THX Launches Website to Compare AV Products

gene

gene

Audioholics Master Chief
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#1
THX recently launched a website to "objectively" compare AV consumer products. But is it without bias?

Here is a sneak peek into our analysis of their website. This article isn't published yet but I welcome your feedback before it goes live on Monday.

THX-standard.jpg


See: THX Standard Website: Objective or Biased?
 
M Code

M Code

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#2
Gene..
Note a couple of points when THX is measuring an amplifier's output power.
1. Amplifier is run 10 minutes of pre-conditioning before any measurements
2. Besides testing with just a load resistor, THX also has a capacitance stability test. The load resistance is replaced by a resistor of value 1 kilohms ±1% of adequate power rating in parallel with a switched capacitance load which can be varied from 100 pF ±10% to 100 nF ±10% in steps of 1, 3.3, 10 (seven values. Their test procedure is to increase the input voltage so that the output voltage is equal to the rated value. For each of the seven values of load capacitance, the input voltage to the amplifier is decreased smoothly to zero and then increased back to its original value (giving rated output voltage),while monitoring the oscilloscope display for any signs of instability. And then finally this procedure is then repeated with an additional parallel resistive load of 3.2 ohms ±1%.

Just my $0.02... ;)
 
gene

gene

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#3
Gene..
Note a couple of points when THX is measuring an amplifier's output power.
1. Amplifier is run 10 minutes of pre-conditioning before any measurements
2. Besides testing with just a load resistor, THX also has a capacitance stability test. The load resistance is replaced by a resistor of value 1 kilohms ±1% of adequate power rating in parallel with a switched capacitance load which can be varied from 100 pF ±10% to 100 nF ±10% in steps of 1, 3.3, 10 (seven values. Their test procedure is to increase the input voltage so that the output voltage is equal to the rated value. For each of the seven values of load capacitance, the input voltage to the amplifier is decreased smoothly to zero and then increased back to its original value (giving rated output voltage),while monitoring the oscilloscope display for any signs of instability. And then finally this procedure is then repeated with an additional parallel resistive load of 3.2 ohms ±1%.

Just my $0.02... ;)
Thanks for the info, but where is this found on their new website? All of the power tests there appear to be done in purely resistive loads from what is noted in their results.
 
KEW

KEW

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#4
I just scanned it, but read the THD vs Output Power section that interested me. I thought the use of "their own" (in bold below) was ambiguous. Not sure if it is THX's own measurement or Emotiva's!
I would guess it was THX's, but given Emotiva has been mentioned twice since the last time THX was mentioned...
It is quite puzzling how THX measured the Monolith-7 as having the same power (200 watts) into 8-ohm and 4-ohm loads while most of the other amps they tested delivered 1.5-2X the power into 4-ohm loads. Yet, somehow the Monolith-7 scored an 84 while the Emotiva XPA-7 Gen3 scored a 73 despite the Emotiva amp having delivered 2X its 8-ohm power into a 4-ohm load (500 watts) according to their own testing! Once again, we have no way of determining how THX derives their scoring for this category.
 
B

Blue Dude

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#5
The interesting thing is that THX still thinks it's relevant. That's so adorable.
 
gene

gene

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#6
I just scanned it, but read the THD vs Output Power section that interested me. I thought the use of "their own" (in bold below) was ambiguous. Not sure if it is THX's own measurement or Emotiva's!
I would guess it was THX's, but given Emotiva has been mentioned twice since the last time THX was mentioned...
No I meant THX testing. I will clarify.
 
M Code

M Code

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#7
Thanks for the info, but where is this found on their new website? All of the power tests there appear to be done in purely resistive loads from what is noted in their results.
Gene..
The mentioned test criteria is from the original THX certification tests. However in their revised tests perhaps this was relaxed or deleted...

Just my $0.02... ;)
 
gene

gene

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#8
Gene..
The mentioned test criteria is from the original THX certification tests. However in their revised tests perhaps this was relaxed or deleted...

Just my $0.02... ;)
I'm only going off what is on their new website. I wouldn't make assumptions that anything they did in the past was carried over. I've sent this article to a few manufacturers for peer and they are in agreement with my viewpoints.
 
M Code

M Code

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#9
I'm only going off what is on their new website. I wouldn't make assumptions that anything they did in the past was carried over. I've sent this article to a few manufacturers for peer and they are in agreement with my viewpoints.
Gene..
As I posted previously, we have done Dolby, DTS, THX, HDMI, SimPlay, CEC, Apple certification testing for some of the major audio/video brands for many years. As well as the overall product definition/development/sourcing tasks for the respective brands.

