Lonnie
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Post by Lonnie on Feb 26, 2020 12:07:26 GMT -5
RMC-1 on audiosciencereview.comRay Dennison - Sr. Design Engineer, Emotiva Audio Corp. Apples and Oranges Before I comment on the test results of the RMC-1 recently reviewed in your lab, Iād like to mount a defense of not just Emotiva, but of all the processors reviewed and compared unfavorably to 2-channel DACs. They are simply not the same thing. Weāve got to compare apples to apples, so to speak.
The analog path in a typical 2-channel DAC consists of a DAC chip and some sort of analog filter and buffer. With this structure you can get very close to the raw DAC chip specifications with just minor degradation due to the power supply, op-amps, resistors, etc. Performance under your test conditions looks great. However, if you were to retest with more typical listening levels you would find that SNR, THD, etc. may be degraded. One can design a home theater processor the same way and get the same excellent results under your test conditions. However, a processor needs to account for listening levels, surround processing, downmixing, bass management, EQs, varying amplifier gains and widely varying speaker efficiencies. If our hypothetical processor does not account for these signal processing needs, then it will perform just as well as the 2-channel DACs. However, if I add EQ, require some downmixing or speaker balancing, etc. then our hypothetical processor clips and sounds bad. Some inexpensive processors try to get around this by adding headroom in the DSP. You figure out the worst-case gain that might need to be applied due to signal processing requirements, attenuate all the signals by that amount and bring the level back in the analog output buffers. Unfortunately, the headroom ends up being in the neighborhood of 30 - 40dB. So now my 24-bit 120dB DAC is now a 17-bit, 80dB DAC. Not ideal. The high-end way to do this is by using an analog volume control after the DAC. This allows you to adjust the headroom only as needed for the current processing requirements. Iām confident that all of those ābadā processors reviewed use some sort of analog volume control. But we must be aware; analog volume controls are not perfect. At one end you have the noise floor; if your incoming signal is relatively low, then the overall SNR is dominated by the volume controls noise. If you use a higher-level input signal, then the volume control will distort; not good! The designer must choose a sweet spot between SNR and distortion. This analog volume control in the signal path is the main reason you canāt compare 2-channel DACs to HT processors. There are many other, more subtle issues, but this is the main one. Emotiva designs tend to be biased somewhat towards highest practical SNR, over lowest distortion. Our distortion levels at 0dBFS may be a bit higher than some other brands, but our SNR may be lower. This is a design choice based on real-world conditions. Signals are seldom at 0dBFS and when they are the speaker distortion will be orders of magnitude higher. But this is just my opinion, man. Your mileage may vary. Another designer may feel that optimizing for distortion is the better choice. In either case, the distortion will be better at more reasonable levels. Most reviewers (and spec. writers for manufacturers) use a more reasonable -20dBFS for distortion measurements.
The main point of this discussion is that comparing a home theater processor against a DAC or dongle is simply not valid. Conflating the distortion measurement with SNR measurement simply adds to the confusion. IMO, the SINAD measurement just adds more confusion. SINAD is exactly the same as THD + Noise. People are used to seeing THD + Noise measurements. No one will complain about .005% at 0dBFs, full volume. But converting this to dB makes it look bad to the uninformed. None of the processors you have reviewed are bad compared to 2-channel DACs. They simply have different functions, technical requirements, and circuit topologyās. Respectfully, I suggest that they should be tested differently. RMC-1 measurementsOn to the specifics of the RMC-1 review. I do not know the exact test conditions used with the Audio Precision or the RMC-1. I am using PCM 48/24 from my lab AP 585 over HDMI. I am using a factory reset RMC-1, and have all speakers set to large and am in āDirectā mode. It is using the recently released v1.8 code. Here is our test result using the view similar to first part of the review. I do not see anything other than expected small 2nd, 3rd, and 5th harmonic distortion. I canāt comment on the spurious signals the reviewer saw because I donāt see them. Perhaps there is some setup difference on the AP or RMC-1 that might account for this. Note that the THD+N (and SINAD) measurements are essentially identical to the review even without the spurious signal. So how useful is this measurement?
