Bi Wiring Speakers from Luxman L-509X

Then answer me this what happen if the two frequencies are hit at the same time, What does the amplifier see then? It seems the sim is showing the the two different frequencies but not at the same time.

I'm sure there are a lot of fancy terms, I've left out, leaving out or just don't know, but a speaker crossover? I suppose they are complicated, but they sure don't have to be, by design or by explanation.

I'm seeing what happens in the sims I'm just not understanding in the music world how this equates.  Aren't different instruments being played at the same time? 

I also see super high ohms in certain regions, Wouldn't the amp see just that and be down XX db without a notch to bring the impedance down and volume UP. These are about as simple as can be to me, but it sure is being made complicated. I understand the port (s?) or two XO points, I use passive radiators, to change the Q. By design a lot of the XO in the sim is really limited.

But that simple XO in a real speaker isn't gonna look like that is it?

I don't run simulators, I don't build XO from scratch. I use a Quasi second order filter for everything above 300hz.

In my XO building I use the same basic drivers and have for 35 years.

Erik while your simulating, I'm replicating. I use to turn out a mid/high pass in 30 minutes.. Before the night was out I'd usually have 2 or 3 filters built and make my choice after a couple of swaps and listening sessions.. Add a LPad or two or three.

It's been 10 + year sense that time.. Maybe simulators are better, I don't know.. By the time I fiddled with the software, 3 days have passed.. I could have made 10 XO by then..  A DCX 2496 is just to easy to actually run the crossover I like and build from there. With over 100 different types, I still stick with ONE certain type. Software/hardware sets.. I find it a pain in the A$$ LOL

I enjoyed the read, but my notes are scribbled in a binder 50 years old now.. AND in left handed code..:-) I'm pretty analog lets say.. Only so much band width to play with.. :-)

Think Forest Gump... a good solid 80 IQ, I'm thick but my hand were quick..

Then answer me this what happen if the two frequencies are hit at the same time, What does the amplifier see then? It seems the sim is showing the the two different frequencies but not at the same time.

Lets assume an ideal 8 ohm tweeter and mid-woofer, with a perfect infinite slope crossover at 2 kHz. So perfect that at 1,999.99999999 Hz 100% goes to the mid-woofer and at exactly 2kHz it all goes to the tweeter. You would have an amplifier load that is exactly like a single, ideal 8 ohm driver without a crossover.

We know that current = V/R, but how would we ever calculate the current for complex music?

Imagine a test tones with two notes, 500 Hz and 4 kHz. 8Vrms each, with the peak voltage 2x the peak of either by itself.

In this case we have 2 A, because you take each section and add them.

8 Vrms @4kHz / 8 Ohms = 1Arms tweeter
8 Vrms @500 Hz / 8 Ohms = 1Arms mid woofer

Now imagine we use the same test tone and add a true woofer below 200 Hz, converting into a 3-way:

8V / 8 Ohms = 1A tweeter
8V / 8 Ohms = 1A mid
0V / 8 Ohms = 0A woofer

We added a 3rd driver, but the current did not rise. Calculating a total R of of 8/3 will not work here.

Let’s this time use a new test tone at 200 Hz but nothing else.

0V / 8 Ohms = 0A tweeter
0V / 8 Ohms = 0A mid
8V @200 Hz / 8 Ohms = 1A woofer

Again, the current is entirely dependent on the section it went to. In all of these cases, the answer is that the current and power is identical to a single driver because of the magic brick wall filter sections used.  Real filters are not ideal, but not too far off these examples we can't use them, and where the impedance curve drops to the impedance of the single driver you can see it is working very much like these examples.

Of course, multi way speakers and music is complicated and ideally resistive drivers almost never exist, and never match other driver types. :D You can’t really do this with music without a digital sampling mechanism, but i hope you can see that no, the drivers don’t add up the same way in an AC circuit with filters.

In the post I sent you I use a VERY typicical type of speaker build and crossover design, one you’ll find 100s of examples of in Stereophile. That peak between the mid and tweeter is the combination of the low and high pass filters. Split them apart, they go to infinity. Put them back together, either with jumpers at the speaker or bi wiring to the amp, and they meet in the middle at an amount a lot less than invinity, but a lot more than either driver.

That’s how marantz recommends to connect when bi wiring....A for low frequency driver, B for high frequency driver....or vice versa.....there is no detriment...on my sugden, it only has one set of speaker outputs. I use both spades and bananas on the amp end to connect two equivalent pairs of Audioquest type 4 cables, 4 meters in length. A Stereophile recommended cable for a very long time...like the 1980's....

Thanks for taking the time Erik.. Always interesting..

Regards

I also see super high ohms in certain regions, Wouldn’t the amp see just that and be down XX db without a notch to bring the impedance down and volume UP.

@oldhvymec

Speaker output is proportional to voltage, and we assume an amp acting as a voltage source with little output impedance, so long as the speakers impedance is high enough ( say > 3 Ohms), raising the speaker impedance to a very high amount like 100 Ohms wont alter the voltage.

Here is one of hundreds of examples of a two way speaker with that xo hump:

https://www.stereophile.com/content/polk-legend-l100-loudspeaker-measurements

Notice the xo impedance hump is not present in the frequency response plot.

There are speaker designers who take more care in order to appeal to tube amp users, like Fritz, and they take extra care to avoid that xo hump. In Fritz’s case, he does so by using serial xo. Others may add an impedance compensation circuit, but since they soak up watts they are big and expensive to make.

But that simple XO in a real speaker isn’t gonna look like that is it?

The first plot on the post i shared was a simulated XO, but the actual XO measures (via DATS v 2) nearly identical so it is absolutely not worth posting. It is the same curve. The trick to getting the camel humps right is to measure the woofer in the cabinet with the port in place. The last two curves in my post are for simple first order filters so you can see how rising impedance blocks unwanted frequencies.