How do reverb tanks work?

[gorch]

Just reading Chromiun's Blues Junior thread, I thought I ever wanted to know how these things magically work. So, please, what's the principle behind the spring tanks? This is a crazy tool. Who did invent the whole thing? Let your knowledge spring.

[Thundersteel]

Along this subject, are there any sonic differences between long and short reverb tanks?

[chromium]

There's a great article w/diags here, if you are interested in the inner workings.  There's also some info comparing sound characteristics of the various tank brands...

https://www.amplifiedparts.com/tech_corner/spring_reverb_tanks_explained_and_compared

 

Might not be fully accurate, but this is how I've come to understand how these things work:

Those multiple springs are intended to simulate the multiple reflective surfaces/walls in room, big hall etc.  The amp's reverb circuit feeds your guitar signal to a transducer on the input side of the springs- which electro-mechanically jiggles 'em, and the vibrations then travel back and forth across the springs... akin to the way sound waves bounce around in a room.  

The recovery/output side of the reverb circuit acts almost like a guitar pickup and preamp for the springs - picking up their movement and mixing that sound back into the amp signal.  Reminds me of those "sympathetic" strings/pickup on a Coral Sitar - similar concept.

The gauge and length of the springs affects how fast the vibrations travel across, and the overall characteristic of the reverb sound.  I'd speculate that longer tanks might be better suited to model a giant hall, and shorter tanks a small venue or room.

[it's me HHB]

Had no good experience w short tanks yuk

[tomteriffic]

Expanding just a little, a shorter two-spring tank will yield a less diffuse (thinner) reverb due to there being fewer springs, and less depth, due to the shorter time it takes a wave to traverse the spring.  That's all else being equal, of course.  Spring tension and circuitry fore and aft of the spring play into it too, to some degree.  I'm not 100% sure of it, but it may have been Hammond that came up with the spring reverb, or at least brought it to commercial success.  Their "spring in a bag", built into their non-Leslie speakers could put your B-3 into any of Europes Medieval cathedrals. A five (or so) foot long spring hanging in a vinyl bag from the top of the cabinet inside.  A wonder.  Fed back like crazy too.

For us mere mortals, for my money, the king-hell spring reverb is the Furman RV-2.  Six springs per side in stereo, 12 in mono, all different lengths and tensions. Input limiters to minimize "boing", EQ on the returns to suit your needs, etc.

 

 

[Bloozguy]

Not as technical as the previous link, but a couple nice pages on the history and theory of spring reverb:

http://www.accutronicsreverb.com/

[Caddie]

40 minutes ago, tomteriffic said:

 

minimize "boing

Maximize SCHWING!

[Bloozguy]

1 hour ago, tomteriffic said:

Expanding just a little, a shorter two-spring tank will yield a less diffuse (thinner) reverb due to there being fewer springs, and less depth, due to the shorter time it takes a wave to traverse the spring.  That's all else being equal, of course.  Spring tension and circuitry fore and aft of the spring play into it too, to some degree.  I'm not 100% sure of it, but it may have been Hammond that came up with the spring reverb, or at least brought it to commercial success.  Their "spring in a bag", built into their non-Leslie speakers could put your B-3 into any of Europes Medieval cathedrals. A five (or so) foot long spring hanging in a vinyl bag from the top of the cabinet inside.  A wonder.  Fed back like crazy too.

For us mere mortals, for my money, the king-hell spring reverb is the Furman RV-2.  Six springs per side in stereo, 12 in mono, all different lengths and tensions. Input limiters to minimize "boing", EQ on the returns to suit your needs, etc.

 

 

Back in my studio days we had an AKG BX 20 spring reverb and an EMT 140 plate reverb. For their size and price the little Furmans were darn near as good as the monster AKG. Of course these days you can buy BX 20 and EMT 140 plug ins that sound killer.

 

[unfun75]

It just does...

 

[tomteriffic]

17 hours ago, Bloozguy said:

Back in my studio days we had an AKG BX 20 spring reverb and an EMT 140 plate reverb. For their size and price the little Furmans were darn near as good as the monster AKG. Of course these days you can buy BX 20 and EMT 140 plug ins that sound killer.

 

Oh yeah.  We had 7 plates, 7 chambers and an AKG.  But you weren't likely to take them on the road.  I guess I was thinking more along those lines, guitar amps and such.  Although during my touring sound days we used that Furman on a number of FOH things.  This was all pretty much before affordable, good sounding digital came along, though.

[Bloozguy]

2 hours ago, tomteriffic said:

But you weren't likely to take them on the road.

You can sure say that again. Even though they start with the same letter of the alphabet, "plate" and "portable" don't belong together

Did you ever get an opportunity to use one of the EMT gold foil plates?

[chromium]

On 7/28/2016 at 11:19 AM, tomteriffic said:

I'm not 100% sure of it, but it may have been Hammond that came up with the spring reverb, or at least brought it to commercial success.  Their "spring in a bag", built into their non-Leslie speakers could put your B-3 into any of Europes Medieval cathedrals. A five (or so) foot long spring hanging in a vinyl bag from the top of the cabinet inside.  A wonder.  Fed back like crazy too.

Hammond did come up with it, as it relates to musical applications.  They refer to that old design as a "necklace reverb" due to the springs being draped off a T-shaped frame.  It was used in some of the early tone cabinets and also in some of the organ enclosures.

My '62 M-101 has one of their early 2-spring tanks, and those are what led to Accutronics (which later became a division under Hammond).

I had a mint Leslie 145 with that thing that I sold to fund my B8S, and I've been meaning to sell the organ once I muster the will power to drag it out of my office.  Just don't play it much anymore.  Sad, but you can't give those old spinets away!  This thread made me look up and realize the tank and its (rebuilt/retubed) reverb amp are worth more than the organ as a whole...