I currently have a Denon 2805 running a 7 speaker multi channel set up in my home theater. The L/C/R speakers have a rated sensitivity of 88, while the surrounds are rated at 87.5. The total system impedance is 8 ohms. The two fronts speakers are an MTM ported design with 6.5" woofers, and the center speaker is a ported design as well consisting of two 6.5" woofers, a single 5" midrange, and a 1" tweeter.

The Denon sounds very nice, but the problem that I am having with it is when I turn the volume up just past the moderate level, the receiver shuts down. This indicates to me that the 2805 lacks sufficient power to drive the multiple speakers for an extended period of time. My question is, will 3 M200 amps powering the L/C/R speakers with the Denon taking care of the 4 surround speakers take care of this problem? Or should I spend the extra money and get the 770 to power all the channels, and just use the 2805 as a pre/pro? I would rather go with the cheaper, 3 M200 amps, if that is feasable.

- Does this happen from a "cold start"?
- Is it possible the amp is overheating due to ventilation?
- Are all the speakers rated a 8ohms or some 4?

If not, the surrounds in movies take a lot less power than the fronts and center channel, so doing the 3xM200's should fix the problem. In fact even a 7100 should drive those speakers with no problem. Also you could drop a M200 on the center channel and try that first. A lot of the output hits that channel.

Both amps you have mentioned are rated at 200 watts rms at 8 ohms . This would be more than enough to run your speakers I would think .
Using either the M200 or 770 would give a sonic improvement to your system .

How do you have your speaker wire terminated ? This could be the source of your Dennon problems . The 2805 should be capable of driving your speakers as well . Granted the Dennon would not do as well as the M200 or 770 amps but it should not shut down when played above moderate volume . Are you sure you don't have a wire touching the housing of the 2805 . This would throw the rec. into protect mode if even a single strand of the twisted wire were in contact with the rear panel . You may want too check the speaker connections as well .

Thanks for the replies. No the Denon doesn't click off from a dry start. As a matter of fact, at the lower and moderate volumes, the Denon works fine and sounds good. It is only when I increase the volume above the moderate level that the receiver clicks off. The receiver has a lot of space on all sides, so I don't think that ventilation is a problem.

As far as some of the speakers being 4ohm, I suppose this is possible even though the system has an 8 ohm rating. This is what I first suspected as being the problem, but I am not sure how I can test each speaker for their impedance level. If this is the case though, will the M200's be able to carry the 4 ohm load at the higher listening levels?

I have the speaker wires connected to the receiver with bare ends, tightened down at the receiver's binding posts. I have double checked these connections, and they seem to be fine. If I did have a stray wire touching the chasis, wouldn't it short out at the lower volumes as well? Or should I eliminate this as a potential problem by connecting with banana jacks?

As a side note, I have a Yamaha RX-V2400 connected to my upstairs living room system. I brought the Yamaha down to the home theater and connected it up to see if that would work any better. However, the Yamaha did the exact same thing and shut down as soon as the volume was increased beyond a moderate level. I also noted that the internal fan in the Yamaha kicked on a lot as the volume was increased.

The center channel speaker is the largest speaker in my system, and since most of the audio output goes to that channel, do you think that a single M200 hooked up to that channel will take a sufficient amount of load off of the Denon, or should I just get the three M200's for each of the L/C/R speakers for the improved sonics and the free shipping when buying 3?

Thanks

Your speakers have a relatively low efficiency, which is clearly giving your receivers a challenge. The combination of this low efficiency and the fact that speakers' impedances vary (dipping below their rated values regularly, such that a "4 ohm" speaker may appear as a 2.5 ohm load on occasion or an "8 ohm" speaker much actually present closer to a 6 ohm load at times) is probably responsible for most of the trouble you are experiencing. An amp like the M200 will have a much easier time with those speakers - unlike receivers (which typically don't like dealing with loads that are less than around 6 ohms), the M200 can handle prolonged 4 ohm (or lower) loads at high listening levels.

Putting a single M200 on the center would help during most TV and movie viewing, but your mains are apparently not much easier loads to drive, so you may still want separate amplification for them as well for two-channel music listening.

After your last comment, I would agree with Gonk. It sure sounds to me like you are running low ohm loads through the receivers you have tested and thats why they are cutting out.

Most "cheaper" recievers are not really designed for such low impedence loads and its not uncommon to experience what you are seeing.

I don't think there are any Outlaw amps that are not designed to run at 4 ohms. Except maybe the 1050, which is discontinued.

It sounds like an impedance problem . MTM design speakers which utilize 6.5 in drivers commonly have sub 4 ohm loads often 3 ohm or less . The Dennon and Yamaha are said to be 4 ohm stable at best but it varies some what .
Most of the DIY speaker builders I speak with will tell you that MTM speakers that size can be difficult to drive . Stepping into a mono block amp will give you your best chance at solving your problems . Three M200's across the front would seem ideal for your setup . You could utilize the Dennon or Yamaha as a temp. pre/pro . to balance things out until you were able to upgrade .

trikos,my 1050 has a switch on the back for 4 or 8 ohm speakers

arntz,i was buzzing the manual to see if possibly the denon had such a switch,but no.
i'll jump on the bandwagon and agree you have a load problem and i noticed that the 8 ohm rating was full range 100w/.05%thd but at 6 ohm 135w/1khz .7%thd.so obviously the amp is struggling as the load drops.if i was able to afford amps for at least all 3 fronts,i wouldn't just amp the center

I had an Outlaw 1050 and build my own speakers and have for years.

The center channel speaker I was using ran a very efficient crossover design and scan-speak/vifa drivers which ran idiol at 3.8 ohms.

My Class A Bedini can drive them no problems, but it was on the edge for loud midrange scenes with the 1050 where the ohms dropped slightly (about 3ohms/2400hz)

Even though the 1050 was a great receiver for the coin, it was a bit much for it and once in about 20 movies it would give the relay a hard on..

i've only built car set ups(---back up slowly,slightly bowing down---)

gonna build my own center 4 a change...soon.