Impedance Phase angle

[jmb]

I have built a fair number of speakers but never really concerned myself with Impedance phase angle other than trying to keep it within the +/- 40 degree range, though, I must admit, not all of my designs have successfully accomplished this though I was more attentive to keeping above 4 ohms. I understand that there is a real component to the impedance (Imp*Cos(theta)) and an imaginary portion (Imp*Sin(theta)) and I also understand the Power Factor. What I do not understand is how important this is with solid state equipment; i.e., need I concern myself with any of this or is just keeping the total Impedance over 4 ohms or so for a decent amp acceptable?

[GranteedEV]

Re: Impedance Phase angle

What I do not understand is how important this is with solid state equipment; i.e., need I concern myself with any of this

It depends on your amp, and also the frequency at which the phase angle is too extreme. Yes some solid state amps can oscillate with too reactive a phase angle.

the key word is "some". if you take a look at this {arasound amp, while it is in fact current limited at lower impedances, it is mostly unaffected by the phase angle:




but it is not a representative of just any solid amp.

Generally a good amp will be stable, but the more inexpensive amps not dedicated to driving high end speakers may fall apart with the same load.

[jmb]

Re: Impedance Phase angle

Thanks. And, of course, it all depends on how hard you drive the amp. It's also amazing how much strategically placed RL shunts can help.
Jay

[PWR RYD]

Re: Impedance Phase angle

Jay, I hope this isn't a hi-jack of your thread but more of an expansion on the minimum impedance and phase angle questions....

I read a lot on here about impedance friendly designs and how this receiver or that receiver will shut down or not like that load. Is this more of an issue with really new HT receivers? Do they imploy more stringent protection? The reason I ask is that I have two receivers that I use frequently. One is a HT Yamaha RX-V850 that I purchased in about 1992 and the other is a really cheap 2 channel Sony STR-DE197 that I bought on clearance at Best Buy for only $99 around 2002. I can't remember their exact specs but neither have ever shut down or had a problem with any of my speaker projects. The "Trials" for example are a 4 ohm nominal 3 way design that dips to a dangerous 2.9 ohm impedance down in the low woofer frequencies and again in the midrange. I have cranked them for hours and yes they get a little hot... but have never shut down.

Am I just lucky? Am I on borrowed time? Any thoughts?