AVR 791 shuts off with high volume peaks

Could be a problem with the wiriing, like a short. Or a bad speaker.

Or, I have read that some speaker's can present a difficult load that impedance alone would not account for (due to phase.)

-20 dB is not that loud though, not in my experience.

What do you mean by powered separately? You are biamping your left/right channels, in a 5.1 configuration?

Certainly you'll want to check for loose speaker wire from one post touching another post (either at AVR or the speakers themselves); however, the 791 is not designed to run 4Ω speakers as noted in the Owner's manual. Although it can generally handle them at average volume (ie -20db) levels, as you have experienced, anything above that will shut the AVR down in protection mode. For louder volume you'll want to consider upgrading to an AVR with preouts that can add an external amp.

For more information about your 791, check out the Denon 791 Owner's thread.

I believe that AVR is designed for 6 ohm minimum speakers. You might consider adding a 2 ohm resistor in each line.

They would need to handle 100 watts or so of power AND would be a total waste of power (which they would convert directly to heat.)

Not a good idea, iMO.

Wasted power, true, but 30W should handle it and the amp would not shut down.

I guess, but seems like a whacky way to solve the problem.

No offense, but why do people buy low-midrange receiver when they have 4 ohm speakers? I guess in the OPs case, he already had the speakers, and the replacement receiver is maybe not cutting it (but the problem could still be elsewhere, -20 dB is not that loud for movies, anyway.)

If you keep blowing AVR's and overdriving them I would recommend buying a power amplifier as it is obvious to me that you need one.

Mark

The problem is the 791..
It is built by Sherwood for Denon, it is capable of reasonable peak power but not continuous high power..
You can easily drive the 791 into clipping with the B&Ws and risk blowing one out.. Which most likely will not be covered by warranty..

You need to move up to a higher powered AVR or even a component power amplifier..

Just my $0.02...

How VERY interesting that Denon moved in that direction. Is the 791 the first unit this has happened from? Link?

Sherwood has been building the lower half of the Denon AVR lineup
(SRP < $899) for several years...
Except now the $249 entry (391) is actually built by yet another Chinese factory.

As the cost structure of the entry level AVRs has increased significantly due to higher royalties and HD components, so they have continually trimmed down the other AVR sections such as the power supply and amplifier sections...

For more details, check out the unit weight of an older Denon AVR to their latest models.
You will find this has been decreased by 30-40%..

Just my $0.02...

Really...This IS interesting. So the 789 is also Sherwood built? I mean, it really doesn't matter in the grand scheme of things as it is built to Denons specs and all, and I am quite sure the 791 is still better than Sherwoods own, comparable model.

I still would like to see the link that devulges this info as I would like more information. I know costs are lowered by using plastic faceplates instead of the solid aluminum type for example. And i was under the impression that as far as power supplies goes, the new 'switching' supplies as equal to if not better than the standard supplies? Just things others have reported is my basis for mentioning.

Denon's outgoing QA requirements are tighter than Sherwood..

Don't need a link..
I have been to the Sherwood factory in Shenzen China and seen Denon products on the product line. Note that other brand's products are built there as well including Yamaha, NAD, Teac, Marantz, Pioneer, Onkyo and Harman/Kardon.

Here is a link to the factory..
http://www.inkel.co.kr/english/newcompany/overseas.asp

Regarding switching supplies, the linear supplies are actually lower cost so these are used in the mentioned product category.


Just my $0.02..

Guess I should be pleased that my Denon was built in Japan then...

AVR production in Japan is rapidly disappearing except for the very high end..
Japan is too expensive especially with a currency exchange rate of 80 yen=1 US$..

Just my $0.02...

Try running the 791 and not bi-amping the fronts. Make sure the wiring is right and tight. Re-run audyssey.

Greetings!

I have been shopping for an HTS (my first one) and have been doing research on what to buy that will handle a pair of vintage Polk Audio SD II 4 ohm speakers that I acquired. After reading in various Denon threads regarding what the Denons can handle I bought the AVR 791 (just yesterday). I got the impression that if you didn't push too hard, most receivers (like Denons) would handle a 4 ohm load, and that they don't list it for < 6 ohms because doing so would require (a higher?) UL certification. I also bought a Polk CS-10 center 8 ohm to go with the set up. I have a pair of 16 ohms that I am thinking of hooking up for the surround rears, but have not done that yet. I have not bought a sub yet or chosen the other two speakers to complete the 7.1.

So, I have an AVR 791 with two 4 ohm Polks for the front R + L and an 8 ohm Polk for the center only, all connected with 12 gage bare speaker wire (until I get some banana connectors). I have not experienced any difficulties with the 791 shutting down or giving me any bad audio at all. The top of the unit gets slightly warm so far, but that is it. I have it connected to the HDMI sat/cab box, HDMI PS3 (also component to my Wii), HDMI XBox, HDMI BD LG blue ray---> HDMI out going to my RCA 1080p TV.

I have put it through the paces as it stands so far by playing all the game systems and TV and blue ray dvd (Batman's The Dark Knight and Cars for testing) as well as music CDs, ipod, and USB mp3s, and the radio tuner all at various volumes--including ~ -15 or so just to see how it handles. That was plenty loud enough for me and my kids, and the regular volume for us seems to be between -30 and -25, occasionally going up to -20 or so (but probably not too often). As I said, the unit so far has only gotten slightly warm on top (after several continous hours of testing).

We are still experimenting and trying to decifer the manual to see what other setting there are (such as tuner and audio presets, etc). I am always looking for helpful advice--I too, am a noob at Home Theater (on a budget). Any advice or thoughts on speakers for the SW, SL, SR, and/or other speaker combinations would be appreciated.