Pioneer VSX-LX505 AVR Review

[peng]

Quite....

However my analysis of AVR's and Prepros around this price level, did not indicate any that would provide confidence with their ability to handle my speakers - ultimately all contenders were suspect in terms of very low impedance handling.... so then it became an issue of their suitability to run surround/height channels, and effectiveness as pre-amps / processors. (ie: after my initial analysis, I was fairly sure that I would need to use my power amps regardless which AVR I went with... unless I was willing to go up to a much higher price category - and even then...)

Shortlist ended up with Anthem, Denon and Onkyo/Integra.... I wanted to move away from Audyssey.... and then decided I preferred to try out Dirac based on the many positive reviews I was reading (and a couple of impressive listening sessions at audio shows a few years back).

So, not overly concerned about the power amp weaknesses - and the processing and sound quality strengths are excellent.

Of course, the test results show for use as prepro that is fine but for use as avr, it depends, and one will have examine the results carefully and then decide if it can meet one's requirement.

 

[JSmith]

The indicator is in the web GUI menu, so this is kind of clear situation.

The indicator is for protection mode... this is power limiting we're talking about. The amp doesn't shut off... it continues in a lower max power state until restarted.

JSmith

 

[DavidMcRoy]

The indicator is for protection mode... this is power limiting we're talking about. The amp doesn't shut off... it continues in a lower max power state until restarted.

JSmith

That's an important distinction. In the case of a "similar" VSX-LX503 being used as a processor only, the entire unit shuts down after some period of time with steady-state signals such as pink noise or sine waves feeding the input or inputs, such as during "manual" room correction tests. I'm curious whether other "similar" Pioneer AVRs in the series behave that way. Again, this is when the amplifiers have no load attached.

 

[dlaloum]

The indicator is for protection mode... this is power limiting we're talking about. The amp doesn't shut off... it continues in a lower max power state until restarted.

JSmith

This is an assumption - we don't actually know what this indicator is triggered by.

 

[ivo.f.doma]

This is an assumption - we don't actually know what this indicator is triggered by.

Try putting pink noise or a sine signal into your receiver (of course with disconnected external amplifiers) and observe what happens after 35 seconds. Whether it will be reflected in the PC interface. If I had such a receiver at home, I would try it...

 

[peng]

Try putting pink noise or a sine signal into your receiver (of course with disconnected external amplifiers) and observe what happens after 35 seconds. Whether it will be reflected in the PC interface. If I had such a receiver at home, I would try it...

Should hook up a multimeter to monitor the output voltage to know at what voltage the limiting took effect

 

[Rottmannash]

So I could use REW to send white noise to my RZ50 and watch the web interface and see how long it takes to shut down? How would I know how high to turn the volume? 0dB?

 

[peng]

So I could use REW to send white noise to my RZ50 and watch the web interface and see how long it takes to shut down? How would I know how high to turn the volume? 0dB?

Amir did not get it to shutdown. So we don't know, it's now up to you to find out. It may not even work as suggested using REW because REW may not let you output a high enough signal, and since the Pioneer would go into "limiting", you may not be able to get it to trigger "protection mode" that will shut down the unit, that is, going into standby, unless you can simulate a thermal overload or overcurrent/short circuit event.

 

[Doodski]

Amir did not get it to shutdown. So we don't know, it's now up to you to find out. It may not even work as suggested using REW because REW may not let you output a high enough signal, and since the Pioneer would go into "limiting", you may not be able to get it to trigger "protection mode" that will shut down the unit, that is, going into standby, unless you can simulate a thermal overload or overcurrent/short circuit event.

Slow 'er down there Ace...Lol. Run this as loud as you dare until it triggers the protection Nanny. It's a 440Hz sine wave that won't be uncomfy to crank but it will draw power. See if this bad boy triggers.

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[peng]

Slow 'er down there Ace...Lol. Run this as loud as you dare until it triggers the protection Nanny. It's a 440Hz sine wave that won't be uncomfy to crank but it will draw power. See if this bad boy triggers.

