Receiver Capable of Handling 4 Ohms - Page 3

Let's make it REALLY simple ...

Assume a loudspeaker system that has a sensitivity of 85dBSLP/1W/1m.

• Drive it with 1W and you will get THX Average Reference Level of 85dBSPL.
• Drive it with 100W and you will get THX Peak Reference Level of 105dBSPL.

That's at 1m distance in an anechoic environment. The THX spec is spatially averaged in an enclosed listening environment. The differences are practically irrelevant. Think the difference is important?? Then change the assumed speaker spec above to 91dB sensitivity or whatever turns your crank.

According to my own math, and assuming 2 meters listening distance from your speakers (or some of them anyway,) and assuming speakers with 90 dB sensitivity, you will need peak power of over 100 Watts / channel. In loud action scenes, with many or most channels average levels going very high, it would not surprise me if many receivers would clip under those conditions. And many powered sub's probably could not hit the peak 115 dB that is called for.

Just my opinion, because I don't have the gear needed to measure peak power. Too bad receivers don't come with clipping detection.

You may have read the Audioholics article on why all channels driven is not important. There's this idea that all channels are not demanding peak power at the same time, allowing your receiver's power supply some slack.

This is not scientific, but I measured peak levels in the opening scene in Sahara for each speaker (with the others muted.) I was surprised, that in some scenes, every channel was putting out high SPL peaks. So this idea that surround speakers are not very demanding may be a bit overstated. The surround peaks may have been down 2-3 dB which is certainly lower. But they were putting out plenty of sound.

So, depending on the movie, you may be asking a lot of a receiver to produce 102 to 105 dB peak SPL at every channel say during an explosion in the movie. I am pretty sure my Yamaha RX-Z7 can't do it! (And I know my sub can't)

And how am to shop for a receiver which can give me 100W of peak power? Or, maybe a better way to ask is: How can I tell what receivers do not meet this requirement?

Lots of receivers can probably give you peak power of 100 Watts to any given channel. But can they deliver enough power to all the channels as needed during peaks in movies? That's a big demand on a power supply.

Look at some of the current Yamaha receivers whose power consumption is listed at 200 Watts and weigh 20 pounds or whatever. Say the power supply can supply 400 Watts. Half that for amp efficiency. 200 Watts / 7 = 28 Watts. Maybe it can do double that due to the filter caps storing energy. Like 56 Watts.

My money is on the receiver clipping if you really want to try to reach 105 dB. Why you would want to, I don't know, as that's very loud. I would be happy with 95 to 100 dB peaks.

Interesting discussion.

For my setup I opted to use the pre-outs from my THX AVR (125W x7-Ch) to an external amp (185/4ohm) in order to let my AVR power just the 4 surrounds.
My two mains are 4 Ohm with 86dB sensitivity so I figured having a seperate power source for them would be a benefit & give my AVR a break...

That's interesting. How did you mute the other speakers? If you tell your receiver you're missing some speakers, it might route all the signal to the remaining speaker(s). I suppose you just disconnected the wires?

My receiver allows for muting channels. I am fairly sure it does not reroute sound. I am not sure what it's purpose is, because it mutes the pre out signal as well (IIRC.)

It would have made more sense if it just opened the speaker relay for that channel.

But you don't set the volume for peaks, you set it for main listening.

If you listen at 85dB (the THX spec) then the THX spec says you have to deal with at least 20dB peaks. Reality in movies (and lots of music) is that there are peaks of 25-30dB.

So if you want 100dB peaks without clipping and you're allowing for 25dB peaks (more than THX spec, but less than some content) you will be setting your main volume to 75dB which is not very loud.

The other thing to note is that the discussion of amp requirements here so far has talked about 1m distances. Most people are not 3' but more like 8-12' from their speakers so the power requirements go up accordingly.

+1. Great suggestion.

Sure it is Cavu says so, even if it doesn't have the THX certification. If you think the IPOD is a hoss, you should see what my 120 gig Zune player does. It powers my computer speakers to insane levels. As a matter of fact I'm going to get out Rat Shack meter and measure them scoundrels. I'll betcha they get to 85db with no problems.

That is correct. Get the speakers you want to keep for a long time. Then build your system from there. Get the Onkyo 707 or another AVR(THX certified or not) and if it doesn't supply the power you need add an amp when you can afford one. Amps are rated differently than AVR's, they will supply their stated power or come very close to it. Sorry your thread was twisted by others and myself. It can get complicated for some people who are just looking for sound advice and your thread turns into a pi**ing match.

