I never heard about it till now, you have educated me on that one Sir.
Reminds me (a bit) how the delay was done for music amplifiers before all this IC caper (showing my age now, I still remember when electronic semi conductors where diodes and transfer resistors).
I will not mention pentodes and our first portable radio "the 7 valve phillips" as mentioned in EPE mag by Paul Young (a.k.a Alan J Sproxton), I used to love his "Counter Intelligence" slot in that mag