Stonehenge GPA build

[charles_hidalgo]

Quickie Hornresp sim showing just cab loading+impedance rise HF and at 100 W max rated power in 1/2 space with just 0.5 ohms series resistance for wiring, XO losses, so tube, Class A driven will of course be higher,rolling it off at 6 dB beginning at the notch if driven with a matching impedance (8 ohms).

Attachment 4447

I would love to know what this means... really . If it could be explained as if I were a five year old it would help.

Thank you

Charlie

[GM]

Quickie Hornresp sim showing just cab loading+impedance rise HF and at 100 W max rated power in 1/2 space with just 0.5 ohms series resistance for wiring, XO losses, so tube, Class A driven will of course be higher,rolling it off at 6 dB beginning at the notch if driven with a matching impedance (8 ohms).

Hmm, much too 'quickie' as the bold description is backwards, so ignore! 'Haste made waste' this time, so glad you questioned it.

Technically, measuring in 1/2 space is a speaker buried flush in a ~infinitely large outdoors 'billiard table' flat field with the mike suspended 4 ft in Altec's time (1.0 m nowadays) above the driver.

cab loading+impedance rise HF at 100 W sim shows the speaker's theoretical frequency response the mike will measure (woofer only) plus the woofer's high frequency roll off above the notch due to its inductance (AKA inductive roll off).

0.5 ohms series resistance All passive electrical components, circuits has some resistance in series with the driver from speaker wiring, XOs, etc., which in turn lowers the driver's effective efficiency (makes Qes, Qts higher, lowering damping factor), which technically makes the cab larger, tuned lower, though at 0.5 ohms not an issue with the large cabs Altec drivers ideally required; but couple it to a high impedance (Class A) SS amp or double its ohm rating with series resistance and it ideally requires the cab to be 2x larger tuned 1.414x lower, though if tube driven it interacts in a way that it creates a EQ that most folks find quite pleasing as it 'tracks' the driver's impedance, so the higher the resistance (lower the damping factor) the greater the 'smiley face' EQ.