IMHO..
The THX certification process was by far the most demanding and comprehensive... :eek:
In fact, I recall a few years back, I spent about 2 weeks in San Raefel at the THX testing lab along with our Far-East AVR development team going over all of the THX tests and specs. In certain instances THX requested some counter actions, and finally I got to the point under pressure from the AVR brand to finish the certification process I told THX to accept things AS-IS or we would pull out of the THX program. Corporate brand management was getting impatient and wanted to ship the product. THX gave in on certain issues....

Bottom line...
THX specifications for Ultra 2 and Select were very rigorous and maybe in certain instances too strict for a consumer product. But they laid the foundation for processor/controller specs, multi-channel amplifier performance, bass management, on-screen text designations so I do give THX alot of credit...

Just my $0.02.. ;)
 
gene

gene

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#11
Gene..
As I posted previously, we have done Dolby, DTS, THX, HDMI, SimPlay, CEC, Apple certification testing for some of the major audio/video brands for many years. As well as the overall product definition/development/sourcing tasks for the respective brands.

IMHO..
The THX certification process was by far the most demanding and comprehensive... :eek:
In fact, I recall a few years back, I spent about 2 weeks in San Raefel at the THX testing lab along with our Far-East AVR development team going over all of the THX tests and specs. In certain instances THX requested some counter actions, and finally I got to the point under pressure from the AVR brand to finish the certification process I told THX to accept things AS-IS or we would pull out of the THX program. Corporate brand management was getting impatient and wanted to ship the product. THX gave in on certain issues....

Bottom line...
THX specifications for Ultra 2 and Select were very rigorous and maybe in certain instances too strict for a consumer product. But they laid the foundation for processor/controller specs, multi-channel amplifier performance, bass management, on-screen text designations so I do give THX alot of credit...

Just my $0.02.. ;)
Yes agreed that THX did lay some good groundwork back in the day, especially with bass management. They were a different company back then for sure. By today's perspective however, their stuff on dipole speakers for surrounds is particularly dated in the world of discrete surround sound and immersive audio.
 
RichB

RichB

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#12
The burst power is an example where there is an interesting metric but rating the Benchmark over the NAD is absurd when the NAD is considerably more powerful.

If 400 watts is required at 4 ohms for a "burst", then the NAD will deliver it and the AHB2 will be 204 watt shy. This is a new definition of expectation bias. :)

Here are the bust mode measurements for the Monolith versus the Anthem:

BurstPowerMonilithAnthem.jpg


Once again, the M7 gets a lower score though it significantly bests the PVA7.
Perhaps, it is intended to measure with the expected power supply of the amp but I suspect the audience for this site wont get that distinction.

Theoretically, a 25 watt amp could be measured that scores perfect 100 if it can double down to 2 ohms with the correct power limiters in place.

- Rich
 
P

PENG

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#14
The THX certification process was by far the most demanding and comprehensive... :eek:

Bottom line...
THX specifications for Ultra 2 and Select were very rigorous and maybe in certain instances too strict for a consumer product.
That's informative, but then why do you think those THX Ultra 2 certified Onkyo such as the TX-SR805 through 906 didn't seem to be all that reliable?

Also, their S&V power outputs into 8 and 4 ohms were only about the same or lower than their Denon Counterparts such as the AVR-3808 and 4308CI in both 8 and 4 ohm load. I know the test protocols S&v bound to be different, but still, they were tested in the same S&V lab so the comparisons were still apple to apple. If they did good in the more demanding lab, they should also do good/better in the S&V lab, relative to products that were not certified.
 
P

PENG

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#15
The burst power is an example where there is an interesting metric but rating the Benchmark over the NAD is absurd when the NAD is considerably more powerful.

If 400 watts is required at 4 ohms for a "burst", then the NAD will deliver it and the AHB2 will be 204 watt shy. This is a new definition of expectation bias. :)

Here are the bust mode measurements for the Monolith versus the Anthem:

View attachment 24156

Once again, the M7 gets a lower score though it significantly bests the PVA7.
Perhaps, it is intended to measure with the expected power supply of the amp but I suspect the audience for this site wont get that distinction.

Theoretically, a 25 watt amp could be measured that scores perfect 100 if it can double down to 2 ohms with the correct power limiters in place.

- Rich
Seems to me the whole thing is clear as mud..:D Hopefully Gene will figure out what's going on by getting some answers from the authorities.
 
