Emotiva UPA-500 Five Channel Power Amplifier Review

[KEW]

Compared to the Emotiva, the Outlaw Model 5000 represents a better deal with, more detailed and complete and I believe, honest power and THD ratings. It's ACD power figures would indicate a more powerful power supply than that of Emotiva's UPA500.
The looks may not be as appealing as that of the Emotiva, so what? It's the performance that counts.

The Outlaw 5000 does indeed appear to be more realistic with its ratings. No transformer spec but it weights a few lbs more than the 885 I just bought. That said the Outlaw 5000 is rated at 44% higher than the 885a at 4 ohms. The 885a is probably even more conservatively rated.

No need to speculate. AH ran the tests on the Outlaw 5000.
I think it is definitely a value leader. As a matter of fact, I will generally recommend it to someone looking for a strong 2 channel amp! At $600, I don't know of a 2 channel that can beat it (and you have the flexibility to add 3 more channels depending on future situations).
http://www.audioholics.com/amplifier-reviews/outlaw-5000/measurements

Especially impressive are the THD+N spec for 1kHz powersweep with all 5 channels driven. That looks like about 0.007% or better up to 130WPC! That reflects a quality design/build!

Also, the AH review states:
The Model 5000 is a traditional Class AB amplifier design with four output devices per channel in a mono-block configuration fed from a large centralized toroidal power supply that appears to be at least 1kVA rated.

 

[nickwin]

No need to speculate. AH ran the tests on the Outlaw 5000.
I think it is definitely a value leader. As a matter of fact, I will generally recommend it to someone looking for a strong 2 channel amp! At $600, I don't know of a 2 channel that can beat it (and you have the flexibility to add 3 more channels depending on future situations).
http://www.audioholics.com/amplifier-reviews/outlaw-5000/measurements

Especially impressive are the THD+N spec for 1kHz powersweep with all 5 channels driven. That looks like about 0.007% or better up to 130WPC! That reflects a quality design/build!

Also, the AH review states:
The Model 5000 is a traditional Class AB amplifier design with four output devices per channel in a mono-block configuration fed from a large centralized toroidal power supply that appears to be at least 1kVA rated.

Im not denying that the 5000 might be a good amp and it proably is a great value, but but my comments are hardly speculation. I was talking specifically about ACD measurements and even more specifally 4 ohm ACD measurements. Just like the AH UPA500 review AH provides no 4ohm ACD measurements, not even 1khz or dynamic let alone 20-20khz.

This passage from the AH review is downright misleading:
The Model 5000 produced commendable results by belting out over 210 watts/ch into 8 ohms, all channels driven at 1% THD+N and almost 400 watts/ch into 4 ohm."

Wow that sounds awesome! But the forgot to mention in that passage that the 400 watts/ch into 4 ohm figure is one channel driven. Its hardly a per channel measurement when its one channel driven is it?

I wonder what it does ACD? I wonder why we see no 4 ohm ACD measurements? I can think one one possible reason. Its very unlikely that a class AB amp with a ~1Kva transformer will be able to output 900 watts continuously. For a few cycles maybe but continuously?

I don't buy the argument that 4 ohm ACD tests are "unrealistic". Its hardly unrealistic for those of us who have all 4 ohm speakers and there are a lot of us. Also, if 4 ohm ACD tests are unrealistic doesn't that make 4 ohm ACD specs unrealistic by nature too?

If thats really the case then we should use a different metric but whatever metric is used, companies should be realistic with them.

PS, that 2 channel driven @ 8 ohm power vs THD graph is pretty impressive.

 

[PENG]

Im not denying that the 5000 might be a good amp and it proably is a great value, but but my comments are hardly speculation. I was talking specifically about ACD measurements and even more specifally 4 ohm ACD measurements. Just like the AH UPA500 review AH provides no 4ohm ACD measurements, not even 1khz or dynamic let alone 20-20khz.

This passage from the AH review is downright misleading:
The Model 5000 produced commendable results by belting out over 210 watts/ch into 8 ohms, all channels driven at 1% THD+N and almost 400 watts/ch into 4 ohm."

Wow that sounds awesome! But the forgot to mention in that passage that the 400 watts/ch into 4 ohm figure is one channel driven. Its hardly a per channel measurement when its one channel driven is it?

