Pioneer VSX-LX505 Power Remeasurement

[EWL5]

We don't know this to be the case - no one has actually checked when it was confirmed to be in "limp mode" - whether the status screen "protection" flag is set or not. (and for obvious reasons this can only be done in a lab where the instrumentation is available to test and confirm)

Both you, and I are making assumptions.... and we may well be wrong.

As far as I'm concerned, the evidence is pretty clear for a "limp mode" despite the lack of obvious indication (by the manufacturer):
1) Amir's reviews of the 7100, RZ50, and 505 all show the same degradation at 4 ohms to 35W into 2ch that is not resolved until the unit is unplugged and plugged back in.
2) Yours, @vitola231, and others in forums who have experienced sound degradation specifically into low impedance speakers. I haven't heard any complaints from nominal 8 ohm speaker owners.
3) The lack of a limp mode from Denon 3800 and higher. Your good experience running on internal amps alone in the 4800 after struggling with the DRX 3.4 should have been proof of that but you still deny that Amir's 4 ohm tests somehow don't translate to real-world performance?!!!

I've used the scientific method to come to my conclusions. If the above is not compelling enough, I wish I had asked @amirm to test the 4 ohm mode on purpose to see what the resulting wattage would be when he had the recent 505. My guess is it would have been 35W into 2ch! Missed opportunity!

 

[peng]

As far as I'm concerned, the evidence is pretty clear for a "limp mode" despite the lack of obvious indication (by the manufacturer):
1) Amir's reviews of the 7100, RZ50, and 505 all show the same degradation at 4 ohms to 35W into 2ch that is not resolved until the unit is unplugged and plugged back in.
2) Yours, @vitola231, and others in forums who have experienced sound degradation specifically into low impedance speakers. I haven't heard any complaints from nominal 8 ohm speaker owners.
3) The lack of a limp mode from Denon 3800 and higher. Your good experience running on internal amps alone in the 4800 after struggling with the DRX 3.4 should have been proof of that but you still deny that Amir's 4 ohm tests somehow don't translate to real-world performance?!!!

I've used the scientific method to come to my conclusions. If the above is not compelling enough, I wish I had asked @amirm to test the 4 ohm mode on purpose to see what the resulting wattage would be when he had the recent 505. My guess is it would have been 35W into 2ch! Missed opportunity!

Audiophiles (using the term loosely as I don't know who they really are, may be I am one too lol) are so easily fooled, so it is possible that few users realized their unit was limping, to clearly identify such experience, I think the user would have to sit down and come up with a plan to test it out before using their unit to listen to their favorite music that they are familiar with, rather use use it as usual. Not picking on Marantz fans who believe in marketing info, some of the low profile series users would think they were hearing the "Marantz" sound, because of the story told by Marantz marketing (remember before they also pin pointed the DAC reconstruction filter being the reason only since about 2 years ago, prior to that it was always the HDAM..), without realizing the low profile series don't have HDAMs at all.

Another example, but we would have to assume it was a true story..

3e audio A7/A7 Mono Amplifier Review

I said the ZA3 plays louder, I didn't say I preferred it because it played louder. I prefer it because I find it sharper in the mid and high range and that is a nice fit with my speaker, and I find the A7 is more rolled-off, more layback, with a less pronounced soundstage. The a7 has more body...

www.audiosciencereview.com

It may sound irrelevant to the topic being discussed here, but in a way it is relevant, that this "hearing xyz differences for different reasons including the effects or being in limp mode, or not.., is a real mess!

A probably apocryphal test years ago describes a room full of scientific audiophiles who were told they would be comparing the sound of a system swapping out standard and audiophile power cables. Unsurprisingly none of the listeners heard a difference. The story goes that what was actually being switched was speaker polarity, an easily audible change. The scientific types were blinded by their scientific bias to real audible differences.

 

[JSmith]

their unit was limping

... and no one wants that.


JSmith

 

[dlaloum]

As far as I'm concerned, the evidence is pretty clear for a "limp mode" despite the lack of obvious indication (by the manufacturer):
1) Amir's reviews of the 7100, RZ50, and 505 all show the same degradation at 4 ohms to 35W into 2ch that is not resolved until the unit is unplugged and plugged back in.
2) Yours, @vitola231, and others in forums who have experienced sound degradation specifically into low impedance speakers. I haven't heard any complaints from nominal 8 ohm speaker owners.
3) The lack of a limp mode from Denon 3800 and higher. Your good experience running on internal amps alone in the 4800 after struggling with the DRX 3.4 should have been proof of that but you still deny that Amir's 4 ohm tests somehow don't translate to real-world performance?!!!

