Axiom Home Page Forums General Discussion Stereo Yamaha HTR 5740 (6.1) for stereo in multiple rooms

Sorry in advance for a long-winded post. For my "secondary" system I have had a Yamaha 5740 with M22s and Velodyne CHT-8 in our living room and have been very happy. The receiver is rated for "POWER RATING 1kHz @ 8 OHMS = 6 X 100 WATTS, POWER RATING - 20Hz - 20kHz @ 8 OHMS = 6 X 85 WATTS" (copied and pasted from the Yamaha website). Due to geography/ease of use we wanted to use this receiver to drive speakers in our bedroom and on the outdoor deck by the pool as well. So, Friday we had someone (been in business 10 years, done work for several colleagues over that time with good results/knowledge, etc.) come hook up/wire the system through a 4 way switcher (would be happy if someone could tell me the correct name for this device) setting up 3 zones (living room, bedroom, pool - all speakers are 8 ohm, 2 speakers per zone plus sub in living room) and leaving one of the zones unassigned/speakerless. Since that time, the receiver has had the habit of just spontaneously cutting off if it is set anywhere near a high setting (it goes from -80 to + 15 and will cut off after a while at -15 which is not really that loud). I haven't had a chance to really check it out and see that it is all wired correctly (I'm typing this at work) but before I do I thought I might get some thoughts from the very helpful people here.
My thoughts/questions include:

We bought the wrong receiver for this purpose, but based on what was availble at the time that we were shopping with Best Buy gift certificates it seemed like a reasonably good receiver for a reasonably good price that would allow for possible expandability/backup for home theater and that 85 watts would be powerful enough to take care of any of our stereo needs. True?

Because my wife insists that the components (receiver and CD player) be put in the cabinet and the CD player is currently sitting on top of the receiver, it may just be overheating and I need to rearrange things to allow for adequate cooling?

Does having 6 speakers (although this problem happens with just one room turned on also) cause this type of trouble and if so is it because the resistance is too low - like trying to drive a 4 ohm speaker? Or am I totally confused?

If is not something simple like getting the CD player off the top of the receiver what is the best solution? HK 3480 stereo receiver? Separate amp? I'm open to suggestions.

I apologize for asking for help before I have really checked out some of the simple stuff, but it is on my mind and has raised some questions in areas that I would like to better understand anyway so I figured I would just go ahead and throw it out...

Thanks in advance.

I am NOT knowledgeable about this kind of stuff. But, I DO know, if the receiver's cooling vents are on the top of the receiver, having your CD player on top of it is NOT a good idea. Add in the fact that the receiver and CD player are in an enclosed area, and you have a classic scenario for an overheating problem. For sure, I would try rearranging before I made any other move. This, of course, assumes one can lock the wife in the closet long enough to get away with said rearranging and testing.

If the Cd player is sufficiently sturdy, you can place the receiver on top of it, assuming it will fit. That doesn't resolve the enclosed space problem, but it might be the first thing to try. If the wife continues to insist the components remain inside the cabinet, and if there is a back to the enclosed area, you might consider buying a small exhaust fan (similar to the one in a computer), cutting a hole in the back and mounting the fan in the hole to pull out the overheated air, thereby keeping things cooler.

But, the first thing to do is set up the receiver in open space and run it to see if overheating is, indeed, the problem.

Rockler sells quite a few different vent covers and a powered fan like Ajax mentions. If you determine that heat really is your problem and you don't want to ditch the cabinet, this might do the trick...

http://www.rockler.com/ecom7/product_details.cfm?&sku=6572&cs=1

Foghorn,

If you run any two pairs of speakers together with your switcher, the combined 8-ohm impedances will present a 4-ohm load (or perhaps even lower, if there are impedance dips on one of the speaker pairs) and Yamahas do not like 4-ohm loads. I think it's a combination of poor cooling and the low impedances when you run more than one zone. The thermal sensor would definitely shut down the Yamaha to prevent overheating, and I suspect the Yamaha also has a current-sensing circuit with current-limiting provision. So when it senses more current flowing to the lower impedance, it limits the Yamaha's output or shuts it down.

Domestic A/V receivers are not designed to drive multiple speaker sets in this sort of application. The advice on proper ventilation is sound. It might make a difference.

Regards

Thanks to all for the input. I will definitely try to address the thermal issue when I get home tonight. If that fails and everything else checks out, what receiver would be a good solution? I have a 14 year old Denon DRA-325 (50 wpc) in the garage that I will try next, but if I have to buy one I'm thinking of going with Harman Kardon or is there a better solution? Comments? Thoughts?

There are others more knowledgable (and some of them may also even be typing right now), but...

I'm suspicious of the "switcher". It seems like there are devices out there that somehow maintain a more benign load under such circumstances (Niles audio perhaps?).

Absent that, I'd try using that Denon to power the other zones - you may be able to feed the line in of the Denon with the line out from the Yamaha if there is not a more elegant solution. I'll bet that even if you power one other zone with the Denon, you'll solve the problem. I don't think you need a big, new, expensive amp to fix this problem. But then, I'm a cheapskate.

Fog, definitely get the CD player off the top of the receiver so that it has a better chance to cool. While running two or more speakers in parallel serves to reduce the net impedance(the sum of the reciprocals of the individual speakers equals the reciprocal of the total impedance, e.g. 1/8+1/8+1/8=3/8 or 2.66 ohms), you say that it shuts off now when even one set of speakers is connected through the switching device. Despite the experience of the installer, I'd question whether the connections are correct.

Thanks for all the input. By reading the owner's manual, I was able to find that there is an impedance switch on the back of the receiver - and by switching it to the setting suggested for 6 ohm or lower speakers I can play the receiver for many hours at reasonably loud volume (-5) in all speakers. I haven't had a chance to get into the cabinet and put the receiver on top of the CD player, but I have checked the receiver and it never really feels warm, let alone hot. I think I'll take what I've got and run with it - although I have one more question for the helpful folks here:

If I change to my 1990 Denon DRA 325 50 Watt stereo receiver, I will not have the option of connecting the CD player via the optical audio (toslink? - someone help me with the terminology here) connection. How important is this?

I believe the <6ohm switch just limits current to each set of speakers to avoid tripping the protection circuit.

As for TOSlink (optical digital) and SPDIF (coaxial digital) for your CD player (you used the right term) - probably wouldn't be so bad to just use the analog outs for any stereo/2 channel application.

Bren R.

Bren,

Is that why the 2 channel stereo receivers (HK 3480, Denon DRA 685) don't have TOSlink inputs? Because (and this may start another battle around here like the cable issue) when I bought a TOSlink cable and hooked my CD player to the Yamaha 5740 the sound seemed to improve significantly from the coaxial connection...