I wonder what it does ACD? I wonder why we see no 4 ohm ACD measurements? I can think one one possible reason. Its very unlikely that a class AB amp with a ~1Kva transformer will be able to output 900 watts continuously. For a few cycles maybe but continuously?

I don't buy the argument that 4 ohm ACD tests are "unrealistic". Its hardly unrealistic for those of us who have all 4 ohm speakers and there are a lot of us. Also, if 4 ohm ACD tests are unrealistic doesn't that make 4 ohm ACD specs unrealistic by nature too?

If thats really the case then we should use a different metric but whatever metric is used, companies should be realistic with them.

PS, that 2 channel driven @ 8 ohm power vs THD graph is pretty impressive.

As I mentioned before, "continuous" as used in some of those lab measurements are not meant to be literally continuous. It apparently meant a continuous sine wave, as opposed to some sort of a pulse. So you are right, the test duration could be from a few cycles to a few seconds. Or it may be for a minute of 2 but not more. If I can find more information I'll post a link for you.

As AH and other online resource have explained, ACD capability is not really as important as a lot of people think for real world use in music or movie enjoyment, except for something like 5,7 channel stereo.

Given a fixed budget amount for an amp, it is better to optimize performance in 1,2 or even 3 channel driven power output rather than all 7 (even 11 channels nowadays if you want to insist on ACD). If that means focus more on the amp section instead of overspending (relatively) on the power supply transformer and capacitors, I am all for it. HK used to focus on their ability to claim the so called "honest" watts based on their ACD rating, look at where they are today. Lab tests after lab tests showed that their W/$ for practical use just wasn't competitive.

 

[KEW]

@nickwin
Your points are well taken.
I did not realize you had seen the review.
I would say if the tests that were done validate the manufacturers claims, it is reasonable to believe that the other manufacturer claims are accurate, but there is no way to know for sure.

Do you know if AH ever measures ACD for 4 ohms?
I checked a couple of multichannel amps and they did not on those.
I was especially annoyed by the lack of a 2 channel CFP-BW measurements into 4 Ohms for the Yamaha RX-A860 AVR because that is a measurement they made on every other review. Normally, I might think it was an oversite, but given that the 860 is clearly lacking for an adequate power supply, it seems very likely that measurement would be conspicuously poor.

It is an unfortunate reality that reviewers depend on manufacturers to provide sponsorship and units for testing, and it seems no one is totally immune to the influence this allows.

 

[nickwin]

As I mentioned before, "continuous" as used in some of those lab measurements are not meant to be literally continuous. It apparently meant a continuous sine wave, as opposed to some sort of a pulse. So you are right, the test duration could be from a few cycles to a few seconds. Or it may be for a minute of 2 but not more. If I can find more information I'll post a link for you.

As AH and other online resource have explained, ACD capability is not really as important as a lot of people think for real world use in music or movie enjoyment, except for something like 5,7 channel stereo.

Given a fixed budget amount for an amp, it is better to optimize performance in 1,2 or even 3 channel driven power output rather than all 7 (even 11 channels nowadays if you want to insist on ACD). If that means focus more on the amp section instead of overspending (relatively) on the power supply transformer and capacitors, I am all for it. HK used to focus on their ability to claim the so called "honest" watts based on their ACD rating, look at where they are today. Lab tests after lab tests showed that their W/$ for practical use just wasn't competitive.

I agree that continuous ACD tests are not representative of most real world content, but its still useful because it tells you what an amp will handle in a worse case scenario. For example, if you talking about movies, and can say at x volume my amp could theorretically draw x watts on all channels symultaniously. If you know what your amp can actually do ACD, you can be 100% sure that you won't drive your amp into clipping. Without an accurate ACD spec you really don't know for sure when the amp will hit the rails when theres signal being fed to all channels.

Even if we agree that ACD specs are not the best metric, continuing to to use that metric and just fudging the numbers is not the solution. IMO if we have a REAL continuous ACD spec and a per channel dynamic power spec, we have a pretty good idea what the amp is really capable of at both extremes and can plan accordingly.

 

[nickwin]

@nickwin
Your points are well taken.
I did not realize you had seen the review.
I would say if the tests that were done validate the manufacturers claims, it is reasonable to believe that the other manufacturer claims are accurate, but there is no way to know for sure.

