Denon DRA-685

[Kelly]

Recently used one in a retrofit with existing wiring, speakers (4pr), volume controls, etc.


I'll leave out all the specific job details, suffice it to say that I replaced a lot of the old stuff, and varified the load that would be placed on the amp.

Anything above about 40% volume level on the Denon would cause the unit to go into "protect" mode after approximately 20-30 minutes (And this in a very open cabinet with a lot of circulation).

I was not impressed....I've seen some rather low end AV receivers used in this manner really outperform this thing.

Possibly a bad unit, with a weak amp? Regardless, I'll not use one again.

[tomciara]

I know this may not meet with universal agreement, but I've had shutdown problems with impedance matching volume controls and used standard ones with a basic speaker selector box to fix it. I know others use lots of them so that's why I put the disclaimer on it.

[Kelly]

Tom,

This is the first time I've ever had a unit go thermal when using impedance matching VC's.

Besides, using a speaker selector is really just another method of doing the impedance matching that would/should have the same result. No?

With standard VC's and a selector you will still have a fluctuatiing load on the amp. And from what I've seen via meter, the load tends to fluctuate MORE in that type of setup.

[OEX]

impendance match and impedence multiplying are different. entry level switch boxes keep the load =>4 ohm regardless of pairs being driven. 4 impedence match could have the load <3 whicj would cause thermal shutdown. I always use regular VCs and use a Sonance SS4 or 6 in the el cheapo jobs. And using the switch box allows for real easy checking for shorts. just plug your ohm meter into the left input and check each left speaker one at a time then all 4, then do the same for the right side. takes less than 2 minutes.

[georgep]

Make sure the Loudness button is OFF.

We have had the same problem with the Denon stereo receivers. (now we use Integra) Turning the Loudness button off helped quite a bit. We were able to run up the volume a lot more without going into protect mode.

George P.

[tomciara]

Tom,

This is the first time I've ever had a unit go thermal when using impedance matching VC's.

Besides, using a speaker selector is really just another method of doing the impedance matching that would/should have the same result. No?

With standard VC's and a selector you will still have a fluctuatiing load on the amp. And from what I've seen via meter, the load tends to fluctuate MORE in that type of setup.

OEX basically summed it up. An inexpensive switch usually has a 3-4 ohm resistor in series, and yes it drops some power but it's still a good plan for basic installations. I've never had shutdown problems going up to 8 pairs but did with some of the impedance (matching, multiplying) controls.

And George, if the system is that close to shutting down that the loudness button is the trigger, I'd plan on a service call the first time the client hits the button. An amp shouldn't be that shutdown sensitive.

[WhiteVan Lifestyle]

[quote=Kelly]Recently used one in a retrofit with existing wiring, speakers (4pr), volume controls, etc.

Kelly,
I've installed a lot of Denons over the years and have to say they are one of the most durable receivers on the market. I generally run a seperate amp before getting into impedance matching or multiplying vc's. The problem you are having could be a bad or mis-set vc, or it could be a bad driver in one of your speakers, or since you didnt install the wiring, its very possible there is something going on there. I would tell you to be sure that all of your vc's are set to x8 but the fact that you can stand to play full volume for the 40 minutes it takes your receiver to kick off tells me you already need an external amp. I would look at all aspects of this before judging the Denon.

[vwpower44]

I have found that the entry level Denon stuff will not go below 6 ohms. As soon as you try to push a bunch of 8 ohm speakers through a speaker selector and VC's you are going to have problems. We usually use an amplifier in this situation.

[jrich]

I know this thread is really old however I felt like I had to comment. I swear by Denon and I have seen this problem many times before.

100% of the time it the power shorting out due to installation of the speakers.

I have seens the speaker wires touching each other which would cause this. Also if you are using ceiling speakers and there is metalic insulation above the speakers, if the insulation is touching the speaker that would cause this too.

Lastly, I have seen speakers mounted in a wall where the BX electrical wire was touching the speaker, that too will cause this.

It's not the amp, its the installation.

[tomciara]

Resurrecting threads over 1-1/2 years old violates your 30 day probation. You are gone.
















:D

[jrich]

I guess there are not too many posts in the public area, I saw it on the main page and then saw how old it was... I wont do that again :D