Passive crossover

[joyspring]

So,to ask the next question, has anyone used simulation software to check the veracity of the circuit I posted? You gotta remember when it was designed ,using relatively standard methods. I don't think it could get much simpler.

No one has performed any calculation because there is no point.

I mentioned that passive networks like this were designed in the era of 600 ohm termination which optimally used transformers for impedance matching (max power transfer), isolation and - most importantly in this instance of tuning a L-C circuit - ensuring that the target bandpass / bandstop frequencies are met.

This circuit uses resistive termination without buffering (isolation) which is NEVER recommended and will NEVER meet target -3 dB points in real circuits. In other words, it won't work.

Thankfully we live in a world where solid-state electronics offer low output / incredibly high input impedances and we have finally moved away from power (0 dBm = 1 mW into 600 ohms) to simple, scalar voltage (0 dBu = 0.775 V) reference for equipment interface. And we have finally dispensed with obscenely expensive phase-altering transformers!

I did look at the L-R blurb on Elliots web pages, and it seems his thoughts are well respected.

His thoughts are well respected because they are based on solid audio engineering principle.

Is one really going to hear, say a 3 db differenced at the crossover point knowing full well that most speakers can't spec their entire range inside of 3 db?

Depends on where (frequency) and over how broad a range (bandwidth) this 3 dB difference is -- please study the psychoacoustic concept of Equal Loudness (Fletcher-Munson / Equal Loudness Curves).

But in general, yes, a 3 dB difference - particularly in the midband where most crossovers are designed to operate - is audible.

This was simple, had few parts, had to deal with only small voltages instead of lots of power, and I don't think there is any preamp out there worth its salt that can't handle a 3 db insertion loss. ???

Yes it is simple because there are critical features missing. Without an exact load or buffering/transformer isolation from outside reactances, this design will not work as intended.

And never mind the insertion loss; it is the poor transfer function (frequency and phase response alteration) that is objectionable.

BobR