Do you know if AH ever measures ACD for 4 ohms?
I checked a couple of multichannel amps and they did not on those.
I was especially annoyed by the lack of a 2 channel CFP-BW measurements into 4 Ohms for the Yamaha RX-A860 AVR because that is a measurement they made on every other review. Normally, I might think it was an oversite, but given that the 860 is clearly lacking for an adequate power supply, it seems very likely that measurement would be conspicuously poor.

It is an unfortunate reality that reviewers depend on manufacturers to provide sponsorship and units for testing, and it seems no one is totally immune to the influence this allows.

Actually, yes. Here is a excerpt from the AH Parasound A51 review:

"I was able to measure about 250 watts into an 8 ohm load and about 400 watts into a 4 ohm load across the entire audio bandwidth. Please note that during the 4 ohm load test, my wall voltage sagged from 116VAC to 112VAC. Without having a VARIAC to hold the line voltage constant, it is difficult to accurately measure all channels driven with such a powerful amplifier. However, given the fact that the A 52 is endowed with a 2.2 kVA transformer and 164,000uF power supply, I think it's safe to assume this amp will deliver its rated power into all channels at 8 ohms. It will deliver marginally close to its rated power into 4 ohms. In order to do a true 400 watts/ch into 4 ohms continuously, would require a power transformer about 65% larger than the one in the A 52."

*I believe a52 is a type this should read a51*

This is the real deal. An honest, no BS approach to power rating and testing. They even taxed it in the score card for this:
Measured Power (4-ohms)

This is exactly what Im pushing for. Funny that they didn't hesitate to point out that even with 2.2KVA its still not enough to hit the rated 4 ohm ACD spec. This is an amp with with 1.1VA/watt yet they say nothing about the UPA500 with its measly .58VA/watt (actually, worse than saying nothing, they said it was "honestly rated"). Thats as biased as it gets. They also don't hesitate to throw AVR makers under the bus for this kind of thing.

I think you nailed it in your last paragraph. That said, it rubs me the wrong way when a publication thats getting something in return from a manufactuer tries to act like they are unbiased, going so far as selling there "unbiased" information to consumers. They're working both sides! I'd certainly never pay for this "unbiased" information, knowing what I know now.

 

[PENG]

I agree that continuous ACD tests are not representative of most real world content, but its still useful because it tells you what an amp will handle in a worse case scenario. For example, if you talking about movies, and can say at x volume my amp could theorretically draw x watts on all channels symultaniously. If you know what your amp can actually do ACD, you can be 100% sure that you won't drive your amp into clipping. Without an accurate ACD spec you really don't know for sure when the amp will hit the rails when theres signal being fed to all channels.

I can agree to some extent, but do have to make the following points:

1. Even in THX movie cinemas, you can expect to get 85 dB average, with peaks to 105 dB. That tells me in most HT rooms, especially those with one or more good subwoofers, will not need their 100-150WPC AVRs and/or amps to be capable of the same 100-150 WPC X7 ACD, and continuously rated. You can do the math yourself to confirm this.

2. Again, given a budget, the AVR/amp design team has to make choices. If I were the design team leader, recognizing the nature of music and movie sound track contents, I would focus on dynamic capability, not the ACD and "continuous" criteria. That means an amp capable of higher "continuous" and dynamic output at low distortion level when 2 to 3 channel are driven to such levels, would be preferred to one that offers lower output level but can maintain this lower output level under ACD and "continuous" condition.

So while I do agree with you that lab measurements should include the ACD results, and that such results will be useful for comparison purposes, I believe you will find that everything else being equal, amps designed and optimized to match the need of real world music and sound track contents that are dynamic in nature will prevail, simply because if more money is spent on the power supply, less money will be spent on the electronics.

Even if we agree that ACD specs are not the best metric, continuing to to use that metric and just fudging the numbers is not the solution. IMO if we have a REAL continuous ACD spec and a per channel dynamic power spec, we have a pretty good idea what the amp is really capable of at both extremes and can plan accordingly.

This is the one point that I can fully agree with you. The same goes for the so called "continuous" (minutes) and "literally continuous" (no time limit) rating tests.

One also should keep in mind that most 100-200 WPC AVR or amp users simply plug their gear into a 15A outlet that may or may not be shared with other loads. For class AB amps, that means the maximum continuous load cannot exceed about 700-750W based on 50% efficiency and a power factor of 0.8. So even if you have music contents that demands both ACD and "Continuous" power, it will still be a moot point in most cases.