I've used the scientific method to come to my conclusions. If the above is not compelling enough, I wish I had asked @amirm to test the 4 ohm mode on purpose to see what the resulting wattage would be when he had the recent 505. My guess is it would have been 35W into 2ch! Missed opportunity!

Yes I agree - there is a "Limp mode" demonstrably as measure on the lab bench test.
There is also a shutdown protective mode (where the AVR completely shuts itself down)
Finally there is also a mode that triggers the "protection" flag on the status screen - which cannot be the shutdown protective mode (as the flag would be redundant in that case) - but may in fact be the "limp mode" - we have no confirmation of this in the positive or negative as no one who has bench tested the units involved has monitored the status flag.

My working assumption (based on my experiences with my Integra DRX3.4) is:
1) The status screen "protection" flag refers to the "limp mode" (as nothing else makes logical, deductive, sense)
2) Listening tests of the 3.4 immediately after full power up, showed it subjectively not sounding great into my Gallo speakers... in the first 30s after power up and starting to listen, prior to any likelihood of "limp mode" activation.
3) Brief listening at 4ohm showed no difference to listening at 6ohm (a test based on an assumption that limp mode=4ohm mode... an assumption that I have not made, but still...)
4) Listening to the 3.4 driving my B&O Penta's (a relatively benign 8ohm load) showed no differences between power up fresh, 4ohm mode, or 6ohm/8ohm mode.

The symptoms appear to be consistent with amplifier instability into a reactive load, rather than power limitations driven by either limp mode or 4 ohm mode. - The subjective symptoms were primarily in the midrange and higher frequencies, not in the more power & current demanding lower frequencies driving the woofer.

Actual measurements in my room show that continuous power consumption is typically around 1W (so does not typically approach the lab test limp mode level... ) with peaks never exceeding 16W - that means that even at the "limp mode" measured capacity, the amps should not be constrained in my situation.... (ie: there should be no audible difference) - and yet there is.

Sensitivity / power use of the B&O Penta's vs the Gallo Ref3.2 are well nigh identical.... yet the former sounds fine, the latter does not. (another indication that power limitations imposed by "limp mode" or 4 ohm mode, are highly unlikely to be a factor)

I continue to maintain that the only thing that is consistent with all of the above is amplifier instability into a reactive load, causing substantive rise in distortion...

I have 2 different external power amps, both known to be stable into reactive loads as low as 1 ohm - neither exhibited the symptoms.
What I do not have available (and if I had it, I would have disposed of it!!) - is any other amps that are unstable into a reactive load.

Yes I can state that the Denon X4800 appears to be stable into the reactive load (big tick for the Denon)...

 

[EWL5]

Yes I agree - there is a "Limp mode" demonstrably as measure on the lab bench test.
There is also a shutdown protective mode (where the AVR completely shuts itself down)
Finally there is also a mode that triggers the "protection" flag on the status screen - which cannot be the shutdown protective mode (as the flag would be redundant in that case) - but may in fact be the "limp mode" - we have no confirmation of this in the positive or negative as no one who has bench tested the units involved has monitored the status flag.

My working assumption (based on my experiences with my Integra DRX3.4) is:
1) The status screen "protection" flag refers to the "limp mode" (as nothing else makes logical, deductive, sense)
2) Listening tests of the 3.4 immediately after full power up, showed it subjectively not sounding great into my Gallo speakers... in the first 30s after power up and starting to listen, prior to any likelihood of "limp mode" activation.
3) Brief listening at 4ohm showed no difference to listening at 6ohm (a test based on an assumption that limp mode=4ohm mode... an assumption that I have not made, but still...)
4) Listening to the 3.4 driving my B&O Penta's (a relatively benign 8ohm load) showed no differences between power up fresh, 4ohm mode, or 6ohm/8ohm mode.

The symptoms appear to be consistent with amplifier instability into a reactive load, rather than power limitations driven by either limp mode or 4 ohm mode. - The subjective symptoms were primarily in the midrange and higher frequencies, not in the more power & current demanding lower frequencies driving the woofer.

Actual measurements in my room show that continuous power consumption is typically around 1W (so does not typically approach the lab test limp mode level... ) with peaks never exceeding 16W - that means that even at the "limp mode" measured capacity, the amps should not be constrained in my situation.... (ie: there should be no audible difference) - and yet there is.

Sensitivity / power use of the B&O Penta's vs the Gallo Ref3.2 are well nigh identical.... yet the former sounds fine, the latter does not. (another indication that power limitations imposed by "limp mode" or 4 ohm mode, are highly unlikely to be a factor)

I continue to maintain that the only thing that is consistent with all of the above is amplifier instability into a reactive load, causing substantive rise in distortion...