So, how many amps out there double down when doing a 4ohm load that are suitable for HT use?
Lets see, Anthem MCA? No.
http://www.anthemav.com/products/ant...-series/mca-50

How about their upper line...Anthem Statement A series? No. http://www.anthemav.com/products/ant...r/a-series/a-5

OK, How about a Bryston? No.
http://bryston.com/9bsst_m.html

How about something NON Canadian, Maybe a Parasound Halo? No.
http://www.parasound.com/halo/

So, what kind of amp are YOU using that doubles down when presented with a 4ohm load? Not to slam Canadian anything up above, I have owned Anthem amps a BOATLOAD of Paradgim as well as Energy and WILL have a Bryston before its over...And lets NOT forget Crown Royal!!! lol
I would call all of the amps listed above VERY capable. There was a Bryston that didn't list a 4ohm load rating...It was a 28B....1000 watts.

My hearing is not great, and I can hear dialog when my receiver is averaging 75 dB in movies. That -20 dB on my volume setting, or so, which is fine. Of course movies vary

Depending on your location, you may be able to rent the AVR of your choice to give it a trial run on your speakers. Around Atlanta there are several rental sources that have Onkyo and Denon. If you do not need the external amp there really is no reason to spend the money.

I notice the encore tf's are rated at 92 db sensitivity. You should not need boatloads of power. In that price range check out the Harman Kardon 2600 or the 3600 both are rated at 4 ohm's.

You shouldn't have any problem with those MLs and any quality receiver. Onkyo, Denon, HK, Pioneer. Have you pondered an NAD. With a 4ohm nominal and a 92db sensitivity, you won't need a large external amp. (as was said above) Buy a decent receiver, hook it all up and enjoy the hell out of 'em.

Here is a cut and paste from the Futureshop Canada web site.

The Harman Kardon AVR 3600 combines ease of use with sophisticated features for the best in digital sound. With advanced surround-sound technologies including Dolby TrueHD, DTS Master Audio and Logic 7 processing, as well as Faroudja DCDi Cinema video processing with upscaling up to 1080p, the 7.1 channel AVR 3600 ensures an amazing surround sound experience.

Receiver Features
Banana Plug Terminals Yes
DSP Modes 11
FM Radio Yes
High Current Yes
iPod Connection Yes
iPod On Screen Display Yes
Multi-room Capable Yes, A-Bus
On-Screen Display Yes
Output - 4 Ohm Capable Yes
Output - 6 Ohm Capable Yes
Power Per Channel - Stereo 80 Watts
Power Per Channel - Surround 80 Watts

You can trust the H/K specs as they nearly always meet or in some cases from test reports exceed that spec. They are one of the few that do that. Their amp sections seem to be rated conservitvely. Check out the dedicated thread for the 1600/2600/3600, to see what owners are using for their systems. I'll bet if you ask your question about your speaker choices there someone will chime in they are using 4 ohm speakers with no problems.
http://www.avsforum.com/avs-vb/showthread.php?t=1178816

These Onkyo's are normally set to 6 ohm and above performance. They are also capable of changing it to 8 ohm settings in the menu. My 876 does not have a switch on the back of it to switch from 8 or 6 to 4 ohm setting, that I've noticed. Certified 4 ohm performance means that it is capable of driving 4 ohm speakers. I suggested this AVR because of two reasons. 1st being its capable of adding an amp in the future if you should want to. 2nd being Audyssey Multi EQ instead of just EQ-2. THX is also a plus for some of us. But we are not going there again. This AVR should be able to do what you want with the speakers you ordered. If it doesn't meet your satisfaction, save your nickels and dimes and order the Emotiva UPA 5/7 or the XPA3. The XPA3 for the fronts will drive those speakers easily and you can use the AVR for surround duty only. The UPA5/7 should also do the same. This will leave you open for the mentioned options in case you feel you want more power in the future. Good luck and enjoy.

Not exactly sure of Onkyo's terminology choices but if you look under the specifications tab, in the amplifier section, you'll see that speaker inpedance is listed as 4-16 ohms OR 6 to 16 ohms depending on whether you set it for 4 ohm or 6 ohm and above speakers.

If they didn't think that some would use this AVR continually with 4 ohm speakers I don't think they would give you the option of setting it up that way.

This one doesn't either, you have to select the 4 to 6 ohm setting in the menu.

Thank you for clearing that up. I'm not familiar with the "newer" model Onkyo's and their setup. I'm still stuck with that "old" 876.

My "old" 703 has the 4-6 ohm selection in the menu, click the setup button, toggle to speaker set up, toggle to options.

Your's is the same. Page 61 in your manual.