 

[nickwin]

I can agree to some extent, but do have to make the following points:

1. Even in THX movie cinemas, you can expect to get 85 dB average, with peaks to 105 dB. That tells me in most HT rooms, especially those with one or more good subwoofers, will not need their 100-150WPC AVRs and/or amps to be capable of the same 100-150 WPC X7 ACD, and continuously rated. You can do the math yourself to confirm this.

Hmm, lets do the math. Lets say an avg sensitivity consumer speaker is 88db/1watt/1meter and an average listening distance is 10'. In this scenario 150 watts will only give you 100db. It would take 475 watts to hit 105db. Sure, it doesn't take a 475 watt continuous rated amp to hit 105db peaks, but it will take around that much to do it clearly with minimal distortion and compression, and thats not even allowing any headroom. 3db of headroom requires twice the wattage. THX reference level is no joke, it takes substantial amplification (again talking typical consumer speakers) and very robust speakers.

If the only power spec you have is 1 or two channels driven, how do you know what the amps going to do when the content calls for dynamic peaks on 5 or even 7 channels simultaneously?

 

[PENG]

Hmm, lets do the math. Lets say an avg sensitivity consumer speaker is 88db/1watt/1meter and an average listening distance is 10'. In this scenario 150 watts will only give you 100db. It would take 475 watts to hit 105db. Sure, it doesn't take a 475 watt continuous rated amp to hit 105db peaks, but it will take around that much to do it clearly with minimal distortion and compression, and thats not even allowing any headroom. 3db of headroom requires twice the wattage. THX reference level is no joke, it takes substantial amplification (again talking typical consumer speakers) and very robust speakers.

Your math doesn't seem right. Try this calculator:
http://myhometheater.homestead.com/splcalculator.html

I can assure you that the above linked calculator is correct as I checked it with the spreadsheets I set up for such calculations, though the room gain part is obviously just some sort of room of thumb.

Also, please remember lab measurements are typically based on sine waves so if you want to talk about a tested 150 WPC rms (average), implies 300 W peak, that is an extra 3 dB build in for the peaks.

If the only power spec you have is 1 or two channels driven, how do you know what the amps going to do when the content calls for dynamic peaks on 5 or even 7 channels simultaneously?

Dynamic ACD specs will be useful for sure. Reality is, most manufacturers don't provide such specs, those that do, typically are not specific enough, e.g. not specifying the duration. Regardless, there are probably enough lab measurements from the likes of S&V, HTM, Avtech, Audioholics to give us a good idea of the 5,7 channel driven output performance of the popular AVRs and amps.

 

[nickwin]

Your math doesn't seem right. Try this calculator:
http://myhometheater.homestead.com/splcalculator.html

I can assure you that the above linked calculator is correct as I checked it with the spreadsheets I set up for such calculations, though the room gain part is obviously just some sort of room of thumb.

Thats the calculator I just used to give you those figures! Type it in and see. Put speaker placement to "away from wall" which is 4 or more feet which is good practice anyway. Number of speakers to 1 because where talking individual channel peaks.

Also, please remember lab measurements are typically based on sine waves so if you want to talk about a tested 150 WPC rms (average), implies 300 W peak, that is an extra 3 dB build in for the peaks.

Its typically more like 1-2db for most amps. So 300 watts instead of 475. But, keep in mind dynamic peaks beyond rated power may have significantly higher distortion.

Dynamic ACD specs will be useful for sure. Reality is, most manufacturers don't provide such specs, those that do, typically are not specific enough, e.g. not specifying the duration. Regardless, there are probably enough lab measurements from the likes of S&V, HTM, Avtech, Audioholics to give us a good idea of the 5,7 channel driven output performance of the popular AVRs and amps.

I agree with all this except the last bit, at 8 ohms yes, but hardly anyone does ACD tests at 4ohms. In fact that AH Parasoud a51 review is one of the only ones I can come up with, probity because its one of the few multichannel amps being reviewed that can actually come close to hitting its 4 ohm ACD rating. Even in that case I don't think we actually got a hard number.

 

[PENG]

That is the calculator I just used to give you those figures! Type it in and see. Put speaker placement to "away from wall" which is 4 or more feet which is good practice anyway. Number of speakers to 1 because where talking individual channel peaks.

Then you are ignoring room gain. I did not know you were talking about 1 channel. Even FTC requires manufacturers to specify their power output with 2 channels driven. THX standard's 85 dB reference is not based on 1 channel either. So I guess we disagree on this one.

