# No sound from Denon POA-800's switched mono



## cwsanfor (Aug 8, 2013)

This may be marginally in the right place, but I accept criticism well if so.

I bought two Denon POA-800's to augment my Denon AVR-X4000 (driving the Front Wides). Got them from Ebay from a respectable seller. They are just the size I want. However, when I replaced the Sony receiver I was using to drive the FW's, I got no sound.

I believe I had the amps wired correctly:

Mono switch on
Power on (g)
A single RCA cable from the pre-amp out of the AVR-X4000 to the Left input on the POA-800s
The speaker wires to the topmost (Red) speaker jacks on both POA-800s, per the Service Manual.

The seller seems straight, has corresponded with me several times, and I find it a little hard to believe both amps would be bad, though it is possible. I tend to think it is something I am doing, though I can't see what. I have a SquareTrade warranty, and will troubleshoot further with a CD player and some spare speakers, but does anyone have any ideas? I looked into one of the POA-800's and there is no obvious capacitor bulging or anything, and no burned smells.


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## JohnnieB (Jul 1, 2013)

Hi cwsanfor. to be honest, I'm not familiar with the poa-800s but, grab a pair of female to male y adapters and use both inputs on each amp. just a thought. it could be as simple as the 800s need both inputs to run. ill look them up when I get home and see if I can help further. good luck.


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## cwsanfor (Aug 8, 2013)

That's what Denon Tech support suggested earlier this evening, as well as trying one in stereo mode. If it worked that way, it would suggest that the amp just needs to see two RCA inputs. The Service Manual does not look that way, but it's about as old as my eyes. 

I've never hooked up a pure amp before, maybe this is a common thing. 

Thanks.


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## JohnnieB (Jul 1, 2013)

Anytime. Enjoy!


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## AudiocRaver (Jun 6, 2012)

Is it a European model? Will it work on 120V 60 Hz? Is there an AC voltage select switch? Things to check.


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## cwsanfor (Aug 8, 2013)

US, 120V, no power selector.


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## AudiocRaver (Jun 6, 2012)

Any luck running in stereo mode? Definitely try that before anything else.

If so, in mono mode only one input should be needed, probably left, but try right, too. One or the other, probably not both.

Does the stereo/mono switch click firmly, feel like it is engaging properly? Speaker connections are between the two + terminals on each unit, right? Can you post a rear-panel pic?


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## cwsanfor (Aug 8, 2013)

Tried it in stereo, no joy. Put the Sony back in, it worked. I got the service manual, will check fuses and such, but am exhausting my skill level. I fear that SquareTrade will just write me a check for the $99 purchase price, and I <really> want these amps, but so it goes.

Yes, it's hooked up correctly, top reds in use. I'll try to post a pic later.


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## AudiocRaver (Jun 6, 2012)

Stereo operation should be super easy, and it sounds like you are on top of everything that should be done. Hate to say it but they both sound DOA, as unlikely as that seems. Cable problems? Do you have a way to verify cable continuity (can you/have you already with your Sony?)?

It is a bummer to get a new toy and have it not work.:sad:


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## cwsanfor (Aug 8, 2013)

It's certainly a First World problem, I'm keeping it in perspective. However, there is basically <no other> amp I want in there. Right size, color, make, wattage. I may get out the soldering iron. The parts in there probably don't cost $10 total.


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## AudiocRaver (Jun 6, 2012)

Sounds like you have some serious skills. With a voltmeter, you can check power supply voltages, etc. Also, the free version of TrueRTA has a very capable sound card based audio-frequency dual-trace oscilloscope that could come in handy. Good thing you have that service manual.


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## cwsanfor (Aug 8, 2013)

Thanks, but I'm just a hack with a multimeter. Excellent tip on TrueRTA, I have a number of uses for that.


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## JohnnieB (Jul 1, 2013)

I cannot seem to find a reason that the sony would work and not the denon. You probably tried this but maby try turning the sub out level up. Max setting? I'd hate to have you open something not needed.


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## cwsanfor (Aug 8, 2013)

Here's the strangest thing I've seen in about 50 years of hooking up electronics: the Denon POA-800s both work, just not with the Denon AVR-X4000. I connected them to some idle speakers with a known good receiver and CD player, woked fine. Connected them back to the AVR-X4000 using the same cables as with the working Onkyo 5130, no sounds. Tried duplexing the line level inputs, tried stereo and mono (moving the speaker wires accordingly), sacrificed a chicken, etc., no luck.

It's almost like they don't like the RCA cable I'm using on the AVR-X4000, or there's some impedance issue or something. The Onkyo (or the Sony) work fine, so it could be worse, and I can surely get my money out of them, but my heart was set on all-Denon amplification. I'll call Denon tomorrow, but I suspect I know how that will go.


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## JohnnieB (Jul 1, 2013)

Maby the sub outs' level needs to be raised higher. It could also be this.... in the level settings for speaker size, set them to "large". That could be why the sub out isn't producing a signal. Perhaps the mono amps need to see higher voltage/ input level


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## cwsanfor (Aug 8, 2013)

JohnnieB said:


> Maby the sub outs' level needs to be raised higher. It could also be this.... in the level settings for speaker size, set them to "large". That could be why the sub out isn't producing a signal. Perhaps the mono amps need to see higher voltage/ input level


John, they're not powering subs, just the Front Wide Pioneer Andrew Jones. Subs are working fine. They're powered SVS PB12s.


