Yamaha RX-v685 Sub Out not working

[The Dali]

Hi everyone... just wanted to calidate that I am not ctrazy...

I have a v685 that has been working fine for a few years. I recently noticed that the sub wasn't working so I started fooling around trying to determine what could be the issue. My belief is that it is human error, but I've tried everything I can think of and now I'm feeling like it is probably a broken sub-out. Before I go there... I would love your input!

So far I've tried:
- switched cables
- tried a second sub to ensure the first one is working
- ensured the system has SUB ON
- turned up the sub volume on the unit
- did the TEST TONES on the unit and it plays tones for all speakers except the sub
- updated the firmware on the unit
- re-set the unit to factory specs

Nothing worked... any other options or anything I forgot?

 

[everettT]

Hi everyone... just wanted to calidate that I am not ctrazy...

I have a v685 that has been working fine for a few years. I recently noticed that the sub wasn't working so I started fooling around trying to determine what could be the issue. My belief is that it is human error, but I've tried everything I can think of and now I'm feeling like it is probably a broken sub-out. Before I go there... I would love your input!

So far I've tried:
- switched cables
- tried a second sub to ensure the first one is working
- ensured the system has SUB ON
- turned up the sub volume on the unit
- did the TEST TONES on the unit and it plays tones for all speakers except the sub
- updated the firmware on the unit
- re-set the unit to factory specs

Nothing worked... any other options or anything I forgot?

Are your speakers set to small?

 

[The Dali]

I just checked and yes set to small.

 

[TLS Guy]

I just checked and yes set to small.

So, I assume you did a hard reset. You might want to do another hard reset. Also connect a known signal to the sub, to make sure it really is working. If all that fails, it looks like new receiver time.

 

[The Dali]

Thx. Yes, I tested the Sub on another system and was working fine. And I tested the system in question with a known working sub. I will do another reset.

 

[TLS Guy]

Thx. Yes, I tested the Sub on another system and was working fine. And I tested the system in question with a known working sub. I will do another reset.

If that reset does not work, there is a workaround, if your sub has right and left inputs. You could set your receiver to sub none right and left speakers large and connect the right and left preouts to the right and left sub inputs and use the sub speaker volume and crossover.

If the reset fails, then I suspect the IC op amp chip to the subouts has failed.

 

[The Dali]

Hi, nothing worked with the reset, but your comments about the pre-outs got me thinking... and yes my sub has the speaker line inputs so what you are saying is I could just connect the sub to the amplifier with speaker wire to each input and it would process the signal that way. I did some research and looks like I would need to hook up the mains and the sub to the same outputs from the amplifier. That could be a way around this, although would that work correctly when decoding movie content (vs stereo music)?

 

[TLS Guy]

Hi, nothing worked with the reset, but your comments about the pre-outs got me thinking... and yes my sub has the speaker line inputs so what you are saying is I could just connect the sub to the amplifier with speaker wire to each input and it would process the signal that way. I did some research and looks like I would need to hook up the mains and the sub to the same outputs from the amplifier. That could be a way around this, although would that work correctly when decoding movie content (vs stereo music)?

That is not what I said. From pictures I have seen, your receiver has right and left high impedance preouts at line level.

So you need two RCA cables. You connect one end to the right and left preputs and the other ends to the right and left RCA inputs on your sub.

Then you set your receiver to sub no, and left and right speakers large. That will be very close to current performance as long as your mains are able to tolerate being set to large.

I would contact your Yamaha service center and get an estimate for repair. At the age of your receiver I doubt repair is a realistic option, but it may be. My plan will likely get you by until you can get another receiver.

 

[The Dali]

Gotcha - I actually tried both ways. They both worked about the same. I have it set up with the RCAs using the pre-outs for now.

But, for movies it seems like a short-term fix so I'll start looking at AVR options.

Thank you!

 

[TLS Guy]

Gotcha - I actually tried both ways. They both worked about the same. I have it set up with the RCAs using the pre-outs for now.

But, for movies it seems like a short-term fix so I'll start looking at AVR options.

Thank you!

I find others have had this problem you are experiencing. One poster was able to "wake up" the sub out by turning up the sub output to +10db.

 

[The Dali]

Thanks for your help. I've been using the AVR and bass is working great (using pre-outs). I'm going to roll with it for a while.

 

[infoisthub]

Hi everyone... just wanted to calidate that I am not ctrazy...

I have a v685 that has been working fine for a few years. I recently noticed that the sub wasn't working so I started fooling around trying to determine what could be the issue. My belief is that it is human error, but I've tried everything I can think of and now I'm feeling like it is probably a broken sub-out. Before I go there... I would love your input!

So far I've tried:
- switched cables
- tried a second sub to ensure the first one is working
- ensured the system has SUB ON read more
- turned up the sub volume on the unit
- did the TEST TONES on the unit and it plays tones for all speakers except the sub
- updated the firmware on the unit
- re-set the unit to factory specs

Nothing worked... any other options or anything I forgot?

Check if the subwoofer is set to ON, the crossover frequency is appropriate (e.g., 80Hz), and speaker size is set to small to route bass to the sub. If test tones still don’t work, try connecting the sub to a different device (like a phone via RCA) to confirm it’s operational. If the sub works but not with the receiver, the sub-out on the RX-V685 may be faulty and likely needs repair.

 

[The Dali]

Thx. Yeah it appears the sub out is defective, which is kinda strange “out of the blue” … so I’m looking for replacement now.

 

[TLS Guy]

Thx. Yeah it appears the sub out is defective, which is kinda strange “out of the blue” … so I’m looking for replacement now.

You are far from the first to have this problem. I would open the case to make sure the female RCA plug is not somehow disconnected from the board.

I think the reason we run into this problem with sub outs is because of that darned LFE channel. The LFE channel goes to 120 Hz with a 10 db boost. Every 3 db doubles voltage.

The crossover works from ICs, and are first order crossover in series to make the fourth order. They are all in one chip. However I'm sure the voltage gets quite high which leads to IC failure in the sub outs.

I think the film industry is gratuitous with the LFE sound effects. I find them very overdone and annoying often. I don't even use sub drivers in the Av room, but when the grandchildren are watching a movie these gratuitous effects can rattle the furniture and pictures on the walls downstairs. I suppose this is all done to sell subs. I don't need that to prove my bass works, a decent pipe organ can do that even better.

 

[Teetertotter?]

For replacement AVR, you might think DENON, IMO. Gooid luck