I have 2 different external power amps, both known to be stable into reactive loads as low as 1 ohm - neither exhibited the symptoms.
What I do not have available (and if I had it, I would have disposed of it!!) - is any other amps that are unstable into a reactive load.

Yes I can state that the Denon X4800 appears to be stable into the reactive load (big tick for the Denon)...

By your own admission to peng, you never unplugged and re-plugged the AVR. That is known to reset the “limp mode”. It’s also documented by some owners in my unpopular AVS thread.

 

[dlaloum]

By your own admission to peng, you never unplugged and re-plugged the AVR. That is known to reset the “limp mode”. It’s also documented by some owners in my unpopular AVS thread.

Actually I pointed out that my initial listening tests on first plugging in the device, showed the same issues in midrange/imaging... which is exactly that - plugging it into power. And is a subjective test indicating that the issue exists independently of the "limp mode".

 

[amirm]

Finally there is also a mode that triggers the "protection" flag on the status screen - which cannot be the shutdown protective mode (as the flag would be redundant in that case)

Why? Shouldn't the web UI show the status of the machine remotely? And have you seen that light up in Web UI while the amp was playing audio?

 

[peng]

I continue to maintain that the only thing that is consistent with all of the above is amplifier instability into a reactive load, causing substantive rise in distortion...

Your are on this interesting topic again, that seems like a forever discussion, but heck, I am a curious person so I don't mind participating hoping that one day we might get to the truth one way or another.

Meanwhile, I would suggest you be open to other possibilities instead of maintaining there's only "one thing..". As an example (surely there could be others), it could still be something/the way the specific protection schemes used in those Onkyo/Integra/Pioneer models work that resulted in the way they behaved with your specific poorly designed (based on their impedance/phase angle characteristics, note: TLSGuy on Audioholics would say such a thing for sure lol) speaker model, and it could well be like you said instability, but instability resulted not necessarily because of the speaker load alone, but when the protective scheme reacting to it.

We are not dealing with the typical kind of protection that would just trip the unit, or lowering the rail voltage, but in this case it activate the kind of "limp" mode as Amir observed/described. To say the amp not being stable into a reactive load is a generalized statement that certainly is not true in practical sense, as almost all electromagnetic speakers are reactive loads, yet even your specific AVR only had issue with your particular Gallo model speaker.

 

[EWL5]

Actually I pointed out that my initial listening tests on first plugging in the device, showed the same issues in midrange/imaging... which is exactly that - plugging it into power. And is a subjective test indicating that the issue exists independently of the "limp mode".

Based on your posts here and over at AVS, I do consider you to be a thoughtful and detailed oriented person. This is why it's all the more frustrating that what is "obvious" for me needs to be pointed out (sorry, just disappointed in your comments and no judgment of your character). Yes, there is no doubt that the "limp mode" presents itself upon first plug in. This is not in doubt, as pointed out in Amir's original review of the 505:

"At this point I ran my 8 ohm power sweep and was stomped to see that there was so little power available (red lines):"
"The unit is rated at 120 watts and I was just getting 20 watts! No amount of reading the manual and searching showed any kind of "eco mode" that would limit power. After trying many things I remembered the same issue in other Pioneer AVRs such as VSX-LX303. That AVR would limit its output power after 30 seconds or so:"
"I repeated the same test, picking 44 watts of output and monitoring the amount of distortion. If the amp pulled back, that would be in clipping region and hence distortion would shoot way up just as above. And that is what it did:"
"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!"

Notice in the pic how a power cycle was necessary to get something reasonable for the 4 ohm test. As we know, plugging in the 2nd time gets you something but only lasts for seconds! I don't believe you ever attempted a 2nd plug in specifically to do critical listening.

Please do yourself a favor and reread Amir's reviews of the 505, 7100, and RZ50. They all exhibit this "limp mode" and the behaviors are consistent with what's being said by you and others who inevitably moved on to other brands. We are all interested in "truth in engineering" and that's why we post to ASR. If we didn't care, then AVS and other similar forums would suffice!

If you object to the use of "limp mode", I don't mind changing it to "involuntary 4-ohm mode" but it has yet to be proven, especially if an RZ30 ever comes across Amir's hands...

 

[dlaloum]

Why? Shouldn't the web UI show the status of the machine remotely? And have you seen that light up in Web UI while the amp was playing audio?

No, I have never seen the protection flag set when the amp was playing Audio.