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## JohnnieB (Jul 1, 2013)

I totally misunderstood my friend. I will look into it further. Were you able to contact Denon? By the way.. nice set-up.


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## cwsanfor (Aug 8, 2013)

JohnnieB said:


> I totally misunderstood my friend. I will look into it further. Were you able to contact Denon? By the way.. nice set-up.


Thanks, Brother. No, they were closed today, I'll call them tomorrow, but am not optimistic, in that these amps are older than most of their TS agents. They are not likely to be too enthusiastic about going off-script about a what, 20-30 year-old amp. However, I plan to politely press the point and seek escalation (in the fashion that gets results from me when I'm doing TS), hoping they have one old codger (like me) who remembers this amp.

Again, this is not as serious as a Third World problem, the Onkyo works fine, and actually I can sell the POA-800s for a profit, I'm fairly sure. Still ....


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## JohnnieB (Jul 1, 2013)

I can understand why you are attempting this avenue. What a piece of art the x-4000 is! I enjoy a challenge so I'm going to do some research. The outcome should be well worth the effort.


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## cwsanfor (Aug 8, 2013)

JohnnieB said:


> I can understand why you are attempting this avenue. What a piece of art the x-4000 is! I enjoy a challenge so I'm going to do some research. The outcome should be well worth the effort.


Thanks, man. I've been googling it to no avail, but another set of eyes is appreciated. I suspect it has to do with impedance or some other quality of the RCA cables or the AVT-X4000 output or the POA-800 input, though it is weird that there would be a mismatch between to Denon components (if that is what the problem is). What I know is that I have hooked it up correctly and every way it can be hooked up.

I suppose my next step is to compare input/output characteristics of the two pieces of hardware, and try another RCA cable, although this one is known good, except perhaps for this one odd case.

Like I have time for this sort of thing, but now I've gotten curious. And yes, as you say, the AVR-X4000 is some pretty work. I have had the opposite of Buyer's Remorse: I find new stuff I like about it every day.


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## NBPk402 (Feb 21, 2012)

You had a Sony receiver hooked up to the FW out jacks on the Denon AVR, correct? I am assuming it had pre-outs and ins too and you had it hooked up to the pre in jacks on the Sony... Is that correct? Just trying to see if they were hooked up differently.


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## cwsanfor (Aug 8, 2013)

ellisr63 said:


> You had a Sony receiver hooked up to the FW out jacks on the Denon AVR, correct? I am assuming it had pre-outs and ins too and you had it hooked up to the pre in jacks on the Sony... Is that correct? Just trying to see if they were hooked up differently.


Yes, correct. I have not changed the connections on the AVR-X4000 end (a regular standard duplex RCA cable), and that configuration works with the Onkyo M-5130, which is a pure power amp, like the POA-800. It also worked with the Sony receiver. Same RCA cable, same speaker wires.

The only thing I can think of to try on the AVR-X4000 side is to use splitters to make a dual connection to one or both of the Denon POA-800s (depending on if I was trying them as mono or stereo, my desire is to use each as a mono amp), but I do not see anything in the Service Manual or online that suggests that should be necessary. All available literature indicates that you should be able to use a single RCA connection for signal (plugged into the POA-800 jack labelled "Mono"), and that in Mono mode, you wire the speaker wires to the top two jacks on the POA-800s (both red). I also tried using a single POA-800 set to Stereo, with both RCA connections going to the amp, and the four speaker wires in the normal position (lefts to lefts, rights to rights, reds to reds, whites to whites). I tried each POA-800 separately in Stereo, in case one was bad and one was good. I tried splitting the RCA connection at the POA-800 end so that both RCA inputs had something in them, not that it should matter, no luck.

However, like Sherlock Holmes said, once you eliminate the possible, you have to investigate the impossible. Or maybe I said that. I don't know.

Actually, the Onkyo sounds pretty good, but why did they put that long LED or whatever across the front? Looks like something from the Jetsons.


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## JohnnieB (Jul 1, 2013)

I wonder... would a simple hdmi to rca converter, out from the avr-x4000 to the poa-800. Seems like a waste because of the extra rca connections left unused but it may provide the signal needed. It could also be a waist of time and around 10 bucks. Just a shot in the dark.


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## NBPk402 (Feb 21, 2012)

cwsanfor said:


> Here's the strangest thing I've seen in about 50 years of hooking up electronics: the Denon POA-800s both work, just not with the Denon AVR-X4000. I connected them to some idle speakers with a known good receiver and CD player, woked fine. Connected them back to the AVR-X4000 using the same cables as with the working Onkyo 5130, no sounds. Tried duplexing the line level inputs, tried stereo and mono (moving the speaker wires accordingly), sacrificed a chicken, etc., no luck.
> 
> It's almost like they don't like the RCA cable I'm using on the AVR-X4000, or there's some impedance issue or something. The Onkyo (or the Sony) work fine, so it could be worse, and I can surely get my money out of them, but my heart was set on all-Denon amplification. I'll call Denon tomorrow, but I suspect I know how that will go.


Hot in the dark... Here is one more thing to try... Try hooking them up one more time in mono to the receiver that they worked with using the same cables. I am just wondering if something might have changed from when you tried it before, plus you tried them in stereo before when they worked , correct?


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