ohms

[Thepope]

whats the difference between a speaker with 4 ohms compared to a speaker with 8

 

[ruadmaa]

What's the difference between 4 & 8 ohms

Exactly 4 ohms. I am not being facetious, there is absolutely no difference in audio quality or anything else whatsoever. The 4 ohm will draw more power at any given volume setting than the 8 ohm speaker and that's about it. If you want the 8 ohm speaker to play just as loud simply turn up the volume a bit.

 

[20to20K]

To be a little more detailed...

The difference a 4 ohm speaker would make on your system compared to an 8 ohm speaker is the amount of strain it will put on you amp/receiver. Many AVR's specifically do not recommend 4 ohm speakers because they could cause overheating and subsequent shutdown of the receiver. If you have
(or plan on getting) 4 ohm speakers you may want to consider also getting a seperate hi-current amp to hook up through the receivers pre-outs. This is
especially true if you plan on running 5 or more channels.

I have a mixture of 4 and 8 ohm speakers in my systems. Three 4 ohms up front and two 8 ohms in the rear. My Denon 3805 is CAPABLE of driving all 5 channels (and I allowed it to for a while) but then I bought a seperate 2 channel, high current amp for two of the 4 ohm speakers and it made them sound better and took a huge strain off my $1200 reciever.

8 ohm speakers are a lot easier to drive. But the previous poster is correct.
There is nothing inherently superior in a speaker based on impedence. There are plenty of great sounding 4 and 8 ohm speakers and plenty of both that sound like crap. However I find that 4 ohm speakers typically need a high current amp to sound their best. This wasn't as true (IMO) for many of the 8 ohm speakers. A seperate amp made them sound better...but not as dramatically as with 4 ohm speakers.

 

[dillweed]

This was talked about in great detail here:

http://forums.audioholics.com/forums/showthread.php?t=7014

 

[Starmax]

RE: 20to20K's "To be a little more detailed"

I have put together a similar set-up to 20to20K's system - Polk Lsi15 fronts, LsiC center, Denon 3805 Receiver running the center plus 2 back surrounds, and a 2-channel amp driving the fronts. The only differences are our power amps (mine's a B&K Reference 200.2), and surround speakers (I have two Polk RTi12’s in the back). I mostly listen to music (SACD's & DVD-Audio/DTS played on a Denon 2200 Universal player), but also enjoy movies.

"Amen" to his observation on the difference using a separate, 2-channel, high current amp on the two fronts makes! Not a life-altering difference (the 3805 did fine by itself) but significant enough that I can detect subtle enhancements in mid-range detail & clarity. The most noticeable difference is the boost it provides to the Lsi15's woofers! My Kliptsch RSW-12 Sub is getting lazy and out of shape these days, especially when "LFE/Mains" is selected, and this is with the crossover set at 40Hz.

Now I'm obsessing over those four 120w. amps being unused on the 3805! Would there be any benefit to passively bi-amping each of the back RTi12's since the 3805 reciever is bi-ampable? I'm already bi-wiring each of my speakers. How about bi-amping the center? As much as I enjoy spending time trying out different configs., am I totally wasting my time here? Would it make even a tiny bit of difference?

Some idle speculation... I chose my components based on getting the best stuff I could get and still stay on budget. Since Tweeter was running a “24-month no finance charges” deal, I was a little more extravagant with my selections then when I started out. It occurred to me that the similarity between my set up and 20to20K's is more than coincidental. I'll bet there's a lot of virtually identical Tweeter-inventoried configurations out there in listening land, because the no-penalty offer made those items more accesible to more people than using a credit card for internet purchases, even though the selection is far greater and sells for less. Anyone buying my theory?

 

[RLA]

V=IxR

 

[20to20K]

StarMaxx hit it on the head...

I got all my gear from Tweeter and have already taken advantage of that outstanding upgrade policy. I've got the 3805 but I originally had the measley 2803...when I saw they had a 3803 on demo for $10 more than I paid for my 2803 I used their upgrade policy to get it...for $10. It gets better...the 3803 was a dud. I would shut off while running in 5 channel mode. At the time I only had the LSi15's up front so I didn't realize this until I got my surrounds and center(about 6 weeks later). By then they had no more 3803 at any Tweeter on the East coast...they had to give me a brand spankin new 3805 as a replacement. My cost? $628. They sell it for $1199.

Now I'm sure the fact that I bought all my Polk LSi's, my Denon 2200 Universal, Velodyne sub, and all my cables and bi-wires from them helped my cause, but I still ran out of there with that box as fast as I could so they wouldn't change their mind!

I've heard mixed reviews about bi-amping with the 3805 (read Clint Deboar's review). Reports are that you may hear an audible hiss during quiet passages. I haven't tried it myself, but it's something to listen for. I've already paid a pretty penny for bi-wire with single termination on the amp end so I'm not about to give Monster anymore of my hard earned money! The way I look at it is those extra unused channels are relieving strain off the 3805 and keeping it nice and cool. It's still running one 4 ohm and two 8 ohmers and if I ever go
7.1 (hit lotto and get those LSiFX's) I can put the 3805 into heavy duty
mode again until I get another seperate for them.

 

[Starmax]

xtra speaker juice...

Ok 20to20K, I understand your concern about overdragging the 3805 by driving all the channels, but how about using just one of the amps to bi-amp the LsiC? I've done the bi-amp trick before when I had Rti12's as fronts and it worked fine. No hiss or buzzing, and even though the improvement wasn't earth shattering, it was noticeable. Clint Deboar's original instructions on bi-amping the 3805 were confusing and I never could get it right. He updated the instructions a few months later where he went into more detail on the Source Selection procedure (which I was doing wrong) and also suggested using "zone 3" instead of "zone 2" for the Power Amp Assign. I'll try it on the LsiC some rainy weekend and let you know if it's worth it (think it can handle 240 watts?).

 

[20to20K]

Biamping just the LSiC would certainly be less straining that both 15's...especially considering I have the 15's set for large and the LSiC to small...so it's definitely worth a shot. Biamping both of your RTi10's was basically the same deal I suppose since those are 8 ohm speakers. If I understand how it works, bi-amping one 4 ohm speaker would put the same extra strain as biamping two 8 ohms speakers in the same setup. If that is true then you have some historical data to consider. Sounds like you should be OK. Let me know how it turns out!