EMT 140 plate reverb transducer & pickups. I want to build studio quality components.

Hello group.

I am entertaining a spring project for duplicating the famous German made EMT 140 plate reverb units used at recording studios like Abbey Road. The construction of the plate, supports, box, welding and such is really not a problem for me personally. Even the pickups I don't think are a huge problem as there are many out there ready made and it's probably easier to make a high quality pickup than a high quality transducer. I would however like to build my own transducer but don't know exactly where to start. I don't want to go the piezo route that I see out there as I think that is not going to end up being anywhere near usable in a studio. I'm not opposed to converting a hacked up speaker or something that doesn't look pretty as long as it works. The typical plate reverb build (the main structure and plate) I believe is with a steel plate about 1 meter wide by 2 meters long suspended within another steel frame and tuned (tension even on all 4 corners). Also, there is a damper that you need to build to lengthen or shorten the delay. This general construction I don't see to be a roadblock but the transducer seems to be what I think may trip me up. I would just like to get something working before I dive in on several days of picking up heavy metal, welding and fabrication of the supporting structure and plate.

Some things I would like to understand and advice on are:

What type of transducer am I really trying to build here or what type of transducers do you think I should consider? Surface? Tactile? Bone?

Can I use a regular speaker magnet? If so what is too big or too small for the plate?

What gauge varnish coil wire do I use and how many winds for 8 ohm amp?

What sort of material should I wind over?

Should I just modify a speaker or driver?

Are there any other quality units out there ready made to save me the pain of building this transducer from scratch? I do have a Dayton Audio HDN-8 on order to start experimenting but would like to get something better I think.

Building a pickup seems to be infinitely easier since I already know how to build guitar pickups and also there are a huge selection of pickups for things like acoustic and mandolin etc. so that I assume is the easy part of the electronics. Still if there are any design ideas you know that would be studio quality I would like to hear from you. My main focus is the heart of the system and the transducer. I have seen a few different methods converting a speaker by cutting out most of the speaker except for the center and then super glue to a metal rod that would touch the plate or whatever but I'm certain that there may be a more simple solution out there.

Thanks in advance for any replies!


Jack A Lopez3 months ago

There is a Wikipedia article for "Single coil guitar pickup",

And another Wiki article for "Humbucker"

And another for, "Pickup (music technology)"

I am guessing you want to build a pickup coil, and that is why I mentioned the article, "Single coil guitar pickup", first, because that one is probably the easiest to understand.

The Humbucker is essentially two single coil pickups, wired in such a way that stray magnetic interference, like from the mains electricty in the room, is cancelled.

The last article, "Pickup (music technology)" is one that gives kind of a broad overview of all different kinds of methods for sensing the movement, sound, in a vibrating string, and converting that to an electrical signal. I dunno. Maybe you want to read that one first.

I have no idea what the actual electrical characteristics, like output impedance, or signal magnitude in volts, or millivolts RMS, to expect from a typical pickup coil.

However, in the external links from "Single coil guitar pickup", I noticed this link,
and the author of that page has written a number of documents, downloadable from there, in pdf, like,

"How Electric Guitar Pickups Work"

"Guitar Pickups Electronic Characteristics"


and others, and there might be some useful info in those.

iceng3 months ago

Try an analog accelerometer as a sound pick up through an AC amplifier..