Yes, the THD+N is higher than a 2-channel DAC. Please see discussion above regarding analog volume controls and our design choice to optimize for better SNR. Here is the same test with -20dbFS signal. This is an extremely clean and quiet signal. Not too shabby. I donāt have time right now to re-run all the tests in the review, but here are a few highlights. Jitter test (48kHz). Unclear why our result is so different from the reviewerās.
Note, no weirdness. Nice and clean. THD vs frequency. Testing at 0dBFs I get similar results as in the review. The .1% @ 20Hz seems high, but your sub will likely be at 10% THD!! Again, design choices, based on experience and reality. The benefits in overall performance using analog attenuators overwhelmingly outweigh the slight THD penalty at low frequencies and high signal levels. THD (not THD+N) vs frequency at -20dBFS: Rising THD at low frequency is characteristic of the analog volume control. Not bad power supply design.
I measure slightly better SNR (>119dB) than the reviewer (116dB) but that is a small difference and excellent either way, Itās also unclear why the reviewer observed differences between Direct and Reference Stereo modes. With 2 PCM stereo coming in and large front speakers, there should be no difference at all. The power of āReference Stereoā really comes in play for analog signals. Reference Stereo is a true analog bypass of the analog signal to the volume controls via relay. This raises the performance to that of a high-end analog pre-amp. Note the flat response to the limits of the Audio Precision and very low distortion, even at the 4V levels used by the reviewer. SNR was >123dB under these conditions. So, as you can see, things are sometimes more complex that they first appear. The RMC-1 and its offspring are well designed AV processors with excellent measured performance and outstanding sound quality. This is what I have been saying about comparing a DAC to a AV processor glad you have the same conclusion. I did just did the update on my XMC-2 to 1.8 last night (posted this in the XMC-2 thread also). Had some issues with the usb input not working with my Ropiee box (when playing 192khz24bit tracks it would cut out and skip). I was able to turn UAC2 off and back on and reset my xmc-2 a few times and got it to work. I will have to see tonight if it still works. My question is after doing the firmware update do you recommend resetting to factory settings and redoing the settings? I noticed you did this for your review and want to know if it is recommended. This is what I do so I have a clean point of reference with each code update. You don't have to, its just what I do. Back up settings. Load in new code. When finished, I do a factory default reset. Turn everything off and unplug for a few seconds. The reason I do this is because most gear holds EDID and info frame data in memory and this just forces a clean read of all the gear. Turn everything on and let it all boot up. Load in settings and you are good to go. Lonnie
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Post by thxultra on Feb 26, 2020 12:10:25 GMT -5
This is what I have been saying about comparing a DAC to a AV processor glad you have the same conclusion. I did just did the update on my XMC-2 to 1.8 last night (posted this in the XMC-2 thread also). Had some issues with the usb input not working with my Ropiee box (when playing 192khz24bit tracks it would cut out and skip). I was able to turn UAC2 off and back on and reset my xmc-2 a few times and got it to work. I will have to see tonight if it still works. My question is after doing the firmware update do you recommend resetting to factory settings and redoing the settings? I noticed you did this for your review and want to know if it is recommended. This is what I do so I have a clean point of reference with each code update. You don't have to, its just what I do. Back up settings. Load in new code. When finished, I do a factory default reset. Turn everything off and unplug for a few seconds. The reason I do this is because most gear holds EDID and info frame data in memory and this just forces a clean read of all the gear. Turn everything on and let it all boot up. Load in settings and you are good to go. Lonnie Thanks for the info it is much appreciated.
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Lsc
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Post by Lsc on Feb 26, 2020 12:33:39 GMT -5
How many people who are in here have no idea how to actually interpret these results and/or have the background to speak about this topic intelligently and have a frame of reference? I donāt qualify- so all I can say is things like my stuff sounds good. Actually pretty damn good. Thatās good enough for me - wake me up when itās over š.
