DIY Plate Reverb

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pitol678

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Hi folks,

I built a plate reverb about 4 years ago and about a month after I finished it, our twins were born, and needless to say it was put on the back burner. Recently Ive had more time to get back into writing/recording and want to use it for a new EP thats close to the mixing stage. So, Im just curious if anyone else may have experience with plate reverbs and am interested in how you use them. For instance, do you send tracks in groups or one at a time? Any specific way you EQ or use effects for returns and sends? Stereo and/or Mono?

I attached a pic, lots of messy wires and I still need to build a damper, and Ive also attached a link to a sample I did when it was first built. I'd love to see photos of other plates, DIY or otherwise.

Sax Through the Plate Reverb I built (100% wet) | The Mighty Lonelys

IMG-3805.webp
 
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Is the plate steel? If it was non-ferrous you could investigate electro-magnetic damping, even NFB now that you can get seriously powerful amplifiers pretty cheaply.

Dave.
 
Thanks!

Dave, Its 24 or 26 gauge cold-rolled steel. I used the plans from jcc and associates and I think they recommended 26 gauge steel. Im wondering if acoustic ceiling tile may work as damper material? Are the amps you mentioned for driving the plate? Would love any recommendations as I'd like to experiment with something other than my headphone amp. Ive got a piezo preamp for the return signal thats supposed to be here today so I'll see how that works
 
pitol678 said:
Thanks!

Dave, Its 24 or 26 gauge cold-rolled steel. I used the plans from jcc and associates and I think they recommended 26 gauge steel. Im wondering if acoustic ceiling tile may work as damper material? Are the amps you mentioned for driving the plate? Would love any recommendations as I'd like to experiment with something other than my headphone amp. Ive got a piezo preamp for the return signal thats supposed to be here today so I'll see how that works
Click to expand...

Woah! I don't know jack about reverb plates! I did not know it was a recognised "kit". I was just thinking "variable eddy current damping" but I doubt that would work with a magnetic plate. The amps would be for driving the damping coils.

But, I would guess you would need something a bit more pokey than a headphone amp? The spring reverbs used about a 1-2 watt valve drive and the stand alone jobs a 6V6 pushing 3-5 watts. You can buy quite cheap self contained amp modules that will run from a 12-18V wall rat supply and deliver up to 10 watts. Does the transducer have an impedance and power input spec?

Piezo pickups generally want to "see" 5 to 10 meg Ohms and IIRC plates had multiple pups that could be mixed to give different "arrival times" as in a real room. You can build the amps using jfet op amps, the TL072 or better.

QUITE a project you have there!

Dave.
 
ecc83 said:
Woah! I don't know jack about reverb plates! I did not know it was a recognised "kit". I was just thinking "variable eddy current damping" but I doubt that would work with a magnetic plate. The amps would be for driving the damping coils.

But, I would guess you would need something a bit more pokey than a headphone amp? The spring reverbs used about a 1-2 watt valve drive and the stand alone jobs a 6V6 pushing 3-5 watts. You can buy quite cheap self contained amp modules that will run from a 12-18V wall rat supply and deliver up to 10 watts. Does the transducer have an impedance and power input spec?

Piezo pickups generally want to "see" 5 to 10 meg Ohms and IIRC plates had multiple pups that could be mixed to give different "arrival times" as in a real room. You can build the amps using jfet op amps, the TL072 or better.

QUITE a project you have there!

Dave.
Click to expand...


I dont know much about it either :) Its fun to toy with though and Ive learned a lot through the process. What you said about the headphone amp makes sense, I went back and read through the plans and a 20w amp was suggested. They even give you a diagram on how to construct it, but thats way over my head at the moment. Come to think of it, the time I got the best results was when I used my stereo receiver to amplify it!

I plan to do some tests this evening and Ive already connected the piezo preamp, just got to wait for the kiddos to go to bed. If anyone is interested Id be glad to post the plans or send them. I looked for them online and cant find them anymore.
 
Cebek 15W Mono Amplifier

Something like the above should serve and they do a 35W ready built version. Just need a small screwdriver and a case to bolt the chip to as a heat sink and a 1 amp 24V wall rat. But, as you found, the hi fi receiver worked well and a trawl round charity shops and Cash Generator places could find you something useful.