And if we have a full protection shutdown (where the AVR shuts down the power to self protect, not "limp mode") - then as there is no power to the processing & networking chips, there would be no way of it responding on the web interface - it would be completely offline.

 

[dlaloum]

Your are on this interesting topic again, that seems like a forever discussion, but heck, I am a curious person so I don't mind participating hoping that one day we might get to the truth one way or another.

Meanwhile, I would suggest you be open to other possibilities instead of maintaining there's only "one thing..". As an example (surely there could be others), it could still be something/the way the specific protection schemes used in those Onkyo/Integra/Pioneer models work that resulted in the way they behaved with your specific poorly designed (based on their impedance/phase angle characteristics, note: TLSGuy on Audioholics would say such a thing for sure lol) speaker model, and it could well be like you said instability, but instability resulted not necessarily because of the speaker load alone, but when the protective scheme reacting to it.

We are not dealing with the typical kind of protection that would just trip the unit, or lowering the rail voltage, but in this case it activate the kind of "limp" mode as Amir observed/described. To say the amp not being stable into a reactive load is a generalized statement that certainly is not true in practical sense, as almost all electromagnetic speakers are reactive loads, yet even your specific AVR only had issue with your particular Gallo model speaker.

I agree - and I can only base my personal conclusions on deductive reasoning....

Just glad I don't have that issue with the Denon X4800...

 

[amirm]

And if we have a full protection shutdown (where the AVR shuts down the power to self protect, not "limp mode") - then as there is no power to the processing & networking chips, there would be no way of it responding on the web interface - it would be completely offline.

It depends on how that is implemented. Protection circuits usually disconnect the output from the speaker connection. Some do turn it off completely. Others seem to shut down fair drastically but could still allow networking subsystem and display to function.

 

[peng]

It depends on how that is implemented. Protection circuits usually disconnect the output from the speaker connection. Some do turn it off completely. Others seem to shut down fair drastically but could still allow networking subsystem and display to function.

Right, for example, in the case of Denon and Marantz, in the last few years every time someone posted questions related to their units going on protection mode, there were indications of whether the unit tripped on overcurrent, thermal, or ASO (DC, or Short cct) when the units did shut down without tipping.

 

[peng]

I agree - and I can only base my personal conclusions on deductive reasoning....

Just glad I don't have that issue with the Denon X4800...

Your use case does confirm one thing, those Denon, and I would safely assume Marantz as well, AVRs are well designed for difficult loads such as the rather unique Gallo speaker that clearly exhibit extremely case of impedance dip(s), tough phase angles, and likely tweeter that is not just highly reactive, but capacitively reactive, enough to cause less well designed amps to become unstable.

It is still quite possible that your previous AVR made it worse because of it's specific protection scheme (the limp mode related one) that might have been a little too aggressive, and since you didn't listen now and/or push the amp that hard, as you mentioned before, the avr amp probably was on the margin case of sensing the V/I sensing and get itself in trouble, instead of shutting down or just limping, it actually started to "chatter", sort of doing its V/I limiting off and on, so in your use case it really isn't so much about high current capability for one of two low impedance dips, but as you alluding to before, more about stability related issues.

It's all speculation on my part, who knows, or who cares, best to avoid using AVR amps to deal with known difficult to drive speakers let alone using marginal AVR amps with aggressive protection schemes.

 

[EWL5]

Your use case does confirm one thing, those Denon, and I would safely assume Marantz as well, AVRs are well designed for difficult loads such as the rather unique Gallo speaker that clearly exhibit extremely case of impedance dip(s), tough phase angles, and likely tweeter that is not just highly reactive, but capacitively reactive, enough to cause less well designed amps to become unstable.

It is still quite possible that your previous AVR made it worse because of it's specific protection scheme (the limp mode related one) that might have been a little too aggressive, and since you didn't listen now and/or push the amp that hard, as you mentioned before, the avr amp probably was on the margin case of sensing the V/I sensing and get itself in trouble, instead of shutting down or just limping, it actually started to "chatter", sort of doing its V/I limiting off and on, so in your use case it really isn't so much about high current capability for one of two low impedance dips, but as you alluding to before, more about stability related issues.

It's all speculation on my part, who knows, or who cares, best to avoid using AVR amps to deal with known difficult to drive speakers let alone using marginal AVR amps with aggressive protection schemes.

There has always been talk about why D&M units are so much more expensive compared to the equivalent PAC units. I think we are starting to understand why...

It's funny because I am using my first ever Denon and I'm being called a "Denon shill". Apparently my years of multiple Pioneer Elite ownership (not to mention my first ever AVR was an Onkyo) doesn't count for anything. LOL!