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Post by dj7675 on Feb 26, 2020 12:58:06 GMT -5
RMC-1 on audiosciencereview.comRay Dennison - Sr. Design Engineer, Emotiva Audio Corp.
Apples and Oranges Before I comment on the test results of the RMC-1 recently reviewed in your lab, Iād like to mount a defense of not just Emotiva, but of all the processors reviewed and compared unfavorably to 2-channel DACs. They are simply not the same thing. Weāve got to compare apples to apples, so to speak.
The analog path in a typical 2-channel DAC consists of a DAC chip and some sort of analog filter and buffer. With this structure you can get very close to the raw DAC chip specifications with just minor degradation due to the power supply, op-amps, resistors, etc. Performance under your test conditions looks great. However, if you were to retest with more typical listening levels you would find that SNR, THD, etc. may be degraded.
One can design a home theater processor the same way and get the same excellent results under your test conditions. However, a processor needs to account for listening levels, surround processing, downmixing, bass management, EQs, varying amplifier gains and widely varying speaker efficiencies. If our hypothetical processor does not account for these signal processing needs, then it will perform just as well as the 2-channel DACs. However, if I add EQ, require some downmixing or speaker balancing, etc. then our hypothetical processor clips and sounds bad.
Some inexpensive processors try to get around this by adding headroom in the DSP. You figure out the worst-case gain that might need to be applied due to signal processing requirements, attenuate all the signals by that amount and bring the level back in the analog output buffers. Unfortunately, the headroom ends up being in the neighborhood of 30 - 40dB. So now my 24-bit 120dB DAC is now a 17-bit, 80dB DAC. Not ideal.
The high-end way to do this is by using an analog volume control after the DAC. This allows you to adjust the headroom only as needed for the current processing requirements. Iām confident that all of those ābadā processors reviewed use some sort of analog volume control. But we must be aware; analog volume controls are not perfect. At one end you have the noise floor; if your incoming signal is relatively low, then the overall SNR is dominated by the volume controls noise. If you use a higher-level input signal, then the volume control will distort; not good! The designer must choose a sweet spot between SNR and distortion. This analog volume control in the signal path is the main reason you canāt compare 2-channel DACs to HT processors. There are many other, more subtle issues, but this is the main one.
Emotiva designs tend to be biased somewhat towards highest practical SNR, over lowest distortion. Our distortion levels at 0dBFS may be a bit higher than some other brands, but our SNR may be lower. This is a design choice based on real-world conditions. Signals are seldom at 0dBFS and when they are the speaker distortion will be orders of magnitude higher. But this is just my opinion, man. Your mileage may vary. Another designer may feel that optimizing for distortion is the better choice. In either case, the distortion will be better at more reasonable levels. Most reviewers (and spec. writers for manufacturers) use a more reasonable -20dBFS for distortion measurements.
The main point of this discussion is that comparing a home theater processor against a DAC or dongle is simply not valid. Conflating the distortion measurement with SNR measurement simply adds to the confusion. IMO, the SINAD measurement just adds more confusion. SINAD is exactly the same as THD + Noise. People are used to seeing THD + Noise measurements. No one will complain about .005% at 0dBFs, full volume. But converting this to dB makes it look bad to the uninformed. None of the processors you have reviewed are bad compared to 2-channel DACs. They simply have different functions, technical requirements, and circuit topologyās. Respectfully, I suggest that they should be tested differently.
RMC-1 measurementsOn to the specifics of the RMC-1 review. I do not know the exact test conditions used with the Audio Precision or the RMC-1. I am using PCM 48/24 from my lab AP 585 over HDMI. I am using a factory reset RMC-1, and have all speakers set to large and am in āDirectā mode. It is using the recently released v1.8 code. Here is our test result using the view similar to first part of the review.
I do not see anything other than expected small 2nd, 3rd, and 5th harmonic distortion. I canāt comment on the spurious signals the reviewer saw because I donāt see them. Perhaps there is some setup difference on the AP or RMC-1 that might account for this. Note that the THD+N (and SINAD) measurements are essentially identical to the review even without the spurious signal. So how useful is this measurement?