Its typically more like 1-2db for most amps. So 300 watts instead of 475. But, keep in mind dynamic peaks beyond rated power may have significantly higher distortion.

I don't know what the 1-2dB you are referring to. the 3 dB peak I mentioned is based on sine wave. For sine wave, V peak = √2 X Vrms, since Power = V^2/Z, so Power peak = 2X average power, 2X power gives 3 dB more spl. That has nothing to do with the "headroom" often specified by power amp manufacturers. If there is such a spec provided, that would be on top.

I agree with all this except the last bit, at 8 ohms yes, but hardly anyone does ACD tests at 4ohms. In fact that AH Parasoud a51 review is one of the only ones I can come up with, probity because its one of the few amps being reviewed that can actually come close to hitting its 4 ohm ACD rating.

Not necessarily ACD as we now have 11 channels to deal with, but I thought I had seen measurements for 5 channels into 4 ohms a few times but for the most part I agree with you. Again, I do feel it would be great to see them specifying ACD into 8 and 4 ohms based on say 200ms duration. Any longer than that you risk smoke, blown fuses etc., not too bad with 5 channels, but would be bad to 7,9 and 11 channels.

Now if you really believe ACD is important for you then you may want to have a couple of dedicated 20A or higher outlets, like I do in my HT room. Then go get your MCH power amps such as a A51 and some, depending on the number of channels you need. I have 11 channels of power amps for my AVP for only 7 channel speakers, yet I have never experienced a single movie or MCH music that would call for ACD to anywhere near the amps rated output.

Below links to an article that seems interesting as it claimed "technical notes".. I just scanned it quickly so not sure if I would agree to everything in it.

http://www.rocketroberts.com/techart/powerart_a.htm

 

[nickwin]

Then you are ignoring room gain. I did not know you were talking about 1 channel. Even FTC requires manufacturers to specify their power output with 2 channels driven. THX standard's 85 dB reference is not based on 1 channel either. So I guess we disagree on this one.

Correct. Without taking an actual measurment its hard to say exactly how much room gain if any you are getting in your particuar room. And even if you do it might only be in the lower frequencies. Im almost certain THX allows peak up to 105db at any frequency, on any given indiviudal channel. Am I wrong on that?

I don't know what the 1-2dB you are referring to. the 3 dB peak I mentioned is based on sine wave. For sine wave, V peak = √2 X Vrms, since Power = V^2/Z, so Power peak = 2X average power, 2X power gives 3 dB more spl. That has nothing to do with the "headroom" often specified by power amp manufacturers. If there is such a spec provided, that would be on top.

You may be right on this one. I was referencing this from Crown Audio:

• "According to Crown's chief amplifier engineer, Gerald Stanley, amplifier continuous power and amplifier peak power are nearly the same. Typically, peak power is only 1 dB higher than continuous power, and depends on peak duration."

Is this the wrong context? I always interpreted "peak" in the context of thx reference level as short term dynamic peaks in the content, not the peak of an individual waveform.

 

[PENG]

Correct. Without taking an actual measurment its hard to say exactly how much room gain if any you are getting in your particuar room. And even if you do it might only be in the lower frequencies. Im almost certain THX allows peak up to 105db at any frequency, on any given indiviudal channel. Am I wrong on that?

You are not wrong as such, but you should look deeper into the details. Let's say you have a D&M AVR just for example. If you run Audyssey following instructions, your system will be set up to provide you with 85 dB at your main mic positions with master volume set to 0. That is in fact per channel, i.e. one channel.

Since we are talking about THX standard for HT applications right, we should read up on their website. In the linked page below, you will find more details about what they test for certification.

http://www.thx.com/certification/thx-certified-av-receivers/

"Power output is tested to ensure the receiver accurately plays source material at
THX Reference Level in every input and mode and at every sampling rate for all
possible playback combinations selected by the listener."

If you read on, they listed 5 listening "modes", not one is mono. I would appear that they referred to 5.1 and 7.1. That makes sense to me because for movies, probably 99.99% of the time more than one speaker would be making sound during the 105 dB peak moments. In fact, there is no "mono" playback the listener can select, the listener can select "stereo", and that's two channels/speakers.

