How to change the decay time of a spring reverb tank?

[Matador]

I can only repeat myself, thank you very much for the numerous ideas and information! There is a lot of exciting stuff in here.

My experiments so far have shown that electronic control (signal processing) of the decay is effective but also changes the original sound. I see that as an useful add-on.

As a basis, I will rather favour corresponding tanks with different decay lengths, possibly also mechanically modified.

The topic of the position of the springs is also interesting and deserves its own thread.

My current test setup switches the individual tanks, which works well, but my next design will make the individual tanks variable mixable. That brings a lot of advantages.

Not sure if it helps: I know a guy with a deluxe reverb that has brought it in to me to repair twice now with destroyed reverb tank springs. He travels with the amp often and isn't 'kind' with it, to the point where the springs are bashed into the floating aluminum frame repeatedly until the magnets pull from the transducers and then he calls me.

In the last MOD tank I used, they fit two foam pads to protect the springs during shipping: one "underneath" (between the spring and the floating channel), and another above to clamp the springs into place. I found if you remove only the top pad, the bottom pad is fit so it just brushes the springs from underneath but doesn't really prevent them from vibrating much.

We found he is much happier with the bottom foam left in place, because it allows him to use above 3 on the reverb control, and the decay time is reduced and the reverb is more lush and not so "over-washed" in echos. Plus, if the amp takes a blow, the springs hit the foam pad and cannot contact the bottom aluminum channel any longer.

I know this doesn't directly address your question (I think you want to be able to control this from a front panel), but it's something I hadn't considered before and it ended up being an elegant solution.

 

[Zed80]

To reduce the length of the decay, what about one or several magnets put near the strings (at the middle of the can may be) ? It would be possible to mount them perpendicularly on a board and reduce or increase its proximity to make vary the dampening effect. But would it work actually ?

 

[gyraf]

Would not dampen, as no energy would be removed like this, I think..

 

[rock soderstrom]

To reduce the length of the decay, what about one or several magnets put near the strings (at the middle of the can may be) ? It would be possible to mount them perpendicularly on a board and reduce or increase its proximity to make vary the dampening effect. But would it work actually ?

I've had similar thoughts, but I don't know if it works...

 

[Perm0]

The pic shows my damping system, two veltpads on bolts offset at a simple rotary axis, so a slight turn dampens one outer spring and turning it more dampens both outer springs.

File starts off dry, think it was then dampened and opened towards the end.
You can hear a screatchy noise going on while I turn the veltpads.

 

[musipol]

I could be way off here, but wouldn't the damping have been more obvious using a more decaying signal? Maybe a guitar string pluck or a piano?

 

[Quantum J Audio]

Just posted in this forum about redesigning a Hot Springs. This is the post. Take a look at page nine of the build manual I uploaded. They suggest using a rubber band to modify the reverb size.

 

[metalockpick]

Hi guys, I'm currently working hard on spring reverbs and was wondering how to change the length of the reverb tail of a spring reverb?

My original plan was to buy three corresponding versions, but the short decay 1 types are very difficult to get. In addition, with a stereo device it becomes then six pans. The gradations are also quite coarse and they also sound very different.

My ideal idea would be a two long decay types for left and right that one could damp steplessly (mechanically or with oil??) and thus adapt the decay times to the sound material.

Does anyone have ideas and experience?

I found the following video.


Cheers

Since I was a kid, I always cut and shortened the springs... Two things I've learned since then is that short/medium decay is more to my liking, and that decent sounding pans that have been played for years (not necessarily old pans, some of them are horrible) sound far better than new ones.

 

[k brown]

I always thought the decay time of a spring reverb was determined entirely by the physical length of the spring(s) - no?

 

[zamproject]

I always thought the decay time of a spring reverb was determined entirely by the physical length of the spring

Not being expert in sound travel in complex material I suppose the length of the spring primarily define the pre delay, which is fast in metal (few km per sec...), so probably irrelevant for usual spring reverb ?
Now there is multiple oscillations modes involved, longitudinal, transversal, bouncing waves as the ends are static etc...
So the decay is somehow dependant of the length, but correlated with frequency, energy, natural damping, absorption and resonances also defined by the spring length and tension.
I -visualize - it like a string, but with more complex and chaotic behaviour.

It's easy to feel (and hear) transversal modes in a spring reverb by touching it at sequential distance like in a guitar string, killing fundamental resonance by touching the middle, fifth at 1/3 etc...