Online Tone Generator - generate pure tones of any frequency

szynalski.com

May be may be not, we don't know how that "limiting", or "pull back"as Amir called it work.. When "cranking", you have to do it in such a way that it will get pass the "limiting/pull back", and go straight to the protect mode.

 

[Doodski]

May be may be not, we don't know how that "limiting", or "pull back"as Amir called it work.. When "cranking", you have to do it in such a way that it will get pass the "limiting/pull back", and go straight to the protect mode.

If it is a crowbar configuration it might trip, pull back or trigger/limit. Yamaha schematics are available and they show the 4 Ohms limiting and power output drawback is done in the Volume IC. Pioneer may be doing it this way too.

 

[peng]

If it is a crowbar configuration it might trip, pull back or trigger/limit. Yamaha schematics are available and they show the 4 Ohms limiting and power output drawback is done in the Volume IC. Pioneer may be doing it this way too.

Possibly, might also be done by limiting the input signal. The suggested test can at least confirm as Amir said, that there would be no indicator on the web UI for the pull back event, or there is, however unlikely.

 

[Doodski]

might also be done by limiting the input signal.

What difference would this make? Input IC Vs Volume IC? Input circuitry would benefit by not attenuating at all and the Volume IC presumably has DSP within.

 

[amirm]

My guess would be that supply rails are reduced to make this happen. At least this is what I would do. As such, the schematic may be revealing there.

 

[DavidMcRoy]

Just do what I've done countless times with a VSX-LX503: feed it pink noise at -10dB on any channel with the volume set at say, -21 or so on the front panel display with NO speakers attached. After a while you'll start hearing a series of relay clicks in the AVR. During this sequence, (it'll take several minutes...far longer than 35 seconds) the whole unit will shut down.

Maybe some of those relay clicks before shutdown are associated with the engagement of the "power limiting" mode?

 

[Doodski]

My guess would be that supply rails are reduced to make this happen. At least this is what I would do. As such, the schematic may be revealing there.

I am presuming you are on the platform/floor of a IC in design mode...Lol. I just look as far as the service manual flowcharts and layout for ICs and determine what kind of operation is occurring internally.

 

[peng]

What difference would this make? Input IC Vs Volume IC? Input circuitry would benefit by not attenuating at all and the Volume IC presumably has DSP within.

Many volume ICs dont have dsp build in, such as D+M's NJU72343.

 

[peng]

My guess would be that supply rails are reduced to make this happen. At least this is what I would do. As such, the schematic may be revealing there.

If they lower the rail voltage, the power amp will clip sooner, and the preout SINAD would likely drop quickly like the Denon AVRs did in your measurements on them.

The Pioneer's preout SINAD remained high during the pull back, so I think Doodski's is more likely right, that the limit is done on the input signal to the power amp, effectively lowering/limiting the gain, instead of the rail voltage.

We are just guessing though.

 

[dlaloum]

My guess would be that supply rails are reduced to make this happen. At least this is what I would do. As such, the schematic may be revealing there.

I don't believe anyone has seen the current generation schematics yet...

Has anyone seen the previous generation schematics (should be well nigh identical!) - LX504?

 

[BJL]

Slow 'er down there Ace...Lol. Run this as loud as you dare until it triggers the protection Nanny. It's a 440Hz sine wave that won't be uncomfy to crank but it will draw power. See if this bad boy triggers.

Online Tone Generator - generate pure tones of any frequency

szynalski.com

Might be more interesting to use music, something like what we actually listen to, to find out when/if the "nanny" protection kicks in? I don't actually listen to sine waves (or pink noise). This could also be useful for anyone who wants to leave the height channels on the internal amps, and offload the main 5 or 7 to an external power amp.

I don't see at all why it matters at all if the amplifiers go into some kind of protection mode with high levels of pink noise or a sine wave. The only time I use pink noise or sine waves is when calibrating Dirac. More relevant when/if it goes into a protection mode with music (or a movie, whatever). This relates back to the cognitive dissonance mentioned earlier - those of us actually using the Pioneer seem mostly pleased with the audio, though I personally prefer an external amp at least for the main five channels.