/release tension to move the insulation and scare mice away in the basement.

I'm not married so my wife can't stop me.

 

[rob aylestone]

Electrically, the snag is just loading. The speaker impedance is almost short circuit to whatever comes after, so connected to a 200-600 ohm typical input means very low input level. Think of it like a ribbon mic. You have a specially designed transformer to produce 200 ohms-ish for a mic input. A line input on your mixer wants a higher impedance. I dont think the DI preamp will be that useful? Small speakers also have compromised frequency response used as mics, as the surrounds are very stiff, so they also sound very dull. When i was a teen in the 70s i connected everything to everything with at that time, little science. I connected speakers to guitar amps, and got words out. Sounded very bassy and dark. Inside a kick drum the volume and tone worked, voice was grim. Just a thought? How about a guitar pickup? Placed near the plate, i wonder if that would produce audio? The other thing is that speakers as energisers are pretty inefficient. Lots of noise to get a little mechanical input to the plate.

I suspect once you get the plate mounted, you will have lots of fun energising it with various devices and capturing it again the other end. We cant really advise, as so much depends on being with you!