Yes, the THD+N is higher than a 2-channel DAC. Please see discussion above regarding analog volume controls and our design choice to optimize for better SNR.
Here is the same test with -20dbFS signal. This is an extremely clean and quiet signal.
Not too shabby.
I donāt have time right now to re-run all the tests in the review, but here are a few highlights. Jitter test (48kHz). Unclear why our result is so different from the reviewerās.
Note, no weirdness. Nice and clean.
THD vs frequency. Testing at 0dBFs I get similar results as in the review. The .1% @ 20Hz seems high, but your sub will likely be at 10% THD!! Again, design choices, based on experience and reality. The benefits in overall performance using analog attenuators overwhelmingly outweigh the slight THD penalty at low frequencies and high signal levels.
THD (not THD+N) vs frequency at -20dBFS:
Rising THD at low frequency is characteristic of the analog volume control. Not bad power supply design.
I measure slightly better SNR (>119dB) than the reviewer (116dB) but that is a small difference and excellent either way,
Itās also unclear why the reviewer observed differences between Direct and Reference Stereo modes.
With 2 PCM stereo coming in and large front speakers, there should be no difference at all. The power of āReference Stereoā really comes in play for analog signals. Reference Stereo is a true analog bypass of the analog signal to the volume controls via relay. This raises the performance to that of a high-end analog pre-amp. Note the flat response to the limits of the Audio Precision and very low distortion, even at the 4V levels used by the reviewer. SNR was >123dB under these conditions.
So, as you can see, things are sometimes more complex that they first appear. The RMC-1 and its offspring are well designed AV processors with excellent measured performance and outstanding sound quality. Thank you for providing some measurements. Why .5volts when that is not the amount reqjuired to drive Emotiva Amps? Isn't that value 1.5 or 2volts? Can the tests be run with a more realistic value?
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Post by Mikomill on Feb 26, 2020 12:59:42 GMT -5
How many people who are in here have no idea how to actually interpret these results and/or have the background to speak about this topic intelligently and have a frame of reference? I donāt qualify- so all I can say is things like my stuff sounds good. Actually pretty damn good. Thatās good enough for me - wake me up when itās over š. ....And how many have no idea how to interpret these results but think they do? There seems to be no shortage of members that can tell Emo exactly why the problems exist and how it fix them. "The power supply is to small" , "we should have firmware updates every month" and on and on and on. Product suggestions are one thing but complaining about the same thing over and over again is getting old real fast.
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Post by urwi on Feb 26, 2020 13:03:21 GMT -5
You keep saying Amir would test differently than you and the rest of the industry. In fact he is using the same gear you use running the same tests. They are standardized. There's nothing subjective about it. What exactly he tested is all documented at www.audiosciencereview.com/forum/index.php?threads/emotiva-rmc-1-av-processor-review.11673/His data suggests there are problems with the DUT. The question is why a RMC with the latest firmware out in the wild shows such misbehavior? Please consider it is NOT incompetence of the person doing the test. Just as a point of reference. Our production AP test are run on every processor when they are first built and again after burn in. The same production AP test is run on any processor that comes back to the company for any reason. Unit to unit and over time, the results are always constant. Why ASR measures differently is not a function of time or variances in production but in test procedures. As I have stated before, we use standardized test that virtually every other audio company in the world uses, so to get to the bottom of why they are different would be asking Amir how he test. One last thing, the setting on the volume control is not the level that is being referenced in the test. That level is a function of input signal level, not output. Best regards, Lonnie
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hi
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Post by hi on Feb 26, 2020 13:05:42 GMT -5
I saw the Results Hair Nick posted. Thought i made someting wrong with my measurements; Redid them: 1. Upgrading FW: 1.8 again 2. Unplug everything 3. FW Reset 4. Power disconnect 5mins 5. Front speaker @ Large all other to NONE 6. Measured over HDMI & USB @ 48khz 96khz 192khz 7. Mode Direct & Reference Stereo 8. Measured with ARTA Spectrum Analyzer 9. Result: - Where is the error? - Did i someting wrong? - Is My RMC-1 Defective? - Why are my results similar to the measurements from ASR and not to the official ones? P.S.: Loopback test of my Interface:
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Post by SOWK on Feb 26, 2020 13:17:03 GMT -5
I saw the Results Hair Nick posted. Thought i made something wrong with my measurements; Redid them: 1. Upgrading FW: 1.8 again 2. Unplug everything 3. FW Reset 4. Power disconnect 5mins 5. Front speaker @ Large all other to NONE 6. Measured over HDMI & USB @ 48khz 96khz 192khz 7. Mode Direct & Reference Stereo 8. Measured with ARTA Spectrum Analyzer 9. Result: - Where is the error? - Did i someting wrong? - Is My RMC-1 Defective? - Why are my results similar to the measurements from ASR and not to the official ones? They tested with a -20dbFS signal.
