tag:blogger.com,1999:blog-4781727111866727703.post7554994140442837152..comments2024-03-29T00:15:52.117-07:00Comments on <em>Archimago's Musings</em>: The "Measurement Of Amplifiers Rig" (MOAR): Standard Tests, Loopback results, and the AMOAR Score.Archimagohttp://www.blogger.com/profile/08642574001287787545noreply@blogger.comBlogger39125tag:blogger.com,1999:blog-4781727111866727703.post-52583922688019369982022-04-08T13:45:50.016-07:002022-04-08T13:45:50.016-07:00You could actually convert centimeter to inches by...You could actually convert centimeter to inches by just using simple calculations. Conversions don't include any difficult steps of divisions or multiplications. You may either calculate it manually with pen and paper or use a calculator . <a href="https://becalculator.com/" rel="nofollow">cm to inches</a><br />Tom Jeehttps://www.blogger.com/profile/17919892459656318436noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-33756417110551575212019-12-05T13:38:23.074-08:002019-12-05T13:38:23.074-08:00I just realized that I didn't provide any way ...I just realized that I didn't provide any way to see my test results. :-( So here's a link to the Amazon review I posted of the "bad" DAC. <br /><br />https://www.amazon.com/gp/customer-reviews/R39SHBBDLH41U9/ref=cm_cr_dp_d_rvw_ttl?ie=UTF8&ASIN=B072BH3BYN<br /><br />The fact that it really doesn't sound awful (except for the notably rolled-off bass) makes me even moregregdunnhttps://www.blogger.com/profile/09171638815902122566noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-88220712128595126742019-11-25T13:32:16.310-08:002019-11-25T13:32:16.310-08:00Me too, I've dropped you an email a couple of ...Me too, I've dropped you an email a couple of days ago, please check your inbox.Mikhailhttps://www.blogger.com/profile/03247181793198240403noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-71221110494340115802019-11-23T14:13:01.081-08:002019-11-23T14:13:01.081-08:00I did a test with a Linkwitz signal: sine 1kHz, 5....I did a test with a Linkwitz signal: sine 1kHz, 5.1kHz amplitude 1:1.<br />200ms long in a period of 375ms (=160 BPM).<br />I then windowed with acourate (audiovero), Blackman Optimal window.<br /> <br /><br />I put periods togehter so as to have a 10sec signal.<br />I then feeded the amp and observed the distortion on ARTA (Relatime Spectrumanalyzer).<br />The waveform I observed and measured Dipolaudiohttps://www.blogger.com/profile/10741776789850117270noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-73397633499348220292019-11-22T08:41:52.849-08:002019-11-22T08:41:52.849-08:00BTW Mikhail,
Could you E-mail me at archimagosmusi...BTW <em>Mikhail</em>,<br />Could you E-mail me at <em>archimagosmusings@outlook.com</em>. Would love to chat about the QA product!Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-89560334515547697702019-11-21T21:10:20.454-08:002019-11-21T21:10:20.454-08:00Wow Greg, that's a bad DAC!
Indeed it's s...Wow <em>Greg</em>, that's a bad DAC!<br /><br />Indeed it's surprising sometimes just how accommodating the ears can be even with what one would think should be amazingly terrible results like the amount of distortion you saw.<br /><br />While ultimately it's about "good sound", if we're talking about verification of a device's fidelity, I think it's important Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-12229207221329452822019-11-21T21:00:02.539-08:002019-11-21T21:00:02.539-08:00Hi Dipolaudio,
Manually and very carefully :-).
A...Hi <em>Dipolaudio</em>,<br />Manually and very carefully :-).<br /><br />At the higher power I've just used the 1kHz sine captured in realtime on REW. Will only take a couple seconds to grab the THD+N result at each level so will not push the amp too long at the higher constant output.<br /><br />Also, since I'm aiming at a relatively conservative 0.1%, I'm not going to push the amp Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-24790628864809068762019-11-21T13:15:59.578-08:002019-11-21T13:15:59.578-08:00I know the software ARTA and accourate (audiovero)...I know the software ARTA and accourate (audiovero).<br />Both measure with logsweep signal, ARTA also with PN-Noise signal.<br />None of them with cycled multitone burst however.<br />REW I do not know.Dipolaudiohttps://www.blogger.com/profile/10741776789850117270noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-19269101081038381012019-11-21T13:12:24.749-08:002019-11-21T13:12:24.749-08:00Quote: How you measure this?
