I ran all new speaker wires for my home theatre yesterday. And just to make sure that there are not any short circuits, I got out my multimeter and tested all the connections before I hook them up to my amplifier.
I learned that my rear speakers are 6ohms. Nice.
But my front speakers have me quite confused. They can be biwired, so I ran two separate runs of speaker cable. When I tested two of the wires, I got 8 ohm resistance. Fine. But the other two wires gave me NOTHING. I checked that the wires were hooked up.
So next I touched the leads of the meter directly to the speaker binding posts. I get a reading on the lower two binding posts. But not the upper two. Does that mean that my speakers are not really biwired at all, and that all the signal just goes through one set of binding posts?
I'm confused. Please help. I suppose I can test it out by running signal through one set of binding posts at a time.
10-15-2004, 06:06 AM
It's not unheard of for a speaker to look as though it offers bi-wiring, but in reality it doesn't. More likely to be found on a 'white van'* speaker, but can occur with speaker brands who are less than full of integrity.
Many speakers don't offer any sonic benefits from bi-wiring, despite their insistance on providing the option. Bi-amping is more likely to make a difference, but generally, that's more to do with the overall increase in power, rather than a division of crossover feed.
If you really want to give your speakers the best feed, by-pass the internal crossover and fit an external crossover between the pre and power amp.
* - White Van speakers are garage-made low-end speakers bought from some nutter in the back of a white van feeding you a crap line such as: "We were sent too many pairs for the job we just completed so we're letting them go really cheap. They usually go for $2k, but you can have them for $350."
They aren't even worth $350 and usually are branded with a generic name such as 'Acoustic Audio' or 'Studio Digital' etc.
10-15-2004, 06:11 AM
10-15-2004, 06:21 AM
Funny you should mention "white van" speakers. I was speaking with MattK the other day, and he made the same inference. I know all about White Van speakers -- my friends and I have been laughing about them for many years.
My speakers, however, were purchased directly from the mfr several years ago by an audiophile friend of mine. THey are built VERY well, and use some of the same internal components as ProAc speakers.
When my friend graduated to something better (PSB Stratus Gold), I bought these bookshelf speakers from him.
When I went shopping for a matching center speaker, I brought one of them to the store, and the salesman was quite impressed by the design, build quality, weight, and of course the sound. We eventually matched it with an NHT center speaker after trying out every single center speaker in the store (about 15 or so).
Their sound is quite impressive -- I put them in the same class as ProAc Response 1s or PSB Stratus Minis. I can make that comparison because the friend I bought them from also had PSB Stratus Minis for a while. Sonically, they are similar to the NHT SuperAudio series from a few years back (that's the center channel I got).
I have used them for several years in a variety of audio and home theatre applications. In my audio system I had biwired them. In my home theatre I had never bothered to biwire them. But since I ran all new wires to my home theatre, I decided to biwire them. And the only reason I made my discovery about the upper binding posts is that I was using my multimeter to check for shorts.
I suppose I'll open up the boxes sometime and have a look inside...
10-15-2004, 06:48 AM
Perhaps they only have one type of terminals they purchased for all their speaker models - and left the top terminals open for this model.
Also, I hope you know that the resistance you measured 8 ohms - is not the impedance of the speakers. Impedance is a dynamic measurement of the inductance of the speaker and not the dc measurement of the resistance. I think you said the speakers were rated at 6 ohm impedance.
10-15-2004, 06:55 AM
10-15-2004, 06:59 AM
to your amp/reciever.
10-16-2004, 02:30 PM
10-17-2004, 10:12 AM
10-19-2004, 06:09 PM
Don't freakout, your fine. Agood thing to do while your at it is to take a 1.5V AA battery and touch the speakers leads with it. If hooked up right, the woofer cone will come out away from the speaker, if it gets sucked back, your polarity is reversed.
10-19-2004, 06:13 PM
Good speakers will either give you a chart depicting impedance vs. fequency or at least a minimun impedance. Don't freakout when you see the graf, near the bass it can swing from 2 ohms to over 40, yet still be coined an 8 ohm speaker. Tottally normal.
10-20-2004, 07:12 PM
I had also sent an email to an AWOT "old timer" JamesR. who designs audio systems for a living.
His response was right in line with what you said. In fact, for anyone interested, here's what James has to say:
He also attached a sketch of the signal path, although I am not including it here.
Inside of your speaker there are crossover networks. If it's a two way as I've drawn you'll have a woofer and a tweeter. They get low pass and high pass networks attached to them respectively. The components of the 2nd order low pass network are a series inductor (looks like mmm with a two bars over it) and a shunt cap. I dunno how much you know about electronics, but an inductor is basically a spool of wire wound in a special way that causes it to reject currents of a high frequency while passing those of a low frequency. When you attach your Multi Meter the current flows thru the inductor, thru the speaker and back out the other terminal thus allowing you to measure the resistance.
The Tweeter has a high pass network which consists of a series capacitor (looks like --||--) and a shunt inductor. Capacitors will not pass DC, they block it. They will pass AC, but they favor currents of a high frequency rather than low. You could say a capacitor is the exact opposite of an inductor. Because it blocks DC your meter cannot make a current reading because to it...the circuit appears to be open. In reality it is not...at least not for AC which is what audio signals are...alternating current.