Pioneer VSX-LX505 AVR Review

[antcollinet]

Makes sense, I would say he told you the truth. That's the same for the 2020/21 D+M avrs. The amps remained powered (quiescent state) when not used.

I'm not sure quiescet is the right word if it is not possible to switch them off. They will still amplify the input voltage - and output that voltage at the speaker terminals. However, if there is no load connected there will be no current out of the speaker terminanls - so in that respect they are correct to say there will be very little current used.

Whether or not the protection still kicks in at that point depens on how it works. If it simply triggers at a certain (average?) output voltage for a certain time, (ie it assumes a typical speaker load is connected, and therefore output power is proportional to V^2), then the protection will still kick in even with no speakers connected. I would assume this is what it is doing, since Amir found it goes into protection even with the speakers not connected.

 

[peng]

I'm not sure quiescet is the right word if it is not possible to switch them off. They will still amplify the input voltage - and output that voltage at the speaker terminals. However, if there is no load connected there will be no current out of the speaker terminanls - so in that respect they are correct to say there will be very little current used.

Whether or not the protection still kicks in at that point depens on how it works. If it simply triggers at a certain (average?) output voltage for a certain time, (ie it assumes a typical speaker load is connected, and therefore output power is proportional to V^2), then the protection will still kick in even with no speakers connected. I would assume this is what it is doing, since Amir found it goes into protection even with the speakers not connected.

Right, I forgot the Onkyo's don't have preamp mode like the D+M avrs have and that would disconnect the power amp inputs. If the amps are not switched off, then it won't be in quiescent state either.

 

[ivo.f.doma]

I'm not sure quiescet is the right word if it is not possible to switch them off. They will still amplify the input voltage - and output that voltage at the speaker terminals. However, if there is no load connected there will be no current out of the speaker terminanls - so in that respect they are correct to say there will be very little current used.

Whether or not the protection still kicks in at that point depens on how it works. If it simply triggers at a certain (average?) output voltage for a certain time, (ie it assumes a typical speaker load is connected, and therefore output power is proportional to V^2), then the protection will still kick in even with no speakers connected. I would assume this is what it is doing, since Amir found it goes into protection even with the speakers not connected.

In that case, it is not even usable as a PRE PRO for LCR (even if SINAD will be good there), because after 30 seconds it starts limiting the other channels connected to the internal power amplifiers.
I GUESS NO!!!

 

[BJL]

I'm not sure quiescet is the right word if it is not possible to switch them off. They will still amplify the input voltage - and output that voltage at the speaker terminals. However, if there is no load connected there will be no current out of the speaker terminanls - so in that respect they are correct to say there will be very little current used.

Whether or not the protection still kicks in at that point depens on how it works. If it simply triggers at a certain (average?) output voltage for a certain time, (ie it assumes a typical speaker load is connected, and therefore output power is proportional to V^2), then the protection will still kick in even with no speakers connected. I would assume this is what it is doing, since Amir found it goes into protection even with the speakers not connected.

This doesn't make any sense. If the amplifiers are not drawing current, how are they amplifying anything? It strikes me as a logical impossibility that the signal from the pre-amps could be amplified with no load on the speaker terminals. If there are no speakers attached (or something else, like test equipment), then it is an open circuit. Onkyo told me specifically that if there is no load on the speaker terminals, the amplifiers are inactive and merely draw minimal current from the power supply.

In a review of an Emotiva power amp, Amir stated (correctly I am sure) "In use the A-500 never complained, shut down or go into thermal protection. This is nice benefit over the delicate amplifiers in AVRs which if you look at them wrong, they go into protection/shut down. Clearly this is much more robust solution."

I took the quoted comment as an article of faith, and it is consistent with my experience, consequently, other than for an experiment or convenience, I've always used external power amps. It seems like there is a lot of confusion and lack of clarity in the analysis in this thread. My only question has been whether this aggressive protection (or nanny circuit) has any impact on the pre-outs. Beyond that question, I don't care one bit about the internal amplifiers. My conclusion is that it does not affect the pre-outs (hope I'm right) so I'll just get on with enjoying the music.

 

[Doodski]

This doesn't make any sense. If the amplifiers are not drawing current, how are they amplifying anything? It strikes me as a logical impossibility that the signal from the pre-amps could be amplified with no load on the speaker terminals. If there are no speakers attached (or something else, like test equipment), then it is an open circuit. Onkyo told me specifically that if there is no load on the speaker terminals, the amplifiers are inactive and merely draw minimal current from the power supply.