"Finally, the l...Quote: How you measure this?<br /><br />"Finally, the last number, the Power Factor, indicates the number of volts an amplifier can deliver at the top end before it hits 0.1% THD+N (-60dB) into 4Ω. This will give us an idea of how much power is available for the needs of the high fidelity enthusiast since 0.1% should still sound quite good even if a little "colored"."<br /><brDipolaudiohttps://www.blogger.com/profile/10741776789850117270noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-17942077152354984882019-11-20T23:54:17.416-08:002019-11-20T23:54:17.416-08:00Good point about defending insecurities! I think ...Good point about defending insecurities! I think we can make ourselves believe many reasonable-sounding things as long as they're not disproven by objective facts. And when your livelihood depends on supporting the belief that certain differences are clearly audible (though perhaps only to the discerning listener!) lots of questionable assertions become unchallenged memes.<br /><br />Just gregdunnhttps://www.blogger.com/profile/09171638815902122566noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-10381666404808943192019-11-20T21:29:18.821-08:002019-11-20T21:29:18.821-08:00Thanks for your comment Greg,
Certainly appreciate...Thanks for your comment <em>Greg</em>,<br />Certainly appreciate hearing from the "reasonable audiophiles" out there willing to put themselves (and friends) to the test whether it's the preamps in the 70's or the digital codecs :-).<br /><br />I agree with your comment "They actually measured rather differently, but the ear only cared about level and frequency response Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-82497986852281644772019-11-20T21:09:39.663-08:002019-11-20T21:09:39.663-08:00Excellent! Good to know.Excellent! Good to know.Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-41116591593581969602019-11-20T21:08:52.255-08:002019-11-20T21:08:52.255-08:00Yeah... Whether ratio or % those are horrible numb...Yeah... Whether ratio or % those are horrible numbers :-).<br /><br />Either way, I certainly want to listen to much more accurate high fidelity amplifiers! Lemme know if you find an answer <em>Mikhail</em>.Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-14911587567994248172019-11-20T21:04:26.613-08:002019-11-20T21:04:26.613-08:00Thanks John! Wow, brilliant stuff. You've real...Thanks John! Wow, brilliant stuff. You've really created one heck of a program as a "team of one".<br /><br />I checked the issue on my other machine and interestingly what I found was that this was not an issue there with a fresh install. So what I did was do a reinstall of beta 28 and the issue is no longer present on my Surface Pro.<br /><br />I suspect what happened must have Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-87677156269186978412019-11-20T20:32:31.032-08:002019-11-20T20:32:31.032-08:00Very cool test! And challenging!Very cool test! And challenging!Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-71027691417282009882019-11-20T20:26:22.701-08:002019-11-20T20:26:22.701-08:00Hey Prep,
Thanks, missed that video. Good on Ethan...Hey <em>Prep</em>,<br />Thanks, missed that video. Good on Ethan Winer for calling out Paul McGowan :-). LOL, Paul claims unable to measure timbre of instruments... Bizarre. I mean seriously, who even believes that!?<br /><br />Yeah, of course McGowan will not accept the challenge of a debate. He's a good salesman and makes some good products (and hype up very questionable ones also like the Archimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-42549692136319751762019-11-20T20:09:52.419-08:002019-11-20T20:09:52.419-08:00Thanks Miska,
Yeah, I was thinking of pushing this...Thanks <em>Miska</em>,<br />Yeah, I was thinking of pushing this to 192kHz. Looking at the L&O&C paper:<br />http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=98A75F6B92DB797FDBE18584E6627651?doi=10.1.1.394.9799&rep=rep1&type=pdf<br /><br />Looks like there are quite a number of options for the square and sine wave frequencies. So long as the square harmonics do not overlapArchimagohttps://www.blogger.com/profile/08642574001287787545noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-73603591250571851432019-11-20T12:37:07.919-08:002019-11-20T12:37:07.919-08:00I have been using REW for my measurements as well,...I have been using REW for my measurements as well, and it's excellent for speaker measurement as well as for amps and preamps. My needs are modest, but I've found the Scarlett 2i2 is quite decent for an inexpensive test rig. When all audio enthusiasts have something so simple and easy to use for testing gear, perhaps we will get more measurements and less speculation. I can hope.