I'm a student at SAE Melbourne and have chosen to build a plate reverb unit for an assessment piece.
I plan to build a plate reverb inside a 19" rack shelf (keep in mind this is purely experimental) and I currently have everything I need except the Plate (which is being cut in both steel and aluminium for tests and should arrive in the next week or so) and the Driver.
Here is where my issue lies.
Originally I was under the impression that in order to apply the vibrations to the plate, a speaker had to be mounted in close proximity. This works with a larger plate (to some effect) but as my plate is far smaller and enclosed, a speaker producing very much audible sound is not a suitable option.
Finally I discovered the use of the driver itself.
I have pulled apart a 10" speaker, removed the cone and I am now left with the visible driver.
I'm not entirely sure how to attach the driver to the plate. I've seen examples that use extensions with a bolt on the end which seems like it'll be the best bet.
Does anyone have any suggestions of how to make an extension? Or even better are there any options of buying a driver that is generally used for plate reverb? (keeping in mind I am a student and would rather not spend over $100 on any individual material for the unit).
I'm also curious if there are any ideas to mount the driver as it's not a very big enclosure and I haven't built a plate reverb unit in the past.
Any help or advice on any part of the unit would be appreciated.
For something that small I would use the driver from a pair of headphones. It would also be light enough to mount easily. Get it close to the plate with some screws and use the screws to move it closer/farther from the plate. Great project, please give use some feedback on how it goes!
Headphone drivers? Interesting.
I would've thought they'd be too small to move the plate. Either way i'll cut open a pair tonight and suss it out.
My only concern is that if I don't mount the driver separately would the resistance in pressure from the plate cause the driver itself to move instead; rather than it staying stationary and propelling the plate toward/away from it?
Anyway, i'll get stuck into it and get back to you,
how big and how thin is your plate? without a large plate say at least 3 foot long your going to be sadly disappointed. You also have to come up with a way to have it very taught without flexing if you have that all you need is a speaker on one end and a piezo electric element on the other as your pickup
Excellent little project, do keep us posted.
Was just thinkin. How about a 6" car stereo speaker. Seems would be perfect match and cheap. After all your only after mid's and hi's with a plate that small.
And what would happen if you flipped the speaker over and let the magnet attach it to the steel. Reverse the phase and all that.
The plate size is a concern as I always thought they were more like a 4x8 sheet of material. Anyhow good stuff and have fun.
Actually after having a look at the speaker I have there's no way it's 10". I'm fairly certain it actually IS a 6".
I'm pretty convinced by now after the extensive research that the actual sound of the plate isn't going to be fantastic but this was more of an educational investigation and has already been a massive learning curve. It was more the practicality of the rack mountable unit I was going for, once the project is complete I can make tweaks and adjustments in my own time without deadlines rushing me.
The plates dimensions are 378mm(L) x 140mm(W) depending on what material I use I'm expecting it to be between 3 - 5mm thick.
As far as the phase/magnet idea is concerned, I'll take a look when the plate arrives to see if it works.
Couldn't find anyone who would sell or even ship it to Australia but I did come across a similar transducer by Vidsonix which is a little bigger named "phantom." For some reason Vidsonix (eBay account) will ship the phantom internationally but not the ghost.
I'll have a more thorough look around. Thank you for your help!!
Doulos30 may be talking about the plate not being big enough in which case he's probably right, there had to be a reason they're so big. It's more an experiment though so I'm still going to try and when I'm done I'll post my findings so we can confirm or bust any suggestions that it won't work.
If anyone has any ideas of where I can get a ghost or something of that size sent to AUS it'd be awesome if you could share! I'm still hesitating with the larger phantom
Well would a physically attached driver make a difference do you think? I only ask because of how much research I've had to do on them already that I've found the ones without the driver attached are far less resonant.
no it wouldn't it doesn't matter how big the driver is. think of your driver as a rock you toss in a pool. Your sheet metal is the pool the bigger the pool the more waves will ripple. This ripple is what causes the reverb effect. If you toss a large rock into a small pool you get a big spash i.e a big fast reflection. What you want is a medium size rock that will cause a wave run throught the entire length of the pool ie a constant reflection. The driver was a small 3 inch speaker I suspended on a mic mount, but you can hear what it should sound like by tapping it. If it doesn't resonate it's not large enough or tight enough. Just give up your wasting your time unless you go about 4 or 5 feet long.
With all do respect, This is an investigation. I've said it time and time again. I'm not expecting an emt out of this I'm simply building something that hasn't been done before to find out why. I appreciate your knowledge as it makes complete sense and I had an idea it wouldn't work too well. But I'm not going to stop my project now and fail my unit because I was told to. I don't want you to think I'm not thankful as I asked a question and got a legitimate response, but I'm not going to stop now I'm too far into this.
This would really be more valid on Geekslutz, but we'll do what we can!
First of all - you need to find a driver that's suitable. It has to be high enough power to cause the physical thing to move. A speaker is a viable option but, as I found out with my own trials, the speaker is going to give you an awful lot of direct sound - which is a PITA to deal with.
A DC motor, however, or other mechanicle transducer will allow you to move the spring without moving air. There's a couple of youtube videos demonstrating construction and most stores should sell a DC motor - I would emphasis that this can NOT be a Stepper Motor as they take an input from a PWM source.
Once you know the load from the motor on either side, it's time to design an amplifier around that - though we can expect it to be about 30-100 ohms - a pair of LM4562NA in parallel will comfortably drive the motor - or headphone drivers down to about 50 ohms at around 3-4 volts (from what I've read, you'll need a supply rail of +/- 6Volts, though you can do a split supply design if needs be. If you want to drive it harder, or you have a lower resistance still, you'll have to think about increasing your power rails or setting up another pair of op amps - both can be messy, so breadboard the thing first.
On the output side you've a few options - another motor or speaker, a pickup or a piezo. A transducer will be the most efficent, though the LF content will be very quiet - and a simple High Z buffer and amp should do the trick - a TL072 will give you what you need to comfortably drive a Line In.
As an aside, plenty of Amp Companies sell replacement spring reverbs - so if you're willing to spend about 50 quid on one of those you simply have to find a way to drive it (which I've described above). If time is a factor I'd strongly recommend doing that.