M Code

M Code

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#16
That's informative, but then why do you think those THX Ultra 2 certified Onkyo such as the TX-SR805 through 906 didn't seem to be all that reliable?

Also, their S&V power outputs into 8 and 4 ohms were only about the same or lower than their Denon Counterparts such as the AVR-3808 and 4308CI in both 8 and 4 ohm load. I know the test protocols S&v bound to be different, but still, they were tested in the same S&V lab so the comparisons were still apple to apple. If they did good in the more demanding lab, they should also do good/better in the S&V lab, relative to products that were not certified.
We actually managed the software development team for the Onkyo 605 and 805...
IMHO..
Both of these AVRs were major breakthroughs especially for HDMI features.. If we were to do those products over again we would have changed (2) things.
1. Output stage bias settings were high to minimize X-over distortion. Unfortunately the raises the idle current and has significant heat buildup. If the user didn't provide adequate free-air space 4-5" for L/R sides and don't stack any component on top as noted in the setup guide, or else the heat buildup may cause some reliability issues..
2. The rear panel HDMI connectors though in-spec to HDMI standards could not handle the oversize Monster HDMI cables. The molded connectors on the Monster cables were slightly oversized and if forced into the rear panel HDMI connectors, caused significant stress on the HDMI jack's PCB solder joints. Possible resulting in frequent intermittent audio/video operation.

Both the 605 & 805 were major sellers as they were introduced about 6-8 months ahead of comparable featured competitive AVRs. Overall global sales for both models was well into 6 figures each, yet some of the reported failure modes were heavily debated on certain internet forums. Here Onkyo probably could have handled the overall situation better..

Note that I still have 1 of the original 805 pre-production samples in a 3rd HT system and its been operating for over 8 1/2 years no reliability issues..

Just my $0.02... ;)
 
BoredSysAdmin

BoredSysAdmin

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#17
That's informative, but then why do you think those THX Ultra 2 certified Onkyo such as the TX-SR805 through 906 didn't seem to be all that reliable?
805 runs hot. From the anecdotical/forums members experience, it seems like placing it in air constrained spaces and high failure rate has a direct correlation.
My 805 so far (knocking on wood) had only 1 issue and it was a known bug with display resistors fail. It was very cheap to fix.
 
gene

gene

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#18
NAD confirmed to me that the THX Frequency response graphs aren't correct and they also were puzzled by the power burst test results. This is getting interesting.
 
P

PENG

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#19
805 runs hot. From the anecdotical/forums members experience, it seems like placing it in air constrained spaces and high failure rate has a direct correlation.
My 805 so far (knocking on wood) had only 1 issue and it was a known bug with display resistors fail. It was very cheap to fix.
My Denon 3805 and 4308 are both running in top conditions (as far as I know) and never had any trouble, but for the hot running 805, also 10-11 years old to have only a cheap to fix known bug is excellent too, consider it's launch price was very low relatively speaking. I suppose if you put one of those Infinity fan on top, it may last another 10 years for you.:)

I remember liking the 805 a lot at the time, lowest $/watt, but I had the 4308 already at the time. I asked M Code those questions because I am curious about the fact that being THX Ultra certified, and about 7-8 lbs heavier, it's S&V HT lab measured power output and distortions were not as good as Denon's, still impressive though. I believe the THX power output test protocol are as strict as M Code said they were, but other brands such as Denon and Yamaha didn't get their non flagship models done just to avoid adding cost.
 
gene

gene

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#20
My Denon 3805 and 4308 are both running in top conditions (as far as I know) and never had any trouble, but for the hot running 805, also 10-11 years old to have only a cheap to fix known bug is excellent too, consider it's launch price was very low relatively speaking. I suppose if you put one of those Infinity fan on top, it may last another 10 years for you.:)

I remember liking the 805 a lot at the time, lowest $/watt, but I had the 4308 already at the time. I asked M Code those questions because I am curious about the fact that being THX Ultra certified, and about 7-8 lbs heavier, it's S&V HT lab measured power output and distortions were not as good as Denon's, still impressive though. I believe the THX power output test protocol are as strict as M Code said they were, but other brands such as Denon and Yamaha didn't get their non flagship models done just to avoid adding cost.
Denon and Yamaha used to get THX certified. I actually advised Yamaha to drop the THX after 2 generations bc they already easily met all the specs anyways. The THX name lost relevancy in consumer audio over the years especially since consumers weren't demanding it in their product purchasing decisions as a major factor.
 

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