The amplifier section is mainly comprised of the voltage gain stage and the current/unity gain stage. If voltage is applied to the input the amplifier will amplify the voltage and then right before the speakers the current gets amp'd up and that occurs whether speakers are connected or not. The operation of this circuity is not 100% efficient and there are losses.

 

[Rottmannash]

The amplifier section is mainly comprised of the voltage gain stage and the current/unity gain stage. If voltage is applied to the input the amplifier will amplify the voltage and then right before the speakers the current gets amp'd up and that occurs whether speakers are connected or not. The operation of this circuity is not 100% efficient and there are losses.

But will this negatively affect the signal from the pre outs if one is using outboard amps?

 

[Doodski]

will this negatively affect the signal from the pre outs if one is using outboard amps?

The pre-out should clip where it usually clips at and not be affected by the amp operation.

 

[peng]

But will this negatively affect the signal from the pre outs if one is using outboard amps?

Usually yes, pre out's distortions will increase quickly when the power amp output voltage clips, with or without speakers connected.

 

[antcollinet]

In that case, it is not even usable as a PRE PRO for LCR (even if SINAD will be good there), because after 30 seconds it starts limiting the other channels connected to the internal power amplifiers.
I GUESS NO!!!

Thats not what happens - in fact the pre outs might even be performing better as a result of the amp outputs being limited.

 

[antcollinet]

This doesn't make any sense. If the amplifiers are not drawing current, how are they amplifying anything?

Vout = Vin * gain. That is voltage amplification.

 

[amirm]

Can a power amp really go into protection mode without a load connected?

Some do in my testing, and some don't. The Yamaha RX-A3080 is an example of one that did: https://www.audiosciencereview.com/forum/index.php?threads/yamaha-rx-a3080-review-avr.29520/

Yamaha RX-A3080 Measurements
As usual, I started to measure the DAC portion by using the pre-amp output, only to be punched in the face by the AVR going into protection mode. As far as I can tell, there is no way to shut off the amps so not only do they disturb the analog outputs, but also don't let you crank it up to full volume beyond what the internal amps can handle. What were they thinking?

 

[dlaloum]

In that case, it is not even usable as a PRE PRO for LCR (even if SINAD will be good there), because after 30 seconds it starts limiting the other channels connected to the internal power amplifiers.
I GUESS NO!!!

The issues I experienced with the sound from the power amp output, were not present when running as Pre into my external amps.

Of course I have no evidence that the issues were related to the Nanny State being triggered - and my suspicion is that the amps couldn't drive the low impedance load presented by my speakers - and that the nanny state/protection power down, was never triggered.

But as stated before - no one out there is reporting this issue in actual use... and my personal use as a prepro is not showing this issue either.

Further in depth measurement, reverse engineering, and analysis would be required to determine what exactly is happening and what the parameters around it are....

Right now these AVR's are subjectively excellent, with the exception being low impedance speakers, and used as prepro's driving external amps they are showing excellent performance.

There is a strong cognitive dissonance between the experience of Pioneer/Onkyo/Integra owners, and some of the assumed ramifications of AmirM's measurements.... I say assumed ramifications, because right now, we don't know what the actual ramifications are outside the limits of the specific tests amirm has done... a lot of the rest is a bunch of speculation.

 

[damirj79]

So the current situation preditcs next logical step would be to find out not only if but also find exact conditions when and how the protection kicks. As it stands rigjt now, there is just a buch of guessing. At the end, @amirm isconly a human, allowing him to make mistakes. Intentional or not. I am hapoy owner of lx305 model, it did not happen yet for me to see the limiter would engage. And I have impedance demading speakers also, dropping below 2ohms. Maybe @amirm used EU version for 220V in USA? I am sure he did not, but who knows...

 

[welder911]

Hello, I'm using a vsx 930 too, is there such a restriction in my amp? @amirm

 

[amirm]

So the current situation preditcs next logical step would be to find out not only if but also find exact conditions when and how the protection kicks. As it stands rigjt now, there is just a buch of guessing. At the end, @amirm isconly a human, allowing him to make mistakes. Intentional or not. I am hapoy owner of lx305 model, it did not happen yet for me to see the limiter would engage. And I have impedance demading speakers also, dropping below 2ohms. Maybe @amirm used EU version for 220V in USA? I am sure he did not, but who knows...