So basically, when you set up your AVR, or AVP+MCH Power amp, you do set up/calibrate each (one channel at a time) speaker to give you 85 dB average at the main mic position. That is necessary for calibration purposes because you have no way of predicting how all 5 or 7 speakers would give you on moment by moment basis so there is no way to do any compensation for 2 speakers or more ahead of time. After running set up, you can expect your system to provide 85 dB average and 105 dB peak spl at you main listening/mic position. As mentioned above, you will have more than one speaker working, especially during the 105 dB peak moments.

You may be right on this one. I was referencing this from Crown Audio:

• "According to Crown's chief amplifier engineer, Gerald Stanley, amplifier continuous power and amplifier peak power are nearly the same. Typically, peak power is only 1 dB higher than continuous power, and depends on peak duration."

Is this the wrong context? I always interpreted "peak" in the context of thx reference level as short term dynamic peaks in the content, not the peak of an individual waveform.

I am quite sure Mr. Stanley knows what he's talking about. However, as I guessed in my earlier post, we are talking about two different things here. I believe what Mr. Stanley referred to was what the Crown audio amps could do for short duration, without clipping and that's why it would be almost the same or only 1 dB higher than their continuous ratings.

Regarding the 3 dB peak that I mentioned, there is no "may be right...", it is a fact that for a sine wave, Vpeak=square root 2 X Vrms so Pp=2 X Pavg (or so called Prms).

The reference level of 85 dB THX referred to was clearly meant to be average spl. The 105 dB peak they referred to is not so clear in terms of whether they meant the maximum spl measured with a meter capable of recording peaks, or the maximum average SPL for a short duration.

It seems to me you don't mind reading stuff, so below is another link, along with the one I posted before. So have fun reading, and draw your own conclusion. Just one final note, in the first linked article below, the author claimed:

"Many people also make a simple mistake which effectively doubles the size of amplifier required. Using the online calculators they enter follow a process of trial and error to determine the amplifier size required for 105dB SPL. The issue is that our THX requirement is not for 105dB continuous output but 105dB peak output. More on this later."

I am not sure about that and I think that extra 3 dB should be ignored in order to be on the safe side, unless I can find evidence directly from THX that supports the author's interpretation. I brought this point up just for awareness and discussions.

http://www.acousticfrontiers.com/2013322spl-calculator/
http://www.rocketroberts.com/techart/powerart_a.htm

 

[nickwin]

You are not wrong as such, but you should look deeper into the details. Let's say you have a D&M AVR just for example. If you run Audyssey following instructions, your system will be set up to provide you with 85 dB at your main mic positions with master volume set to 0. That is in fact per channel, i.e. one channel.

Since we are talking about THX standard for HT applications right, we should read up on their website. In the linked page below, you will find more details about what they test for certification.

http://www.thx.com/certification/thx-certified-av-receivers/

"Power output is tested to ensure the receiver accurately plays source material at
THX Reference Level in every input and mode and at every sampling rate for all
possible playback combinations selected by the listener."

If you read on, they listed 5 listening "modes", not one is mono. I would appear that they referred to 5.1 and 7.1. That makes sense to me because for movies, probably 99.99% of the time more than one speaker would be making sound during the 105 dB peak moments. In fact, there is no "mono" playback the listener can select, the listener can select "stereo", and that's two channels/speakers.

So basically, when you set up your AVR, or AVP+MCH Power amp, you do set up/calibrate each (one channel at a time) speaker to give you 85 dB average at the main mic position. That is necessary for calibration purposes because you have no way of predicting how all 5 or 7 speakers would give you on moment by moment basis so there is no way to do any compensation for 2 speakers or more ahead of time. After running set up, you can expect your system to provide 85 dB average and 105 dB peak spl at you main listening/mic position. As mentioned above, you will have more than one speaker working, especially during the 105 dB peak moments.

Good points, thanks for linking your sources. I think we pretty much in agreement on this for the most part.

I do interpret the THX spec a little differently than you do though. You seem to me looking at AVR specs, Im talking about the overarching THX theater spec, which has nothing to do with "modes". Its admittedly a little vague, but the way I understand it its possible within the THX spec to have 105db peaks on any given channel.

From the Acousticfrontiers article you referenced:
"1. Speakers and amplifiers must be capable of 105dB peaks

If the playback chain is calibrated to produce 85dB for a -20dB signal at the listening position then the speakers and amplifiers could be asked to produce 105dB for a 0dB signal."

