Outragous Idea....DIY EMT 240

Hi  this probably is an outlandish idea, but I've never seen it discussed before, well online. So before you tell me to put down the pipe, just entertain me for a moment. I want to DIY a plate reverb, but trying to get a hold of the metal is one thing, and then the sheer size of it is another thing. I was entertaining the Idea of a big roll of Aluminum foil I have in the kitchen, and thinking I wonder if I could just use that? Well then come to find out the EMT 240 uses gold foil and the peice of foil it uses is only about 12"s x 12"s!!! talk about saving space. Plus it is capable of RT times of 2 plus seconds! amazing. So I know there are going to be plenty of people that say this project is impossible. I can't help but agree, but also there must be someway to make a decent cheap reverb with some patience and a decent jig to make the Aluminum foil tight enough to shimmer, - I started trying to make a simple jig, but found out pretty quick we'll have to find someway to make the foil tight enough to simmer, its so thin that without tension its like a flabby guitar string... nothing. I'm going to pick up some peizos. one for pickup and one as a speaker. we'll see. any thoughts ideas? just from blowing on a piece of aluminum foil I think it will have a nice shimmering quality to it, tho its just wishful thinking at this point....

oh and some food for thought


http://www.theprescriptions.com/MP3/EMT%20240%20full.pdf

http://www.theprescriptions.com/MP3/EMT%20240%20full.pdf

Some food for thought:

http://www.youtube.com/watch?v=-riR9DyxSf8
http://nicksworldofsynthesizers.com/plate.html
http://homerecording.com/bbs/showthread.php?t=244927
http://electro-music.com/forum/post-243.html
http://www.hometracked.com/2007/01/05/build-your-own-plate-reverb/

Here is a plate reverb a friend of mine recently built:

http://www.ribshackrecorders.com/ribs/node/703

In my view I wouldn't build the frame out of wood, like they have in some of the links.  Wood expands & contracts with the seasons & humidity much more than steel does with temperature.  the studio that I used be in was next to a cabinet maker, & I remember him saying that when he made dining tables he had to put slots in the holes where the screws held the top on to allow for seasonal movement.

Plates sound best when they're in tune, & I suspect the tuning wouldn't be very stable if the frame was made of wood.

Gents, I think the original post is about building a FOIL reverb (EMT240), rather than a PLATE one (EMT140).

I guess the main problem is how to tension an ultra thin aluminum foil without breaking it...?

Axel

I believe it is easier to diy the 140 plate than the 240 gold foil because really serious mechanical skills are needed for the 240. That's probably the reason for noone trying a 240 yet? The gold foil is a real work of mechanical engineering art. Unless someone decides to build and sell the reverb unit as a finished part for a reasonable price I believe it might not make sense to diy a 240. The reverb unit with the motor that moves the damping and so on, that's certainly beyond my mechanical skills.

Michael

If you have ever opened up a 240 you will know that you need serious metalworking tooling & skills to build one.  They really are a masterpiece of engineering. 

The plate assembly is, or is in a sort of square clam shell shaped thing, almost like a baking tray (now there's an idea).  I don't think it's like a conventional 140, where it is flat & tensioned in the corners.

WHo knows, if you want to try it, I would be pleased to see & hear of your results.

not a 240, but an interesting thread.. http://www.groupdiy.com/index.php?topic=10718.20

..I've been contemplating using the concrete wall in my bands rehearsalroom to mount the anchors, instead of building a metal frame, just so that I would have an out of the box reverb when mixing our demos..  ;D ..but that would meen I also need to remove the wall treatment and building a false wall, complete with new sound treatment outside the plate...
j

the structure needs to be very strong and acoustically isolated - for both the 240 and 140 designs...

my EMT140 is VERY sensitive to outside acoustic noise - if you talk near it you can hear it in the monitors (good for spooking out people in the control room  ). i was doing some work on it recently - monitoring the pickups on headphones, and it's freaky... the slightest movements sounds like you're in a cavern/the biggest hall in the world haha.

you'll need to enclose it pretty well or house it in a quiet space - OR NOT... you could leave it open and get DIRECT reverb for drums/amps while tracking... pretty cool. you'll need to roll off lots of bass though, these things are boomy when you drive them with direct sound.

don't forget jim cunningham, he sells parts and has free plans for his echoplates:
http://www.platereverb.com/

Any good pics of 240's insides?

Any good description of how it works?

Any ideas of how/what the foil is - and pickup system?

Jakob E.

unfortunately i don't have any photos of the 240 internals - a studio in town has one, but i don't think they'll let me open it up - it's stacked up near the ceiling of their machine room...

it sounds very nice - quite different to my 140, but unfortunately i'm not familiar enough to put my finger on exactly how they differ. if i get a chance to do a proper comparison i'll try to post it here.

gyraf said:

Any good pics of 240's insides?

Any good description of how it works?

Any ideas of how/what the foil is - and pickup system?

Jakob E.

