Driving a Plate Reverb

[morls]

Hi,
Looking into building a plate reverb, wondering if there are purpose-built amps available? If not, looking at DIY options.

Seen an example using this:
BSS TCS-804
What I like is the time delay controls, which seem ideal for reverb.

The transducer under consideration is this:
Vidsonix Ghost

What's needed is a HPF, but very steep. An EQ solution isn't steep enough. I've come across the Butterworth Filter, would this be a suitable design?
Butterworth Filter

3rd order is -60dB/Octave, 4th order is -80dB/Octave.

Cheers
Stephen

 

[Brian Roth]

That's dB/Decade. 3 pole is 18 dB/Octave, 4 pole 24 dB/Octave.

Bri

 

[morls]

Thanks Bri,
I took Decade to mean doubling of frequency .

 

[abbey road d enfer]

Hi,
Looking into building a plate reverb, wondering if there are purpose-built amps available? If not, looking at DIY options.

Seen an example using this:
BSS TCS-804
What I like is the time delay controls, which seem ideal for reverb.

The delay line is something you connect in cascade with te reverb, generally before, but can also be after.
It has nothing to do with driving the plate.

The transducer under consideration is this:
Vidsonix Ghost

I second this type of transducer.

What's needed is a HPF, but very steep.

Says who?

An EQ solution isn't steep enough.

Huh?
Indeed a HPF is needed, but it does not need to be particularly steep. It is just there to make sure the driver does not receive excessive power at LF, because this excess power would be wasted in heat.

I've come across the Butterworth Filter, would this be a suitable design?
Butterworth Filter

B'worth is just one member of a family of filters. Operationally, there are many other filters that could satisfy the basic need. I would challenge anyone to distinguish between a B'worth, Chebychev, Bessel, Legendre... of identical frequency and order.

For the driver, a very basic amp of about 10W is all you need. You don't need to have very low distortion (the driver's distortion is several orders of magnitude higher that that of the amp), nor extended freuency response (plate reverb typically goes from about 100Hz to 8kHz).
You'll need EQ on both send and returns, though.

What do you intend to use for pick-up? Piezo p.u's are not bad, but I prefer magnetic guitar p/u's, although they require a good adjustable mounting system.

 

[JohnRoberts]

B'worth is just one member of a family of filters. Operationally, there are many other filters that could satisfy the basic need. I would challenge anyone to distinguish between a B'worth, Chebychev, Bessel, Legendre... of identical frequency and order.

Not much difference well below the skirt, but significant differences in the transition region.

Probably not very audible for that application.

JR

 

[morls]

For the driver, a very basic amp of about 10W is all you need. You don't need to have very low distortion (the driver's distortion is several orders of magnitude higher that that of the amp), nor extended freuency response (plate reverb typically goes from about 100Hz to 8kHz).
You'll need EQ on both send and returns, though.

What do you intend to use for pick-up? Piezo p.u's are not bad, but I prefer magnetic guitar p/u's, although they require a good adjustable mounting system.

Thanks for this information abbey. From my experience with guitars I assume humbuckers would be the way to go?

The comments re: filter curve are something a colleague with decades more experience than me has made. I like the idea of switchable high-pass with 3 or 4 settings

 

[abbey road d enfer]

Thanks for this information abbey. From my experience with guitars I assume humbuckers would be the way to go?

Not strictly necessary but yes it sure would take care of hum. BTW guitar p/u's are relatively high impedance, so you can't run them through long cables. The use of a buffer is recommended. For trial, you can use an active DI.

The comments re: filter curve are something a colleague with decades more experience than me has made.

As I said earlier, the difference in terms of perceived quality is minimal.

I like the idea of switchable high-pass with 3 or 4 settings

You could use a variable HPF. IMO it's the most versatile option. You may use whatever you have in your DAW to evaluate the needs for a hardware version, or use a kit such as this one Pro-Filter kit, 38,50

 

[Gavin Pursinger]

I used a JBL 2561 1" horn driver and a small 8" hifi woofer with an old Altec 500hz passive xover this was mounted about 1-2" from the center of the plate. 10 band passive eq on the send and small tube amp to drive it. Hang time was controlled by how hard you hit the plate. Pick up was contact mic(s) fed thru a 12at7 preamp capacitor coupled...WORKED VERY WELL FOR ME...HAVE FUN....

 

[abbey road d enfer]

How did you couple the speakers to the plate?

 

[Gavin Pursinger]

I did not directly touch the drivers to the plate. Instead I built a housing for them that kept them a couple inches from the plate surface. Sorry, I meant a JBL 2461HORN DRIVER. This is an affordable alnico driver w/a phenolic diaphragm. Probably any decent smooth sounding driver would work. The lower xover point (500hz) is helpful here but it does not take much woofer to buckle the plate so equalizer before the drive amp is necessary and moving it off center might be helpful. I passed on a pinpoint drive as I thought this 2 way drive would work AND IT DID!!!
HAVE FUN.

 

[abbey road d enfer]

I did not directly touch the drivers to the plate. Instead I built a housing for them that kept them a couple inches from the plate surface. Sorry, I meant a JBL 2461HORN DRIVER. This is an affordable alnico driver w/a phenolic diaphragm.

Affordable? Who are you? Elon Musk? Jeff Bezos? When you can find them, they are usually about $200 apiece, and often you need a replacement diaphragm.
The current model is the 24461, $900!

 

[Gavin Pursinger]

The drivers did not touch the plate surface and were placed on frame that kept them a couple inches away from the plate surface. Sorry , I meant a JBL 2461 which is an affordable alnico driver with a phenolic diaphragm...probably any smooth horn driver would work. The low xover (500hz) was helpful here as it does not take much woofer to buckle the plate...so an equalizer before the drive amp was required.. I felt a pinpoint contact driver would be a risky venture and this method might work AND IT DID...ENJOY YOUR PROJECT

 

[Gavin Pursinger]

Jbl 2461...not whatever you said...I am not a rich cat...that is why my stuff is DYI

 

[Gavin Pursinger]

SORRY FOR THE DOUBLE POST
I AM NEW TO YOUR SITE AND STILL LEARNING

 

[Gavin Pursinger]

Try eminence 2002 at $75. Or any old EV horn driver off crsigslist...Plate is not going to 20 kHz. AN old rugged used Atlas pd60 probably would not even need a woofer ???. Decent driver off Craigslist could be found... buy a beat up old monitor cab and gut it...driver xover jack plated and all...just trying to help...
.

 

[Gavin Pursinger]

NO HORN...JUST DRIVER

 

[musipol]

I have wondered if air coupled drive from a speaker would work to drive a plate........................and I see from these posts that it will.

@Gavin Pursinger , If I might ask, do you get a decent S/N when you mix the plate back in?

 

[dmp]

I've used a small active monitor speaker to drive a plate for years - and the studio I got it from did the same thing! It compares really well to the ecoplate attached driver. Very same sound except the low frequencies, which you don't want anyway.
If you look up the schematics from Jim Cunningham, the driver has a HPF. The return amps also have EQs, but I've found I don't need those.
Put the plate in the drum room and the live drums will drive it!
You'd do well to use a plate for awhile before building any electronics to decide what you need.

 

[morls]

Awesome info here, thanks everyone