I read this to mean every speaker and every amp channel. Its within THX spec to have 0db signal on any channel right?

From HometheaterHifi.com:
"Reference level is by any definition, objective or subjective, quite loud. It basically mirrors the dynamic range of the studio system, which in the case of all movie sound tracks, is 105 dB. Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel)."

IMO this one is pretty clear that where talking about per channel SPLs. Now, realistically full on 105db peaks will be pretty rare, but it does happen. If you want to be 100% sure that your amp stays below clipping you need to plan for the worse case scenario.

Here is a AVSforum thread on the subject, where a user with 6000+ posts states:
"Reference level means peaks of up to 105db from the main channels and up to 115db from the LFE channel." And no one disagreed.
http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1252556-what-reference-level.html

If your interpretation is right I'd end up with some extra headroom. On the flip side if my interpretation is right but your system is only capable of 105db cumulative with 5-11 channels driven and it turns out the THX spec actually does allow 105db per channel you will end up regularly driving your amp grossly into clipping which will wreck havoc on your sound quality and your gear. You better be pretty sure about that interpretation! Id rather be safe than sorry.

I don't think anyone is really arguing my original point that many entry level consumer amps are overrated, especially at 4 ohm ACD, and that many Audio publications don't tell the whole story with there measurements. It seems that they don't want to ruffle any feathers. At the end of the day more realistic ratings can only help the consumer not hurt.

Anyway, it was a fun discussion. That said this thread derailed a long time ago and its largely my fault lol. This will (hopefully) be my last post here but maybe Ill start another thread for this kind of discussion.

http://hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-1.html

 

[PENG]

but the way I understand it its possible within the THX spec to have 105db peaks on any channel given channel.

Yes it is possible, but in real world scenario, do you know of one movie scene during which only 1 channel would peak to 105 dB spl? That is regardless of whether you are listening to you own HT system or in the THX cinema. You probably know we are in agreement in theory, but I have been talking about real world applications from the beginning of our discussion.

From the Acousticfrontiers article you referenced:
"1. Speakers and amplifiers must be capable of 105dB peaks

Be careful reading into this one. They, including the THX site, consistently referred to "setup", not in terms of singularity. Note the "s", so again not in singularity, but plural..

If the playback chain is calibrated to produce 85dB for a -20dB signal at the listening position then the speakers and amplifiers could be asked to produce 105dB for a 0dB signal."

I read this to mean every speaker and every amp channel. Its within THX spec to have 0db signal on any channel right?

It never said anything about one channel, always in terms of "set up", for example, in the linked THX webpage it says:

"FEATURED ON ALL CERTIFIED RECEIVERS, THX LISTENING MODES MAKE IT
CONVENIENT TO HAVE ONE SPEAKER SET UP FOR MOVIES, MUSIC AND GAMES."

No one uses one speaker in their "set up" to play movies, surely we can agree on this.

From HometheaterHifi.com:
"Reference level is by any definition, objective or subjective, quite loud. It basically mirrors the dynamic range of the studio system, which in the case of all movie sound tracks, is 105 dB. Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel)."

IMO this one is pretty clear that where talking about per channel SPLs.

Yes this one is pretty clear but you could have quoted me. I did say the system is calibrated to play 85 dB and 105 dB peak didn't I ? I even explained why it has to be done that way. The point I made, again, was that in real world your system, though calibrated to do it, would not require one single speaker to produce that 105 dB peak during a movie playback in 5.1, 7.1 or even stereo mode. Yes we are talking about HT so there is listening mode, but in the cinema the same principle still apply.

I don't think anyone is really arguing my original point that many entry level consumer amps are overrated, especially at 4 ohm ACD, and that many Audio publications don't tell the whole story with there measurements. At the end of the day more realistic ratings can only help the consumer not hurt.

That was clear from start. A parallel point that need to be made though, is that in many cases the need for power is also often overrated. For example, many people like me, have our systems cruise along outputting fractional watt per channel on average, and cannot subject ourselves to THX reference level even though our systems have no trouble reaching 105 dB spl and beyond.

Anyway, it was a fun discussion. That said this thread derailed a long time ago and its largely my fault lol. This will (hopefully) be my last post here but maybe Ill start another thread for this kind of discussion.

I enjoy the discussion, and I don't even consider it being derailed, in the sense that we are in fact discussion power requirements.