 

[dlaloum]

Your use case does confirm one thing, those Denon, and I would safely assume Marantz as well, AVRs are well designed for difficult loads such as the rather unique Gallo speaker that clearly exhibit extremely case of impedance dip(s), tough phase angles, and likely tweeter that is not just highly reactive, but capacitively reactive, enough to cause less well designed amps to become unstable.

It is still quite possible that your previous AVR made it worse because of it's specific protection scheme (the limp mode related one) that might have been a little too aggressive, and since you didn't listen now and/or push the amp that hard, as you mentioned before, the avr amp probably was on the margin case of sensing the V/I sensing and get itself in trouble, instead of shutting down or just limping, it actually started to "chatter", sort of doing its V/I limiting off and on, so in your use case it really isn't so much about high current capability for one of two low impedance dips, but as you alluding to before, more about stability related issues.

It's all speculation on my part, who knows, or who cares, best to avoid using AVR amps to deal with known difficult to drive speakers let alone using marginal AVR amps with aggressive protection schemes.

It is worth pointing out, that the PAC AVR's for all their power amp nanny circuit flaws, do make excellent AVP's - and in my use, an excellent hybrid AVR, I fitted a power amp to run the mains, and ran surrounds and heights from the AVR...

At under US$1000 that is a bargain just as an AVP, and the additional channels of amplification for height and surround can be considered a freebie bonus!

I never really expected an economy AVR like the Integra DRX3.4 (or Onkyo RZ30) to have the power/current/stability to run my mains.

When moving to the Denon's (primarily in my search for a Dirac ART capable processor) - I opted to go up a notch from the X3800 to the X4800 just to increase the likelihood that it would in fact handle my mains... but my initial assumption going in was that it wouldn't - I was pleasantly surprised when it did handle them well!! (I am planning further testing "when I get a round tuit" to further compare internal amps to external power amps on the Denon...)

 

[dlaloum]

There has always been talk about why D&M units are so much more expensive compared to the equivalent PAC units. I think we are starting to understand why...

It's funny because I am using my first ever Denon and I'm being called a "Denon shill". Apparently my years of multiple Pioneer Elite ownership (not to mention my first ever AVR was an Onkyo) doesn't count for anything. LOL!

Accusers in that style, are frequently projecting their own attitudes!

 

[Power Pop 23]

It is worth pointing out, that the PAC AVR's for all their power amp nanny circuit flaws, do make excellent AVP's - and in my use, an excellent hybrid AVR, I fitted a power amp to run the mains, and ran surrounds and heights from the AVR...

At under US$1000 that is a bargain just as an AVP, and the additional channels of amplification for height and surround can be considered a freebie bonus!

Agreed,

As a $749 'AVP' in my 4.1 configuration, the 'freebie bonus' for this Pioneer '505' is the inclusion of a paid Dirac Live license.

 

[cbrworm]

I don't know if they are similar, but I worked on an old Onkyo TX-SR805 AV Receiver that had 3 sets of rail voltages. High voltage was if it was set to 6+ ohms and temperature/current were good. Med voltage was if it was set to 4 ohms and temperature/current were good. If the temp got too hot in high voltage, it would drop to med, then ultimately low voltage if the temp didn't go down. If current was too high in High voltage mode, it would drop directly to Low. If there was a direct short on the outputs, the unit would go into protect mode.

It would be interesting to test one of these 'modern' Pioneer/Onkyos with a music source and reasonable load. It's been a defect for too long for it to have been an oversight.

 

[Miker 1102]

There has always been talk about why D&M units are so much more expensive compared to the equivalent PAC units. I think we are starting to understand why...

It's funny because I am using my first ever Denon and I'm being called a "Denon shill". Apparently my years of multiple Pioneer Elite ownership (not to mention my first ever AVR was an Onkyo) doesn't count for anything.

... and no one wants that.


JSmith

I laughed at the last comment.
I really did shop for avrs and test most of the major commercial lines..including an integra, the 503, and an rz70 that sat in the box. My thought was if you were new to home theater the Onkyo/Pioneer products would be hard to pass up. But once you try a mid level Denon product you cannot really go back. I am not putting an avr like the rz line down. Its just that the Denon line is simply designed better. I remember using the 503 and thinking it did not make sense that you could not adjust the crossovers individually. You had to chose between 80, 100, 120 etc. I did not experience the limp mode but as somebody pointed out the average user would have to pay attention. I think user education is vital for people who want to get the best use out of thier avrs. The more educated I became, the more spending the extra money on the Denon made sense.