My DIY Plate is done and works like a charm :)

[Harvey Birdman]

Hi Robin, this has to be one of the best DIY projects I've seen. You've managed to research, reverse engineer and and construct a classic piece of recording history and at the same time document the whole process to make it easy for other DIY'ers to take on a build of this size.

In a time where it so easy to reach for a digital reproduction of the original it's good to see someone like yourself putting in the effort to recreate the analog original. I'd imagine it was a very rewarding experience for you.

Looking forward to seeing what your next project is. Thanks for sharing.

 

[saint gillis]

My plate project is in standby since 5/6 years, I had many other things to do and I was a bit blocked by the damper construction.
I'm going to finish it, I'll use some flat 15 or 20mm acoustic foam. This panel has to be very flat and I'd like it not to be too heavy, so I'm going to do a kind of aluminium structure with angle and square bars.

I'm going to use humbuckers to receive the sound. Maybe I'll add piezos later.

I remember when I was testing piezos a long time ago that the sound was very good, full of beautiful bass, when I was gently pressing the piezo with my finger. Then I've read somewhere that some plates used a system with a small element on a spring applying a little pressure on each piezo, I don't recall if the EMT used that or another manufacturer, but this could be useful information for diyers.

 

[abbey road d enfer]

I remember when I was testing piezos a long time ago that the sound was very good, full of beautiful bass, when I was gently pressing the piezo with my finger.

It's a known fact that applying pressure on piezo transducers notably increase level AND bass.
But adding mass has just about the same effect, and doesnot result in additional damping.

Then I've read somewhere that some plates used a system with a small element on a spring applying a little pressure on each piezo,

I may want to try that, but I bet it would reduce the reverb time significantly, which may not be desirable.

I don't recall if the EMT used that or another manufacturer, but this could be useful information for diyers.

The brass cylinder which houses the piezo pick-up is the additional mass.

 

[thomasdf]

I have always wanted to build one of these, and been lurking on this thread since OP started it .. i am just waiting for a near future when/where I have more room

Re the transducers, I will give a shot to a pair of mono phono cartridges, just for the sake of it ... because I have heard "noise" artists performing with phono cartridges on various metal parts and the sound was interesting.

 

[abbey road d enfer]

Phono cartridges need to be attached to some mass to operate properly.

 

[rock soderstrom]

Member seems to be inactive since July 20222...

No wonder, he now seems to be living with you in the distant future! 20222! How is it there?

 

[thomasdf]

Phono cartridges need to be attached to some mass to operate properly.

I was thinking the chassis ! With some arm & set screws allowing for precise clearance set, etc. The idea is the only moving part is the stylus, in theory
Well, only ideas at this point ... ! Maybe one day !
The harder part of the build seem to be finding the main sheet in correct material and thickness !

 

[abbey road d enfer]

The harder part of the build seem to be finding the main sheet in correct material and thickness !

Cold roll steel is commonly available in France in 2x1m size, except thickness is 0.6mm.
Not a deal breaker IMO.

 

[abbey road d enfer]

No wonder, he now seems to be living with you in the distant future! 20222! How is it there?

Well, the good news is Elon Musk, against his predictions, is long dead.
Bad news is I have athritis.

 

[saint gillis]

It's a known fact that applying pressure on piezo transducers notably increase level AND bass.
But adding mass has just about the same effect, and doesnot result in additional damping.

I may want to try that, but I bet it would reduce the reverb time significantly, which may not be desirable.

The brass cylinder which houses the piezo pick-up is the additional mass.

How do you add mass to a piezo? On top of it ?

 

[Evertide]

Great job! congrats

Which material did you use for the damper? (the panel on which you fixed the acoustic foam)

From the pictures it looked like 3mm plywood...

 

[abbey road d enfer]

How do you add mass to a piezo? On top of it ?

You must add mass to the body. It depends on the construction but yes, often on the top, where the wire is.

 

[saint gillis]

from this document : https://www.bbceng.info/ti/eqpt/EMT140.pdf

" The piezo-electric microphone is mounted in a cylindrical steel case which has a cone-shaped point spot-welded or screwed to the reverberation plate. The microphone consists of a barium-titanate plate, 1 mm thick and 12 mm in diameter, cemented to the case and in contact with a mechanical mass which makes it sensitive to acceleration. A disk-shaped compression spring safeguards the cemented connection between the mass and the case.
The microphone is free to move inside a screening can mounted on a vertical cross-member of the plate frame, and a removable cover to the can gives access to the microphone and its flexible connections. These connections terminate on soldering tags to which the screened coaxial cable leading to the amplifier is connected. "

 

[13engrsapper]

I have been hoarding various sheet stock and other fun metal things for just such a project, way to go man. Once things settle here, building a reverb of some sort is a priority for me... just a boredom chaser project.

 

[Tubetec]

Nice simple drive amplifier , puts out about 1w , same circuit would also drive an 8 ohm spring very adequately , I use a wirewound pot to attenuate the drive ,allowing the amp to be driven harder without the drive transducer saturating or subsequent overload of the recovery circuits .