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koeitje
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Post by koeitje on Feb 26, 2020 13:19:00 GMT -5
Can you enlighten me on what the problems are you run into when designing a multi channel device. Does DSP ruin everything in such a product? To my understanding a multi channel receiver does the following:
Digital input -> DSP processing -> DAC -> Output stage (volume control, if not integrated in the DAC).
It clearly isn't the amount of channels, because you can have very high performance in multi channel DACs for a very reasonable price (https://www.oktoresearch.com/dac8pro.htm, I believe they even use a single DAC and don't sum channels). Nor is it the volume control/pre-amp section, because those also easily go to <0.0006% THD+N in modern gear.
So that leaves us with the amount of noise in the chassis from all the electronics in there or the power supply section and the DSP. Do you use 32bit floating DSP? Am I missing something?
Can you also explain why you say you want industry standard measurements, but don't measure the output at 2v and 4v industry standards? Seems a bit counter intuitive to me.
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Lonnie
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Post by Lonnie on Feb 26, 2020 13:23:16 GMT -5
You keep saying Amir would test differently than you and the rest of the industry. In fact he is using the same gear you use running the same tests. They are standardized. There's nothing subjective about it. What exactly he tested is all documented at www.audiosciencereview.com/forum/index.php?threads/emotiva-rmc-1-av-processor-review.11673/His data suggests there are problems with the DUT. The question is why a RMC with the latest firmware out in the wild shows such misbehavior? Please consider it is NOT incompetence of the person doing the test. Just as a point of reference. Our production AP test are run on every processor when they are first built and again after burn in. The same production AP test is run on any processor that comes back to the company for any reason. Unit to unit and over time, the results are always constant. Why ASR measures differently is not a function of time or variances in production but in test procedures. As I have stated before, we use standardized test that virtually every other audio company in the world uses, so to get to the bottom of why they are different would be asking Amir how he test. One last thing, the setting on the volume control is not the level that is being referenced in the test. That level is a function of input signal level, not output. Best regards, Lonnie Yes, the AP are standardized, but the test he is running is not a canned test. If you have ever used an AP, you know you have the ability to set up a test in anyway you want or you can choose to use a canned test. No incompetence stated or implied. Just like a previous post I did, he simply chooses to do his test in his way. I'm not saying he is wrong, its just different. I'm not picking a fight here, I'm simply presenting the facts. Lonnie
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Post by rbk123 on Feb 26, 2020 13:24:31 GMT -5
You keep saying Amir would test differently than you and the rest of the industry. In fact he is using the same gear you use running the same tests. They are standardized. There's nothing subjective about it. There's a difference between having the same test equipment and running the same tests with said equipment. You seem to think if you have the same gear you can only run the same tests. (Sigh. Looks like Lonnie can type faster than me.) What a never ending rabbit hole of pseudo-science and armchair engineering the measurement discussions always turn into. "Can you also run this test?" "What about the results on this test, but not on this test?" "Can you try this..."
