DIY Plate Reverb. Questions, questions, questions.

[A.David.MacKinnon]

Yep. I'm starting to think of this as the beta version. Hopefully I learn all my lessons before I start on the next one.

[Jitters]

I wonder how the plate size effects to frequency response. I assume that a smaller plate would have more high frequency given the same amount of tension, but I think the classic EMT plates are larger than your 2X4 plate though, right? The tension must be extremely high on them.

[A.David.MacKinnon]

An EMT is at least 4x8, possibly bigger (I'm sure someone will chime in). I'm not expecting to compete with the Germans here. I just want something that sounds better than my trashy springs and Alesis Wedge.
I would expect that the biggest difference between my plate and a bigger one will be in the length and character of the decay.

[Jitters]

I gotcha. I was just trying to wrap my head around the lack of high frequency response, since it seems to me that (knowing nothing about it) a small plate should be brighter than a larger one, everything else being equal.

[A.David.MacKinnon]

I'm 99.9% sure the lack of highs is a tension thing

[The Scum]

Think of the plate like a drum - it's got a resonant center frequency (though with a very broad Q). The tension adjusts that center frequency...and in fact, tensioning a plate is a bit like tuning a drum.

With low tension, the center frequency is in the 200 - 400 Hz range, and it sounds a bit like a spring - dark and boingy. Tensioned so the resonance is in the 1-2 KHz range, it sounds much better. A little more high end (though still not much above 5k-ish), and crisper tails.

There was a free Java app for doing acoustical measurements that someone mentioned a while back...I've been meaning to play with it, because a true broadband waterfall plot would be very revealing of these resonances.

[Jitters]

Of course, that makes perfect sense.

[djimbe]

The type of steel that EMT used is also a huge part of WHY their device works the way it does. I've commented on this in other DIY plate threads, because it is an important point. I have a lot of experience with flat carbon steel, because manufacturing it by thousands of tons per day has been my real job for 24 years.

Unfortunately, the stuff that is best for a plate reverb is darn near impossible for those outisde the industry to get their hands on or work with effectively in a home shop. What you really want is material that has been cold reduced but NOT annealed. It's pretty hard and springy...close to brittle even. Hard to cut on a regular shear, hard to weld, real hard to flatten. Boy, does it ring when you hit it though. Very different than what is commonly available.

Which is not to say that a good plate can't be made of what is available. But full hard seems to "transmit" higher frequency vibrations better than annealed material. I'm not a metallurgist, but I'm sure part of the reason is that there are smaller grains and far more dislocations in the full hard crystal matrix than in annealed material. Whatever. The EMT shit rings more than what you can get at your local Big Box, so gathering and reproducing that high frequency data is easier.

I gotta believe that amp and exciter design is at least as good, and probably better, these days than when my EMT 140's were made. Those improvements are what makes a DIY plate possible now. Make that part of your project as clean and hi fidelity as you can to take advantage of the sonics of plate material you can get.

[The Scum]

... is darn near impossible for those outisde the industry to get their hands on...

So you're saying you can hook us up?

How does stainless compare?

[j_howell]

I built a "ghetto plate" five years ago (and then another, smaller one maybe two years ago for my daughter) using the Sonic Ghost. It's okay...I mounted it using the plastic disc it comes with, but after some tweaking, I replaced the long screws that came with it with shorter bolts and used rubber washers, as it had a tendency to rattle a bit (maybe the plastic surface wasn't perfectly flat? I dunno...).

Anyway, having built two this way, I'm thinking for the next one I'd like to try the rolen star, or remove the bolt in the plastic disc of the Ghost's mount to get more direct contact with the plate by using the bolt itself through the plate. And possibly something nicer for a pickup. The homemade contact mics (like those in Nic Collins' article in the last issue of TapeOp) work well, but I'm thinking something like a Barcus-Berry Planar Wave piano pickup might be better. I've also heard that a studio here in KC had a diy plate years ago using higher-end phono cartridges for pickups, which kinda makes sense.

I've found that I use mine mostly as an oddball effect rather than a "nice" reverb, but then again, mine is smallish (maybe 4x3 or so?), made from a piece of random metal I found, and built with a wooden frame, and the whole thing was an experiment. That said, it's a LOT of fun. For guitar, you can just slightly rest the headstock on the frame or directly on the plate for some amazing, controllable feedback. Rhodes sounds spectacular through it as well.

Another thing to keep in mind is what Nic Collins mentions about EQ use in his article. Getting "decent" reverb out of my plate requires a lot of EQ, depending on what I'm feeding it. FWIW, I'm using an Epiphone Valve Jr to power the whole shebang, something a little more "hi-fi" could be an improvement?

Anyway, diy plates are fun! Let us know what you find!

[A.David.MacKinnon]

Just an update on all of this -

I received my Ghost transducer in the mail late last week and just got around to doing a rough install and test today. It's a huge improvement over just blasting the plate with an auratone 1/4" away. Much more high end and much better overall tone.

The next step is working out a pick-up system and building a case for this beast.

[j_howell]

Awesome! Keep us posted. And post some photos!

[E.Bennett]

the pickups from www.platereverb.com really worked out great on our plate.

[tdbajus]

those ghost transducers- could you hook one of those up to a guitar and get crazy feedback?

[Matt C.]

Dave - i like the design of your plate reverb. i have a couple questions for you -

- how deep did the whole assembly end up being with the damper and everything? i'm trying to figure out if i have space for one of these, and i have maybe 12 to 14 inches to work with in my laundry room.

- did the bolted together frame end up being sturdy enough for you to put a decent amount of tension on the plate? or do you think welding it is necessary?

thanks