This topic showing up again remind me I have to fix my BX20, I miss it.

 

[Quantum J Audio]

Reverb, into echo, part fed back into the reverb.

Doing this kinda of stuff is always great for creating space and depth. Also common to put pre-delay into springs and plates.

Waves CLA epic dedicated plugin to this kind of effect routing.

 

[Tubetec]

I fitted a spring with an adjustable damper
it can be moved to make contact with either or both springs ,
Damps a lot of the shrill high end , but also help prevent larger excursions of the spring , so tightens up a low end as well ,
A gate can be used to very effectively reduce the decay time of a spring , decay can be made longer by the use of regeneration ,or feeding back some of the reverb output back to the input , this also effects the density of the reverb ,

 

[Scott Harmonic]

guitar-amps- i use a small piece of very soft foam, set to just touch the springs in the middle of their length.. that prevents the metallic ringing sound and you hear mostly just one long pronounced repeat. - sounds more like echo, and without the metallic jangling, you can dial -in a LOT more of the effect before it sounds stupid.... on some late model guitar amps the tanks have a piece of yellow foam above the springs. ( to reduce bouncing when carrying around) those tanks are easy- I just turn them up-side down, -so the springs will touch the foam in the middle/where they sag. though I'm liking the idea of an external adjustment like the fellow above

 

[Tubetec]

Ive lined the floating alluminium sub assembly with felt ,
It prevents the springs hitting metal if the amp is jarred , but also helps tame the high end a bit .

The other thing is ,
Theres a hole in the sub assembly ,it prevents sideways movement of the tray beyond a certain limit ,
I put a rubber grommet in the hole , again it just prevents another metal on metal contact point if the unit is jarred , which normally results in that horrific metalic clang . After the mod if the unit is subject to vibration or impacts its a much duller clunk sound that results .

The other thing to watch out for is orientation of the tank ,
Tanks are specified to opperate either horizontal or vertical ,
its to do with the offset because of the weight of the springs hanging ,
When a tank is orientated correctly the magnetic slugs hang directly in the magnetic gap of the transducers , if its wrong the slugs are off centre and may even come in contact with the core ,
If the slugs are missaligned you also loose signal level , so always mount your tank in the plane its designed for ,

 

[metalockpick]

I always thought the decay time of a spring reverb was determined entirely by the physical length of the spring(s) - no?

Kinda...Delay time is somewhat analogous to the length of the wire in the wound spring. Cutting the spring and then pulling it out reduces the mass / increases the resonant frequency of the spring, while lowering the Q.

What I've done to help increase the life of springs in touring gear is to laminate business cards with silicone adhesive, and use them as bumpers for the pan, underneath and on the ends and sides. You want to limit the amount the tank can move before the center assembly slams into the frame. The laminated cards will also dampen the blow, reducing damage.

 

[L´Andratté]

Ok, not totally in on the loop here, but has using an trigger extractor plus envelope generator and vca been ruled out already?
I have done that (using a low pass gate, to combine level and freq. response) and it worked out nice, in a synth context though.

 

[gyraf]

I'd like to dip one end of the spring in oil, use pumped oil level to control reverb time.. (?)

/Jakob E.

 

[pvision]

Hi guys, I'm currently working hard on spring reverbs and was wondering how to change the length of the reverb tail of a spring reverb?

First thing I thought of was to mount the whole assembly above a bath of oil with a lever to lower it into the oil

Yes, a crazy idea. But I bet someone has tried something similar...

EDIT: I posted while reading page one. Just saw my post and Jakob's post directly above suggesting the same thing

Either brilliant minds think alike, or Jakob & I share the same madness!

 

[gyraf]

What about this magnetically-controllable oil (ferro-fluid) ?

 

[Perm0]

I could be way off here, but wouldn't the damping have been more obvious using a more decaying signal? Maybe a guitar string pluck or a piano?

Yes it would, but that clip is many years old, it was my first spring experiment with the intention to use it on synth.
I was driving it from a power amp ripped from a small PC speaker the tank had a 10 Ohm input, that tank went to a friend of mine as I now have a dedicated driver + recovery amp circuit feeding a stereo set of medium tanks from an aux bus of my mixer.

I did not add the dampers to my stereo system, I intended to add more tanks in a paralel fase flipped contraption, 4 tanks per channel, 8 total to eliminate the percussive "poing" response to make it more suitable for drums and percussion.

Did not do that yet.... might still do it at some point.