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Post by adaboy on Feb 26, 2020 13:27:28 GMT -5
amirm amirm Founder/Admin Staff Member CFO (Chief Fun Officer) 25 minutes agoNew #305 I have to run soon but thought to address this in their measurement notes: 1582739743559.png First, they should have run this test at 0 dB as I did if they want to say I don't test things correctly. Instead, they ran it at -20 dBFS. That aside, they should show whose analog volume control IC they are using that acts this way. Here is a quick sample from TI: www.ti.com/lit/ds/symlink/pga2311.pdf1582739800480.png There is no rising distortion at low frequencies. It is the opposite as one would expect with typical analog buffers. That final drop by the way is an instrumentation issue with limited bandwidth of the test TI ran. With higher bandwidth it would just keep climbing proportional with frequency. Not the other way around as the RMC-1 is doing. Here is the Monoprice HTP-1 which is their competitor: This pattern closely matches the TI albeit, still has a small rise in low frequencies. This is RMC-1 in the same measurement again: They seem to want to constantly shift blame instead of looking at what is wrong with their product and fixing it.
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Post by adaboy on Feb 26, 2020 13:28:34 GMT -5
amirm amirm Founder/Admin Staff Member CFO (Chief Fun Officer) 11 minutes agoNew #308 carlob said: measurements are in: emotivalounge.proboards.com/post/1022230/threadThanks. Addressing this bit: There is no such thing as "jitter test" in APx555. The way "jitter test" is performed is by using a special test signal called J-test that is a square wave inside another squarewave. The first square wave gets filtered by the DAC and becomes a sine wave at 12 kHz (48 kHz sampling). The second one is almost invisible and runs at 250 Hz. It simply toggles the low order bit of the signal which causes all the bits to change. In decimal numbers it would be like going from 1.00000 to 0.99999. If there is data dependency in the DAC, i.e. the digital bit stream bleeds into the analog output of the DAC, the toggling of all the bits tease it out. There is no indication that the above is the test they ran. For some reason AP makes it hard to find the J-test signal as I have had to provide to many people who run this test. I suspect they are just running a 12 kHz sine wave and calling it the day. There are also presentation issues in their measurement: To see the 250 Hz component, you need to make sure there is ample room around our tall 12 kHz tone to see them. There are actually sidebands visible on both sides of the tall line but they are so close they are hard to see. Compare that to way I show the same data: Another critical difference in their test versus mine is averaging and high resolution FFT. I use 16 times averaging which shrinks the bottom of the skirt and high resolution of 256 K FFT. These are critical to do to see small jitter contributions. Without careful setup of the test, it is easy to not see issues. All of this is a shame as I reached out to them and could have easily provided them my project files so that they run them as I do. Or complain if they think something is wrong with them.
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hi
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Post by hi on Feb 26, 2020 13:35:32 GMT -5
I also tested the RMC-1 @ -20db For lower error the preamp of the interface is at -6db. The thing is, i get 250hz and 500hz peaks which change constantly with the input sine signals. These peaks i cant see in the measurement from emotiva. But on the measurement from amir are they also present. I saw the ResultsĀ Hair Nick posted. Thought i made something wrong with my measurements; Redid them: 1. Upgrading FW: 1.8 again 2. Unplug everything 3. FW Reset 4. Power disconnect 5mins 5. Front speaker @ Large all other to NONE 6. Measured over HDMI & USB @ 48khz 96khz 192khz 7. Mode Direct & Reference Stereo 8. Measured with ARTA Spectrum Analyzer 9. Result: - Where is the error? - Did i someting wrong? - Is My RMC-1 Defective? - Why are my results similar to the measurements from ASR and not to the official ones? They tested with a -20dbFS signal.
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cawgijoe
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Post by cawgijoe on Feb 26, 2020 13:36:40 GMT -5
It's quite obvious that Amirm believes he is right and that Emotiva is running their tests incorrectly and that the RMC-1 platform is broken and needs to be fixed.
That's my summary from his posts.
I don't have any plans to fire-sale my XMC-2. It sounds great and I can't wait for Dirac.