Something to investigate is "current drive" . Audio power amps have a vanishingly small output resistance, well under 1 Ohm and this gives "voltage drive", a mode speakers are designed for. However, the drive coil of a reverb unit is very inductive and better results, flatter response might be gained from inserting a resistor, 10 to 100 Ohms in the drive circuit. It can do no harm.

Dave.
 
BTW, in investigating the "EMT Plate" I discovered that the post war recording industry was (prob' mainly USA) virtually working for the Juke Box market?

The JB people found the old style recordings, one or two mics, fairly distant BUT in a nice room did not really work for their "pop" scene and so recordings were done in virtually dead surroundings.

This practice did not however go down well with classicist and the emerging hi-fi crowd and so the Reverb Chamber was born. Since not every studio had a spare, cavernous space in which to setup speaker and mics the Plate was developed.

Any just post WWll "big studio" peeps about to confirm or deny?

Dave.
 
ecc83 said:
Cebek 15W Mono Amplifier

Something like the above should serve and they do a 35W ready built version. Just need a small screwdriver and a case to bolt the chip to as a heat sink and a 1 amp 24V wall rat. But, as you found, the hi fi receiver worked well and a trawl round charity shops and Cash Generator places could find you something useful.

Something to investigate is "current drive" . Audio power amps have a vanishingly small output resistance, well under 1 Ohm and this gives "voltage drive", a mode speakers are designed for. However, the drive coil of a reverb unit is very inductive and better results, flatter response might be gained from inserting a resistor, 10 to 100 Ohms in the drive circuit. It can do no harm.

Dave.
Click to expand...

Thats very helpful, thanks a bunch! I'll investigate current drive and voltage drive, I have very limited knowledge of circuitry and electronics and would like to educate myself further

ecc83 said:
BTW, in investigating the "EMT Plate" I discovered that the post war recording industry was (prob' mainly USA) virtually working for the Juke Box market?

The JB people found the old style recordings, one or two mics, fairly distant BUT in a nice room did not really work for their "pop" scene and so recordings were done in virtually dead surroundings.

This practice did not however go down well with classicist and the emerging hi-fi crowd and so the Reverb Chamber was born. Since not every studio had a spare, cavernous space in which to setup speaker and mics the Plate was developed.

Any just post WWll "big studio" peeps about to confirm or deny?

Dave.
Click to expand...

Very interesting!
 
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Before the internet, I had seen pics of Plate Reverb units. Never got to see the real one, though I got to see the "room" it was kept in and we got to use it.

As i recall, it wasn't super duper for an overall mix but was great for some individual parts.

Seems to me the transducers (speaker and pickup) were mounted in opposite corners. Attached directly to the plate, not on stand-offs away from the plate.

Further, they were 4X8 plates as they found anything smaller than 6 feet produced very unnatural cancellations... or something. It's a bit foggy. It also occurs that these were darned heavy plates: like 3/8inch or maybe 1/4.

Of course, it depends on the sound you want. Anyway, that's about what i can remember of my experience.
 
Gtoboy said:
The spring reverb tank in my old G60t amp is driven by what is basically an auto stereo amp chip. You can get something that will probably work from someplace like Parts Express: Speakers, Amplifiers, Audio Parts and Solutions
Click to expand...

Indeed. YEEOnks ago I build son a small battery amp for busking in Paris (as y'do). Stereo car graphic EQ and booster. Put out about 5W per so I used a Tl072 to drive each side out of phase and turned it into a bridge mode amp. Had a gash 6" speaker about and that was pretty loud powered from a 12 V Sealed Lead Acid.

Lasted about a month and then it and a bloody red guitar got nicked!

Dave.
 
I’ve built a similar plate reverb, a bit smaller, probably about 3’ by 4’. I just use a little Radio Shack amp to drive it in the middle, and a piezo on each end goes straight into my interface. I just put an eq on my master bus and set up a mix that I think will play well on the plate, usually cutting any boominess and boosting mid highs. Once I’ve sent that mix to the plate and recorded it to a new track (which was muted while being recorded) I disable the eq and mix the plate sound into my mix. My whole plate rig was made out of junk I had on hand and was really just an experiment, but it works so well and is so fun to play with that it’s become a permanent fixture
 
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