I know. I measured the thing. And no, it doesn't turn on if it is set for the wrong voltage. Why would an EU model land here anyway?

In reverse, you don't know if you have or have not hit the issue. There is no indicator. Even if you want to defend this "feature," you need to contact the company and complain about it taking such drastic action on performance without letting the owner know. That is what I did. Sadly they ignored my message but if more people do this, maybe things will improve in the future.

 

[damirj79]

The indicator is in the web GUI menu, so this is kind of clear situation. And you are probably reading it wrong, as I am not defending the situation as is, for me at least, just a prove that price cuts are reflecting in worse user experience instead of going for better and it is happening just all around us. For me it is still more a question of finding a perfect AVR (amplifier, speakers, etc replace with your own object) and even if a such thing would exists, it will probably not meet other factors, like most obviously price, then maybe design, size etc.. with size being the most notable factor for me thinking of such an advances in electronics and computers and we still have huge ugly boxes..

 

[DavidMcRoy]

In that case, it is not even usable as a PRE PRO for LCR (even if SINAD will be good there), because after 30 seconds it starts limiting the other channels connected to the internal power amplifiers.
I GUESS NO!!!

To reiterate what I wrote waaay up the thread, I only use my "similar" VSX-LX503 as a processor and it has only ever gone into Nanny Mode when passing pink noise or sine waves through any or all channel(s). It's never done that on program audio signals. I suspect there may be a circuit involved that is able to detect the presence of steady-state signals, and if such are detected, the countdown starts. I always hear a telltale series of relay clicks when auto-shutdown is imminent.

 

[Aerith Gainsborough]

As we see, it pulls back around the same time. This time the AVR was running pretty cool indicating this limiting is time based, no environment. You only have your maximum power for 35 seconds after which, power is limited until you power cycle the unit!

²

Buying AVRs really seems to be a friggin minefield, when it doesn't have to be.

I'll definitely steer clear of that brand, should I ever need to replace my lil' Yammy.

 

[peng]

Thats not what happens - in fact the pre outs might even be performing better as a result of the amp outputs being limited.

Yeah, it really depends on how the power amp output's limiting scheme is designed/work, may be someone can find out from Onkyo.

 

[peng]

The issues I experienced with the sound from the power amp output, were not present when running as Pre into my external amps.

Of course I have no evidence that the issues were related to the Nanny State being triggered - and my suspicion is that the amps couldn't drive the low impedance load presented by my speakers - and that the nanny state/protection power down, was never triggered.

But as stated before - no one out there is reporting this issue in actual use... and my personal use as a prepro is not showing this issue either.

Further in depth measurement, reverse engineering, and analysis would be required to determine what exactly is happening and what the parameters around it are....

Right now these AVR's are subjectively excellent, with the exception being low impedance speakers, and used as prepro's driving external amps they are showing excellent performance.

There is a strong cognitive dissonance between the experience of Pioneer/Onkyo/Integra owners, and some of the assumed ramifications of AmirM's measurements.... I say assumed ramifications, because right now, we don't know what the actual ramifications are outside the limits of the specific tests amirm has done... a lot of the rest is a bunch of speculation.

That makes sense to me. Since you mentioned "..a bunch of speculation..", I would say that one good thing about such test results is that because of such tests, we don't have to speculate as much. As you pointed out, a lot of the owners are not experiencing the "ramifications", and that's not surprising because it could simply be that in their usage, the "pull back" behavior Amir found, might not have been triggered, or triggered but not noticed by the owner (as Amir found, there was no indicators). Just like your specific speakers did not do well with your Integra and you noticed it, yet other owners may not (unless the unit actually shutdown).

Having seen the test results, potential owners can make a more informed decision. For example, if I had the kind of uncommon impedance/phase angle characteristics speakers like yours, the RZ50, and its Pioneer, Integra cousins would not be my choice. Since I don't have such speakers and have no plan to acquire anything like them, the RZ50 would be on my short list if I needed an AVR.

In my opinion, ASR is a good place for people who prefer objective measurements to help them make their choices. Those who don't like the results and/or questioned their values would still benefit from the information, that again, should help them in making more informed decisions such as to avoid the DUT (the LX505 in this case), or not, based on their needs.