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Lonnie
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Post by Lonnie on Feb 26, 2020 13:38:08 GMT -5
Can you enlighten me on what the problems are you run into when designing a multi channel device. Does DSP ruin everything in such a product? To my understanding a multi channel receiver does the following: Digital input -> DSP processing -> DAC -> Output stage (volume control, if not integrated in the DAC). It clearly isn't the amount of channels, because you can have very high performance in multi channel DACs for a very reasonable price (https://www.oktoresearch.com/dac8pro.htm, I believe they even use a single DAC and don't sum channels). Nor is it the volume control/pre-amp section, because those also easily go to <0.0006% THD+N in modern gear. So that leaves us with the amount of noise in the chassis from all the electronics in there or the power supply section and the DSP. Do you use 32bit floating DSP? Am I missing something? The DSP chip itself is not the issue. It all comes down to how you have to manage dynamic range, levels and the big one, bass management. Think of it like this. Both Dolby and DTS require a 10db boost of the LFE relative to the other channels. Since a DSP can't go above 0db, that means we have to lower all the other channels 10db to start. Now lets look at the bass management. We have to allow for the summation of all the low frequencies when the speakers are set too small. So that means we have to sum 15 channels of bass together and then add that to the already boosted LFE channel which means a lot of reduction in the HP channels to make sure the LP doesn't clip. Now add in EQs and Levels. For any boost that is done, more reduction is required to prevent the DSP from clipping. There are several other things that have to be accounted for as well, but those are the big ones. So is it starting to make since why a comparison of an ordinary DAC and a HT processor is like comparing Apples to Oranges? Lonnie
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Post by bluescale on Feb 26, 2020 13:41:37 GMT -5
Any insight into why the XMC-1 test so much better than the RMC-1?
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koeitje
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Post by koeitje on Feb 26, 2020 13:49:00 GMT -5
Can you enlighten me on what the problems are you run into when designing a multi channel device. Does DSP ruin everything in such a product? To my understanding a multi channel receiver does the following: Digital input -> DSP processing -> DAC -> Output stage (volume control, if not integrated in the DAC). It clearly isn't the amount of channels, because you can have very high performance in multi channel DACs for a very reasonable price (https://www.oktoresearch.com/dac8pro.htm, I believe they even use a single DAC and don't sum channels). Nor is it the volume control/pre-amp section, because those also easily go to <0.0006% THD+N in modern gear. So that leaves us with the amount of noise in the chassis from all the electronics in there or the power supply section and the DSP. Do you use 32bit floating DSP? Am I missing something? The DSP chip itself is not the issue. It all comes down to how you have to manage dynamic range, levels and the big one, bass management. Think of it like this. Both Dolby and DTS require a 10db boost of the LFE relative to the other channels. Since a DSP can't go above 0db, that means we have to lower all the other channels 10db to start. Now lets look at the bass management. We have to allow for the summation of all the low frequencies when the speakers are set too small. So that means we have to sum 15 channels of bass together and then add that to the already boosted LFE channel which means a lot of reduction in the HP channels to make sure the LP doesn't clip. Now add in EQs and Levels. For any boost that is done, more reduction is required to prevent the DSP from clipping. There are several other things that have to be accounted for as well, but those are the big ones. So is it starting to make since why a comparison of an ordinary DAC and a HT processor is like comparing Apples to Oranges? Lonnie 32bit floating dsp processing has like 1500+dB worth of dynamic range to play with, so you have more than enough dynamic range to do all the processing. I am comparing it because in essence a HT processor is the same as a chain of separate components. Components we know can perform at very high levels.
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Post by Mikomill on Feb 26, 2020 13:51:20 GMT -5
This is so weird! My RMC-1l sounded great last week Amirm came out with his review and then my RMC-1L sounded like crap. Emotiva posted their results this morning and My RMC-1L sounded great again. A few minutes ago Amirm posted his rebuttal and now my RMC-1L sounds like crap again!!!
What do you guys think the problem is? Is it the weight of the power supply or maybe its that blue light on the front of the unit. Maybe i should call Emotiva and report this..if they care at all about their customers they'll have a firmware update by the end of the day.
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Post by Gerard on Feb 26, 2020 13:51:32 GMT -5
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