[sdiy] How do reverb tanks work?

[John L Marshall]

A cutting head and a phono cartridge might work better. How much current can 
be run through a phono cartridge before meltdown? Hmm....maybe a 
piezo-cartridge?

Take care,
John
www.sound-photo.com
www.antenna-farm.com

----- Original Message ----- 
From: "JH." <jhaible at debitel.net>
To: "Ray Wilson" <raywilson at comcast.net>; "RMC" 
<RMC at richardcraven.plus.com>; <synth-diy at dropmix.xs4all.nl>
Sent: Friday, November 24, 2006 1:26 PM
Subject: Re: [sdiy] How do reverb tanks work?


>I just learned a few days ago, that the Reverb of Farfisa Compact Organs 
>was
> built
> from two phono cartridges (one as a driver, one as pickup, with a spring 
> in
> between.)
> How cool is that !?!
>
> JH.
>
>
> ----- Original Message ----- 
> From: "Ray Wilson" <raywilson at comcast.net>
> To: "RMC" <RMC at richardcraven.plus.com>; <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, November 24, 2006 7:17 PM
> Subject: Re: [sdiy] How do reverb tanks work?
>
>
> Both sides of the reverb tank are similar they differ mainly in the
> impedance of the coil circuit. The "input" side is generally lower 
> impedance
> and yes your are driving a coil that is causing a fluctuating magnetic 
> field
> to cause the magnetic ferrous bead attached to the reverb spring to wiggle
> causing the spring to wiggle so that on the other end another magnetic
> ferrous bead wiggles and induces a voltage into the "pickup" or output 
> coil
> (generally higher impedance) than the other coil. The signal on the second
> coil is the actual reverb signal which you amplify and mix with your
> original signal to get the classic spring reverb type effect.
>
> The coils are wound with the teeniest wire in the world and fixing them is
> next to impossible. Notice I say... "next to" because with enough 
> patience,
> care, light and magnification I suppose one could reconnect the coil wires
> to the input/output terminals and the thing would be as good as new.
>
> Cheers and Good luck.
>
> Ray
> ----- Original Message ----- 
> From: "RMC" <RMC at richardcraven.plus.com>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, November 24, 2006 10:08 AM
> Subject: [sdiy] How do reverb tanks work?
>
>
>> Hello
>>
>> I'm interested in spring lines and most specifically, the transducers
>> used. Does anyone know the detail of how the output transducer works?
>>
>>
>> The input transducer uses the motor principle to develop torque which
>> imparts torsion to the spring, but how does the output element work?
>>
>> Having just dismantled and repaired a broken springline (the output
>> transducer coil had gone open circuit where the lead-out flex solders to
>> the coil turns, due to 1970s corrosive flux!), I can't understand with
>> certainty how it works.
>>
>> The ends of the spring seem to have tiny ferrite beads mounted on them,
>> which are lined up to occupy an air gap in the output transducer. Either
>> that, or they're magnets.
>>
>> In the former case the gap reluctance presumably gets modulated by
>> movement of the ferrite bead. In the latter case, an MMF gets generated 
>> by
>> the magnetic flux cutting the core (aluminium laminations??) and hence
>> inducing a current in the output coil which is common to the magnetic
>> circuit thus formed.  As far as I can tell, the circuit that receives the
>> tank output doesn't provide a constant current through the coil so there
>> isn't a method of detecting the relucatnce - it must be that the little
>> beads are magnets. Is it true?
>>
>> I managed to leave out a couple of tiny little brittle black (plastic?)
>> "plugs" which appeared to act as some kind of spring damper, where the
>> spring end feeds into a tube, where it gets anchored. This is after it 
>> has
>> passed through the output trasnducer. However, it works without these
>> components (which shattered, hence why they're not re-fitted).
>>
>> There are a load of picrues on my website - which the ISP has just shut
>> down because I exceeded my storage allowance. I'll post a link if I get
>> that problem resolved.
>>
>> Cheers
>>
>> RMC, England
>>
>>
>>
>>
>>
>>
>>
>
>