<br />gregdunnhttps://www.blogger.com/profile/09171638815902122566noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-16136920927039346622019-11-20T09:16:02.666-08:002019-11-20T09:16:02.666-08:00Regarding "One REW bug I need to mention is t...Regarding "One REW bug I need to mention is that the triple-tone signal generator often will not activate the custom frequency settings until I manually change the frequencies individually. I'll try to leave a note on this in the REW beta feedback. I am looking forward to what else the developers have up their sleeves."<br /><br />I'm a development team of one, but I'll be JohnMhttps://www.blogger.com/profile/05012457874837383527noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-31459698607437132432019-11-20T09:05:46.059-08:002019-11-20T09:05:46.059-08:00the claim of Paul McGowan is a common myth for eve...the claim of Paul McGowan is a common myth for every audio device.<br />Its just nonsense. <br />Actually it is much more measurable than can be heard.<br />Tru is that the relation of mesurmenet to how its perceived is not so clear and statistical. Some perceice it different then others.<br /><br />Have you done the experiment of base-tone versus overtone audio perception. Interresting. Its Dipolaudiohttps://www.blogger.com/profile/10741776789850117270noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-74747783395964287342019-11-19T20:55:16.084-08:002019-11-19T20:55:16.084-08:00Hi Arch
Great to see these amp tests. While on th...Hi Arch<br /><br />Great to see these amp tests. While on this subject, you might be interested in this you tube video by Ethan Winer where he challenges Paul McGowan from PS Audio to a debate. Paul claims (in another you tube video) that we cannot measure everything that can be heard coming out of amplifiers and that null tests are invalid. That was back in January and Paul still hasn't Prep 74https://www.blogger.com/profile/01821201947031867789noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-83369766161058544862019-11-19T14:38:15.575-08:002019-11-19T14:38:15.575-08:00For TIM measurements, I'm using the values fro...For TIM measurements, I'm using the values from the Leinonen & Otala & Curl original measurement specification paper. 3.18 kHz square and 15 kHz sine, 1:5.66 amplitude ratio, filtered by first order low pass with fc=100 kHz.<br /><br />My test signal is sampled at 768 kHz.<br /><br />500 Hz + 6 kHz sounds like way too relaxed, and the 48 kHz bandwidth doesn't really push the gear.Miskahttps://www.blogger.com/profile/11943166800124292464noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-73264309761415736152019-11-19T11:32:03.503-08:002019-11-19T11:32:03.503-08:00I agree that unless one wants to match the manufac...I agree that unless one wants to match the manufacturer specified figures precisely, and one uses AP for doing measurements, use of "physical" low pass filter is not required for Class D amps. Here is a blog post from QuantAsylum where they compare specs from the manufaturer vs what they have measured using QA401 w/o any filter: https://quantasylum.com/blogs/news/Mikhailhttps://www.blogger.com/profile/03247181793198240403noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-76590277045986634952019-11-19T11:21:22.415-08:002019-11-19T11:21:22.415-08:00Good question, Archimago! Unfortunately, I can'...Good question, Archimago! Unfortunately, I can't ask Dr. Lee himself. The help page for Spectra Plus says that THD is measured in %: https://www.spectraplus.com/SC_help/total_harmonic_distortion.htm, the page about IMD says it's a "ratio". On the graphs, we can see THD going up to 50%, while IMD goes up to 140. I suppose, some of their samples were indeed heavily distorted for Mikhailhttps://www.blogger.com/profile/03247181793198240403noreply@blogger.comtag:blogger.com,1999:blog-4781727111866727703.post-17143091136485058432019-11-19T10:39:03.215-08:002019-11-19T10:39:03.215-08:00Hi Archimago,
Thank you for positive feedback. ...Hi Archimago, <br /><br />Thank you for positive feedback. <br /><br />On the load resistors adding distortion I had lower power ones that weren't wire wound and used that as my reference for figuring out the big 200W ones were causing distortion. I also experimented with adding inductance as theoretically a non-resistive load (i.e. a real speaker) is going to modify the amps performance Brewsterhttps://www.blogger.com/profile/03746254769353743631noreply@blogger.com