 

[nickwin]

PENG, to me its pretty clear that all those quotes on THX spec are saying IF you calibrate an individual channel to 85db @ -20DBSF, that channel will be asked to produce up to 105db (peak, whatever that means in this case) in playback. I certainly don't see anything to the contrary. We may have to agree to disagree on this one. I say again though, if you make the assumption your making, and your wrong, your in for a world of hurt because that makes a massive difference on wattage needs.

As far as being derailed I just mean that this thread has gone far from being about the UPA500. ill start a more general thread and send you a link

Seriously, last post this time haha.

 

[Steve81]

The reference level of 85 dB THX referred to was clearly meant to be average spl. The 105 dB peak they referred to is not so clear in terms of whether they meant the maximum spl measured with a meter capable of recording peaks, or the maximum average SPL for a short duration....

"Many people also make a simple mistake which effectively doubles the size of amplifier required. Using the online calculators they enter follow a process of trial and error to determine the amplifier size required for 105dB SPL. The issue is that our THX requirement is not for 105dB continuous output but 105dB peak output. More on this later."

I am not sure about that and I think that extra 3 dB should be ignored in order to be on the safe side, unless I can find evidence directly from THX that supports the author's interpretation. I brought this point up just for awareness and discussions.

AFAIK, that's the commonly accepted understanding of how it works, i.e. 0dBFS = 105dB peak, not RMS. Indeed, the example given here:
http://www.acousticfrontiers.com/2013314thx-reference-level/

lines up almost perfectly with a simple mix and match of other THX Ultra 2 hardware:
http://atlantictechnology.com/product/6200e-lr/
90dB sensitive, 6 ohm nominal
https://www.soundandvision.com/content/integra-dhc-803-surround-processor-and-dta-701-amplifier-ht-labs-measures
155W into 2 ch @ 8 ohms w/ 0.1% THD+N / 230W into 2 ch @ 4 ohms w/ 0.1% THD+N

Even if you bump up to the 1% numbers for the amp, you're not getting another 3dB worth of headroom out of it.

 

[nickwin]

AFAIK, that's the commonly accepted understanding of how it works, i.e. 0dBFS = 105dB peak, not RMS. Indeed, the example given here:
http://www.acousticfrontiers.com/2013314thx-reference-level/
View attachment 21824
lines up almost perfectly with a simple mix and match of other THX Ultra 2 hardware:
http://atlantictechnology.com/product/6200e-lr/
90dB sensitive, 6 ohm nominal
https://www.soundandvision.com/content/integra-dhc-803-surround-processor-and-dta-701-amplifier-ht-labs-measures
155W into 2 ch @ 8 ohms w/ 0.1% THD+N / 230W into 2 ch @ 4 ohms w/ 0.1% THD+N

Even if you bump up to the 1% numbers for the amp, you're not getting another 3dB worth of headroom out of it.

Just when I think I'm out... They pull me right back in hahaha

So your saying the 105db is peak as in the peak of the waveform? This would be equivalent to 102db RMS, right?

 

[Steve81]

So your saying the 105db is peak as in the peak of the waveform? This would be equivalent to 102db RMS, right?

That's my understanding of it. THX doesn't exactly go out of their way to release technical documentation, but looking at how AH does its room rating protocol for subwoofers, that also ties into 105dB (or 115dB for LFE as the case may be) being an instantaneous peak figure, as opposed to a short term RMS number.

 

[Gmoney]

Actually there is no disagreement in this regard because when I mention AVRs, in my mind (I know no one can read my mind) I am thinking mid range ones such as the Yamaha RX-A or V 2XXX, Denon AVR-3XXX and up. Also I said I had not seen many, but I have certainly seen some, just not too many, that advertise in ways that people could be misled.. And I always refer to the manufacturer's ads, not resellers.

You are so right about it is not the manufacturer who does this, not in this case but again I have seen some who does though.


The following is copied from yamaha.ca for the RX-V373:

Amplifier Section

Channel 5.1
Rated Output Power (1kHz, 1ch driven)
100W (8ohms, 0.9% THD)

Rated Output Power (1kHz, 2ch driven)
85W (8ohms, 0.9% THD)

Dynamic Power per Channel (8/6/4/2 ohms)
110/130/160/180W

Never said anything about ACD.

@PENG (I know no one can read my mind) that right there some funny Sh$t! after all these year's lolo. Still slamming them.