Originally Posted by Heinrich S
Why do some manufactures design speakers that have impedances that dip down to 1 ohm, in some cases? I've seen floor standing speakers that have impedance dips down very low.
Back in the 1980s there were a few speakers that were stress tests of the amplifiers of the day. As I have documented in other posts, SS amp output devices are now 3-5 times more capable of delivering peak current even into reactive loads, then the first few generations of SS amps. And that is just the spec sheets, Reserves that used to be shaved are now overkilled.. Enough money has been made or lost on this issue that few are willing to build amplifiers that can't live with speakers or speakers that can't live with amplifiers.
There are now very few speakers that dip down to 1 or 2 ohms, but quite a few that dip down to 3.5 to 4.5 ohms. The only speaker I am aware of that dips down to 1 or 2 ohms does so at the extreme far end of the audio band where most recordings don't have much energy. I posted a detailed analysis of this a few months back.
Is this a design fault?
Yes. As rule not many people actually did it, it wasn't done in mainstream speakers very often, and just about everybody has learned to stop doing it in order to optimize their market position.
Was it intentional?
I can't speak in general, but I have had an over-the-web fairly close relationship with a consultant who designed a speaker like this for Infinity. He knew what he was doing but it was felt that people would pay for beefy amps to drive the speakers. This is one reason why amplifiers like the Pass Threshold SA4e came into existence. It was hard to short them with something that wouldn't disappear if you drove the amp hard. Basically, an audio spot-welder. ;-)
I don't understand why this is so, when there are also many well engineered speakers out there that do not have these abnormal impedance dips.
It is now very rare.
One good example is the Infinity Kappa range. Notorious for being extremely difficult to drive. Impedance dips down below 2 ohms. There are other exotic speakers out there that have abnormal impedance dips.
The Kappas have been off the market how many decades?
To the speaker designers, what are your thoughts?
Designing speakers that eat amplifiers or amplifiers that are easily damaged by speakers is a form of economic suicide.
One example of a power amp that was designed rather suicidally was the original Ampzilla. It had half
as many nearly identical output devices as the original Dyna 400, and later on the Dyna 400 was upgraded to have twice
as many output devices and sold as the Dyna 416. So the Dyna 416 had 4 times as many output devices of a similar type in a similar series-connected configuration.
Ampzilla 2 had 3 times as many output devices as the original Ampzilla. I can't tell you how the output devices in Ampzilla 2 compared to those in Ampzilla because the Ampzilla 2 used house numbers on those devices but they were later and therefore probably beefier devices.
Also, we don't know what was actually screwed into these legacy amps as built throughout the production runs, as we pretty much only have schematics for them. But they were probably initially built with the devices on the blue print. Same story explains why the later Phase Linear Amps were less likely to live up to the nickname "Flame Linear", not that some of them didn't blow., too.
See the pattern? Speakers got easier, amps got stronger, reliability ensued. We now hear about amps that shut themselves down, but not so many funeral pyres.