Click to expand...

http://www.beechpark.com/studioequip_outboard_EMT140.html shows one opened, without the metal can that shields the foil. It is basically a shrunk 140 with a very thin gold foil instead of the steel plate. In the german manual it's called 'portable reverb unit', that's true in a sense because it's small compared to a 140, but still very heavy because there's a lot of damping material inside. I've never opened it so far that I got close to the foil. The manual should give some details? I haven't read the english one posted, the german one is pretty extensive if I remember right. If I remeber right it's driven by speaker coils and picked up by piezos.

Michael

I have had one open, but not too recently.  Like Michael says they are quite heavy, & the mechanism is shock mounted too.

If you look at the interior pic on Michaels link, you can see a white sort of tray with rounded edges.  The plate mechanism is mountedon/in that

Damn wish i'd had seen this thread on friday, had our emt 240 out to take some pics for our new website.
They way a ton almost put my back out moving it with a colleague.  
I took the side off for a peek inside but didn't take any photos. duh!

I didn't open up the clam shell with the gold foil inside. Is it safe to open that up?
Looks like it could be air tight. If it ain't broke and all that...

At some point i need to build a remote for it, does anyone have a Cannon connector for a remote?
Manual can be found here.
http://www.analogrules.com/emt.html
http://analogrules.com/Gallery/EMT

mrclunk said:

I didn't open up the clam shell with the gold foil inside. Is it safe to open that up?
Looks like it could be air tight. If it ain't broke and all that...

Click to expand...

That's why I didn't yet dare to open it, it looks seriously sealed... Our neighbours did open it up because the motor was stuck and said that they successfully fixed it, so it should be possible to do it. Nevertheless, a bit of CJ is is needed for the job 

Michael

Hi All,
One day I was fortunate enough to see the internal gold foil of a faulty EMT240, before it was returned to EMT in Germany, for repair.
I can assure you it is a BEAUTY of electro-mechanical art.
I remember everybody around wanted to mirror them on the gold foil, it was so incredible 
I know we have here clever DIY'ers, but I cannot imagine building a 240.
On the other side building a 140 could be more affordable, but anyway it is not a project for a beginner....
I recently turned back to life a quad (!) EMT140TQ, with new pickups from Jim Cunningham, and I also built a new set of electronics, and it was quite a job....   
Take care, the " unbreakable " clips from JC Associates are breaking a lot when you want to properly tension the plate  :'(
Best,
Guy

Michael Tibes said:

If I remeber right it's driven by speaker coils and picked up by piezos.

Click to expand...

I just browsed the manual mrclunk posted and it's actually the other way around, piezo as a driver and a coil as receiver.


Michael

Need to find out:

- What is the working principle - are there any patents in some patent database?

- What is the foil (no, it's not gold..) - dimensions, material

I have a feeling that the reason this has never been diy'ed is because of lacking knowledge of what is actually going on in there.

Jakob E.

hey guys,

this might be of interest for those who aren't familiar with the sound of the 240 and the 140. i've uploaded a little file onto my website, it has a dry acoustic guitar file, and 100% wet files for the EMT240 and EMT140 (w/ jim cunninham pickups + diy preamps).

the files are 24bit/48k wavs, load them into your DAW, align each one to the same start point and you can blend each with the dry to compare.

both reverbs are extensively EQed both on the send and the return -  to suit the track... i tried to roughly match the sound of the 140, which is at my studio, to the 240 which was recorded a few months ago at another studio. i don't have access to the 240 anymore, otherwise i would have done more comparison files, without eq etc.

an overall comparison of these units is VERY hard - the tuning/eq/decay time settings can make a BIG difference... i bit like saying "this is what a ludwig bass drum sounds like, and now this is what a gretch bass drum sounds like" - there's a lot of variation in the tuning/heads/room etc!

anyway... hope it helps someone. i found, while comparing these particular units, the 240 sounds like it has a combination of closer and more distant reverb (perhaps to do with the placement of the two pickups?) with one side being more distant sounding than the other - while the 140 has more of a even "distant" sound...

the noise floor on my 140 has been improved since the recording - i hadn't calibrated the preamps and they were providing too much gain - so i had to attenuate the send, sorry!

http://www.haima.info/gear/EMT140/EMT140_240_comparison.zip

haima

gyraf said:

Need to find out:

- What is the working principle - are there any patents in some patent database?

- What is the foil (no, it's not gold..) - dimensions, material

I have a feeling that the reason this has never been diy'ed is because of lacking knowledge of what is actually going on in there.

Jakob E.

Click to expand...

The working principle is shown in mrclunks links:

mrclunk said:

http://www.analogrules.com/emt.html
http://analogrules.com/Gallery/EMT

Click to expand...

The foil really is 18 micron gold alloy, 270 x 290 mm. As I said, it is basically a shrunk 140, nothing complicated to comprehend in that aspect. Electronics would be easy to make, the difficulty lies in the mechanical engineering.

Michael