SDA Blade-Blade interconnect/crossover question?

JayMX
JayMX Posts: 446
in Vintage Speakers
Please don’t roast me too hard for asking this question hopefully I’m not too dumb asking... I did take quite a few electronics classes back in college but I’m not quite sure I understand the circuit on the SDA Blade-Blade crossovers. I get that the dimensional drivers are out of phase with the main drivers. I also believe that only lower frequencies (under 2KHz?) are passed through to the dimensional drivers. That said, I did some searching on the forum and I couldn’t find where anybody asked this previously...

Here's my question: Why one couldn’t we just use two isolation transformers, one on each conductor of the interconnect?

Would all you smarter guys please chime in and help me understand what’s exactly happening between the crossovers on the dimensional circuit?

Thank you in advance!
Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (4x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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Comments

  • pitdogg2
    pitdogg2 Posts: 25,441
    I'm thinking because both blades pass full signal back and forth. On the pin blade only the pin passes signal and the blade goes to ground and is only used in the case of mono's or none common ground amp topologies.
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  • JayMX
    JayMX Posts: 446
    I understand that the pin blade versions only use the pin for the dimensional signals and the A1/dreadnaught transformer accomplishes inductive coupling on that single conductor, correct?

    So that’s my thought - why not use two toroids, one for each conductor of the blade-blade interconnect? Would it not work because there wouldn’t be a ground path for each transformer?
    Current Collection: Monitor 4a (Peerless), Monitor 5B (Peerless), Modified Monitor 7b (Peerless), RTA15TL (SL3000), SDA CRS+ (194’s), SDA SRS 2.3TL, R100's, R200’s, R300 🤩
    Pairs that have passed through: Monitor 4b (Peerless), Monitor 5a (Peerless), Monitor 5b (SL1000), Monitor 5b (SL2000) (4x pair), Monitor 7b (Peerless), Modified Monitor 7c’s (194’s), Monitor 10a (Peerless), Monitor 10b (5x pair), RTA8, RTA8TL, RTA 11T, RTA12c (194's), SDA CRS, SDA 2 (2x pair), SDA 2a, SDA 2b, SDA 1b, SDA 1c, SDA SRS 2 (2x pair), SDA SRS 3.1TL (198’s) (2x pair)...and more to come, it’s a sickness.
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  • F1nut
    F1nut Posts: 50,546
    No, when using the AI-1 or Dreadnought both the pin and blade are used. The blade is connected to the negative circuit.

    The blade/blade connections flip at each speaker. The postive on the right channel connects to the negative on the left speaker and vice versa.
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