Hammond reverb lightbulb limiter /twin pot attenuator

Below are two of the lightbulb limiters used by Hammond , fed from the console amp which was usually 4xEL84 into 8ohms .
I see one has single bulb the other dual .

Ive used a simple 200 ohm wirewound pot before as input attenuator for a spring , runs ok off anything from solid state op amps to big guitar amp speaker outs .

I found some dual wirewound pots and was wondering if it would be  possible to combine the lightbulb lim and a variable attenuator using the two pots . With the lightbulb limiter followed by the simple 200 ohm  attenuator  as soon as any attenuation was dialed in their wasnt enough current to light the bulb anymore .Could I simply replace the two resistive elements in the hammond drawing with two pots ?    The bulbs could be bypassed with a dual pole switch when limiting wasnt required . I can see with the simple 200 ohm pot method the load impedance of the source amplifier varies quite a lot dependiing on position of the dial ,that hampers the action of the lightbulb , so maybe the twin pot could form a kind of interactive threshold control between current through the bulb and limiting action on one hand and output level to the spring on the other .

Star, delta, bridge, t section attenuator ,theres just to much going on for me to clearly visualise whats happeneing to the impedences , maybe someone could explain better dual pot attenuators and how it might work inside a bulb  bridge .

The design load was 8 Ohms. The bulbs are 6.3V 0.95W, nominal 41 Ohms hot, perhaps 4 or 5 Ohms cold.

Why are you working to 200 Ohms?

And line-level? The design level was near 15V max.

Ive used a 6.3v pilot lamp in series with an 8 ohm speaker driven by a single ended EL84 , defenately plenty of current to light the bulb .  I had used a 200 ohm pot attenuator on another spring of a higher (600ohm) impedence , it works ok driven by by an opamp or with guitar amp outputs of lower impedence , in this case I'll have two  low impedence springs per drive channel , run off a new 6L6 /6au6 SE  with 4 and 8 ohm tapped OT .

This was the kind of dual pot I found , not too many values available 220 ohm 2x5 watt , or 100 ohm 2x3 watt seem the lowest .

https://www.ebay.ie/sch/i.html?_from=R40&_sacat=0&_nkw=WX250+double+5W+220+ohm+shaft+diameter+6mm+single+winding+wire+potentiomete+F8B3&rt=nc&LH_PrefLoc=2

I could  use two seperate controls , one  pot for the limiter circuit per channel  ,then another attn pot for each of the four tanks ,  just seemed like combining both into one and making the limiter switchable would be tidier , rather than two controls which will end up being interactive to some extent anyway .

Maybe a three way 2 pole on on on  toggle could be used to select single bulb limit ,dual bulb or attenuation without limiting independantly to each of the four tanks , Im making an assumtion that single bulb will clip only one half of the waveform and dual bulbs on  will sound different as both sides of the wave get 'lamped' . I could arrange my secondary winding centre tapped ,connecting the 4 ohms leg to ground and taking my outputs from 0 and 8 ohm taps , balanced to the limiter/attn/tank network ,  will that be of any benefit to me ?

I can arrange each stereo pair of tanks (two long and two short) as either two totally independant mono in stereo out with medium and long decay , or combined a short and long tank per drive channel . I might try  a small matrixed patchbay that allows series or parrallel and phase reversed drive , maybe the same arrangement on the recovery side for extra flexibillity . A few  positions of HPF on the drive end of each tank might be a nice addition , maybe passive treble cut on the recovery end .

I have a very large three unit 19inch box to house everything but the supply .so plenty of space and front panel real estate to play with .

Thanks for the interest Prr,

Seems to me that due to bad noise performance old style guitar amps tended to drive the tanks well into the point of distortion , with good low noise performance theres more low level detail to be extracted from a humble spring ,a lot of the metalic clatter you hear on vintage guitar amps is due to distortion from keeping the input level to the tank up to beat noise on the returns , I found with multiple springs a lot of the low end flutter associated with the spring sound can be reduced ,eliminated or canceled ,the result sounds a lot more polished and dense compared to a single tank thats been bounced around its whole life in the back of an amp.

Im surprised someone hasnt tried twin tanks in Fender style standalone, two four ohm versions could be driven in series from the standard 8 ohm tapping and maybe humbucking could be made use of on the return coils,  lim/att circuit could add a lot of extra tones to it as well , the secret for me is being able to distort  drive the amp section without blasting the drive end transducer into saturation , now you have second harmonic generation from your single ended output stage as much or as little of it as you like on your source ,without wobbling the spring all to hell and causing nasty core distortion in the transducers . Looks very much to me that the Akg springs use some form of feedback or maybe feedforward it could be called , to control the decay time , Ive used this  idea myself on a basic level where a spring driven by the aux 2 out  of a small mixer, its returned to a mic input channel  and added to the mix ,then using  the  aux  send,you add some of the reverb return signal back to the drive stage    ,it will break away into oscillation if its uncontrolled ,but even small to medium amounts  it noticably lenghtens the decay  density  and diffusion  ,  so its another very easy thing to add to the basic fender circuit, would only require a pot and a resistor or two. 

BiAmp made a rack reverb (140 and 240) which pulled out all the stops. Ample drive, sophisticated limiting, recirculation, fixed EQ, 4-knob EQ, metering....

It was OK. I can't think of any project where it was a must-have, or really $390 better than the $10 reverb that was still in many low-end mixers. It didn't suck, and I see used ones still fetch $400.

Oh thats an interesting one , the biamp ,
Theres lots of late 70's-80's analog gear around some of it surprisingly good .

I know its all a bit 'flahulach' driving a few springs with two big hungry SE amps ,but in any case I end up with a very nice general purpose speaker or headphone amp as an aside .

I think I'll just settle for the 100 ohm pots , seeing as theres two per channel that might equal 25 ohm load with an unfavourable setting of the controls , that will mean some loss of power to the load ,but I have tons of headroom to play with and I need to be able for instance to patch the output of a 50w guitar amp/speaker  into drive my springs if the need arises .