Does impedance of a speaker change when one bi-amps?

When I tried to run my ESLs off a high quality integrated I learned a lot. For instance the rated power is only deliverable into a resistive load. Anything reactive shut the amp down and a message came up "check for shorted speaker wires" That speaks volumes. The amp thinks anything below X ohms is a short.

Yep. ESL's are basically giant capacitors. 1/3 of an ohm at the top of the spectrum is not unheard of. Fortunately there's very little music power at 20kHz, but it is not an easy load in general.

If you are going to go with active crossovers, you seriously should just make your own speaker. DIY  your own speaker pair is something I think every audiophile should do at least once.

Build it from the ground up and learn what you need to do along the way, instead of this half baked approach.

For the record, almost all passive crossovers also include some form of EQ. If you plan to remove and replace a passive crossover you need to be prepared to do both.
And now I leave you guys to hack and play around.

Best,
E

Would my integrated be less likely to overheat at the same spl if I added a 2nd amp, removing the strap to horizontally bi amp the speakers?

Yes. Passive bi-amping would limit the current for the bass to only one of the two amps, therefore reducing the actual power drawn during the same musical performance as before.

also if I got output levels matched would amps of identical power be necessary

No

or could I wire a pair of 350 mono’s to the bass of each speaker and use the int to drive the top end?

Sure. An added advantage of this method is the ability to add EQ to the bass section alone, often a good improvement.

Best,
E

Bi-amping need not be complicated and difficult. And, it can be cheaper than replacing stock speaker-level x/o parts with those pricey boutique ones.

Really the only one’s who should engage in this are those who have speakers specifically designed with active crossover in mind (pro speakers), or who can build their own speakers anyway.

Everyone else is probably going to do it wrong and is far better off with a single amp solution.

Best,
E

Sorry, erik. BDP24 is correct. Individual drivers have rather smooth impedance curves because they are mass loaded drivers and thats what mass loaded drivers do.. The wild impedance variations we see in complete speakers are due entirely to the passive crossover which we want to eliminate.

You’d be correct if we were talking about active bi-amping AND removing existing filter sections which I did not believe we were.

WIth passive bi-amping we remove only the connection between the two filter sections while leaving the filters in place. In that context I was not incorrect.

I apologize if this wasn't clear from the blog posts I pointed to.

Best,
E

Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker

Sorry @BDP24 this is not really true as you put it. See from my blog post and any simulation, the min to max impedance is MUCH greater with a split crossover.

The overall current load however is always decreased. This may help the power supplies stiffen up.

While active bi-amping is good, it’s also complicated. It’s much easier to get top of the line parts and design in a passive. Do what you like, but it’s no free lunch. It is however preferred in pro environments as the dynamic range and amplifier to output is improved. Need less total watts for the same SPL.

Best,
E

Forgot I have a blog post for this:

https://speakermakersjourney.blogspot.com/2016/12/crossover-basics-impedance.html


Best,E

Assuming the crossover is split, yes.

So in a typical two way the tweeter impedance will go to infinity in the bass,
and the opposite in the woofer. The impedance will rise to infinity in the treble.

Of course, that "infinity" may be at 1 Hz and 1 MHz, so in the actual audible range you'll never hit it, but 30-100 Ohms maximums are not impossible.

If you want to play with this, using a crossover simulator like XSim and designing a very basic crossover will help you see what is going on.

Best,
E